US3054879A

US3054879A - Pushbutton switch

Info

Publication number: US3054879A
Application number: US3602A
Authority: US
Inventors: John E Soreng
Original assignee: Indak Manufacturing Corp
Current assignee: Indak Manufacturing Corp
Priority date: 1960-01-20
Filing date: 1960-01-20
Publication date: 1962-09-18
Anticipated expiration: 1979-09-18

Description

P 1962 J. E. SORENG 3,054,879

PUSHBUTTON SWITCH Filed Jan. 20, 1960 INVENTOR.

John E 50119225 United States Patent Ofilice 3,054,879 Patented Sept. 18, 1962 This invention relates to pushbutton switches, which have a variety of applications. Thus, such switches may be employed in various control circuits, such as the starter circuit for an internal combustion engine.

One object of the present invention is to provide a pushbutton switch which is extremely dependable in operation, yet is easy to manufacture and low in cost.

A further object is to provide a new and improved pushbutton switch in which the movable contact element automatically aligns itself with the stationary contact element, so as to assure good electrical contact therebetween.

Another object is to provide a new and improved pushbutton switch which is arranged so that there is a wiping action between the movable contact and the fixed contacts, so that the contacts are automatically kept free from dirt or other deposits which might impair the effectiveness of the electrical contact between the contact elements.

A further object is to provide a pushbutton switch in which the movable contact member is freely rotatable, so that it will tend to present fresh contact areas to the stationary contacts as the switch is used repeatedly.

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 pushbutton switch to be described as an illustrative embodiment of the present invention, the View being drawn to show the manner in which the switch may be mounted on a panel by means of a mounting plate, the panel and the mounting plate being shown in section.

FIGS. 2 and 3 are rear and front elevational views, respectively, of the pushbutton switch itself.

FIG. 4 is an enlarged sectional View, taken generally along a line 44 in FIG. 3.

FIGS. 5 and 6 are cross-sectional views, taken generally along lines 5-5 and 66 in FIG. 4.

It will be seen that the drawings illustrate a pushbutton switch 10 which comprises a plurality of stationary contact points 12, adapted to be bridged or connected together by a movable contactor 14. As shown, the stationary contact points 12 are mounted on a supporting member or plate 16 which is made of insulating material. It will be seen that the plate 16 is in the form of a circular disk. The contacts 12 may comprise the head portions of rivets 18 which extend through spaced holes 20 in the insulating plate 16. Terminals 22 in the form of angular lugs may be secured to the rear side of the insulating plate 16 by the rivets 18. Thus, each terminal lug 22 has one flange 24 which lies flat against the plate 16 and is mounted on the rear portion of the rivet 18, and another flange 26 which projects rearwardly, at right angles to the plate 16. It will be seen that the contact members 12 are substantially conical in shape. They project forwardly from the plate 16 for engagement by the movable contactor 14.

It will be seen that the contactor 14 is mounted on a movable supporting member in the form of a flexible boot 2%. The front portion of the boot 28 is formed into a pushbutton 30 which may be engaged and pushed rearwardly by one finger or the thumb of the user. Annular grooves 31 are formed into the front of the pushbutton 30 to provide a non-slip surface.

The boot 23 has a bellows portion 32 which supports the pushbutton portion 30 so that it may readily be pushed inwardly toward the fixed contacts 12. As shown, the bellows portion 32 comprises a generally cylindrical wall 34 which is somewhat larger in diameter than the pushbutton portion 30. The cylindrical wall 34 is connected to the pushbutton portion 30 by an annular flange 36 which is generally L-shaped in cross-section. Thus, the flange 36 has a pair of angularly

related legs

38 and 40. As shown, the leg 38 extends inwardly .in a generally radial direction from the cylindrical wall 34, and then joins with the leg 40, which extends to the edge portion of the pushbutton 30, in a direction generally parallel to the cylindrical axis of the wall 34. The leg 38 of the flange 36 actually angles rearwardly to some extent, so as to impart great flexibility to the boot 28.

The boot 28 is preferably made of rubber, or some other rubber-like material which is flexible, resilient and relatively soft. The resilience of the boot 28 restores it to its original shape when the pushbutton 30 is released. Thus, the boot 28 provides its own spring action.

In this case, the boot 28 is formed with an enlarged annular flange 42 which retains the supporting plate 16. As shown, the flange 42 is generally 'C-shaped in crosssection. Thus, the flange 42 has three legs 44, 46 and 48. The leg 44 extends outwardly from the rear end of the cylindrical wall 34, and then joins with the leg 46 which is generally cylindrical and thus extends generally parallel to the axis of the supporting disk 16, along the outer edge thereof. The leg 48 extends inwardly along the rear surface of the disk 16. Thus, the C- shaped flange 46 forms an internal annular groove 50 which is adapted to receive the edge portion of the insulating disk 16. By flexing the C-shaped flange 42, the disk 16 may readily be inserted into the groove 50 or removed therefrom.

In the illustrated construction, the movable contactor 14 comprises a dished metal member which has a skirt portion 52 angling outwardly from a flat central disk portion 54. The contactor 14 is mounted on the rubber boot 28 by means of a rivet 56 having a front head portion 58 which is retained in a generally T-shaped recess 60 formed in the pushbutton portion 30 of the rubber boot 28. The rivet 56 has a reduced portion 62 which extends loosely through an opening 64 in the central disk-shaped portion 54 of the contactor 14. At its extreme rear end, the rivet 56 has a head 66 which retains the contactor 14 on the rivet. Because of the loose fit between the reduced portion 62 and the opening 64, the contactor 14 is free to rotate on the rivet. Moreover, the contactor 14 is free to swing or rock to a substantial extent on the rear portion of the rivet.

It will be seen that the skirt 52 of the contactor 14 is frusto-conical in shape and is of sufficient size to be received over the stationary contact points 12. Thus, the contact points 12 are adapted to be engaged by the inner surface of the frusto-conical skirt 52, at diametrically opposite points. The angle of inclination or taper of the frusto-conical skirt 52 corresponds generally to the angle at which the conical contact points 12 taper. Accordingly, the inside of the frusto-conical skirt is adapted to engage each of the conical contact points 12 along a definite line of contact.

From FIG. 1 it will be seen that the switch 10 is adapted to be mounted against a panel or wall 70, by means of a clamping or mounting plate 72. In this case, the panel 7 (l is formed with an opening 74, through which the terminals 22 project in a rearward direction. The mounting plate 72 is secured to the panel 70 by means of a pair of bolts or other fasteners 76.

As shown, the cylindrical portion 34 of the rubber spacers boot 28 projects forwardly through an opening '78 in the mounting plate 72. A forwardly projecting annular flange 80 is formed on the mounting plate '72 around the opening 78. It will be seen that the flange all is generally L-shaped in cross-section. Thus, the flange 80 has a cylindrical portion 82 which projects forwardly from the mounting plate 72. In addition, the flange 80 has an inwardly projecting radial portion 84- connected to the front end of the cylindrical portion 82. The radial flange portion 84 engages the front of the enlarged rear portion 42 of the boot 28 and is adapted to clamp the enlarged rear portion against the panel 79. Thus, the inwardly projecting flange portion 48 of the boot 28 is firmly held against the panel '70 around the opening 74. The cylindrical portion 82 of the flange St! extends around the rear cylindrical portion 46 of the boot 2%.

Normally, the contactor 14 is spaced forwardly from the fixed contact points 12, as shown in full lines in PEG. 4. The switch it) is operated by pushing the pushbutton member 30 rearwardly with the thumb or one finger of the operators hand. This brings the inside of the frusto-conical contactor 14- into contact with the outer surfaces of the contact points 12, as shown in broken lines in FIG. 4. There is a definite wiping action between the contacting surfaces, when the pushbutton switch is operated due to the self-aligning movement of the contacting surfaces. This wiping action keeps the contacting surfaces clean and obviates any possibility of faulty electrical contact due to the accumulation of dirt or other deposits on the contacting surfaces. The frusto-conical shape of the contactor 14 causes it to align itself automatically with the conical contours of the contact points 12. Aligning movement of the contactor 14 is readily possible, because of the loose connection between the contactor and the supporting rivet 56. Inasmuch as the contactor '14 is freely rotatable on the rivet, the contactor will tend to rotate to various positions due to normal use of the switch and normal conditions of vibration under which the switch is used. Thus, the contactor 14 will constantly be presenting new contact surfaces to t e stationary contact points 12. Accordingly, the high efliciency of the pushbutton switch is maintained over an extremely long life span. Of course, the rubber boot 23 excludes dust and other foreign material from the coutacting surfaces. At the same time, the rubber boot provides a spring action which disengages the contactor 14 from the contact points 12 when the pushbutton member 30 is released.

Various 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. A pushbutton switch, comprising, in combination, a generally circular insulating plate having a pair of generally conical contact points mounted thereon and projecting forwardly from said plate, a pair of terminals connected to said contact points and mounted on the rear side of said plate, a hollow flexible boot made of rubberlike material and extending from the front side of said plate, said boot having a pushbutton portion disposed centrally on said rubber boot and at the front end thereof, a mounting stud mounted in the rear side of said pushbutton member and extending rearwardly therefrom inside said boot, and a movable sheet metal contactor loosely mounted on said mounting stud and freely rotatable and swingable thereon, said contactor being generally frusto-conical and being receivable over said generally conical contact points to establish an electrical circuit therebetween, said contactor tapering at an angle corresponding to the angle of taper of said contact points to afford wiping contact between said contact points and said contactor, said contactor being self-aligning with said contact points and being rotatable to present new contacting surfaces to said contact points.

2. In a. switch, the combination comprising an insulating plate, a plurality of generally conical contacts projecting forwardly from said plate, a hollow flexible resilient boot connected to the front of said plate, and a thin metal contactor mounted on the inside of said boot and movable rearwardly into engagement with said contacts to establish an electrical circuit therebetween, said boot biasing said contactor forwardly away from said contacts, said boot having means on the inside thereof supporting said contactor for free rotation and loose swinging movement relative thereto so that said contactor will be self-aligning with said contacts, said contactor having an inner frusto-conical wall flaring toward said contacts and engageable therewith with a wiping action.

3. In a switch, the combination comprising a substantially circular insulating plate, a pair of spaced rivets mounted in said plate and having heads on the front side thereof in the form of generally conical contact points projecting forwardly from said plate, a pair of terminals mounted on said rivets and extending from the rear side of said plate, a hollow generally cup-shaped boot mounted on said plate and extending forwardly therefrom, said boot being of flexible resilient rubberlike material, said boot having a front centrally disposed pushbutton portion, a stud mounted in said pushbutton portion and projecting rearwardly therefrom into the interior of said boot, a sheet metal contactor having an opening therein loosely mounted on said stud, said contactor being freely rotatable and rockable relative to said stud, said contactor being movable rearwardly against said contact points to establish an electrical circuit therebetween, said boot normally biasing said contactor forwardly out of engagement with said contact points, said contactor having a flaring skirt-like wall with a generally frusto-conical inner surface engageable with said contact points with a wiping action, the flaring angle of said contactor wall corresponding generally with the conical angle of said contact points, said contact points being engageable with said wall at diametrically opposite locations thereon.

4. A pushbutton switch, comprising, in combination, an insulating plate having a pair of generally conical contact points mounted thereon and projecting forwardly from said plate, a pair of terminals connected to said contact points and mounted on the rear side of said plate, a hollow flexible boot made of rubber-like material and extending from the front side of said plate, said boot having a pushbutton portion disposed centrally on said rubber boot and at the front end thereof, a mounting stud mounted in the rear side of said pushbutton member and extending rearwardly therefrom inside said boot, and a movable sheet metal contactor mounted on said mounting stud, said contactor being generally frustoconical and being receivable over said generally conical contact points to establish an electrical circuit therebetween, said contractor tapering at an angle corresponding to the angle of taper of said contact points to afford wiping contact between said contact points and the inside of said contactor.

References Cited in the file of this patent UNITED STATES PATENTS 1,717,057 Meuer June 11, 1929 2,409,483 Gandelot Oct. 15, 1946 2,444,552 Brantingson July 6, 1948