Quick-acting, Safety Disconnect Electrical Switch

Abstract

A quick-acting electrical switch which provides a positive means for disconnecting relatively high currents in a single conductor. Circuit connection is made between two switch contacts by a reciprocally movable, spring-loaded bridging assembly. When the bridging assembly is pushed into the "Current ON" position, it is locked in position by a trigger-actuated latching mechanism. The bridging assembly will snap to the "Current OFF" position when the trigger is actuated either mechanically or by means of a solenoid. In the preferred embodiment, the latch mechanism engaging portion of the bridging assembly is free to rotate with respect to the latching mechanism to provide wear equalization. A plurality of the quick-acting switches can be stacked together with a common trigger for multiple pole requirements.

Description

This invention relates to electrical switches in general, and more particularly to a quick-acting, positive-disconnect electrical switch.

It is often desirable, especially in the case of electrically driven vehicles such as, industrial forklift trucks and golf carts, to have a means for quickly and positively disconnecting a load from a high-current source. Various devices have been employed in the past including pullout plugs and high-current conventional switches with or without a "deadman" feature. Preferably, the disconnecting means should provide for manual circuit-closing with a positive latching of the movable switch member in the closed circuit position and manual or electrically actuated release of the latching mechanism coupled with a positive and rapid interruption of the electrical circuit.

It is accordingly a general object of the present invention to provide a quick-acting switch for positively disconnecting at least one conductor.

It is another object of the invention to provide a quick-acting, positive-disconnect switch with a latching mechanism which holds the switch in the closed circuit position until the latching mechanism is unlatched by actuation of a trigger.

It is still another object of the invention to provide a quick-acting, positive-disconnect electrical switch which can be released from the closed circuit position either manually or electrically.

It is a further object of the invention to provide a latching mechanism which provides for wear equalization of the latch-engaging portion of the movable switch member.

It is a feature of the present invention that the positive-disconnect, quick-acting switch can be fabricated from readily available materials including convention, off-the-shelf components.

These objects and other objects and features of the present invention will best be understood from a detailed description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings, in which:

FIG. 1 is a view in side elevation of the quick-acting, positive-disconnect switch of the present invention with a portion of the cover broken away;

FIG. 2 is a plan view of the switch shown in FIG. 1 with the cover removed;

FIG. 3 is a plan view of the switch with the upper section of the housing removed;

FIG. 4 is a view in side elevation and partial section showing the relationship of the rotatable latching shaft and reciprocally movable bridging assembly shaft;

FIG. 5 is a view taken along line A--A in FIG. 4 showing the latching shaft in the closed circuit position;

FIG. 6 is another view taken along line A--A in FIG. 4 showing the position of the latching shaft at the moment of release; and

FIG. 7 is still another view taken along line A--A in FIG. 4 showing the latching shaft in the open circuit position.

Turning now to the drawings, there is shown in FIGS. 1 through 3 thereof, a quick-acting positive-disconnect electrical switch constructed in accordance with the present invention and indicated generally by the reference numeral 10. The various components of the switch 10 are contained within a molded, electrically insulating housing indicated generally by the reference numeral 12. The housing 12 is divided into two sections, an upper section 14 and a lower section 16. Looking at FIG. 3, two electrical connectors 18 and 20 are mounted within cavities formed in the lower housing section 16. Corresponding cavities are also formed in the upper housing section 14 to accommodate the portions of the switch components which extend above the upper surface of the lower housing section 16.

Circuit connection between the two electrical connectors 18 and 20 is accomplished by means of a reciprocally movable bridging assembly indicated generally by the reference numeral 22, as best seen in FIG. 3. The bridging assembly 22 includes an electrically conductive bridging member 24 which is shown in the closed circuit position in FIG. 3. The bridging assembly itself, is spring-loaded by means of compression spring 26 in the open circuit position. In order to maintain the bridging assembly in the closed circuit position as shown in FIG. 3 a latching mechanism 28 is provided in the quick-acting, positive-disconnect switch 10. The latching mechanism engages the reciprocally movable bridging assembly in the closed circuit position as will be described in detail hereinafter. When the latching mechanism 28 is unlatched by a trigger unit, indicated generally by the reference numeral 30 in FIG. 2, the entire bridging assembly 22 is moved to the left, as viewed in FIG. 3, by the spring biasing provided by compression spring 26.

The electrical connectors 18 and 20 are connected to an outside circuit by means of wires 32. Each connector has a convex contact portion 34 which engages the bridging member 24 in the closed circuit position. The electrical connectors 18 and 20 are urged toward each other by T-shaped springs 36. The specific structure of the electrical connectors 18 and 20 and their associated biasing springs 36 is shown in detail in U.S. Pat. No. 3,091,746, issued to Edward D. Winkler on May 28, 1963, for ELECTRICAL CONNECTOR. In the open circuit position, the housing structure in the lower housing section 16 limits the extent to which the contact portions 34 move toward each other in order to maintain electrical separation. When the bridging assembly 22 is pushed to the right, as shown in FIG. 3, the bridging member 24 engages and spreads apart the electrical connector contact portions 34. This provides a wiping action of the electrically contacting surfaces which removes any oxidation buildup on the surfaces.

Turning now to the detailed structure of the bridging assembly 22 and looking at FIG. 3, the bridging assembly 22 comprises the previously mentioned bridging member 24 and a bridging shaft 38 which is rotatably mounted within a T-shaped connecting block 40. The bridging shaft 38 has a reduced diameter portion 42 which fits within a corresponding bore in the connecting block 40. Two connecting pins 44 are fitted through the block 40 in position to engage a further reduced diameter portion of the bridging shaft. The bridging member 24 is in turn secured to the T-shaped block 40 by means of a pin 46. Given this configuration, it can be seen that the bridging shaft 38 is free to rotate about its own axis without moving the bridging member 24. The rotation of the bridging shaft 38 is used to provide wear equalization on latch engaging surface 48 of the bridging shaft 38.

Preferably the connecting block 40 is formed from an electrically insulating material so that the bridging shaft 38 can be fabricated from an electrically conducting material, such as, hardened steel. However, it should be understood that both the connecting block and bridging shaft can be constructed from electrically insulating materials without sacrificing the rotational wear equalization feature.

Looking now at FIGS. 3 through 7, the bridging shaft 38 is provided with another reduced diameter portion 48 which has a right-angle shoulder 50 at one end and a tapered or sloping shoulder 52 at the other end. The reduced portion 48 and shoulder 50 cooperate with the latching mechanism 28 as described below to hold the bridging assembly in the closed circuit position when the bridging assembly is pushed in by means of knob 54. In the closed circuit position, the bridging assembly 22 is latched in position with the release spring 26 in compression between knob 54 and housing shoulder 56.

With the upper housing section in place as shown in FIG. 1, the various components of the switch are held in position by securing the upper and lower housing sections 14 and 16, respectively, by means of suitable fasteners representationally indicated by the reference numeral 58. The split housing configuration facilitates component replacement, if necessary. However, other structural arrangements can be employed to house the components of the quick-acting switch 10.

The specific latching mechanism used in the quick-acting, positive-disconnect switch 10 can best be understood by referring to the drawings, with particular reference to FIGS. 4 through 7. A latching shaft 60 is rotatably mounted in the housing 12, as shown in FIGS. 1 through 3, with its longitudinal axis transverse at a right angle to the axis of the bridging shaft 38. The latching shaft 60 has a transverse groove 62 which forms a flat surface 63 having two interior shoulders 64 and two exterior edges 66 as shown in FIGS. 4 through 7. Rotation of the latching shaft 60 is accomplished by means of a longitudinal member or crossbar 68 which is secured at right angles to the longitudinal axis of the latching shaft by means of pin 70. A tension spring 72 is connected between one end of the crossbar 68 and housing wall 74. This arrangement biases the latching shaft 60 in a counterclockwise direction. Looking at FIG. 5, which represents the closed circuit position, the right-hand exterior edge 66 of the latching shaft is held against the reduced diameter portion 48 and the right-angle shoulder 50 of the bridging shaft 38. Since the spring biasing of the bridging shaft 38 by means of spring 26 is to the left, as viewed in FIG. 5, the bridging assembly will remain in the closed circuit position as long as the latching shaft 60 engages the right-angle shoulder 50.

It has already been mentioned that the release of the latching mechanism 28 is accomplished by actuating a trigger mechanism 30. Looking at FIG. 2, the manually actuated trigger mechanism 30 comprises a plunger 76 which is spring-loaded in the off position by spring 78. When the plunger 76 is depressed or pushed to the right as viewed in FIG. 2, it forces the crossbar 68 in a direction opposite to the direction of force exerted by the latching shaft biasing spring 72. In other words, the latching shaft 60 is rotated in a clockwise direction. Referring back again to FIGS. 5 through 7, when the latching shaft 60 is rotated to the point where the flat surface 63 is parallel to the axis of the bridging shaft 38, as shown in FIG. 6, the latching mechanism becomes unlatched and the bridging assembly will be forced to the left by the expansion of the compressed spring 26. FIG. 7 illustrates the open circuit relationship of the bridging shaft 38 and the latching shaft 60. The latching mechanism 28 and trigger plunger are protected from environmental conditions by a suitable cover 80.

It will be appreciated from the preceding description that the quick-acting, positive-disconnect switch 10 allows the user to initially energize a circuit by pushing in on the knob 54 until the latching mechanism 28 engages the bridging assembly 22 in the closed circuit position. Subsequent release and disconnection of the circuit is accomplished by depressing the manually actuated plunger 76. In some circumstances, it is desirable to have either electrical actuation of the trigger mechanism or a combination of both manual and electrical actuation. In the preferred embodiment of the present invention this can be accomplished easily by mounting an electrically actuated solenoid 82 on the upper housing section 14 with the solenoid's plunger 84 mechanically connected to the crossbar 68. With this arrangement the quick-acting, positive-disconnect switch 10 can be used to disconnect a load from a high-current source in response to a number of predetermined parameters. For instance, conventional voltage or current-sensing equipment can be used to generate an electrical signal to actuate the solenoid 82 in response to an under- or over-voltage or current condition.

Claims

Having described in detail a preferred embodiment of our invention, what we desire to secure by Letters Patent of the United States is:

1. A quick-disconnect electrical switch comprising:

a. an electrically insulating housing;

b. first and second electrical connectors each having a contact portion, said connectors being mounted in spaced relation within said housing with the contact portions thereof facing each other;

c. spring means mounted within said housing for urging said electrical connectors toward each other for a limited distance while maintaining electrical separation between said contact portions; d. a reciprocally movable bridging assembly mounted in said housing for movement between a closed circuit position and an open circuit position, said bridging assembly comprising:

an electrically conductive bridging member which electrically contacts the electrical contact portions in the closed circuit position,

a reciprocally movable shaft mounted in said housing, said shaft having means engaging a latching means,

means mechanically connecting said electrically conductive bridging member to said shaft, said means permitting the shaft to rotate about its axis without moving the bridging member; spring means biasing said reciprocally movable bridging member in the open circuit position; latching means operatively associated with said reciprocally movable bridging assembly for holding said bridging member in the closed circuit position; and,

movable trigger means connected to said latching means for unlatching said bridging member upon movement of the trigger means.

2. The switch of claim 1 further characterized by said reciprocally movable shaft being electrically conductive and said means mechanically connecting said shaft and bridging member providing electrical isolation between the shaft and bridging member.

3. The switch of claim 1 further characterized by said shaft having a reduced diameter portion with a right-angle shoulder at one end of said reduced diameter portion and a sloping shoulder at the other end and, said latching means engaging said right-angle shoulder in the closed circuit position.

4. The switch of claim 3 wherein said latching means comprises:

a. a latching shaft having a transverse groove which forms a flat surface with two interior shoulders and two exterior edges, said latching shaft being rotatably mounted in said housing with the longitudinal axis thereof transverse at a right angle to the longitudinal axis of said reciprocally mounted shaft; and

b. spring means rotatably urging one of said latching shaft flat surface exterior edges against the right-angle shoulder of said reciprocally movable shaft in the closed circuit position.

5. The switch of claim 4 wherein said spring means comprises:

a. a longitudinal member secured to said latching shaft at a right angle to the longitudinal axis of the latching shaft; and

b. a spring connected between one end of said longitudinal member and the housing, said spring exerting a force upon said longitudinal member in a first direction.

6. The switch of claim 5 further characterized by said trigger means moving said longitudinal member in a second and opposite direction to the

direction of the spring force exerted upon the longitudinal member. 9. The switch of claim 6 wherein said trigger means comprises a manually actuated, spring-loaded, plunger which operatively engages said

longitudinal member. 8. The switch of claim 6 wherein said trigger means comprises an electrically actuated solenoid having a plunger mechanically connected to said longitudinal member.