GB2242570A

GB2242570A - "Contactor and switch therefor"

Info

Publication number: GB2242570A
Application number: GB9006825A
Authority: GB
Inventors: Eric Albert Somerfield
Original assignee: Crabtree Electrical Industries Ltd
Current assignee: Crabtree Electrical Industries Ltd
Priority date: 1990-03-27
Filing date: 1990-03-27
Publication date: 1991-10-02
Also published as: GB9006825D0

Abstract

A switch for use with a conventional contactor wherein the contactor comprises a housing 6, pairs of terminals 8a, 8b, each terminal comprising an L-shaped terminal element 10 and a screw 12, and respective holes 14 located directly above the screws to enable the screws to be engaged by a screw driver, and the switch comprises a housing (20) (see Fig. 4) from which a pair of hollow legs 26 protrude, adapted to be located in a pair of apertures 14 over a pair of terminals 8a, 8b, and a contact element 34 (e.g. spring steel wire), contact portions 34c of the contact element entering apertures 14 above the screws 12. Depression of a switch member 40 causes contact portions 34c to engage the terminals. Housing 20 is attached to the contactor via catch members 28. <IMAGE>

Description

tittle: "Switches" Description of Invention This invention is concerned with improvements relating to switches, particularly to switches suitable for use with contactors.

A conventional contactor comprises a housing locating a plurality of pairs of terminals, and electro-magnetic switching mechanism in the housing to switch between respective pairs of terminals as may be desired in the operation of the contactor. Conventionally each terminal comprises an angle bracket, of Lshape in cross-section, and connection means, conventionally in the form of a screw, whereby wiring may be secured to the terminal.

On occasion it is desired to provide an auxiliary switch mechanism in conjunction with such a contactor, which may for example be a start switch. Such a switch will be operative to bridge one pair of terminals by [conventionally] a manual operation.

Difficulty has been encountered in providing such an auxiliary switch on a contactor, particularly in that the conventional contactor housing shields the terminals for safety reasons.

According to this invention there is provided, in combination, a contactor comprising a housing and including at least one pair of spaced terminals, and an auxiliary switch for the contactor, the switch comprising a housing adapted to be secured to the contactor housing, a contact element in the switch housing, and a switch member operable to cause the contact element to move between a first position in which it is spaced from at least one of the terminals, and a second position in which it provides an electrically conductive path between said pair of terminals.

In this manner an auxiliary switch for a contact member may readily be provided, such as may be required for a starting operation, and the auxiliary switch secured to the contactor housing when it is desired to provide the contactor with such a switching facility.

Preferably the contact element is adapted to contact respective parallel surfaces of the terminals, as may be conventionally provided on a contactor.

Preferably the contact element is adapted to engage respective outwardlysurfaces of the terminals, by movement of approach of respective contact portions of the contact element.

Preferably the contactor and switch comprise complementary interfitting formations to enable the switch to be snap-fitted to the contactor: thus preferably the switch comprises formations cooperable with formations provided on an existing or standard contactor.

Preferably when the switch is so mounted on the contactor, the contact element, in particular the contact portions thereof, protrude into access holes in the contactor housing, such as may be provided for access to screws of the terminals.

According to this invention there is also provided an auxiliary switch for the contactor, the switch comprising a housing adapted to be secured to the contactor housing, a contact element in the housing, and a switch member to move the contact element between a first condition spaced from a pair of terminals in the contactor and a second condition conductively engaging said contacts, movement of the contact element from its first to its second condition involving movement of approach between respective contact portions of the contact element.

Preferably the switch member is biased [such as by a spring bias], from a position corresponding to the second condition of the contact element to a position corresponding to the first condition of the contact element, preferably Wy the use of a separate spring element.

Preferably the contact element is resilient, and at rest adopts a position in which the contact portions thereof are spaced apart, but which may be resilient deformed to cause the contact portions to move together, preferably in the form of a pincer movement, to effect switching. Thus conveniently the contact element is afforded by a length of wire bent to provide a bridge portion and two side arms extending from the bridge portion, each side arm terminating at an inwardly-turned contact portion.

Preferably the switch member comprises side arms, each adapted to engage a respective side arm of the contact element, and to cause, on movement of the switch member, movement of the contact portions of the contact element to effect the switching operation.

Most conveniently the switch housing comprises location means enabling the switch accurately to be located with respect to the contactor housing, and preferably the location means comprises legs adapted to fit into apertures of the contactor housing. Most conveniently the legs are adapted to be located in access apertures for the terminal screws, and most conveniently the legs are hollow, with the side arms of the contact element being located within the hollow legs, ensuring, on assembly of the switch the contactor, that the contact element, at least the contact portions thereof, pass through said apertures to enable the contact element to engage the terminal elements.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of a switch which is the preferred embodiment of the invention, having been selected for the purposes of illustrating the invention by way of example, the switch being adapted for use in conjunction with a conventional contactor, the combination of contactor and switch also being illustrative of the invention in certain of its aspects.

In the accompanying drawings: FIGURE 1 is a perspective view of the switch which is the preferred embodiment of the invention; FIGURE 2 is a sectional view taken on the line 2-2 of Figure 1; FIGURE 3 is a sectional view showing the switch in position on the contactor; and FIGURE 4 is a perspective view showing details of the assembly together of the switch with a conventional contactor.

The switch which is the preferred embodiment of this invention is for use with a conventional contactor, particularly a contactor of the kind shown in Figures 3, and 4, comprising a housing 6, within which a plurality of pairs of terminals 8a 8b are located, each terminal comprising an L-shaped terminal element 10, and a screw 12 by which wiring [not shown] may be secured to the terminal.

Located directly above the screws 12 are respective holes 14, by which a screw driver or similar tool may be inserted into the housing to loosen or tighten the screws 12 as necessary. The housing also comprises additional apertures such as are indicated by the numeral 16 in the drawings.

The switch which is the preferred embodiment of the invention comprises a housing 20 defining a primary cavity 22 and a secondary cavity 24.

Protruding from the bottom of the housing are a pair of hollow legs 26, adapted to be located in a pair of apertures 14 over a pair of terminals 8a, 8b, and a plurality of catch members 28 adapted to be located in other apertures 14 or 16.

Extending generally mid-way across the housing is a web 30, provided with a downwardly-extending hollow boss 32.

Located in the housing is a contact element 34, in the form of a length of spring steel wire bent generally into the form of a U. A central bridge portion 34a of the element 34 extends across an upper surface of the web 30 to one side of the hollow boss 32, with side arms 34b of the element extending adjacent to the side walls, and passing into respective ones of the hollow legs 26. As will be seen from Figure 2, the side arms 34b terminate at inwardly-directed contact portions 34c. Lower portions of the side arms 34b, including the contact portion 34~, are located at least in a rest condition of the switch, within the hollow legs 26.

Located in an upper part of the housing above the web 30 is a switch member 40, comprising an elongate cylindrical stem 41 slidable received within the hollow boss 32. Extending around the hollow boss, and acting between the head of the switch member and the web 30 is a spring 42, urging the switch member 40 into an outer or operative position, as is shown in Figure 3.

Conveniently the spring also acts against the bridge portion 34a of the contact element, and urges the bridge portion into contact with the web 30.

Extending downwardly from the head of the member 40 on either side thereof are two arms 44a, 44b, each arm having an inwardly-facing groove in which one of the two side arms 34b of the contact element is located.

In the assembly of the switch on the contactor, the hollow legs are located in a pair of apertures 14, with the catches located in appropriate apertures 16, the contact portions 34e of the contact element entering the apertures 14 and being located above the screws 12, and, at rest spaced from the vertical limbs of the terminal element 10. It will be appreciated that, with the switch in its inoperative position, the contact portions 34 of the contact element are withdrawn so as to be located almost wholly within the circumference of the hollow legs 26, permitting the contact portions to be located within the housing of the contactor.On depression of the switch member 40 against the action of the spring 42 the side arms 44 of the switch engage the side arms of the contact element, to urge the contact portions 34c inwardly into engagement with the vertical limbs 10a of the terminal element, in a pincer-like movement, to establish conductive contact therebetween. This may be utilised to effect a starting operation in relation to the contactor, and on release of the switch 40, the side arms are retracted, allowing the contact element to open, with the contact portions 34e thereof separating from the terminal elements 10.

The secondary cavity 24 may be utilised to house ancilary electrical equipment, such as additional switches.

It will be appreciated that any erosion of the contact portions of the contact element which may take place, which may be caused by sparking, will be self-compensating, since the switch 40 is depressed to a position at which contact is made, and to some extent this is irrespective of the amount of movement of the contact element which is required to establish contact.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in the terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

ClAIMS:

1. In combination, a contactor comprising a housing and including at least one pair of spaced terminals, and an auxiliary switch for the contactor, the switch comprising a housing adapted to be secured to the contactor housing, a contact element in the switch housing, and a switch member operable to cause the contact element to move between a first position in which it is spaced from at least one of the terminals, and a second position in which it provides an electrically conductive path between said pair of terminals.

2. The combination according to Claim 1 wherein the contact element is adapted to contact respective parallel surfaces of the terminals.

3. The combination according to one of Claims 1 and 2 wherein the contact element is adapted to engage respective outwardly- facing surfaces of the terminals, by movement of approach of respective contact portions of the contact element.

4. The combination according to any one of the preceding claims wherein the contactor and switch comprise complementary interfitting formations to enable the switch to be snap-fitted to the contactor.

5. The combination according to any one of the preceding claims wherein the switch comprises formations cooperable with formations provided on an existing or standard contactor.

6. The combination according to any one of the preceding claims wherein when the switch is so mounted on the contactor, the contact element protrudes into access holes in the contactor housing.

7. An Auxiliary switch for a contactor, the switch comprising a housing adapted to be secured to the contactor housing, a contact element in the housing, and a switch member to move the contact element between a first condition spaced from a pair of terminals in the contactor and a second condition conductively engaging said contacts, movement of the contact element from its first to its second condition involving movement of approach between respective contact portions of the contact element.

8. The invention according to any one of the preceding claims wherein the switch member is biased from a position corresponding to the second condition of the contact element to a position corresponding to the first condition of the contact element.

9. The invention according to any one of the preceding claims wherein the contact element is resilient and at rest adopts a position in which the contact portions thereof are spaced apart, but which may be resiliently deformed to cause the contact portions to move together to effect switching.

10. The invention according to any one of the preceding claims wherein the contact element is afforded by a length of wire bent to provide a bridge portion and two side arms extending from the bridge portion, each side arm terminating in an inwardly-turned contact portion.

11. The invention according to Claim 10 wherein the switch member comprises side arms, each adapted to engage a respective side arm of the contact element and to cause, on movement of the switch member, movement of the contact portions of the contact element to effect the switching operation.

12. The invention according to any one of the preceding claims wherein the switch housing comprises location means enabling the switch to be located with respect to the contactor housing.

13. The invention according to Claim 12 wherein the locations means comprises legs adapted to fit into apertures of the contactor housing.

14. The invention according to Claim 13 wherein in the legs are adapted to be located in access apertures for the terminal screws of the contactor housing.

15. The invention according to one of Claims 13 and 14 wherein the legs are hollow, with the side arms of the contact element being located within the hollow legs.

16. In combination, a contactor comprising a housing and including at least one pair of spaced terminals and an auxiliary switch for the contactor, constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

17. An auxiliary switch for a contactor, constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

18. Any novel feature or novel combination of features as hereinbefore described and/or as shown in the accompanying drawings.