The cylinder head is the upper part of an internal combustion engine that allows the combustion chambers to close. It constitutes the upper closure of the motor block and in motors the valves are seated on it, having holes for this purpose.
The cylinder head has a double wall to allow the circulation of the coolant. If the internal combustion engine is an ignition ignition (Otto engine), it has threaded holes where the spark plugs are located. In case of compression ignition (diesel engine) instead it has the holes for the injectors.
The cylinder head is fixed by screws or studs on the upper plane of the block and serves as a watertight cover for the cylinders, since it houses all or part of the combustion chamber, except in the case that it is formed in the piston head.
Many elements are installed in the cylinder head. These include: in the case of 4-stroke engines, valves and mechanisms to drive them; ignition and injection elements, intake and exhaust manifolds, etc. In the cylinder head, the coolant chambers are also machined.
What is the cylinder head gasket?
The cylinder head is made of cast iron or light alloy and is attached to the cylinder block by means of screws and a gasket: the cylinder head gasket.
The cylinder head gasket serves to ensure a perfect seal between the cylinder head and the cylinder block and taking into account that it has to withstand high pressures and temperatures. The cylinder head gasket is manufactured manufactures with synthetic fibers to replace asbestos, so negative for health.
What material is the cylinder head of an engine made of?
Cylinder heads are generally made of aluminum alloy, a material with a low specific weight and good thermal conductivity, which allows heat to be quickly evacuated. Cylinder heads for 2-stroke engines (small cylinder motorcycles) are simpler, since they do not have a distribution, and they are air-cooled.
The engine cylinder head is the nomenclature used to refer to part of a mechanism. In a cylinder head internal combustion engine cylinder head and top cover and cylinder block consists of a cutter they fit the metal block platform so perfectly to provide explosion resistance.
Currently the cylinder head of the engine is the upper part of the combustion chamber and where the candles and the intake valves and the exhaust head are located. Between and the block is the cylinder head gasket in addition to facilitating engine maintenance, the cylinder head is the key to proper operation, to determine the shape of the combustion chamber, the intake and exhaust passage, the valve operation and command. You can develop totally different engine performance just by changing the head.
It is usually made from the same rest of the block material, cast iron, or high-performance motors, aluminum alloys. Like the rest of the apple it contains pass separate pipes for lubricant and cooling water.
How is the design of the cylinder head of an engine?
Cylinder head design must take several factors into account. These factors include:
- The determination of the thermal field to which a multi-cylinder engine cylinder head is subjected.
- The contributions of the board
- Valve seats
- Valve guides
- Bolts and clamping nuts
- Engine type service period
- On and off transients
- The full minimum load conditions typical of bench life tests.
Stress analysis follows several steps:
- simulating the exhaust gas flow to obtain the heat exchange coefficients and the heat fluxes on the part surfaces;
- the calculation of the thermal transient simulating the heating and cooling of the piece;
- Mechanical calculation with the temperature range as a voltage parameter to which most mechanical loads are superimposed.
- The thermal field of the cylinder head, especially in the area close to the plane of the flame. Despite having areas with temperatures of 140 ° C and an average temperature of around 180 ° C, other parts can reach particularly high temperatures. High temperatures have to be taken into account especially for cylinder heads equipped with two paired exhaust pipes, where the cross bar that separates them can reach 250 ° C. These areas are critical since they generate hot spots and are subject to many stresses, which can lead to the creation of many cracks at these points.