Vehicle Heat Pump Control for Sensorless Outside Air Estimation
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Solution Overview
Problem
Conventional vehicle air conditioning devices face challenges in accurately estimating outside air temperature without using an outside air temperature sensor, leading to reduced user comfort and fuel efficiency due to inaccurate detection, especially when the sensor is influenced by hot air from the engine and motor components.
Innovation Solution
A vehicle air conditioning device that estimates outside air temperature using a combination of high pressure side pressure detected by a high pressure side pressure sensor, heater core inlet refrigerant temperature from a heater core inlet refrigerant temperature sensor, and solar radiation, with correction maps to improve estimation accuracy, allowing for accurate air conditioning control even when the outside air temperature sensor is inaccurate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an outside air temperature sensor is installed in the front compartment near the powertrain, then the sensor can detect outside air temperature, but the detection accuracy deteriorates due to hot air influence from the engine and motor components
Solution Approach 1:
The patent extracts the temperature sensing function from the physical outside air temperature sensor and relocates it to the refrigerant cycle system. By measuring the temperature of the refrigerant (which is thermally coupled to the outside air through the condenser) and correcting it based on powertrain heat influence, the system obtains accurate outside air temperature without placing a sensor in the hot air zone near the powertrain.
Solution Approach 2:
The patent introduces the refrigerant as an intermediary medium between the outside air and the temperature measurement system. The refrigerant absorbs heat from the outside air through the condenser, and its temperature serves as a proxy for outside air temperature. Correction values are then applied to account for powertrain heat influence, yielding accurate outside air temperature readings without direct sensor exposure to hot air.
2Device complexity
If refrigerant pressure is used to estimate outside air temperature, then the cost of the air conditioning device is reduced by eliminating the outside air temperature sensor, but the temperature estimation accuracy deteriorates
Solution Approach 1:
The patent changes the measurement parameter from refrigerant pressure alone to a combination of refrigerant temperature and correction values. By measuring refrigerant temperature (which has a stronger correlation with outside air temperature than pressure) and applying correction factors based on powertrain operating conditions, the system achieves accurate outside air temperature estimation without requiring an expensive outside air temperature sensor.
Solution Approach 2:
The patent replaces the mechanical/outside air temperature sensor system with a thermal measurement system based on refrigerant temperature. This substitution uses the existing refrigerant cycle components as the measurement basis, eliminating the need for separate outside air temperature sensing hardware while improving accuracy through proper temperature measurement and correction.
3Device complexity
If the outside air temperature sensor is removed to reduce costs, then the device complexity is reduced, but the air conditioning control accuracy deteriorates
Solution Approach 1:
The patent makes the refrigerant cycle system multi-functional by having it serve both its primary cooling/heating function and the secondary function of outside air temperature measurement. The refrigerant temperature measurement, which is already part of the air conditioning control system, is utilized dual-purpose to determine outside air temperature, eliminating the need for a separate sensor while maintaining control accuracy.
Solution Approach 2:
The air conditioning system serves itself by using its own refrigerant temperature measurements to determine outside air temperature. The system's existing thermal measurements and control data are repurposed to provide accurate outside air temperature information, making the system self-sufficient and eliminating the need for additional external sensors.
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
The solution enables precise estimation and control of outside air temperature, enhancing user comfort and maintaining fuel efficiency by adjusting cabin temperature and airflow based on calculated estimates rather than sensor readings, especially during vehicle stoppages or low speeds.
Implementation Method 1
a high pressure side pressure sensor configured to detect a pressure on the high pressure side of the air conditioning cycle
Implementation Method 2
a heater core inlet refrigerant temperature sensor configured to detect a temperature of the second refrigerant at an inlet of the heater core
Implementation Method 3
a heater core through which a second refrigerant circulates, the heater core being configured to heat air that is to be supplied to a vehicle cabin
Implementation Method 4
a compressor configured to compress the refrigerant
Implementation Method 5
an expansion valve configured to expand the compressed refrigerant
Data Source
AI summary
Disclosed is a vehicle air conditioning device including a heat pump cycle configured to compress and expand a refrigerant; a heater core; a high pressure side pressure sensor configured to detect a pressure on the high pressure side of the heat pump cycle; and a heater core inlet water temperature sensor configured to detect a temperature of cooling water at an inlet of the heater core as a heater core inlet water temperature. The heat pump cycle includes a compressor; a condenser; a water refrigerant heat exchanger and an evaporator; and a heating expansion valve and a cooling expansion valve. An estimated outside air temperature is calculated based on the high pressure side pressure detected by the high pressure side pressure sensor and the heater core inlet water temperature detected by the heater core inlet water temperature sensor.