公开(公告)号：US3872685A

公开(公告)日：1975-03-25

申请号：US43383174

申请日：1974-01-15

Applicant: CONTROLS CO OF AMERICA

Inventor： MATTHIS ALAN A

IPC: F25D11/00 ,  A47F3/04 ,  F24F11/02 ,  F25B1/00 ,  F25B41/04 ,  F25B49/02 ,  G05D23/00

CPC classification number: F25B41/043 ,  A47F3/0478 ,  F25B49/02 ,  F25B2347/023 ,  F25B2400/22 ,  F25B2600/026

Abstract: Each of the two refrigeration systems incorporates an electric evaporator temperature control regulated by a solid state temperature switch which may be adjusted for a desired temperature and may be located in a remote location. In one system the control valve is located in the suction line between the evaporator and compressor and functions to throttle flow to the compressor when the temperature at the thermistor sensing probe falls below the set point. In the other system the temperature control valve functions as a hot gas bypass valve from the compressor outlet to the suction line between the evaporator and the compressor. The valve is opened when the temperature at the thermistor sensing probe falls below the set point. In either system operation of the temperature control valve acts to control pressure in the evaporator and thus controls the temperature. With the sensor located in the air stream, the system functions to control the air stream temperature and will compensate the system for frost build-up on the evaporator. The temperature control valve itself is preferably a ported sleeve-type valve actuated by a bimetallic stack energized by a heater regulated by the remote temperature sensing control. The temperature control includes a thermistor which forms part of an adjustable branch of a bridge circuit, the output of which is fed into a signal amplifier which, in turn, feeds into a power amplifier to give a desired voltage change per a selected increment of temperature deviation from the set point. In addition to giving remote sensing and adjustability, this system achieves close temperature control and more rapid pulldown of the system since there is a minimal modification of evaporator temperature/pressure until the desired temperature is reached. When used in a display case the system can incorporate an added resistance and switch to shift the set point to compensate for changed ambient conditions.