The principle of the car sensor
The car sensor is the input device of the car computer system. It converts various operating conditions information of the car during operation, such as vehicle speed, temperature of various media, engine operating conditions, etc., into electrical signals to the computer, so that the engine is at its best. Working status. There are many sensors for vehicles. When judging the failure of the sensor, it should not only consider the sensor itself, but also consider the entire circuit of the failure. Therefore, when searching for faults, in addition to checking the sensor, also check the wiring harness, connectors, and related circuits between the sensor and the electronic control unit. Let's take a look at the main sensors in the car.
Air flow sensor
The air flow sensor converts the sucked air into a TES electrical signal and sends it to the electronic control unit (ECU) as one of the basic signals to determine the fuel injection. According to different measuring principles, it can be divided into rotary vane air flow sensor (Toyota PREVIA station wagon), Karman vortex air flow sensor (Toyota Lexus LS400 sedan), hot wire type air flow sensor (for Maxima)
VG30E engine and Volvo B230F engine installed in domestic Tianjin Sanfeng Bus TJ6481AQ4) and four types of hot film air flow sensor. The first two are volume flow type, the latter two are mass flow type. At present, two main types of hot-wire air flow sensors and hot-film air flow sensors are used.
Intake pressure sensor
The intake pressure sensor can measure the absolute pressure in the intake manifold according to the load state of the engine, and convert it into an electrical signal and a speed signal to be sent to the computer together as a basis for determining the basic fuel injection amount of the injector. This pressure sensor is used in domestic Audi 100 cars (V6 engine), Santana 2000 cars, Beijing Cherokee (SEO25L engine), Toyota Crown 3.0 cars, etc. At present, the semiconductor varistor type intake pressure sensor is widely used.
Throttle position sensor
The throttle position sensor is installed on the throttle to detect the opening of the throttle. It links with the throttle through the lever mechanism, and then reflects the different working conditions of the engine. This sensor can input the electronic control unit (ECU) after detecting the different working conditions of the engine, so as to control different injection quantities. It has three types: switch contact throttle position sensor (VPS Santana 2000 car and Tianjin Sanfeng passenger car), linear variable resistance throttle position sensor (Beijing Cherokee), integrated throttle position sensor (domestic Audi 100 type) V6 engine).
Crankshaft position sensor
Also known as crank angle sensor, it is the most important sensor in the computer-controlled ignition system. Its function is to detect the top dead center signal, crank angle signal and engine speed signal, and enter it into the computer, so that the computer can follow the cylinder ignition sequence Issue the best ignition timing command. There are three types of crankshaft position sensors: electromagnetic pulse crankshaft position sensor, Hall effect crankshaft position sensor (Santana 2000 car and Beijing Cherokee), photoelectric effect crankshaft position sensor. Different types of crankshaft position sensors have different control methods and control accuracy. The crankshaft position sensor is generally installed on the side of the crankshaft pulley or sprocket, and some are installed at the front end of the camshaft, and some are installed at the distributor (Santana 2000 car).
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