Control method for air conditioning systems for vehicles

Claim 1

A method for controlling an air conditioning system for a vehicle, including a compressor of a variable delivery type disposed to be driven by an engine installed in said vehicle, for compressing refrigerant, a condenser for cooling said refrigerant compressed by said compressor into a liquefied state, an expansion valve for regulating the flow rate of said liquefied refrigerant to a proper value corresponding to a thermal load on said air conditioning system, and an evaporator for evaporating said liquefied refrigerant supplied from said expansion valve, for cooling air to be discharged from said air conditioning system through heat exchange of said refrigerant being evaporated with said air, the method comprising the steps of: (a) setting a first control manner of controlling the delivery quantity of said compressor in response to operating conditions of said engine, in a manner irrespective of thermal load conditions of said air conditioning system, for preferential achievement of required driveability of said engine; (b) setting a second control manner of controlling the delivery quantity of said compressor in response to thermal load conditions of said air conditioning system, in a manner irrespective of operating conditions of said engine, for preferential achievement of required cooling capacity of said air conditioning system; (c) selecting one of said first control manner and said second control manner; and (d) controlling said air conditioning system in accordance with said selected one of said first and second control manners; said first control manner comprising the steps of: (i) detecting operating conditions of said engine; (ii) controlling the delivery quantity of said compressor to a predetermined minimum value when said engine is in a first predetermined operating condition wherein a high engine output is required; (iii) controlling the delivery quantity of said compressor to a predetermined maximum value when said engine is in a second predetermined operating condition wherein a low engine output suffices; and (iv) calculating a value of the delivery quantity of said compressor appropriate to a third operating condition of said engine other than said first and second predetermined operating conditions and required for achieving a desired value of the temperature of a compartment in said vehicle and controlling the delivery quantity of said compressor to said calculated value in a manner gradually varying the delivery quantity of said compressor toward said calculated value, when said engine is in said third operation condition.

Claim 2

A method for controlling an air conditioning system for a vehicle, including a compressor of a variable delivery type disposed to be driven by an engine installed in said vehicle, for compressing refrigerant, a condenser for cooling said refrigerant compressed by said compressor into a liquefied state, an expansion valve for regulating the flow rate of said liquefied refrigerant to a proper value corresponding to a thermal load on said air conditioning system, and an evaporator for evaporating said liquefied refrigerant supplied from said expansion valve, for cooling air to be discharged from said air conditioning system through heat exchange of said refrigerant being evaporated with said air, the method comprising the steps of: (a) setting a first control manner of controlling the delivery quantity of said compressor in response to operating conditions of said engine, in a manner irrespective of thermal load conditions of said air conditioning system, for preferential achievement of required driveability of said engine; (b) setting a second control manner of controlling the delivery quantity of said compressor in response to thermal load conditions of said air conditioning system, in a manner irrespective of operating conditions of said engine, for preferential achievement of required cooling capacity of said air conditioning system; (c) selecting one of said first control manner and said second control manner; and (d) controlling said air conditioning system in accordance with said selected one of said first and second control manners; said first control manner comprising the steps of: (i) detecting operating conditions of said engine; (ii) controlling the delivery quantity of said compressor to a predetermined minimum value when said engine is in a first predetermined operating condition wherein a high engine output is required; (iii) controlling the delivery quantity of said compressor to a predetermined maximum value when said engine is in a second predetermined operating condition wherein a low engine output suffices; and (iv) calculating a value of the delivery quantity of said compressor appropriate to a third operating condition of said engine other than said first and second predetermined operating conditions and required for achieving a desired value of the temperature of a compartment in said vehicle and controlling the delivery quantity of said compressor to said calculated value in a manner gradually varying the delivery quantity of said compressor toward said calculated value, when said engine is in said third operation condition.