Automatic temperature and humidity regulation – Thermostatic – With pressure control
Reissue Patent
1992-06-26
2001-10-30
Tapolcai, William E. (Department: 3744)
Automatic temperature and humidity regulation
Thermostatic
With pressure control
C062S225000
Reissue Patent
active
RE037423
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to systems for controlling the flow of refrigerant in a refrigeration or air conditioning system of the type employing the well known mechanical thermal expansion valve. Typically, valves of this type have an auxiliary passage therethrough adapted for attachment to the discharge line of the refrigerant evaporator for receiving flow therefrom and for connection to the compressor suction return line. The auxiliary passage through the valve body provides a convenient location to sense the temperature of the evaporator discharge for purposes of providing an electric control signal which may be employed in a microcomputer for controlling the operation of the compressor clutch and condenser cooling fan.
Where it is desired to provide electrical sensing of the temperature in the auxiliary refrigerant passage in the thermostatic expansion valve, it has been found desirable to employ a thermistor in the passage for direct fluid temperature sensing. However, providing the mounting of the thermistor through the valve block from the exterior thereof and to provide adequate sealing around the thermistor for preventing leakage of the gaseous refrigerant has been troublesome in high volume mass production. Heretofore, it has been the practice to mount the thermistor on a metal flange and secure the flange to the periphery of a port formed in the valve body to access the auxiliary refrigerant passage. This technique for mounting the thermistor as a sub-assembly has been found to troublesome in high volume production of the valves where breakage of the thermistor has been experienced during the sealing operation which typically employ metal staking. Accordingly, it has been desired to provide a way or means of attaching a thermistor to a sensing port in the valve block after the port has been sealed to retain the pressurized gaseous refrigerant.
It has further been desired in providing a refrigerant temperature sensor in a thermal expansion valve passage to incorporate electronic circuitry at the thermistor location in order that the circuitry may be heat sinked to the low temperature valve block and thereby provide cooling for solid state switching devices handling substantial electrical current flow.
SUMMARY OF THE INVENTION
The present invention provides a mechanical thermal expansion valve for controlling refrigerant flow in a refrigeration or air conditioning system. An auxiliary passage is provided in the valve block for permitting refrigerant discharging from the evaporator to flow through the block to the compressor suction return port. A thermistor is disposed through a sensing port in the valve block to sense temperature of the refrigerant flowing and the refrigerant return passage. In one embodiment, a cup shape closure has the closed end thereof received in the sensing port with the periphery thereof sealed about the port. A thermistor is received in the cup from the exterior thereof and secured therein with thermally conductive grease disposed to provide heat transfer between the wall of the cup and the thermistor. The thermistor is preferably mounted on a printed circuit board received in a cup-shaped cover with the closed end extending exteriorly of the body with the open end sealed about the periphery of the sensing port. An electrical connector extends from the printed circuit board through the wall of the cover and exteriorly thereof for electrical connection thereto. The printed circuit board is potted in the cup and may contain power switching devices which are cooled by the refrigerant contacting the potting compound surrounding the printed circuit board.
REFERENCES:
patent: 3478534 (1969-11-01), Matthies
patent: 4065939 (1978-01-01), Thornberry et al.
patent: 4660387 (1987-04-01), Usami
patent: 4819443 (1989-04-01), Watanabe et al.
Glennon Thomas Francis
Torrence Robert James
Eaton Corporation
Johnston R. A.
Tapolcai William E.
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