Ice Machine Refrigerant Charge Detection Using Freeze-Time Baselines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional compressor protection systems in refrigeration systems rely on discrete temperature and pressure sensors, which are costly, complex, and fail to accurately detect refrigerant charge levels due to variability in manufacturing and changes in refrigerant volume, leading to inefficiencies and potential damage from undercharge or overcharge conditions.
Innovation Solution
A diagnostic system that uses multiple sensors to generate signals indicative of motor current, discharge line temperature, and other parameters, processed by circuitry to determine a baseline freeze time and detect loss of charge conditions, adjusting thresholds and averaging values to provide accurate refrigerant charge monitoring without additional sensors for non-measured parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple discrete temperature and pressure sensors are placed at numerous locations within the system and compressor, then accurate indication of pressure or temperature is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies multi-functionality by using a single pressure sensor and single temperature sensor to perform multiple diagnostic functions. The pressure sensor detects both refrigerant charge levels and system pressure conditions, while the temperature sensor monitors both evaporator temperature and compressor discharge temperature. This allows one sensor to replace what would traditionally require multiple sensors, reducing system complexity while maintaining diagnostic accuracy
Solution Approach 2:
The system changes parameters by monitoring the relationship between pressure and temperature over time rather than relying on absolute threshold values. By tracking parameter trends and comparing actual readings against expected relationships (e.g., pressure-temperature saturation curves), the system can detect refrigerant charge issues and component failures without requiring multiple discrete sensors at various locations
2Reliability
If traditional temperature and pressure sensors are used, then system protection is provided, but accurate detection of refrigerant charge levels is failed due to manufacturing variability and refrigerant volume changes
Solution Approach 1:
The system implements feedback by continuously monitoring pressure and temperature readings and comparing them against expected relationships based on refrigerant properties and system operating conditions. The controller adjusts its diagnostic algorithms based on feedback from the sensors, tracking how pressure and temperature change together over time to determine refrigerant charge levels. This feedback mechanism allows accurate charge detection despite manufacturing variability and changing refrigerant volumes
Solution Approach 2:
The patent replaces traditional mechanical threshold-based protection systems with a diagnostic algorithm that uses computational analysis of sensor data. Instead of relying on fixed pressure or temperature thresholds that don't account for refrigerant charge variations, the system uses software-based diagnostics that calculate expected pressure-temperature relationships and compare actual readings against these dynamic expectations, thereby substituting mechanical simplicity with computational intelligence
3Object-affected harmful factors
If discrete switches are used to sense temperature and pressure parameters, then protection against high temperature or pressure is achieved, but system inefficiencies and false failures occur due to susceptibility to refrigerant volume changes
Solution Approach 1:
The system applies dynamics by transitioning from static threshold switches to dynamic diagnostic algorithms that continuously adapt to changing system conditions. The controller dynamically adjusts its interpretation of sensor readings based on operating conditions, refrigerant charge levels, and the relationship between multiple parameters over time. This dynamic approach allows the system to maintain protection while avoiding false failures that occur with fixed threshold switches when refrigerant volume changes
Data Source
AI summary
A system includes a compressor driven by a motor. A condenser receives working fluid from the compressor. An evaporator is in fluid communication with the condenser and the compressor. A first sensor produces a first signal, and a second sensor produces a second signal. A processing circuitry processes the first signal and the second signal to determine a new baseline freeze time. The processing circuitry determines the new baseline freeze time for a predetermined time following an installation event, a service event, or a power outage of the compressor.