Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1999-08-06
2001-05-15
Tanner, Harry B. (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S228500, C062S236000, C062S323300
Reexamination Certificate
active
06230507
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a hybrid compressor used mainly for vehicle air-conditioning systems. More specifically, the present invention pertains to a hybrid compressor driven by two drive sources including an engine and an electric motor and its control method.
Generally, a vehicle air-conditioning system includes a refrigeration circuit, which has a compressor and an external circuit connected to the compressor. When the compressor is driven by a vehicle engine, refrigerant circulates in the refrigeration circuit, which cools a vehicle compartment. Typically, the compressor is connected to a single drive source (engine) through an electromagnetic clutch. When the cooling capacity of the refrigeration circuit becomes excessive as the cooling load on the refrigeration circuit decreases, the electromagnetic clutch is turned off, or disengaged, which temporarily stops the operation of the compressor. When the engine is stopped, the compressor is not operated, and the vehicle compartment is not cooled.
Japanese Unexamined Utility Model Publication No. 6-87678 describes a hybrid compressor driven by an engine and an electric motor. The hybrid compressor is driven by the electric motor when the engine is not running, which allows the vehicle passenger compartment to be cooled while the engine is stopped.
The hybrid compressor includes a compression mechanism having a drive shaft, an electric motor having an output shaft connected to the drive shaft, and an electromagnetic clutch connected to the output shaft. The engine is connected to the output shaft through the electromagnetic clutch. When the clutch is engaged while the engine is running, the power of the engine is transmitted to the drive shaft through the output shaft, which operates the compression mechanism. At this time, the output shaft of the electric motor rotates with the drive shaft. The rotation of the output shaft generates electromotive force in the electric motor, and a battery is charged by electric power based on the electromotive force. When the output shaft and the drive shaft are disconnected from the engine by disengaging the clutch while the engine is stopped, the compression mechanism can be driven by the motor, which is powered by the battery.
The compression mechanism of the hybrid compressor is a swash plate type variable displacement compressor. In the compression mechanism, the displacement is controlled by adjusting the inclination angle of the swash plate in accordance with the cooling load on the refrigeration circuit, so that the refrigeration circuit has the appropriate cooling capacity. However, the engine and the electric motor, which are different kinds of drive sources, have different characteristics. Therefore, the operating conditions of the compression mechanism when driven by the engine are different from those when it is driven by the electric motor. This makes it difficult to smoothly shift the drive source of the compression mechanism from the engine to the electric motor.
The motor is powered by a battery, which stores a limited amount of power. Therefore, when the compression mechanism is driven by the electric motor, it is necessary to limit the power consumption by efficiently operating the electric motor in addition to maintaining an appropriate capacity.
Japanese Unexamined Utility Model Publication No. 6-87678 does not attempt to solve this problem.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a hybrid compressor and its control method that enables smoother shifting of the drive source from the engine to the electric motor.
Another objective of the present invention is to provide a hybrid compressor and its control method that permits efficient operation of the compression mechanism by the electric motor.
To achieve the above objective, the present invention provides a control method for a hybrid compressor having a compression mechanism selectively driven by an engine and an electric motor. The compression mechanism includes a drive shaft selectively driven by the engine and the electric motor. The control method includes controlling the displacement per revolution of the drive shaft and the motor speed when the motor is driving the compression mechanism so that the hybrid compressor is operated efficiently.
The present invention further provides a hybrid compressor selectively driven by an engine and an electric motor. The hybrid compressor includes a compression mechanism having a drive shaft. The drive shaft is selectively driven by the engine and the motor. A controller controls the displacement per revolution of the drive shaft and the motor speed when the compression mechanism is being driven by the motor so that the compressor is operated efficiently.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
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patent: 2968961 (1961-01-01), McGregor
patent: 2983111 (1961-05-01), Miner et al.
patent: 4735058 (1988-04-01), Umezu et al.
patent: 4989414 (1991-02-01), Murayama et al.
patent: 5249429 (1993-10-01), Hanson
patent: 5685160 (1997-11-01), Abersfelder et al.
patent: 197 38 250A1 (1999-03-01), None
patent: 57-159976 (1982-10-01), None
patent: 5-187356 (1993-07-01), None
patent: 6-087678 (1994-12-01), None
Ban Takashi
Fujii Toshiro
Nakane Yoshiyuki
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Morgan & Finnegan , LLP
Tanner Harry B.
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