US3510613A - Snap action switch and combination switch and variable resistance control - Google Patents

Description

May 5, 1970 w. A. BARDEN ETAL 3,510,613

. V SNAP ACTION SWITCH AND COMBINATION SWITCH AND VARIABLE RESISTANCE CONTROL Filed July 10. 1967 INVENTORS WAYNE A. BARDEN 4 MERVEN B. glsmm BY yfi hl/ 4 ATTOQNEY United States Patent SNAP ACTION SWITCH AND COMBINATION SWITCH AND VARIABLE RESISTANCE CONTROL Wayne A. Barden and Mervin B. Arisman, Elkhart, Ind.,

assignors to CTS Corporation, Elkhart, Ind., 21 corporation of Indiana Filed July 10, 1967, Ser. No. 652,327 Int. Cl. H01h 13/26 US. Cl. 200-67 2 Claims ABSTRACT OF THE DISCLOSURE A switch having a lost motion connection between a contactor driver and a floating contactor permits rotation of the floating contactor relative to the contactor driver and promotes a self-cleaning action of the floating contactor as well as proper alignment of the floating contactor relative to a pair of fixed terminal means when biased thereagainst by spring means. The floating contactor is loosely retained in an oversized cavity in the contactor driver and spring means provide a biasing force for urging the floating contactor into good electrical contact with the terminal means. An abutment wall carried by the contactor driver strikes the floating contactor and acts as a bearing surface for driving the floating contactor away from the terminal means against the action of the spring means when the switch is snapped from a closed switch condition to an open switch condition. In one embodiment the switch is combined with a variable resistance control.

BACKGROUND OF THE INVENTION The present invention relates to electrical components and, more particularly, to a combination variable resistance and electrical switch control and to an electric switch.

Electrical components of the type that include a switch and a different discrete electrical device are often used in electronic equipment such as radio and television receivers. Frequently the electrical component includes a variable resistance control combined with a snap action switch in a single housing. The switch may have one of several different configurations. For example, the switch may be of the type commonly referred to as single-pole single-throw, single-pole double-throw, or double-pole double-throw, to name but a few.

In the design and manufacture of electrical components including a snap action switch, one of the problems encountered relates to the electrical current carrying capacity of the switching elements, sometimes referredto as the current rating of the switch. It will be appreciated that the problem of increasing the current rating is made more difiicult by size limitations of the switch since the switch normally occupies only a fraction of the already small volume of the electrical component. This size limitation becomes increasingly severe with double-throw and double-pole switches since such switches require a larger number of current carrying elements than single-pole single-throw switches.

One factor that has an influence on the current rating of a given electric switch is the manner in which the movable contactors make and break electrical contact with fixed terminals within the switch. It is generally desirable that a movable contactor move with a positive action into properly aligned engagement with a pair of fixed terminals in order to diminish bouncing of the movable contactor against the fixed terminals and to reduce the opportunity for arcing between the movable contactor and fixed terminals.

3,510,613 Patented May 5, 1970 In addition to having a suflicient current rating it is important that the switch be reliable, i.e., have a normally expected life of from 25,000 to 50,000 actuation cycles. The rate at which the movable contactors and fixed terminals undergo surface deterioration is one of the factors that at least partially determines the life of the switch. It can be demonstrated that as the interface of the movable contactor and fixed terminals becomes pitted, burned, and generally irregular the heating effect of the electric current flowing across the interface will increase. This heating phenomena can eventually foreshorten the life of the switch by destroying the temper in springs used in snap action swtches and, in some cases, cause increased burning and pitting of the surfaces of the movable contactor and fixed terminals. It is, therefore, desirable that the contact surfaces in the switch be maintained in good condition and that provision be made for quickly and cleanly moving the movable contactor away from the fixed terminals so as to diminish the opportunity for arcing.

Accordingly, it is an object of the present invention to provide a new and improved electrical component having the various desirable features set forth above. A general object of the present invention is to provide an improved variable resistance control in combination with a snap action switch that is characterized by improved current carrying characteristics. Another object of the invention is to provide an improved electrical switch operable with a snap action, reliable in operation, and exhibiting improved current carrying characteristics. A more specific object of the present invention is to provide an improved electrical component wherein movable contactors are loosely retained by a contactor driver so that a cleaning action of the contact surfaces and positive alignment of the movable contactors is accomplished. Yet another object of the present invention is to provide an improved electrical control characterized by a relatively simple and compact construction wherein a movable contactor is quickly and cleanly moved away from the fixed terminals.

SUMMARY OF THE INVENTION In accordance with one form of the invention, we have provided an electrical control with a snap action switch in which a lost motion connection is provided between the contractor driver and one or more movable contactors so that the movable contactors may float relative to the contactor driver. The movable contactors are loosely retained for rotation relative to the contactor driver and fixed terminal means and thus the points of contact along the interfaces of the floating contactors and fixed terminal means can change during successive actuations of the switch and aid in preventing premature failure of the switch. The floating contactors are loosely retained in an oversized seat provided by a cavity in the contactor driver and, when the contactor driver is actuated to a closed switch position, spring means positively bias the floating contactors into electrical contact with a pair of electrical terminal means to insure good alignment and electrical contact between the floating contactors and the terminal means. The spring means also aid in diminishing bouncing of the floating contactors on the fixed terminals when the floating contactors are moved with a snap action against the terminal means. The lost motion connection between the contactor driver and floating contactors provides a quick and clean break between the floating contactors and fixed terminals when the switch is snapped to an open switch condition. With the lost motion connection, the contactor driver moves a short distance before engaging the floating contactors with an impacting action to move the contactors away from the fixed terminals. Abutment walls formed integral with the contactor driver define one extremity of the cavities and provide a bearing surface for positively engaging and moving the floating contactors away from the fixed terminal means.

Although the spring means which effect the switch snap action can bias at least one movable contactor toward the terminal means, in the preferred embodiment, the spring means comprises a pair of leaf springs which are particularly adapted for positively biasing a pair of movable contactors toward the fixed terminal means.

In one of the preferred embodiments of the invention, the snap action switch is combined with a variable resistance control in a housing provided with two apertured end walls. A control means rotatably supported in the housing makes wiping contact with a resistance element disposed in the housing and a cam driver integral with the control means is engageable with the cam surface of a switch actuator which drives a toggle spring off center to provide a snap action of the contactor driver between first and second stable positions.

BRIEF DESCRIPTION OF THE DRAWING The subject matter which we regard as our invention is set forth in the appended claims. The invention itself, however, together with further objects and advantages thereof may be better understood by referring to the following description taken in conjunction with the accompanying drawings in which: FIG. 1 is a perspective view of a combination variable resistance control and electrical switch adapted for mounting to a panel; FIG. 2 is a sectional view taken along lines 11-11 in FIG. 1; FIG. 3 is an exploded perspective of the electrical switch portion of the control shown in FIG. 1; FIG. 4 is an enlarged detailed view of a portion of a contacfor driver; FIG. 5 is a view taken along lines V-X in FIG. 2 assuming that FIG. 2 is shown in full and shows the relationship of a pair of floating contactors to fixed terminal means during an open switch condition; and FIG. 6 is a view similar to FIG. 5, showing the relationship of the floating contactors and fixed terminal means during a closed switch condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings, an electrical component embodying one form of the invention is generally identified by the reference numeral 11. As shown in FIG. 1, the electrical component comprises a variable resistance control 12 and a switch 13. A control means 14, molded from suitable insulating material, includes a control shaft 16 supported by the front insulating base or plate 17 and intermediate wall 18 which may be formed integrally with the housing 12. The control shaft 16 has a rotor 19 formed integrally therewith carrying a wiper 21 for making contact with an arcuate resistance path 22. The resistance path 22, e.g., a carbon film resistance element, is suitably bonded or mechanically secured to the front plate 17 and the ends of the resistance path are suitably connected to a pair of not-shown terminals. When a wirewound resistance element is employed instead of a carbon film resistance element, it is insulatedly disposed in the housing in a manner well known in the art.

A collector ring 23 held in fixed concentric relationship with respect to the resistance path 22 is provided with a not-shown center terminal. The wiper 21 electrically connects the resistance path 22 to the collector ring 23. One of the means for mounting the electrical component 11 to a not-shown mounting panel comprises a ground plate 24 provided with a locating pin 25 and an extruded externally threaded bushing 26 rotatably supporting the control shaft 16. After the threaded bushing 26 has been inserted through a mounting panel, a not-shown lock washer and nut are used to lock the component into place on the panel. In order to support the control means 14 and contactor driver 27, the intermediate wall 18, forming the rear of the variable resistance control 13, is provided with a pair of pivot post supporting apertures 28 and 29. The intermediate wall 18 is also provided with a cutout 31 through which cam surfaces 32a and 32b of the switch actuator 32 project in an interference path with the cam driver 33 forming part of the control means 14.

As best shown in FIG. 3, the switch 13 comprises a generally cup-shaped housing 34 having a base 36 closing one end thereof and means for connecting the housing 34 to the variable resistance control 12 such as the ears 37 adapted to project through slots formed in the intermediate wall 18. The base 36 is substantially flat and may be formed integrally with or separate from the housing 37. When the base 36 is formed as a separate element it is provided with a notch 36a cooperating with boss 34a to achieve the desired orientation of the base 36 relative to the housing 34. In order to support the fixed terminals 37-40 a plurality of apertures are formed in the base 36 through which the solder lugs 37a-40a are inserted. The base 36 is also provided with an aperture 41 supporting the contactor driver pivot post 27a. As can be seen in FIGS. 2 and 3, toggle spring 42 and actuator 32 are assembled on the pivot post 27b of the contactor driver 27. When assembled, the ends 42a and 42b of the spring are positioned in the aperture 320 and spring retainer 270 to maintain compression of the toggle spring 42. It will be understood that contactor driver 27 is driven between stable open and closed switch positions by the action of the switch actuator 27 in moving the toggle spring 42 off center when the cam driver 33 engages the cam surfaces 32a or 32b and rotates the switch actuator about the pivot pin 27b. The edges 27:: and 27d are arranged to engage the internal walls of the housing and, when a floating contactor is not arranged to limit the movement of the contactor driver in one direction, both edges are useful in defining the stable position of the driver 27.

Now having reference to FIG. 3 and 4 it will be seen that the contactor driver 27 is provided with two cavities 43, 44 providing oversized seats for loosely retaining a pair of floating contactors 46, 47 having portions 46a and 47a of reduced size. The smaller portions 46a, 47a of the floating contactors are formed with a predetermined diameter less than the diameter of the cavities 43, 44 to provide a lost motion driving connection as will be hereinafter more fully explained. Although we have illustrated the floating contactors 46, 47 as solid cylindrical elements with reduced diameter portions, it will be understood that the contactors could be formed with a substantially uniform diameter throughout, provided the cavities 43, 44 were made proportionately larger. It will be further understood that the contactors could have an elliptical or ovoidal cros-sectional configuration and be hollow or ring-shaped rather than solid elements.

When the switch 13 is assembled, the pivot posts 27a, 27b of the contactor driver 27 are supported in the aperture 41 in the base 36 and the aperture 29 in the intermediate wall 18. The floating contactors 46, 47 are loosely seated in the cavities 43, 44 and positioned in generally triangular areas defined by the fixed terminals 37-40 and leaf springs 48, 49 (best shown in FIGS. 5 and 6).

Although we have shown in the exemplification a pair of leaf springs 48, 49 supported in cantilever fashion between the pins or bosses 45 and 50, it will be understood that one or both of the springs could be mounted on the contactor driver 27. It should be further understood that the action of the toggle spring 42 in holding the contactor driver 27 in a closed switch position can be utilized to hold one of the floating contactors 46 or 47 in electrical engagement with the fixed terminal means in lieu of one of the leaf springs 48 or 49. In actual practice, we have found it preferable to use two leaf springs 48 and 49 in order to insure substantially identical operating characteristics of the two poles of the switch, each switch comprising a floating contactor and a pair of fixed terminal means. When the switch is snapped to a closed position, the leaf springs resiliently urge each floating contactor into a self-aligned position with hte fixed terminal means and help prevent contactor bouncing against the fixed terminal means.

The cavities 43, 44 have been illustrated as generally circular. However, it is only necessary that the con tactor driver be formed with abutment walls in order to provide bearing surfaces which will abut and move the floating contactors 46 and 47 away from the fixed terminal means against the bias of the spring means. In FIGS. and 6, the phantom lines 51 and 52 represent walls generally normal to the surface of the contactor driver 27 and these walls define the cavities 44 and 43 respectively.

During the closed switch condition illustrated in FIG. 6, the abutment wall portions 51a, 52a of the cavity defining walls 51, 52 are spaced from the driven portion of the floating contactors during the closed switch condition. When the switch is snapped to an open condition, the abutment walls move a distance predetermined by the relative dimensions of the floating contactors 46, 47 and contactor driver before abutting the floating contactors. Thus a lost motion driving connection is provided to insure a fast and clean opening of the switch. The lost motion coupling arrangement permits rotation of the floating contactors as the switch is actuated and this in turn contributes to a self-cleaning action of the floating contactors.

When the switch is in the open position of FIG. 5, the abutment walls 51a, 52a present a bearing surface against the leading edge of the floating contactors 46, 47 and hold the floating contactors 46, 47 against the bias of the leaf springs 48, 49 away from the terminals 37-40. As the contactor driver is snapped to the closed switch position, the leaf springs 48, 49 urge the floating contactors into initial contact with portions 37a and 39a of the terminals 37 and 39. This initial contact position is shown by phantom lines 46' and 47 in FIG. 5. When the floating contactors are moved into a final closed switch position by the leaf springs 48, 49 a cleaning action is provided as the floating contactors tend to roll along the terminals 37 and 39. In the closed switch position of FIG. 6, the bearing surfaces 51a, 52a are spaced at predetermined distance from the leading edge of the floating contactors as explained hereinbefore.

When the contactor driver 27 is snapped from a closed switch position to an open switch position, the contactor driver 27 moves an amount corresponding to the predetermined distance before striking the floating contactors. The impacting action aids in quickly breaking the floating contactors away from the fixed terminal contacts. Thereafter the contactor driver drives the floating contactors away from the fixed terminal contacts against the bias of the leaf springs 48, 49. The floating contactors, driven by the biasing surfaces 51a, 52a, tend to roll outwardly along the leaf springs 48, 49 and thus insure that a different segment of the contact surfaces will engage the terminal means on the next actuation of the switch.

From the foregoing description of an electrical component embodying our invention, it will be seen that we have provided an improved electrical control including a switch characterized by simplicity and positive action. The switch is capable of carrying as much as six amperes of current without adversely aflfecting the anticipated life of the switch. Since the floating contactors rotate and present a different point of contact with each successive actuation of the switch, a relatively clean contact interface is maintained to insure further satisfactory operation and life of the switch.

Although we have shown a switch comprising a separate housing and a substantially flat separate base, it will be appreciated that the switch housing and base can be integrally molded of suitable material to form a unitary structure. It will also be understood that the various applications of the electrical control described herein are intended as illustrative embodiments of the invention and that the invention is not limited to such embodiments thereof. It is to be understood, therefore, that we intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the present invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A snap action two-position electrical switch comprising a housing open at one end and having a base, at least four electrical terminal means supported on the base, a plurality of floating contactors movable into and out of electrical contact with predetermined pairs of said electrical terminal means, a contactor driver held in spaced relation to the base and supported for pivotal movement relative thereto, said contactor driver having a plurality of bearing surfaces formed integrally therewith and defining at least one extremity of a plurality of apertures formed in the contactor driver, a first leaf spring urging one of the floating contactors to an extremity of one of the apertures, and a second leaf spring urging the other of the floating contactors to an extremity of another of the apertures, said leaf springs applying a force to each of the contactors and biasing the floating contactors into electrical contact With selected ones of the terminal means when the switch is in the closed position, said apertures providing oversized seats for the floating contactors and cooperating with the bearing surfaces to provide a lost motion connection between the contactor driver and floating contactors whereby the bearing surfaces will move predetermined distances before abutting the floating contactors as the switch is snapped from a closed switch condition to an open switch condition, an actuator, and a toggle spring connecting the actuator to the driver, said actuator moving the contactor driver back and forth between first and second positions corresponding to open and closed switch conditions, said floating contactors being held away from the respective pairs of terminal means by the bearing surfaces in the first position and resiliently urged against the terminal means by the spring means in the second position, each of said bearing surfaces being spaced predetermined distances from the corresponding floating contactors in the second position.

2. The switch of claim 1, wherein the contactor driver is molded from an electrically insulating material, and the floating contactors have a generally circular cross-section.

References Cited UNITED STATES PATENTS 2,524,784- 10/ 1950 Franks et al. 2,820,864 1/ 1958 Newman et al. 3,015,706 1/ 1962 Fichter.

ROBERT K. SCHAFFER, Primary Examiner D. SMITH, JR., Assistant Examiner US. Cl. X.R.

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