Heat pump reversing valve control based on the valve reversing pressure and the system pressure
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Solution Overview
Problem
Heat pump systems face low-pressure protection issues and liquid entrainment during heating due to insufficient air supply and refrigerant reversal, especially at low ambient temperatures.
Innovation Solution
A control method that compares the reversing pressure difference of the four-way valve with the system pressure difference and adjusts the throttling element's opening degree to prevent low-pressure protection and liquid entrainment, by switching the four-way valve state and adjusting the throttling element's opening degree based on the comparison result, and further adjusts the throttling element's opening degree based on actual and target superheat degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the four-way valve is reversed to switch from refrigerating to heating mode, then the heating function is enabled, but liquid entrainment occurs in the compressor due to large amounts of refrigerant pouring into it
Solution Approach 1:
The patent applies preliminary action by adjusting the electronic expansion valve opening degree before the four-way valve switching is completed. The control method detects the switching state of the four-way valve and proactively adjusts the expansion valve to a smaller opening degree in advance, creating conditions to prevent liquid entrainment before it occurs. This preliminary adjustment ensures that when the valve switching completes and refrigerant flow changes, the compressor is already protected from liquid influx.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the four-way valve switching state and using this information to dynamically adjust the electronic expansion valve opening degree. The controller receives feedback signals about the valve state and automatically modifies the expansion valve position accordingly, creating a closed-loop control system that adapts to the changing system conditions during mode transitions.
2Temperature
If the air conditioning system starts heating at low ambient temperature, then heating operation is achieved, but the compressor suffers from low-pressure protection due to insufficient air supply
Solution Approach 1:
The patent applies preliminary action by adjusting the electronic expansion valve opening degree before the four-way valve switching is completed. The control method detects the switching state of the four-way valve and proactively adjusts the expansion valve to a smaller opening degree in advance, creating conditions to prevent low-pressure protection before it occurs. This preliminary adjustment ensures that when the valve switching completes and refrigerant flow changes, the compressor is already protected from insufficient air supply.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the four-way valve switching state and using this information to dynamically adjust the electronic expansion valve opening degree. The controller receives feedback signals about the valve state and automatically modifies the expansion valve position accordingly, creating a closed-loop control system that adapts to the changing system conditions during mode transitions.
3Speed
If the four-way valve is switched rapidly to change operating modes, then mode switching speed is improved, but system pressure instability increases causing operational issues
Solution Approach 1:
The patent implements feedback control by continuously monitoring the four-way valve switching state and using this information to dynamically adjust the electronic expansion valve opening degree. The controller receives feedback signals about the valve state and automatically modifies the expansion valve position accordingly, creating a closed-loop control system that adapts to the changing system conditions during mode transitions.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the opening degree parameter of the electronic expansion valve in response to four-way valve switching. The control method changes the expansion valve opening parameter based on detected valve states, transforming a fixed parameter into a dynamic one that adapts to different operating conditions and maintains system stability during transitions.
Data Source
AI summary
Provided are a control method of a heat pump system and a heat pump system. The heat pump system includes a throttling element and a four-way valve. The four-way valve has a first state in a case that the heat pump system operates for refrigerating and a second state in a case that the heat pump system operates for heating. The control method includes that: before the four-way valve is switched from the first state to the second state, A is compared with B, and switching of the state of the four-way valve is controlled and the opening degree of the throttling element is adjusted according to the comparison result, or switching of the state of the four-way valve is controlled according to the comparison result, or the opening degree of the throttling element is adjusted according to the comparison result.