Vehicle AC Compressor Valve Control for Stable Evaporator Cooling
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Solution Overview
Problem
Existing methods for controlling air conditioners in vehicles with swash-plate type variable capacity compressors face challenges in quickly and stably reaching target evaporator temperatures, often resulting in excessive undershoot or prolonged stabilization times due to fixed pressure control valve capacities, which can lead to passenger discomfort and noise issues.
Innovation Solution
The method involves variably controlling the target control value of the pressure control valve based on temperature deviations between the target and actual evaporator temperatures, employing a compulsive control mode initially to set the control value to maximum or minimum values depending on thermal load, followed by normal proportional-integral or proportional-integral-differential control to adjust coefficients according to thermal load needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If proportional-integral control is used to increase the control value of the pressure control valve when evaporator temperature is high, then the evaporator temperature can decrease quickly, but excessive undershoot occurs and stabilization takes considerable time
Solution Approach 1:
The patent applies dynamics by making the pressure control valve capacity variable rather than fixed. The valve capacity is dynamically adjusted based on operating conditions (high thermal load vs. low thermal load), allowing the system to optimize between rapid temperature decrease and stable convergence. This resolves the contradiction by adapting the control characteristics to the current operational state.
Solution Approach 2:
The patent changes the parameter of pressure control valve capacity from a fixed value to a variable parameter that depends on thermal load conditions. By switching between different capacity values (first capacity for high thermal load, second capacity for low thermal load), the system can achieve both rapid temperature response and stable convergence without excessive undershoot.
2Object-affected harmful factors
If the capacity of the pressure control valve is increased during operation, then the discharge capacity of the compressor increases slowly from minimum value, preventing operational shock and noise, but it takes a long time to reach target evaporator temperature
Solution Approach 1:
The patent makes the pressure control valve capacity dynamic by providing at least two different capacity values that can be switched based on thermal load conditions. This allows the system to rapidly increase discharge capacity when needed (reducing stabilization time) while still controlling noise and operational shock through appropriate capacity selection.
Solution Approach 2:
The patent changes the pressure control valve capacity parameter based on thermal load detection. When high thermal load is detected, a first (larger) capacity is used to quickly reach target temperature. When low thermal load is detected, a second (smaller) capacity is used to minimize noise and operational shock. This parameter switching resolves the time-noise contradiction.
3Device complexity
If the capacity of the pressure control valve is fixedly controlled, then the control system is simple, but it deteriorates convergence to reach target evaporator temperature and causes instability
Solution Approach 1:
The patent introduces dynamic capability to the pressure control valve by providing multiple capacity values that can be switched based on thermal load. This dynamic adjustment improves convergence stability and prevents oscillation, while the switching logic remains relatively simple (detect thermal load → select appropriate capacity), thus maintaining acceptable system complexity.
Solution Approach 2:
The patent changes the capacity parameter of the pressure control valve based on detected thermal load conditions. By switching between different capacity parameters (first capacity for high thermal load, second capacity for low thermal load), the system achieves reliable convergence without excessive complexity in the control architecture.
Data Source
AI summary
A vehicle air conditioner is controlled so a target control value of a pressure control valve controlling tilt angle of a swash-plate of a swash-plate type variable capacity compressor is variably controlled according to temperature deviation between target evaporator temperature and actual evaporator temperature, thereby controlling the compressor discharge capacity. Target heat discharge quantity is calculated. Target heat discharge quantity is calculated for high thermal load control or low thermal load control. The control value of the pressure control valve is compulsively controlled. Then the control value is normally controlled. The actual evaporator temperature can reach the target evaporator temperature at an initial operating stage, and temperature stability is secured.