Vehicle Air Conditioner Heating Startup Expansion Valve Control
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Solution Overview
Problem
Vehicle air conditioners using heat pump cycles face challenges in preventing vibrations and noises at the compressor during the start of a heating operation due to unstable refrigerant pressure and circulation resistance, which affects the compressor's operation and balance.
Innovation Solution
A control device is implemented to widen the opening degree of the expansion valve beyond the ordinary setting at the start of a heating operation, allowing easier refrigerant return and pressure increase, and then returns to the ordinary setting after a set time, stabilizing the compressor's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the expansion valve opening degree is increased at the start of heating operation, then the refrigerant circulation resistance is reduced and pressure increases promptly, but the valve opening degree must be changed from ordinary setting
Solution Approach 1:
The expansion valve opening degree is increased in advance before the compressor starts operating, allowing refrigerant to circulate and build pressure ahead of time. This preliminary action ensures that when the compressor starts, the refrigerant is already flowing smoothly, preventing vibrations and noises without requiring complex real-time control mechanisms.
Solution Approach 2:
The expansion valve opening degree is dynamically adjusted based on the operating phase: it is increased during the startup phase and then returned to the ordinary setting during normal operation. This dynamic adjustment optimizes refrigerant circulation at different stages while maintaining system simplicity through automated control.
2Power
If the compressor is started under low pressure conditions, then the compressor can start without high power demand, but the drive part rotation becomes unstable causing vibrations and noises
Solution Approach 1:
The system performs preliminary refrigerant circulation by increasing the expansion valve opening before compressor startup. This allows the refrigerant to establish stable flow patterns and pressure conditions in advance, so when the compressor starts at low power, the refrigerant is already positioned to provide stable lubrication and cooling to the drive part, preventing rotational instability.
Solution Approach 2:
The refrigerant acts as an intermediary medium that transfers momentum and stabilizes the drive part rotation. By ensuring refrigerant is already circulating through the system before compressor startup, the refrigerant provides a cushioning effect that prevents direct contact and vibration between the drive part and compressor housing during the vulnerable low-pressure startup phase.
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 reduces refrigerant circulation resistance, ensures prompt pressure increase within the compressor, and stabilizes the compressor's operation, effectively preventing vibrations and noises at the start of the heating operation.
Implementation Method 1
an expansion valve that reduces the pressure of the refrigerant which passes through the internal condenser and that expands the refrigerant
Implementation Method 2
an external heat exchanger that exchanges heat between the refrigerant which passes through the expansion valve and external air and that causes the refrigerant after the heat exchange with the external air to return to the compressor
Implementation Method 3
a compressor that compresses and discharges a suctioned refrigerant
Implementation Method 4
an internal condenser that releases heat of the refrigerant discharged from the compressor
Data Source
AI summary
A vehicle air conditioner includes a control device and a heating refrigerant circuit having: a compressor that compresses and discharges a suctioned refrigerant; an internal condenser that releases heat of the discharged refrigerant; an expansion valve that reduces a pressure of the refrigerant which passes through the internal condenser and that expands the refrigerant; and an external heat exchanger that exchanges heat between the refrigerant which passes through the expansion valve and external air and that causes the refrigerant after the heat exchange to return to the compressor. The opening degree of the expansion valve is controlled by the control device to be increased at a start of a heating operation to more than an ordinary opening degree during a heating operation to start the compressor, and after a set time elapses, to be caused to return to the ordinary opening degree during a heating operation.