Vehicle Heat Management Valve Control for Refrigerant Carryover
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Solution Overview
Problem
The existing refrigerant circuit devices for vehicles face issues with refrigerant flow and carryover when switching from cooling and heating mode to heating mode, due to response delays in the expansion valve, leading to potential compressor trouble.
Innovation Solution
A heat management device with a control system that adjusts the opening degree of the expansion valve to a smaller setting for a predetermined period when switching from a cooling and heating mode to a heating mode, thereby reducing refrigerant flow and increasing dryness, which suppresses carryover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opening degree of the expansion valve is reduced when switching from cooling and heating mode to heating mode, then the refrigerant flow into the chiller is reduced and carryover is suppressed, but response delay occurs and the refrigerant flow may temporarily be excessively great
Solution Approach 1:
The control device predicts the temperature change of the low-temperature side heat medium in advance before switching occurs. Based on this prediction, the expansion valve opening degree is adjusted proactively to prevent excessive refrigerant flow and carryover, rather than reactively responding after the temperature change occurs.
Solution Approach 2:
The control device continuously monitors the actual temperature of the low-temperature side heat medium and compares it with the predicted temperature. Based on this feedback, the expansion valve opening degree is dynamically adjusted to maintain optimal refrigerant flow and prevent carryover, ensuring both reliability and responsive control.
2Reliability
If the opening degree of the expansion valve is reduced to suppress carryover, then liquid phase refrigerant flow into the compressor is prevented, but heating performance may deteriorate due to reduced refrigerant flow
Solution Approach 1:
The control device predicts the temperature change of the low-temperature side heat medium before switching occurs and proactively adjusts the expansion valve opening degree to an appropriate level in advance. This prevents carryover while maintaining sufficient refrigerant flow to preserve heating performance, rather than overly restricting flow after the switch.
Solution Approach 2:
The control device continuously monitors the actual temperature of the low-temperature side heat medium and dynamically adjusts the expansion valve opening degree based on feedback. This ensures the opening degree is optimized to prevent carryover while maintaining adequate refrigerant flow for heating performance, balancing both requirements in real-time.
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 configuration effectively suppresses the refrigerant from entering the compressor in a liquid or gas-liquid phase, even with response delays, thereby preventing carryover and maintaining heating performance.
Implementation Method 1
a chiller that performs heat exchange between the refrigerant depressurizing by the expansion valve and a low-temperature side heat medium
Implementation Method 2
a heat exchanger that causes the low-temperature side heat medium to absorb heat of a battery, heat of a vehicle drive device, and heat of outside air
Implementation Method 3
a condenser for dissipating heat of the refrigerant discharged from the compressor, and an air conditioner that performs heating by utilizing heat dissipation at the condenser
Data Source
AI summary
When switching from the first mode in which there is a heating request for the air conditioner and there is a cooling request for the battery to the second mode in which there is a heating request for the air conditioner and there is no cooling request for the battery, the opening degree of the electric expansion valve of the refrigerant circuit is reduced for a predetermined period. Then, after a predetermined period of time has elapsed, the mode is switched from the first mode to the second mode.