Note: Descriptions are shown in the official language in which they were submitted.
Wo 95/2023~ P~ ' 7`''
0 218172~'
-- 1 --
~n~ ly"
The invention relates to a blade assembly, particularly
for use in circuit breakers.
Circuit breakers generally include a breaker mechanism
5 mounted in a housing. Such breaker -hAni ! generally
comprise a large number of separate pieces which are
assembled in the ho-~sing. ~3ecause of the number of
pieces involved and the complexity of such ~h~ni ~mc it
is extremely difficult to automate the assembly
10 operation.
According to the invention there is provided a blade
assembly for a switch such ag a circuit breaker, the
blade assembly including a blade member, a trip lever
and a contact holder, the blade member being of
15 insulating material, and having a trip lever mounting
means and a contact holder mounting means.
In a preferred: '7~ t of the invention the blade
member includes a pab~l mounting means. Preferably the
blade member includes an integral indicator flag.
2 0 In one : i t of the invention the blade member
comprises a pair of opposed side walls and connecting
wall means extending between the side walls. Preferably
the connecting wall means comprises a connecting web
ad~acent a contact end of the blade member and an end
25 connecting wall adjacent an opposite end. Typically the
end connecting wall includes an extension defining an
integral indicator flag.
Preferably the trip lever mounting means comprises means
for snap fittingly engaging with the trip lever.
30 Typically the trip lever mounting means comprises an
integral pivot pin and the trip lever includes a recess
LuLL~ ul~ding to the integral pivot pin for snap fitting
engagement .
~17~8
-- 2 --
Preferably the trip lever includes a no6e portion for
engaging with a corresponding recess in the pawl.
Advantageously the trip lever includes a spring means to
urge the nose portion of the trip lever into engagement
5 with the pawl. Preferably the integral spring means
comprises a flexible arm which extends from the trip
lever to engage with the blade member. Ideally the
flexible arm is integral with the trip lever.
In a preferred ~rrAn,3 - t the trip lever is of
lO insulating material.
In one embodiment of the invention the contact holder is
of electrically conductive material and the contact
holder mounting means and contact holder have
interengaging formations for an~:lqi nr the contact holder
15 with the blade member. Preferably the contact mounting
means includes opposed recesses in side walls of the
blade member adjacent a contact end of the blade member.
Typically the assembly includes ramp means for guiding
the contact holder into the recesses on fitting.
20 In a preferred embodiment of the invention the pawl
mounting means comprises opposed pivot holes in the
blade member to receive a pawl mounting pivot pin, the
p~lwl being mounted to the pivot pin.
The invention also provides a switch incuL~oLtlting a
25 blade assembly according to the invention.
The invention further provides a circuit breaker
incorporating a blade assembly according to the
invention .
The invention will be more clearly understood from the
30 following description thereof, given by way of example
only with reference to the ~rcl ~nying drawings in
which: -
~ig. l is an exploded perspective view of a bladeassembly according to the invention;
2181728
~1-- W0 9~l2023s r.~
Fig. 2 i5 an elevational view of the assembly;
Fig. 3 is a cross sectional view of the assembly;
Fig. 4 is a plan view of a circuit breaker
incorporating the assembly in an on position of use
with the contacts closed;
Fig. 5 is a plan view of the circuit breaker of Fig.
4 in a tripped po~ition ~ith a handle held in the on
position; and
Fig. 6 is a plan view of the circuit breaker of Fig.
4 in an off position with a handle switched off.
Referriny to the dra~ings and initially to Figs. 1 to 3
thereof there is illlustrated a blade assembly according
to the invention and indicated by the reference numeral
The blade assembly 1 comprises a blade member 2A, a trip
lever 2B, a contact ]lolder 2C and, in this case, also a
pawl 2D. At least the blade member 2A, and preferably
also the trip lever 2B and the pawl 2D are of
20 insulating, typically plastics material and are
typically injection moulded.
The blade member 2A has a rear contact end 5 and a front
flag end 6 and comprises a pair of opposed side walls 3,
4 which are joined by a flag end connecting wall 8, an
25 incr iate wall 10 and a connecting web 11 ad~acent
the contact end 5. The flag end connecting wall 8 has
an extension 12 which defines, in use, an indicator flag
as will be described in more detail below. The
extension 12 may extend upwardly as illustrated or
3 0 downwardly .
Opposed holes 13 are erovided in each side wall 3, 4
ad~acent the flag end 6 to receive a pawl mounting pivot
pin 14 which passes through a first pivot hole 15 in the
pawl 2D for pivotally mounting the pawl 2D to the blade
35 member. The pawl 2D in this case also includes a second
W0 95/20235 2 1 8 1 7 2 8 . ./1 - ~
pivot hole 19 for receiving a link as will be described
below .
A trip lever mounting pivot pin 20 is integrally moulded
with the blade member ~2A and extends between and
pro~ects from the blade side walls 3, 4 to define stub
projections 20a. The pin 20 is sized to snap-fittingly
engage with a coLl~DL,ulldingly shaped recess 21 in the
trip lever 2B. The trip lever 2B has a rear leg 26 and
a forward leg 23 with a front nose portion 24 which
engages with a oLLvD~vl-ding recess 25 in the pawl 2D as
will be particularly apparent from Fig. 3. An integral
flexible arm 27 extends rearwardly from the trip lever
2B to engage llnrl~rnl~ath the web 11 of the blade member
2A. The arm 27 acts as a biassing spring to urge the
nose 24 of the trip lever 2B into ~,, t with the
recess 25 in the pawl 2D.
The contact holder 2C is of electrically conductive
material and snap-fittingly engages with the blade
member 2A at the contact end 5. A moving contact 34
(Figs. 4 to 6) is fitted to the contact holder 2C, for
example by riveting, welding or forming in situ. The
contact holder 2C is of generally L-shape having an
upright portion 32 and a horizontal portion 31 which are
cut-away on both sides at 33 to engage with the blade
member 2A. At the contact end 5, the blade side walls
3, 4 each have an inwardly extending ramp formation 35
and an inwardly extending stop rib 36 which are spaced-
apart to define thel~beL~ recesses 37 for engaging
with the contact holder 2C. On assembly, the upright
portion 32 of the contact holder 2C is pressed forwardly
to ride over the ramp formations 35 and snap into the
recesses 37.
Referring to Figs. 4 to 6 the blade assembly 1 described
above is shown mounted in one particular circuit breaker
50. The circuit breaker 50 has a housing 56 and
includes a line t~rminAl 51 for coupling to a source of
electricity and a load terminal 52 for coupling to a
load. A braided pigtail 53 is connected for example by
crimping, welding or fixing, between the line tPrm;nAl
~ W0 95~2023S 21817 2 8 r~ 5 ~ -
_ 5 _
51 and the contact holder 2C of the blade assembly 1.
The stub pro~ectionls 20a of the trip lever mounting
pivot pin 20 of the assembly 1 engage with .:ulL~ or.ding
pivot recesses (not shown) in the housing 56. In a
5 normal contacts closed position illustrated in Fig. 4
the moving contact 3 4 carried by the contact holder 2C
is engaged with a f i~l:ed contact 5 8 .
The current path from the fixed contact 58 includes a
coil 60 and a load conductor 61 to which the load
~rminAl 52 is connected. The circuit breaker in this
case also includes am arc runner 63 and an arc stack 64
which cooperate to break any arc formed when the circuit
breaker opens and the contacts 34, 58 are separated
under load. The contacts 34, 58 may be separated in
Lt~onse to operation of a bimetal (not shown) or by a
rod 65 which is normally biased downwardly by a solenoid
spring 62. The rod 65 is disposed within the coil 60
and is engagable against the rear leg 26 of the trip
lever 2B of the blade assembly 1.
A cam 68 has an operating handle 69. A link 70 connects
the cam 68 and pawl 2D through the hole 1~ in the pawl
2D .
The housing 56 inc] udes a viewing window 71 through
which the flag 12 of the blade member 2A may be viewed
when the contacts 34, 58 are in the off and tripped
positions illustrated in Figs. 5 and 6. In the tripped
or of f positions a spring 55 urges the blade assembly
about the pivot defined by the stub projections 20a so
that the moving contact 34 carried by the contact holder
2C is disengaged from the fixed contact 58.
In use, the circuil_ breaker is tripped either by a
thermal overload as detected by a bimetal (not shown) or
by a current surge actuator defined by the coil 60. In
the normal closed position the rod 65 is downwardly
biased by the solenoid spring 62 and current passing
through the coil 6a sets up an electromagnetic field
acting on the rod 65. When the eleuLL, ~gn~tic force
set up in the coil 60 is disturbed by a current surge
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .. ... .. .. . .
Woss/20235 r~"ll c~ c
2l81728
-- 6 --
the rod 65 moves up to engaqe the rear leg 26 of the
trip lever 2B of the blade assembly. This action pushes
the forward leg 23 of the trip lever 2B downwardly so
that the nose 24 of the trip lever 2B disengages from
5 the recess in the pawl 2D. The spring 55 causes the
contacts 34, 58 to separate.
Referring to Fig. 6, when the handle 69 is moved to the
off position ,v L of the link 70 causes the pawl 2D
to move about from the nose 24 of the trip lever 2B.
10 The spring 55 urges the blade assembly 1 about the pivot
defined by the stub projections 20a and the moving
contact 34 is disengaged from the fixed contact 58.
It will be appreciated that the blade assembly of the
invention is of low mass and is without expensive
15 conducting materials such as copper ~,, Ls. There
are substantially less parts than in conventional blade
assemblies so that material and assembly costs are
substantially reduced. Thus, a much more economical and
efficient method of manufacture may be achieved.
20 It will also be appreciated that the spring 55 may be of
any suitable type such as a helical, coil or leaf
spring .
It will further be appreciated that while the invention
has been de8cribed with particular reference to one type
25 of circuit breaker it has wide applications not only to
many dif ferent types of circuit breaker but also to
switches in general.
The invention is not limited to the embodiments
hereinbefore described, but may be varied in
30 construction and detail.
