How much do you know about the failure mode and transmi […]
How much do you know about the failure mode and transmission mode of the camshaft
Failure forms of camshafts
The camshaft is a device that makes the engine valve open or close at the right time, and is generally used in various piston engines. Because its cross-sectional shape is similar to that of a peach, it is also called a peach-shaped shaft or an eccentric shaft. The structures of the camshafts of various engines are quite different. The main difference lies in the location of the device. The number and shape of the cams are different, especially the location of the device, which is an important indicator to measure the structure and performance of the engine. The following camshaft wholesale, camshaft manufacturers and camshaft brand companies will talk about the failure modes of camshafts.
The contour line of the camshaft directly controls the opening rules and fuel injection rules of the engine valves. Since the valve opening and fuel injection are intermittent, the camshaft surface is subjected to periodic shock loads. The contact surfaces of the camshaft and the push rod roller form a pair of conflict pairs. There is line contact between them, and the surface stress is as high as 3000Mpa to 5000Mpa, and there is a certain relative sliding, so under normal circumstances, it will also wear and fail. The failure mode of the camshaft is mainly wear, abrasion and pitting on the surface of the cam.
What are the main transmission modes of camshafts?
1. Cylindrical gear transmission
For the upper-mounted camshaft and the lower-mounted camshaft, the valve organization is mostly driven by a cylindrical timing gear, and the crankshaft gear meshes with the camshaft gear through the central gear. The timing gears use helical teeth to ensure smooth meshing and reduce noise. Gears are made of steel or cast iron. Advantages: simple structure and process, convenient disassembly and assembly, and reliable process. However, when the upper-mounted camshaft is selected for gear transmission, the number of central gears increases, which increases the complexity and weight.
2. Bevel gear drive
This transmission method is mostly used in the transmission of overhead cams of light-duty high-speed and high-power internal combustion engines. Because the camshaft is far away from the crankshaft, bevel gears and vertical elastic shafts are used for transmission. Its characteristics are: the structure is compact and reliable, but it is very messy and inconvenient to disassemble and assemble.
3. Chain drive
The chain drive is selected for some upper-mounted camshaft valve organizations, which can protect the valve organization from inertial loads. This device requires high quality of the chain, and the chain should have a certain tension during operation to avoid de-chaining. , Therefore, it is equipped with a slack stop sprocket, and the tension of the chain can be changed by adjusting the position of the slack stop sprocket.