US2601398A - Electric switch - Google Patents

Description

June 24, 1952 E. N. JACOB] ELECTRIC SWITCH Filed April 7, 1948 Patented June 24, 1952 UNITED STATES PATENT OFF ICE ELECTRIC SWITCH Edward N. Jacobi, Milwaukee, 'Wis,, assignor to Briggs ;& iStratton Corporation, Milwaukce, :Wlis, a corporation of Delaware Application April'l, 1948, SerialNo. 19,529

It is customary to provide a certain amount of contactpressure between the circuit making contacts of any electric switch so that theresistance across the contacts will be kept to a minimum. Such contact pressure is particularly desirable inlock switches designed for-automotive use-since without it the vibration normally attendant upon operation of the vehicle is apt to cause intermittent separation of the contacts with resultant high resistance, poor connections, and arcing across the contacts.

'It is also particularly desirable that switches of the rotary contactor type have a strongly marked, detent action comparable to that of conventional quick break snap switches, the advantages of which are well known. A quick break snap action is a feature of special importance in an automotive ignition lock switch inasmuch as it assures positive switch action, and especially since the driver of a motor car seldom gives much attention to the act of turning the ignition switch on or oft It is, therefore, an object of this invention to provide a rotary contactor type electric switch of the character described with a strongly marked detent action by which snap action of the switch is produced.

Another object of this invention resides in the provision of novel means in a rotary electric switch of the character described for effecting acceleration of contact separation so that turning on of the switch causes a quick breaking of the contacts with a snap action.

Another object of this invention resides .inproviding a rotary switch of the character described with simple detent mechanism requiring a definite effort on the part of an operator actuating the switch to move the same between its on and off" positions and which operates to accelerate contactor motion between the on and off positions of the switch so as to produce a highly desirable snap action of the switch.

Still another object of this invention is to provide a rotary switch with simple detent mechanism and employing metal stampinss that can be easily and inexpensively manufactured.

One other object of this invention resides in the provision of a switch of the character described wherein the switch mechanism may be sub-assembled and inserted into the case as a unit.

With the above and other objects in view.v which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the app nded claim, it bein understood that such changes in the precise embodiment "of the hereindisclosed invention may be made as come within the scope of the claim.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of theprinciples thereof, and in which:

Figure 1 is a side elevation-of an ignition lock switch of the type used in automobiles and the like with portions of the switch case and internal mechanism broken away and shown in section to illustrate the application of this invention thereto;

Figure 2 is a cross sectional view taken through the switch case along the plane of line 22 of Figure '1;

Figure 3 is an exploded perspective view showing the component parts of the switch mechanism; and

Figure 4 is a diagrammatic view of the driver carried cam track.

Referring now particularly to the accompanying drawing in which like numerals indicate like parts, the numeral 1 designates generally a lock switch of the type designed for mounting on the instrument panel of an automobile for the control of the ignition circuit of the automobile.

The switch here shown comprises a casing 2 bored to rota-tably receive an actuator A in the front portion of the case adjacent to the panel upon which the switch is mounted. In

, a lock switch of the type here shown a key operated rotatable pin or plate tumbler cylinder constitutes the actuator for the switch.

The casing 2 is enlarged at its rear end and a counterbore 2' in the enlarged rear portion of the casing accommodates the switch mechanism. The switch mechanism includes a terminal plate 3 'formed from non-conductive material and disposed crosswise of the counterbore to close the rear of the casing.

The terminal plate is secured to the casing in a position closing the mouth of the counterbore by means of the more or less conventional practice of spinning the side wall of the case at the rear thereof over the back face of the terminal plate to clamp it against an annular ledge on the inner wall of the case a slight distance inwardly of the mouth of the counterbore.

A plurality of stationary contacts 4 are carried by the terminal plate and are exposed at the inner face thereof to be substantially flush therewith. Terminal studs 4 electrically connected with the stationary contacts 4 and extending from the rear of the insulating terminal plate provide for the attachment of electrical conductors to the switch.

The rotatable contactor of the switch is in the form of a spider stamped from thin sheet brass and has a plurality of circumferentially spaced rearwardly extending legs 5 each terminating in a foot I constituting the movable contacts per se and adapted for engagement with the stationary contacts 4 on the inner face of the terminal plate.

The contactor has its feet I normally engaged with the inner face of the terminal plate and is adapted to be rotated thereacross to establish or break the circuit or circuits controlled by the switch.

The contractor 5 is operatively connected with an insulating disc 8 through which rotation may be imparted to the contactor. The connection between the contactor and insulating disc coinprises three circumferentially spaced legs 9 on the contact spider remote from the contacts 1 thereof and which extend longitudinally forwardly to engage in mating apertures ID in the insulating disc. The legs 9 are joined to the body of the spider by shoulders 9' normal to the legs 9 and all lying in the same plane engageable with the rear face of the insulating disc 8 and the outer ends of the legs 9 projecting through the aperture ID are rolled over against the forward face of the disc to rigidly non-rotatably secure the contactor to the disc.

Attention is directed to the fact that the disc 8 is made from a circular blank of insulating material having a diameter to loosely fit the bore 2' and thus the disc holds the contactor centered in the bore and assures proper engagement between the contact feet I and the stationi cry contacts 4 on the terminal head. The disc is preferably slabbed off at three equispaced areas to minimize friction between its edges and the wall of the bore 2'.

The insulating disc 8 is in turn carried by a driver or coupling element designated generally by the numeral I I. The driver comprises a substantially disc-shaped body l2 rotatable in the oounterbore 2 between the disc and the bottom of the counterbore.

A suitable central non-circular hole 13 is provided in the body [2 to receive a similarly shaped driving lug hi on the inner extremity of the actuator or look cylinder A so that the driver or coupling element H is constrained to rotate with the lock cylinder when the latter is turned by means of a proper key 15 while being free to slide axially relative to the actuator and the insulating disc and contactor joined thereto.

A plurality of circumferentially spaced legs IS, in the present case three, extend rearwardly from the body l2 of the driver H and provide for drivingly connecting the coupling element with the contactor. The legs l6 have a rectangular shaped cross section and are equally spaced from the axis of the driver to be received in notches i"! cut into the arcuate peripheries of the insulating disc 8. Such engagement of the legs in the notches I? provides a splined driving connection between the driver and the disc and consequently the contactor, by which the insulating disc is constrained to rotate with the driver while the latter is slidable axially in the case relative to the disc.

A compression spring [8 confined between the body l2 of the driver and the insulating disc 8 yieldingly urges the disc and contactor rearwardly toward the terminal plate, and urges the driver forwardly toward the front of the casing.

Laterally projecting shoulders (9 formed on the rear extremities of the driver legs I5 prevent the insulator disc 8 from becoming detached from the driver by the separating force of the spring and enable the driver and the connected disc and contactor to be installed in the counterbore as a sub-assembly. Establishment of the driving connection between the driver and disc, of course, requires the disc to be tilted for assembly with the driver.

The spring l8 as stated, yieldingly urges the driver forwardly toward the bottom of the counterbore 2 and such motion of the driver is limited by three circumferentially spaced cam rollers 20 positioned in the bottom of the counterbore so as to be fixed with respect to the case. The rollers 20 are rotatably mounted on shafts 2| having their axes radial to the switch case, the shafts being received in wells 2 1 formed in the bottom of the case.

The body of the driver is formed with a cam surface 22 on its front face and this cam surface is maintained in engagement with the peripheries of the cam rollers 20 by the compression spring 18 so that the cam surface determines the axial position of the driver in the switch case. It will also be noted that the thrust of the spring I8 is borne by the rollers and consequently the easing, and that the spider 5 holds the insulating disc 8 at all times spaced inwardly of the shoulders I9 on the driving legs 16 so that the full force of the spring is utilized to press the contactor against the inner face of the terminal plate.

Prior to assembly of the switch mechanism in the switch case one end of the spring is first placed about the inturned walls defining the noncircular hole l3 in the body of the driver. The insulator 8 is then set in place over the spring by tilting the insulator and advancing two of its driving notches ll down under the shoulders 19 and against the inner sides of the driver legs 16 against the pressure of the spring I8 until the remaining notch may clear the shoulder I!) on the third leg [6 whereupon the disc is again tilted to bring its remaining slot ll under its retaining shoulder [9.

The shoulders N then prevent the insulator 8 from being expelled from the legs 16 by the spring (8 and hold the disc connected with the driver for assembly in the case as a unit.

The cam rollers 20 are slipped onto the shafts 2i and placed in the wells 2| in the bottom of the counterbore 2', and the driver, together with the spring and the insulator and spider, assembled as aforesaid, is inserted into the counterbore 2, with the cam rollers 20 engaging the cam track 22, and the actuator lug l4 received in the hole [3 in the driver body l2. The terminal plate 3 is then secured in place closing the mouth of the counterbore.

When the switch is in the oif" position the rollers are seated in depressions 25 in the cam surface 22 on the driver as indicated in Figure 1 and diagrammatically in full lines in Figure 4. In this position, the depressions 25 define the off position of the switch, and the contact feet 1 of the spider bear comparatively lightly against the inner face 3 of the terminal plate 3, but are not in contact with any of the stationary contacts 4. This condition is brought about by the action of the spring I8 as hereinbefore pointed out.

As the actuator or switch key is turned toward the switch on position, the depressions 25 are carried out of alignment with the rollers and humps E.) on the cam track are brought onto the rollers. There is one hump for each of the rollers, and these humps cam the driver rearwardly toward the terminal plate and cause the Spring 18 to be compressed between the driver and the insulator disc 8, thereby increasing the pressure of the contact feet 1 against the face 3' of the contact plate.

Just before the contact feet 1 are brought into complete engagement with the stationary contacts A, the humps 25 move over their rollers 2t and other depressions 21 at the opposite sides of the humps are brought into alignment with the rollers. The depressions 2'1 define the on position of the switch. In the on position of the switch, contact pressure is greater than in the off position. This increased pressure is brought about by the axial position of the driver, the on depressions 25 being deeper than the on depressions 2'1.

-In the on position of the switch defined by engagement of the rollers in the depressions 2! the contact feet '1 of the contactor 5 are completely engaged with the stationary contacts 4. Continued rotation of the contactor at this time is prevented by engagement of a lug 28 on the case projecting rearwardly from the bottom of the counterbore with one end of an arcuate slot 29 in the body 12 of the driver.

When the switch is turned either toward its on or on positions, a definite effort is required to rotate the lock cylinder or other actuator and overcome the force which the spring 18 exerts to hold the cam rollers 22 in the detent forming depressions 25 and 21 of the cam track and to carry the humps 26 from one side of the rollers to the other. Immediately after the peaks of the humps 26 pass the axes of the rollers and before the contacts are completely disengaged or engaged, the spring I8 cooperates with the rollers and cam track to accelerate rotation of the driver to the on or off position by reason of the inclination of the opposite sides of the humps to produce an extremely rapid make and break minimizing arcing of the contacts.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent that this invention provides a simple and inexpensive yet highly efficient mechanism for a lock switch or other type rotary switch which produces a highly desirable snap action of the switch to insure rapid and positive making and breaking of the circuit or circuits controlled by the switch.

What I claim as my invention is:

In a switch of the type having a bored case: a terminal plate fixed at the rear of the case with its front surface transverse to the axis of the case bore and having a plurality of stationary terminals exposed on said front surface; a plurality of rotatable rollers each supported on a shaft received in slot-like wells in a part of the case spaced forwardly of the terminal plate, said wells opening rearwardly and forming partial bearings disposing the rollers with their axes substantially radial to the axis of the bore, each roller being received in a rearwardly opening cavity in the case; a movable contactor in the case intermediate the terminal plate and said rollers, said contactor being rotatable on an axis transverse to the terminal plate and having contacts adapted to be carried into and out of circuit-making engagement with the terminals on the terminal plate in consequence of its rotation; a cam surface rotatable in the bore of the case between the contactor and said rollers, coaxially with the contactor, and adapted to operatively engage said rollers and to be moved axially toward and from the terminal plate in consequence of rotation; a spline-d connection between the cam surface and the contactor; and a compression spring reacting between the contactor and the cam surface to bias the same axially in opposite directions to thus urge the contactor into firm engagement with the terminal head and urge the cam surface into engagement with the rollers to preclude forward displacement of the rollers out of said wells and to enable the rollers to cooperate with the cam surface to move the same forwardly in consequence of its rotation to thus increase spring pressure on the contactor as it is rotated toward the position in which its contacts are carried into circuit making engagement with the terminals.

EDWARD N. JACOBI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,715,014 Soreng May 25, 1929 1,746,887 Douglas Feb. 11, 1930 1,884,148 Norriel et al. Oct. 25, 1932 2,441,808 Fry May 18, 1948

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