AUTOMATICALLY RESETTABLE THERMAL SWITCH

• US 3,706,952 A
• Filed: 02/02/1972
• Issued: 12/19/1972
• Est. Priority Date: 02/02/1972
• Status: Expired due to Term

• Current Assignee: Robert P. Alley
• Original Assignee: Robert P. Alley
• Inventors: Alley, Robert P.
• Primary Examiner(s): Gilheany, Bernard A.
• Assistant Examiner(s): Grimley, A. T.
• Application Number:
  US05/222,951
• Time in Patent Office: 321 Days
• Field of Search: 337/3,13,70,73,333,343,348,356,358,362,365,367
• US Class Current: 337/348
• CPC Class Codes: H01H 37/60 Means for producing snap action inherent in bimetallic element H01H37/54; caused by a magnet H01H37/66

Abstract

A thermal switch is provided which uses a bimetal element to provide the force to open and close a set of contacts. The bimetal element is initially restrained from opening the contacts by a latch mechanism which uses an eutectic material for determining the temperature at which the latch mechanism will release. Upon a sufficient drop in the ambient temperature, sufficient force is generated in the bimetal element to cause the bimetal to slip past a shaped surface on the latch mechanism thereby resetting of the switch.

Claims

1. An automatically resettable thermal switch, comprising:

a base;

a resilient member having one end mounted to said base and a free end;

a rigid member mounted to said base and extending in juxtaposition with said resilient member;

an eutectic material, having a predetermined phase change temperature range, located between said resilient member and said rigid member for normally securing said resilient member to said rigid member; and

a bimetal member having one end mounted on said base and a free end, a first contact mounted on said bimetal member and cooperating with a second contact mounted in relation to said base;

said free end of said bimetal member being constrained from moving said first contact relative to said second contact by said free end of said resilient member until the ambient temperature reaches the predetermined phase change temperature range of said eutectic material.

2. An automatically resettable thermal switch as set forth in claim 1 wherein said free end of said resilient member is provided with a shaped surface which allows said free end of said bimetal member to slide past said free end of said resilient member in response to a drop in ambient temperature below a predetermined temperature.

3. An automatically resettable thermal switch as recited in claim 1 wherein said alloy comprises 51.4 percent indium, 47.3 percent tin and 1.3 percent silver.

4. An automatically resettable thermal switch, comprising:

a base;

an elongated, rigid member mounted to said base;

an elongated, resilient member mounted to said base;

said resilient member overlying said rigid member and having a free end portion projecting beyond said rigid member;

an eutectic material, having a predetermined phase change temperature range, positioned between said rigid member and said resilient member for normally securing said resilient member to said rigid member;

an elongated, bimetal member mounted to said base;

a first contact mounted to said bimetal member and cooperating with a second contact mounted in relation to said base;

said bimetal member including a free end portion positioned in interfering relationship with said free end portion of said resilient member for constraining movement of said bimetal member until the temperature of said eutectic material reaches the phase change temperature range of said eutectic material;

said resilient membEr then being free to flex for allowing said bimetal member to move past said resilient member in one direction.

5. An automatically resettable thermal switch as set forth in claim 4 wherein said free ends of said resilient and bimetal numbers are formed with complimentary surfaces to facilitate movement of said bimetal member past said resilient member in the other direction.