Refrigeration device with expansion valve coil temperature correction
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Solution Overview
Problem
Electronic expansion valves in refrigeration devices face durability issues due to coil temperature exceeding heat-resistant limits, leading to potential burning and reduced durability, and existing high-heat-resistant valve solutions increase production costs.
Innovation Solution
A refrigeration device with a control system that limits the operation of the electronic expansion valve's coil temperature by adjusting the control period and operation amount, estimating coil temperature based on energization and ambient conditions, and executing operation limit control during high-temperature conditions to prevent overheating without requiring special sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coil of the electronic expansion valve is energized at a high duty factor to adjust the valve position, then the valve operation performance is improved, but the coil temperature rises above the heat resistant temperature causing burning damages and reduced durability
Solution Approach 1:
The control device divides the energization control into multiple time periods, applying periodic action by controlling the coil in different time segments (first time period for initial positioning, second time period for fine adjustment) rather than continuous high-duty energization, thereby reducing peak temperature while maintaining operational effectiveness
Solution Approach 2:
The control device performs preliminary action by executing the first energization control in the first time period to achieve coarse valve positioning before applying the second energization control in the second time period for fine adjustment, allowing the system to reach the target position through a staged approach that limits overall heat generation
2Reliability
If a high-heat-resistant electronic expansion valve is employed to withstand high coil temperatures, then the durability is improved, but the component cost significantly increases
Solution Approach 1:
The control device changes the operational parameters (duty factor, energization timing, control duration) of the existing electronic expansion valve to keep coil temperature within the heat resistant range, allowing the use of standard-cost components rather than expensive high-heat-resistant variants while still achieving improved durability through controlled operation
3Speed
If the control period of the electronic expansion valve is shortened to improve response speed, then the operation responsiveness is improved, but the duty factor increases causing coil temperature to rise
Solution Approach 1:
The control device uses periodic action by implementing multi-stage energization control across different time periods, where the first energization control operates for a longer duration with lower duty factor and the second energization control operates for a shorter duration with higher duty factor, achieving both responsiveness and temperature management
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 effectively prevents coil temperature from exceeding heat-resistant limits, enhancing the durability of electronic expansion valves without the need for high-heat-resistant components, thus reducing production costs and maintaining system performance.
Implementation Method 1
the coil heats itself by the energization, and hence a temperature of the coil rises
Data Source
AI summary
There is disclosed a refrigeration device which is capable of inexpensively improving durability of an electronic expansion valve (an outdoor expansion valve) for use in a refrigerant circuit. A vehicle air conditioner 1 has a refrigerant circuit R including an outdoor expansion valve 6. The vehicle air conditioner includes a controller which controls energization to a coil of the outdoor expansion valve 6, and this controller executes operation limit control to limit an operation of the outdoor expansion valve 6 so that a temperature of the coil of the outdoor expansion valve 6 is not in excess of a predetermined value. The controller lengthens a control period of the outdoor expansion valve 6 and suppresses an operation amount of the outdoor expansion valve 6 within a predetermined limit value to limit a duty factor, in the operation limit control.