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Camshaft Strength And Reliable Support Requirements Are High

Jul 19, 2017

The position of the camshaft position sensor varies depending on the position of the camshaft. When the camshaft is placed in the center of the camshaft, the camshaft position sensor of the electronic control diesel engine is often installed on a high pressure pump (sometimes referred to as a high pressure pump phase sensor) Or a single pump, the camshaft position sensor is located on the cylinder head when the camshaft is placed on the cylinder head.

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.

Camshaft structure

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. Figure 1 shows the camshaft used by the Mitsubishi 4G63 DOHC engine.

The camshaft is erected so that the distance between the camshaft and the valve becomes smaller, so the transmission rocker can be made short and light, and can be used to drive the valve directly without using the rocker arm. In addition, after the intake camshaft and the exhaust camshaft are separated, the degree of freedom of the valve arrangement is increased, and the spark plug can be easily arranged between the two camshafts, which can be arranged at the center of the combustion chamber. Making the double overhead camshaft more suitable for high-speed engines.

The camshaft is located almost at the end of the engine lubrication system, so the lubrication condition is not optimistic. If the oil pump because of the use of time is too long and other reasons there is insufficient fuel supply pressure, or lubricating oil blockage caused by lubricating oil can not reach the camshaft, or bearing cover tightening bolts tightening torque is too large to cause the oil can not enter the camshaft clearance, Resulting in abnormal wear of the camshaft