US3575565A

US3575565A - Overtravel device for rotary electric switch

Info

Publication number: US3575565A
Application number: US787926A
Authority: US
Inventors: Paul Silvius
Original assignee: Westinghouse Electric Corp
Current assignee: Westinghouse Electric Corp
Priority date: 1968-12-30
Filing date: 1968-12-30
Publication date: 1971-04-20
Anticipated expiration: 1988-04-20

Abstract

An overtravel device is provided for use with a rotary electric switch when the switch is utilized as an auxiliary control switch and actuated by a linkage mechanism connected to a main device, such as a power circuit breaker. The overtravel device includes a lever attached to the linkage mechanism and rotatably mounted between the legs of a U-shaped bracket which drives the shaft of the auxiliary switch. Rotation of the lever relative to the shaft is limited by leaf springs clamped to the bracket on opposite sides of the lever.

Description

United States Patent [72] Inventor Paul Silviu's Murrysville, Pa. [21] Appl. No. 787,926 [22] Filed Dec. 30, 1968 [45] Patented Apr. 20, 1971 [73] Assignee Westinghouse Electric Corporation Pittsburgh, Pa.

[54] OVER- TRAVEL DEVICE FOR ROTARY ELECTRIC SWITCH 8 Claims, 3 Drawing Figs.

[52] US. Cl 200/153, 74/470 [51] Int. Cl ll0lh 3/48, H01h 21/38 [50] Field of Search ..200/l53.20, 155,47; 74/526,5ll (Cur.), 548, 10.9, 10.7, 470

[56] References Cited UNITED STATES PATENTS 2,352,815 7/ 1944 VanValkenburg ZOO/47X la a 2,542,531 2/ 1951 Jeffrey 74/470 2,704,937 3/ 1 955 Stokes 74/470X 2,782,407 2/1947 VerNoey ..200/ l 5 3.20( UX) 3,055,226 9/1962 Kiessling 74/470X 3,385,129 5/1968 Duncan et al 74/511X Primary Examiner-Robert K. Schaefer Assistant ExaminerRobert A. Vanderhye Attorneys-A. T. Stratton and Clement L. McHale OVER-TRAVEL DEVICE FOR ROTARY ELECTRIC SWITCH BACKGROUND OF THE INVENTION This invention relates, generally, to rotary electric switches of the type described in US. Pat. No. 3,229,052, issued Jan.

11, 1966 to Paul Silvius et al. and assigned to Westinghouse Electric Corporation. More particularly, the invention relates to an overtravel device for use with such a switch when it is utilized. as an auxiliary switch in conjunction with a main device, such as a power circuit breaker. The contact members of the switch described in the aforesaid patent are closed at 30 rotational increments and the span of the contact making is approximately :4". When the switch is utilized as an auxiliary switch it is necessary to provide stop members for limiting the rotational travel of the switch rotor to prevent contact members from being opened when they should not be opened. When connecting a linkage mechanism to the main device to actuate the auxiliary switch it is difficult to so adjust the linkage that it will not attempt to drive the switch beyond its correct position, as determined by a stop member thereby possibly damaging either the switch or the linkage or both. An object of this invention is to provide an overtravel device for use with a rotary electric switch driven by a linkage mechanism.

Another object of the invention is to provide an overtravel device which permits a limited amount of rotational overtravel by an actuating mechanism and returns the mechanism to its normal position when the force causing the overtravel is released.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, a generally rectangular lever which is actuated by a linkage mechanism has one end rotatably mounted on the shaft of a rotary switch. The lever is disposed flatwise between generally rectangular legs of a U-shaped driving bracket clamped to the shaft by a bolt extending between the legs which are slotted longitudinally and have a square opening therein to receive the square shaft. Leaf springs are disposed between the legs of the bracket at opposite sides or edges of the lever. Each spring has an enlarged generally square portion at one end with a hole therein for receiving the clamping bolt, thereby clamping the ends of the springs against the bracket which is fixed; on the shaft. The force applied to the lever is transmitted to the bracket and the shaft through the springs and limited overtravel of the lever relative to the shaft is permitted by the springs when sufficient force is applied through the linkage mechanism. The lever is returned to its normal position by the springs when the force causing the overtravel is released.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, particularly to FIGS. 1 and 2, a

rotary switch r tur tts ow th teinsqmp supporting brackets 11 and 12 with a plurality of stator housing 13 and 14' clamped between the brackets 11 and 12 by means of bolts 15, one of which is shown in FIG. 2. Spacing members 16 are disposed between the stator housing and at the ends of the stator housings. The supporting brackets 11 and 12 may be attached to any suitable supporting structure.

As described in the aforesaid patent, each stator housing contains a plurality of pairs of axially spaced contact members 17 which are angularly or circumferentially spaced at 30 angles around the periphery of the housing. Thus, each stator housing and its contact members constitute one stage of a multistage switch. Additional stages may be provided as desired. As also described in the aforesaid patent, contact rollers (not shown) are carried by a rotor inside the stator housing. Each pair of axially spaced contact members 17 is bridged by a contact roller when the rotor is rotated.

The switch rotor is rotated by a square shaft 18 rotatably mounted in a bearing plate 19 at one end of the switch and in the bracket 12 at the other end of the switch. As also described in the aforesaid patent, rotation of the shaft 18 in either direction may be stopped at a desired position by means of stop pins 21 disposed in circumferentially spaced holes in the bracket 12. The pins 21 are engaged by a projection on a stop plate (not shown) which rotates with the shaft 18 and is disposed inside an end cover 22 retained on the bracket 12 by means of the bolts 15.

As explained hereinbefore, when the switch 10 is utilized as an auxiliary switch in conjunction with a main device, such as a power circuit breaker, and the switch 111 is actuated by a linkage mechanism connected to the main device, it is difficult to so adjust the linkage that it will not attempt to drive the switch rotor beyond its correct position, as determined by the stop means within the switch structure, thereby possibly damaging either the switch or the linkage or both. In accordance with the present invention, an overtravel device 25 is provided for connecting the shaft 18 to a link 26 of a suitable linkage mechanism. As shown more clearly in FIG. 3, the overtravel device 25 comprises a generally rectangular level 31, a generally U-shaped driving bracket 32, a pair of leaf springs 33, a bushing 34, a bolt 35, a lock washer 36, a nut 37 for the bolt 35 and two spacing washers 38.

As shown more clearly in FIGS. 1 and 2, the level 31 has a longitudinally extending slot 41 therein and a plurality of indentions 42 at the upper end for adjustably attaching the link 26 to the lever 31 by means of a clamping plate 43 and a bolt 44. The plate 43 has indentions thereon which mate with the indentions 42 on the lever 31.

As shown more clearly in FIG. 3, the lower end of the lever 31 has an enlarged or thickened portion 45 with a circular opening 46 therein for receiving the cylindrical bushing 34. The bushing 34 has a generally square opening 47 therein for receiving the square shaft 18. Likewise, each leg 48 of the bracket 32 has a generally square opening 49 therein for receiving the shaft 18. Thus, when assembled, the lever 31 is rotatably mounted on the shaft 18 by means of the bushing 34, but the shaft 18 cannot rotate in the opening 49 in the driving bracket 32. The lever 31 is assembled in the bracket 32 flatwise with the enlarged portion 45 substantially filling the space between the legs 48 of the U-shaped bracket. If desired, the lever 31 may be made as a flat strip and a generally U- shaped spacing member may be inserted over the lower end of the lever to take the place of the enlarged portion 45.

In order to transmit force applied to the lever 31 to the shaft 18 through the driving bracket 32 and permit limited overtravel of the lever 31 when rotation of the shaft 18 is stopped, the leaf springs 33 are clamped at opposite sides or edges of the lever by means of the clamping bolt 35. As shown in FIG. 3, the lower end of the generally U-shaped bracket 32 The bracket 32 is so cut that the edges 54 are inclined or tapered inwardly slightly so that upon tightening the bolt 35, the leaf springs are under tension against the lever 31 to form a unit lever arm that flexes when the switch shaft is blocked from rotation by a stop pin in the end bracket. The tighter the bolt 35 is drawn, the greater the spring tension.

As shown in FIGS. 1 and 3, each leg 48 of the bracket 32 has a slot 56 therein extending longitudinally from the opening 49 in the leg. Thus, when the overtravel device is assembled on the shaft 18 and the clamping bolt 35 is tightened, the sides 53 of the enlarged portions of the springs 33 are drawn against the washers 38 to apply pressure on the edges 54 of the bracket 32 to constrict the slot 56 to tighten the bracket 32 on the shaft 18. The narrow portions of the springs 33 are disposed between the legs 48 of the bracket 32 and press against the edges of the lever 31. Thus, the leaf springs 33 clamp the lever 31 and the bracket 32 together as a unit to form a rotating lever arm. Accordingly, the force applied to the lever 31 is transmitted through the springs 33 and the bracket 32 to the shaft 18 to rotate the shaft.

When rotation of the shaft is stopped by means of the stop means, limited overtravel of the shaft in either direction is permitted by the flexing of the springs 33 when the force is sufficient to overcome the resistance of the springs. The lever 31 is returned to its normal position by the springs when the force causing the overtravel is released. In this manner sufficient overtravel is permitted to prevent damaging the switch or the actuating mechanism.

From the foregoing description, it is apparent that the invention provides an overtravel device for a rotary switch which may be manufactured from relatively simple parts which may be readily assembled on the shaft of the switch. The device permits limited overtravel relative to the shaft, and the device is returned to its nonnal position when the force causing the overtravel is released.

Since numerous changes may be made in the abovedescribed construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

lclaim:

1. An overtravel device for an electric switch having a rotatable shaft and stop means for limiting rotation of the shaft, said device comprising a lever having one end mounted on the shaft for rotation independently of the shaft about the axis of the shaft, means for driving the shaft, clamping means attaching the driving means to the shaft, and spring means retained in engagement with the lever and the driving means by said clamping means to transmit force applied to the lever to the shaft through the driving means to rotate the shaft and permit limited overtravel of the lever when rotation of the shaft is stopped by the stop means, said driving means being a generally U-shaped bracket having a pair of legs with aligned openings in its legs for receiving the shaft.

2. The overtravel device defined in claim 1, wherein the legs of the bracket are generally rectangular with a longitudinal slot in each leg extending in opposite directions from the opening for the shaft, and the clamping means is a threaded bolt disposed between the legs of the bracket and applying pressure on the edges of the legs to constrict the slots to tighten the bracket on the shaft.

3. The overtravel device defined in claim 2, wherein the shaft is generally square and the openings in the bracket are generally square.

4. The overtravel device defined in claim 1, wherein the lever is disposed between the legs of the bracket with an opening therein aligned with the openings in the bracket for receiving the shaft.

5. The overtravel device defined in claim 4, wherein the lever is generally rectangular in cross section and is disposed flatwise between the legs of the bracket.

6. The overtravel device defined in claim 4, wherein the spring means are leaf springs disposed at opposite sides of the lever.

7. The overtravel device defined in claim 6, wherein each spring has an enlarged portion at one end engaged by the clamping means to retain it in engagement with the bracket.

8. The overtravel device defined in claim 7, wherein the bracket has slightly inclined edges cooperating with the clamping means to maintain the leaf springs under tension against the lever.