Vehicle AC Compressor Protection via Virtual Discharge Pressure Sensing
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Solution Overview
Problem
Existing air conditioning systems in vehicles face damage due to excessive compressor operation or refrigerant deficits, with the use of specific sensors increasing manufacturing costs.
Innovation Solution
A device that estimates refrigerant discharge pressure using predetermined vehicle and air conditioning system information, and includes a dual pressure switch and operation controller to determine whether to drive the compressor, eliminating the need for a specific sensor by using a pressure estimator and an estimation map corrector to adjust pressure estimates based on actual operation pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor is used to measure refrigerant discharge pressure, then the air conditioning system can prevent damage from excessive compressor operation, but the manufacturing cost of the vehicle increases
Solution Approach 1:
The patent creates a virtual copy of the pressure sensor function through software estimation. The pressure estimator calculates discharge pressure based on refrigerant mass flow rate and other operational parameters, replicating the sensor's protective function without physical hardware. This resolves the contradiction by providing reliable pressure monitoring while eliminating sensor manufacturing costs.
Solution Approach 2:
The patent replaces the mechanical sensor system with a computational estimation system. Instead of using physical sensors to detect pressure, the system uses algorithms that process operational data (refrigerant mass flow rate, compressor speed, etc.) to estimate discharge pressure. This substitution eliminates the need for expensive sensors while maintaining the protective function.
2Ease of manufacture
If no sensor is used to reduce manufacturing cost, then the vehicle production cost decreases, but the air conditioning system may suffer damage from excessive compressor operation
Solution Approach 1:
The system uses its own operational data (refrigerant mass flow rate, compressor speed, pressure differential across expansion device) to self-monitor and estimate discharge pressure. This self-service approach eliminates the need for external sensors while maintaining protective capabilities, resolving the contradiction between cost reduction and reliability.
Solution Approach 2:
The pressure estimator continuously receives feedback from operational parameters and adjusts its discharge pressure estimation accordingly. The system monitors refrigerant mass flow rate, compressor speed, and pressure differential across the expansion device, using this feedback to maintain accurate pressure estimation for compressor protection without requiring physical sensors.
3Ease of manufacture
If a pressure estimator is used instead of a sensor, then manufacturing cost is reduced, but the precision of pressure measurement may be compromised
Solution Approach 1:
The patent changes the approach from direct pressure measurement to estimation based on multiple related parameters. By calculating discharge pressure from refrigerant mass flow rate, compressor speed, and pressure differential across the expansion device, the system achieves sufficient accuracy for protective purposes without the cost of precision sensors. The estimation uses the relationship P2 = P1 + ΔP where P1 is suction pressure and ΔP is pressure differential.
Data Source
AI summary
A device for protecting an air conditioning system of a vehicle is configured to prevent damage to an air conditioning system due to excessive operation of a compressor or a deficit of a refrigerant by accurately determining whether to operate the compressor even without using a specific sensor that causes an increase in the manufacturing cost of a vehicle.