Vehicle air conditioner

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Solution Overview

Problem

In vehicle air conditioners, the rapid pressure drop in the accumulator during mode changes from heating to dehumidifying or cooling modes leads to refrigerant boiling and vaporization, causing liquid return to the compressor and noise, which impairs reliability and passenger comfort.

Innovation Solution

A vehicle air conditioner with a control device that manages valve positions and compressor revolutions to reduce the refrigerant flow into the accumulator, using a bypass pipe and auxiliary heating to prevent liquid return and noise, by gradually shifting from outdoor to indoor expansion valve operation and executing a refrigerant scavenging operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the outdoor expansion valve is fully opened to maximize refrigerant flow during heating mode, then heating efficiency is improved, but liquid refrigerant accumulates in the accumulator causing bumping and noise during mode transition

Engineering Contradiction:

Improveheating efficiencyVSAvoidbumping noise and liquid return

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The control device performs preliminary action by reducing the outdoor expansion valve position and maintaining high compressor revolutions for a predetermined period before the mode transition is complete. This anticipatory control prevents excessive liquid refrigerant from entering the accumulator during the transition from heating to dehumidifying or cooling modes, thereby avoiding bumping noise and liquid return to the compressor.

Inventive Principle:

Principle #10Preliminary action

2Speed

If the compressor stops quickly during mode change to respond rapidly to control commands, then responsiveness is improved, but pressure drop in the accumulator causes refrigerant to boil and vaporize intensely

Engineering Contradiction:

Improvemode transition speedVSAvoidcompressor reliability due to liquid compression

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The control device maintains high compressor revolutions for a predetermined period before actually changing to the dehumidifying or cooling mode. This preliminary maintenance of high revolutions prevents rapid pressure drop in the accumulator that would cause refrigerant boiling, while still achieving responsive mode transition. The compressor continues running at high speed to maintain pressure stability before the mode switch occurs.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the outdoor expansion valve is closed immediately during mode transition to prevent liquid flow, then liquid return is prevented, but refrigerant flow is restricted causing incomplete mode switching

Engineering Contradiction:

Improveprevention of liquid compressionVSAvoidmode transition completeness

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The control device dynamically adjusts the outdoor expansion valve position during the mode transition process rather than simply closing it immediately. The valve position is reduced for a predetermined period to limit liquid flow, then gradually opened as the mode transition progresses. This dynamic adjustment ensures both prevention of liquid return and complete mode switching, resolving the contradiction between reliability and productivity.

Inventive Principle:

Principle #15Dynamics

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 solution effectively reduces the impact of refrigerant boiling, prevents liquid compression, and minimizes noise, enhancing the reliability and comfort of the air conditioner by controlling refrigerant flow and pressure.

Implementation Method 1

let the refrigerant absorb heat in the outdoor heat exchanger

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Implementation Method 2

let the refrigerant radiate heat in the radiator

Methodology Applied

Scientific EffectHeat radiation: Thermal Radiation

Implementation Method 3

a compressor to compress and discharge a refrigerant

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 4

the refrigerant is once stored in this accumulator, thereby performing gas-liquid separation therein

Methodology Applied

Scientific EffectGas-liquid separation: Density Gradient

Implementation Method 5

the refrigerant is evaporated in the heat absorber

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 6

an outdoor expansion valve to decompress the refrigerant flowing out from the radiator

Methodology Applied

Scientific EffectDecompression: Depressurisation

Data Source

PatentUS10946723B2Vehicle air conditioner

Publication Date: 2021.03.16 SANDEN CORP

AI summary

A vehicle air conditioner which is capable of inhibiting liquid return to a compressor and generation of noise due to bumping in an accumulator. There are executed a heating mode to close a solenoid valve 17, open a solenoid valve 21, let a refrigerant radiate heat in a radiator 4, decompress the refrigerant through an outdoor expansion valve 6, let the refrigerant absorb heat in an outdoor heat exchanger 7, and send the refrigerant to an accumulator 12, and a dehumidifying and heating mode to open the solenoid valve 17, close the solenoid valve 21, decompress the refrigerant through an indoor expansion valve 8, let the refrigerant absorb heat in a heat absorber, and generate heat in an auxiliary heater 23. A valve position of the outdoor expansion valve 6 is reduced for a predetermined period of time before shifting from the heating mode to the dehumidifying and heating mode.