Air-conditioning device and method for controlling air-conditioning device
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Solution Overview
Problem
In heat pump type vehicle air conditioning devices, performing a heat pump operation without using the outside heat exchanger leads to decreased compressor power due to low refrigerant pressure and increased torque due to high refrigerant pressure, causing inefficiencies.
Innovation Solution
The device includes a compressor, heating unit, accumulator, circulation and bypass flow paths, and expansion mechanisms, controlled by a unit to adjust the proportion of gas and liquid refrigerant to stabilize compressor pressure and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat pump operation is performed without using the outside heat exchanger, then frost formation on the outside heat exchanger is prevented, but the compressor power decreases due to low refrigerant pressure
Solution Approach 1:
The accumulator serves as an intermediary component between the compression and heating units. It receives refrigerant from the compression unit, separates liquid components, and supplies regulated refrigerant to the heating unit. This intermediary function allows the system to operate without the outside heat exchanger while maintaining proper refrigerant pressure and composition for compressor performance.
Solution Approach 2:
The control unit dynamically adjusts the opening degrees of the first and second expansion mechanisms to change the proportion of gas and liquid refrigerant in the inflow to the accumulator. By controlling the gas refrigerant proportion to be larger than the outflow gas proportion, the system maintains optimal refrigerant pressure and density for compressor operation during frost prevention mode.
2Reliability
If heat pump operation is performed without using the outside heat exchanger, then frost formation on the outside heat exchanger is prevented, but the torque necessary for operating the compressor increases due to high refrigerant pressure
Solution Approach 1:
The control unit adjusts the opening degrees of the expansion mechanisms to control the liquid refrigerant proportion in the inflow to the accumulator. By maintaining the liquid refrigerant proportion in inflow larger than that in outflow, the system regulates refrigerant density and pressure characteristics, optimizing the torque requirements for compressor operation during frost prevention mode.
Solution Approach 2:
The control unit continuously monitors and adjusts the expansion mechanism opening degrees based on the refrigerant pressure conditions. This feedback control ensures that the refrigerant proportion and pressure are maintained within optimal ranges, preventing excessive torque requirements while maintaining frost prevention operation.
3Power
If the proportion of gas refrigerant in inflow to the accumulator is increased, then compressor power is maintained, but the proportion of gas refrigerant in outflow increases causing pressure instability
Solution Approach 1:
Instead of trying to prevent gas refrigerant from entering the accumulator, the system intentionally allows more gas refrigerant in the inflow than in the outflow. The accumulator acts as a buffer that separates liquid components while managing gas refrigerant proportions, inverting the conventional approach of trying to eliminate gas phase refrigerant entirely.
Solution Approach 2:
The control unit dynamically adjusts the opening degrees of the expansion mechanisms to control the refrigerant composition. By managing the gas refrigerant proportion difference between inflow and outflow, the system maintains both compressor power and composition stability through active parameter control.
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 stabilizes compressor power and torque by adjusting refrigerant proportions, preventing power loss and torque increase, ensuring efficient operation.
Implementation Method 1
a first expansion mechanism that is disposed at the circulation flow path and that expands the refrigerant flowing out from the heating unit, a second expansion mechanism that is disposed at the bypass flow path and that expands the refrigerant discharged from the compressor
Implementation Method 2
an accumulator that separates a liquid component in the refrigerant sucked by the compressor
Data Source
AI summary
Provided is a vehicle air-conditioning device comprising: a circulation channel that guides a refrigerant that has passed through a heating until towards an accumulator; a bypass channel that guides the refrigerant towards the accumulator without passing through the heating unit; and a control unit that controls the opening amount of an expansion valve provided on the circulation channel and an expansion valve provided on the bypass channel, wherein the control unit controls the opening amount of the expansion valve and the expansion valve so that the proportion of gas refrigerant in inflow refrigerant flowing into the accumulator is greater than the proportion of gas refrigerant in outflow refrigerant flowing out of the accumulator when the pressure of the refrigerant drawn in by a compressor is less than a predetermined pressure, and that the proportion of liquid refrigerant in the inflow refrigerant is greater than the proportion of liquid refrigerant in the outflow refrigerant when the pressure of the refrigerant drawn in by the compressor is greater than the predetermined pressure.