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US 8,853,582 B2Granted
Electrical switch with shear force contact weld release
AssigneeIllinois Tool Works Inc.
InventorsAdrian J. Tengler, Michael S. Osvatic, Michael K. Hintz
Life of this patent
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Abstract
An electrical switch provides a center contact moving between two outer contacts, at least one of which is mounted on a lever. In the event of a contact weld forming between the center contact and the lever mounted contact, unison motion of the lever mounted contact following the center contact during switching causes a strong shear force tending to break the weld. In one embodiment, a fulcrum wall striking the lever of the lever mounted contact causes increased angulation between the contacts so that unison motion rotates and peels the contacts apart.
Claims9
An electrical switch comprising:
- a housing;
- a first contact;
- a second contact supported at a distal end of a first lever, the first lever movably supported by the housing to move the second contact under influence of a switch operator between a first position separated from the first contact and a second position contacting the first contact;
- wherein the first contact is supported at a distal end of a second lever, the second lever movably supported by the housing to follow the second contact moving from the second position to the first position;
- wherein proximal ends of the first and second levers are positioned in the housing to provide a shear force between the first and second contact when the first contact follows the second contact from the second position to the first position;
- wherein the first and second levers are electrically conducting to provide an electrical path from the first and second contacts to corresponding conductors passing through the housing;
- wherein the first lever is substantially rigid to rotate between the first and second position at a pivot point between the lever and a conductive support;
- wherein the switch operator communicates with the first lever by means of an over-center spring operating to bias the first lever into engagement with the conductive support at the pivot point.
5 more elements
A method of operating an electrical switch having:
- a housing;
- a first contact;
- a second contact supported at a distal end of a first lever, the first lever movably supported by the housing to move the second contact under an influence of a switch operator between a first position separated from the first contact and a second position contacting the first contact;
- wherein the first contact is supported at a distal end of a second lever, the second lever movably supported by the housing to follow the second contact moving from the second position to the first position when the first and second contacts are connected by a welding;
- wherein proximal ends of the first and second levers are positioned in the housing to provide a shear force between the first and second contact when the first contact follows the second contact from the second position to the first position by a welding at the second position;
- wherein the first and second levers are electrically conducting to provide an electrical path from the first and second contacts to corresponding conductors passing through the housing;
- wherein the first lever is substantially rigid to rotate between the first and second position at a pivot point between the lever and a conductive support;
- wherein the switch operator communicates with the first lever by means of an over-center spring operating to bias the first lever into engagement with the conductive support at the pivot point, the method comprising the steps of:
- (a) activating a switch operator to move the second contact from the first position to the second position to provide for electrical current flow between the first and second contacts to produce a welding between the first and second contacts;
- and
- (b) releasing the switch operator to cause the second contact to move from the second position to the first position to generate a shear force breaking the weld between the first and second contacts.
8 more elements
Dependencies are inferred from the claim text.