Vehicle Refrigerant Charging Using Efficiency Feedback
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Solution Overview
Problem
Conventional refrigerant charging systems for vehicles are inaccurate and vibration-sensitive, particularly with high-pressure carbon dioxide refrigerants, leading to inefficiencies and potential system damage due to insufficient or excessive refrigerant levels, and manufacturers' specifications often cause confusion with varying tolerance ranges.
Innovation Solution
A system and method that uses a controller, refrigerant source, control valve, and efficiency sensor to input a predetermined amount of refrigerant, measure system efficiency, and adjust the charge in discrete bursts to achieve optimal refrigerant levels, eliminating the need for high-resolution scales and ensuring accurate charging based on efficiency rather than weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load cell is used to measure refrigerant amount by weight, then the refrigerant charge can be quantified, but the measurement becomes sensitive to vibration and loses sensitivity when tank weight increases
Solution Approach 1:
The patent replaces the mechanical load cell measurement system with a refrigerant expansion-based measurement system. Instead of measuring weight mechanically, the system measures refrigerant expansion volume in a calibrated chamber, which is then converted to refrigerant mass using known density relationships. This substitution eliminates vibration sensitivity and tank weight interference while maintaining measurement precision.
Solution Approach 2:
The patent introduces a refrigerant expansion chamber as an intermediary measurement device. The refrigerant expands from the high-pressure storage tank into this calibrated chamber, and the expansion volume serves as the measurement parameter. This intermediary approach decouples the measurement from the original tank weight and vibration issues, providing accurate refrigerant quantity determination.
2Quantity of substance
If carbon dioxide is used as refrigerant with high storage pressure, then refrigerant density and charging efficiency improve, but tank weight increases requiring thicker walls
Solution Approach 1:
The patent replaces direct weight-based measurement with volume-based expansion measurement. By measuring how much refrigerant expands into a calibrated chamber rather than weighing the entire heavy tank, the system achieves accurate refrigerant quantity measurement without being affected by the increased tank weight from thicker CO2-compatible walls.
3Adaptability or versatility
If manufacturer specifications with tolerance ranges are used, then flexibility is provided, but confusion arises from varying tolerance ranges across manufacturers
Solution Approach 1:
The patent implements a feedback-based charging system that uses an efficiency sensor to monitor refrigeration system performance in real-time. The controller adjusts refrigerant charging based on actual system efficiency measurements, providing objective feedback that eliminates confusion from varying manufacturer specifications. This feedback mechanism automatically determines the optimal charge point within or near manufacturer recommendations without requiring interpretation of tolerance ranges.
Solution Approach 2:
The system enables self-adjusting refrigerant charging by using the refrigeration system's own efficiency sensor and controller to determine when optimal charging has been achieved. Rather than relying on external manufacturer specifications with varying tolerances, the system serves itself by autonomously identifying the optimal charge point through performance monitoring.
Data Source
AI summary
A charging system for charging a refrigeration system of a vehicle includes a controller, a refrigerant source, at least one line fluidly connecting the refrigerant source to the refrigeration system; a control valve disposed to control flow of the refrigerant from the refrigerant source to the refrigeration system, and an efficiency sensor for measuring the efficiency of the refrigeration system. The controller operates to cause the charging system to input into the refrigeration system a predetermined amount of refrigerant less than a recommended refrigerant charge amount; measure a baseline efficiency of the refrigeration system, input a supplemental amount of refrigerant into the refrigeration system, measure an adjusted efficiency of the refrigeration system, and compare the measured adjusted efficiency to the baseline efficiency using the controller.