US2798908A

US2798908A - Enclosed electric switch

Info

Publication number: US2798908A
Application number: US465164A
Authority: US
Inventors: Stanley L Frank; Zipay John
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1954-10-28
Filing date: 1954-10-28
Publication date: 1957-07-09
Anticipated expiration: 1974-07-09

Description

July 9, 1957 s. L. FRANK ET AL ENCLOSED ELECTRIC SWITCH Filed Oct. 28, 1954 Fig.3.

Fig.2.

Fig.4.

INVENTORS Ston'ey L.Fronk and John Zipuy ATTORNE United States Patent Pub ENCLOSED ELECTRIC SWITCH Stanley L.. Frank, Beaver, and lohn Zipay, Daugherty Township,,.Beavelr- County, Pa., assiguors to Westinghouse Electric Corporation, East: Pittsburgh, Pin, a corporation oiiPenusylvania- Application October 28, 1954, Serial No. 465,164

7 Claims. (Cl. 2001-48) Our invention relates, generally, to electric switches and, more: particularly, to switches oi the rotary selector type which are enclosed in metal. housing having, re moval; covers.

Several; manufacturers. build. a line of. switches in which each switch. comprises. an. operating, unit, or operator, having, manually operableswitch actuating; means and a. switch uit, orcontactblock, containing the-contactmembers which are actuated by the operating unit. Theoperating unit .and the switch unit may be secured? together in. a. number of different relations. The. switch units. are adapted to, be used: with operating units 0t different types. Furthermore, the. switch units may be, either. single or doublepole, and they have contacts which may be interchanged and supported in different ways. Thus, switches for a wide variety of applications may be readily assembled from a limited. number of standardized components- When; such switches. are. utilized for machine tool and other heavy-duty applications, the operating units, are constructed to prevent the. passage. ofi oil, coolant, cut.- ting compound or water, and the. switch units or contact blocks are .mountedin a Iiquidtight. enclosure-haying aremovable. cover. The, contact block is mounted in the enclosure, and. the operator is so. mounted onthe cover that it is separated from the. contact block, when the cover is, removed.

Here-tofore, it has not. been. possible to remove the cover of an enclosure containing switches having operators of the. rotary selector type without causing false operation of all switch. units actuated to. lmlf the: fulldown positions. This. is. true because removal of the cover includes removal. of the selector switch operator which contains. the cam utilized to actuate. the. spring-- biasedplungers which, in turn, actuate the movablecontact. members. of the switch unit. When.- the: cover isremoved the contact members are biased totheir upper-- most, position in, the contact block, thereby causing: im proper operation of the machines controlledby the switches-unless the service power, has been previously disconnected- An. object: of our invention is. to provide; a switch as-. sembly inwhich the: operating unit and the switch unit may-be separated without permitting a change in the. position. of contact members previously actuated by the. operating unit.

Another object of our invention is. to provide an. em closed switch assembly which does; not require close manufacturingtolerances between the: cover on which the. operating unit is mounted and the box inwhich the. contact. block is mounted.

A. more general object of our invention is to. provide asw-itch assembly which shall be simple. and eificient in operation. and which may be economically manufactured and installed.

Other objects. of the invention will be. explained fully hereinafter or will be apparent to those skilled in. the. art. In accordance with one embodiment of the invention,

a cam which depresses spring-biased plungers to. actuate contact members in. the. contact block of a switch is. attached to; the. contact-block by means of a bracket which functions as. a thrust bearing for the rotating cam. An operating shaft: extends through an extruded portion. in thebracket into: the cam and; is. removable with the. cover. for the enclosure without disturbing the cam which re.- mains in the positiontowhich: it-;was.1astactua;tedi Therefore, the; contact membersremain in the position to: which they were actuated prior to; removal of the cover.

For a better; understanding of; the nature. and objects. of the invention, reference may be had to the following. detailed description, taken in conjunction: with the ac.- companying drawing, in which:

Figure, l is. a: view, partly in elevation and partly in section, of. aswitch assembly embodying the principal features of the: invention;

Fig. 2 isv a View of the contact block looking in. the direction indicated by the line IsL-I;I in Fig. 1;

Fig. 3 isa developed. view of the; operating-cam utilized in. the switch, and- Fig. 4 is a view in elevation of the operating cam Referring to, the drawings, and. particularly to; Fig. 1, thestructure. shown therein comprises a box: or enclosure 10,.Qn1y aportion of which is shown. The enclosure 10, is. preiierably a die-casting and has. a removable cover 11. The. cover 11 may be retained on the box 10 by means ojfi screws (not shown).

The box v10. may contain one or more switches; eachof which comprises.anoperating' unit 12 and a switch. unit 13,. The operating unit12 is of the rotary selector; type and,. inv general, may be constructed, similar to, the rotary selector form of device described in Patent 2,669,616 issued February 16, 1954, to S. L. Frank.

As shown, theoperating unit. 12 comprises a tubular supportingsleeve 14 having a flange 15. on itslower end. The sleeve 14. is disposed. in an opening in the cover. 11 and is retained, in position by a clamping ring 16 which is threadedonto the sleeve 14. The ring 16 is drawnagainst an indicating washer 17 disposed on top. of the cover 11. Asealing disc 18, composedof rubber or other suitable resilient material, is. provided between the flange 15 and the lower side of the cover 11.. When the ring. 16 is tightened against the washer 1 7. liquids, are prevented from enteringthe enclosure around the sleeve 14. A positioning pin 19 is provided in the flange. 15 and is disposed in an aperture in the cover 11 to position the operating unit properly on the cover 11.

The sleeve 14* has a transverse web 21 with an outward'l'y extending flange 22 formed integrally therewith- The flange 22- constitutes a bearing for a rotatable operating shaft 23. An operating head 24 is secured to the upper-endof' the shaft 23. The head 24 is preferably composed of a material which may be, molded onto the shaft 23. A compression spring 25 is disposed between the head 24 and a retainer disc 26 which engages a sealing'disc 27'of rubber or other resilient material disposed between the upper end of the flange 22 and the retainer disc 26. In this manner liquids are prevented from passing around the shaft 23- into the interior of the switch unit.

The shaft 23 and the operating head 24 are retained in the operating unit by a horseshoe-shaped washer 28 which is disposed in a groove 29 in the shaft 23 and engages the bottom side of the web 21. A ball detent 31, which is biased upwardly by a compression spring 32, enters notches 33 provided in the lower edge of a skirt 34 on the operating head 24 -to releasably retain the operating head in predetermined operating'positions.

The switch unit 13 may be generally of the type described in the aforesaid Patent 2,669,616. As shown, it comprises a contact block 35 which is preferably molded from a suitable insulating material. The block 35 is attached to the bottom wall of the enclosure by means of screws 30 which are threaded into the enclosure.

The block 35 is provided with recesses in which are disposed upper and lower pairs of contact members 36 having terminal screws 37 therein for connecting electrical conductors to the switch unit. A bridging contact member 38 which is actuated by a plunger 39 is disposed to bridge the upper pair of contact members 36 when in its uppermost position. The contact member 38 bridges the lower pair of contact members 36 when in its lowermost position. A similar bridging contact member which is actuated by another plunger 39 is disposed in the opposite side of the contact block 35 and engages other contact members 36 in a similar manner. The bridging contact members 38 and the plungers 39 are biased upwardly by springs 41 disposed in the contact block 35.

The plungers 39 are actuated downwardly by a rotatable cam 42. The cam 42 is retained on the contact block 35 by means of a generally U-shaped bracket 43 which is attached to the block 35 by the screws 30. The bracket 43 has an extruded portion 44 with a centrally disposed opening 45 therein. The cam 42 has a recess 46 therein for receiving the extruded portion 44 of the bracket 43.

The cam 42 is biased upwardly against the bracket 43 by the plungers 39 which, in turn, are biased upwardly by the springs 41. Thus, the bracket 43 functions as a thrust bearing for the cam 42 with the extruded portion 44 retaining the cam 42 in a position in which an opening 47 through the cam is in alignment with the opening 45 in the bracket 43. As shown most clearly in Fig. 2, the opening 47 is square or of other irregular shape. It is adapted to receive the lower end 48 of the operating shaft 23, which end is also square in shape as shown in Fig. l or matches the shape of the opening 47.

As shown by the broken lines in Fig. 1, the sleeve 14 fits over the bracket 43 and the square end 48 of the shaft 23 is inserted into the opening 47 in the cam 42 when the cover 11 is closed on the enclosure 10. The cam 42 may then be rotated by manually rotating the operating head 24.

As shown in Figs. 3 and 4, the cam 42 has a high point surface 51, an intermediate point surface 52 and a low point surface 53. The

surfaces

51 and 52 are joined by sloping surfaces 54 and the

surfaces

52 and 53 are joined by sloping surfaces 55. Thus, when the cam 42 is rotated the bridging contact members 38 are actuated by the plungers 39 to positions determined by the angular position of the cam. When the cam 42 is in its intermediate position the contact members 38 are midway between the upper and lower pairs of contact members 36.

As previously explained, it is desirable to be able to remove the cover 11 from the enclosure 10 for inspection purposes without disconnecting the control power from the switch unit contained within the enclosure and without disturbing the position to Which the contact members of the switch unit have been actuated. This was impossible with enclosed switches of prior constructions since the operating cam was removed with the cover, thereby permitting the movable contact members of the switch unit to return to the uppermost positions to which they are biased by the springs in the switch units.

As described hereinbefore, the cover 11 in the present structure may be removed and the end 48 of the shaft 23 disengaged from the cam 42 without changing the angular position of the cam. Therefore, the contact members of the switching unit remain in the position to which they were last actuated prior to the removal of the cover 11 and the operating unit 12. Likewise,

' the cover and the operating unit may be reinstalled without disturbing the position of the cam 42 and the contact members of the switch unit. Thus, the electrical equipment controlled by the switch may be kept running without its operation being changed.

The present structure has the additional advantage of not requiring close manufacturing tolerances between the cover 11 and the enclosure 10. The method of engagement between the end of the shaft 23 and the cam 42 does not require that the end of the shaft be fully inserted into the cam 42. Therefore, the height of the side walls of the enclosure 10 on which the cover 11 is mounted does not need to be maintained to an exact dimension.

From the foregoing description, it is apparent that we have provided an enclosed switch assembly which permits the operating unit and the switch unit to be separated without causing a change in the position of the contact members of the switch unit. Thus, the enclosure which contains the switch unit may be opened without disturbing the circuits established through the switch unit and without causing improper operation of the machine or the other device controlled by the switch. The present structure is particularly suitable for applications requiring that liquids be prevented from entering the enclosure containing the switch unit, but is not necessarily limited to such applications.

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 matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, a spring-biased plunger slidably disposed in the switch unit for actuating the movable contact member of the switch unit, a cam rotatably mounted on the switch unit for depressing the plunger, bearing means on the switch unit for counteracting the thrust of the plunger on the cam, an operating unit mounted on said cover and having a rotatable shaft engaging the cam when the cover is in its closed position on the enclosure, said shaft being separable from the cam when the cover is removed from the enclosure, and operating means for rotating said shaft to rotate said cam when the cover is on the enclosure.

2. In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, spring-biased means disposed in the switch unit for actuating the movable contact member of the switch unit, rotatable cam means mounted on the switch unit for actuating said spring-biased means, bearing means on the switch unit for positioning the cam means, an operating unit mounted on said cover and having a rotatable shaft engaging the rotatable cam means when the cover is in its closed position on the enclosure, said shaft being separable from the rotatable means when the cover is removed from the enclosure, and manually operable means for rotating said shaft to rotate said rotatable means.

3. In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, a spring-biased plunger slidably disposed in the switch unit for actuating the movable contact member of the switch unit, a cam rotatably mounted on the switch unit for depressing the plunger, a bearing bracket attached to the switch unit to retain the cam in position, an operating unit mounted on said cover and having a rotatable shaft engaging the cam when the cover is in its closed position on the enclosure, said shaft being separable from the cam, when the cover is in its closed position on the enclosure,

i said shaft being separable from the cam when the cover is removed from the enclosure, and operating means secured to the shaft to rotate said cam.

4. In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, a spring-biased plunger slidably disposed in the switch unit for actuating the movable contact member of the switch unit, a cam rotatably mounted on the switch unit for depressing the plunger, a bearing bracket attached to the switch unit to retain the cam in position, an operating unit mounted on said cover and having a shaft rotatably mounted therein with one end engaging the cam when the cover is in its closed position on the enclosure, said end of the shaft being withdrawn from the cam when the cover is removed from the enclosure, and an operating head secured to the other end of the shaft to rotate said cam.

5. In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, a spring-biased plunger slidably disposed in the switch unit for actuating the movable contact member of the switch unit, a cam rotatably mounted on the switch unit for depressing the plunger, a bracket attached to the switch unit, said bracket functioning as a bearing to retain said cam in position, an operating unit mounted on said cover and having a shaft rotatably mounted therein, one end of said shaft extending through said bracket to engage the cam when the cover is on the enclosure, said end of the shaft being withdrawn from the cam when the cover is removed from the enclosure, and manually operable means secured to the other end of the shaft to rotate said cam.

6, In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, a spring-biased plunger slidably disposed in the switch unit for actuating the movable contact member of the switch unit, a cam rotatably mounted on the switch unit for depressing the plunger, a bracket attached to the switch unit, said bracket functioning as a thrust bearing to retain said cam in position and to resist the force of said plunger against the cam, an operating unit mounted on the cover and having a shaft rotatably mounted therein, one end of the shaft extending through said bracket into the cam when the cover is on the enclosure, said end of the shaft being withdrawn from the cam when the cover is removed from the enclosure, and an operating head secured to the other end of the shaft to rotate said cam.

7. In a switch assembly, in combination, an enclosure having a removable cover, a switch unit mounted on one wall of the enclosure and having a movable contact member, a spring-biased plunger slidably disposed in the switch unit for actuating the movable contact member of the switch unit, a cam rotatably mounted on the switch unit for depressing the plunger, a bracket attached to the switch unit, said bracket functioning as a thrust bearing to retain said cam in position and to resist the force of said plunger against the cam, said bracket having an extended portion with an opening therethrough, said cam having a recessed portion for receiving the extruded portion of the bracket, said recessed portion having a centrally disposed square opening in alignment with the opening in the bracket, an operating unit mounted on the cover and having a shaft rotatably mounted Itherein, said shaft having a square end extending into the square opening in the cam when the cover is on the enclosure, said end of the shaft being withdrawn from the cam when the cover is removed from the enclosure, and manually operable means secured to the other end of the shaft to rotate said cam.

References Cited in the file of this patent UNITED STATES PATENTS