Scroll Compressor Unloading Detection Using Discharge Temperature
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Solution Overview
Problem
Scroll compressors in climate-control systems are prone to unintentional unloading, leading to increased noise, efficiency decreases, and premature wear due to axial and radial unloading, which existing technologies fail to effectively detect and remediate.
Innovation Solution
A system with a controller that determines a predicted discharge temperature and compares it with the actual discharge temperature, detecting unloading by analyzing the difference and compressor speed, and performs remedial actions such as adjusting the condenser fan operation or increasing compressor speed to mitigate unloading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scroll compressor operates under certain conditions, then compression function is achieved, but unintentional unloading occurs causing increased noise and decreased efficiency
Solution Approach 1:
The system continuously monitors discharge temperature and compares it with a predicted temperature calculated from evaporating and condensing temperatures. When the actual discharge temperature deviates from the predicted value beyond a threshold, the system detects unloading and triggers remedial actions such as adjusting condenser fan speed or compressor speed to restore proper compression function
Solution Approach 2:
The patent replaces direct mechanical monitoring of scroll contact with a thermal field-based detection system. Instead of using mechanical sensors to detect scroll separation, the system uses temperature measurement and comparison to indirectly detect unloading conditions, enabling non-intrusive monitoring without additional mechanical components
2Measurement precision
If scroll compression mechanism is monitored for unloading, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The system uses discharge temperature as an intermediary parameter to detect scroll unloading. Rather than directly monitoring scroll contact or mechanical separation, the system measures temperature (a readily available parameter in refrigeration systems) and uses it as an indirect indicator of compression effectiveness, simplifying the detection mechanism while maintaining accuracy
Solution Approach 2:
The temperature sensor serves multiple functions: it monitors discharge temperature for unloading detection, provides data for calculating predicted temperature, and enables the controller to diagnose compression issues. This multi-functional use of existing sensors reduces the need for additional specialized detection devices
3Productivity
If remedial actions are taken to stop unloading, then compression efficiency is maintained, but operational interruptions occur
Solution Approach 1:
The system dynamically adjusts operational parameters based on real-time temperature comparison. When unloading is detected, the controller modulates condenser fan speed or compressor speed to restore proper compression. This dynamic adjustment allows the system to maintain efficiency while minimizing interruptions, as the remedial actions are proportional and adaptive rather than binary on/off responses
Data Source
AI summary
Systems and methods for scroll unloading detection are provided and include a scroll compressor having a scroll compression mechanism. A controller determines a predicted discharge temperature of the scroll compressor, receives an actual discharge temperature of the scroll compressor, and compares the predicted discharge temperature with the actual discharge temperature. The controller also compares a speed of the scroll compressor with a speed threshold and detects unloading of the scroll compression mechanism based on the comparison of the predicted discharge temperature with the actual discharge temperature and based on the comparison of the speed of the scroll compressor with the speed threshold. The controller performs at least one of generating an alert and a remediating action in response to detecting the unloading of the scroll compression mechanism.