Vehicle Air Conditioner Evaporator Temperature Control
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Solution Overview
Problem
Conventional air conditioner control methods for vehicles experience undershoot and delayed temperature convergence in the evaporator, leading to discomfort for passengers, especially when the outdoor temperature is low or the target evaporator temperature is high, due to sharp initial temperature drops and extended convergence times.
Innovation Solution
A method for controlling the air conditioner that calculates a discharge capacity control value for a variable capacity swash type compressor using proportional-integral control, adjusting the compressor's discharge capacity before shutdown and implementing maximum capacity control when the evaporator temperature does not reach the target, and performing proportional-integral control based on the lapse time after restart to prevent undershoot and ensure quick temperature convergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If maximum capacity control is performed at initial operation to quickly reach target temperature, then response time is improved, but undershoot occurs causing temperature to drop below target
Solution Approach 1:
The control method stores the discharge capacity control value from directly before A/C shutdown and applies it at the next startup. This preliminary preparation of control parameters prevents the need for aggressive maximum capacity control, allowing the system to reach target temperature without undershoot while maintaining reasonable response time.
Solution Approach 2:
The system uses proportional-integral control with feedback from the evaporator temperature sensor to continuously adjust the discharge capacity control value. This feedback mechanism ensures precise temperature control by comparing actual temperature with target temperature and adjusting compressor output accordingly, preventing both undershoot and excessive response delay.
2Manufacturing precision
If proportional-integral control is used to prevent undershoot, then temperature control precision is improved, but response time increases due to delayed temperature convergence
Solution Approach 1:
By storing and reusing the discharge capacity control value from before shutdown, the system starts each A/C cycle with optimized control parameters already prepared. This eliminates the need for conservative proportional-integral control from a cold start, achieving both precision and fast response simultaneously.
Solution Approach 2:
The control method dynamically changes the discharge capacity control value based on operating conditions (lapse time since shutdown, target temperature, outdoor temperature). By adjusting these parameters adaptively rather than using fixed proportional-integral gains, the system achieves precise temperature control without excessive response delay.
3Manufacturing precision
If discharge capacity is reduced to avoid undershoot in challenging conditions, then temperature control precision is improved, but productivity of cooling system decreases
Solution Approach 1:
The system dynamically adjusts the discharge capacity control value based on real-time conditions including lapse time since shutdown, target evaporator temperature, and outdoor temperature. This dynamic control allows maximum cooling capacity when needed while preventing undershoot, optimizing both productivity and precision adaptively throughout operation.
Solution Approach 2:
By changing the discharge capacity control value as a variable parameter rather than maintaining reduced capacity, the system achieves precise temperature control without sacrificing cooling efficiency. The control value is optimized for each operating condition, ensuring maximum productivity when high cooling demand exists while preventing undershoot through adaptive parameter adjustment.
Data Source
AI summary
The present invention relates to a method for controlling a vehicle air-conditioner, which can prevent undershoot of an evaporator by performing a maximum capacity control or controlling an discharge capacity of a compressor through the outputting of an discharge capacity control value of the compressor directly before the stop of the air conditioner, and can improve the pleasant feelings of the passengers by preventing delay of response, which converges into the target temperature of the evaporator due to the delay of the decrease of the temperature of the evaporator.