US2787687A

US2787687A - Contacts for electric circuit breakers

Info

Publication number: US2787687A
Application number: US563823A
Authority: US
Inventors: Hall Richmond Ernest
Original assignee: Plessey Co Ltd
Current assignee: Plessey Co Ltd
Priority date: 1954-12-29
Filing date: 1956-02-06
Publication date: 1957-04-02
Anticipated expiration: 1974-04-02

Description

April 2, 1957 R. E. HALL CONTACTS FOR ELECTRIC CIRCUIT BREAKERS Filed Feb. 6, 1956 INVENTOR RICHMOND E. HALL.

United States Patent 2,787,687 CONTACTS FOR ELECTRIC CIRCUIT BREAKERS Richmond Ernest Hall, Ilford, England, asslgnor to The Plessey Company Limited, llford, England, a British company Application February 6, 1956, Serial No. 563,823

3 Claims. (Cl. 200-166) This invention relates to contacts for electric circuit breakers.

The object of the invention is to provide a contact member in compact form possessing a high degree of resilience, which is also relatively cheap to produce.

The invention essentially consists of a moving contact member which is constructed from a blade spring of which the opposed ends are each fitted with electrical contacts and wherein the intermediate portion of said spring is bent in a returning curve. The bending or folding of the intermediate portion of said spring increases the resiliency of the contact-carrying ends, so that during the usual follow-through action against the fixed contacts a wiping action will generally occur between the contacting surfaces.

An electrical contact is fixed to the respective ends of the spring for engagement with similar fixed contacts. In the case of a two-way switch, contacts are fixed to both faces of the spring to engage with similar fixed contacts when moved in alternate directions from the neutral or open position.

A feature of the invention is that the intermediate portion of the spring leaf is provided with means for rockably mounting the moving contact member in a suitable carrier.

Thus from one aspect the invention consists in a balanced contact member, comprising a blade spring having contacts at each end and being bent to include an S bend between said contacts, whereby the resilience of the blade spring is increased for a given distance between said contacts, said blade spring being formed with a pair of aligned integral lugs projecting laterally from the two edges of the blade spring approximately halfway between the two contacts. The leaf spring may be laminated, preferably with a number of thin sections to provide increased resiliency.

The accompanying drawing illustrates one embodiment of this invention. Figure 1 is an exploded perspective view of a contact assembly for an electrical relay or other circuit breaker having two contact members, one of which has been omitted to expose more details of the contact-carrier structure, and

Figure 2 is a section through part of a contact member.

Referring now to the drawing, the contact member consists of a spring blade of suitable metal having the intermediate portion folded to approximately an 8- formation. The longitudinal edges of the centre limb of the folded section are formed with. projecting lugs 12. The two ends of the spring blade 10 co-planar and carry each a

double contact element

13, 14.

Where the circuit breaker is to be used for heavy currents and in order to obtain a higher degree of resilience, the spring blade 10 carrying the

contact elements

13, 14 may consist of several thin laminations, as indicated at 10a, 10b, 10c and 10d in Figure 2. The latter figure also shows the manner in which the

contact elements

13, 14 are secured to the blade 10.

In the contact assembly illustrated in Figure 1 a plurality of contact members 1 are rockably mounted by their attachment lugs 12 in elongated apertures 15 of a con- 2,787,687 Patented Apr. 2, 1957 tact-holder bar comprising two identical bar elements 2. These elements are joined, with their corresponding faces 20 in contact, by spring rings or the like (not shown) engaging notches 21 at the back of each element 2 adjacent each end theerof. Grooves 22 extend across the face 20 of each member 2 and are so arranged and dimensioned that each pair of corresponding grooves 22 forms a passage which when the two members 2 are assembled with the contact members 1 in position, will accommodate the centre portion of the blade 10 and confine it against lateral movement while allowing it to rock about the lugs 12. The apertures 15 are somewhat wider than the thickness of these lugs so as to allow a limited amount of such rocking movement. The construction may be adapted to a variety of uses by mounting in a pair of bar members 2 of suitable length two or more contact members 1, each being accommodated in a separate pair of grooves 12 and pivoted in apertures 15 as hereinabove described. The contact members 1 constitute the movable contacts, which will co-operate with suitably mounted stationary contacts. In all cases equal contact pressures at the two sides can be maintained irrespective of minor inaccuracies in the location of the contacts, due to the rockable mounting of the members 1. Any conventional form of mechanical means may be used for actuating the bar assembly to open and close the circuit or circuits.

It will be evident from the foregoing description that the invention provides flexible contact member which when brought into engagement with fixed contacts provides a wiping action which in operation tends to clean the contact surface.

What is claimed is:

1. A balanced contact member, comprising a blade spring having contacts at each end and being bent to include an S bend between said contacts, whereby the resilience of the'blade spring is increased for a given distance between said contacts, said blade spring being formed with a pair of aligned integral lugs projecting laterally from the two edges of the blade spring approximately halfway between the two contacts.

2. A balanced contact member, comprising a blade spring having two coplanar end portions, integrally connected by an intermediate portion bent to a substantially S-like shape about axes parallel to the plane of said end portions and perpendicular to a line connecting said portions, and contact elements secured to each said end portion, the centre of said S-like shape being perpendicular to the plane of said end portions and provided at its two sides with aligned integral lugs.

3. A contact assembly for electrical relays and like contact devices, comprising a bar formed by a pair of complementary bar elements of insulating material having mutually facing transverse grooves jointly forming passages across said bar and having apertures extending through the bar transversely to the bar elements and to the grooves, said apertures intersecting the said passages and being elongated in the direction of the bar, and balanced contact members, as claimed in claim 2, each extending through one of said passages with its contact elements on the two end portions exposed outside the bar and with its lugs lodged in said apertures, the dimensions beingsuch as to allow a limited amount of rocking movement of said lugs in said apertures to balance contact pressures.

References Cited in the file of this patent UNITED STATES PATENTS 998,786 Loefiier July 25, 1911 2,529,652 Dicke Nov. 14, 1950 2,532,305 Heller Dec. 5, 1950 2.626.334 Koenig Jan. 20, 1953