Vehicle Ambient Air Temperature Sensor with Active Compressor Control
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Solution Overview
Problem
Conventional temperature measurement sensors in vehicles suffer from inaccuracies, especially at low speeds, due to proximity to heat sources and environmental heating effects, leading to incorrect air temperature determination, which affects ultrasound-based distance measurements in parking assistance systems.
Innovation Solution
A temperature measuring device integrated into the airflow path of a vehicle, utilizing a compressor unit to generate and control airflow for precise temperature measurement, coupled with a control unit to adjust compressor output based on airflow rate and speed, ensuring accurate external air temperature determination even at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is installed near heat sources (engine, exhaust gas system, brake) in the vehicle, then the sensor is protected from environmental exposure, but the measured temperature deviates significantly from the actual ambient air temperature
Solution Approach 1:
The temperature measurement function is extracted from the vehicle interior environment and placed in the exterior airflow path. The sensor is taken out from the protected but thermally contaminated interior location and positioned where it directly experiences ambient air flow, eliminating the thermal interference from engine and exhaust systems.
Solution Approach 2:
A compressor unit is introduced as an intermediary device to actively transport ambient air from the exterior environment to the temperature sensor. This mediator overcomes the low airflow condition at low vehicle speeds by mechanically forcing air flow through the sensor, ensuring accurate temperature measurement without direct exposure to interior heat sources.
2Measurement precision
If the vehicle travels at high speed (above 80 km/h), then wind resistance provides sufficient airflow for accurate temperature measurement, but at low speeds these heating effects occur and correct temperature determination becomes impossible
Solution Approach 1:
The air supply system transitions from a passive, speed-dependent airflow (natural convection at high speeds) to an active, controllable airflow system using the compressor unit. The compressor dynamically adjusts its operation based on vehicle speed, providing sufficient airflow at low speeds while avoiding unnecessary operation at high speeds when natural convection is adequate.
Solution Approach 2:
The system changes the airflow parameter from naturally varying with vehicle speed to actively controlled. The compressor unit modifies the airflow rate parameter to maintain consistent temperature measurement conditions across different vehicle speeds, particularly ensuring adequate airflow at low speeds where natural convection is insufficient.
3Measurement precision
If the compressor unit operates continuously to ensure sufficient airflow for temperature measurement, then accurate temperature data is available at all speeds, but energy consumption increases
Solution Approach 1:
The compressor unit operates periodically rather than continuously, activating only when vehicle speed falls below a predetermined threshold where natural convection is insufficient. This periodic operation maintains measurement precision during critical low-speed conditions while minimizing energy consumption during high-speed operation when ambient airflow is adequate.
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 solution enables precise and reliable external temperature measurement, improving the accuracy of ultrasound-based distance calculations and providing timely temperature information to drivers across all speed ranges.
Implementation Method 1
a compressor unit (18) disposed in the flow path (14)
Implementation Method 2
thermal convection from the ground surface
Implementation Method 3
the propagation time between transmission and reception and also on the basis of the propagation speed of sound in the propagation medium
Implementation Method 4
a piezoceramic oscillator in the form of a thin disc for transmission and reception of ultrasonic signals
Data Source
AI summary
The invention relates to a temperature measuring device for measurement of the external temperature of the ambient air in a vehicle, wherein the temperature measuring device is disposed in a flow path of an air flow and the air flow can be generated from ambient air of the vehicle both through speed-dependent wind resistance of the vehicle and/or wind and also through a compressor unit disposed in the flow path.