Vehicle Heat Pump Pressure Equalization for Quiet Mode Switching
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Solution Overview
Problem
Conventional heat pump systems for vehicles experience noise and vibration due to refrigerant pressure differences when switching between heat pump and air conditioning modes, and there is a delay in supplying cold air when changing modes.
Innovation Solution
A heat pump system with a control unit that adjusts the opening degree of the first expansion valve by delaying its opening for a predetermined period when switching from heat pump mode to air conditioning mode, using pressure sensors to calculate a target pressure difference and gradually opening the valve to achieve pressure equilibrium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the first expansion valve is opened immediately when switching from heat pump mode to air conditioning mode, then cold air can be supplied quickly, but noise and vibration occur due to refrigerant pressure difference
Solution Approach 1:
The control unit delays opening the first expansion valve for a predetermined period after mode switching. This preliminary delay allows the refrigerant pressure difference to decrease before the valve opens, preventing noise and vibration while still enabling relatively quick cold air supply
Solution Approach 2:
The control unit monitors the operation mode and uses this feedback to control the timing of the first expansion valve opening. By detecting the mode switch signal, the control unit implements the predetermined delay period before opening the valve, thereby coordinating valve operation with system pressure conditions
2Object-affected harmful factors
If the first expansion valve is delayed for opening when switching modes, then noise and vibration are reduced, but there is a delay in supplying cold air
Solution Approach 1:
The delay period is set to a predetermined partial duration that is sufficient to reduce noise and vibration but not excessively long. This partial delay balances the need to reduce harmful factors while minimizing the loss of time for cold air supply
Solution Approach 2:
The control unit changes the operational parameters of the first expansion valve by controlling its opening timing. By adjusting the delay period parameter, the system optimizes the balance between reducing noise/vibration and maintaining acceptable cold air supply speed
3Stability of the object's composition
If the compressor continues running during mode switching, then refrigerant circulation is maintained, but pressure difference causes noise and vibration
Solution Approach 1:
The control unit implements a preliminary delay period before opening the first expansion valve after mode switching. During this delay, the compressor continues running to maintain refrigerant circulation stability, while the delayed valve opening prevents the pressure difference from causing noise and vibration
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
The system effectively reduces noise and vibration, rapidly supplies cold air upon mode change, and minimizes the delay in achieving pressure equilibrium.
Implementation Method 1
an indoor heat exchanger (102) installed within an air conditioning case (114) to heat-exchange the refrigerant discharged from the compressor (101) with air passing through the indoor heat exchanger (102)
Implementation Method 2
an evaporator (113) installed within the air conditioning case (114) to heat-exchange the refrigerant with air passing through the evaporator (113)
Implementation Method 3
a first expansion valve (104) to expand the refrigerant passing through the indoor heat exchanger (102)
Data Source
AI summary
Heat pump system for a vehicle and method for controlling same, which can, during mode changing between air heating and conditioning, prevent noise and vibration due to a pressure difference between refrigerants and reduce delay time. Heat pump system comprises a compressor compressing and discharging refrigerant, an indoor heat exchanger in air conditioning case, causing the refrigerant discharge from the compressor to heat the air, a first expansion valve for selectively expanding the refrigerant passed through the indoor heat exchanger, an evaporator in air conditioning case, enabling refrigerant to exchange heat with air evaporating refrigerant, and a controller for controlling the opening degree of the first expansion valve during mode changing between air heating and conditioning, wherein the controller turns off the compressor and gradually opens the first expansion valve to increase the opening degree when the mode is changed from the heat pump mode to the air conditioning mode.