US3171264A - Low-pressure and safety cut-in switch - Google Patents

Description

March 2, 1965 s. R. GRIFFIN 3,

LOW-PRESSURE AND SAFETY CUT-IN SWITCH Filed Jan. 23, 1961 EVAPORATOR U LITO COMPRESSOR A I FROM REcEIvER p- E:

COMPRESSOR CONDENSER T0 "nEcE|vER 8 0: IO j E 5 l3 II 9 7 2 I5 is IL] 2 42 O z E --20 2| '9 ,2o 1' TO I mENsER MOTOR FROM T: F COMPRESSOR :JQL [MENTOR B130 GERALD R. GRIFFIN RATOR REcEIvER United States Patent 3,171,264 LflW-PRESSURE AND SAFETY cur-us SWITCH Gerald R. Grifiin, 197 Hannasch St, San Antonio, Tex. Filed Earl. 23, 1961, Ser. No. 84,368 4 Claims. (Cl. 6Z2ti9) This invention relates generally to temperature sensitive switches, and is specifically concerned with a safety switch which ensures the operation of refrigerators, operating on low pressure cut-in controls, during cold weather,

Refrigerators which are operated by low pressure cut-in controls fail to cut-in if outside temperatures drop below a certain temperature. Under such conditions the actual refrigerator temperature will rise above the normally controlled temperature limits.

It is a primary object of this invention to provide a switch adapted to initiate operation of a refrigerator cycle when the external temperature about the outside of the refrigerator drops to a pre-set temperature.

It is a further object of this invention to provide a gas operated and mechanically actuated switch for refrigeration circuits, ensuring the continuing operation of the refrigerator under conditions of low external temperatures.

It is a still further object of this invention to provide a gas operated electrical switch responsive to low temperature actuation which is of simple constructon, elfective in operation, and may be manufactured at low cost.

The system of the invention includes a gas filled bulb which communicates with a pressure sensitive bellows through a capillary tube. rigidly secured to a frame, and the opposite end is adapted to actuate one end of a cantilever in response to expansion and contraction of the bellows. The opposite end of the cantilever engages with a flexible terminal which may be flexed to close a circuit by contact with a second terminal. The bulb is located near the high pressure side of the refrigerator circuit adjacent the condenser. During operation of the refrigeration cycle, the gas will be warm and the switch of my invention will remain in open circuit. However, if the low pressure control fails due to low outside temperature conditions, the refrigerator gases will be cooled and likewise the gas in the bulb will cause the switch to actuate and start the cycle. In this way the two control units are installed in the same circuit, the temperature sensitive switch of my invention only operating under cold weather conditions.

Further advantages and objects of this invention will become apparent from the following more detailed description of a preferred embodiment thereof, taken in conjunction with the attached drawing which illustrates diagramatically the components which combine to form the invention.

Referring now to the drawing wherein a block diagram illustrates a refrigeration system with various conventional components labeled, the numeral 1 represents a hollow bulb adapted to contain gas. One end of the bulb 1 is connected through a capillary tube 2 to the fixed end of a pressure sensitive cylindrical bellows 3. The bellows are adapted to expand and contract axially in response to variable gas pressures introduced therein through the capillary tube 2. Mounted externally on the free end 4 of the bellows 3 is a boss 5 which is adapted to link with one end 6 of a fulcrum arm 7. The arm 7 is pivoted on a transverse shaft 8 which is mounted between upstanding bearing tabs 9. The shaft is positioned relative to the arm 7 such that suitable mechanical advantage is delivered to the opposite end 10 of the arm. An insulating boss 11 is mounted beneath the end 10 of the arm 7.

The end 10 of the arm extends over a terminal board 12 having two spaced electrical terminals 13 and 14. The

One end of the bellows is 3,171,264 Patented Mar. 2, 1965 terminal 13 is electrically connected to a flexible conductor arm 15 which terminates with a contact 16. The remaining terminal 14 connects with a fixed electrical contact 1'7 through a conductor '18. The terminals connect in open circuit via the circuit wires 19 and '20 with the electric motor for driving the compressor. Also in the circuit is the low pressure cut-in control 21 in a line which parallels the contacts 16 and 17.

The bulb 1 is located adjacent the high pressure side of the refrigerator circuit, adjacent the condenser.

It will be appreciated that the dimensions of the above related components are a matter of choice. In operation, the unit is incorporated in the refrigerator circuit which is normally controlled by low pressure cut-in control 21. During conditions of normal external temperatures, the refrigeration gases will remain warm and such warmth will be transmitted to the gas filled bulb 1. The gas, so warmed, will be expanded causing the bellows to lengthen and maintain the contacts 15 and 17 in open circuit. In cold weather however, the gases in the refrigeration cycle become cooled and the pressure sensitive control 21 fails to operate. The low temperature will at this time cause a contraction of gas contained in the bulb 1, resulting in a shortening of the bellows 3. Such movement causes an anti-clockwise rotation of the fulcrum arm 7, and forces the flexible conductor arm 15 downwardly such that the contact 16 is moved into electrical engagement with the contact 17, closing the refrigerator motor circuit via wires 16 and 17. When, after adequate operation of the motor and compressor, the gas in bulb 1 warms, the bellows 3 will expand to open contacts 16 and 17.

Having described the invention in a preferred form, it will be appreciated that some modifications may be made to the precise configuration, without departing from the scope or spirit of the invention, as defined by the following claims.

I claim:

1. In a refrigerator system including a condenser, a refrigerator motor, and a low pressure control for operating the refrigerator motor; a temperature responsive means located near the condenser and responsive to the temperature of the refrigerant in the system; and means electrically connected to said motor and operated by'said temperature responsive means starting said motor when the temperature responsive means reacts to a predetermined low temperature at a time when said low pressure control may not be operating the refrigerator motor due to low external temperature and stopping said motor when the motor has run for a sufficient period of time to raise the temperature of the temperature responsive means.

2. The combination defined in claim 1 in which said temperature responsive means comprises a gas filled bulb.

3. The combination defined in claim 2 in which said means operated by said temperature responsive means includes a bellows communicating with said bulb and lever means operable to close terminal means to energize said motor.

4. The combination defined in claim 2 in which said means electrically connected to said motor includes contacts made when the temperature of the gas in the bulb falls and opened when the temperature of the gas in the bulb rises.

References Cited in the file of this patent UNITED STATES PATENTS 1,101,742 Hays June 30, 1914 1,208,691 Stickle Dec. 12, 1916 1,501,874 Wardenburg July 15, 1924 2,191,965 McGrath Feb. 27, 1940 2,195,954 Fields Apr. 2, 1940 2,435,530 Candor Feb. 3, 1948

Claims (1)

1. IN A REFRIGERATION SYSTEM INCLUDING A CONDENSER, A REFRIGERATOR MOTOR, AND A LOW PRESSURE CONTROL FOR OPERATING THE REFRIGERATOR MOTOR; A TEMPERATURE RESPONSIVE MEANS LOCATED NEAR THE CONDENSER AND RESPONSIVE TO THE TEMPERATURE OF THE REFRIGERANT IN THE SYSTEM; AND MEANS ELECTRICALLY CONNECTED TO SAID MOTOR AND OPERATED BY SAID TEMPERATURE RESPONSIVE MEANS STARTING SAID MOTOR WHEN THE TEMPERATURE RESPONSIVE MEANS REACTS TO A PREDETERMINED LOW TEMPERATURE AT A TIME WHEN SAID LOW PRESSURE

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