Note: Descriptions are shown in the official language in which they were submitted.
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ACTUATOR FOR AUXILIARY SWITCH AND
CIRCUIT BREAKER INCORPORATING THE SAME
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Patent
Application Serial No. 60/615,446, filed October 1, 2004.
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to circuit breakers with auxiliary switches that
signal the state of the breaker contacts and, more particularly, to
arrangements for
actuating the auxiliary switch.
Background Information
It is common for many circuit breakers to be provided with an
auxiliary switch that signals the open or closed state of the circuit breaker
contacts.
Often, the auxiliary switch is offered as an option. For instance, the
auxiliary switch
can be added, if requested, by insertion in a compartment in a primary cover
of the
circuit breaker that is enclosed by a secondary cover. The plunger of the
auxiliary
switch extends through an opening in the primary cover where it is actuated by
a
projection molded on the crossbar that ties the moving contact arms of the
multipole
circuit breaker together. The crossbar necessarily must be stiff to assure
coordinated
movement of the contact arms of all of the poles. Thus, the projection on the
crossbar
which is molded of the same material is stiff and non-compliant.
With this arrangement, there exists the potential for an accumulation of
tolerance stack up within the circuit breaker operating mechanism to provide
too
much or too little travel. This travel may not be sufficient enough to actuate
the
auxiliary switch, or, excessive travel may damage the auxiliary switch. In
previous
instances, customizing/modifying plunger lengths was necessary to accommodate
this
tolerance stack up.
There is, therefore, room for improvement in arrangements for
actuating the auxiliary switches in circuit breakers.
SUMMARY OF THE INVENTION
Aspects of the invention are directed to a multipole circuit breaker in
which an accessory is actuated by an actuator secured to the crossbar and
having a
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compliant finger that actuates and deactuates a plunger of the accessory while
accommodating for variations in travel of the crossbar such as those resulting
from
tolerances and overtravel.
As one aspect of the invention, a circuit breaker comprises: a housing; a
plurality of poles each comprising: separable contacts each comprising a fixed
contact
and a movable contact, and a contact arm assembly comprising a contact arm
having the
movable contact affixed to a distal end and a carrier pivotally mounting the
contact arm
for rotation between a closed position in which the movable contact engages
the fixed
contact and an open position in which the movable contact is separated from
the fixed
contact; a crossbar connecting the contact arm assemblies of the poles
together as a
moving assembly; an operating mechanism coupled to the moving assembly to
simultaneously move the contact arms of the poles between the open and closed
positions; an accessory having a plunger mounted in the housing adjacent to
the
crossbar; and an accessory actuator clip secured to and movable with the
crossbar and
having a forger that engages the plunger to actuate the accessory with the
contact arms in
one of the open and closed positions and that releases the plunger to
deactuate the
accessory in the other of the open and closed positions, the finger being
complaint to
accommodate for variations in travel of the crossbar.
The accessory actuator clip may be molded as a unitary piece from a
compliant material.
The accessory actuator clip may comprise a plurality of hooks that secure
the accessory actuator clip to the crossbar.
'The crossbar may be secured to the carrier of the contact arm assembly of
one of the poles with a staple. The staple may include a pair of legs. The
accessory
actuator clip may be a molded clip that seats over the staple with a pair of
hooks
engaging the pair of legs of the staple.
The accessory actuator clip may include a pair of legs having distal ends.
The staple may include a pair of legs having distal ends. A pair of cleats may
project
inwardly from the distal ends of the legs of the accessory actuator clip. The
legs of the
accessory actuator clip may straddle the legs of the staple. The cleats may
snap under
the distal ends of the legs of the staple to secure the accessory actuator
clip to the moving
assembly.
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The accessory actuator clip may include a U-shape having a base and a
pair of parallel legs. The finger may extend at an angle from the outer
surface of one of
the legs.
As another aspect of the invention, an accessory actuator clip is for a
circuit breaker including a housing, a plurality of poles each comprising:
separable
contacts each comprising a fixed contact and a movable contact, and a contact
arm
assembly comprising a contact arm having a movable contact affixed to a distal
end and
a carrier pivotally mounting the contact arm for rotation between a closed
position in
which the movable contact engages the fixed contact and an open position in
which the
movable contact is separated from the fixed contact, a crossbar connecting the
contact
arm assemblies of the poles together as a moving assembly, an operating
mechanism
coupled to the moving assembly to simultaneously move the contact arms of the
poles
between the open and closed positions, and an accessory having a plunger
mounted in
the housing adjacent to the crossbar. The accessory actuator clip comprises: a
base; a
pair of legs; and a finger extending at an angle from the outer surface of one
of the legs,
wherein the accessory actuator clip is structured to secure to and be movable
with the
crossbar, wherein the finger is structured to engage the plunger to actuate
the accessory
with the contact arms in one of the open and closed positions and to release
the plunger
to deactuate the accessory in the other of the open and closed positions, and
wherein the
finger is complaint to accommodate for variations in travel of the crossbar.
BRIEF DESCRIPTION OF THE DRAWINGS
A full understanding of the invention can be gained from the following
description of the preferred embodiments when read in conjunction with the
accompanying drawings in which:
Figure 1 is an isometric view of a circuit breaker incorporating aspects of
the invention.
Figure 2 is a longitudinal sectional view through the circuit breaker of
Figure 1 showing pertinent parts.
Figure 3 is an isometric sectional view showing pertinent parts of the
circuit breaker of Figure I .
Figure 4 is an isometric view of an accessory actuator clip in accordance
with aspects of the invention.
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Figure 5 is an isometric view illustrating the relationship of the accessory
actuator clip of Figure 4 to an auxiliary switch and to its support.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 illustrates a circuit breaker 1 incorporating aspects of the
invention. The circuit breaker 1 has a housing 3 formed by a base 5, a primary
cover
7 that mates with the base 5, and a secondary cover 9 seated on the primary
cover.
The example circuit breaker 1 has three poles 11A, 11B and 11C, although the
invention is applicable to circuit breakers having two or more poles. The load
conductors 13A, 13B and 13C for these poles are visible in Figure 1. A handle
15 is
used to manually turn the circuit breaker 1 off and on.
Figures 2 and 3 illustrate only pertinent internal parts of the circuit
breaker 1. Each of the poles of the circuit breaker 1, such as the pole 11A,
has
separable contacts 17 in the form of a fixed contact 19 and a movable contact
21. The
fixed contact 19 is mounted on a Line conductor 23, while the movable contact
21 is
affixed to the distal end 25 of a contact arm 27. The contact arm 27 is
supported for
pivotal movement at about an axis 29 by a carrier 31 to form a contact arm
assembly
33. As illustrated by the arrows 35, the contact arm assembly 33 is rotatable
between
a closed position, as shown in Figure 2, in which the movable contact 21
engages the
fixed contact 19 and an open position (not shown) in which the separable
contacts 17
are separated.
The contact arm assemblies 33 of the three poles 11A-11C are joined
together to form a moving contact assembly 37 by a crossbar 39. As is well
known,
an operating mechanism 41, typically coupled to the center pole 11B, operates
the
moving assembly 37 to simultaneously open and close the separable contacts 17
of
each of the poles 11A-11C. The operating mechanism 41 can be actuated manually
by the handle 15 or automatically in response to specified current/time
characteristics
of load current by a trip mechanism 43, again as is well known.
The crossbar 39 is tied to the carrier 31 of each pole 11 by a staple 45.
As shown in Figure 5, the staple 45 has a pair of legs 47 each of which
terminates in a
pair of stakes 49 that extend through holes in the carrier 31 as can be seen
in Figure 3.
The ends of the stakes 49 are spun to secure the staple 45, and therefore, the
crossbar
39 to the contact arm assembly 33.
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As shown in Figure 2, the primary cover 7 of the circuit breaker I has a
compartment 53 in which is received an accessory such as the auxiliary switch
55.
The auxiliary switch 55 is secured in the compartment 55 by the secondary
cover 9
(Figure 1). The auxiliary switch 55 has a plunger 57 that extends downward
into the
cavity 59 where is it actuated by an accessory actuator clip 61 (Figure 3). As
best
seen in Figure 4, the accessory actuator clip 61 is U-shaped having a base
part 63 and
a pair of legs 65 and 67 extending in generally parallel planes from the ends
of the
base part 63. An actuating finger 69 extends at an angle from the outer
surface of the
leg 65. A pair of hooks, such as cleats 71, chamfered at the lateral edges 73
project
inwardly from the distal ends of the legs 65 and 67.
The accessory actuator clip 61 is preferably molded as an integral
piece from a compliant material such as, for example, a polyester resin. It is
secured
on the crossbar 39 by spreading the legs 65 and 67 to straddle the legs 47 of
the staple
45 (Figure 5). When fully seated on the staple 45, the cleats 71 snap under
the distal
ends of the legs 47 of the staple 45 between the stakes 49 to firmly secure
the
accessory actuator clip 61 to the moving assembly 37 (Figure 3). As can be
seen from
Figures 2, 3 and 5, when the contact arm assembly 33 of the pole 11A is in the
closed
position, the actuating finger 69 of the actuator accessory clip 61 (Figure 4)
engages
and actuates the plunger 57 of the auxiliary switch 55. The actuating finger
69 is stiff
enough that it overcomes the spring bias on the plunger 57 to actuate the
plunger, yet
is flexible enough that when the plunger seats, the actuating finger 69 can
flex to
accommodate for overtravel. This overtravel can result from a stackup of
tolerances
in the moving assembly 37 which can result in different angular positions of
the
crossbar 39 when the separable contacts 17 are closed. Additional variations
in the
final position of the crossbar 39 with the separable contacts 17 closed can be
attributed to wear of the fixed and movable contacts 19 and 21. The flexing of
the
actuating finger 69 due to the compliant material from which it is made easily
accommodates for these variations without generating undue stresses.
As mentioned, the accessory in the exemplary embodiment of the
invention is the auxiliary switch 55. Such auxiliary switches are commonly
used to
signal the open/closed state of the separable contacts 17, such as for remote
monitoring or operation.
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As another example of an accessory, a similar microswitch is typically
incorporated into a shunt trip mechanism (not shown), which allows the coil of
the
shunt trip mechanism to be energized only when the separable contacts 17 are
closed.
Such a shunt trip mechanism is variously used for remote tripping of the
breaker and
for electronic tripping, which can include tripping for ground faults and/or
arc faults.
Although example accessories are disclosed, a wide range of circuit
breaker accessories may be employed with the example accessory actuator clip
61.
While specific embodiments of the invention have been described in
detail, it will be appreciated by those skilled in the art that various
modifications and
alternatives to those details could be developed in light of the overall
teachings of the
disclosure. Accordingly, the particular arrangements disclosed are meant to be
illustrative only and not limiting as to the scope of the invention which is
to be given
the full breadth of the claims appended and any and all equivalents thereof.
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REFERENCE NUMERICAL LIST
1 circuit breaker
3 housing
5 base
7 primary cover
9 secondary cover
11 poles A,B,C
13 load conductors
15 handle
17 separable contacts
19 fixed contact
21 movable contact
23 line conductor
25 distal end of contact arm
27 contact arm
29 pivot axis
31 carrier
33 contact arm assembly
35 arrows
37 moving assembly
39 crossbar
41 operating mechanism
43 trip mechanism
45 staple
47 legs of staple
49 stakes
53 compartment
55 accessory auxiliary switch
57 plunger on accessory auxiliary switch
59 cavity in housing
61 accessory actuator clip
63 base of accessory actuator clip
65 leg of accessory actuator clip
67 leg of accessory actuator clip
69 actuating finger
71 cleats
73 chamfers
