EV Cooling Refrigerant Charge Detection via Compressor Superheat
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Solution Overview
Problem
Existing cooling systems in vehicles struggle to detect small losses of refrigerant, which can lead to reduced lubrication of the compressor and potential degradation, as traditional methods of measuring refrigerant pressure are only responsive to large losses.
Innovation Solution
A method is developed to estimate the superheating temperature of refrigerant at the compressor inlet based on pressure and temperature readings, and deactivate the compressor if this temperature exceeds a threshold, allowing for early detection of refrigerant loss and mitigating compressor degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional refrigerant pressure measurement methods are used, then the system structure remains simple, but the detection precision of refrigerant loss is insufficient and can only detect large losses
Solution Approach 1:
The patent uses superheating temperature as an intermediary parameter to indirectly detect refrigerant charge levels. Instead of directly measuring refrigerant mass or using complex sensors, the system measures temperature and pressure at the compressor inlet and calculates superheating temperature, which serves as a mediator to indicate refrigerant loss with higher precision while avoiding direct complex measurement systems
Solution Approach 2:
The patent replaces traditional mechanical pressure-only measurement systems with a thermodynamic calculation approach. By substituting direct mass flow sensors or complex pressure differential measurements with temperature and pressure-based superheating calculations, the system achieves higher detection precision using standard sensors and computational methods rather than complex mechanical measurement systems
2Reliability
If small refrigerant losses are detected early, then compressor degradation can be prevented, but the system requires more complex temperature and pressure monitoring
Solution Approach 1:
The patent performs preliminary detection of refrigerant charge issues by continuously monitoring superheating temperature before significant refrigerant loss occurs. This early warning system allows the control module to detect potential problems and alert operators before the refrigerant loss reaches levels that would cause compressor damage, enabling preventive maintenance actions
Solution Approach 2:
The system implements continuous feedback by monitoring superheating temperature at the compressor inlet and using this information to assess refrigerant charge status. The control module receives ongoing temperature and pressure data, calculates superheating in real-time, and provides continuous feedback on system health, enabling early detection and response to refrigerant loss without requiring complex additional hardware
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 approach enables the detection of smaller refrigerant losses, allowing for timely mitigating actions to maintain cooling and reduce the risk of compressor degradation, thereby providing a higher confidence level in refrigerant loss detection.
Implementation Method 1
The refrigerant may be compressed and condensed to a liquid before it is expanded in a chiller or an evaporator
Implementation Method 2
The refrigerant may be compressed and condensed to a liquid
Implementation Method 3
The evaporator may cool air that is passed over the evaporator
Implementation Method 4
The cooling system may include refrigerant and the refrigerant may be used to cool the battery and the passenger cabin
Data Source
AI summary
Methods and systems for assessing operation of a cooling system of an electric vehicle are described. In one example, a super heating temperature at an inlet of a compressor may be generated solely via a temperature sensor and a pressure sensor. The super heating temperature may be compared against a threshold super heating temperature to judge whether or not an amount of refrigerant in the cooling system is as expected.