Automotive engine camshaft Valve important parts, camshaft design and processing quality is good or bad, directly affects engine performance. In recent years, because of the need for environmental protection, it is the development of low fuel consumption, low pollution engines. To solve the problem of vehicle exhaust pollution emissions, to achieve high engine speed, high output power, and many multi-valve engine and valve timing, variable valve lift structure, which increases the valve spring load. Meanwhile, in order to reduce fuel consumption and friction loss between the cam and rocker arm roller structure adopted, the cam and the roller contact surface to form a high pressure area, which the camshaft movement smoothness, balancing, wear resistance and torsional strength put forward higher requirements. Further, in order to achieve the car light, low-cost purposes, without affecting the performance requirements of the various parts of the premise, it should be as simple as possible so that parts processing, reduce weight, material use is also more reasonable.

Camshaft configuration

Camshaft and the cylinder head of the body is a cylindrical rod of the same body. The above has several sets of cams, and the other end is connected to the drive wheels.

Side cam was egg-shaped.  Its design goal is to ensure adequate cylinder intake and exhaust, as far as possible in a short time the valve opening and closing operation. Also taking into account the durability of the engine and the smoothness of the operation, the valve opening and closing operation can not be due to the deceleration process produces too much too big impact, otherwise it will cause the valve of serious wear and tear, noise increases, or other serious consequences. Thus, the cam and engine power, torque and smoothness of operation has a very direct relationship.

Generally, inline engine, a cam on the corresponding one of the valve.  V-type engine or a horizontally opposed engine is two valves per share a cam. The rotary engine and gas engine with no valves due to its special structure, does not need cams.

In order to reduce the weight, ease of processing and cost, as well as the engine of high speed, high output power, engine components, especially the camshaft design must be reconsidered, requires its compact, functional and highly concentrated, light weight, can withstand higher The contact pressure. In the current camshaft applications, centralized lubrication system has been head of the hollow camshaft, direct injection will achieve fuel pump on the camshaft drive assembly to achieve the VVT (variable valve timing) in the camshaft tail end use. In gas distribution mechanism, all parts of the camshaft performance requirements are different. For cam and fuel pump drive wheels require abrasion resistance, sticking, resistance to pitting corrosion; journal requirements for good sliding properties; rigidity is required for the shaft, bending, twisting and good performance.

Camshaft species

Most traditional camshaft machining steel manufacturing casting or forging production, the individual is also useful.  Casting camshaft mainly chilled cast iron, hardened cast iron.  To reduce weight, the use of some core cast camshaft, the shaft was hollow shape.  In Japan in chilled cast iron camshaft, mainly in the United States in order to quench the main cast camshaft.  In order to make the engine better performance in recent years has developed a heavy financial chilled cast iron, ductile iron and other forms of camshaft, cost and other reasons but its scope of application is limited to individual areas.

Forged steel camshaft to be mainly hot forging, induction hardened cam part, is mainly used on medium-sized engines.  Because of its better pitting resistance, and the valve tappet combination of more overhead (OHV) mechanism used, are also used in mating with the rocker cam mounted on the diesel engine (OHC) structure.     Because lightweight forged camshaft can not be achieved, the development potential is small.

Casting camshaft production process as Chilled cast iron.  Chilled cast iron products, European countries have already started to develop in the early twentieth century, widely promoted in the late sixties and the seventies, eighties technology is fully mature.  Chilled cast iron products for its low cost, high performance significantly, which is widely used in internal combustion engines.  In other countries, the internal combustion engine industry, 43% - 47% of the gasoline engine, diesel engine camshaft chilled cast iron as a material chilled cast iron camshaft material commonly used as its low-cost, high-performance notable features, has been widely used.

Performance and Application of Chilled Cast Iron Camshaft

Chilled cast iron because of its high hardness carbide structure and has good abrasion resistance and scratch resistance. Chilled cast iron in the white layer is ledeburite, at room temperature.