Vehicle Air Conditioning Compressor Temperature Control
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Solution Overview
Problem
Existing air conditioning loop systems with subcritical refrigerant fluids face challenges in controlling compressor discharge temperature, particularly when internal heat exchangers lead to excessive refrigerant overheating, requiring either risky assumptions or costly temperature sensors for effective management.
Innovation Solution
A method that calculates and estimates various parameters such as compressor inlet and outlet pressures, vehicle speed, and refrigerant flow to control the compressor signal without relying on temperature sensors, using existing sensors like pressure sensors and fan motor voltage to manage compressor operation and evaporator temperature setpoints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an internal heat exchanger is added to the air conditioning loop, then the cooling power and energy efficiency are improved, but the refrigerant fluid overheating at the compressor outlet becomes excessive
Solution Approach 1:
The patent changes the control parameters from direct temperature measurement to indirect parameter estimation using pressure measurements and thermodynamic models. By estimating temperatures from pressure data and system operating conditions, the method maintains effective temperature control without requiring additional temperature sensors, thus resolving the contradiction between energy efficiency improvement and temperature management.
Solution Approach 2:
The patent introduces thermodynamic models and estimation algorithms as intermediaries between the internal heat exchanger and the control system. These models translate pressure measurements into temperature estimates, enabling indirect temperature control that prevents excessive overheating while preserving the energy efficiency benefits of the internal heat exchanger.
2Measurement precision
If a temperature sensor is installed at the compressor outlet to control discharge temperature, then the temperature control precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent creates a virtual temperature measurement by copying and processing pressure signal data through thermodynamic models. Instead of directly measuring temperature with a sensor, the system calculates equivalent temperature information from pressure measurements, eliminating the need for additional temperature sensors while maintaining control precision.
Solution Approach 2:
The patent replaces the physical temperature sensor (mechanical/thermal measurement device) with a computational model that uses pressure sensors and thermodynamic equations. This substitution eliminates the need for additional temperature sensing hardware while achieving equivalent temperature control functionality through mathematical modeling.
3Ease of operation
If the expansion member opening is adjusted to achieve zero overheating at the evaporator outlet, then the temperature control is simplified, but the reliability decreases due to risky assumptions
Solution Approach 1:
The patent implements a feedback control mechanism that continuously monitors pressure measurements and adjusts the expansion member opening based on estimated temperature conditions. This closed-loop approach replaces risky open-loop assumptions with reliable feedback-based adjustment, ensuring discharge temperature safety while maintaining operational simplicity.
Solution Approach 2:
The patent performs preliminary estimation of temperature conditions using pressure data and thermodynamic models before actual temperature issues occur. By proactively calculating and responding to temperature trends based on pressure measurements, the system prevents unsafe conditions rather than reacting to them, improving reliability while keeping control straightforward.
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 controls compressor discharge temperature independently of temperature sensors, reducing costs and risks while maintaining efficient operation of air conditioning loops with internal heat exchangers, ensuring the refrigerant fluid does not exceed predefined limit temperatures.
Implementation Method 1
an internal heat exchanger for carrying out heat exchanges between the fluid circulating between the condenser and the expansion device and the fluid circulating between the evaporator and the compressor
Implementation Method 2
one condenser
Implementation Method 3
one evaporator
Data Source
Figure 1~4
Figure 2
Figure 3
AI summary
The present invention relates to a method for controlling the outlet temperature (TRCPO) of a compressor (CP) built into the air-conditioning loop of a vehicle in which a subcritical refrigerant flows and including a condenser (CD), an expansion valve (EXV), and an evaporator (EV). The monitoring method comprises the steps of: calculating a limit temperature at the compressor inlet (TRCPI_L); estimating a temperature at the compressor inlet (TRCPI_E); and modifying a control signal of the compressor (PWMcp) or a setpoint value of the evaporation temperature (SP_TEV).