# US 4,399,339 A · Electrical contact

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- Number: US 4,399,339 A
- Document ID: US4399339A
- Status: Granted
- Kind: A
- Application number: 06/239,216
- Filed: 1981-03-02
- Granted: 1983-08-16
- Earliest claimed: 1981-03-02
- Assignees: Cherry Electrical Products Corporation
- Inventors: William F. Storm
- Web page: https://patentgrep.com/patent/US4399339A

## CPC

- H01H 1/02: characterised by the material thereof {(containing gas-evolving material H01H33/765)}
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)

## Abstract

In one aspect of the invention, a sintered electrical contact having a contacting surface defining a plurality of voids is disclosed. The voids contain a corrosion retarding fluid which passes onto the contacting surface upon being worn down upon repeated engagement with a conductive element.

## Claims

### Claim 1

An electrical contact comprising:
a contacting surface, adapted for repeated engagement with a conductive element and defined by grains of electrically conductive material;
a plurality of voids defined by said grains; and
a corrosion retarding fluid deposited in at least some of said voids, said fluid maitaining its liquid state for all switching operations of said contact, so that the fluid passes from said voids onto said contacting surface as said contacting surface becomes eroded upon repeated engagement by said conductive element.

### Claim 2 (depends on 1)

The electrical contact defined in claim 1 wherein said contacting surface is formed by sintering said grains.

### Claim 3 (depends on 1)

The electrical contact defined in claim 1 wherein said fluid is disposed in said voids by vacuum impregnation.

### Claim 4 (depends on 1)

The electrical contact defined in claim 1 wherein said fluid is maintained in said voids by surface tension.

### Claim 5 (depends on 1)

The electrical contact defined in claim 1 wherein said grains are formed from a conductive metal excluding the class of precious metals.

### Claim 6 (depends on 1)

The electrical contact defined in claim 1 wherein said contacting surface is defined by grains of copper alloyed with a hardening agent.

### Claim 7

In a switch having at least two electrically conducting contact elements for making and breaking electrical contact with one another, the improvement of at least one of said contact elements comprising:
a porous matrix of electrically conducting particles, said porous matrix defining voids and having a contact surface for conductively contacting the other contact element, said particles forming protuberances on said surface; and
a corrosion retarding fluid disposed in at least some of said voids;
said fluid flowing from voids adjacent to said contact surface for coating the surface with fluid to prevent corrosion of the surface, the protuberances of the surface eroding in response to the making or breaking of conductive contact between the contact elements to open additional voids and to thereby release fluid to maintain the corrosion resistant coating of fluid on the contact surface.