Thermally actuatable auxiliary electrical switch apparatus

• US 5,870,014 A
• Filed: 10/11/1996
• Issued: 02/09/1999
• Est. Priority Date: 10/11/1996
• Status: Expired due to Term

• Current Assignee: Sensata Technologies Massachusetts Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Racine, James T., Raulino, Alfred, Nield, Joseph G. Jr.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Vortman, Anatoly
• Application Number:
  US08/729,606
• Time in Patent Office: 851 Days
• Field of Search: 337/85, 337/89, 337/97, 337/100, 337/101, 337/102, 337/112, 337/333, 337/342, 337/343, 337/377, 337/379, 337/380, 337/349, 337/56, 361/103, 361/105, 361/31, 361/32, 318/783, 318/778, 318/767
• US Class Current: 337/362
• CPC Class Codes: F25B 31/02 of motor-compressor units
• CPC Class Codes: H01H 61/002 Structural combination of a time delay electrothermal relay with an electrothermal protective relay, e.g. a start relay
• CPC Class Codes: H01H 61/02 wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively

Abstract

A thermally actuatable auxiliary switch (10, 10'"'"', 100) used with a refrigerator compressor system (60) has a generally U-shaped bimetallic element (12) mounted at one end on a base plate (16, 16'"'"', 102) and with a movable contact (28) mounted on the high expansion side (12a) of the bimetallic element in alignment with a stationary contact (32) mounted on a stationary contact support (18, 18'"'"', 116). A thermal generator (34) in the form of a PTC pill (36) wire-wound resistor (28), or other electrically energizable heater or in the form of a discharge tube (60e) of a compressor, provides heat to the bimetallic element (12) causing it to deflect after the solid state starter (50) has switched to its high resistance state to switch out the solid state starter while the compressor motor remains energized.

Claims

1. Thermally actuable electrical switch apparatus to de-energize an electric motor starter electrically connected serially to a start winding of a split-phase motor upon starting of the motor to save power used to run a compressor system comprising an electrically conductive, substantially U-shaped creep type bimetallic element having an outer layer of high expansion material and an inner layer of low expansion material and having first and second ends, an electrically conductive base plate having opposed first and second sides, a stationary contact support surrounding said first and second sides of said base plate with a layer of electrically insulative material interposed between the base plate and the stationary contact support thereby electrically isolating said stationary contact support from the base plate, the stationary contact support mounting a stationary contact, a first end of the bimetallic element being mounted on and electrically connected to the base plate, the second end of the bimetallic element mounting a movable contact on the outer layer aligned with the stationary contact, the movable contact being movable into and out of electrical engagement with the stationary contact upon selected changes in temperature causing deflection of the bimetallic element and means to provide actuation heat to the bimetallic element not requiring electric energy to directly provide such actuation heat comprising a discharge tube of said compressor system, the switch apparatus being mounted in heat transfer relation to the discharge tube, the stationary and movable contacts being serially connected to the solid state electric motor starter.

2. Thermally actuatable electrical switch apparatus according to claim 1 in which a housing having a bottom wall with a cut-out portion formed in the bottom wall, the bimetallic element mounted in the housing with a portion received in the cut-out portion of the bottom wall, a heat conductive clip member having a heat sink plate portion, a pair of tube attaching arms aligned with and spaced from one another extending in a direction away from the plate portion and means to attach the clip member to the housing with the heat sink portion disposed at the cut-out portion of the bottom wall in intimate thermal relation with the bimetallic element.