Expansion valve position detection in refrigeration system
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Solution Overview
Problem
Refrigeration systems in display cases face challenges in accurately monitoring and controlling the position of expansion valves, especially during power failures, leading to inefficiencies and potential system malfunctions.
Innovation Solution
A controller system that determines and stores the position of an actuator, such as a stepper motor, by detecting current spikes, allowing for precise control and retrieval of the valve position, even in the event of a power failure, using a method that involves sending signals to the actuator and detecting current changes with a sensor to calibrate and monitor the valve's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion valve position is monitored using traditional methods, then the system can operate during normal conditions, but the valve position cannot be accurately retrieved after a power failure
Solution Approach 1:
The system performs preliminary action by continuously storing the expansion valve position in non-volatile memory during normal operation. This ensures that the position data is preserved and can be retrieved after a power failure, eliminating the information loss problem.
Solution Approach 2:
The patent creates a copy of the valve position data and stores it in non-volatile memory. This backup copy ensures that even if power is lost, the position information is preserved and can be recovered, solving the reliability issue.
2Measurement precision
If the controller continuously monitors actuator position, then accurate position data is available, but energy consumption increases
Solution Approach 1:
Instead of continuous monitoring, the system uses periodic action by detecting current spikes at specific intervals or events. The controller monitors actuator current and detects position changes based on characteristic current patterns, reducing energy consumption while maintaining measurement precision.
Solution Approach 2:
The actuator's own current consumption serves as the measurement signal. By analyzing the current spikes generated during actuator operation, the system derives position information without requiring separate sensors or continuous power-intensive monitoring circuits.
3Loss of information
If the system stores valve position data in volatile memory, then quick access is possible, but data is lost during power failure
Solution Approach 1:
The system performs preliminary action by implementing a power failure detection mechanism that triggers immediate data transfer from volatile to non-volatile memory. This preliminary protective action ensures data is preserved before power is completely lost, balancing speed and reliability.
Solution Approach 2:
The patent introduces an intermediary mechanism (power failure detection circuit and data transfer logic) that bridges volatile and non-volatile memory systems. This intermediary ensures seamless data preservation during power failures without requiring the entire system to be built with complex non-volatile memory.
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 solution enables efficient operation, reduces energy consumption, improves system performance, and ensures seamless recovery after power failures by accurately tracking and resetting the expansion valve's position, thus maintaining optimal refrigeration conditions.
Implementation Method 1
determining a position of the actuator; and storing the position of the actuator such that the position of the actuator is retrievable by the controller
Data Source
AI summary
A refrigerated display case having a housing defining a temperature controlled space and a refrigeration system coupled to the housing is provided. The refrigeration system is configured to be operable to affect a temperature of the temperature controlled space. The refrigeration system includes an actuator, a controller, and a sensor. The controller is configured to continuously update a stored position of the actuator based on measurement of an electric current provided to the actuator, retrieve the stored position after a power failure, and restart control based on the stored position of the actuator. The sensor is configured to communicate with the controller.