Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2003-02-27
2004-03-09
Norman, Marc (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S437000
Reexamination Certificate
active
06701731
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to and claims priority from Japanese Patent Applications No. 2002-53512 filed on Feb. 28, 2002, No. 2002-93768 filed on Mar. 29, 2002, No 2002-93769 filed on Mar. 29, 2002, No. 2002-155604 filed on May 29, 2002 and No. 2002-372092 filed on Dec. 24, 2002, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cold-storage type air conditioner for a vehicle including a vehicle engine that is used as a drive source of a compressor. The vehicle engine is stopped when the vehicle stops.
2. Description of Related Art
In recent years, in order to protect the environment and to reduce fuel consumption of a vehicle engine, a vehicle (e.g., economically running vehicle such as a hybrid vehicle) automatically stopping its engine at a time of a stoppage of the vehicle such as in waiting for a change of a traffic signal has been practically used, and hereafter, there is a tendency to increase the number of this-type vehicles. In an air conditioner for a vehicle, a compressor of a refrigerant cycle is generally driven by a vehicle engine. Therefore, in the economically running vehicle described above, the compressor is also stopped at every stoppage of the engine. Accordingly, in this case, a temperature of a cooling evaporator increases, and an air temperature blown into a passenger compartment increases, so that a cooling feeling for a passenger in the passenger compartment is damaged.
To overcome this problem, an air conditioner with a cold storage unit is provided. In this air conditioner, when operation of the vehicle engine (compressor) is stopped and cooling operation of an evaporator is stopped, air to be blown into the passenger compartment is cooled by using cold release operation of the cold storage unit. For example, in a cold-storage type air conditioner disclosed in JP-A-2000-313226, a cold storage tank having therein a cold storage material is disposed in parallel with an evaporator in a refrigerant flow direction, so that refrigerant decompressed by a decompression unit is circulated to the evaporator and the cold storage tank in parallel when the vehicle engine operates. Thus, the cold storage material is cooled while the vehicle engine operates, thereby performing cold storage (cold accumulation) in the cold storage material. When the operation of the compressor is stopped with the stop of the vehicle engine, liquid refrigerant in the cold storage tank is circulated to the evaporator. Accordingly, even when the operation of the compressor is stopped, a cooling capacity of the evaporator can be continuously obtained, so that the passenger compartment can be cooled.
However, in the air conditioner, since the cold storage tank and the evaporator are connected in parallel in the refrigerant flow direction, refrigerant decompressed by a decompression unit such as an expansion valve is divided to be supplied to the cold storage tank and to the evaporator. Therefore, in a large cooling-load condition such as in the summer, an amount of refrigerant circulated to the cooling evaporator becomes deficient, and cooling capacity of the evaporator becomes deficient. Further, after solidification of the cold storage material is completed, that is, after cold accumulation (cold storage) is completed, low-pressure refrigerant generally does not absorb heat from the cold storage material. Therefore, in this case, the low-pressure refrigerant passes through the cold storage tank while almost being not evaporated. Further, the low-pressure refrigerant from the cold storage tank joins with refrigerant at an outlet of the evaporator, and the joined refrigerant is sucked into the compressor.
Because the expansion valve controls a super-heating degree of the joined refrigerant, an opening degree of the expansion valve is also changed in accordance with low-dryness refrigerant from the cold storage tank. Therefore, the open degree of the expansion valve is adjusted excessively smaller with respect to the super-heating degree of refrigerant at the outlet of the evaporator. Thus, a refrigerant flow amount in the evaporator becomes smaller with respect to a cooling load of the evaporator, and cooling capacity of the evaporator cannot be sufficiently obtained. In order to accurately control the opening degree with respect to the cooling load, a solenoid valve is need in a refrigerant passage of the cold storage tank. In a case where the solenoid valve is provided, when the cooling performance is insufficient while the vehicle engine (compressor) operates, refrigerant circulation into the cold storage tank is stopped by closing the solenoid valve. Only when the cooling capacity of the evaporator is sufficient, the low-pressure refrigerant is circulated to the cold storage tank by opening the solenoid valve, and the cold storage of the cold storage material is performed. In this case, because the solenoid valve is required and a control mechanism for controlling the solenoid valve is also required, production cost of the air conditioner with a cold storage unit is increased. Further, the structure of the cold storage unit including the solenoid unit becomes complex, and the size of the cold storage unit is increased. Therefore, the cold storage unit is difficult to be mounted in the vehicle.
SUMMARY OF THE INVENTION
In view of the above-described problems, it is an object of the present invention to provide a vehicle air conditioner with a cold-storage heat exchanger, which effectively improves cooling capacity and cold-storage capacity while having a simple structure.
It is another object of the present invention to provide a vehicle air conditioner with a cold-storage heat exchanger, which improves condensation capacity of gas refrigerant in the cold-storage heat exchanger in a cold release mode.
It is -a further another object of the present invention to provide a vehicle air conditioner with a cold-storage heat exchanger, which improves heat-exchanging performance of an evaporator in the cold release mode when a compressor is stopped.
It is a further another object of the present invention to provide an air conditioner with a cold-storage heat exchanger, which can be readily mounted in a vehicle.
According to the present invention, in an air conditioner for a vehicle having an engine that is stopped when the vehicle stops, a compressor is driven by the engine, a high-pressure side heat exchanger is disposed to radiate heat of refrigerant discharged from the compressor, a decompression unit decompresses refrigerant flowing from the high-pressure side heat exchanger, and refrigerant from the decompression unit is evaporated in an evaporator so that air to be blown into a passenger compartment of the vehicle is cooled. Further, the air conditioner includes a cold-storage heat exchanger having therein a cold storage material for performing a cold storage operation where the cold storage material is cooled by refrigerant from the decompression unit, and a cold release operation where refrigerant circulates between the evaporator and the cold-storage heat exchanger so that gas refrigerant evaporated in the evaporator is cooled by cold release of the cold storage material in the cold-storage heat exchanger. In the air conditioner, the cold storage heat exchanger and the evaporator are connected in series in a refrigerant flow, such that the cold storage operation of the cold storage material is performed when the compressor operates, and the cold release operation of the cold storage material is performed when operation of the compressor is stopped with a stop of the engine. Because the cold-storage heat exchanger and the evaporator are disposed in series in the refrigerant flow, refrigerant always flows through the heat-storage heat exchanger and the evaporator by the operation of the compressor when the compressor operates. Therefore, the cooling capacity in the evaporator and the cold-storage capacity in the cold-storage heat exchanger can be
Aikawa Yasukazu
Kume Makoto
Suzuki Takahisa
Yamanaka Yasushi
Denso Corporation
Norman Marc
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