Refrigerant cycle system having hot-gas bypass structure

Details Refrigerant cycle system having hot-gas bypass structure Refrigerant cycle system having hot-gas bypass structure

2000-06-12

2001-07-31

Tanner, Harry B. (Department: 3744)

Refrigeration

With indicator or tester

Operatively correlated with automatic control

C062S129000

Reexamination Certificate

active

06266965

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application is related to and claims priority from Japanese Patent Applications No. Hei. 11-183382 filed on Jun. 29, 1999, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigerant cycle system having a hot-gas bypass structure, in which hot gas refrigerant discharged from a compressor is directly introduced into an evaporator after being decompressed while bypassing a condenser during a heating mode. The refrigerant cycle system accurately determines a refrigerant shortage during the heating mode, and is suitable for a vehicle air conditioner.
2. Description of Related Art
In a conventional vehicle air conditioner, air blown into a passenger compartment is heated by using hot water (engine-cooling water) flowing through a heating heat exchanger as a heating source during a heating mode in the winter. In this case, when temperature of hot water is low, the temperature of air blown into the passenger compartment is lowered, and heating capacity for the passenger compartment becomes insufficient.
JP-A-5-272817 describes a refrigerant cycle system which can set a heating mode using a hot-gas refrigerant bypassing structure. In the conventional system, when temperature of hot water is lower than a predetermined temperature at an engine start time, hot-gas refrigerant discharged from a compressor is introduced into an evaporator while bypassing a condenser so that air passing through the evaporator is heated by heat from the gas refrigerant. That is, the operation of the refrigerant cycle system is switched so that the evaporator is used as a cooling unit during a cooling mode and is used as a heating unit during the heating mode.
However, in the conventional system, when a refrigerant amount within a hot gas bypass cycle is insufficient, refrigerant staying in the condenser is only recovered. Therefore, even when the refrigerant amount in the refrigerant cycle is greatly reduced due to a refrigerant leakage from a component or a pipe of the refrigerant cycle system, the operation of the compressor is continuously performed. Thus, in this case, the compressor may be damaged.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the present invention to provide a refrigerant cycle system having a hot-gas bypass structure, which protects a compressor even when a refrigerant leakage is caused during a heating mode.
According to the present invention, in a refrigerant cycle system, a hot-gas bypass passage through which refrigerant discharged from a compressor directly flows into a refrigerant inlet side of an evaporator is provided, so that the evaporator is used as a radiator during a heating mode due to the hot-gas bypass. The refrigerant cycle system includes a detecting unit for detecting a physical amount indicating a state of refrigerant flowing through the hot-gas bypass passage during the heating mode, and a control unit for controlling operation of the compressor. The control unit determines a refrigerant shortage based on the physical amount, and stops the operation of the compressor when the refrigerant shortage is determined. As a result, during the heating mode due to the hot-gas bypass, the compressor is accurately protected when a refrigerant leakage is caused in the refrigerant cycle system.


REFERENCES:
patent: 4220010 (1980-09-01), Mueller et al.
patent: 5481884 (1996-01-01), Scoccia
patent: 5586445 (1996-12-01), Bessler
patent: 6098412 (2000-08-01), Porter et al.
patent: 6205798 (2001-03-01), Porter et al.
patent: 5-272817 (1993-10-01), None

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