초록 ▼

An improved control method for an electronically controlled variable displacement refrigerant compressor, where the control has normal and high speed displacement control modes, with smooth transitions between such control modes. The displacement control mechanism is in the form of a solenoid valve,

An improved control method for an electronically controlled variable displacement refrigerant compressor, where the control has normal and high speed displacement control modes, with smooth transitions between such control modes. The displacement control mechanism is in the form of a solenoid valve, and the valve is pulse-width-modulated (PWM) at a variable duty cycle to regulate displacement of the compressor. When the compressor is operating in a normal speed range, a first control mode determines a normal PWM duty cycle to satisfy cooling demand; when the compressor is operating in a high speed range, a second control mode determines an alternate PWM duty cycle based on compressor speed. The solenoid valve is operated in accordance with the duty cycle corresponding to the lower displacement. A smooth transition from the normal control mode to the high speed control mode is achieved by scheduling the alternate duty cycle as a function of compressor speed. Once in the high speed control mode, the parameters of the first control mode are adjusted so that the normal duty cycle matches the alternate duty cycle. This ensures a smooth transition from the high speed control mode to the normal control mode when the compressor speed falls back into the normal speed range.

대표청구항 ▼

[ We claim:] [1.] A method of operation for an engine driven refrigerant compressor of an automotive air conditioning system, the compressor having a displacement that is controlled in accordance with an electrical displacement control signal developed in response to a cooling demand signal, the met

[ We claim:] [1.] A method of operation for an engine driven refrigerant compressor of an automotive air conditioning system, the compressor having a displacement that is controlled in accordance with an electrical displacement control signal developed in response to a cooling demand signal, the method comprising the steps of:detecting a driven speed of the compressor;generating a feedback signal indicative of a cooling effect actually produced by said air conditioning system;developing the displacement control signal in accordance with a first control mode when the detected compressor speed is within a normal speed range, the first control mode being effective to set the displacement control signal at a normal control value selected to bring the feedback signal into correspondence with the cooling demand signal; anddeveloping the displacement control signal in accordance with a second control mode when the detected compressor speed is in a high speed range above said normal speed range, the second control mode being effective to (1) set the displacement control signal at an alternate value based on the detected compressor speed without regard to said cooling demand signal, and (2) modify a control parameter of said first control mode so that said normal control value matches said alternate value.