Circuit breaker motor operator variable drive coupling apparatus

Apparatus drivingly couples a rotary motor operator mechanism to a reciprocating circuit breaker operator member such as to provide a braking zone intermediate the end of an operating member charging stroke and the start of an operating member return stroke during which the deactivated motor operator mechanism is brought to a stop without disturbing the operator member in its home position. Apparatus includes a latch for latching the operator member in its home position during the braking zone and a link assembly constructed to accommodate shortening of its effective drive length while a spring absorbs the kinetic energy of the motor operator mechanism. By the conclusion of the braking zone, the operator member is unlatched from its home position, and the spring discharges to propel the operator member to its return stroke while re-establishing the full effective driving length of the link assembly, thereby rendering the operator member charging and return stroke lengths equal.

BACKGROUND OF THE INVENTION 
The present invention relates to motor operator mechanisms having specific, 
but not necessarily limited application to industrial circuit breakers. 
More particularly, the present invention relates to variable drive 
coupling apparatus capable of quickly bringing the deactivated motor 
operator mechanism to a stop while being effectively drivingly decoupled 
from the circuit breaker or other instrumentality. Moreover, the present 
invention is an improvement over the variable drive coupling link assembly 
of commonly assigned, copending E. H. Rask application Ser. No. 051,587, 
filed June 25, 1979, now Pat. No. 4,234,772, the disclosure of which is 
incorporated herein by reference. 
In their application to circuit breakers, motor operator mechanisms are 
utilized in lieu of manual means, such as an operating handle, to charge 
the breaker's spring powered contact operating mechanism preparatory to 
contact reclosure after the breaker has been tripped open. Typically, the 
motion of the motor operator mechanism must be rather precisely tailored 
to a particular breaker's contact operating mechanism. This is 
particularly so with regard to the start and stop positions of the motor 
operator mechanism. Typically, these start and stop positions are 
virtually one in the same, termed a "home" position. Under these 
circumstances, it is essential that the motor operator mechanism stop 
rather precisely in its home position at the conclusion of a charging 
cycle in order that it be in the proper position to start the next 
charging cycle. To achieve this, prior art motor operator mechanisms have 
utilized braking techniques, either mechanical braking or both, which are 
effectuated essentially coincidentally with motor de-energization as the 
motor operator mechanism arrives at its home position. While these braking 
techniques are generally effective in abruptly stopping a motor operator 
mechanism within acceptable limits of its home position, they do indeed 
add cost and complexity to the motor operator mechanism. Moreover, any 
braking technique poses potential field service problems. 
It is accordingly an object of the present invention to provide an improved 
apparatus for variably drivingly coupling a motor operator mechanism with 
an operator member of an instrumentality. 
A further object is to provide variable drive coupling apparatus of the 
above character operating to decouple the motor operator mechanism from 
the operator member at the conclusion of an operating cycle and thus 
eliminate the need to abruptly stop motor operator mechanism at a 
predetermined position. 
Another object is to provide variable drive coupling apparatus of the above 
character operating to automatically establish a resilient lost motion 
coupling between the motor operator mechanism and the operator member at 
the conclusion of each operating cycle and thereby effectuate a braking 
zone during which the deactivated motor operator mechanism is brought to a 
stop without disturbing the position of the operator member. 
Still another object is to provide variable drive coupling apparatus of the 
above character wherein, during the braking zone, the operator member is 
latched in its home position while the kinetic energy of the deactivated 
motor operator mechanism is absorbed, and wherein at the conclusion of the 
braking zone the operator member is unlatched from its home position and 
the absorbed kinetic energy is then discharged to propel the operator 
member into an operating cycle. 
Yet another object is to provide variable drive coupling apparatus of the 
above character operating to automatically compensate for the effects of 
the lost motion connection during each operating cycle and thus achieve 
uniformity of operator member movement. 
A further object is to provide variable drive coupling apparatus of the 
above character which is efficient in design and reliable in operation. 
Other objects of the invention will in part be obvious and in part appear 
hereinafter. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided apparatus for 
variably drivingly coupling a motor operator mechanism with a circuit 
breaker operating mechanism. The circuit breaker includes an operator 
member which is driven through a charging cycle by the motor operator 
mechanism via the variable drive coupling apparatus and the operator 
member is, in turn, drivingly coupled with the breaker spring powered 
operating mechanism to charge same. At the completion of a charging cycle, 
the operator member arrives at a home position. The variable drive 
coupling is then effective to decouple the motor operator mechanism from 
the operator member and thus create a zone during which the deactivated 
motor operator mechanism can be brought to a stop without disturbing the 
operator member in its home position. When the motor operator mechanism is 
subsequently reactivated, the variable drive coupling apparatus 
automatically re-establishes drive coupling with the operator member at 
the end of the zone and it is propelled through its charging cycle. 
More specifically, the variable drive coupling apparatus includes a link 
assembly incorporating a resilient lost motion joint operative to 
accommodate a shortening of the effective driving length of the link 
assembly at the conclusion of each charging cycle. With the arrival of the 
operator member at its home position, latch means is effectuated to hold 
the operator member stationary as the apparatus enters a braking zone. 
Spring means incorporated in the lost motion joint absorbs the kinetic 
energy of the de-activated motor operator mechanism, bringing it to a 
complete stop prior to the conclusion of the braking zone. When the motor 
operator mechanism is reactivated, the apparatus is motivated through to 
the end of the braking zone, by which time the latch means has been 
automatically actuated to release the operator member from its home 
position. The spring means discharges to propel the operator member into a 
charging cycle and, at the same time, re-establishes the full effective 
driving length of the link assembly by taking up the play in the lost 
motion joint. 
Preferably, the operator member is slideably mounted for rectilinear 
movement from its home position through a rearward return stroke and then 
a forward charging stroke back to its home position during each charging 
cycle in response to each revolution of the motor operator mechanism. The 
driving length, which is allowed to shorten at the conclusion of the 
operator member charging stroke to create the braking zone, is restored to 
its full effective length by the spring means when the operator member is 
unlatched from its home position at the conclusion of the braking zone. 
The full effective driving length is then maintained for the remainder of 
the return stroke and throughout the charging stroke. Consequently, the 
braking zone is provided while maintaining the return and charging strokes 
of the operator member of equal lengths. 
The invention accordingly comprises the features of construction and 
arrangement of parts which will be exemplified in the construction 
hereinafter set forth, and the scope of the invention will be indicated in 
the claims. 
For a better understanding of the nature and objects of the invention, 
reference should be had to the following detailed description taken in 
conjunction with the accompanying drawings, in which:

DETAILED DESCRIPTION 
Referring to FIG. 1, the variable drive coupling apparatus of the present 
invention couples a rotary output shaft 10 of a motor operator mechanism 
(not shown) with a reciprocating circuit breaker operator member or slide 
12, such that, with each revolution of the output shaft, the operator 
member is propelled from a home position through a light loaded, rearward 
return stroke and a heavily loaded, forward charging stroke back to the 
home position. The motor operator mechanism may be of the construction 
shown in commonly assigned U.S. Pat. No. 4,042,896, while operator member 
12 may be operatively coupled to charge a circuit breaker mechanism of the 
construction shown in the above-noted copending application Ser. No. 
051,587 (U.S. Pat. No. 4,234,772). Affixed to output shaft 10 is a crank 
arm 14 whose free end is provided with a hole 14a in which is received a 
pin 16 carried adjacent one end of a link 18 included in a link assembly, 
generally indicated at 17. A snap ring 19 captures pin 16 in hole 14a to 
pivotally connect the crank arm to the link. The other end of this link is 
provided with a longitudinally elongated slot 18a in which is received a 
pin 20 carried adjacent the free end of a crank arm 22. Positioned below 
link 18 is a link 24 of link assembly 17 which is provided at one end with 
a hole 24a for receipt of pin 20. The other end portion of this link is 
necked down to create an elongated tang 24b whose free end is slidingly 
received in a slot 18b formed in the bent down end portion 18c of link 
situated beyond pin 16. A compression spring 26 is received on tang 24a 
and is captured between the shoulders 24c of link 24 and bent down end 
portion 18c of link 18. As seen in FIGS. 1 and 3, pin 20 is shouldered 
such that link 24 is captured on its larger diameter lower portion by a 
snap ring 25, while link 18 is captured on its reduced diameter upper 
portion by a snap ring 26 and intervening spacer washer 27. 
As best seen in FIG. 3, crank arm 22 is secured to an upper plate 30a of a 
hub 30 rotatably mounted in an opening 32a formed in an insulative breaker 
cover member 22. A lower plate 30b of the hub carries a depending, 
eccentric drive pin 34 which is received in a laterally elongated slot 12a 
formed in operator slide 12, as seen in FIG. 2. A latch 36, best seen in 
FIGS. 1 and 2, is pivotally mounted by a horizontal shaft 37 and is biased 
by a torsion spring 38 to swing into engagement with a notch 22a formed in 
an arcuate edge segment of crank arm 22, thereby latching the crank arm 
against rotation when operator slide 12 arrives in its home position. A 
latch release arm 40 is pivotally mounted on the upper end of a vertical 
shaft 41 and includes an upturned tab 40a at its free end which is acted 
upon by the link assembly 17 to disengage latch 36 from notch 22a. 
As will be seen in the following description in conjunction with FIGS. 2 
and 4 through 6, a motor operator mechanism charging cycle is executed by 
swinging crank arm 14 through a full 360.degree. revolution. During the 
initial portion of each crank arm 360.degree. revolution, operator slide 
12, once unlatched from its home position of FIG. 2, is propelled in the 
direction of arrow 44 through a return stroke. During the concluding 
portion of each 360.degree. revolution, slide 12 is driven in the 
direction of arrow 45 (FIG. 6) through a charging stroke back to its home 
position. As will be seen, link assembly 17 acts on pin 20 to provide a 
spring biased lost motion coupling between crank arms 14 and 22 which is 
effectuated at the conclusion of the slide charging stroke to decouple 
crank arms while the slide is latched in its home position. This lost 
motion coupling provides a braking zone during which the kinetic energy of 
the motor operator mechanism, which is then deactuated by a normally 
closed switch 46 (FIG. 2) being actuated in response to the arrival of 
slide 12 in its home position, is absorbed by spring 26. The motor 
operator mechanism is thus quickly brought to a stop while the operator 
slide is latched in its home position achieved at the conclusion of its 
charging stroke. By virtue of this braking zone, the necessity for special 
braking provisions to abruptly stop the rotation of the motor output shaft 
precisely at the conclusion of a charging cycle are rendered unnecessary. 
This contributes a distinct advantage in terms of design efficiency and 
field reliability. Paradoxically, it will be seen that this coasting zone 
is achieved while maintaining equal clockwise and counterclockwise throws 
of crank 22, and thus the lengths of the return and charging strokes of 
operator slide 12 are equal. 
The variable drive coupling parts are shown in FIG. 2 with the axes of 
output shaft 10, pin 16 and pin 20 in alignment along a center line 50. 
Since pin 16 is aligned on the opposite side of output shaft 10 from pin 
20, crank arm 22 has arrived at the end of its counterclockwise throw, and 
operator slide 12 has reached its home position at the end of its forward 
charging stroke. It is noted that pin 20 is bottomed against the left end 
of slot 18a in link 18, and edge notch 22a in crank arm 22 is aligned with 
latch 36; the latter being swung into engagement therewith by torsion 
spring 38. Although the motor operator mechanism has been deactivated by 
the actuation of switch 46, its kinetic energy rotates crank arm 14 in the 
counter-clockwise direction away from center line 50. Since the latched 
crank arm 22 can not move, pin 20 moves away from the left end of slot 18a 
and link assembly 17 is simply swung in the counterclockwise direction. 
With the resulting shortening of the link assembly driving length 
(distance between pins 16 and 20), spring 26 is compressed to effectively 
absorb the kinetic energy of the deactivated motor operator mechanism and 
quickly bring it to a complete stop. There is thus provided a resilient 
lost motion connection between crank arm 22 and link assembly 17 effective 
in creating a braking zone 51 through which crank arm 14 may revolve as 
the lost motion connection yields to absorb the kinetic energy of the 
deactivated motor operator mechanism. The motor operator mechanism is thus 
quickly braked to a stop, well before the end of the braking zone 
determined by the length of slot 18a in link 18. 
The utilization of a resilient lost motion coupling in combination with 
latching of the operator slide in its home position is deemed an 
improvement over the variable drive coupling assembly of the above-noted 
Rask copending application, wherein a lost motion coupling is utilized to 
create a coasting zone during which the motor operator mechanism is simply 
permitted to coast to a stop without disturbing the operator slide in its 
home position. With the latter approach, it has been found on occasion 
that the motor operator mechanism coasts beyond the coasting zone before 
coming to a stop, resulting in undesired displacement of the operator 
slide from its home position. 
From FIG. 4, it is seen that as link assembly 17 is swung in the 
counterclockwise direction during the braking zone, it picks up latch 
release arm 40, swinging it also in the counterclockwise direction. In the 
process, this arm progressively pushes latch 36 out of notch 22a. However, 
the motor operator mechanism is braked to a stop by the compression of 
spring 26 before link assembly 17 achieves its position seen in FIG. 4. 
Thus latch 36 remains lodged in notch 22a to continue latching the 
operator slide in its home position. When a charging cycle is called for, 
the motor operator mechanism is activated, and crank arm 14 is revolved 
through the remainder of the braking zone. The link assembly is swung in 
the counterclockwise direction, as is arm 40 to eventually effect complete 
disengagement of the latch from its notch. To eliminate interference, the 
configuration of arm 40 is such that complete disengagement of latch 36 
from notch 22a is effected prior to the conclusion of the braking zone 51 
defined by the bottoming of pin 20 against the right end of slot 18a in 
link 18. It will be appreciated that, with the removal of the latch, 
spring 26 is free to discharge, which it does, in process propelling crank 
arm 22 in the clockwise direction to start operator slide 12 out from its 
home position into a return stroke. The discharge of the spring also 
restores the link assembly to its full effective driving length with pin 
20 bottomed against the left end of link slot 18a which is sustained by 
the spring throughout the clockwise throw of crank arm 22 to the 
conclusion of the operator slide return stroke where the parts assume 
their positions seen in FIG. 5. 
With continued counterclockwise rotation of crank arm 14 by the motor 
operator mechanism from its position seen in FIG. 5, it is seen that pin 
20 is bottomed against the left end of slot 18a in link 18, and crank arm 
22 is pulled through its counterclockwise throw pursuant to propelling 
operator slide 12 in the direction of arrow 45 (FIG. 6) through its 
forward charging stroke. When crank arm 14 swings back around to its 
position seen in FIG. 2, bringing the axis of pin 16 back into alignment 
with center line 50, the charging stroke is concluded. Slide 56 is thus 
returned to its home position, latch 36, which has been riding against the 
arcuate edge segment of crank arm 22 throughout the charging cycle, swings 
into engagement with notch 22a, and switch 46 is actuated to deactivate 
the motor operator mechanism. The motor operator mechanism is braked to a 
stop by spring 26, as crank arm 14 revolves into the braking zone. 
It will be appreciated that the operational effect of the link assembly can 
be provided in other ways to achieve the desired braking zone. For 
example, the spring biased, lost motion coupling may be provided at the 
connection of the link assembly with crank arm 14, rather than with crank 
arm 22, as specifically disclosed herein. Also, the latch may latchingly 
engage the operator slide directly or an element of hub 30 pursuant to 
latching the slide in its home position during the braking zone. 
It will thus be seen that the objects set forth above, among those made 
apparent in the preceding description, are efficiently attained and, since 
certain changes may be made in the above construction without departing 
from the scope of the invention, it is intended that all matter contained 
in the above description or shown in the accompanying drawings shall be 
interpreted as illustrative and not in a limiting sense.