Automotive Camshaft Higher Requirements For Resisting Wear Resistance And Torsional Strength
Automotive Automotive Camshaft is an important part of automobile engine valve, and the structure design and processing quality of Automotive Camshaft directly affect the performance of engine. In recent years, because of environmental protection needs, is developing low fuel consumption, low pollution of the engine. In order to solve the problem of vehicle exhaust pollution, the engine's high speed, high output power, many engines with multiple valves and gas phase, valve lift variable structure, which increases the load of the valve spring. At the same time, in order to reduce the fuel consumption and friction loss, the roller structure between cam and rocker arm, the contact surface of cam and roller form a high pressure zone, which puts forward higher requirements for the smoothness, dynamic balance, wear resistance and torsional strength of Automotive Camshaft movement. In addition, in order to achieve the purpose of automotive light, low-cost, without affecting the performance requirements of each part of the premise, should make the parts as simple as possible, reduce the weight, the use of materials also more reasonable.
The main body of the Automotive Camshaft is a cylindrical bar with the same length as the cylinder group. The upper cover has several cams and the other end is connected with the driving wheel.
The side of the cam is egg-shaped. The aim of the design is to ensure full air intake and exhaust of the cylinder, and to complete the opening and closing action of the valve in a short time as far as possible. In addition, considering the durability of the engine and the smoothness of the operation, the valve can not be caused by the deceleration process in the opening and closing actions too much impact, otherwise it will cause serious valve wear, noise increase or other serious consequences. Therefore, the cam and engine power, torque output and the smoothness of the operation has a very direct relationship.
In general, in a straight-line engine, a cam corresponds to a valve. A V-type engine or a horizontal alignment engine is a cam that is shared by each of the two valves. The rotor engine and the valveless valve engine have no need of Cam because of their special structure.
In order to achieve lightweight, easy to process and low-cost, and the engine's high speed, high output power, engine parts, especially the design of the Automotive Camshaft must be reconsidered, requiring its compact structure, high concentration of functions, light weight, can withstand higher contact pressure. In the current Automotive Camshaft application, the cylinder head lubrication system has been concentrated in the hollow-type Automotive Camshaft, the fuel pump driver component in the cylinder is realized on the Automotive Camshaft, and the VVT (variable timing valve) is used at the end of the Automotive Camshaft. In the gas distribution mechanism, the performance requirements of the Automotive Camshaft are different. For the cam and fuel pump driving wheel, it is required to wear resistance, resistance, pitting corrosion, for the requirements of the axle-neck sliding performance is good, for the shaft requires rigidity, bending, torsional performance.
The traditional Automotive Camshaft is mostly made by casting or forging, and individual is also useful for cutting and manufacturing of carbon steel. Casting Automotive Camshaft mainly has chilled cast iron, quenching cast iron and so on. In order to reduce the weight, some of the Automotive Camshaft using core casting, so that the shaft is hollow-shaped. In Japan, chilled cast iron Automotive Camshaft is the main, in the United States with quenched cast iron Automotive Camshaft. In order to make the engine performance better, in recent years has developed a heavy melting chilled iron, quenching ductile iron and other forms of Automotive Camshaft, but because of cost and other reasons, the scope of application is limited to individual areas.
The forging type Automotive Camshaft is mainly used for hot forging of carbon steel, and the cam part adopts high-frequency quenching treatment, which is applied to medium and large engine. Because of its good pitting resistance, it is used in combination with the tappet of Valve top (OHV) mechanism, and with the rocker arm applied to the diesel engine cam top-mounted (OHC) structure. Because the forging Automotive Camshaft cannot realize lightweight, the development potential is small.
Casting Automotive Camshaft production process for cold shock cast iron. Cold-shock cast iron products, Europe and the United States early in the early 20 has begun to develop, widely spread in the last century $date, 80 's technology fully mature. Cold-shock cast iron products are widely used in internal combustion engines because of their notable characteristics of low cost and high performance. In foreign countries, 43%~47% gasoline engine and diesel engine are used as Automotive Camshaft materials in the internal combustion engine industry, and cold cast iron is widely used as Automotive Camshaft material for its low cost and high performance.