US2831085A - Wiring device - Google Patents

Description

April 1953 v. L. CARISSIMI 2,831,085

WIRING DEVICE Filed Jan. 3', 1956 INVENTOR Vincent L.Corlssimi (MKM'I-M ATTORNEY United States Patent WIRING DEVICE Vincent L. Carissimi, Fairfield, Comm, assignor to The Bryant Electric Company, Bridgeport, Conm, a corporation ol: Connecticut Application January 3, 1956, Serial No. 556,954

4 Claims. (Cl. 200-113) My invention relates to a wiring device and, more particularly, to an infinitely variable position electrical switch for controlling the energization of an electrical heating element.

As is well known, it is the present practice to provide electrical switches for controlling electrical heating elements which have a cycling movable circuit making and breaking element for controlling the heat dissipation of the heating element. Such switches are provided with an infinite number of positions up to and including the high or full on position so that the heat dissipation may be infinitely varied. The use of the cycling element is, however, undesirable when the switch is in the full oni position due to the fact that such cycling ele ment, alone or in series with a heater element, is a cur rent carrying member which at the full on position causes a high heat dissipation within the switch. In addition, the use of a cycling member in the full on position requires some positive means to hold the cycling member in the full on position. Heretofore, it has been common practice to mechanically engage the cycling member for such holding which has resulted in stressing the cycling member. Such mechanical stress accompanied with the reduced allowable stress at elevated temperatures has resulted in overstressing the cycling member.

Accordingly, one object of my invention is to provide a shunt brush for a cycling control device.

Another object of my invention is to provide a cycling control device having an infinite number of positions, within limits, the cycling member of which is shunted at oneposition of the device. I I

These and other objects of my invention .will become more apparent upon the following detailed description of a preferred embodiment of my invention when taken in' conjunction with the attached drawings, in which:

Figure'l is a sectional view of a switch constructed in accordance withv the'principles of my invention taken. along theline lI of Fig. 2; and I Fig. 2 is a cross section view of the switch shown in Fig. 1 taken along the line 11-11 thereof. I

It willbe noted that the switch shown in Figs. land 2 is substantially identical to the switch shown in the copending application. Serial No. 556,953, filed concurrently herewith by O. L. Taylor and C. M. Smith entitled. Wiring Device and which has been assigned to the same assignee as this invention. For a more complete descrip-- tion of the construction of many portions of the switch. described herein, theabove-identified application should be consulted. The switch of my construction differs in. that a shunt brush is used to shunt the cycling element in the fullon position of the handle, as is more fully described herein. A

The switch shown in the drawings comprises a rectangular one-piece cup-shaped housing 2 having a base 13, and'integral longitudinally'extending laterally spaced. side walls'sand 9which are connected at their ends by 2,831,085 Patented Apr. 15, 1958 means of laterally extending end walls 12. Housing 2 may be formed from any suitable insulating material and is preferably formed from a molded plastic material which may readily be formed as hereinafter described. As shown, a pair of laterally spaced terminals 4 and 6 are located inwardly adjacent one end wall 12 of housing 2 and a similar terminal 10 is located inwardly adjacent the opposite end wall 12. Terminals 4, 6 and 10 may be made from any suitable electrical conducting material, such as an alloy of copper, and are each provided with integral connector engaging portions which extend through a slot (not shown) in base 13 of housing 2 and outwardly from the outer side of base 13 of housing 2 so that wiring connections may readily be made thereto externally of the housing 2. Such out.- warclly extending connector engaging portions are shown only for the terminals 4 and 6 in Fig. 2; however, terminal 10 is similar thereto. The portions of terminals 4, 6 and 10 which extend inwardly of housing 2 are larger than the slots through which the connector engaging portions extend so that terminals 4, 6 and 10 may readily be located in place by merely inserting the connector engaging portions through the slots in the base 13 and thereafter wedging a portion of the connector engaging portion into firm engagement with the outer surface of base 13. It will also be noted that the inwardly extending portion of terminal 10 is located on approximately the longitudinal center line of housing 2 and extends longitudinally between the end wall 12. T erminals 4 and 6 extend longitudinally between end walls 12; however, they are spaced laterally on opposite sides of the longitudinal center line of housing 2, with terminal 4 being offset toward side wall 8 of housing 2 and terminal 6 being offset toward side wall 9.

Terminals 4 and 6 are adapted to be electrically con nected to terminal 10 by means of generally longitudinally extending brushes 14 and 16, respectively. One end of each brush 14 and 16 is formed to extend adjacent the inwardly located portion of terminal 10 so that brushes 14 and 16 may be electrically and mechanically secured thereto in any suitable manner such as by means of rivets, not shown. Brushes 14 and 16 are formed from any suitable electrical conducting material, such as an alloy of copper which has sufiicient resiliency to bias the opposite free ends of brushes l4 and 16 into engagement with terminals 4- and 6, respectively. The free end of brush to is provided with a laterally extending arcuate surface 15 for engaging the surface of terminal 6 facing side wall 9. Brush 16 is utilized to control a pilot light, and accordingly, it does not carry any substantial amount of current so that such contact engagement is satisfactory. Brush 14 is, however, a line current-carrying member, and in order to minimize arcing damage when brush 14 engages the surface ofterminal 4 facing side wall 9, the opposed portions of terminal 4 and brush 14 are provided with are resistant contacts 17 and 19, respectively, which may be formed from any suitable are resistant material, such as silver or an alloy thereof. Contacts 19 and 17 may be secured to the brush 14 and terminal 4, respectively, in any suitable manner, such as by being riveted thereto.

It will be noted that brush 16 is formed so that the portion adjacent terminal 10 extends sharply toward side wall 9 and thereafter is formed to provide a straight portion 20 which extends toward the terminal 6. As terminal 10 is located on approximately the longitudinal center line of housing 2, it is obvious that brush 16 is offset towards side wall 9. Straight portion 20 of brush 16 extends to each side of the lateral center line of housing 2. and is provided approximately centrally thereon with an integral inwardly extending projection 22. The portion of brush 14. intermediate its fixed and free ends is generally U-shaped with its arms extending outwardly from each other and with its bight portion 24 being located approximately parallel to and inwardly adjacent to the straight portion 26 of brush 16. Bight portion 24 is also offset from the longitudinal center line of housing 2 toward side wall 9 of housing 2.

Brushes 14 and 16 are operated by means of a formed cam 26 which is rotatably supported within the housing 2' and is formed of any suitable insulating material, such as a molded plastic material which may readily be pro vided with the necessary structure as hereinafter described. As shown, cam 26 is provided with a central axially extending circular opening 28 through which an elongated operating shaft 30 extends. Shaft 30 may be formed from any suitable material having sufficient structural strength, such as steel. in order to rotatably support the inner end of shaft 30 within the housing 2, the inner surface of the base 13 is provided with a circular recess 32 in which the circular inner end of shaft 30 is rotatably received. If desired, a boss 34 may be provided which extends inwardly from base 13 of housing 2 for engaging the inner end of cam 26 to support the cam 26 above the inner surface of base 13. In such event recess 32 also extends through boss 34.

The entire open side of housing 2 is enclosed by means of a cover 36 which may be formed of any suitable material, such as steel, and which is secured to the open side or" housing 2 in any suitable manner, such as by means of projections at the sides thereof, not shown, which are deformable to engage cam surfaces on the sides 8 and 9 of the housing 2. Cover 36 is provided with an approximately central opening 21 which is in alignment with the excess 32 and through which the outer end of shaft 36 extends and is freely supported thereby. if desired, the outer end of shaft may be provided with suitable means, such as a slot 38, for securing a handle, not shown, thereto whereby the shaft 30 may readily be rotated in order to accomplish the purposes as hereinafter described.

Although cam 26 may be secured to shaft 30 in numerous satisfactory ways to obtain rotation of the cam 26, as shown, the opening 28 is enlarged radially at its outer end and shaft 39 is also enlarged radially so that the inner end of the enlarged portion of shaft 36 is closely received therein. The enlarged portion of shaft 30 is of a non-circular cross section in order that a catch 42 may be placed thereon and be non-rotatably supported by the shaft 30 so that rotation of shaft 30 causes a corresponding rotation of catch 42. As shown, catch 42 is provided with a pair of inwardly extending lugs 48 which are closely received in inwardly extending recesses 50, only two of which are shown, which extend inwardly from the outer surface of cam 26. Thus, rotation of shaft 30 causes lugs 48 of catch 42 to engage the sides of recesses 50 to cause a corresponding rotation of cam 26. In order to locate catch 42 axially along shaft 30, a suitable stop member 44 may be secured to shaft 30 for engaging the inwardly facing surface of catch 42. Further, a spring member 46 may be located on shaft 30 for biasing the catch 42 into engagement with the stop member 44 which is located between the inwardly facing surface of cover 36 and the outwardly facing surface of catch 42.

As best shown in Fig. l, the inner end of cam 26 is circular in form except for a narrow projection 52 extending radially outwardly therefrom. The inner end of cam 26 is of a size so that it may be freely rotated without engaging the brush 14 adjacent thereto. Projection 52 is of a size that upon such rotation it engages the bight portion 24 of brush 14 to force brush 14 towards side wall 9 and separate the contacts 17 and 19. Such movement of brush 14 also causes the bight portion 24 to engage the inwardly facing end of projection 22 and force the brush 16 out of engagement with the terminal 6. Inasmuch as the brush 14 moves toward the terminal 6, housing 2 is preferably provided with an upwardly extending integral barrier 51 which extends longitudinally between the inner portions of terminals 4 and 6 whereby the free end of brush 14 is prevented from engaging the terminal 6.

As shown, an elongated generally longitudinally extending resilient bimetal element 54 is located inwardly adjacent side wall 8 with the end laterally spaced from terminal 10 being secured to a terminal 56 which is similar in construction to terminal 10. Terminal 56 is secured to base 13 in a similar manner to terminal 10 so that the inner portion extends slightly angularly from the adjacent end wall 12 upwardly toward side wall 8. Eimetal element 54 may be formed from any suitable pair of dissimilar materials having different coefiicients of thermal expansion such as are generally available commercially in the well known manner. One end of bimetal 54 is fixedly secured to the inner portion of terminal 56 in any suitable manner, such as by rivets 57,

only one of which is shown. A contact 58 similar to the contacts 17 and 19, previously described, is secured to the opposite movable end of bimetal 54 in any suitable manner such as by being riveted thereto.

An elongated longitudinally extending resilient bimetal element 60, which is substantially identical to the bimetal 54, is located inwardly adjacent side wall 9 so that it extends generally longitudinally of side wall 9. As shown, the end of bimetal 60 laterally spaced from terminal 56 is pivotally secured to the housing 2, and the opposite movable end of bimetal 60 is laterally spaced from the movable end of bimetal 54. A cross link 62 of any suitable material, such as spring steel, extends laterally between the movable ends of bimetal elements 54 and 60 and is located inwardly adjacent the end wall 12 between the inner surface of end wall 12 and the adjacent terminals 4 and 6. Cross link 62 is pivotally secured to both bimetals 54 and 60 in any suitable manner, such as by forming the ends of the cross link 62 to engage formed slots (not shown) in the movable ends of bitnctals 54 and 60 into which the formed ends of cross link 62 may be inserted. Thus, movement of either bimetal S4 or 60 in either direction causes a corresponding movement in the opposite bimetal 54 or 60 due to the cross connection of cross link 62.

Still another terminal 64, similar to terminals 4, 6, 10 and 56 previously described, is secured to base 13 of housing 2 in the same manner as previously described. Terminal 64 is located laterally between the terminals 10 and 56 and further inwardly toward the center of housing 2. As shown, a composite bimetal element 66 extends inwardly from and longitudinally adjacent bimetal 54 and is secured to the inwardly extending portion of terminal 64 in any suitable manner, such as by rivets 59. Composite bimetal 66 comprises a light bimetal section 68 which is secured to the terminal 64 and a heavier bimetal section 70 which is secured to the bimetal section 68 in any suitable manner, such as by being spot welded thereto. As shown, bimetal section 70 is similar to the bimetals 54 and 60. previously described. While the bimetal section 68 is also formed of two dissimilar materials, in the same manner as bimetal 54 previously described, it is of substantially less thickness than bimetals 54, 60 and 70. A contact 72 similar to the contacts 17 and 19, previously described, is secured to the free end of bimetal section 70 in any suitable manner, such as by riveting, so as to 'be cooperable with the contact 58 on bimetal 54. Although not shown, the portion of bimetal section 68 between terminal 64 and bimetal section 70 has been reduced in width to obtain a more rapid movement into and out of engage ment with contact 58 on bimetal 54 as described in the above identified copending application.

As has been indicated, bimetal 60 is pivotally supported at one of its ends. As shown, housing 2 is provided with an integral projection 71 which extends inwardly at the intersection of side wall 9 with end wall 12 adjacent the terminals and 56. Projection 72 is provided with a surface facing terminal 10in which a generally V- shaped notch 74 is provided so that projection 72 may function as a pivot support. An elongated rigid cam follower 76, which may be formed from any suitable material having sufficient structural strength, such as steel, is provided, which extends generally longitudinally within housing 2 adjacent the side wall 9. One end of cam follower 76 is formed to provide a pair of spaced laterally outwardly extending projections 78, the free ends. of which are freely received within the V-shaped notch 74 in projection 72, so that camffollower 76 is pivotally supported therein. In order that projections 78 are retained within the notch 74, biasing means comprising a generally omega-shaped spring 80 is provided which may be formed from any suitable spring material, such as steel. As shown, a projection 82 is provided on cam follower 76 which extends laterally therefrom toward the side wall 8 and which is located, for convenience'in fabrication, between the projections 78.

Housing 2 is also provided with an integral support 84 between the pivotally supported end of cam follower 76 and terminal 10 which extends inwardly from the base 13 and which has a notch 85 therein facing the pivotally supported end of cam follower 76. With such construction, the opposed arms of spring 80 may be inserted within the notch 85 and the intersection of the projection 82 with the cam follower 76, respectively, so that the arms of spring 80 are forced toward each other when the cam follower 76 is inserted within housing 2. Movement of cam follower 76 toward side wall 9 causes the central portion of spring 80 to be compressed to bias the cam follower 76 toward side wall 8. It, of course, will be appreciated that'in order to provide an initial bias on cam follower 76 the armsof spring 80 are initially stressed toward each other when inserted in position as described.

It will particularly be noted that the opposed bimetals 54 and 60 are located adjacent the inner surface of base 13 and that the cam follower 76 is spaced outwardly from the inner. surface of base 13 so as to be movable transversely across the outeredge of the bimetal 60 heretofore described. In view of such location of cam follower 76, it is provided with an integral portion, not shown, adjacent its pivotally supported end which extends toward the base 13 so that the end of bimetal 60 spaced from the cross link 62 may be secured thereto in any suitable manner, such as by rivets, not shown. Thus, movement of cam follower 76 will cause a movement of thepbimetal 60 which, in turn, as previously stated, will cause a movement of bimetal 54. 7

Although not shown, cross link 62 is provided with an upwardly extending projection approximately centrally thereof, one end of which is engageable with the free end of cam follower 76. Engagement of cam follower 76 and the projection provides a positive off position for the switch. As shown, the central portion of cam follower 76 is offset towards side wall 9 with its free end being formed to extend sharply toward the side wall 8. The central portion of cam follower 76 extends adjacent an irregularly formed cam portion 94 which is an integral portion of cam 26. Engagement between cam portion 94 and cam follower 76 is obtained by means of a screw 95 threadedly engaging the central portion of cam follower 76 and which extends therethrough. It will be noted that the end of screw 95 facing side wall 9 is provided with a slot whereby the relative position between cam follower 76 and cam portion 94 may be varied. In' order to facilitate such adjustment an opening, not shown, is provided in the side wall 9 in alignment with the screw 95.

The construction of the switch heretofore described provides bimetal 54 which cycles into and out of electrical and mechanical engagement with bimetal 56 as is more 6 fully described in the above identified copending application. The above identified copending application also particularly describes and shows the fact that the terminal 56 is electrically connected to a source of suitableelectrical energy so that current flows from terminal 56 through bimetal54, contact 58, contact 72, bimetal 66 and terminal 64 which in turn is connected by means of a suitable electrical conductor to one end of an electrical heating element. Thus, the cycling of the bimetal 54 controls the electrical energy input to the heating element, which due to the cycling of bimetal 54 varies depending upon the position of bimetal 54. With this construction the turning of cam plate 26 to the full on position causes contacts 58 and 72 to remain'in engagement with each other constantly. As the current flows through the bimetal. 54 and bimetal 66, a large amount of heat energy will be dissipated within the switch with the resultant loss of electrical energy at the full on position. In order to prevent such heat dissipation, I have provided a shunt brush which may be formed of any suitable electrical conducting material having sufiicient resiliency, such as an alloy of copper, which is movable to electrically connect terminal 56 to terminal 64 when the cam 26 is in the full on position.

Shunt brush 100 is generally U-shaped with one arm being longer than the other. As shown, the short arm 102 of shunt brush 100 is connected to terminal 56 in any suitable manner, such as by utilizing the rivets 57 previously described. The long arm 104 of shunt brush 100 extends generally longitudinally within housing 2 between the bimetal 66 and the longitudinal center line of housing 2. A suitable electrical contact 106, which is similar to the contacts 17 and 19 previously described, is secured to arm 104 at approximately its midpoint in any suitable manner, such as by being riveted thereto. Contact 106 is cooperable with terminal 64, which cooperation may be provided by utilizing one of the rivets 59 as previously described. Accordingly, as shown, the rivet 59 in lateral alignment with contact 106 may be fabricated from a silver alloy or be silver plated to minimize the arcing damage resulting from its engagement with contact 106.

As shown, the free end of arm 104 of shunt brush 100 extends longitudinally inwardly of housing 2 so as to be spaced outwardly from the path of projection 52 on the inner end of cam 26. The free end of arm 104 is also formed so as to extend below the cam portion 94 so as to be located between the cam portion 94 and the inner surface of base 13. In order to provide means for activating arm 104 of shunt brush 100, cam 26 between its inner end carrying projection 52 and the cam portion 94 is provided with an integral radial outwardly extending projection 110 which is of a radial length greater than projection 52 and less than that portion of cam portion 94 in alignment therewith. Thus, upon rotation of cam 26, projection 110 engages the free end of arm 104 to force arm 104 toward the bimetal 66 so that the contact 106 mounted thereon engages the cooperable rivet 59 on the terminal 64, as shown in dotted lines in Fig. 1. In accordance with my invention, shunt brush 100 is provided with sufficient cross-sectional area and is of a sufliciently high conductivity material so that such engagement of contact 106 with rivet 59 on terminal 64 provides a low resistance electrical path between the terminal 56 and the terminal 64. Such a low resistance path between these terminals shunts the current so that the bimetals 54 and 66 are not heated to any substantial degree. If desired in order to provided a smooth engagement between the projection 110 and the free end of arm 104, an offset portion 112 may be provided at the extreme end of arm 104. Also if desired, arm 104 may be indented towards the arm 102 at approximately its midpoint in order to increase the distance between the separate contacts 106 and 59. Thus, it will be noted that with my invention I have provided a low resistance auxiliary contact system which is separately controllable by the cam 26 so as to shunt the cycling contact assembly for the full on position of the cam 26. It will particularly be noted that such a control has been achieved by using the same terminals of the circuit as are used in the cycling portion of the switch.

Having described a preferred embodiment of my invention in accordance with the patent statutes, it is desired that my invention be not limited to the specific construction illustrated, inasmuch as it will be apparent to those skilled in the art that many modifications thereof may be made without departing from the broad spirit and scope of my invention. Accordingly, it is desired that my invention be interpreted as broadly as possible and that it be limited only as required by the prior art.

I claim as my invention:

1. A wiring device comprising an insulating support, a pair of spaced terminals secured to said support, elongated bimetal elements secured adjacent one end to said terminals, respectively, so as to extend outwardly therefrom in substantially the same direction, operating means movably mounted on said support and including one cam portion for actuating means connected to one of said bimetal elements to cause the other end of said one bimetal element to engage the other end of said other bimetal element, at least one of said terminals being adapted to be connected to a source of electrical energy so that a current flows through said engaged bimetal elements, a resilient conducting member secured to one of said terminals and having an extending end located adjacent the other of said terminals, and said operating means having another earn position engageable with said resilient member upon rotation of said operating means to one position to move said extending portion of said resilient means into engagement with said other terminal whereby said bimetal elements are shunted.

2. A wiring device comprising an insulating support, a pair of spaced terminals secured to said support, an elongated resilient bimetal element secured to one of said terminals so as to extend outwardly therefrom, operating means movably mounted on said support having a cam surface thereon, follower means movably mounted on said support engageable with said cam surface so as to be movable upon movement of said operating means, said follower means being connected to said bimetal element to move the extending portion of said bimetal element into engagement with a contact connected with the other of said terminals so that various pressures are exerted therebetween, a resilient member secured to one of said terminals and having an extending portion located adjacent the other of said terminals,

a second cam surface on said operating means engageable with said resilient member upon movement of said operating means to one position to move said extending portion of said resilient member into engagement with said last-mentioned other of said terminals Whereby said bimetal element is shunted.

3. A wiring device comprising, a support of insulating material, spaced terminals mounted on said support, an elongated bimetal element having one end mounted on one of said terminals and a contact mounted adjacent the other end thereof, a cooperating contact connected with the other of said terminals, manually operable means movably mounted on' said support, means including a resilient member operated by said manual means to move said other end of the bimetal element in a direction to close said contacts selectively under various contact pressures dependent on the amount of movement of said manual means, a movable contact member connected to one of said terminals for movement into and out of engagement with a part connected to the other of said terminals, and said movable contact having a part directly operable by said manual means at a position thereofof maximum pressure on said firstmentioned contacts.

4. A Wiring device comprising, a support of insulating material, spaced terminals mounted on said support, an elongated bimetal element having one end mounted on one of said terminals and a contact mounted adjacent the other end thereof, a cooperating contact connected with the other of said terminals, manually operable means movably mountedon said support, means including a resilient bimetal member operated by said manual means to move said other end of the bimetal element in a direction to close said contacts selectively under various contact pressures dependent on the amount of movement of said manual means, said bimetal elements arranged to deflect in opposing senses in response to a given temperature change to compensate for ambient temperature changes, a movable contact member connected to one of said terminals for movement into and out of engagement with a part connected to the other of said terminals, and said movable contact having a part directly operable by said manual means at a position thereof of maximum pressure on said firstmentioned contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,634,431 Meyers July 5, 1927 2,182,048 Elmer Dec. 5, 1939 2,280,960 Lee Apr. 28, 1942

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