US3299238A

US3299238A - Push button switches having wiping contact between a flexible contact blade and an apertured contact member

Info

Publication number: US3299238A
Application number: US399626A
Authority: US
Inventors: Jesse M Cobb
Original assignee: Indak Manufacturing Corp
Current assignee: Indak Manufacturing Corp
Priority date: 1964-09-28
Filing date: 1964-09-28
Publication date: 1967-01-17
Anticipated expiration: 1984-01-17

Description

Jan. 17, 1967 J. M. COBB 3,299,238

PUSH BUTTON swrrcnms HAVING WIPING CONTACT BETWEEN A FLEXIBLE CONTACT BLADE AND AN APERTURED CONTACT MEMBER Filed Sept. 28, 1964 2 Sheets-Sheet 1 54 INVENTOIZ Jesse M. Cobb Jan. 17, 1967 J M COBB 3,299,238

PUSH BUTTON SWITCHES HAVING WIPING CONTACT BETWEEN A FLEXIBLE CONTACT BLADE AND AN APERTURED CONTACT MEMBER Filed Sept. 28, 1964 2 Sheets-Sheet 2 FIG. 6

INVEN 70/2 Jasse M. Cobb United States Patent f 3,299,238 PUSH BUTTON SWITCHES HAVING WlPllNG CUN- TACT BETWEEN A FLEXIBLE CONTACT BLADE AND AN APERTURED CONTACT MEMBER Jesse M. Cobb, Glenview, lll., assignor to indair Mannfacturing Corp, Northbroolr, ill., a corporation of lilinors Filed Sept. 28, 1964, Ser. No. 399,626 17 Claims. (Cl. 2tl0l59) This invention relates to electrical switches and pertains particularly to push button switches or other similar switches in which the operating member is moved against the force of a spring which is effective to return the operating member to its original position when the operating member is released. It will be understood, however, that many of the features of the present invention are applicable to other types of switches.

One object of the present invention is to provide a new and improved push button switch which is closed when the switch is in its initial position. Such switches are useful for many purposes. In automotive service, such switches are frequently used for turning on one or more lights when a door is opened, and for energizing a signal lamp or the like when a control pedal or lever is operated.

A further object is to provide a new and improved push button switch which is constructed so as to insure that a good electrical contact will be established when the switch is closed, even after the switch has been used for a long time and has been operated through a great many operating cycles.

Another object is to provide a new and improved push button switch in which a wiping action is provided between the fixed and movable contacts of the switch so as to insure that the contacts will be kept free of corrosion and dirt, whereby good electrical contact willbe assured.

A further object is to provide a new and improved push button switch in which the movable contact has a spring blade which is movable into wiping engagement with the fixed contact.

It is a further object to provide such a new and improved switch in which the spring blade angles outwardly from a generally cylindrical operating member and is engageable with the inside of a circular opening in the fixed contact member, the push button member being slidably received in such circular opening.

Another object is to provide a new and improved switch in which the fixed contact member is combined with a mounting frame of highly advantageous construction.

A further object is to provide a new and improved push button switch which is highly efficient and reliable, yet is extremely low on cost.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a push button switch to be described as an illustrative embodiment of the present invention.

FIGS. 2 and 3 are front and rear elevational views of the push button switch of FIG. 1.

FIG. 4 is an enlarged longitudinal section, taken generally along the line 4-4 in FIG. 2.

FIG. 5 is an elevational view of the terminal and lead adapted to be connected to the switch of FIG. 1.

FIG. 6 is a top view of the switch of FIG. 1.

FIGS. 7 and 8 are enlarged transverse sections taken generally along the lines 77 and 8-8 in FIG. 4.

FIG. 9 is an elevational view of a modified push button switch.

FiG. 10 is a front view of the switch of FIG. 9.

FIG. 11 is a bottom view of the switch of FIG. 9.

As already indicated, FIGS. 18 illustrate an electrical switch 26 which is intended primarily for automotive service, but will find a wide variety of uses. The switch 26 is especially well adapted for use as a door switch, adapted to turn one or more lights on when the door is opened. Such switches are commonly used in connection with the doors of automobiles and other vehicles.

The switch is also highly advantageous for use in connection with a control pedal or lever, such as a brake pedal, for the purpose of energizing a signal lamp or the like when the pedal is operated. As will be discussed in detail shortly, the modified switch of FIGS. 9-11 is especially well adapted for such service, as a brake switch or the like.

The switch of FIGS. 1-8 comprises an operating member 22 which is slidably mounted in a supporting frame 24. It will be seen that the operating member 22 projects forwardly from the frame 24 and serves as a push button or plunger. Preferably the operating member 22 is generally cylindrical in shape and is made of plastic or other electrically insulating material. However, other suitable materials may be employed if desired.

The il ustrated frame 24 is preferably made of metal, such as sheet steel, for example. The illustrated frame 24- is made in two parts, comprising a generally U-shaped bracket 26 and a generally disc-shaped ferrule 28. The bracket 26 has two identical side legs 30. A rear leg 32 extends between the rear ends of the side legs 39. The operating member or plunger 22 is slidably received in a circular opening 34 which is formed in the rear leg 32. Thus, the leg 32 serves as a rear bearing for the plunger 22. A forwardly projecting generally cylindrical flange 36 is formed on the rear leg 32 around the opening 34 to provide a smooth bearing surface for the plunger 22.

The front ends of the side legs 3% are formed With diametrically opposite outwardly projecting arms or flanges 38 having semi-circular outer portions 40 to which the ferrule 28 is connected. The outer edge of the ferrule 23 is formed with an L-shaped annular flange 42 which is clinched or turned behind the semicircular portions at).

It will be seen that the operating plunger 22 is slidably received in a substantially circular opening 44 which is formed centrally in the ferrule 28. A rearwardly projecting substantially cylindrical flange 46 is formed on the ferrule around the opening 44 to provide a smooth bearing surface for the plunger 22. Thus, the flange 46 acts as a front bearing for the operating plunger 22.

PEG. 4 illustrates the manner in which the frame 24 may be mounted in a hole 48 formed in a panel or plate St The side legs 30 extend through the hole 48, while the outer flange portion 42 of the ferrule 24 engages the front side of the panel 59. Detent springs or clips 52 are struck outwardly from the side legs 30 to engage the plate 50 around the hole 48 so as to retain the frame 24 in the hole. It will be seen that each spring 52 angles outwardly and forwardly from the rear portion of the corresponding side leg 30. The front portion of each spring 52 is turned inwardly at an angle to form a ramp or detent portion 54 which engages the rear portion of the panel 50 around the hole 43. Each spring 52 is formed with openings or slots 56 and 53 in its front and rear portions.

When the frame 24 is pushed rearwardly through the opening 48 in the panel 50, the springs 52 engage the inside of the opening and are flexed inwardly. As the rearward movement of the frame is completed, the flange 42 engages the front side of the panel 50, and the springs 52 snap outwardly so that the ramp or detent portions 54 will securely retain the frame 24 in the hole 48. Greater rigidity is imparted to the side legs 30 by flanges 60 which are formed along the edges of the side legs.

It will be seen that the outside of the operating member or plunger 22 is formed with an annular shoulder or enlargement 62. A coil spring 64 is compressed between the rear side of the shoulder 62 and the front side of the rear leg 32. Thus, the spring 64 urges or biases the plunger 22 forwardly. The front side of the shoulder 62 is engageable with the flange 46 on the ferrule 28 to limit the forward movement of the plunger 22. The plunger 22 may be pushed rearwardly against the resilient biasing action of the spring 64.

The rear bearing member 32 of the frame 24 also serves as the fixed electrical contact member of the switch 20. Thus, the switch is particularly applicable to electrical circuits in which one side is grounded. In the present case, the frame 24 is normally grounded through the mounting panel 50. Such circuits are commonly used in automotive service. For other types of service, the fixed contact member may be insulated from ground.

It will be seen that the operating member or plunger 22 carries a movable contact member 66 having a contact blade or spring 68 which is engageable with the fixed bearing or contact member 32. The illustrated contact member 66 is mounted within an axial bore or cavity 70 formed in the plunger 22. It will be understood that the plunger 22 may be molded from plastic material and that the bore '70 may be formed as part of the molding operation.

The illustrated contact member 66 is generally in the form of an elongated channel which is U-shaped in cross section. Thus, the contact member 66 has a pair of side flanges 72 with a base portion or wall 74 extending therebetween. The contact member 66 may be formed from spring brass or other suitable material. To retain the contact members 66 in the bore 70, the upper edges of the side flanges 72 are formed with a series of teeth or serrations 76, similar to saw teeth, adapted to dig into the plunger 22 within the bore 70. Longitudinal shoulders or ridges 78 may be formed on the plunger 22 within the bore 72 for emgagement by the saw teeth '76. It will be seen that the individiual saw teeth 76 are angled rearwardly so as to favor the insertion of the contact member 66 in a forward direction into the bore 70, While strongly resisting the removal of the contact member 66 from the bore 70. The teeth 76 are thus effective to hold the contact member 66 very securely within the bore 70 so that the contact member will not be dislodged or loosened from the plunger 22. To assist in the insertion of the contact member 66 into the bore 70, the wall 74 is formed with a projection 80 which is slidable along a smooth longitudinal surface 81 within the bore 70. The projection 80 is smoothly rounded and generally hermispherical in shape.

The contact blade 68 is struck outwardly from the wall 74 of the contact member 66. The formation of the contact blade 68 results in a slot 82 in the wall 74. It will be seen that the contact blade 68 angles outwardly and rearwardly through a slot 84 which is formed in the plunger 22 and extends radially in an outward direction from the bore 70. The contact blade 68 is smoothly curved and is downwardly convex. It will be seen that the contact blade 68 extends beyond the outside of the plunger 22 for wiping engagement with the flange 36 on the rear leg 32 of the bracket 26. The contact blade 68 engages the rear leg 32 when the plunger 22 is in its initial position, as shown in FIG. 4. The contact blade 68 flexes to an appreciable extent when it engages the rear leg 32, so as to insure the maintenance of good electrical contact between the blade 68 and the leg 32. When the plunger 22 is moved rearwardly against the biasing action of the spring 64, the contact blade 68 moves out of engagement with the leg 32 and springs outwardly, as shown in broken lines in FIG. 4.

The contact blade 68 is connected with the wall 74 at the front end of the slot 82. An ear or tab 86 projects radially from the contact member 66 at the rear end of the slot. It will be seen that the car 86 projects into the slot 84 and acts as a key to orient the contact member with respect to the slot.

As already indicated, the rear leg 32 acts as the fixed contact of the switch and is grounded to the mounting panel 50 through the frame 24. An electrical circuit may be connected to the movable contact member 66 by means of a flexible insulated lead or wire 88. Preferably, the lead 88 is fitted with a terminal 90 which is adapted to be plugged into the rear end of the contact member 66. Thus, the rear end portion of the contact member 66 is formed into a generally cylindrical terminal clip 92 adapted to receive the terminal 90. The clip 92 is formed with a pair of diametrically opposite inwardly extending detent projections 94. It will be seen that the detent projections 94 are smoothly rounded and generally hemispherical in shape. The terminal 90 is generally cylindrical but is formed with a rounded annular groove 96 for receiving the detent projections 94. The terminal 90 has a tapered nose portion 98 which facilitates the insertion of the terminal 90 into the clip 92. The terminal 90 has an enlarged rearwardly disposed portion 100 which is engageable with the rear end of the clip 92 so as to limit the extent to which the terminal may be inserted into the clip. The clip 92 is adapted to hold the terminal 90 securely so that good electrical contact will be assured between the terminal and the clip. It will be understood that the flexible lead 88 may be connected to a lamp circuit or the like and thence to a battery or other source of power.

The switch 20 of FIGS. 1-8 is especially applicable to situations in which it is desired to mount the switch through a hole in a mounting panel. FIGS. 911 illustrate a modified switch which affords a different mounting arrangement. It will be seen that the switch 121) employs the same operating plunger 22 as the switch 20. The spring 64 and the contact member 66 are also the same as previously described and illustrated. However, the frame 24 is replaced with a different frame 124 in the form of a U-shaped bracket having front and

rear legs

126 and 128, extending laterally from a side leg 130. The frame 124 may be made in one piece from heavy sheet metal or other suitable material. The plunger 22 is slidably received in openings 132 and 134 formed in the legs or

members

126 and 128. Thus, the front and

rear legs

126 and 128 constitute front and rear bearing members for the plunger 22. The rear leg 128 also constitutes a fixed electrical contact member, adapted to be engaged by the contact blade 68.

The front member 126 has an inner portion 136 which angles forwardly and laterally from the side leg 130. The front member 126 also has an outer portion 138 which extends outwardly from the inner portion 136 in a direction generally perpendicular to the side leg 130. The outer portion 138 is joined integrally to the inner ortion 136 at a bend 140. Prior to the assembly of the plunger 22 with the frame 120, the entire front member 126 may extend in the direction of the inner portion 136. The bend 140 may be formed during the final assembly of the switch. The rear member 128 extends substantially perpendicular to the side leg 130.

It will be seen that the spring 64 is compressed between the rear bearing member 128 and the shoulder 62 on the plunger 22. The front bearing member 126 acts as a stop for the shoulder 62.

The switch 120 is fitted with a threaded mounting stud 142 which is securely mounted in a hole 144 formed in the side leg 130. The stud 142 may be staked, welded, or otherwise secured to the side leg 130.

The stud 142 is adapted to extend through a mounting hole 146 in a wall or plate 148. A nut 150 may be screwed onto the stud 142 to secure the switch frame 124 to the wall 148.

To prevent the frame 124 from rotating about the stud 142, the side leg 130 is formed with a rearwardly extending arm 1152. The rear end of the arm 152 is turned laterally to form a prong or car 154 which is generally parallel to the stud 14-2. The prong 154 is adapted to be received in a hole 156 in the wall 148. Thus, the prong 154 is effective to locate the frame 124.

The switch 20 of FIGS. l8 is especially well adapted for use as a door switch in automotive service. For such an application, the switch is mounted on the door frame opposite the hinged or inner edge of the door. When the door is closed, the plunger or push button 22 is pushed rearwardly by the door against the biasing action of the spring 64. As a result, the resilient contact blade 68 is moved rearwardly out of engagement with the fixed contact member 32. When the door is opened, the spring 64 returns the plunger 22 in a forward direction. Thus, the contact blade 68 is moved into wiping engagement with the fixed contact member 32. The wiping engagement insures that good electrical contact will be established and maintained. Thus, the switch will give long and highly dependable service. The contact blade 68 may engage any portion of the fixed contact member 32 inasmuch as the blade 68 engages the contact member 32 around the circular opening 34.

The manner in which the movable contact member 66 is mounted within the plunger 22 provides a convenient adjustment of the position of the contact member. Thus, the contact member 66 may be pushed into the bore 70 in the plunger 22 until the desired relationship is achieved between the contact blade 63 and the fixed contact member 32. The saw teeth 76 on the contact member 66 will then securely retain the contact member 66 in its adjusted position.

The construction of the frame 24 is highly advantageous in that the spring fingers 52 on the bracket 26 securely retain the frame within the hole 48 in the mounting panel 50. The form of the bracket 26 is such that it may be made of ordinary cold rolled steel or other relatively soft material, rather than spring stock. Thus, the bracket 26 may be formed very easily and at low cost. The alternative bracket or frame 124 is also very economical.

It will be recognized that either of the illustrated switches may be made expeditiously and at very low cost. Nevertheless, the switches are highly dependable and provide extremely long life. Either switch will make good electrical contact throughout the life of the switch.

Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

I claim:

1. In an electrical switch, the combination comprising a movable operating member of generally cylindrical shape and made of insulating material, a fixed conductive contact member having a generally circular guide opening in which said movable member is slidably received, means supporting said movable member for longitudinal movement relative to said fixed contact member, said movable member having a radial opening therein, a flexible conductive resilient contact blade mounted on said movable member and projecting diagonally out of said radial opening, said blade angling both longitudinally and radially from said radial opening and being movable part way through said opening into Wiping engagement with said fixed contact member at the edge of said opening therein, and means for establishing an electrical connection to said blade whereby an electrical circuit may be connected between said blade and said fixed contact member.

2. In an electrical switch, the combination comprising a movable operating member of generally cylindrical shape and made of insulating material, a frame having front and rear bearing members with generally circular guide openings therein in which said operating member is slidably received, said operating member having an annular shoulder engageable with said front bearing member for limiting forward movement of said operating member, a spring coiled around said operating member and compressed between said shoulder and said rear bearing member for biasing said operating member forwardly, said rear bearing member being made of electrically conductive material and constituting a fixed contact, said operating member being hollow and having a rearwardly opening axial bore therein, a conductive generally channel-shaped movable contact member mounted within said bore, said contact member having a pair of saw-toothed edge portions for digging into said operating member along the inside of said bore whereby said movable contact member is retained within said bore, said saw-toothed edges having teeth which are angled to favor insertion of said movable contact member into said bore while resisting removal of said movable contact member therefrom, said operating member having a slot therein extending outwardly from said bore, said movable contact member having a flexible resilient conductive contact blade angling longitudinally and radially therefrom and projecting outwardly through said slot, said flexible resilient contact blade being movable forwardly part way through said opening in said rear bearing member and into wiping engagement with said rear bearing member around said opening therein, said contact blade being moved out of engagement with said rear operating member when said operating member is moved rearwardly against the biasing action of said spring, a flexible lead for establishing an electrical connection to said movable contact member whereby an electrical circuit may be connected between said movable contact member and said rear bearing member, a generally cylindrical terminal connected to said lead and having an annular detent groove therein, and a generally cylindrical clip portion formed on the rear end of said movable contact member for disengageably receiving said terminal, said clip portion having an inwardly projecting detent element for reception in said detent groove.

3. The combination of claim 2, in which said frame comprises a U-shaped metal bracket having a pair of longitudinal side legs and a rear leg extending transversely between said side legs, said rear. leg constituting said rear bearing member, said frame having front flange means connected to the front ends of said side legs and constituting said front bearing member, each of said side legs having a spring retaining blade formed therefrom and angling forwardly and outwardly for retaining the frame in a hole in a panel or the like.

4. The combination of claim 2, in which said frame comprises a U-shaped metal bracket having a longtiudinal side leg and front and rear legs projecting laterally there from and constituting said front and rear bearing members, said side leg having mounting means thereon for said frame.

5. In an electrical switch, the combination comprising a movable generally cylindrical operating member, a fixed conductive contact member having a generally circular guide opening in which said movable member is slidably received, means supporting said movable member for longitudinal movement relative to said fixed contact member, a conductive flexible resilient contact blade mounted on said movable member and angling longitudinally and radially therefrom, said flexible resilient contact blade being movable part way through said guide opening into wiping engagement with said fixed contact member at the edge of said opening therein, said movable member having means for insulating said blade from said fixed contact member, and means for establishing an electrical connection to said blade whereby an electrical circuit may be connected between said blade and said fixed contact member.

6. The combination of claim 5 in which said movable member is made of insulating material.

7. In an electrical switch, the combination comprising a movable generally cylindrical operating member made of insulating material, a fixed conductive contact member having a generally circular guide opening in which said movable member is slidably received, means supporting said movable member for longitudinal movement relative to said fixed contact member, said movable member having a bore therein and a radial opening extending outwardly from said bore, a movable conductive contact member mounted in said bore and having a flexible resilient contact blade projecting diagonally out of said radial opening, said blade angling longitudinally and radially from said radial opening and being movable part pay through said guide opening into wiping engagement with said fixed contact member at the edge of said opening therein, and means for establishing an electrical connection to said movable contact member whereby an electrical circuit may be connected between said movable contact member and said fixed contact member.

8. The combination of claim 7, comprising a spring biasing said movable operating member in one longitudinal direction, said movable operating member being movable in the opposite longuitudinal direction against the biasing action of said spring.

9. The combination of claim 7, including a spring biasing said movable operating member in one longitudinal direction to a position in which said contact blade is part way through said guide opening and in engagement with said fixed contact member, said movable operating member being movable in the Opposite longitudinal direction against the biasing action of said spring to disengage said contact blade from said fixed contact member.

10. In an electrical switch, the combination comprising a movable generally cylindrical operating member made of insulating material, a frame having front and rear bearing members with generally circular guide openings therein in which said operating member is slidably received, said operating member having a stop portion engageable with said front bearing member for limiting forward movement of said operating member, a spring connected between said operating member and said frame and biasing said operating member forwardly, said rear bearing member being made of electrically conductive material and constituting a fixed contact, said operating member having an axial bore therein and a slot extending outwardly from said bore, a movable conductive contact member mounted in said bore and having a flexible resilient contact blade angling longitudinally and radially therefrom and projecting outwardly through said slot, said flexible resilient contact blade being movable part way through said guide opening in said rear bearing member and into wiping engagement with said rear bearing member around said opening therein, and means for establishing an electrical connection to said movable contact member whereby an electrical circuit may be connected between said movable contact member and said rear bearing member.

11. The combination of claim 10, in which said frame comprises a U-shaped metal bracket having a pair of 8 longitudinal side legs and a rear leg extending transversely between said side legs, said rear leg constituting said rear bearing member, said frame having front flange means connected to the front ends of said side legs and constituting said front bearing member.

12. The combination of claim 11, in which each of said side legs has a spring finger formed therefrom and angling forwardly and outwardly for retaining said frame in a hole in a panel or the like.

13. The combination of claim 10, in which said frame comprises a U-shaped metal bracket having a longitudinal side leg and front and rear legs projecting laterally therefrom and embodying said front and rear bearing members, said side leg having mounting means thereon.

14. The combination of claim 10, in which said movable contact member is formed with a plurality of saw teeth for digging into said operating member within said bore to retain said contact member within said bore.

15. The combination of claim 10, in which said means for establishing an electrical connection to said movable contact member comprises a flexible lead, a generally cylindrical terminal connected to said lead, and a generally cylindrical clip connected to the rear end of said movable contact member for disengageably receiving said terminal.

16. The combination of claim 15, in which said movable contact member is generally channel-shaped and is formed with saw tooth edges for digging into said movable operating member within said bore, said clip being formed integrally with the rear end portion of said contact member.

17. In an electrical SWitCll'l, the combination comprising a movable elongated operating plunger made of insulating material, a fixed conductive contact member having a guide opening in which said movable plunger is slideably received, said opening corresponding in shape to the crosssectional shape of said plunger, means supporting said movable plunger for longitudinal movement relative to said fixed contact member, a conductive flexible resilient contact blade mounted on said movable plunger and angling longitudinally and radially therefrom, said flexible resilient contact blade being movable part way through said guide opening and int o wiping engagement with said fixed contact member at the edge of said guide opening, and means for establishing an electrical connection to said blade whereby an electrical circuit may be connected between said blade and said fixed contact member.

References Cited by the Examiner UNITED STATES PATENTS 2,886,674 5/1959 Spicer 200159 3,092,703 6/1963 Fraser 200159 3,172,983 3/1965 Zoda 200-159 X ROBERT K. SCI-IAEEER, Primary Examiner.

K. CLAFFY, Examiner.

H. HOHAUSER, Assistant Examiner.