Electronic Expansion Valve Control Using Coil Signals for Mode Detection
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Solution Overview
Problem
Existing control systems for electronic expansion valves in refrigerant circuits are overly complex and costly due to the need for multiple output signals to manage various operating characteristics and modes, increasing the complexity of the unit control and overall air conditioning system.
Innovation Solution
A simplified control system that uses a single digital output signal from the unit control to an electronic expansion valve control, which receives compressor operation-related information and coil temperature signals to determine the system's mode of operation, reducing the complexity and cost by eliminating the need for additional signal generating capabilities in the unit control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple output signals are transmitted from unit control to expansion valve control to manage various operating characteristics, then the control capability is improved, but the device complexity and cost increase
Solution Approach 1:
The expansion valve control device is designed to perform multiple functions by processing different types of input signals (compressor operation signals, coil temperature signals, and mode determination) within a single integrated controller, eliminating the need for separate control circuits for each function and thereby reducing overall system complexity
Solution Approach 2:
The expansion valve control acts as an intermediary device that receives compressor operation-related information from the unit control and coil temperature signals from temperature sensing devices, processes these signals locally, and generates the appropriate expansion valve control signal without requiring the unit control to directly manage all control functions
2Adaptability or versatility
If multiple output signals are transmitted from unit control to expansion valve control, then the control capability is improved, but the manufacturing cost increases
Solution Approach 1:
The control logic for determining system mode and generating expansion valve control signals is extracted from the unit control and relocated to the expansion valve control device, reducing the manufacturing complexity and cost of the unit control while maintaining comprehensive control capability
Solution Approach 2:
The expansion valve control device performs self-determination of the system's mode of operation by processing coil temperature signals locally, eliminating the need for the unit control to generate and transmit separate mode determination signals, thereby reducing manufacturing costs
3Adaptability or versatility
If additional signal generating capability is incorporated in unit control, then the control functionality is improved, but the device complexity increases
Solution Approach 1:
The control system is segmented into distinct functional modules: the unit control handles high-level system management, the expansion valve control handles local signal processing and mode determination, and temperature sensing devices provide input data. This segmentation distributes complexity across multiple components rather than concentrating it in the unit control
Data Source
AI summary
A specially designed electronic expansion valve control system is provided for use with a refrigerant-based air conditioning circuit having a compressor, a condenser coil, an electronic expansion valve and an evaporator coil fluid coupled in series. The control system includes a unit control and an expansion valve control. The unit control is operative to receive compressor operation-related signal information and responsively generate at least one output signal representative of the received compressor operation-related signal information. The expansion valve control is operative to receive from the unit control only the at least one output signal, and to receive from one of the coils coil operation-related signal information, and to responsively output a control useable to control the expansion valve, the control signal being related in a predetermined manner to the signals received by the expansion valve control.