Note: Descriptions are shown in the official language in which they were submitted.
~067~41
1 This invention relates to a puffer type gas-
blast circuit breaker, and more particularly to a circuit
breaker of the type described, which includes a compres-
sion chamber and a suction chamber, and in which a
pressure difference between the compression chamber and
the suction chamber causes an arc extinguishing gas to be
blown against an arc produced between the contac-ts.
A puffer type gas-blast circuit breaker is
known as a small-size, large-capacity circuit breaker of
a simple construction.
A prior art puffer type gas-blast circuit
breaker includes at least one interrupting unit mounted
in a vessel filled with an arc extinguishing gas such as
an SF6 gas of a unitary pressure. The interrupting unit
- 15 includes a pair of contacts which are positioned in
. .
alignment with but in opposed relation to each other and
movable toward and away from each other so as to be
engaged wlth and to be disengaged from each other,
respectively. At least one of the contacts has therein
20 an axial hollow portionf The interrupting unit further ~ -
includes a compression chamber filled with an arc
extingulshing gas, and an suotion chamber. When a pair of
contacts move away from each other, the arc extinguishing
gas in the compression chamber is compressed, and the
25 ~volume of the suction chamber is enlarged. When a pair
of contacts are disengaged from each other, then the
compression chamber and the suction chamber communicate
with each other through the axial hollow portion of the
one contact, so that a pressure difference between the
compression chamber and the suction chamber causes an arc
:.~, ..... .: :. . : : . : ............... . . I .
,.: . .,, . .. ,, , : .. . ... , . . . .. . . ~ . . .
106794~
1 extinguishing gas from the compression chamber to be
directed into the suction chamber so as to be blasted
against an arc produced between the pair of contacts,
thereby extenguishing the arc.
According to the aforesaid prior art puffer type
gas-blast circuit breaker, there may be obtained a large
pressure difference between the compression chamber and
the suction chamber and hence an arc extinguishing gas
may be effectively blown against an arc produced between
the both contacts, and hence an arcing time may be
shortened. However, in the terminating phase of an
opening operation of a pair of contacts, an arc produced
between the both contacts heats an extenguishing gas,
which in turn is introduced into the suction chamber, so
that a pressure in the suction chamber is increased as
compared with the pressure of gas filled in the vessel.
.,:..~: . :.
In the above case, there results lack of pressure aiffer-
ence between the compression chamber and the suction
chamber, so that the~flow veloci-ty of gas being blown
against an arc produced between contacts is lowered.
In case a pressure in the suction chamber becomes higher
than a pressure within the vessel, then a blowing effect
;: :
of an arc ex-tinguishing gas on the arc is impaired, with
the result m g lowered interrupting-performance of the
breaker.
It is an object of the present invention to
provide a~puffer t~pe gas-blast circuit breaker, which
prevents~the pressure rise in a suction chamber to a
~ : : : . .:
level higher than that in a spàce in a vessel? by bringing
0~ the suctlon chamber into an open condition to or
2 -
~: :
~067g4~
1 communication with a space in a vessel, at the terminating
stage of an opening operation of a pair of contacts.
According to the present invention, there is
provided a puffer type gas-blast circuit breaker having
: 5 at least one interrupting unit mounted in a vessel filied
with an arc extinguishing gas of a unitary pressure,
the aforesaid interrupting unit comprising: a pair of
contacts positioned in alighment with but in opposed
relation to each other, and movable toward and away from
each other to be engaged with and to be disengaged from
each other respectively, at least one of the pair of con-
tacts having therein an axial hollow portion, said hollow
portion having an opening in that axial free end of the
aforesaid at least one contact which is opposed to the
; 15 end of the other contact, wherein an arc is established
;~ between said pair of contacts upon disengagement of the
`. pair of contacts from each other;~ a first cylinder and afirst piston within the first cylinder to define a com-
pression chamber filled with an arc extinguishing gas,
; 20 said first piston and cylinder being movable relative to
:
each other in association with the relative movement of
said pair of contacts; an insulating noz~le encompassing
: :
: ~ a free end portion of one of the aforesaid palr of
contacts, and having a throat po~tion in alignment with
a pair of the contacts, the aforesaid throat portion
: ~: being substantially blocked with the other contact, the
~: : insulating nozzle:having an inner peripheral surface which
deflnes a gulde passage by the cooperation of an outer
: peripheral surface of the free end portion of the afore-
said one contact, and the aforesaid guide passage bringing
3 -
.
~6794~
1 the compression chamber through the opening into com-
munication with the axial hollow portion, when the
aforesaid pair of contact are disengaged from each other;
a second cylinder and a second piston within said second
cylinder to define a suction chamber, the aforesaid second
; piston and cylinder being movable relative to each other
in association with the relative movement of said pair of
contacts; a first communicating means for communicating
the compression chamber with the axial hollow portion;
whereby when said pair of contacts are moved away from
each other to be disengaged from each other, an arc
extinguishing gas in the compression chamber is com-
pressed and a volume of the suction chamber is enlarged,
and a pressure difference between the compression chamber
and the suction chamber causes an arc extinguishing gas
to be directed from the compression chamber via the guide
passage, the axial hollow portion, and the first communi-
catlng means into the suction chamber to blow against an
arc produced between the pair of contacts; and gas bleed-
ing means for allowing communication of the suction chamber
; with a space within the vessel for bleeding an arc
extinguishing gas from the suction chamber into the
vessel,~when the pair of contacts move a fixed distance
in the opposite directions away from each other.
According to the circuit breaker of the
: : :
present invention,~both of a pair of contacts may be
relatively moved or one of a pair of the contacts is
movable and the other may be fixed. In addition, a pair
of the contacts may both have axial hollow portions.
30 ~ ~till slternatively, bo-th of the f.lrst cylinder
L~ _
, .
~067~34~
l and the first piston may be moved, or one of them is
movable and the other may be fixed. In this case, one
of them may be allowed to be coupled to a contact.
~ikewise, both of the second cylinder and the second
piston may be ~oved, or one of them is movable and the
other is fixed. In this case, one of them may be allowed
to be coupled to a contact.
Fig. l is a cross-sectional view of a puffer
type gas-blast circuit breaker according to the present
invention, in its closed circuit condition;
Fig. 2 is a cross-sectional vie~ illustrating
a part of the circuit breaker of Fig. l, in its open
circuit condition;
; Fig. 3 is a contact travel versus-pressure
characteristics of the circuit breaker of Fig. l;
Fig. 4 is a partial cross-sectional view showing
a modification of gas bleeding means;
~ig. 5 is a partial cross-sectional view showing
another modification of the gas bleeding means,
Fig. 6 is a cross-sectional view taken along
the line VI-VI of Fig. 5;
Fig. 7 is a partial cross sectional view of
another embodiment of the invention, in its closed circuit
condition;
Fig. 8 is a partial cross-sectional view of the
circuit breaker of Fig. 7, in its open circuit condition;
Fig. 9 is a partial cross-sectional view of a
; ~ ~ modification of the embodiment of Fig~ 7;
; Fig. lO is a partial cross-sectional view of
: : .
~ ~ 30 another modification of the embodiment of Fig. 7, in its
~:; ' - ~
: . .
~679~
1 open circuit condition;
Fig. 11 is a partial cross-sectional view of
a still further embodiment of the invention, in its open
circuit condition;
Fig. 12 is a partial cross-sectional view of a
yet further embodiment of the invention in its open
circuit condition;
Fig. 13 is a flow-velocity-versus-pressure
;- characteristics of an arc extinguishing gas flow between
contacts in the circuit breaker of Fig. 12;
Fig. 14 is a partial cross-sectional view of a
further embodiment of the invention, in its open circuit
condition; and
Fig. 15 is a partial cross-sectional view of a
further embodiment of the invention, in its open circuit
condition.
Referring to Fig. 1, there is generally shown
at 1 a puffer type gas-blast cireuit breaker according
to the present invention. The circuit breaker 1 includes
; 20 a vessel 2 filled with an arc extinguishing gas of a
mitary~pressure, and at least one interrupting unit 3
mounted in the vessel 2. The interrupting uni-t ~ includes
a~solid flxed contact 6 which is secured through the
medium of~a tubular insulating member 5 to -the vessel 2,
25~ and a movable contact 7 in alignment with but in opposed
! ~ : , : : '
relatlon~to the fixed c~ontact 6 and movable in the
d1re~otlon;~towards and;away from the fixed contact 6 so
as~to be~engaged with and to be disengaged fro~ the fixed
contact 6,~respectively. The~movable contact 7 includes
30 ~thereln an axial holIow;portion 8 having an opening 9
~ ~ : , ...
7~
1 which opens in that axial free end face of the rnovable
contact 7 which is opposed to the fi~ed contact 6. When
the circuit is in its closed position, the opening 9 is
closed with the fixed contact 6.
: 5 A first cylinder 11 has a substantially closed
end 12 and is integrated with the movable contact 7 in a
manner that the movable contact 7 extends through the
substantially closed end 12 of the first cylinder 11 in
- concentric relation therewith. A first piston assembly
1~ is slidably fitted in a first cylinder 11. ~he first
piston assembly 13 includes: a cylindrical member 14, a
ring-shaped piston member 15 secured to one end of the
cylindrical member 14 and having an outer peripheral
surface which is slidably sealingly fitted in the first
cylinder 11, and an inner peripheral surface defining a
hole 16; and a flange 17 secured to the other end of the ~-
cylindrical member 14. A compression chamber 19 is
defined by a substantially closed end portion 12 of the
first cylinder 11, and ring shaped piston member 15
fitted therein sealingly slidably and inner peripheral
surface of the first cylinder 11, and outer peripheral
surface of a movable contact 7.
A second cylinder 21 is secured through the
medium of a tubular insulating body 23 to a vessel 2.
: 25 One end portion 22 of the second cylinder 21 is provided
~ with a hole 24 positioned in concentric relation thereto,
:~ : with the movable contact 7 being fitted in the hole 24
: ~ sealingly slidably. A second piston 25 is fitted in the :
second:cylinder 21 sealingly slidably, and integrally : :
0 secured to one end.of the movable contact 7 on a side ::
,
~ 7 ~
,
: ~ ~
~0679~L
1 opposite to its free end portion. Thus, a suction chamber
26 is defined by the end 22 of the second cylinder 21,
second piston 25 7 inner peripheral surface of second
- cylinder, and outer peripheral surface of the movable
: 5 contact 7.
~ he flange 17 of the first piston assembly 13
is secured to the surface of end portion 22 of the second
cylinder on a side opposite to the suction chamber 26.
Thus, a chamber 29 is defined by the end portion 22 of the
second cylinder 21, ring-shaped piston member 15, inner
peripheral surface of the cylindrical member 14, and outer
peripheral surface of the movable contact 7. A collector -
30 is provided with a hole 31, while the inner peripheral
surface of the hole 31 is urged against the outer -
15 peripheral surface of the movable contact 7 under the
action o~ springs 32. The collector 30 is formed with a
flange extending in the radial direction inwardly and
engages a flange 35 secured to the end portion 22 of the
:
; ~ ; second cylinder 21~on a~side`opp~osite to the suction
chamber and extending~around a clrcumference of the hole
24 ln the end portion 22. Secured to the substantially
closèd~end portion 12~of the first cylinder 11 on a side
o~pposlte to the;compresslon chamber 18 iB an insulating
cover 36 which encompasses free end portion of the movable
?5 contact 7.~ Disposed on the side opposi-te to the compres-
s~lon chamber wlth respeot~to;the substantl.ally closed
e~d 12~of~the first cyllnder 11 is an annular flange 37
which~is~ integrated with the end 12. An insulating nozzle
38; lS~ secu~ed to~the ~nnular flange 37 in a manner to
30~surro nd~the lnsulating cover 36. An arc-extinguishlng
1~6794~L
1 gas guide passage 39 is defined between the inner
peripheral surface of the insulating nozzle 38 and the
outer peripheral surface of the insulating cover 36, and
is communicated through holes 40 provided in the sub-
stantially closed end 12 of the first cylinder 11 withthe compression chamber 18. ~hus 9 when the movable
contact 7 is disengaged from the fixed contact 6, the
compression chamber 18 is communicated via holes 40~ pas-
sage 39 and opening 9 with the axial hollow portion 8 in
the movable contact 7.
~ he insulating nozzle 38 i.s formed with a throat
portion 42 which is positioned in coaxial relation to the
fixed contact 6. ~he throat portion 42 in the insulating
nozzle 38 is capable of being blocked by the fixed
contact 6. An opening 44 lS provided in an end peripheral
wall of the movable contact 7 on a side opposite to the
free end portion thereof~, so that the axial hollow portion
8 is brought into communication with the suction chamber
26 through the opening 44, when the movable contact 7
is moved in the direction away from the fixed contact 6.
Openings 45 are formed in the peripheral wall
of the second cylinder 21, and the suction chamber 26
may be communicated with a space within the vessel 2,
when that surface of the second piston 21 opposi-te to the . ::
: 25 substantially closed end 22 of the second cylinder 21
overlaps the openings 45. The position of the openings
45 is~such that, as will be described hereinafter, when
t ~ t~ ; the~movable~contact 7 is moved a given distance from the
: fixed oontaot 6, the suc~tion chamber 26 may be communi- :
30: cated with~a space in the vessel 2 through the openings
, ~ ~ : : :
~ 9
~ g67~4~ `~
45-
The piston 25 is connected to a connecting member
48 by means of a pin 47, and the connecting member 48 is
connected to one arm 52 of a '~' shaped link by means of a
5 pin 49, while the '~' shaped link is pivotally supported
by a pin 51. The other arm 53 of the '~' shaped link is
pivotally connected to a driving rod 55 by means of a pin
54, and the driving rod 55 in turn is connected to an -
actuator not shown. One terminal 57 is coupled to the
outer peripheral surface of the second cylinder 21, while
the other terminal 58 is coupled to the fixed contact 6.
Description will now be given of an interrupting
operation of the breaker, hereunder. ~ig. 1 shows an
interrupting unit 3 in a closed circuit condition.
An actuator means not shown is operated to move
the driving rod 55 in an arrow direction 60. According
to the movement o* the driving rod 55, arms 52, 53 of an
'~' shaped link are moved in the direction to keep the
movable contact 7 away from the fixed contact 6 through
20 the medium of a connecting member 48. ~he movement of `
the movable contact 7 in the direction away from the
fixed contact 6 causes the first cylinder 11 integrated
with the movable contact 7 to move in the direction
.
~; towards the first piston 11 as well as causes the second
25 piston 25 integrated wlth the movable contact 7 to move
in the direction away from the substantially closed end
22 of the s~econd cylinder 21. As a result, an arc ~ -
extinguishing gas within the compression chambe~ 18 is
. ~ .
compressed, and the volume of the suction chamber 26 is
30 enlargedj resulting in a large pressure difference between
~ ,
1 0
~6~794L~
1 the compression chamber 18 and the suction chamber 26.
As shown in Fig. 2, when the movable contact 7 is
disengaged from the fixed contact 6, a pressure differ-
ence between the compression chamber 18 and the suction
chamber 26 causes an arc extinguishing gas in the coMpres-
sion chamber 18 to be directed through the hole 40 in
the substantially closed end 12 of the first cylinder 11,
guide passage 39, and opening 9, into the axial hollow
portion 8 and then through the holes 44 provided in the
peripheral wall of the movable contact 7 into the suction
chamber 26. When an arc extinguishing gas flows from the
compression chamber 18 through the passage 39 and opening
9 into the axial hollow portion 8, the arc extinguishing
gas is blown against an arc produced between the movable
contact 7 and the fixed contact 6, so that the arc is
extinguished. When a current to be interrupted reaches
its current zero point, before the fixed contact 6 is
drawn out of the throat portion 42 in the insulating
nozzle 38, an arc is extingu1shed. More particularly,
a difference in pressure between the compression chamber
18 and the suction chamber 26 produces strong arc
extinguishing gas streams, which are blown against an arc
produced between the contacts 6 and 7.
' In case an arc can not be extinguished by a gas
stream directed from the compression chamber 18 to the
suction chamber 26, a gas stream flowing through the
throat portion 42 in the insulating nozzle extinguishes
. . .
an arc in cooperation with the firstly referred gas
stream. A volume of the suction chamber 26 is so selected
that a gas stream be delivered from the compréssion
~ii794~L
1 chamber 18 to the suction chamber 26, until the fixed
contact 6 is drawn out of the throat portion 42 in the .
insulating nozzle 38, although the volume of the suction
chamber 26 varies depending on a current capacity.
In case the suction chamber 26 is so designed
as to be isolated from an ambient gas contained in a
space in the vessel 2 until its reaching an open position,
even after the fixed contact 6 has been drawn out of the
throat portion 42 in the insulating nozzle 38, then gas
10 heated by an arc produced between the contacts 6, 7 is
introduced from the compression chamber into the suction
chamber 26, so that a pressure in the suction chamber is
built up to a level higher than that of the ambient gas
in the vessel 2, thus resulting in a reduced difference
in pressure between the compresslon chamber 18 and the
suction chamber 26, thereby failing to provlde a gas
stream to be blown against an arc, which stream runs from :
the compression chamber through the axial hollow portion .
8 in the contact 7 into the suction chamber 26. To avoid
this, there is provided a gas bleeding means for bleeding :
the gas from the suction chamber into the ambient gas
space, soon after or when the fixed contact 6 has been
: ~ : drawn out of the throat portion in the insulating nozzle
: ; : 38. In the embodiments shown in Figs. 1 and 2, the
aforesaid gas bleeding means is provided in the form of
. ,:
: openings provided in:the peripheral W211 of the second
cylinder 21. In other words7 soon after or when the
: fixed contact 6 has been drawn out of the throat portion
42:in the insulating nozzle ~8, the second piston 25
reaches the openlng 45. As a result, the suction chamber
~ ~ :
; - 12 - .
~6794~
1 26 is communicated or open through the openings 45 with
or to ambient gas space, so that a pressure in the suction
chamber 26 is no longer built up or maintained at the same
level to that of ambient gas.
When the fixed contact 6 is drawn out of the
throat portion 42 in the insulating nozzle 26, then an
arc extinguishing gas compressed in the compression
chamber 18 is discharged through the throat portion 42
into the vessel 2, and thus there are produced gas streams
directed towards the fixed contact 6 as well as towards
the movable contact 7 in the directions opposite to each
other, so that an arc produced between the both contacts
can be extinguished certainly.
Fig. 3 is a diagram showing the relationship
among a travel (~) of the movable contact, a pressure
(Pl) in the compression chamber 18, and a pressure (P2)
in the suction chamber 28, upon the current interruptlon
of a puffer type gas-blast circuit breaker according to
the present lnvention.
As can be seen from Fig. 3, since an arc
extinguishing gas heated by the arc, which has been
introduced into the suction chamber, soon after or ~Ihen
the fixed contact 6 is drawn out of the throat portion 42
in the insulating nozzle 38, in the terminating stage of
an opening operation of contacts, is bled through the
openings 45 into a space in the vessel 2, a pressure (P2)
:
in the suction chamber 28 may be maintained lower than a
pressure (Po) in the vessel 2, thereby maintaining a large
pressure difference between the compression chamber 18
- : : : :: .
and the suction ohamber 26. Fig. 4 shows a modification
- 13 -
.
~ti79fl~
1 of the aforesaid gas bleeding means, with the similar
parts designated same reference numerals in common with
those given in Fig. 1. Referring to Fig. 4, a flange of
a second cylinder 21a is coupled through the medium of a
cylindrical member 71 to a tubular insulating body 2~.
A space 72 defined by the inner peripheral surface 71 is
communicated through an opening provided in the peripheral
wall of the cylindrical member 71 with a space in the
vessel 2. ~he space 72 is continuous with a suction
chamber 26 along a joint of the second cylinder 21a to the
cylindrical member 71, and has a diameter larger than the
diameter of the suction chamber 26. A joint 75 between
the suction chamber 26 having a small diameter and the
space 72 having a large diameter and positioned in opposed
relation thereto are so located that the second piston 25
may reach the joint 75 soon after or when the fixed
contact 6 is drawn out of the throat portion 42 in the
insulating nozzle 38. In this manner, the suction chambe-r
26 is brought into communication with the space 72, soon
20 after or when the fixed contact 6 is drawn out of the ~
throat portion in the insulating nozzle ~8, so that gas is ~;
bled from the suction chamber 26 by way of the opening 7
into a space in the vessel 2.
~igs. 5 and 6 show another modification of the
gas bleeding means, with the similar parts designa-ted
sarne reference numerals in common with those given in
~ig~ 1. Referring to ~igs. 5 and 6, elongated members 81
are secured to or integrally coupled to the inner
perlpheral sur-face of the aecond cylinder 21 a-t an equal
spacing in the circumferential direction around the axis
~C~6794:1
1 of the second cylinder. Cut-away portion 82, whose
shapes are complementary to the aforesaid elongated
members, are defined in the peripheral surface of the
second cylinder 25. Thus, the elongated members 81 are
slidably sealingly fitted in the cut-away portions 82.
In a closed circuit condition, the cut-away portions 82
are blocked with elongated members 81. Upon a circuit-
opening operation, the elongated members 81 are drawn
out of cut-away portions 82, soon after or simultaneously
when the fixed contact is drawn out of the throat portion
; in the insulating nozzle, with the result that the suctlon
chamber 26 is open to or communicated with a space in the
vessel. For certain bringing the elongated members 81
into engagement with the cut-away portions 82 in the
second piston 25, in a closed circuit condition, guide
portions 83 are provided in the inner surface of the
second cylinder 21. ~he guide members 83 are fitted in
the cut-away portions 82 in the second piston for guiding
the movement thereof. Apparently, it is preferable that
an initial volume of a space in the suction chamber and
: .
a volume associated herewith be minimized, thereby
enhancing~a vacuum effect in the suction chamber at the
initial stage of a circuit opening operation to increase
a pressure difference between the compression chamber and
the suction ohamber. For the purpose of this, after a
;; - circuit openlng operatlon, it is preferable that a volume,
or a dead volume, in the axial hollow portion in the
movable contact,~whloh is com~unicated with the suction
chamber, be minimized. S-tated differently, it is
preferable that the suction chamber be positioned close
~:~ 15
: ~:
~LC3679~
1 to the compression chamber. Figs. 7 and 8 show another
embodiment of the invention, in which a collector 30
shown in Fig. 1 is eliminated to bring the suction chamber
closer to the compression chamber, thereby minimizing a
volume in the axial hollow portion in the movable contact.
In these figures, the similar parts are designated same
reference numerals in common with those given in Fig. 1.
Referring to Figs. 7 and 8, a second cylinder
121 having a substantially closed end portion 122 is
secured through the medium of an insulating body 23 to a
vessel as in the manner sho~n in Fig. 1. The substantial-
, ly closed end portion 122 of the second cylinder 121 is
sealingly slidably fitted in a first cylinder 11, so that
- the substantially closed end portion 122 may define a
15 first pis-ton 115. The first piston 115 is provided with
,~ a hole 116 positioned in concentric relation thereto,
'~ , with a movable contact 7 fitted in the hole 116 sealingly
, slidingly. Thus, a compression chamber 18 is defined by
the substantially closed end portion 122, first piston
" 20 115, inner peripheral surface of the first cylinder 115,
and outer peripheral surface of the movable contact 7.
In the embodiment,shown in Figs. 7 and 8, a
cylindrical collector 130 is used in place of the
collector 30 of Fig. 1. The collector 130 includes a
cylindrical member 131 and two or more contacting pieces
132 extending from one axial end of the cylindrical
member 131 towards the fixed contact 6. The two or more
contacting pieces 132 are positioned at an equal spacing
in the circumferential direction of the cylindrical member
30 131. A free end o~f each contacting piec,e 132 is urged ~ '
- 16 ~
.~.; , . . . -
:. , , :. -. . . . .
~(~679~L~
1 against the outer peripheral surface of the first cylinder
11 under the action of a spring 133. ~he collector 1~0
has a flange at the other end, and which flange is press-
fitted around the flange of -the second cylinder 121.
A terminal 57 is secured to the outer peripheral surface
of the cylindrical member 1~1 of the collector 1~0.
~ he provision of the collector 130 in place of
the collector 30 of Fig. 1 permits to make smaller a space
in the axial hollow portion 8 in the movable contact 7.
In this case, however, case should be taken to the posi-
tion of opening 45 serving as gas bleeding means. In
other words, if the suction chamber is brought closer to
the compressure chamber 18, and a communicating hole 45
is provided in the peripheral wall of the second cylinder
121 for bleeding gas from the suction chamber into a
vessel, soon after or simultaneously when the fixed
contact 6 is drawn out of the throat portion 42 in the
insulating nozzle 38, then there arises a possibility of
the communicating hole 45 overlapping the first cylinder
11, in the case of a circuit breaker wherein a distance
.
between contacts is considerably long. In such a case,
gas acting~on an arc in the suction chamber directly
impinges on the inner surface of the first cylinder 11,
thereby d~naging the aforesaid inner surface. ~he inner
surface of the first cylinder 11 should provide a smooth
; ~ sliding s~rface for the first piston 115, and hence a
-~ damage on -the aforesaid inner surface should be prevented.
~ .
Wlth the embodiment shown in Flgs. 7 and 8,
the openings 45 is provided in the peripheral wall of the
8eaond oylinder 121 as far from the closed end 122 of the
- 17 - ,
~i794~
1 second cylinder 121 as possible. ~he second piston 125
is fitted in the second cylinder 121 sealingly slidingly.
The second piston 125 is integrally secured to the movable
contact 7 on a side opposite to the free end portion of
the contact 7. As shown in Fig. 8, the second piston 125
- is formed with a stepped portion 191 on a side opposed to
the subs~antially closed end portion 122 of the second
cylinder 121, while the inner surface of the substantially
closed end of the second cylinder 121 on a side opposed
to the second piston 125 is formed with a stepped portion
192 which faces the stepped portion of the second piston.
~he stepped portions 191 and 192 define a suction chamber
126 extending in the direction of the movable contact 7
moving away from the fixed contact.
~hus, according to the provision of the suction
chamber 126 which may extend or may be enlarged in the
direction away from the fixed contact 6, the openings 45
for bleeding gas from the suction chamber into the vessel
therethrough can be positioned apart from the substantlally
closed end portion 122 of the second cylinder 21j soon
- ~ after or simultaneously when the fixed contact 6 is
~ drawn~out of the throat portion 42 in the insulating nozzle
:
38. Accordingly, gas being bled from the suction chamber
` ~ 126~through the opening 45 into a space in the vessel
~;~ 25 ma be prevented from impinging on the i~ner surface of ~ -
the~first cylinder 11. ~ ~ -
Figs. 9 is a modification of the embodiment of
Fig. 7, with the similar parts designated same reference
numerals in common with~those given in Fig. 1. As shown
; ~ 30 ~in Flg. 9, a back slde of a first piston 115a is formed
.. : . . . ~ . . . .. . . . . . . . . .. i , . . . ..
~ILCI 6~79~
1 with a convex surface 192a which is divergent in the
direction to open a path. A second piston 125a i~ pro-
vided with a convex surface l91a complementary to the
concave surface 192a. As a result, there is provided a
suction chamber 126a having curved surfaces ex-tending
along the flow of gas between the openings 44 provided in
the peripheral wall of the movable contact 7 and
openings 45 provided in the peripheral wall of the second
cylinder 121a. When the suction chamber 126a is communi-
cated with a space in the contact 7 through the aboveopenings, then gas may be smoothly discharged from the
- suction chamber 126a through the axial hollow portion 8
provided in the contact 7 into a space in the vessel.
Fig. 10 shows another modification of the
embodiment of Fig. 7, with the similar parts designated
same reference numerals in common with those given in
Fig. 7.
As shown in Fig. 10, the back sur-face of a
first piston 115 and the surface of a second piston in
opposed relation thereto are flat, while slits 196 are
provided in the outer periphery of the second piston
125b. The slits 196 extend in the direction to open a
: -
path and adapted to be closed with the inner peripheral
surface of the seoond cylinder 121b at the initial stage,
and to face a communicating holes 45. ~n this case, an
empty volume of the slits 196 will be a dead volume for
a suction chamber 126b. In case such a dead space can
not be neglected, then as shown in Fig. 8 projecting
~:
portions may be provided on the back surface of the second
piston so as to fit in the slits 196.
19
~6794: L
1 Fig. 11 shows still another embodiment of the
present invention3 wherein a first piston is movable and
a first cylinder is fixed. In this case, as well, the
similar parts are designated same reference numerals
in common with those of ~ig. 1. As in Fig. 1, a second
cylinder 22 is secured to a vessel through the medium of a
cvvlindrical insulating member. A first cylinder 21 is
continuous through the medium of a common, substantially
closed end 222, with a second cylinder 221 in opposed
relation. ~he common, substantially closed end 223 has
an opening 224 in its center, while a movable contact 7
is slidably sealingly fitted in the opening 224. A first
piston 215 which is slidably fitted in the first cylinder
211 is integrally connected to a movable contact 7 which
extends through the center of the piston 215. A com-
pression chamber 218 is defined by the inner perlpheral
surface of the first cylinder 211, the common, substantial-
ly closed end 222, first piston 215, and the outer
;~ pe~ipheral surface of the movable contact 7.
~he first piston 215 is formed with an annular -
flange~237 on the side opposite to the compression
chamber 218, while an insulating nozzle 381 is secured
to the annular flange 237 in a manner to surround the
free~ end portion of the movable contact 7, as in Fig. 1.
25; A second piston 225 is integrally connected to
~ - :
the movable contact 7 at an end opposite to the free end
thereof and slldably fitted in a second cylinder 221.
Thus, a suction chamber 226 is defined by the comrnon,
substantially~closed~end~222, the inner peripheral surface
30~ of the~ seoond oyllnder 221, the second piston 225, and
, ~
- 20 _
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1~679~
1 the outer peripheral surface of the movable contact 7.
As described above, the first cylinder defining
the compression chamber should not necessarily be con-
nected to the movable contact. It is to be understood
that a suction chamber can be defined as that the second
cylinder is connected to the movable contact and the
second piston is fixed, although in Figs. 1 and 2 the
~ second cylinder defining the suction chamber is secured to
;~ a vessel.
~ig. 12 shows still another embodiment of the
- invention, in which an axial hollow portion is provided
in a fixed contact, with the similar parts designated
same reference numerals in common with those given in
- Fig. 1.
As shown in Fig. 2, a fixed contact 306 is
provided with an axial hollow portion 361 running there-
~ through. ~he axial hollow portion ~61 has an open end ~-
-` ~ 362 and~a closed end 363,~while an opening 364 is provided
in a peripheral wall of the flxed contact 361 adjacent to
- ~ 20 the closed end 363j in a manner that the axial hollow
portlon 361 is oommunicated through the openings ~64 with
a space~1n the vessel. ~he axial hollow portlon 361 has
a~throat portion 365 adjacent to the open end 362 thereof.
A movable contact 307 is provided with an
;Z5 axial hollow portion 308~running therethrough. ~he ax1al
hollow~portlon~308 has an ~open end 309 close to the fixed
oontact 306, and a closed end 310~awav from the fixed
oontact 306.~ Openlngs~344 are~provided in the peripheral
wall~of the movable contact 307 adjacent to the cloæed
30~ end~310. The axial hollow portion ~oa is oommunicated
21 -
~L~6794~
1 through the openings 344 with the suction chamber 26.
The axial hollow portion 308 is formed with a throat
portion 367 adjacent to its open end. The throat portion
367 of the axial hollow portion 308 in the movable
5 contact 307 has a diameter smaller than that of the throat
portion 356 of the axial hollow portion 361 in the fixed
contact 306.
In operation, when the movable contact 308 moves
in the direction away from the fixed contact 306 9 then
an extinguishing gas in the compression chamber is
compressed, while a volume of the suction chamber 26 is
enlarged. A pressure difference betwe~ the compression
chamber 18 and the suction chamber 26 causes an arc
extinguishing gas to be directed from the compression
15 chamber 18 via openings 40, guide passage 39 and axial
hollow portion 308, into the suction chamber 26. On the ;~
other hand, an increase in volume of the suction chamber
26 causes an arc extinguishine gas to be introduced from
the vessel, via openings 364 provided in the peripheral
20 wall of the fixed contact 306 and axial hollow portion
361, into the suction chamber 26. A gas stream flowing
from the compression chamber 18 via guide passage 39 into
the axial hollow portion 308 in the movable contact 307, -~
and a gas stream flowing from a space in the vessel via
25 openings 364 and axlal hollow portion 361 in the fixed
contact 306 blow off an arc produced between the contacts
-
; ~ 306 and 307.
Fig. 12 shows gas steams produced in the
initial phase of an~opening operation of the contacts.
As shown in Fig. 3, an initial pressure build-up
- 2~ -
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~06794~
1 in the compression chamber 18 is slow. On the other hand,
a sharp pressure drop -takes place in the suction chamber
26. For this reason, in the initial phase of an opening
operation of the both contacts, there are formed a gas
stream A directed from the compression chamber 18 towards
the suction chamber 26, and another gas stream B directed
from the hollow portion in the hollow fixed contact 1
towards the suction chamber 26. These gas streams flow
through the axial hollow portion 308 in the movable
contact 307. More particularly, gas streams A and B join
together at the tip of the movable contact, which is
opposed to the fixed contact, and then flow into the
suction chamber 26.
~ig. 13 is an enlarged view of the neighbor-
hood of the contacts 306) 307~ showing a pressure
distribution P of gas in the initial phase of an opening
operation of the contacts and a flow velocity distribu-
tion v. ~ig. 13 refers to an initial phase of an opening
operation of the contacts. In this figure, a gas stream
20 A from the compression chamber affords little pressure ~ -
rise, and hence is purgea therefrom merely according to
: .
the compression of a compression chamber. Accordingly,
a pressure of gas stream ~ becomes almost the sarne level
as that of the gas stream B. The pressure distribution P
,
and flow velocity distribution v are those taken along the
axis of the contacts.
~ ~ , . . .
Re~erring to the flow velocity distribution v,
t~he diameter of the throat portion 367 on a side of the
;movable contact 307, which is opposed to the fixed r~ ... ..
30 ~contact, is reduced, and the~flow velocity is maximized
23 _
: .
~067941
1 in the throat portion 367. This fact that the flow
veloclty peaks at the throat portion 367 is advantageous
in shortening an arcing time according to the effect of
the suction chamber 26, during the time until the fixed
contact 306 is drawn out of the insulating nozzle 38.
As best shown in the pressure distributlon P, the diameter
of the throat portion 365 of the fixed contact 306 is
larger than the diameter of the throat portion 367 of the
movable contact 307, so that a pressure of gas stream
in a clearance between the contacts remains almost
unchanged when joining the gas stream A. As a result, a
pressure of an arc extinguishing gas is built up between
the fixed contact and the movable contact, with an
accompanying increase in density of an arc extinguishing
gas being blown against an arc, so that an arc extinguish-
- ing effect is enhanced. In addition, in case a pressure
-~ of gas between the contacts is built up, an insulation
resistance-voltage-withstanding characteristic between
.,
contacts is enhanced, thereby lnsuring positive current
interruption in a region, wherein a distance between the
~contacts is short.
~ ig. 14 is stlll another embodiment of the
invention, in which a suction chamber cooperates with a
flxed contact, with the similar par-ts designated same
reference numerals in common with those given in ~ig. 1.
A fixed contact 406 is secured through the
medlum of a fixing disc 471 ana tubular insulating body
405 to a vessel 2. The~ ~ixed contact 406 has an axial
hollow portlon~461 runnlng therethrough~ The axial
30 ~hollow portion 461 has an open end 462 on a side close to
, ...
~ 24 -
: - . . . .; . . .. . , . .. . ~ , . . .. . .. .
1~367~4~
1 the movable contact 407, and a closed end 463 away from
the movable contact 407. A third cylinder 472 has a
closed end 473, while a fixed contact 406 is secured to
the third cylinder 472 in a manner that the fixed contact
406 pierces through the closed end portion 473 in con-
centric relation thereto. The third cylinder 472 is
coupled to a terminal on an outer periphery of the
cylinder 472.
A second piston 425 is slidably fitted ln the
third cylinder 472. ~he second piston 425 is provided
with a hole 474 in its center, while the fixed contact
406 is fitted in the hole 474 sealingly. Thus, the
suction chamber 426 is defined by the closed end 473 of
the third cylinder 472, second piston 425, inner peripheral
surface of the third cylinder, and outer peripheral
surface of the fixed contact 406. Openings 475 are
provided in the peripheral wall of the fixed contact 406
with the axial hollow portion 461 in the fixed contact
406 and suction chamber 426 being communicated with each
other.
Connectlng members 476 are integrally secured
to the second piston 425 at an equal spacing around the
:~ :
second Piston on a side opposite to the suction chamber !.~.,.. ''
426. The connecting members 476 extend through holes 477
25~ provlded~in the flxed disc 471 and terminate at the disc~
78. The disc 478 is secured through the medium of a pin
480 to an arm 479~of a '~' shaped link, while the other
arm 481~is plvoted~t~o a drlving rod 482. The driving rod
482 is coupled to an actuator not shown. The actuator
0 is operated in synchronism with another actuator which is
: , :
~ 25 -
~ ~ .
1~167~41
1 not shown but drives the movable contact 407. Alterna-
tively, the movable contact 407 and second piston 425 may
be driven by a single common actuator.
In operation, when the movable contact 407 is
moved in the direction away from the fixed contact 406,
then an arc extinguishing gas is compressed in the com-
pression chamber 18, and a volume of the suction chamber
426 is enlarged. A difference in pressure between the
compression chamber 18 and the suction chamber 426 causes
an arc extinguishing gas to be directed from the compres-
- sion chamber 18 through the openings 40 provided in the
substantially closed end portion 12 of the first cylinder
11, and the guide passage 39 into the axial hollow
portion 461 in the fixed contact 406, and then through
` 15 the opening 475 into the suction chamber 426. When a
volume of the suction chamber 426 is enlarged, then an
arc extinguishing gas in a spaoe in the vessel 2 flows
through the opening 45 provided in the peripheral wall of
the second cylinder 21 and opening 44 provided in the
~; 20 perlpheral wall of the movable contact 407 mto the axial ~-
hollow portion 408 in the movable contact 407, and then
through the axial hollow portion 461 in the fixed contact
; 406 into~the suctlon chamber 426.
Cut-away portion 483 provided in the peripheral
25~wall of the third cylinder is so positioned that the
;: ~ : . ,
suction chamber 426 may be communicated through the cut-
aWay~p;ortion 483 wlth a space in the vessel, soon after
or simultaneously when the flxed contact 406 lS drawn out
of the throat portion~42~of` the insulating nozzle 38.
30 ~ ~As m the~case of; Flg. 12, the axlal hollow
26 - ~ ~
~067~4~
1 portion 461 in the fixed contact 406 is formed with a
throat portion 465 in the close vicinity of its open end
462, while the axial hollow portion ~08 in the movable
contact ~07 is formed with a throat portion in the close
vicinity of its open end 40g. In -this respect, it is
preferable that the diameter of the throat portion 465
of the fixed contact be smaller than that of the tl1roat
portion 467 of the movable contact, thereby preventing a
- pressure drop.
~ig. 15 shows s-till an other embodiment of the
invention, in which the fixed contact and movable contact
cooperate with the suction chamber, with the similar
parts designated same reference numerals in common with
those given in ~ig. 1.
In ~ig. 15, a ~ixed contact 506 which is
secured through the medium of a tubular insulating member
505 and fixing disc 571 to a vessel 2. ~he ~ixed contact
, .... .. .
506 includes an axial hollow portion 561 therein. ~he
axial hollow portions 561 has an opening 562 on the side
of the movable contact 507, and a closed end 56~ on the
side away ~rom the movable contact 507. ~ third cylinder
572 haa a closed end 573 thereof, and the fixed contact -
506 is integrally secured to the third cylinder 572 in a
manner that -the fixed contact 506 extends through the
closed end 573 of the cylinder 572 in concentric relation
therewith. The third cylinder 572 has connected thereto
~: ,
a terminal 558.
A third piston 525 is slidably fltted in the
third cylinder 572. ~ The third piston 525 has an opening - ;
- ,
~ 0 574 in its center, with the fixed contact 506 slidably
,~ ~ ~ ,. . .,:
27 _
'
~,: : .' '
~79~
1 sealingly fitted in the eentral opening 574. A second
suetion chamber 526 is defined by the inner peripheral
surfaee of the third eylinde:r 572, the outer peripheral
surfaee of the fixed contaet 506, a closed end 573 o-f the
5 third cylinder, and third piston 525. Openings 575 are
provided in the peripheral wall of the fixed contaet 506,
so that the axial hollow por-tion 561 in the fixed contact
506 may be communicated with the second suction chamber
526.
Integrally secured to the third piston 525 on
the side opposite to the second suction chamber 526 are
eonneeting members 576, only three of whieh are shown,
and are arranged at an equal angular spaeing around the
fixed contact 506. The connecting members 576 extend
15 through apertures 577 provided in the fixing dise 571,
terminate at the dise 578, and are seeured to the dise
578. The dise 578 is pivotally eonneeted to one arm 579
of a '~' shaped link by means of a pin 580. The other
arm 581 of the '~' shaped link is pivotally eonneeted to
20 a driving rod 582. The driving rod 582 is eoupled to an
~ aetuator not shown. This actuator may be operated m
; synchronism with an aetuator (not shown) for driving
the second piston 25. Alternatively, the seeond and third
piston 25, 525 may be driven by a single common actuator.
In operation, when the movable eontact 7 is
moved away from the~flxed eentaet 506, an are extinguish-
;ing gas in the eompression ehamber 18 is eompressed,
.
; whereupon -the volumes of`the first and seeond suetion
: ehambers 26 and 526 are enlarged. An are extinguishing
- 30 gas in the~eompression ehamber 18 is direeted, on one
- 28
... .... ... ,, .. ,. ,. ... ,., .- . . . . .. .... . . ~ - . ~ . . . . .. .
. . . .. .. . .. . ...... . .. . . . . . .. ... ..
1C)67941
1 hand, via holes 40 provided in the substantially closed
end 12 of -the first cyl~nder 11, guide passage 39, axial
hollow portion 508, and openings 44 in the movable
contact 507, into the first suction chamber 26 and then
5 through openings 45 provided in the peripheral wall of the
second cylinder 21 into the space in the vessel 2. The
arc extinguishing gas, on the other hand, is directed
via the holes 40 in the substantially closed end 12 in
the first cylinder 11, guide passage 39, axial hollow
portion 561 in the fixed contact 506, and openings 575
-~ into the second suction chamber 526 and via cut-away
portions 583 provided in the peripheral wall of the third
cylinder 572 into the space in the vessel 2. I-t is
needless to mention that the openings 45 provided in the
15 peripheral wall of the second cylinder 11, and cut-away
: . por-tions 583 provided in the peripheral wall of the third
cylinder 572 are so positioned that the suction chambers
26 and 526 may be communicated with or opened to a space
in the vessel through the openings 45 and cut-away
20 portions 583, respectively, soon after or simultaneously
: when the fixed contact 506 is draw out of the throat
portion 42 in the insulating nozzle 38.
~ As~has been described earlier, the auction
.~ chamber may be opened, simultaneously when one of the ::
contacts is drawn out of a throat portion in an insulating
nozzle, so that the suction effect of the suction chamber
at the inltial stage may be thorougl1ly utilized, and the
: flow of a gas stream is not hindered. Unlike a suction
~::
chamber of the type which is not opened in this manner, a
:~ 30 :gas strearn which is produced due to a pressure difference ~.
.
- 29
:; ~ ' .
~C36799~
1 between a compression chamber and an ambient gas ma~ be
maintained after the suction chamber has been opened.
In this manner, pressure build-up in a suction chamber
is suppressed, thereby improving an interrupting
performance of a breaker.
~:
::
: : :
: .:
- -.
:. .
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: ,
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3 0
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