Refrigeration – Automatic control – Preventing – removing or handling atmospheric condensate
Reexamination Certificate
1999-09-08
2001-01-30
Tanner, Harry B. (Department: 3744)
Refrigeration
Automatic control
Preventing, removing or handling atmospheric condensate
C062S155000, C062S156000, C062S230000, C062S236000
Reexamination Certificate
active
06178760
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application relates to and incorporates herein by reference Japanese Patent Application No. 10-271202 filed on Sep. 25, 1998.
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner system and method for electric vehicles.
Heat pump type air conditioner systems employing electrically-driven compressors are used widely as air conditioners mounted on electric vehicles from the standpoint of ensuring a self heat generating source, reducing air pollution and saving electric power energy. In those heat pump type air conditioner systems, however, the exterior heat exchanger is used as an evaporator at the time of heating operation to exchange heat between low temperature, low pressure refrigerant and exterior air. Thus, frosting occurs on the surface of the heat exchanger at the time of heating operation. The frosting lessens the operation performance of exchanging heat with the exterior air and hence the heating operation performance.
U.S. Pat. No. 5,555,737 (JP-A-7-212902) proposes to defrost the heat exchanger in the course of battery charging by using excess electric power generated immediately before completing the battery charging. The heat exchanger will not be defrosted sufficiently when the battery charging is stopped midway of the battery charging, that is, before the battery charging is completed. As a result, a sufficient heating performance for a quick heating (warm-up) cannot be provided as the heating operation starts with frost still remaining on the heat exchanger.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an electric vehicle air conditioner system and method vehicles which ensures a defrosting operation to improve a heating operation.
According to the present invention, an air conditioner system for electric vehicles has an exterior heat exchanger, which is used as an evaporator at the time of heating operation. A control unit monitors the heating operation during a vehicle running. When an electric vehicle is at rest after the heating operation to charge its secondary battery with an electric power from an external power source, the control unit checks whether the monitored heating operation continued for a predetermined time period under a low exterior air temperature below a predetermined temperature. The control unit drives a refrigeration cycle for a defrosting operation and starts a charging operation of the secondary battery after the completion of the defrosting operation, when the control unit determines that the heating operation continued for the predetermined time period. Preferably, the control unit varies a defrosting operation period to be longer as the exterior air temperature is lower.
Alternatively, the control unit executes the defrosting operation when a compressor rotation speed and a refrigerant pressure in a refrigeration cycle are within a defrosting range determined by the compressor rotation speed and the refrigerant pressure.
REFERENCES:
patent: 5284025 (1994-02-01), Kajitani et al.
patent: 5305613 (1994-04-01), Hotta et al.
patent: 5555737 (1996-09-01), Takeo et al.
patent: 5586448 (1996-12-01), Ikeda et al.
Iritani Kunio
Tanaka Masaya
Denso Corporation
Harness Dickey & Pierce PLC
Tanner Harry B.
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