US3541280A

US3541280A - Slide switch with rocker contact

Info

Publication number: US3541280A
Application number: US764873A
Authority: US
Inventors: Guy M Farrell
Original assignee: Chicago Switch Inc
Current assignee: Chicago Switch Inc
Priority date: 1968-10-03
Filing date: 1968-10-03
Publication date: 1970-11-17
Anticipated expiration: 1987-11-17

Description

.Nov. 17, 1970 a. M. FARRELL SLIDE SWITCH WITH ROCKER CONTACT Filed 001:. 3, 1968 R 66 B G. 4-

6 INVENTOP I IMF? ll I I z afiys United States Patent 3,541,280 SLIDE SWITCH WITH ROCKER CONTACT Guy M. Farrell, Elmhnrst, Ill., assignor to Chicago Switch, Inc., Chicago, 11]., a corporation of Illinois Filed Oct. 3, 1968, Ser. No. 764,873 Int. Cl. H01h 13/28 U.S. Cl. ZOO-67 13 Claims ABSTRACT OF THE DISCLOSURE A switch construction including a base with at least one pair of spaced apart contacts mounted on the base. A movable contact in the form of a rocking element is adapted to engage the spaced apart contacts and to force itself between these contacts. Each of the spaced-apart contacts is provided with an inclined edge so that the rocker element will wipe against the respective edges in the course of its movement between the contacts. An overcenter spring is preferably employed for imparting driving movement to the rocker element. The push button employed in the construction includes camming means which will engage the rocker element in the event that the spring is inefiective to impart the necessary movement to the rocker element. A detent spring is associated with the push button and registers with the switch housing in a position of rest so that suificient force for insuring rapid switching must be applied.

This invention relates to a switch construction which provides certain unique characteristics from the standpoint of fast switching action and reliable operation. In addition, the switch is designed so that manufacturing materials and procedures are not unduly complicated or expensive.

Extreme requirements for switch operation exist in a will be damaged or will lose their operating capabilities.

Proper switch operation for more sophisticated circuits also involves extremely rapid operation so that arcing can be virtually eliminated. Even minor changes in resistance which can occur if switch contacts are made or broken on a gradual basis are not tolerable in many circuits.

Switches which are characterized by rapid and reliable operation are described in copending application Ser. No. 638,877, filed May 16, 1967. The switches described in this application involve the use of spring means which are designed to provide very rapid operation and to eliminate the possibility of teasing a switch or allowing contamination of contacts. Thus, the switches include overcenter spring means or equivalent drive features so that the switch contacts will only be made or broken when a specific amount of force is applied to the actuating means and wherein a wiping action is involved in the contacting process so that the build-up of contaminating materials can be virtually eliminated.

It is a general object of this invention to provide switch constructions which are characterized by highly reliable and efficient operation.

It is a more specific object of this invention to provide switch constructions of the type referred to in the aforementioned copending application but which have additional characteristics which provide improved contact pressure and wiping action which provide automatic means for breaking of contacts in the event of welding of contacts which provide means for insuring high speed operation, and which can be manufactured in a relatively simple fashion.

These and other objects of this invention will appear hereinafter, and for purposes of illustration, but not of limitation, a specific embodiment of the invention is shown in the accompanying drawing in which:

FIG. 1 is a perspective view of a switch construction characterized by the features of this invention;

FIG. 2 is a longitudinal sectional view of the switch construction taken about the line 22 of FIG. 5;

FIG. 3 is a vertical sectional view taken about the line 33 of FIG. 2;

FIG. 4 is a vertical sectional view taken about the line 44 of FIG. 2;

FIG. 5 is a horizontal sectional view taken about the line 5-5 of FIG. 2;

FIG. 6 is a reduced longitudinal sectional view illustrating a detent mechanism employed in the construction; and

FIG. 7 is a side elevational view of an alternative form of spring means for the construction.

The switch construction of this invention generally comprises a base portion having at least one pair of spaced-apart contacts and a movable contact member adapted to be interposed between the spaced-apart contacts. One improvement of the invention involves the provision of inclined edges on the spaced-apart contacts which are engaged by the movable contact so that the movable contact imparts a camming action as it is forced between the spaced-apart contacts during the switch operation. This arrangement provides a desirable wiping action while also providing almost instantaneous pressure contact to insure good electrical performance.

The construction includes a rocker element which can be employed for making and breaking switches at either end, depending upon the position of a push button which engages the rocker element. The push button is provided with a camming surface which will engage the rocker element during switch operation to insure proper movement of the rocker element in response to the push button movement. This camming means is especially effective when contacts become welded so that spring means or the like which are normally employed for operating the rocker element will not impart sufficient force to move the rocker element in response to the push button movement.

The switch construction also employs detent means which engage when the push button is at a designated position of rest. When the switch is to be actuated for making or breaking of contacts, the force applied to the push button must be sufficient to overcome the pressure applied by the detent means. With this arrangement, a relatively great amount of force is required to get the push button moving, and this insures rapid movement and reliable operation of the spring means so that teasing is not possible.

The switch construction also includes overcenter spring means located between the push button and rocket element. This overcenter spring means is asociated with a spring mounted holder whereby a combined spring action is provided between the push buttom and the rocker element. As will be explained, this combined action permits much greater flexibility in the selection of suitable overcenter spring means thereby providing savings in production costs.

The drawings illustrate a switch construction 10* which combines the improvements referred to. The construction includes a base portion 12 having terminal elements 14 extending outwardly therefrom. An outer housing 16 interfits with the base portion to provide a cover for the construction.

The housing 16 includes a rectangular slot 18 which receives the outwardly extending push button 20. The push button 20 includes laterally extending sections 22 which ride on upstanding walls 24 formed integrally with the base 12.

The push button 20 includes a hollow interior which receives a cup-shaped holder 26 and asociated coil Spring 28. A groove 30 is defined in the bottom of the holder, and an overcenter spring 32 has one end received in this opening. The other end of the spring terminates in a V- shaped groove 34 which is received in a saddle 36 defined by rocker element 38.

The rocker element 38 is supported on a pivot pin 40, this pivot pin being received in opposed openings 42 defined in the base 12. The rocker element preferably comprises a conductive material and the opposite ends 44 of this element comprise contact engaging portions.

Pairs of movable contacts in the form of

blades

46 and 48 are secured to the base 12. The terminals 14 comprise integral extensions of these contacts, and these terminals also serve to hold one end of each contact in a stationary position relative to the base.

The opposite ends of the

contacts

46 and 48 are freely movable; however, these contacts are spring biased so that their ends 54 normally press respectively against

abutments

50 and 52 which are molded integrally with the base 12. This normal position of the contact ends is shown at the right-hand side of FIG. 5.

In the opreation of the switch construction, the rocker element 38 is adapted to assume the position shown in FIG. 2 or the opposite position which would locate the end 44 in the lower position. The contact ends 54 are engaged by the rocker ends in the closed position of the switch and the adjacent upstanding edge of the

contacts

46 and 48 also engage the sides of the rocker.

When the push button 20 is shifted laterally from the position shown in FIG. 2, the action of the overcenter spring 32 will cause the rocker to move. As noted in the aforementioned copending application, the use of an overcenter spring initially results in the application of a force teding to retain the rocker in the same position. When a particular point in the movement of the push button has been reached, the overcenter action will take place resulting in rapid movement of the rocker element to the opposite position.

Where the spring holder 26 and spring 28 are employed, the initial movement of the push button will cause the holder 26 to move upwardly within the confines of the push button. It has been found that this combination of springs eliminates the need for providing a great deal of flexibility in the overcenter spring. Thus, this spring can be manufactured from stiffer material since the yielding ability of the spring 28 will hold down the force required to move the push button. The lateral and vertical dis tances between the pivot points defined by the groove 30 and saddle 36 can also be reduced with this arrangement.

When the contact element 44 is shifted in the manner described, the contact will initially engage

inclined edges

56 and 58 defined by the

contacts

46 and 48, respectively. A wiping and camming action will then occur as the contact 44 is forced between the

contacts

46 and 48. These contacts will then assume the position shown in FIG. 5, that is, a position out of contact with the

abutments

50 and 52. When the contact end 44 is moved between the

contacts

46 and 48, the spring bias applied to the later contacts will provide ideal pressure engagement.

It will be noted that the extensions 22 of the push button 20 define inclined bottom surfaces 60. These surfaces cooperate with the inclined surfaces 62 defined by the contact ends 44 of the rocker element. Thus, the inclined ends 60 will engage the surfaces 62 during sliding movement of the push button in the event that the surfaces 62 have not been moved out of the way by the action of the overcenter spring. This arrangement is primarily useful in the event that welding of contacts has occurred. The operator can be assured that breaking of contacts will take place when the push button is moved.

When mounting the push button in the assembly, a pair of spring members 64 are located on either side of the push button. The ends of these springs engage shoulders 66 defined by the legs 22 so that the springs are mounted in the bowed condition shown in FIG. 6. A detent 68 is formed at the center of each spring, and this detent cooperates with the small openings 70 defined in the switch enclosure 16. One of these openings is located so that a detent will be received in an opening at each of the switch positions.

The detent arrangement is primarily useful during initial movement of the push button. Thus, the operator of the switch must apply pressure sufficient to dislodge the detent, and this will insure that the operator applies sufficient pressure to move the push button at a relatively high speed. This arrangement is highly valuable in the event that the overcenter spring 32 should be somewhat unreliable in its ability to always maintain the switch in one or the other of the extreme positions. In addition, the use of the detent spring reduces the possibility of acidental switching, for example if the operator should brush against the push button.

It will be noted that in the construction described, the ends 44 of the rocker element provide a break before make arrangement. Thus, as shown in FIG. 2, the end 44 in the raised position, will not engage the right-

hand contact elements

46 and 48 until the other end of the rocker element disengages the left-

hand contacts

46 and 48. It will be appreciated, however, that the rocker element can be readily redesigned so that the switch will be make before break.

FIG. 7 illustrates an alternative form of the invention wherein a pair of springs are interposed between the saddle 36 defined by the rocker element 38 and the groove 30 defined by the holder 26. This arrangement provides even greater versatility in the selection of the material for forming the springs 80 since the desired spring action can be obtained with widely varying characteristics.

Where either a spring 32 or a combination of springs 80 are employed, the coil spring 28 can be eliminated. Where this arrangement is employed; however, the spring characteristics of the fiat springs must be more carefully selected so that the over-center action can be achieved.

It will be understood that various changes and modifications may be made in the switch construction described which provide the characteristics of this invention without departing from the spirit thereof, particularly as defined in the following claims.

That which is claimed is:

1. In a switch construction including a base, at least one pair of spaced-apart contacts, and a movable contact members adapted to be interposed between said spaced apart contacts, the improvement wherein said spacedapart contacts comprise elongated spring members having movable end portions for engagement by said contact member, said end portions being normally spaced apart a distance less than the thickness of said contact member, an inclined edge defined by each end portion whereby said movable contact first engages said inclined edges when the movable contact is moved toward the spaced-apart contacts, and wherein said movable contact member wipes along said edges as the movable contact is forced between said spaced-apart contacts.

2. A construction in accordance with claim 1 wherein said movable contact is conductive and thereby makes contact between said spaced-apart contacts.

3. A construction in accordance with claim 1 wherein said movable contact comprises a rocker element, and a push button operatively connected to said rocker element for imparting pivotal movement thereto.

4. A construction in accordance with claim 3 wherein said rocker element includes contact engaging portions at either end, and including separate pairs of said spacedapart contacts for engagement by the respective ends of said rocker element, said rocker element alternately making and breaking the separate pairs of spaced-apart contacts.

5. A construction in accordance with claim 3 wherein said push button assumes at least two positions of rest during operation of the switch, and including means associated with said push button for registering with means associated with said construction in said positions of rest whereby the force necessary for actuating the switch includes the force needed to move said associated means out of registry.

6. A construction in accordance with claim 5 wherein the means associated with said push button comprises a spring member having a protruding portion, and wherein the means associated with said construction comprises openings in a wall of the construction, said spring member moving adjacent said wall with said protruding portion being received in one of said openings at each position of rest.

7. A construction in accordance with claim 3 including over center spring means interposed between said push button and said rocker element, said spring means operat ing to rapidly move said rocker element when said push button is moved to the extent that the resistance of said spring means in one direction is overcome whereby the spring means will move the rocker element in the opposite direction.

8. A construction in accordance with claim 7 wherein said spring means comprise a,first spring associated with said push button, the axis of said first spring being perpendicular to the direction of movement of said push button, and a second spring comprising a strip of metal having a curvilinear cross section, one end of said strip engaging the rocker element, and the other end of said strip engaging the underside of a holder for supporting said first spring.

9. A construction in accordance with claim 3 wherein said rocker element defines a camming surface at the end opposite its contact end, and including camming means associated with said push button for engagement with said camming surface or driving said rocker element out of contact with said spaced apart contacts.

10. A construction in accordance Wtih claim 9 including spring means associated with said push button for moving said rocker element when said push button has moved beyond a predetermined position during operation of the switch, and wherein said camming action only occurs if said spring means is ineffective to cause movement of said rocker element.

11. A construction in accordance with claim 1 wherein said spaced-apart contacts comprise elongated metal strips, the end portions defining said inclined edges being freely movable relative to said base, and wherein the opposite ends of said strips include integrally formed terminal elements extending through said base.

12. A construction in accordance with claim 11 wherein said strips are spring biased toward each other, and including abutment means defined by said base, said free end portions of said strips normally pressing against said abutments, and wherein movement of said movable contact into engagement with said free end portions moves the end portions out of contact with said abutments.

13. A construction in accordance with claim 7 wherein said overcenter spring means comprise a pair of flat springs defining outwardly turned central portions, said central portions being located in opposed facing relationship relative to each other whereby each of the fiat springs provides over-center action during operation of the switch.

References Cited UNITED STATES PATENTS 2/1951 Wood. 10/ 1969 Farrell et a1 200-76 US. Cl. X.R. 200-46, 164, 166