US2942088A - Electric switch - Google Patents

Description

June 21, 1960 J. H. MULLEN ETAL 2,942,088

ELECTRIC SWITCH Filed Aug. '7, 1957 32 I I 4 38 55 n 1, 1" z s it 5 III'IIIIIIIIIII'IIII WITNE$$E$ INVENTORS John H. Mullen 8: W Llgyd W, D1,;

United States Patent ELECTRIC SWITCH John H. Mullen and Lloyd W. Dyer, Beaver, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Aug. 7, 1957, Ser. No. 676,872

2 Claims. (Cl. 200168) This invention relates generally to electric switches and more particularly to switches of the push-button type.

An object of the invention is to provide a push-button switch which is of a dust-tight construction.

Another object of the invention is to provide a pushbutton switch of the snap-acting type.

A further object of the invention is to provide a foot or palm-operated push-button switch which can be actuated by pressure at any point on the head of the button.

1 Still: another object of the invention is to provide for locking a push-button switch in a predetermined position.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of the invention a switch unit of the snap-acting type is mounted in an enclosure having a sheet gasket or diaphragm disposed underneath the cover for the enclosure. The switch is actuated by a push-button having a relatively large head. The shank of the push-button is attached to a lever by means of a screw extending through the diaphragm and an opening in the cover which is larger than the diameter of the shank for the head. The lever is pivotally mounted inside the enclosure, thereby guiding the movement of the push-button to actuate the switch when pressure is applied at any point on the head of the push-button.

For a beter understanding of the nature and objects of the invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view, in plan, of an electric switch embodying the principal features of the invention;

Figure 2 is a view, in section, of the switch;

Figure 3 is a detail view, in section, taken along the line IIIIII in Fig. 2; and

Figure 4 is a detail view, in section, takenalong the line IV-IV in Fig. 1.

Referring to the drawing, and particularly to Figs. 1 and 2, the structure shown therein comprises a metal enclosure 10 which may be of a type used in electrical wiring systems and generally known as a Condulet. The enclosure has a threaded opening 11 in one end thereof for connecting a metal conduit containing wires for connecting to a switch unit 12 mounted inside the enclosure. A cover 13 is removably attached to the enclosure 10 by means of screws 14. A sheet gasket or diaphragm 15 is provided for sealing the joint between the cover 13 and the enclosure 10. As shown, the gasket 15 extends across a circular opening 16 provided in the cover 13. The gasket 15 is preferably composed of a material, such as rubber, which is flexible to permit operation of the switch 12 and resilient to seal the joint between the enclosure and the cover.

The switch unit 12 may be of the type described in Patent 2,748,214, issued May 29, 1956 to R. B. Immel. As described in the aforesaid patent, the switch unit 12 has a snap-acting mechanism disposed inside an insulating casing 17. The mechanism is actuated by an operating member 18 which is slidably disposed in the casing 17.

When the member 18 is depressed, a bridging contact member is actuated with a snap action to open a circuit through one pair of contact members and close a circuit through another pair of contact members.- A return spring is provided for returning the operating member 18 to its uppermost position when pressure is removed from the member. Terminal connectors 19 are provided on the switch unit for connecting the wires which enter through the opening 11 in the enclosure 10. The switch unit'12 is attached to the cover 13 by means of screws 21 which extend through spacing sleeves 22 for spacing the unit 12 a predetermined distance below the gasket 15.

A lever 23 is pivotally mounted on a pin 24 which extends through a bracket 25 attached to the cover 13 by screws 26, as shown more clearly in Fig. 3. The bracket 25 has two spaced arms 27 through which the pin 24' extends. Likewise, the lever 23 has two spaced arms 28 through which the pin 24 extends. A torsion spring 29 is mounted on the pin 24 and has two arms 30 which em gage the lever 23 to bias the lever upwardly away from the operating member 18 of the switch unit 12.

A push-button having a head 31 and a shank 32 is attached to the lever 23 by means of a screw 33 which ex-. tends through the gasket 15 into the shank 32 at the opening 16 in the cover 13. A washer 34 is provided between the gasket 15 and the lower end of the shank 32. As shown, the diameter of the shank 32 is considerably less than the diameter of the opening 16 in the cover 13. As also shown, the diameter of the head 31 is much greater than the diameter of the shank 32. Thus, the shank 32 is freely movable in the opening 16, and when pressure is applied at any point on the head 31 the lever 23 guides the movement of the push-button to cause the head of the screw 33 to depress the operating member 18 of the switch unit 12, thereby actuating the mechanism of the switch unit. When pressure is released from the head 31, the spring 29 returns the push-button to its uppermost position in which the lever 23 engages the bottom side of the gasket 15. As previously explained, the operating member 18 is returned to its uppermost position when pressure is removed from the operating member.

As also previously explained, the gasket 15 seals the joint between the cover 13 and the enclosure 10. The gasket is compressed between the lever 23 and the Washer 34 by the screw 33, thereby sealing the opening through which the screw 33 extends into the shank 32. Therefore, the enclosure is of a dust-tight construction, thereby protecting the switch unit 12 from dirt and other foreign matter.

In order to provide for locking the push button in its uppermost position to prevent operation of the switch unit by unauthorized persons, a latch member 35 is pivotally mounted on top of the cover 13 by means of a rivet 36. As shown in Fig. 4, the rivet 36 has a shoulder 37 which is drawn against the cover 13 to permit the latch member 35 to be freely movable about the rivet.

As shown in Figs. 1 and 2, the shank 32 is under cut at 38. The latch member 35 is notched at 39, thereby permitting the latch 35 to swing about the rivet 36 underneath the shank 32 until the notch 39 engages the portion 41 of the shank 32. In this manner, the push button is retained in its uppermost position. A padlock (not shown) may be inserted in an opening 42 provided in the latch member 35, thereby engaging the edge of the enclosure 10 to prevent the latch member 35 from being released. Accordingly, the switch unit cannot be actuated while the latch member is in its locked position.

From the foregoing description it is apparent that the invention provides a foot or palm-operated push-button switch of a snap-acting type which can be actuated by applying pressure at any point on the enlarged head of the push-button. The present switch is particularly suitable for controlling the operation of punch presses and similar machines, since the switch may be easily operated. Furthermore, the switch mechanism is protected against dust and other foreign matter, thereby making it suitable for industrial applications. The switch is of a relatively sim ple construction, and it may be economically manufactured and installed.

Since numerous changes may be made in the abovedescribed construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In an electric switch, in combination, an outer enclosure having a cover with an opening therein, an enclosed switch unit mounted inside the outer enclosure, a reciprocating operating member for the switch unit, a lever pivoted in the outer enclosure, a push-button having a shank attached to said lever through said opening, a head on the push-button outside the outer enclosure, said head being larger than said shank, said shank being smaller than the opening, said lever guiding the movement of the push-button to actuate the operating member of the switch unit when the head is depressed, spring means biasing the lever and the push-button outwardly from said operating member, and locking means pivotally mounted on the cover for engaging said shank to retain the pushbutton in its outermost position.

2. In an electric switch, in combination, an outer enclosure having a cover with an opening therein, an enclosed switch unit mounted inside the outer enclosure, a reciprocating operating member for the switch unit, a lever pivoted in the outer enclosure, a push-button having a shank attached to said lever through said opening, a head on the push-button outside the outer enclosure, said head being larger than said shank, said shank being smaller than the opening, said lever guiding the movement of the push-button to actuate the operating member of the switch unit when the head is depressed, spring means biasing the lever and the push-button outwardly from said operating member, a latch pivotally mounted on the cover for engaging the shank of the push-button to retain the button in its outermost position, and an opening in said latch for receiving means for locking said latch in engagement with said shank.

References Cited in thefile of this patent UNITED STATES PATENTS 1,789,017 Munthesen' Ian. 13, 1931 2,431,747 Fry Dec. 2, 1947 2,669,616 Frank Feb. 16, 1954 2,777,910 Jordan et al Jan. 15, 1957

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