Although the speed of the camshaft is half the speed of the crankshaft in a four-stroke engine, its speed is still high and requires a lot of torque, so the requirements for the strength and reliability of the camshaft are high. The main body of the camshaft is a cylinder with the same length as the cylinder block. There are a number of cams. The material of the camshaft is usually special cast iron, sometimes made of forged and alloy. Most of the interior of the camshaft is made into a hollow structure, which not only reduces the quality of the camshaft, but also improves the ability of the cam bearing to be loaded. The camshaft is also machined with a lubricating oil passage, which is lubricated by the camshaft, rocker shaft, and rocker arm.
Camshaft position sensor is also called synchronous signal sensor, it is a cylinder identification positioning device, input to the ECU camshaft position signal, is the ignition control of the master signal.
The camshaft position sensor acquires the position signal of the camshaft camshaft and inputs the ECU so that the ECU recognizes the cylinder 1 to compress the top dead center so as to perform sequential injection control, ignition timing control and deflagration control. In addition, the camshaft position signal is also used to identify the first ignition timing when the engine is started. Because the camshaft position sensor can identify which cylinder piston is about to reach the top dead center, it is also known as the cylinder identification sensor.
The engine computer controls the four cylinders according to the camshaft position signal and the crankshaft position signal in the order of 1-3-4-2.
When the engine computer can not receive the camshaft position signal, according to the 1,4 cylinder at the same time injection, 2,3 cylinder jet injection control the way. Because the ignition coil to produce double spark, so the engine can still start and run, then deflagration control off, ignition advance angle delayed, the output power down.
Is a part of the piston engine. Its role is to control the valve opening and closing action. Although the speed of the camshaft in the four-stroke engine is half the crankshaft (the camshaft has the same speed as the crankshaft in the two-stroke engine), it is usually very high in speed and requires a lot of torque, Camshaft in the strength and support requirements are high, the material is generally special cast iron, and occasionally with forgings. As the valve movement law relates to the power and operation characteristics of an engine, so the camshaft design in the engine design process occupies a very important position.
1). The dimensional accuracy of the bearing journal and the coaxiality between the bearing journals
2). Keyway size and position accuracy
3) The verticality of the thrust surface relative to the support journal line
4). The dimensional accuracy of the cam base circle and the coaxiality with respect to the bearing journal axis
5). Cam position accuracy
6). Cam shape accuracy (curve lift) and so on