Compressor Control for Cold-Start Vehicle A/C
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Solution Overview
Problem
The existing system for controlling a compressor in a cold-start vehicle often results in frequent A/C cuts due to insufficient brake negative pressure, leading to poor cooling performance and customer complaints, especially in cold-start conditions, as it relies on calculated intake manifold pressure rather than actual brake booster pressure, causing incorrect A/C operation.
Innovation Solution
A system that includes an engine controller, operation information detector, compressor, and pressure regulator, which adjusts the compressor's A/C duty based on detected engine negative pressure and vehicle conditions, reducing torque requirements and entering a negative pressure recovery mode to prevent repeated A/C cycles, thereby maintaining minimum compressor operation and ensuring dehumidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air conditioner operation is stopped when intake manifold negative pressure drops below a certain value, then the brake negative pressure recovery is improved, but the cooling performance and dehumidification capability deteriorate due to frequent A/C cuts during cold-start
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the A/C duty cycle based on engine operating conditions. During cold-start, the controller reduces compressor duty to minimum when intake manifold negative pressure is insufficient, preventing frequent A/C cuts while maintaining brake pressure. The system monitors coolant temperature, vehicle speed, and negative pressure to modulate compressor operation, transforming the fixed A/C cut logic into a variable duty cycle control that adapts to changing parameters.
Solution Approach 2:
The patent implements dynamics by transitioning from static A/C cut logic to dynamic compressor duty control. The system continuously adjusts compressor operation based on real-time conditions including coolant temperature, vehicle speed, accelerator pedal position, and intake manifold negative pressure. This dynamic adjustment prevents frequent on/off cycling during cold-start while ensuring A/C operation stops when brake pressure critically drops, resolving the contradiction between reliability and performance.
2Reliability
If the A/C duty is reduced to minimum operation during cold-start with insufficient negative pressure, then the frequency of A/C cuts is reduced, but the cooling capacity is limited
Solution Approach 1:
The patent applies partial action by operating the compressor at minimum duty during cold-start conditions with insufficient negative pressure. Instead of complete A/C cut, the system maintains partial compressor operation that provides sufficient dehumidification and prevents windshield moisture while consuming minimal engine power. This partial operation continues until negative pressure recovers or cold-start condition ends, then transitions to normal duty cycle control.
3Use of energy by moving object
If the compressor operation is repeatedly stopped and started during cold-start, then the engine load is reduced, but the customer satisfaction decreases due to windshield moisture generation
Solution Approach 1:
The patent applies preliminary action by proactively reducing compressor duty to minimum during cold-start when negative pressure is insufficient, before the condition deteriorates to require complete A/C cut. This preventive measure ensures continuous dehumidification operation, preventing windshield moisture accumulation from the outset. The system monitors coolant temperature and negative pressure to trigger early duty reduction, eliminating the need for repeated stop-start cycles that cause moisture problems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the frequency of A/C cuts, improves dehumidification performance, and enhances customer satisfaction by accurately managing compressor duty based on actual engine conditions, eliminating the need for a brake booster sensor and optimizing the trade-off between cooling and brake performance.
Implementation Method 1
a compressor that generates pressure through a piston operation of a cylinder utilizing the power of the engine during operation of the air conditioner (A/C)
Implementation Method 2
the compressor may include a pressure regulator for regulating an operation rate of the piston by changing the angle of the swash plate in accordance with the A/C duty control signal applied from the controller
Data Source
AI summary
A system for controlling a compressor may include an engine controller that controls a fuel injection amount corresponding to an engine load and an opening amount of a throttle by reflecting a required torque required for an air conditioner (A/C), an operation information detector for detecting operation information according to driving state of the vehicle, a compressor that generates pressure during operation of the A/C, an air conditioner relay which is turned on when the air conditioner operates and is turned off when the A/C is stopped, and a controller which determines an engine negative pressure of an intake manifold, and when the cooling water temperature is lower than the predetermined temperature and the intake manifold pressure is lower than the first threshold value, a cold-start intake manifold negative pressure insufficient event is generated to reduce the A/C duty in accordance with the entry into a negative pressure recovery mode.