Long gone are the days when the ambient temperature was measured only alcohol or mercury thermometer. Today there is a wide variety of temperature sensors. With their help, measured the air temperature in the premises and on the street. Such sensors are included in the electronic control circuit climate systems and engine management systems of cars.
The air temperature sensor: description
The principle of operation of the temperature sensor lies in the physical effect of changing electrical parameters under the influence of temperature. Often the thermocouple sensor when the temperature changes the electrical resistance. And this parameter is easy to fix and use in any circuit like a simple fixing of the result, and for subsequent management.
For fixing high temperatures more suitable sensors for thermocouple, but they are less accurate. Then as the air temperature sensor with RTD is accurate to 1 degree Celsius. The use of such models can be detected everywhere. The most widespread find in the climate control of the premises and the automotive industry.
The easiest air heater already has a built-in thermocouple. It allows him to disconnect upon reaching a predetermined temperature. It is also convenient to put the program automatic switch-on when cold. The sensors have successfully integrated into Underfloor heating systems. In principle, any heating system is composed of at least one air temperature sensor.
Automotive temperature sensors
Every car owner knows how difficult it is sometimes an electric component of his car. Each element of such a system is an important link and its failure can bring different amounts of trouble. Where is the air temperature sensor in car and what does it do?
Since the air is no longer exposed to the fuel mixture in the common duct, and was properly calculated without human intervention, the temperature sensors are firmly settled in the car. There are two main areas where it is present the thermostat with air temperature sensor.
1. System for creating air-fuel mixture for the engine. As the sensor used here is a simple thermistor. When the temperature is fixed changes in electrical resistance. This is necessary in order to determine whether the amount of fuel feeding with the intake air. Cooler air has a higher density and requires a greater amount of gasoline or diesel fuel to the same volume of the mixture.
2. The air conditioning system of the vehicle. For full operation of the system requires the presence of several detectors. But to estimate the surface temperature of the street you can do one.
Location of thermal sensors
Temperature sensor intake air of the engine is most often installed in the center of the front bumper. Because in that location car for the first time meets the incoming air, and is heated from the engine. Anywhere under the hood there will be distortion.
In cars where a mass air flow sensor is installed, there may not be a separate inlet temperature sensor. It is part of DFID. For climate control systems, the sensor can be placed at the bottom of the windshield.
This files most often out of order, temperature sensors, standing in the engine compartment, or worse, in the intake manifold. In the event of excessive heating, in the best case, temperature sensor intake air just starts to “lie”. And sometimes just collapses. It is important that the debris item has not got to the engine.
In some cases, the temperature sensor may simply be covered with a thick layer of dirt. It will be enough to clear the element to return it to work.
Replace the faulty sensor should be on the same or similar properties. Incorrect replacement in the best case it will give error. For example, there are known cases of replacement temperature sensor air temperature sensor fluid. The air temperature was also measured, but with a very high inertia.
Diagnosis and consequences
It would seem that it can be difficult to fault detection of temperature sensor. In practice, to see the discrepancy in measured temperature are real, only in the case of a large difference. As for the faulty engine temperature sensor intake air – or fuel consumption or hard starting in the cold season.
The most reliable diagnosis is made using a multimeter. First removed the sensor and measured the resistance without stress, and then the element is heated. If the resistance is changed at specified intervals, all is well. If the changes are not committed – it is an obvious fault.