Views: 89 Author: Site Editor Publish Time: 2020-03-25 Origin: Site
Last time, we introduced air flow sensors, intake pressure sensors, throttle position sensors, and water temperature sensors. Today we introduce the remaining four automotive sensors. They are camshaft position sensor, crankshaft position sensor, knock sensor, oxygen sensor.
Camshaft position sensor, also known as cylinder identification sensor, is usually installed in the distributor. It is mainly used to detect the angular position of the camshaft. The ECU determines the top dead center position of a cylinder through this signal and the crankshaft position sensor to determine the ignition timing and sequential injection of the engine.
If the camshaft position sensor fails, the car will have the following symptoms:
(1) The car has a high-pressure fire, but it is difficult to start.
(2) At the same time, the crankshaft reverses during the starting process.
(3) Tempering may occur in the intake manifold.
(4) Car idling is unstable. The car has a severe jitter phenomenon, similar to a car lacking a cylinder failure.
(5) The car is unable to accelerate.
(6) The fuel consumption of automobiles becomes large. Exhaust emissions exceed standards and the exhaust pipe emits unpleasant black smoke.
Crankshaft position sensors are generally divided into three types: electromagnetic crankshaft position sensors, Hall-type crankshaft position sensors, and photoelectric crankshaft position sensors. It is generally installed in the vehicle's distributor, the side of the crankshaft pulley and the front of the camshaft. The crankshaft position sensor is a very important sensor in a vehicle-controlled ignition system. Its role is to detect the top dead center signal, crankshaft rotation signal and engine speed signal, and feed these signals back to the computer, so that the computer can control the fuel injection amount, injection timing and optimal ignition timing.
If the crankshaft position sensor fails, the ECU cannot receive the signal from the crankshaft position sensor. In order to protect the engine, the car will have no high-voltage electricity, no fuel injection and no ignition.
The knock sensor is an important sensing element for adjusting the ignition timing. There are two types of knock sensors: piezoelectric and porcelain telescopic. The knock sensor is generally installed on the upper part of the engine block. Taking a four-cylinder machine as an example, the knock sensor is installed between the 2 and 3 cylinders, or the middle of the 1 and 2 cylinders and the middle of the 3 and 4 cylinders. Its role is to measure the engine vibration and use the piezoelectric effect to convert the mechanical vibration generated during knocking into a signal voltage. If the knock sensor is damaged, the ECU cannot monitor the extent of the knock, so it will incorrectly determine that no knock has occurred. In this case, the engine control unit will increase the ignition advance angle, causing the engine to shake rudely due to knocking.
Cars exhibit the following symptoms:
(1) The engine shakes slightly.
(2) The power of the engine is insufficient.
(3) Fuel consumption of automobiles has increased.
(4) The power of the engine will decrease.
The oxygen sensor is mounted on the exhaust pipe. It is used to detect the concentration of oxygen in the exhaust gas to determine the richness and leanness of the mixture, and then correct the air-fuel ratio to determine the combustion status of the engine (front oxygen) or the operating efficiency of the catalyst (rear oxygen), and control the fuel injection amount .
If the oxygen sensor fails, the ECU cannot tell whether the amount of gasoline injected is correct. The result of this is that the concentration of the mixer is too thick or too thin. Insufficient combustion reduces engine power and increases emissions and pollution.
If there is a problem with the oxygen sensor, the car will have the following symptoms:
(1) Fuel consumption of automobiles has increased.
(2) Increased emissions of pollutants. Exhaust pipe emits black smoke.
(3) The engine speed is unstable and trembling.
With more and more automotive electronics, more and more sensors are installed in cars. In addition to these eight sensors, we also need to install tire pressure monitoring systems. As an important part of a car, the main consideration for tire performance is the tire pressure. Too low or too high air pressure of the tire will affect the performance of the tire and reduce its service life, and ultimately affect driving safety.
