Method for controlling the power consumption of the compressor of a vehicle air-conditioning circuit, and related system
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Solution Overview
Problem
Motor vehicle air conditioning systems face challenges in reducing compressor consumption without exceeding a temperature difference of 5 Kelvin at the evaporator surface and ensuring the air blown by the evaporator remains below 15 °C, leading to inhomogeneous temperature distribution and inadequate cooling.
Innovation Solution
Simultaneous control of the temperature of the air blown by the evaporator and the temperature difference at the evaporator surface, combined with reduction of the degree of expansion of the expansion member, using sensors and an electric actuator to adjust the constraining force on movable expansion means, thereby reducing compressor displacement or rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the compressor displacement or rotational speed is reduced to lower compressor consumption, then energy efficiency improves, but the temperature difference at the evaporator surface exceeds 5 Kelvin and the air temperature exceeds 15°C
Solution Approach 1:
The invention changes the degree of expansion of the expansion member as a control parameter. By adjusting the expansion degree, the system modifies the refrigerant flow characteristics to maintain proper temperature distribution at the evaporator surface while allowing the compressor to operate at reduced consumption levels. This parameter change enables decoupling the compressor consumption from the temperature control requirements.
Solution Approach 2:
The system implements feedback control by continuously monitoring the temperature difference at the evaporator surface and the air temperature, then adjusting the expansion member's degree of expansion accordingly. This closed-loop feedback ensures that even when the compressor operates at reduced speed or displacement, the temperature parameters remain within acceptable limits through dynamic adjustment of the expansion characteristics.
2Use of energy by moving object
If the compressor consumption is significantly reduced, then energy efficiency improves, but the refrigerant circulation flow rate decreases causing inhomogeneous temperature distribution at the evaporator surface
Solution Approach 1:
The invention modifies the expansion parameter of the expansion member to compensate for the reduced refrigerant flow rate caused by lower compressor consumption. By optimizing the degree of expansion, the system ensures that the refrigerant is properly distributed across the evaporator surface, maintaining uniform temperature distribution despite the reduced overall flow rate.
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 effectively reduces compressor consumption while maintaining the temperature difference below 5 Kelvin and air temperature below 15 °C, ensuring efficient and uniform cooling without compromising comfort.
Implementation Method 1
reduction of the degree of expansion of the expansion member (9)
Implementation Method 2
the evaporator 11, which causes an inhomogeneity of the temperature at the surface of the evaporator 11
Data Source
Figure 1~2
Figure 3~4
AI summary
The method involves simultaneous checking of temperature of air blown by an evaporator and of a difference in temperature on a surface of the evaporator. An expansion rate of a relaxation element (9) is reduced as long as the temperature of the air blown by the evaporator is lower or equal to 15 degrees Celsius and the difference in temperature on the surface of the evaporator is lower than 5 Kelvin. A cubic capacity of a mechanical type compressor or number of revolutions of an electric type compressor is reduced. An independent claim is also included for a control system.