Air conditioning control
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Solution Overview
Problem
The existing air conditioning systems in vehicles rely on temperature sensors to control the evaporator, but if the sensor fails, it can lead to loss of cabin cooling and air dehumidification, causing issues like windscreen misting.
Innovation Solution
A method for controlling an air conditioning system that calculates a mass flow rate based on blower speed, determines a heating level based on heater parameters, and estimates the evaporator operating temperature using discharge temperatures, heating levels, and mass flow rates, allowing for compressor control and fault detection without relying solely on temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to monitor the evaporator, then the evaporator temperature can be controlled correctly, but the system reliability deteriorates when the sensor fails
Solution Approach 1:
The patent creates a virtual copy of the temperature sensor by calculating an estimated evaporator temperature using discharge temperature sensor readings, heating level, and mass flow rate. This calculated temperature serves as a backup measurement that can replace the physical evaporator temperature sensor when it fails, thereby maintaining system reliability without sacrificing measurement precision.
Solution Approach 2:
The patent introduces an intermediary calculation method that uses the discharge temperature sensor (located downstream) combined with heating level and mass flow rate information to derive the evaporator temperature. This intermediary approach allows indirect measurement of evaporator temperature when direct sensing is unavailable, resolving the contradiction between measurement precision and reliability.
2Reliability
If the evaporator temperature sensor fails, then the compressor may be disabled, but this causes loss of cabin cooling and dehumidification
Solution Approach 1:
The patent creates a virtual temperature sensor that calculates evaporator temperature from discharge temperature, heating level, and mass flow rate. This virtual sensor enables continuous compressor operation and maintains cabin cooling functionality even when the physical evaporator temperature sensor fails, eliminating the need to disable the compressor while preserving fault detection through comparison of measured versus calculated temperatures.
3Reliability
If the evaporator temperature sensor fails, then air dehumidification is lost, but this causes windscreen misting
Solution Approach 1:
The patent implements a virtual evaporator temperature sensor that calculates the evaporator temperature using discharge temperature sensor readings, heating level, and mass flow rate. This calculated temperature enables continuous air dehumidification function even when the physical sensor fails, preventing windscreen misting while maintaining the ability to detect sensor faults through temperature comparison.
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 method enables effective control of the air conditioning system, maintains cabin cooling and dehumidification, and detects potential faults in temperature sensors, thereby preventing issues like windscreen misting.
Implementation Method 1
a blower unit configured to generate an airflow along the duct... from a location in the duct before the evaporator and heater to a location in the duct after the evaporator and heater
Implementation Method 2
The purpose of the evaporator is to condition an airflow moving through the evaporator. The conditioning of the air may involve changing the humidity level of the airflow and/or cooling the airflow.
Implementation Method 3
a first heater... located in the duct... calculating a first heating level of the air conditioning system based on at least one first heater parameter associated with the first heater
Implementation Method 4
A compressor is generally used to drive the evaporator to a selected operating temperature
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Method for controlling an air conditioning system (10) of a vehicle (1), the air conditioning system (10) comprising a blower unit (12), a duct (14), an evaporator (17), a first heater (23) and a first discharge temperature sensor (25), the evaporator (17) and the first heater (23) being located in the duct (14), the blower unit (12) being configured to generate an airflow along the duct (14) and to generate the airflow at a variable blower speed, the first discharge temperature sensor (25) being configured to output a first discharge temperature sensed from the airflow in the duct (14) located after the evaporator (17) and the first heater (23), the method comprising calculating a mass flow rate based on the blower speed of the blower unit (12), calculating a first heating level of the air conditioning system (10) based on at least one first heater parameter associated with the first heater (23), and calculating an estimated evaporator operating temperature of the evaporator (17) based on the first discharge temperature, the first heating level, and the mass flow rate.