Note: Descriptions are shown in the official language in which they were submitted.
63~5
SELF-EXTINGUISHING CIRC~IT BR~AKER COMPRISING
GAS PRE-COMPRESSION MEANS
BA~KGROUND OF THE INVENTION
This invention relates to a gas-blast switch for
interrupting an electric arc struck across a pair of station-
ary and movable contact members by blowing an arc extinguish-
ing fluid such as sulfurhexafluorlde (SF6) against the electric
arc, and more particularly to a self-arc-extinguishing type
switch utili~ing an arc-extinguishing fluid raised in pressure
with an electric arc struck across a pair of stationary and
movable contact members for extinguishing the electric arc.
Among puffer type switches for extinguishing the
electric arc struck across the stationary and movable contact
members by blowing the arc-extinguishing fluid such as sulfur
hexafluoride against the electric arc, here have been known
switches of the type including a pair of engageable contact
members arranged to be separated from each other within an
arc-extinguishing chamber of a predetermined volume to strike
an electric arc thereacross and an amount of an arc-extinguish-
ing fluid disposed in the arc-extinguishing chamber to be
expanded with thermal energy of the electric arc thereby to
increase in pressure after which the arc-extinguishing fluid
from the arc-extinguishing chamber is delivered to the exterior
thereof upon a spacing between both contact mernber reaching
a predetermined magnitude whereupon the resulting stream of
the arc-extinguishing fluid is operated to interrupt the
electric arc.
Switches of the type referred to are called self-
1~26315
extinguishing type switches because ti~e arc-extinguishincJ
operation is performed by utilizing the arc-ex-tinguishiny fluid
having a pressure increased with its own arc energy. Those
switches have eliminated the necessity of providing additionally
means for pressurizing the arc-extinguishing fluid which have
been required for conventional puffer type switches so that
the resulting structure is simple and economical.
On the other hand, switches of the type referred to
might not satisfactorily pressurize the arc-extinguishing fluid
upon interrupting low currents because the resulting arc energy
is low. In order to avoid this objection, Japanese laid-open
patent publication No. 25,869/78, (corresponding to Japanese
patent application No. 1,013,070/1976 filed on August 24, 1976
in the name of Mitsubishi Denki Kabushiki Kaisha and naming
Koji Ibuki and Yoshihiro Ueda as inventors), for example, dis-
closes a pressurizing piston disposed in an arc-extinguishing
chamber to interlock with the operation of separating a pair
of contact member from each other thereby to pressurize the
arc-extinguishing fluid auxiliary. The piston is arranged to
be moved over the entire volume of the arc-extinguishing
chamber to compress the arc-extinguishing fluid. Therefore,
upon interrupting a high current having high arc energy, the
arc-extinguishing fluid has much increased in pressure while
its temperature rises excessively resulting in the deteriora-
tion of the interrupting performance. Also the arc-extinguish-
ing chamber becomes extremely small in volume because of the
movement of the piston as described above and therefore very
high in fluid pressure. This has resulted in the necessity
of using high-power operating means for operating the piston
as well as the necessity of providing closing means having a
high-power sufficient to overcome a force generated by the
operating means.
-- 2
,;,
315
. ~,
I
If the fluid pressure within the arc--extinyuishing
chamber overcomes the force for operating the piston then
the piston is moved toward its initial inoperative position.
This has resulted in a reduction in fluid pressure within
the arc-extinguishing chamber and therefore in interrupting
performance. With the piston made integrally with the
stationary contact member, the movable contact member might
repeat alternating engagement with and disengagement from
the stationary contact member resulting in the occurrence of .
the chattering. Under these circumstances, if electric arcs
strike across both contact members then there has been a fear
that both contact members are fused to each other. h
Accordingly, it is an object of the present
invention to provide a new and improved self-extinguishing
switch having 'che excellent interrupting performance by
increasing a pressure of an arc-extinguishing fluid to be
fit for interrupting currents within a wide range of from a ~r
low to a high magnitude thereby to exert the puffer action
on an electric arc struck across a pair of stationary and
movable contact members. ~ ~,
It is another object of the present invention to
provide a new and improved self-extinguishing switch capable
of interrupting efficiently a current even though would be
low.
It is still another object of the present invention
to provide a new and improved self-extinguishing type switch
having a long time interval for which an arc-extinguishing
fluid blown against an electric arc involved.
- 3 -
.
liZ631~
It is a different object of the present invontion ¦
to provide a self~extinguishing switch improved in in-terrupting
characteristics concerning high currents while retaining the T~,
good interrupting performance concerning low currents. ,
It is another object of the present invention to -
provide a new and improved self~extinguishing type switch
capable of reserving a proper amount of an arc-extinguishing
fluid raised inpressure up to the interruption of an electric
are involved.
It is another object of the present invention to
provide a new and improved self-extinguishing type switch
ineluding means for controlling a temperature rise of an
are-extinguishing fluid and maintaining a pressure thereof
as high as possible.
It is another object of the present invention to
provLde a new and improved self-extinguishing type switch ;
preventing a pair of stationary and movable contact members
from being fused to eaeh during the closing operation without
the deterioration in interrupting performance.
It is a separate objeet of the present invention
to provide a new and improved self-extinguishing type switch
including simplified operating means and having the
stabilized interrupting performance.
.
'1
SUMMARY OF THE INVENTION ~'
The present invention provides a self-extinguishing
type switeh comprising, a hollow cylindrical member, an ii
amount of arc-extinguihsing fluid accommodated in the hollo~
~i~ cyllnd al member, a pair of contact members disposed in
_ 4 _
. .~,
, . ,~,
,
1~;263~S
the hollow cylindrical member to be relatively movable to
engage and disengage from each other, a reservoir disposed in
the hollow cylindrical member to accumulate the arc-extinguish-
ing fluid increased in pressure due to an electric arc struck
across the contact members separated from each other, a com-
pression chamber disposed in the hollow cylindrical member to
be connected in fluid communication with the reservoir, a
piston movably disposed in the compression chamber and operable
on separation OI the contact members from each other to compress
the arc-extinguishing fluid with the compression chamber and
deliver the compressed fluid to the reservoir, and a nozzle
disposed to be connected in fluid communication with the
reservoir, the nozzle delivering the arc-extinguishing fluid
located in the reservoir and increased in pressure after contact
members are separated by a predetermined distance.
In order to prevent the arc-extinguishing fluid with-
in the reservoir from increasing in both pressure and tempera-
ture, at least one of the contact members or the piston may
be provided with an exhaust passageway permitting the reservoir
to communicate with the exterior of the hollow cylindrical
member therethrough after the separation of the contact members.
This measure is effective for exhausting a portion of the arc-
extinguishing fluid at an elevated temperature into the exterior
of the hollow cylinderical member after the separation of the
contact members. Therefore the interrupting characteristics
for high currents can be improved while those for low currents
are retained.
315 i~
`;
In order to prevent the arc-extinguishing fluid
in the reservoir from rising in temperature abruptly thereby
to cause the fluid put at a low temperature in the reservoir rS
to be remain therein till the interruption of an electric ,~
arc involved, an encircling member may be disposed in the
hollow cylindrical member to encircle the movable contact .
member at its closed position over a predetermined length
measured from a free end thereof. q
In order to control the arc-extinguishing fluid ~,
within the reservoir to a temperature as low as possible ~T
while maintaining a fluid pressure in the reservoir as high
as possible, the exhaust passageway may extend through one
of the contact members or the stationary contact member and
communicate with at least one pair of radial holes disposed r:
on the stationary contact member to be selectively opened and ~
closed in accordance with a distance of movement of the ~r
stationary contact member. This permits the reservoir to
be selectively connected in fluid communication with the
exterior of the hollow cylindrical member.
In order to stabilize the interrupting performance
with a simple, inexpensive driving means, the switch may
include a resilient member for causing the piston to tend ,;
to be forced in a direction of compression of the arc- ,
extinguishing fluid, the resilient member also imparting t~
a separation force to the movable contact member, closing ~i
means for moving the movable contact member toward the ,`
stationary contact member to engage the latter, and locking ~'
means for holding the movable contact member in engagement
with the stationary contact member.
.
- 6 -
;`
11~6315
The movable contact member may be maintained in ,;
engagement with the sta~ionary contact member by coupling
means disposed on free end faces of both contact members, to
be enabled until a trip force with a predetermined magnitude ;
is applied to the coupling means. That trip force is
preferably applied to the coupling means when the piston
reaches its position where the piston completes the operation
of compressing the arc-extinguishing fluid. This measure ;
prevents the piston from being returned bac~ to its initial
inoperative position with the result that the puffer action
is effectively exerted on an electric arc involved to ~s
interrupt the particular current rapidly. Further, upon ;~
passing a current through the stationary contact member !
with the piston resiliently held at its initial inoperative j
position, the stationary contact member is effectively "
prevented from being moved due to an electromagnetic ;
repulsion applied thereto.
The contact members may include a movable contact
member and a stationary contact member fixedly disposed in !3
the hollow cylindrical member. The stationary contact ,7
member serves only to carry a current so that a mechanism for ,
operating the contact members can be simplified while the
fusion and wear and tear of the contact members is reduced.
If desired, the movable contact member may be
maintained in engagement with the piston by coupling means
disposed on engaging portions of the two to be enabled until
a trip force with a predetermined magnitude is applied to
the coupling means. This measure is effective for preventing
the fusion of the contact members without the deterioration
f the interrupting performance. I
- 7 -
63~5
. l .~
Engaging means may be disposed at a position where
the piston completes the compressing operation and abuts
against the engaging means. This measure is effective ~or i,
preventing the fusi.on of the contact members upon their
closure without the deterioration of the interrupting ,
performance.
In order to prevent the piston from being returned ~;
back to its initial inoperation position and interrupt
rapidly the particular current by exerting more effectively
the puffer action on an associated electric arc, a back
pressure chamber for the piston may be disposed in the
compression chamber to be connected in fluid communication
with the exterior of the hollow cylindrical member through
a communication passageway, and a check valve is disposed on
the communication passageway to permit the arc-extinguishing i'
fluid to flow into the back pressure chamber only from the
exterior of the hollow cylindrical member.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more readily
apparent from the following detailed desdription taken in i,~
conjunction with the accompanying drawings in which: t
Figures l and 2 are longitudinal sectional views
of a conventional puffer type switch illustrated at its i1
closed and tripped positions respectively with parts omitted;
Figures 3 and ~ are views similar to Figures l and
2 respectively but illustrating another puffer type switch; b
Figure 5 is a longitudinal sectional view of one
embodiment according to the self-extinguishing type switch 8
- 8 -
Il .
~ 3.~lS
of the present invention illustraed at its closed position r
with parts omitted;
Figure 6 is a view similar to Figure 5 but ~,
illustrating the arranyement of Figure 5 at its tripped
position;
Figures 7 and 8 are views similar to Figures 5 and
6 respectively but illustrating a modification of the
arrangement shown in Figures 5 and 6; f~
Figures 9 and 10 are views similar to Figures 5
and 6 respectively but illustrating another modification of
the arrangement shown in Figures 5 and 6; `.
Figures 11 and 12 are longitudinal sectional views
of a modification of the coupling as shown in Figures ~ and
. 10 illustrated at its closed and tripped positions
respectively;
: Figures 13 and 14 are views similar to Figures 11 !,
and 12 respectively but illustrating another modification i~
of the coupling shown in Figures 9 and 10; .
Figures 15 and 16 are views similar to Figures 9
and 10 respectively but illustrating still another modification
of the coupling shown in Figures 9 and 10; !,
Figures 17 a~d 18 are views similar to Figures 9
and 10 respecti-~ely but illustrating a modification of the r'
arrangement shown in Figures 9 and 10;
Figure 19 is a view similar to Figure 17 but
illustrating at its closed position a modification of the
arrangement shown in Figures 17 and 18; K
Figure 20 is a longitudinal sectional view of a r
modification of the present invention illustrated at its
closed position with part omitted; R
_g_
.
1 ~1;263.~5
I
¦ Figure 21 is a view similar to Figure 20 bllt
¦ illustratiny the arrangement of Figure 20 illustrated at its
tripped position;
¦ Figure 22 is a view similar to Figure 8 but ,.
¦ illustrating a modification of the arrangement as shown in :s
¦ Figures 20 and 21 applied to the arrangement sohwn in Figures !C
¦ 7 and 8; rY
¦ Figure 23 is a longitudinal sectional view of
¦ another modification of the present invention illustrated at
¦ its closed position with parts omitted; ..
¦ Figures 24 and 25 are views similar to Figure 23
¦ but illustrating the arrangement of Figure 23 at two different
¦ tripped positions thereof; ~¦
¦ Figure 26 is a view similar to Figure 23 but
I illustrating a modification of the arrangement as shown in
¦ Figures 23, 24 and 25 applied to the arrangement shown in
¦ Figures 7 and 8;
¦ Figures 27 and 28 are views similar to Figure 26
¦ but illustrating the arrangement of Figure 26 at different r~
tripped positions thereof; il
Figures 29 and 30 similar to Figures 20 and 21
respectivel~ but illustrating another modification of the :!
arrangement shown in Figures 20 and 21; :;
Figure 31 is a view similar to Figure 22 but t
illustrating a modification of the arrangement as shown in ,i
Figure 22 at its closed position; s;
Figures 32 and 33 are views similar to Figure 31
but illustrating the arrangement of Figure 31 at different
tripped positions thereof; u
-10-
ll l~
1~63.15
,1
Figures 34 and 35 are views similar to Figure 31
but illustrating different modiEica-tions of the arranc3ement i!
of Figure 31 at their closed position; ,,
Figure 36 is a v.iew similar to Figure 23 bu-t "
illustrating still another modification of the present ~-
invention;
Figure 37 is a view similar to Figure 36 but
illustrating the arrangement of Figure 36 at its tripped
position; i~
Figure 38 is a view similar to Figure 9 but
illustrating at its closed position a modification of the
arrangement as shown in Figures 36 and 37 applied to the
arrangement shown in Figures 9 and 10; t~
Figure 39 is a view simialr to Figure 17 but ~.~
illustrating at its closed position another modification of ~.
the arrangement of ~igure 38 applied to the arrangement shown .
in Figures 17 and 18; ~-i
Figure 40 is a view similar to Figure 9 but
illustrating at its closed position another modification of
the arrangement shown in Figures 9 and 10;
Figures 41 and 42 are views similar to Figure 40
but illustrating the arrangement of Figure 40 at different
tripped positions thereof; .
Figure 43 is a view similar to Figure 40 but
illustrating at its tripped position a modification of the
arrangement shown in Figures 40, 41 and 42; !~
Figures 44 and 45 are views similar to Figure 9 but i~
illustrating at their closed position different embodiment .: I;
of the arrangement shown in Figures 9 and 10;
-,11-
.
I ~ 3~
!;
Figure 46 is a longitudinal sectional view of a
different modification of the present invention illustrated r
at its closed position with parts omitted; ,~
Figures 47 and ~8 are views similar to Figure 46
but illustrating the arrangement of ~igure 46 at its tripped
and open positions respectively;
Figure 49 is a view similar to Figure 46 but ,
illustrating its closed position a modification of the '!
arrangement shown in ~igures 46, 47 and 43; and
Figures 50 and 51 are views similar to Figure 49 Li
but illustrating the arrangement of Figure 49 at its tripped ,~
and open positions respectively. ~!
Throughout the Figures like reference numerals
designate the identical or corresponding components. ,`
DESCRIPTION OF THE PREFERRED E~BODI~1~.NTS 9
Referring now to Figure 1 of the drawings, there
is illustrated a conventional single-pressure puffer type
switch. The arrangement illustrated comprises a puffer ~`
cylinder 1 operatively coupled to a operating mechanism h
(not shown), a movable contact member 2 fixedly disposed in .
an axial portion of the cylinder 1 and an annular puffer ,!
piston 3 slidably fitted into the puffer cylinder 1 to form ;
an annular compression chamber 4 with an apertured bottom of D
the cylinder 1. The piston 3 is fixed at its position
illustrated in Figure 1 b~ means of a supporting member (not
shown). The puffer cylinder 1 has an electrically insulating
nozzle 5 screw threaded into the bottom portion thereof to
defin hereln an arc-extinguishing chamber 6 that, in turn,
- 12 -
3;~S
communicates with the compression chamber ~ through a plurality
of communlcating holes 7 extending through the bottom of the
puffer cylinder 1. A stationary contact member 8 is supported
to a supporting member (not shown) and includes a free end
portion loosely extending through the nozzle 5 until its free
end is normally contacted by the free end of the movable con.
tact member 2 as shown in Figure 1.
When a command trip signal-is received the operating
mechanism (not shown) is operated to move the cylinder 1 and
the movable contact member 2 integral therewith in a rightward
direction as viewed in Figure 1 to separate the movable contact
member 2 from the stationary contact member 8. At that time
an electric arc 9 strikes across both contact members 2 and 8
within the arc-extinguishing chamber 6 as shown in Figure 2
while simultaneously the piston 3 is relatively moved toward
the bottom of the cylinder 1 to compress an amount of an arc-
extinguishing fluid such as sulfur hexafluoride (SF6) disposed
in the cylinder 1. The fluid compressed to a high pressure
blows against the electric arc 6 through the communicating
holes 7 as shown at the arrow in Figure 2 resulting in the
rapid extinction of the electric arc 6.
In conventional single-pressure puffer type switches
such as shown in Figures 1 and 2 the puffer cylinder and the
electrically insulating nozzle interlocking with the interrupt-
ing operation have been large in weight resulting in the dis-
advantage that a high-power operating mechanism is required
to drive them. This disadvantage has been conspicuous parti-
cularly with high capacity switches because
.
r
:1~;26;3iJL5
the compression chamber such as the chamber ~ needs a l~lrge
volume and because heat due to the electric arc increases ,~,
a pressure rise within the compression chamber thereby to
increase a force tending to push back the piston with
respect to the mating cylinder.
Contrary to switches such as described above, it ~:
has been previously proposed to extinguish the electric arc
struck upon interrupting currents, only through the utilization
of the arc-extinguishing fluid expanded with the electric arc
without either the use of means for compressing the fluid
to a high pressure or the compression of the fluid with an
operating force. This measure has been disadvantageous in .
that the particular reservoir having accumulated therein the r~
fluid thus expanded rises excessively in temperature attended
with a reduction in arc-extinguishing performance.
Figure 3 shows another conventional single-pressure ;~
puffer type switch. In the arrangement illustrated in ~,
Figure 3 a puffer cylinder generally designated by the
reference numeral 10 includes a terminal plate 12, a hollow
cylindrical supporting member 13 fixed at one end to the
terminal plate 12 and an electrically insulating member 14
in the form of a hollow cylinder fixed to the other end of ~.y
the supporting member 13. The puffer cylinder 10 is kept ?~3
stationary by means of a supporting member (not shown) and r
the insulating cylindrical member 14 includes an internal
stepped cylindrical space having a large diameter space
portion 14a located on that end portion thereof abutting ~.
against the supporting cylindrical member 13 the other end
portion 14b flared toward its open end and an intermedi2te `S
- 14 _
6315
cylindrical space portion interconnecting both end portions.
A puffer piston 15 is slidably fitted into the large cliameter
space portion 14a oE the insulating member 14 and provided
on that surface thereof remote from the supporting member 13
with a central raised portion forming a contact 15b. That
surface of the puffer piston 15 exposed to an internal
cylindrical space smaller in diameter than the space portion
14a of the supporting member 13 is connected to a guide rod
16 extending through the internal cylindrical space of the
supportin~ member 13 and then slidably extending through a
through hole 12a disposed on the terminal plate 12. The
puffer piston 15, the contact 15a and the guide rod 16 form
a stationary contact member generally designated by the !A
reference numeral 18. ,,
The large diameter space portion 14a includes one
end defined by an annular portion of the end sur~ace of the ,~
supporting member 13 exposed to the space portion 14a and ~
the other end defined by an annular round step 17b radially ~i
inward extending from the inner wall surface of the large ii
diameter space portion 14a and merged into the interface
between that space portion 14a and the intermediate space ,
portion connected to the flaxed portion 14b.
A collector 19 is elected on the terminal plate 12
to abut resiliently against the outer peripheral surface of
the guide rod 16 and a helical spring 20 is disposed within
the internal cylindrical space of the supporitng member 13 l1
and between the terminal plate 12 and the puffer piston 15 ,
to encircle the guide rod 16 and the collector 19. The
helical spring 20 tends normally to force the puffer piston
15 toward the annular step 17b.
1~ ,~-
~ ;3:~5 ~
Then a movable contact member 21 is inserted into
the internal stepped cylindrical space of the insulating
member 4 from the flared end portion 14b until its free end
abuts against the contact 15a of the stationary contact
member 18. At that time the stationary contact member 18 "
is maintained at its position illustrated in Figure 3
against the resilience of the helical spring 20 to hold the ~
puffer piston 15 in engagement to the annular exposed end IJ
portion 17a of the supporting member 13. Under these
circumstances, a compression chamber 22 is formed in the
large diameter space portion 14a of the insulating member 1~
an~ connected in fluid communication with the exterior of the ~,
cylinder 10 through an annular gap formed between the inner
wall surface of the insulating cylindrical member 14 and the ,
outer peripheral surface of the movable contact member 21.
The movable contact member 21 includes the other
end portion slidably extending through a through hole 23a '~
disposed on another terminal plate 23 and operatively coupled ~,
to an operating mechanism (not shown). ~lso a collector 24 b
is disposed on the terminal plate 23 to abut resiliently
against the outer peripheral surface of the movable contact ~
member 21. L
The arrangement of Figure 3 is disposed within an t
enclosure (not shown) to form therebetween a space filled b
with an amount of an arc-extinguishing fluid such as gaseous
sulfur hexafluoride tSF6). Therefore the compression chamber
is filled with the arc-extinguishing fluid. This space is
called hereinafter an "external space" because it is located
ext nally cf the cylinder 10. The terminal plates 12 and 23 ¦
- 16 -
7n
ll ~
ti,3~5
'/~
are suitably fixed to respective stationary members (not
shown) disposed in the enclosure (not shown).
As in the arrangement shown in Figures 1 and 2,
the operatin~ mechanism (not shown) is operated to move the
movable contact member 21 in the rightward direction as
viewed in Figure 3. Since the stationary contact member 18
tends to be moved in the rightward direction by means of the
action of the helical spring 20, the same is moved in that
direction with the movable contact member 21 until the puffer ..
piston 15 abuts against the annular step 17b as shown in
Figure 4. This prevents a further rightward movement of the
piston 15 and therefore the stationary contact member 18.
During this movement the puffer piston 15 is effective for
compressing the arc-extingu.ishing fluid within the compression
chamber 22.
When the movable contact member 22 is further moved
in the rightward direction, both contact members 18 and 22
are separated from each other whereupon an electric arc 25 ~
strikes thereacross within the internal cylindrical space of r;
the insulating member 14 as shown in Figure 4. Upon the
electric arc striking across the separated contact members '.;
18 and 21, the arc-extinguishing fluid exposed to the electric
arc 25 is expanded thereby to raise rapidly a fluid pressure .~
in the compression chamber 22. ,
After having disengaged from the stationary contact
member 18 the movable contact member 21 is relieved of its
load due to the contact member 18 and therefore is rapidly
spaced from the stationary contact member 18 to spread rapidly
the electric arc 25 until the free end of the movable contact
- 17 - S
63~5
l .~'
i,
member 21 reaches the flared portion 14a of the insulating
member 14 to widen the spacing formed therebetween. At
that time, the arc-extinguishing fluid compressed within the
compression chamber 22 is permitted to flow abruptly into the
external space through the now widened spacing to be rapidly
expanded and therefore cooled. Accordingly the electric arc
25 is blown out with the resulting stream of the cooled fluid. .
In the closing operation, the operating mechanism ~:
(not shown) responds to a command closure signal to move the L~
movable contact member 21 toward the stationary contact r
member 18 to engage the former with the latter after which -~
the movable contact member 21 forcedly move the stationary ,.
contact member 18 with the puffer piston 15 in the leftward
direction as viewed in Figure 3 or 4 against the action of .~
the helical spring 20 until the piston 15 is seated on the i.l
annular end surface 17a of the supporting member 13 as shown '~;
in Figure 3. At that time the closing operation is completed.
During the closing operati.on the arc-extinguishing fluid
from the external space is supplied via the spacing bet~7een
the insulating cylindrical member 14 and the movable contact :~
member 21 to the compression chamber 22 to be ready for the .
next succeeding interrupting operation.
In conventional switches such as shown in Figures i.,
3 and 4 the puffer piston 15 is operated over the entire
volume of the compression chamber 22 between the annular end fi
surface 17a and the step 17b so that, upon separating both
contact members from each other, the volume of the compression
chamber 22 becomes extremely small thereby to render a fluid
pressu within the chamber 22 extremely high. This has
- 18 -
~.,
li
~fi3~5
,'i
,,,
resulted in the disadvantages that the helical spring 20 t
is required to be of a high-power type while the closing
operation requires a high power operating mechanism sufficlent
to overcome such a high-power spring and tl~at the arc-
extinguishing fluid within the compression chamber 22 can
not absorbe a large quantity of arc energy emitted into the
compression chamber 22 particularly upon interrupting any
high current while the same remains at its low temperature.
Accordingly, the fluid is deprived of the arc-extinguishing
ability because of an elevated temperature thereof.
Also such switches have been disadvantageous in the r''
following respects:
When the free end of the movable contact member 21
is moved to reach the flared insulating portion 14_, the fluid
from the compression chamber 22 is rapidly delivered because
of an extremely high pressure thereof. ~Iowever, due to the r
small volume thereof, the compression chamber loses
immediately the fluid resulting in a short blast time.
Accordin~ly, in the extreme case, a current can be interrupted
only when the current passes through its zero point within
such a short blast time.
Further it has been difficult to increase the
ability to interrupt low currents and that to interrupt high
currents simultaneously. ~lore specifically, if the volume
of the compression chamber is determined so as to render the ~:
interrupting ability good for low currents then the
interruption of a high current has resulted in the fluid
within the compression chamber being heated and expanded
with a large quantity of energy due to an electric arc
struck across both contact members. This has caused the
_ 1 9 _ ! .
¦¦ r
~ ;3J~
L
l,:
fluid within the compression chamber to be put under a very
high pressure and also at an excessively elevated temperature
resulting in an intense reduction in arc-extinguishing
ability. Accordingly, even though the fluid at the
excessively elevated temperature would blow against the ~;
electric arc, the latter has not heen blo~n out.
Furthermore, with both contact members separated
from each other to strike an electric arc thereacross, the .,
electric arc might further raise the fluid pressure within
the compression chamber enough to overcome the resilience
of the helical spring 20 tending to force the stationary
contact member 18 toward the stationary contact member 21.
Under these curcumstances, the stationary contact member 18 tt~.
has been pushed back with the fluid pressure within the ,
compression chamber thereby to reduce the fluid pressure .,
within the compression chamber and therefore the interrupting
ability.
Also after the opening of both contact members,
the re-closing operation is performed in such a manner that, ,~
upon both contact members 18 and 20 engaging each other, the
stationary contact member receives a high impact force from
the movable contact member so that this impact force
cooperates with the resilience of the helical spring 20
to repeat the alternating disengagement and engagement .
between both contact members until the movable contact il
member ultimately engages the stationary contact member. ~3
That is, in the process terminatinq at this ultimate ,
enaagement the chattering occurs~ and electric arcs
repeatedly strikes across both contact members resulting
in their being fused to each other.
- 20 -
ll ~-
~J~3:~S ,~
Figures 5 and 6 show one embodiment according to I,
the switching device of the present invention at its closed
and tripped positions respectively. The arrangement `~
illustrated is different from that shown in Figures 3 and ~ :,
in that in Figures 5 and 6 the hollow cylindrical, electricall
insulating member 14 illustrated in Figures 3 and 4 is
replaced by a hollow cylindrical metallic housing member 26 ;
including one end open and the other end provided with a
central opening into which a cylindrical electrically
insulating nozzle 27 is firmly fitted.
More specifically, the hollow cylindrical member
26 is fixedly secured at the open end to the hollow cylindrical
supporting member 13 and provided on the open end portion ~`
with a large diameter space 26a defining a compression
chamber 29 with the annular end surface portion 28a of the
supporting member 13 exposed to the large diameter space 26a
and a circumferential round step 28_ disposed on the inner
wall surface of the hollow cylindrical member 26 to be b
spaced from the open end thereof by a predetermined length.
The puffer piston 15 is slidably fitted into the compression )L
chamber 29 to reciprocate between the annualr end surface r
portion 28a and the circumferential round step 28_ serving
as stoppers for limiting the movement of the puffer piston ~1
15 within the compression chamber 29. Therefore the piston ~-
15 includes one peripheral corner nearer to the step 28b
and complementary in shape to the step 28b and the other
peripheral corner shaped into a right angle. ~he remaining
space located within the hollow cylindrical member 26 ,
between the step 28b and the other end thereof forms a
i3~
l ",
~s
reservoir 30 somewhat smaller in diameter than the compression .'
chamber 29 for the purpose as will be subsequently apparent.
The insulating nozzle 27 is substantially similar '.'
to the free end portion of the electrically insulating member
14 shown in Figures 3 and 4 and includes a flared portion
27a simialr to the flared portion 14b as described above. ,~
In other respects, the arrangement is substantially .s
identical to that shown in Figures 3 and 4.
From the foregoing it is seen that the arrangement ~;
shown in Figures 5 and 6 includes the compression cham~er 29
located on that side thereof adjacent to the supporting
member 13 and the reservoir 30 located on the other side q
thereof to be continuous to the compresison chamber 29.
The compression chamber 29 has a volume capable of reducing
substantially to a null magnitude by the puffer piston 15
and the reservoir 30 serves to accumulate the arc-extinguishing
fluid compressed wtihin the compression chamber 29. ~s
As in the arrangement shown in Figures 3 and 4 the
operating mechanism (not shown) is operated to move the v
movable contact member 21 in the rightward direction as .
viewed in Figure 5 which is attended with the similar a
movement of the stationary contact member 18 with the puffer r~
piston 15 resulting from the resilience provided by the -
helical spring 20. This results in the compression of the
fluid within the compression chamber 29.
When the movable contact member 21 is further moved .
in the rightward direction, the puffer piston 15 abuts
against the stopper 28b whereupon the stationary contact
member 18 is prevented from being further moved in the
63~5
rightward direction. Therefore both contact members 21 and
18 are separated from each other resulting in an electric farc 25 striking across both contact members as shown in
Figure 6.
At that time, the volume of the compression
chamber 29 becomes substantiall null while the reservoir 38
accumulates the fluid increased in pressure. However, the ~ctotal volume of the compression chamber 29 and the reservoir ,~30 has a small rate of change so that the fluid pressure
is prevented from rising excessively. Also termal engergy
resulting from the electric arc 25 struck across both contact
members 21 and 18 is utilized to raise the fluid pressure
within the reservoir 30 but due to the large volume of the :reservoir 30, the fluid is prevented from increasing
excessively in both pressure and temperature even upon
interrupting high currents. This means that the fluid .under a high pressure at a sufficiently low temperature tcan be accumulated in a large amount within the reservoir ~`30 for interrupting high currents. ~; Thereafter the process as described above in
conjunction with Figures 3 and 4 is repeated to extinguish ,the electric arc 25. In the arrangement shown in Figures 5
and 6 it is noted that, because of the large volume of the
reservoir 30, the arc~extinguishing fluid increased in ,lpressure within the reservoir 30 can blowagainst the electric ,1arc for a long time interval. This makes it possible to .~interrupt the particular current in the stable manner even 'though the current would pass through its zero point at any
time point. r
_ 23 -
.i
1~ i3:~5
From the foregoing it is seen that the present
invention comprises the compression chamber for compressing
the arc-extinguishing fluid tllerein by decreasing its
volume substantially to a zero magnitude and the reservoir
adjacent to the compression chamber to be put in fluid
communication therewith. Therefore it is possible to
accumulate a large amount of the fluid having a proper
pressure and a low temperature. This results in the ~i
interrupting performance stabilized throughout a current
range of from a low to a high magnitude.
Figures 7 and 8 illustrate a modification of the
arrangement shown in Figures 5 and 6 at its closed and
tripped positions respectively. The arrangement illustrated
is different from that shown in Figure 5 principally in that
in Figure 7, the stationary contact member 18 is disposed
in the reservoir to be connected to the inner wall surface
of the hollow cylindrical member 26.
More specifically, the stationary contact member 18
includes a hollow disc-shaped case 18a provided on the
opposite surfaces with central aligned apertures and .
coaxially disposed within the reservoir 30 to be connected
to the inner wall surface of the latter. Disposed in the
case 18a is a split contact 18b having an inside diameter
sufficient to permit the movable contact member 21 to extend
therethrough and normally biased toward the central axis of
the case 18a by leaf springs 18c disposed between the outer
peripheral surface of the split contact 18 and the inner
wall surface of the case 18a. As shown in Figure 7 the
movable contact member 21 at its closed position extends
i315
,:
through the split contact l~b to be put in good enyagement
with the latter by means o~ the action of the springs 1~_.
Further the movable contact memher 21 at its closed position
has its free end somewhat producing from the case 18a to
engage a slider generally designated by the reference
numeral 150. The slider 150 is identical in both shape ,.
and operation to the stationary contact member 18 shown in
Figures 5 and 6 excepting that no current flows through the
slider 150. Therefore the slider 150 is formed of an
electrically insulating material and the collector 19
shown in Figures 5 and 6 is omitted in Figures 7 and 8.
In other respects the arrangement is substantially
identical to that shown in Figures 5 and 6.
Accordingly it will readily be understood that
the arrangement of Figure 7 is substantially identical in
operation to that shown in Figures 5 and 6 exdept for an
electric arc 25 striking across the free end of the movable
contact member 21 and the inner peripheral surface of the
split contact 18_ as shown in Figure 8.
Since the slider 150 does not form a current- ~,
carrying path and the associated collector is omitted, the
same bears no contact pressure due to the collector. 1,
Accordingly there are not caused a drag due to such a
contact pressure and a repulsion resulting from a current
which will otherwide flow through the slider. This permits
the helical spring 20 to reduce in resilience. Further the
chattering can be avoided because the stationary contact
member 18 is located so as not to be struck by the movable
contact member 21. This results in a reduction in wear and
- 25 -
,1~ .
~ fi3~5
tear of the contact members caused from electric arcs struck
thereacross. ',
The electrically insulating nozzle 27 way include
its cylindrical hole increased in diameter and the stationary
contact member lg is disposed in this large diameter hole.
The slider 150 may be partly or entirely formed
of a metallic material.
Figure 9 shows a modification of the present r
invention. In the arrangement illustrated the puffer
cylinder 10 or the hollow cylindrical member 26 includes
the large diameter space portion 26a disposed in the axially
middle portion. An apertured terminal plate 12 in the form
of a disc closes one end, in this case, the upper end as
viewed in Figure 9 of the cylinder 10 and an electrically
insulating nozzle 27 similar to the nozzle 27 as shown in
Figures 5 and 6 screw threaded into the other or lower end
portion thereof.
As tationary contact member 18 is substantially
identical to that shown in Figures 5 and 6, and has a puffer
piston 15 slidably fitted into the large diameter portion
26a forming a compression chamber 29 to reciprocate therein
between a pair of circumferential flat steps 28a and 28b.
The stationary contact member 18 includes an arm portion
slidably extending through a central hole on the terminal i'
plate 12 and engaging a collector 19 disposed on the inner
surface of the terminal plate 12 with a helical spring 20
as shown in Figures 5 and 6 omitted. Therefore the stationary
contact member 18 is electrically connected to an external
electric device through the collector 19 and the terminal
plate
The puffer piston 15 partitions the interior of
the puffer cylinder 10 into a pair of upper and lower
chambers 31 and 30 respectively equal in diame-ter to each
other and somewaht smaller in diameter than the large diameter
space portion 2~a. The upper chamber 31 communicates with ,
the arc-extinguishing fluid disposed in the external space ;?
through a plurality of holes 32 extending through the
terminal plate 12. The lower chamber includes the compression
chamber 29 formed of the large diameter space portion 26a
and the reservoir 30 continuous to the compression chamber 29. r
The puffer cylinder 10 is held at its position ~
illustrated in Figure 9 by a supporting member (not shown) :
where the puffer piston 15 abuts against the upper step 28a. ~
A movable contact member 21 operatively coupled to ~'
an operating mechanism (not shown) slidably extends through
an axial hole of the insulating nozzel 27 similar to that
shown in Figures 5 and 6 to engage the stationary contact
member 18 at its closed portion.
As shown in ~igure 9, a central raised portion 15a
of the puffer piston 15 includes a tulip-shaped contact 33
pendent from the end thereof and tapered toward its end while
the movable contact member 21 is provided on the free end
portion with a recess 34 in the form of a bottle. At the
closed position the stationary contact member 18 detachably
engages the movable contact member 21 by having the tulip-
shaped contact 33 resiliently inserted into the bottle-shape
recess 34. Therefore the tulip-shape contact 33 forms a
snap hook type coupling with the bottle-shaped recess 34.
This coupling is maintained in engaging state until it r
r
~1~31 ~i3~5
l ~.'
receives a force, in this case, a trip force of a predetermined l~
magnitude. For the trip force in excess of the predetermined
magnitude the contact 33 oE the coupling disengages from the t
recess thereof.
As in the arrangement of Figure 5, the operating
mechanism (not shown) is operated to move the movable contact
member 21 downward as viewd in Figure 9. As the tulip-
shaped contact is maintained in engagement with the bottle-
shaped recess 34, the stationary contact member 18 is also
moved downward with the moving contact member 21 to cause the
piston 15 to compress the fluid disposed in the compression r
chamber 29 and the reservoir 30. When the piston 15 abuts r
against the lower step 28b on the large diameter space
portion 26b, the stationary contact member 18 is prevented r~
from further descending while the movable contact member
continues to descend. As a result, a trip force in excess t~
of the predetermined magnitude as desdribed above is applied
to the coupling 33-34 to cause the contact 33 to disengage
from the recess.34 resulting in the separation of both ..
contact members 18 and 21. At that time an electric arc
25 strikes across both contact members as shown in Figure 10.
Thereafter the process as described above in r
conjunction with Figures 3 and 4 is repeated to extinguish .,
the electric arc 25
From the foregoing it is seen that, since the t
operating mechanism (not shown) is required only to operate
the stationar~ contact member 18 including the puffer piston
15 and the movable contact member 21, it is able to render
the weight of operated components small as compared with the
- 28 -
. ,, .~
ti315
''~
prior art practice. In addition, in the duration of tlle
electric arc for whlch a speed of separation of the movable i-
contact member 18 is required to hold at the highest
magnitude, it is sufficient to operate the movable contact
member 21 alone. Therefore the speed oF separation can be
sufficiently high with a force provided by a low-power
operating mechanism. Accordingly the interrupting performance s
can be improved with a small-sized, inexpensive consturction. ~
While the arrangement of Figure 9 includes the 5
tulip-shaped contact 33 formed of an electrically conductive
material, it is to be understood that the contact 33 may be
formed of an electrically insulating material. In the latter
case, the re-engagement of the contact 33 with the recess 34
does not result in a current flowing therethrough upon the
engagement. This causes a reduction in fear that an
electric arc will strike across the two upon the engagement
resulting in their fusion. Therefore the use of the ,~
electrically insulating contact 35 is advantageous for high
rated current circuits.
The coupling as described above may be modified
as shown in Figures 11 and 12. In the arrangement illustrated
the stationay contact member 18 is provided on the free end
surface portion with a hook-shaped depression 36 having a
contracted portion located adjacent to its mouth to be
sufficient to permit the recessed end portion of the movable i~
contact member 21 as shown in Figure 9 to be resiliently
inserted into the depression 36 as shown in Figure 11. The
tulip-shaped contact 33 is diposed at the bottom of the
dep sion 36 and resiliently inserted into the recess 34
- 29 -
i315
at its closed position. Figure 12 shows the free end portions
of both contact members 18 and 2] a-t their tripped positions.
In the arrangement shown in Figures 11 and 12, an electric
arc strikes across the free ends of both contact members 18
and 21 so that the contact 33 is prevented from being exposed
to the electric arc.
Also, as shown in Figures 13 and 14, the depression
36 can be provided on the inner peripheral surfade with a
pair of diametrically opposite notches in which a pair of
engaging members 37 formed of an electrically conductive
material are disposed in diametrically opposite relationship
with the tulip-shaped contact 33 omitted. Then a leaf spring s
38 is interposed between each engaging member 37 and the
mating notch to bias normally the engaging element in a
radially inward direction.
On the other hand, the movable contact member 21 j~
includes a pair of diametrically opposite notches 39 r
located at their positions where the notches 21 engage the
respective engaging members 37 when both contact members 18
and 21 engage each other as shown in Figure 13. To this end,
the notch 39 is complentary in shape to the mating engaging .~
member 37. ii
Figure 1~ shows the free end portions of both ,l
contact member 18 and 21 at their tripped positions. ~d
In Figures 15 and 16, the stationary contact
member 18 has the free end portion shaped into a depression
similar to that shown in Figure 11, that is, having a ,
contracted portion ~0 located adjacent to its mouth while
the free end portion of the movable contact member 21
~ 30 ~
~,
lt
~1;2fii3.~L5
r~
includes a circumferential swelled portion 41 sufficient to
pass resiliently throu~h the contracted portion 40 and tapered
toward the free end substantially equal in diameter to the ~:~
main body of the movable contact member 21. As shown in
Fi~ure 15, the free end of the movable contact member 21 at I~r
its closed position rests at the bottom of the depression on ,~
the stationary contact member 18. Figure 16 shows the free
end portions of both contact members 18 and 21 at their ,~
tripped positions. The arrangement shown in Figures 15 and
16 is advantageous over the arrangements shown in Figures 9,
10, Figures 11, 12 and Figures 13, 14 in that both free end
portions are prevented from easily disengaging from each !l
other without an additional component or components assembled
into the stationary contact member 18.
The arrangement illustrated in Figure 17 is different i~
from that shown in Figure 9 principally in that in Figure 11, ,1
the stationary contact member is disposed within the resevoir q
30. More specifically, a pair of stationary contact members
18 are disposed in diametrically opposite relationship within
the reservoir 30 by having their bottom located in associated
notches disposed also in diametrically opposite relationship n
on the inner wall surface of the reservoir 30. Then a leaf
spring 42 is disposed in the mating notche to bias normally
the associated stationary contact member 18 in the radially ~;'
inward direction. Therefore, at their closed position the .;~
stationary contact members 18 are put in sliding engagement
with the outer peripheral surface of the movable contact
member 21 as having extended past the same (see Figure 17).
Further the tulip-shaped contact 33 is directly screw threaded
- 31 -
13~;2fi3~5
into the surface of the puffer piston 15 with the central
raised portion thereof (see Figure ~) omitted, and the
compression chamber 29 reaches to the terminal plate integral ,~
with the cylindrical member 26. Therefore, the upper chamber
31 (see Figure 9) is omitted. Because the stationary contact
members 18 are disposed within the reservoir 30, the piston
15 and the guide rod 16 therefor forms an arc contact member
150 and also serves as the slider 150 as described above in L;
conjunction with ~igure 7. Therefore, the collector 19
(see Figure 9) is omitted.
In other respects, the arrangement is substantially
identical to that shown in Figures 9 and 10.
In the opening operation 17, the tulip-shaped r
contact 33 on the piston 15 first disengages from the recess
34 on the movable contact member 21 after the piston 15 has
reached the lower step 28b. Then the movable contact .`
member 21 disengages from the stationary contact members 18 ,~
to cause an electric arc 25 as shown in Figure 18. .,
In the closing operation, the movable contact r.
member 21 is moved upward as viewed in Figure 13 to fit the
free end portion thereof into the spacing between the opposite
stationary contact members 18 to engage it with the latter
at that time, a current flows through both contact members
18 and 21 after which the movable contact member 21 abuts ,,
against the piston 15 to force it upwardly until the piston
15 abuts against the step 28a on the terminal plate 12 to
be prevented from ascending. At that time the tulip-shaped
contact 33 on the piston 15 resiliently forced into the rr
recess 34 on the movable contact member 21 to be returned
't
,,
- 32 - '~
fi;~5
back to its original position as shown in Figur~ 17.
In Figures 17 and 1~ the stationary and movable con-
tact members 18 and 21 respectively are shown as haviny respec-
tive contacts attached to the free ends thereof. However, in
the foregoing Figures and some of the subsequent Figures,
those contacts are omitted only for purposes of illustration.
Also in some of the subsequent Figures such contacts are
illustrated without the reference numerals identifying the same.
In Figure 19, the tulip-shaped contact 33 increases
in axial length while the recess 34 increases in depth corres-
pondingly. ~lso a clearance 32' is formed around the guide
rod 16 for the piston 15 within the central hole on the terminal
plate 12 to be substituted for the through holes 32 as shown
in Figure 17.
In other respects, the arrangement illustrated is
identical to that shown in Figure 17.
In Figure 19 it is seen that the tulip-shaped end
portion of the contact 33 on the stationary contact member 18
can disengage from the recess 34 on the movable contact member
21 immediately after both contact members have disengaged from each
other and an electric arc has been struck thereacross. This '~
permits a reduction in extent to which the puffer piston 15
tends to be moved away fxom the movable contact member 21 by
means of the pressure of the compressed fluid upon the contact
33 disengaging from the recess 34. Accordingly, the more
effective puffer action can be expected.
- 33 -
:
6~5
The arrangement of E'igure 5 can be modifi~d as
shown in Figure 20. In Fiyure 20, the stationary contact
member 18 includes an axial exhaust passageway 18A extending
throughout its length and,axially aligned with an axial
exhaust passageway 18B similarly extending throughout the ,,
length of the movable contact member 21. Both exhaust
passageways 18A and 18B serve to cause the compression
chamber 29 to be connected in fluid communication with the
external space therethrough. ~Iowever, with both contact ,,
members engaged by each other, the compression chamber 29 ;~
is prevented from communication with the axial exhaust ,i
passageways 18A and 21A. !2
The movable contact member 21 is separated from ,-
the stationary contact member 18 in the same manner as ~.
described above in conjunction with Figure 5. At that
time an electric arc 25 strikes across both contact members
18 and 21 while the compression chamber 29 communicates with
the external space through the axial exhaust passageways
18A and 21A as shown in Figure 21. Under these circumstances, l'
the are-extinguishing fluid compressed in the reservoir 30
is exhausted into the external space through the passageways t.
18A ~nd 21A while it cools the electric arc 25. For a low
interrupted eurrent, the electrie arc 25 ean be extinguished
only by means of the eooling action due to the blast of that
eompressed fluid.
For a high interrupted current, however, the
resulting electrie arc 25 has a large diameter sufficient
to close the exhaust passageways 18A and 21A. Therefore, ~'
a fluid pressure in the compression chamber 29 is not ~:
ll
. ~ 3~5
.
lowered and inversely is raised because thermal energy due
to the electric arc 25 is partly accumulated in the reservoir
30. However since one portion of the fluid is exhausted ':
into the external space through the exhaust passageways 18A
and 21A, the fluid within the reservoir 30 is prevented from
increasing in both pressure and temperature excessively.
When the free end of the movable contact member 21
enters the flared portion 27a of the electrically insulating -
nozzle 27, the fluid from the reservoir 30 is rapidly
discharged to the external space as in the arrangement shown
in Figures 5 and 6. The fluid thus discharged has a
relatively high pressure and a relatively low temperature
which cooperates with a large opening area of the nozzle 27
to permit a large amount of the ~luid to blow against the
electric arc 25. As a result, the electric arc 25 is
satisfactorily cooled and extinguished even though the
particular interrupted current would be high.
From the foregoing it will readily be understood ;
that, after both contact members 18 and 21 have disengaged
from each other, low currents can be rapidly interrupted
by means of the piston action of the puffer piston 15 combined
with the axial exhaust passageways 18A and 21A extending
throughout the stationary and movable contact members 18 and
21 respectively. Also upon interrupting high currents, the
fluid increased in both pressure and temperature due to the
resulting electric arc is partly exhausted through the
exhaust passageways 18A and 21A immediately after the
occurrence of the electric arc. This to permits the
interior of the reservoir 30 to be prevented from increasing
! ~63~5
ti'
in both pressure and temperature excessively. ThereaEter t~
the free end of the movable contact member 21 enters the
flared portion 27a of the insulating nozzle 27 whereupon the
fluid having the sufficient arc-extinguishing performance
can blow against the electric arc. This can smoothly cool
and exhaust the electric arc.
Also since the contact member includes the axial t
exhaust passageway, the convention is apt to occur when a
current flows through the contact member. Where the exhaust ;
passageway extends through each of the stationary and movable
contact members as in the arrangement of Figure 21, the t
effect of this convection is particularly conspecuous.
In summary, the arrangement shown in Figures 20 ~
and 21 can realize the interrupting performance excellent ~Z
concerning to both low and high currents with a simple,
inexpensive construction and still increase a current
flowing through the stationary and movable contact members.
The arrangement illustrated in Figure 22 is
different from that shown in Figure 7 in that the slider
150 is formed of a metallic material to form an arc contact
member as in the arrangements shown in Figures 17 and 18 and
that axial exhaust passageways 150A and 21A extend throughout
the length of the arc and movable contact members 150 and
21 respectively.
Figure 23 shows another modification of the present
invention. The arrangement illustrated is different from
that shown in Figure 5 only in that in Figure 23, an
encircling member is disposed to encircle the free end
portions of the stationary and movable contact members and
'Z
_ 3~ _
1~ .
~ 5
'.,
the stationary contact member includes the axial exhaust
passageway extending throughout the length thereof. More '
specifically, the encircling member 42 includes an apertured
partition 42a fixed at the outer periphery to a radially
inward directed circumferential rib located on the inner !'
wall surface of the hollow cylindrical member 26 between ~.
the compression chamber 29 and the reservoir 30 equal in
diameter to each other. That lateral surface of the rib
facing the piston 15 forms the circumferential step 28b or
the stopper for the piston 15.
The encircling member 42 includes a relatively
short sleeve 42_ extending from the central portion of the t-
partition 42a toward the nozzle 27 and the partition 42a ij
includes a plurality of radial openings disposed at ,.
predetermined equal angular intervals thereon to extend ~
from the outer periphery of the sleeve 42b to the outer edge b
of the partition 42a (only one of which is illustrated)
thereby to put the compression chamber 29 in fluid
communication with the reservoir 30. The encircling member
42 is formed of an electrically insulating material. ~:
The sleeve 42b is so dimensioned that the ;
stationary and movable contact members 18 and 21 respectively
can be inserted thereinto with a minute clearance formed
therebetween as shGwn in Figures 23 and that the free
end of the stationary contact member lg reaches very short
of that end of the sleeve 42b nearer to the nozzle 27 upon
the completion of the interruption as shown in Figure 24. 'c
At their closed position, both contact members 18 and 21
engage each other within the sleeve 42b adjacent to the other P
end thereof. ~
- 37 - a
?;J
~3~
1~
~ S3.~5
..
Therefore the sleeve 42b can encircle the
stationary contact member 18 over a predetermined length ,
measured in a direction of separation of the movable
contact member 21 to the free end thereof.
The encircling member 42 serves to permit the
arc-extinguishing fluid within the reservoir 30 to be .~.
delivered to the external space only after fluid has ~t
penetrated the electric arc and to retain a low temperature
fluid in the reservoir 30 w'lile the fluid in the reservoir .~
30 is prevented from increasing in temperature. In addition ,
the encircling member 42 is effective for blowing axially
the low temperature fluid that has been accumulated in the
reservoir 30 by the piston 15 even when the chattering r;,~
occurs between both contac, members 18 and 21 to strike
electric arcs thereacross while the piston 15 is not engaged
by the step 28_ due to a weak resilience of the helical ,~
spring 20 (see Figure 25). ,_
Therefore, when the fluid within the reservoir 30 ,,,
increase ln pressure by expanding the same through the
utilization of an electric arc struck upon interrupting the .
particular current, a temperature rise in the reservoir is
limited by the partition defining the boundary between the
reservoir and aspace where the electric arc strikes. This
results in an increase in arc-extinguishing ability to L
interrupt electric arcs. ! 3
The arrangement illustrated in Figure 26 is t~,
different from that shown in Figure 22 principally in that l~
in Figure 26 an encircling member similar to that shown in ~,
Fig e 24 is disposed within tbe h~llow cylindrical member 26.
. .. ,
_.
.
,.
~ ~ l~
More specifically, the encircling member 42 is fixed to the
inner wall surface of the hollow c~lindrical member 26
substantially identical to that shown in Figure 24 in the
same manner as descri.bed above in conjunction with Figure 24 :;
excepting that its sleeve 42b is connected to the stationary
contact member 18. The sleeve 42b is axially aligned with .
the through hole in the stationary contact member 18 having :
a diameter slightly smaller than the inside diameter of the
sleeve 42b.
The slider or the arc contact member 150 has its
free end portion reduced in diameter and adapted to be ,~
located within the sleeve 42b at the closed position as L
shown in Figure 26. Upon an electric arc 25 striking across
both contact members 21 and 150 with the piston 15 abutting
against the step 2~b as shown in Figure 27. That portion of ...
the contact member 150 following the reduced end portion has
a predetermined length encircled by the sleeve 42 . ,.~
Figure 28 shows the slider or arc contact member ,:
15 not flowing up the movement of the movable contact member
21 due to a weak resilience provided by the helical spring 20.
The encircling member 42 or the sleeve 42b plays its role in
preventing the arc-extinguishing fluid in the reservoir 30
from escaping to the external space until the fluid is
completed to be compressed within the reservoir 30 through
the movement of the piston 15 and in retaining the fluid at
a low temperature in the reservoir until the electric arc
is completed to be interrupted. Of course, the fluid from
the reservoir 30 is permitted to be delivered to the external
space only after it has penetrated the arc until the free ~
- 39 - ~,
.
' .... ~,
3:~5
.,
I ~`
end of the movable contact member 21 passes through the
flared portion 27a of the nozzle 27.
Figure 29 illustrates a modification of the
arrangement shown in Figure 20. The arrangement illustrated r~
is different from that shown in Figure 20 only in that in ,~
Figure 29 the axial exhaust passageway 18A extending through
the stationary contact member 18 is selectively connected
in fluid communication with the external space through at
least two pairs of radial holes maintaining a predetermined
axial distance therebetween. ~ore specifically, the axial s
exhaust passagesay 18A includes a first plurality of radial
holes 18B disposed at predetermited equal angular intervals
in the stationary contact member 18 to be located just under
the terminal plate 12 at the closed position of the stationary
contact member thereby to put the axial exhaust passageway
18A in fluid communication with the exterminal space
therethrough. In Figure 29 a pair of radial holes 18B is
shown as opposing to each other. When the stationary
contact member 18 is moved upward as viewed in Figure 29,
the radial holes 18B are closed with a sleeve 12b sungly
fitted into the opening 12a on the terminal plate 12 to run
toward the puffer piston 15 and form a small clearance
between the sleeve 12a and the stationary contact member 18.
Therefore the axial exhaust passageway 18A is prevented
from communicating with external space.
On the other hand, when the stationary contact r
member lS is moved upward and then stopped through the
engagement of the puffer piston 15 with the step 28b, the
axial passageway 18A is arranged to communicate with the
,,. .
llZ6315
external space through a second plurali-ty of radial holes ,;'
18C disposed in the contact member 1~ in the same manner as lr
the radial holes 18~. To this end, the second pair of
radial holes 18C are located below the first plurality of b
radial holes 18B to form a predetermined distance ~ -
substantially equal to an axial length of the compression
chamber 2~ shown in this case as being equal in diameter
to the reservoir 30. Then an L-shaped closure block 12b
is pendént from the terminal plate 12 so that one leg of the
'IL" is parallel to the latter. That leg is provided with f
a through opening 12c axially aligned with the sleeve 12a ,i
through which the stationary contact member movably extends.
A closed position of the stationary contact member 18, the
second radial holes 18C face the opening 12c adjacent to i,
the bottom of the closure block 12b to be prevente~ from
communicating with the external space as shown in Figure 29
wherein both contact members 18 and 21 are illustrated as
being put at their closed position. That is, the axial
exhaust passageway 18A is not connected in fluid communi- r
cation with the external space. The opening 12c has an axial
length dimensioned so that, when the puffer piston 15 does
not engage the step 28b as shown in Figure 30, the second t
radial holes 18C face the opening 12c to prevent the axial f
exhaust passageway 18A to communicate with the external
space.
The axial exhaust passageway 18A terminals at
the same level as the lowermost wall of the second radial
holes 18C.
- 41 -
1 ~ 6315
,, .
In the interrupting operation the movable contact
member 21 is separated from the stationary contact member
18 to strike an electric arc 25 thereacross within the
reservoir 30. At that time the reservoir 30 communicates
with the external space through the axial exhaust passageway
18A and the second radial holes 18C. If an electric arc
strikes across both contact members 18 and 21 while the former
does not flow up the latter as shown in Figure 30 then the
reservoir 30 does not cor~muncate with the external space and
instead the fluid pressure is accumulated within the
reservoir 30 until the puffer piston 15 engages the step
28b. Under these circumstances, if the fluid pressure is
excessively accumulated within the reservoir 30 with a high
arc current then the stationary contact member 18 is moved
away from the movable contact member 21 to reach its lowermost E
position as viewed in Figure 29. In this case, the pressure
within the reservoir 30 is released through the axial exhaust
passageway 18A and the first radial holes 18~.
In the arrangement of Figure 29, the electric arc
struck upon the separation of both contact members is also
utilized to expand the fluid within the reservoir to raise ~'
the fluid pressure therein after which the fluid from the
reservoir is rapidly delivered thereby to cool and extinguish
the electric arc. In addition, the first and second radial
holes are responsive to the movement of the stationary contact
member to communicate and block the reservoir with and against
the external space. This permits the reservoir to be prevented
from rising in temperature and to have a sufficient fluid
pressure accumulated therein. Therefore the interrupting
315
'.
.` i,,
performance can be improved. Also the resilience exerted on
the stationary contact member can reduce, and a force for
driving the movable contact member may be low while the ~.
construction is simplified. ~J
The arrangement of Figure 22 can be modified in ~.
the same manner as described above in conjunction with
Figures 28 and 29 resulting in that illustrated in Figure 31.
In the arrangement illustrated, the slider 150 also serving !-;
as the arc contact member is identical in construction to the
stationary contact member 18 shown in Figures 28, 29 and 30
to be substituted for the latter. Therefore an axial
passageway 150A, first radial holes 150B and second radial b
holes 150C correspond to the axial passageway 18A, the first
radial holes 18B and the second radial holes 18C as shown
in Figures 28 and 29 respectively.
Also Figures 31 and 32 show the arrangement at
its closed and tripped positions while Figure 33 corresponds
to Figure 30.
Figures 34 and 35 show two modifications of the
arrangement illustrated in Figures 31 and 32 wherein Figure
34 shows the arc contact member 150 including only the
second radial holes 150C and Figure 35 shows the arc contact
member 150 including only the first radial holes 150B with
the closure block 12b omitted.
The first radial holes 18B or 150B cooperate with
the sleeve 12b to serve as a release valve for releasing a
pressure in response to a large rise of pressure in the
reservoir. On the other hand, the second radial holes 18C
or 150C cooperate with the sleeve 12b to control the
operation o~ an exhaust opening at will in accordance with
_ 43 _
ll
3~5
','
a movable member, which opening exhausts only an electric r
arc at an elevated temperature.
Figure 36 shows still another modification of
the present invention. The arrangement illustrated is
substantially similar to that sho~m in Figures 5 and 6
expecting that in Figure 36 there is provided latching means .
for holding the puffer piston in its position where the piston i~
has completed to compress the arc-extinguishing fluid in -
the compression chamber and therefore in the reservoir. -r
More specifically, the latching means includes a plurality ;r,
of latches 43 disposed at predetermined equal angular
intervals on the inner wall surface of the compression
chamber 29 adjacent to the circumferential step 28b which is
formed of a radially inward directed rib defining a boundary '3
between the compression chamber 29 and reservoir 30 equal tj
in diameter to each other. To this end, a plurality of .
recesses are disposed on the inner wall surface of the
compression chamber 29 at positions coinciding with those
of latches 43 and then the latches 43 are disposed in the rl
respective recesses through leaf springs 44 interposed .
between the same and the bottoms of the recesses. Therefore .
each of the latches 43 tends to be normally forced radially '
inward by means of the action of the mating leaf spring 44
so that it normally protrudes in the radially inward
direction from the inner wall surface of the compression
chamber 29. i~
The latching means also includes a circumferential tC
groove 45 disposed on the peripheral surface of the piston
15 at such a position that, when the piston 15 engages the
.~
3~S
step 28b, the g~oove 45 faces the latches ~3. ~s the groove
a 5 is made complementary in shape to each latch 43, they
are fitted into the groove 44 and resilitnly held in
engagement with the latter. The latches 45 and therefore
the groove 45 are so shaped that the resilience of the
helical spring 20 can easily put the groove 45 in engagement
with the latches 43 while groove 4 5 can not disengage from
the latches 43 unless a force higher than resilience of the
helical spring 20 is applied to the groove 45.
As shown in Figure 36, a receptacle 15a in the form
of a hollow cylinder is fixedly secured to the flat surface ~;
of the piston 15 facing the reservoir 30 at the center.
The receptacle 15a includes a centracted portion near to t;
its mouth to permit the free end portion of the movable
contact member 21 to be forced thereinto. The receptacle
15a acts as a contact attached to the stationary contact
member 18.
In the interrupting operation, the puffer piston
15 engages the step 28b to be prevented from being further
moved while at the same time the groove 45 on the piston 15
engages the latches 43 on the inner wall surface of the
compression chamber. Then the movable contact member 21
disengages from the receptacle 15a to strike an electric arc
25 thereacross as shown in Figure 37. The electric arc 25
causes the fluid pressure in the reservoir 30 to be further
increased thereby to increase a force tending to force the
stationary contact member 18 in the leftward direction as
viewed in Figure 37. However, even though this force would
be higher than the resilience of the helical spring 20, the
i~
i3:~5
stationary contact member 18 is dlsabled -to be moved leftward
as viewed in Figure 37 because the groove 45 is in engagement
with the latches 43 to hold the stationary contact member 18
to be maintained fixed to the hollow cylindrical member 26.
Therefore the reservoir 30 can be maintained under a high
fluid pressure.
When the fluid pressure in the reservoir 30 increases
beyond a fluid pressure sufficient to extinguish the electric
arc, the groove 45 disengages from the latches 43 to move the
stationary contact member 18 toward its original position
against the resilience of the helical spring 20. This prevents
the fluid pressure in the reservoir 30 from increasing unnec-
essarily. Upon the fluid pressure within the reservoir 30
reducing, the stationary contact member 18 is again moved
rightward until it is again locked by the latching means 43,
44, 45.
Thereafter the movable contact member 21 is further
separated from the stationary contact member resulting in the
extinction of the electric arc as described above.
When the movable contact member 21 at its open posi-
tion is moved to engage the contacts 15a on the stationary
contact member 18, a current immediately flows through both
contact members to generate an electromagnetic repulsion there-
between. Under these circumstances, the groove 45 on the
piston 15 is in engagement with the latches 43 to prevent the
stationary contact member 18 from moving leftward as viewed
in Figure 37. Accordingly, both contact members are not
separated from each other so that no electric arc strikes there-
across. Accordingly the movable contact
- 46 -
i,
~ ~ i31S
l ~,
member 21 and the contact 15a on the st~tionary contact
member 1~ are prevented from fusing to each other due to
an electric arc struck thereacross
Then the free end of the movable con-tact member 21
is forced into the receptacle 15a after which the movable
contact member 21 is pushed in the le~tward direction as
viewed in Figure 37. This causes the grooves 45 to disengage
from the latches 43 thereby to permit the moved components
to be returned back to their original positions as shown
in Figure 36.
While the stationary contact member 18 is formed t'
integrally with the piston 15, it is to be understood that, '1
as shown in Figure 7, the stationary contact member 18 in ,,
the form of a split contact may be annulus and disposed in
the reservoir 30 and slidably engage the outer peripheral
surface of the rnovable contact member. Further the latching
means is not required to be disposed on both the piston 15 Y
and the compression chamber 29 but it may be disposed on
the guide rod for the piston 15 and that portion of the
terminal plate 12 slidably engaged thereby.
In the arrangement shown in Figures 36 and 37, the ,
puffer piston can be held in its posltion where the piston
has just completed to compress the arc-extinguishing fluid.
Therefore the piston is prevented from retrograding forcedly Y
resulting in improvements in the interrupting performance.
In addition, both contact members in the clsoing process
are prevented from being again separated from each other
due to an electromagnetic repulsion generated therebetween
resulting in an increase in current capacity. Therefore, a
:1
- 47
~ 3~5
the resulting device is small-sized inexpensive an~ hic3h
in current capacity as compared with the prior art practice.
The arrangement illustrated in Figure 38 is
different from that shown in Figure 9 only in that in Figure
38 latchina means including latches 43, leaf springs 44 and
a groove 45 is disposed in the same manner as described above
in conjunction with Figure 36 with the receptacle 15a f
omitted.
The arrangement illustrated in Figure 39 is different
from that shown in Figure 17 only in the same respect just
described in conjunction with Figure 38.
The arrangement illustrated in Figure 40 is
different from that shown in Figure 9 principally in that
in Figure 40, a check valve is operatively coupled to each
of through holes on the terminal plate through which the
stationary contact member slidably extends. As shown in
Figure 40, the check valve designated by the reference
numeral 46 includes a valve body 46a normally closing an
open end of an associated one of the through holes 32 on
the terminal plate 12 facing the chamber 31 now called a
"back pressure chamber" and a valve stem 46b connect at one
to the valve body 46a to extend boosely through the
associated hole 32 and having the other end portion protruding
beyond the terminal plate 12. The other end portion is folded
into a "L" forming a stopper 46c for preventing the check
valve from falling into the back pressure chamber 31.
Also a receptacle 15a such as shown in Figure 36
is fixedly secured to the puffer piston 15 in the same manner
as described above in conjunction with Figure 36.
'~
,,
,~,
- 48 - ,
l ~ 63~5
In other respects the arrangement is identical
to that shown in Figure 9.
When the movable contact memher 21 is descending
with the stationary contact member 18 to compress the arc-
extinguishing fluid in both the compression cha~ber 29 and
the reservoir 30, the check valves 46 open the associated
through holes 32 due to a pressure difference between the ,
external space and the back pressure cham~ier 31. Therefore
the fluid pressure in the back pressure chamber 31 does not
impede the descent of the piston 15 and others.
Then the piston 15 abuts against the step 28b
as shown in Figure 41 until the recess 34 on the movable
contact member 21 disengages from the tulip-shaped member
33, in this case, formed of an electricall~ insulating
material. Also the movable contact member 21 is separated
from the stationary contact member 18 resulting in an
electric arc striking thereacross. This electric arc is
operated to increase further the fluid pressure in the
reservoir 30 until the piston 15 is forced to retrograte.
This results in the closure of the check valves 46. Therefore
the fluid pressure in the back pressure chamber 31 increases
to suppress the retrogradation of the piston 15. As a
result, the reservoir 30 is maintained under a high fluid
pressure.
Thereafter the movable contact member 21 reaches
its position illustrated in Figure 42, and then the electric
arc 25 is blown out with a stream of the arc-extinguishing
fluid designated at the arrows a side the electric arc 25.
As shown also in Figure 42, the electric arc 25 spreads
- 49 -
~1~6315
across the ends of both contact members 21 and 18 so that
the tulip-shaped member 33 is prevented from being directly
exposed to the electric arc 25.
From the Loregoing it is seen that the check
valves are disposed to suppress the retrogra~ation of the
piston. Therefore it is possible to perform the puffer
action more effectively resulting in improvements in
interrupting performance. ,
The arrangement illustrated in Figure A 3 is
different from that shown in Figures 40, 41 and 42 only in
that in Figure 43 a pair of stationary contact members are ~
disposed in diametrically opposite relationship within the t,
reservoir while the stationary contact member 18 shown in
Figures 40, 41 and 42 serves as a slider or arc contact !~
member with the receptacle 15a on the piston 15 omitted. t'
In the arrangement illustrated a pair of recesses are
disposed in diametrically opposite relationsip on the inner
wall surface of the reservoir 30 and have inserted thereinto t
respective stationary contact members 18. The stationary t
contact members 18 tend to be radially inward moved by means
of the action of mating leaf springs 42 interposed between
the same and the bottoms of the associated recesses.
Therefore both stationary contact members 18 are arranged F
to engage slidably the outer peripheral surface of the
movable contact member 21.
The arrangement illustrated in ~igure 44 is
different from that shown in Figures 41, a2 and 43 only in
that in Figure 44 a tension spring 47 is disposed around the t
stationary contact member 18 between the puffer piston 15
- 50 -
~63:~S
f
and the terminal plate 12 by having hoth ends suitably
fixed to the two with the checK valves 46 and the through
holes 32 omitted. The tension spring 47 serves to hold the
piston 15 and therefore the stationary contact member 18 IJ
in the inoperative position illustrated in Figure 44. -
The piston 15 along with the stationary contact
member 78 and the movable contact member 21 is moved downward
as viewed in Figure 44 against a tension provided by the
tension spring 47 to compress the arc-extinguishing fluid r,
in both the compression chamber 2~ and the reservoir 30
after which an electric arc struck cross the movable contact
member 21 and the receptacle or the contact 15a on the ,
stationary contact member 18 is extinguished as described ;
above.
It is noted that, after the tulip-shaped member
33 on the stationary contact member 18 has disengaged from -3
the recess 34 on the movable contact member 21, the puffer 'i~
piston 15 receives not only the tension of the tension spring ,J
47 but also a pressure due to the arc-extinguishing fluid ~
compressed by the piston 15 thereby to tend to be returned ;J
back to the ter~inal plate 12. ~owever, since the puffer
piston 15 has a null initial speed at the beginning of this
return-back and the tension spring 47 is required only to
provide a low tension, the piston 15 is forced to be moved
toward the terminal plate 12 by a very small distance until r
the electric arc is extinguished.
Accordingly, an increase in volume of the reservoir ~
30 results in the fluid pressure therein and hence an amount b
of the fluid blowing against the electric arc being reduced
to a substantially negligible extent. l
- 51 - 3
~,
, ~,
~63:~5
It will readily be understood that the tension i~
spring 47 aids in returning the piston 15 back to its ~,'
inoperative position.
While an electromagnetic repulsion is generated
between the movable and stationary contact arms 21 and 18 .
upon the two engaging each other, the same is disabled to
move the stationary contact member 18 toward the terminal
plate 12 because the piston 15 is in engagement with the ,
step 28a. ~herefore the stationary contact member 1~ can
not be separated from the movable contact member 21. This t
prevents an electric arc from striking across both contact
members. Accordingly, both contact members are not fused
to each other with the result that the tulip-shaped member
33 is permitted to be smoothly inserted into the recess 34.
While the arrangement of Figure 44 utilizes the
tension of the tension spring, a helical spring 48 may be ,
disposed around the movable contact member 21 put at its
closed position in both the compression chamber 29 and the
reservoir 30 as shown in Figure 45. In the latter case, ~,
a resilience provided by the helical spring 48 is utiliæed
to attain the same purpose as the tension of the tension
spring 47.
Figure 46 shows a different embodiment of the
present invention. In Figure 46, the arrangement similar
to that shown in Figures 5 and 6 includes the terminal plate
23 closing an opened of an enclosure 49 and the movable
contact member 21 put at its closed position to be engaged
at the other end by locking means generally designated by ;~
the reference numeral 50 aDd disposed in the enclosure 49.
- 52 -
,
1 ~ i3~S ;;
~ 't
The locking means 50 includes a locking memeber 50a shown
in Figure 46 as abutting against the other end of the t`
movable contact member 21 by means of the action of a ~;
spring 50b. T}-us the locking means 50 detachably locks
the movable contact member 21 at its closed position.
At its closed position the other end of t~ne movable
contact member 21 is somewhat inserted into closure driving
means generally designated by the reference numeral 60.
~lore specifically, the closure driving means 60 includes f
a cylinder 60a having an open end and a spring looded piston
60b slidably fitted into the cylinder 60a. The closure ,
driving means 60 is normally put in its energized state by lAi
a lifting member (not shown) and the free end of the movable
contact member 21 at its closed position is located within 1~
the cylinder 60a adjacent to the open end. !'
With the movable contact member 21 engaged by the c
stationary contact member 21, the locking member 50a is
pulled downward as viewed in Figure 46 against the action
of the spring 50b. Therefore the helical spring 20 is ,~
operated to move the stationary contact member rightward
as viewed in Figure 46 with the movable contact member 21
to strike an electric arc 25 across both contact members
18 and 21 in the manner as described above in conjunction
with Figure 3, 4, 5 and 6 as shown in Figure 47. Then the t~,
electric arc 25 is extinguished as described also above. t
At that time, the movable contact member 21 has the free
end spaced from the nozzle 27 and the other end abutting
agains he piston 60b as shown in Figure 48.
llZ6;315
Under these circumstance, the closure driving
means 60 discharges its energy in responce to a command
closure signal. This results in both contact members engaging
each other in the manner as described above in conjunction
with Figures 3 and 4. At that time the movable contact ,~
member 21 engages the loc~ing means 50 to be locked at its
closed position resulting in the completion of the closing
operation. Also the closure driving means 60 is put in its
energized state by the lifting member tnot shown). Therefore -s
the moved components are returned back to their original ?,
position shown in Figure 46. ,1
Since the closure driving means is required only 5
to perform the closing operation, it can be constructed
simply and inexpensively. Also, both contact members are
maintained in engagement with each other under a pressure
by means of the action of the spring so that the contact ,-~
members are possible to carry a high current. Further, in E
the interrupting operation,; both contact members are operated
from each other only after they have reached predetermined -.
positions resulting in the stabilized interrupting E
performance. If the movable contact member has a large
inertia then the same performs stably the separating ~.
operation. This results in the more reliable interruption.
In the arrangement illustrated in Figure 49 a .l
hollow cylindrical stationary member 10 formed of an ti
electrically insulating material includes one end surface, ,
in this case, the lefthand end surface as viewed in Figure
49 provided with a central small hole, an inner cylindrical u
space lOa having a large cross sectional area, and the other '
. v~ 1
- 54 - .'
'~
1 ~ 5
:
.
or righthand end surface provided with a central hole lOb
having a small cross sectional area. This hole lOb is so ,
dimensioned that the movable contact member 21 movably
extends there-through with a small spacing formed therebetween.
The puffer piston 15 or a slider is slidably fitted
into the inner space lOa and tends to be moved toward the
righthand end surface by means of the action of the helical
spring 20 disposed between the lefthand end surface and the
piston 15. `
The terminal plate 12 is extended and sealed
through the peripheral wall of the hollow member 10 to be E
perpendicular to the longitudinal axis of the hollow member
10. The terminal plate 12 defines a boundary between the
compression chamber 29 and the reservoir 30 and forms one
part of the stationary contact member 18 fixedly secured to '
the inner peripheral wall surface of the reservoir. The
stationary contact member 18 includes a leaf spring 18_
disposed in a recess disposed on the radially inner surface
thereof and a contact 18b fitted into the recess and on the
leaf spring 18a. Therefore the contact 18_ slidably engages
the movable contact member 18 put at its closed position by
means of the action of the leaf spring 18a. At its closed
position the movable contact member lS includes one end,
in this case, the lefthand end as viewed Figure 49 engaging
the puffer piston 15 and the other or righthand end ,
somewaht fitted into the cylinder 60a of the closure driving
means 60 and engaging the locking means 60 movably protruding
beyond the peripheral wall of the cylinder 60a. The locking
means 50 serves to lock the stationary contact member 18 at
- 55 -
. n
.1,
31L5 ~
r
its closed position. The closure driving means 60 further
includes a piston 60_ slidably fitted into the cylinder 60_.
As shown in Figure 49 a collector 24 is located t;adjacent to the open end of the c~linder 60a to abut against
the movable contact member 21.
When the locking means 50 is retraced as shown in
Figure 50, the helical spring 20 is operated to move the
piston 15 in the rightward direction as viewed in Figure 49 r
with the movable contact member 21 to compress the arc- ir
extinguishing fluid in the compression chamber 29 and the
reservoir 30 until the piston 15 abuts against the terminal ;;
plate 12 to be prevented from further moving (see Figure 50).
Thereafter, the movable contact member 21 continues to be
moved in the rightward direction due to its inertia. Then
the movable contact member 21 is separated from the stationary
contact member 18 to strike an electric arc 25 thereacross 3
as shown in Figure 50. The electric arc 25 is extinguished
as described above and the righthand end of the movable i~
contact member 21 abuts against the piston 60b of the closure ,
driving means 60 as shown in Figure 51.
In the closing operation, the piston 60b is moved
in the leftward direction manually or with a mechanical ~3
force resulting, for example, from a spring (not shown) to
move the movable contact member 21 in the leftward direction.
The movable contact member 21 engages the stationary contact L
member 18 and then abuts against the piston 15 thereby to 3
receive the puffer action from the helical spring 20 while
the latter accumulates energy. ~7hen the helical spring 20
is completed to accumulate energy, the locking means 50
3~
l ~ i3J,5
engages the righthand end of the movable contact member 21
to lock the contact member 21 at is closed position. Then
the piston 60b is returned back to its original position
whereupon the closing operation is completed. ~hat is, the
moved components are returned bac~ to their pisitions shown ',.
in Figure 49.
From the foregoing it is seen that by providing ;`
the piston or slider and a resilient mernber or the helical
spring for pushing the slider, a simple closure driving
means can be incorporated into a simple, inexpensive switch ,:
to improve its interrupting performance.
While the present invention has been illustrated ,,`
and described in conjunction with several preferred ;~
embodiments thereof it is to be understood that numerous
changes and modifications may be resorted to without departing
from t spirit and scope of the present invention.
.~
- 57 - ~1
