Vehicle AC Loop Pressure Control Using Pre-Start Fan Activation
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Solution Overview
Problem
The air conditioning loop in motor vehicles experiences pressure issues due to thermal inertia after engine shutdown, leading to increased refrigerant fluid pressure exceeding safety limits, which can cause compressor cycling and discomfort for users when trying to restart the air conditioning system.
Innovation Solution
A method that involves measuring the refrigerant fluid pressure and starting the motorized fan unit before the compressor to lower the pressure below safety levels, allowing safe operation of the air conditioning loop without additional equipment, thus enabling the system to start even after recent engine shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the air conditioning loop is started after engine shutdown, then the system should be available for use, but the refrigerant fluid pressure exceeds safety limits causing compressor cycling
Solution Approach 1:
The patent applies preliminary action by measuring the refrigerant fluid pressure before attempting to start the compressor. If the pressure exceeds the safety threshold Ps, the system prevents compressor startup and instead activates the gas cooler fan to reduce pressure. This preliminary pressure check and conditional fan activation resolves the contradiction by ensuring the system is ready for operation only when pressure conditions are safe, thereby maintaining both availability and reliability.
2Reliability
If the compressor is prevented from starting due to high pressure, then system safety is maintained, but user comfort is reduced due to cycling and engine jerking
Solution Approach 1:
The patent implements feedback by continuously monitoring refrigerant fluid pressure and using this information to control system operation. When pressure exceeds Ps, the system provides feedback to prevent compressor startup and activates the gas cooler fan. This closed-loop feedback mechanism maintains system safety while improving user comfort by eliminating the cycling and engine jerking that would otherwise occur, thereby resolving the contradiction between reliability and ease of operation.
3Reliability
If additional equipment is added to manage pressure, then system control is improved, but cost and size increase
Solution Approach 1:
The patent applies self-service by using existing system components (the gas cooler fan) to manage pressure conditions rather than adding dedicated pressure relief equipment. The control unit leverages the already-present fan to reduce pressure when needed, and the system uses its own operational states (fan running during AC operation) to accomplish pressure management. This approach improves pressure control capability while avoiding additional cost and size, resolving the contradiction between reliability and device complexity.
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 method ensures the air conditioning loop can be safely started, reducing downtime and improving thermal comfort for vehicle users by preventing compressor cycling and engine jerking, while maintaining the system's cost-effectiveness and size efficiency.
Implementation Method 1
the gas cooler is provided with at least one motor-fan unit... start the fan motor unit for a period of time D prior to starting the compressor, if the first pressure P1 of the refrigerant fluid is higher than the safety pressure Ps... makes it possible to lower the pressure of the refrigerant fluid inside the air conditioning circuit
Data Source
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AI summary
The method involves measuring pressure (P1) of supercritical refrigerant i.e. carbon dioxide, inside an air-conditioning loop. The pressure is compared with safety pressure (Ps), and a motor-ventilator set is started during preset time period (D) before starting of a compressor if the pressure is higher than the safety pressure, where a gas cooler cooperates with the motor-ventilator set. Starting of the motor-ventilator set is stopped during activation of a starter of an engine of a vehicle.