US3914563A

US3914563A - Key operated switch

Info

Publication number: US3914563A
Application number: US484305A
Authority: US
Inventors: James C Prior
Original assignee: Sola Basic Industries Inc
Current assignee: Sola Basic Industries Inc
Priority date: 1974-06-28
Filing date: 1974-06-28
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

A tamper-proof electric switch having a key receiving rockable switch actuator in a housing, the housing means having a key receiving slot and the actuator being related thereto so as to close off access to the interior of the switch.

Description

United States Patent Prior Oct. 21, 1975 KEY OPERATED SWITCH James C. Prior, Gardena, Calif.

Sola Basic Industries, Inc., Milwaukee, Wis.

Filed: June 28, 1974 Appl. No.: 484,305

Inventor:

Assignee:

US. Cl. 200/42 T Int. Cl. H0111 27/00 Field of Search 200/42 T, 42 R, 44

References Cited UNITED STATES PATENTS 9/1931 Millermaster et al, 200/42 T 4 .LE .3 3 VIII! '11 '1'! Primary Examiner-Herman Hohauser Attorney, Agent, or FirmSmythe & Moore [57] ABSTRACT A tamper-proof electric switch having a key receiving rockable switch actuator in a housing, the housing means having a key receiving slot and the actuator being related thereto so as to close off access to the interior of the switch.

4 Claims, 7 Drawing Figures U.S. Patent 0m. 21, 1975 3,914,563

FIG.1 TH

6 5 F l l 4 I l KEY OPERATED SWITCH This invention relates to electric switches, and more particularly, to a tamper-proof key operated switch.

It is desirable in electric switches to provide for key operation so that only authorized persons with a key therefor can operate the same. Such switches need to be simple in construction and to be tamper-proof. Prior switches, such as shown in US. Pat. Nos. 1,825,325; 1,929,311 and 3,497,646, have not been completely satisfactory because it has been possible to use pieces of wire or articles to reach the switch mechanism by inserting the same through the key opening or around the operator to operate the same. Also, a person using such a piece of wire or article can receive an electrical shock as a result thereof.

One of the objects of the invention is to provide an improved tamper-proof key operated switch.

In one aspect of the invention, a switch can be enclosed in the usual insulating housing having a slot therein. Any number of poles can be used and can be of the toggle or snap acting type. An oscillatable or rockable saddle or switch mechanism, actuator or operator is located within said housing and between the housing slot and the switch mechanism, the saddle being trunnioned in the housing and completely straddling the slot so as to prevent access from the outside to the switch mechanism by extraneous or unauthorized devices.

These and other objects, features and advantages of the invention will become apparent from the following description and drawings which are merely exemplary.

In the drawings:

FIG. 1 is a sectional view of a two pole switch showing the switch in a central position with both poles open;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view similar to FIG. 1 but showing one of the poles of the switch in closed position and the other one open;

FIG. 4 is an enlarged side view of one form of key;

FIG. 5 is an end view of the key of FIG. 4;

FIG. 6 is an enlarged fragmentary view of the key as it is being inserted into the slot; and

FIG. 7 is a fragmentary end view looking in the direction of line 7-7 of FIG. 3.

The invention will be described in conjunction with a double pole a.c. switch having a central position with both poles open. Other kinds of similar switches can have the invention applied thereto.

The same reference numerals will be used in the various figures for the same parts where appropriate.

The switch housing 10 can be composed of insulating material parts ll, 12 with a closure member 13 having a slot therein. There is an arcuate shaped slot 15 for receiving switch actuator 16. Switch actuator 16 has trunnion 17 carried in the walls of housing members 1 l, 12. The switch actuator includes

cams

18, 19 which are on either side of the arcuately shaped central portion 20, the arcuately shaped seat 15 of the closure member 13 being complimental to the arcuate surface 20 of central portion 16 of the switch actuator 16.

Resilient switch blades

21, 22 are on either side of the actuator 16, the

blades carrying contacts

23, 24 which coact with their respective terminal contacts 25,

25A (FIG. 7). Cam 18 operates blade or resilient arm 21 and cam 19 operates blade or resilient arm 22.

One end of spring 26 is carried by projection 27 of housing 11 and the other end is held by projection 28 on actuator 16.

In the central position illustrated in FIG. 1, both switches are open,

cams

18, 19 holding their respective blades downwardly.

When key 29 is inserted through slot 14 into aperture 30 in switch actuator 16, and moved counterclockwise (FIG. 3), cam 18 will move upwardly or rotate to permit resilient blade arm 21 to close contact 23 onto contact 25. At the same time, cam 19 will press downwardly on blade arm 22 so as to keep its contacts open.

Spring 26 will move to the position shown in FIG. 3 and maintain one set of contacts open and the other closed. By moving the key clockwise (FIG. 3), the other set of contacts will be closed. Arms 31, 32 on the actuator 16 cooperate with

resilient posts

33, 34 to limit movement of the switch actuator. Thus, it can be seen from the foregoing that the close fit of the arcuate seats of the actuator 16 and closure 13 together with the narrow slot 14 will prevent the insertion of wires or other bodies around the switch actuator.

It should be apparent that various details of construction can be made without departing from the spirit of the invention except as defined in the appended claims.

What is claimed is:

1. In a key operated electric switch, the combination including switch mechanism movable to at least two switching positions, a housing for said switch mechanism and enclosing the same, an upstanding closure member arranged in said housing and having an elongated slot therein, and a rockable switch mechanism actuator means between said slot and said switch mechanism, the underside of said slot being arcuate and the top of said rockable switch mechanism having an arcuate shaped portion complemental to said arcuate slot, said switch mechanism operator having vertically extending key receiving closed bottom aperture means, said switch mechanism operator completely straddling said slot in all positions and blocking access to the switch mechanism in said housing, and a key means insertable within said closure slot and having projection means on one end thereof for insertion within said key receiving aperture means to permit arcuate switch actuating movement of said switch mechanism actuator means by said key means and otherwise blocking access to the switch mechanism.

2. In a key operated electric switch as claimed in claim 1 wherein the switch mechanism is a snap action switch.

3. In a key operated electric switch as claimed in claim 1 wherein said switch mechanism actuator comprises a sector-shaped body having closed bottom key receiving apertures and having shafts extending therefrom, said shafts being rockably receivable in the housing and having cams thereon for operating the switch mechanism.

4. A key operated electric switch as claimed in claim 3 wherein said switch mechanism actuator means includes a projection for receiving a spring between the projection and interior of the housing, said spring being of sufficient length to cause snap action operation of the switch mechanism as the switch mechanism actuator is rocked.

Claims

1. In a key operated electric switch, the combination including switch mechanism movable to at least two switching positions, a housing for said switch mechanism and enclosing the same, an upstanding closure member arranged in said housing and having an elongated slot therein, and a rockable switch mechanism actuator means between said slot and said switch mechanism, the underside of said slot being arcuate and the top of said rockable switch mechanism having an arcuate shaped portion complemental to said arcuate slot, said switch mechanism operator having vertically extending key receiving apertures therein with closed bottoms, said switch mechanism operator completely straddling said slot in all positions and blocking access to the switch mechanism in said housing, and a key means insertable within said closure slot and having projections on one end thereof for insertion within said key receiving apertures to permit arcuate switch actuating movement of said switch mechanism actuator means by said key means and otherwise blocking access to the switch mechanism.

3. In a key operated electric switch as claimed in claim 1 wherein said switch mechanism actuator comprises a sector-shaped body having closed bottom key receiving apertures and having shafts extending therefrom, said shafts being rockable receivable in the housing and having cams thereon for operating the switch mechanism.

4. A key operated electric switch as claimed in claim 3 wherein said switch mechanism actuator means including a projection for receiving a spring between the projection and interior of the housing, said spring being of sufficient length to cause snap action operation of the switch mechanism as the switch mechanism actuator is rocked.