What are the specific parts of a car's head?

Since engines work on similar principles, the basic structure is much the same. Gasoline engines are usually composed of two major institutions and five systems, and diesel engines are usually composed of two major institutions and four systems (no ignition system).　Engine assembly Crank connecting rod mechanism - to realize the core of thermal energy conversion, but also the engine assembly basis.　Gas distribution mechanism - to ensure that the cylinder gas exchange at the right time.　Fuel system - control the amount of fuel put into the cylinder per cycle to regulate the output power and speed of the engine. Automobile engine cooling system - to control the normal operating temperature of the engine.　Lubrication system - to reduce friction and prolong the service life of the engine.　Ignition system - the timely provision of electric spark to the gasoline engine (diesel engine without ignition system) Starting system - so that the crankshaft rotation to complete the engine starting process. Crank connecting rod mechanism Crank two-rod mechanism in the work stroke, the fuel combustion after the gas pressure, through the piston, connecting rod into the crankshaft rotating torque; and then, the use of the inertia of the flywheel to complete the intake, compression, exhaust 3 auxiliary stroke. Crank connecting rod mechanism cylinder crankcase group, piston connecting rod group and crankshaft flywheel group of three parts.　First, the cylinder block crankcase group 1, the cylinder block and crankcase cylinder block and crankcase are usually cast into one, collectively referred to as the cylinder block, which is the engine shell and assembly basis, generally made of high-quality alloy cast iron or aluminum alloy, and its structural form of inline, V-type, opposed to the type of three kinds. Inline six-cylinder engine cylinder block. The engine is an inline six-cylinder water-cooled gasoline engine. The cylindrical space inside the cylinder is called the cylinder, and the cylinder surface is called the cylinder wall. Cylinder is the place of gas exchange, combustion, but also the piston movement track. In order to ensure the sealing of the piston and cylinder and reduce wear, the cylinder wall should have a higher machining accuracy and lower surface roughness. In order to make the cylinder in the work of the heat to be emitted, in the cylinder block, cylinder liner body between the system can accommodate the coolant of the sandwich cavity, called water jacket.　In the lower part of the cylinder block there are 7 main bearing seats for mounting the crankshaft flywheel set. The side of the cylinder block is equipped with a tappet chamber for mounting the valve transmission components. The upper plane of the cylinder block is fitted with the cylinder head, the lower plane is fitted with the oil pan, and the front face is fitted with the timing gear cover, all of which are gasketed and bolted tightly for sealing. The rear face of the cylinder block is fitted with a flywheel housing.　In order to enhance the wear resistance of the cylinder block to extend the service life of the cylinder block, most of the cylinder liner inlaid in the cylinder body. Cylinder liner is divided into dry and wet show two kinds. Dry cylinder liner is not in contact with the coolant, in order to prevent the cylinder liner downward fluttering, can be in the upper (lower) stop limit. Wet cylinder liner outer surface in direct contact with the coolant, in order to prevent leakage of coolant, the cylinder liner is equipped with 1 to 3 rubber seals at the lower stop.　2, oil pan The role of the oil pan is to store lubricating oil, so commonly known as the oil pan. It is generally made of thin-walled steel stamping, the internal oil stabilizer baffle to prevent excessive agitation of the lubricating oil, the bottom of the oil drain plug in order to replace the lubricating oil.　3, cylinder head The main role of the cylinder head is to close the upper part of the cylinder, and with the top of the piston combustion chamber. On the cylinder head, there are combustion chamber, water jacket, spark plug holes (diesel engines have injector mounting holes), intake and exhaust tracts, valve seat, valve guide holes, etc. The upper part is equipped with rocker arm shaft assembly, and the bottom is equipped with oil drain plug for oil replacement. The upper part is equipped with a rocker arm shaft assembly, closed with a cylinder head cover, and a sealing point gasket is installed between the combined surfaces. Gasoline engine cylinder head is generally integral, but there are exceptions, such as EQ6100-1 engine is two cylinder heads. Cylinder diameter diesel engine with a cylinder cover or two cylinders a cover, up to three cylinders a cover to prevent deformation of the cylinder head.　4, cylinder cushion Cylinder cushion commonly known as cylinder bed, installed between the cylinder head and cylinder block, its role is to seal the cylinder block and cylinder head combined plane to prevent air leakage, coolant leakage and oil leakage. Cylinder cushion is made of asbestos sheet material, some asbestos sheets are made of copper or iron skin on both sides of the bread, and some are made of latex asbestos sheets with steel sheets on both sides of the center for good adaptability. Combustion chamber hole using double-layer or single-layer metal cladding to prevent the combustion gases wash out the asbestos layer. Gas distribution mechanism The role of the gas distribution mechanism is based on the engine's working order and the requirements of the cylinder cycle, open and close the intake and exhaust valves in time, so that the combustible mixture (gasoline engine) or fresh air (diesel engine) into the cylinder, and exhaust gas into the atmosphere.　First, the type and working principle of four-stroke engine widely used valve cam type gas distribution mechanism, which consists of valve group and valve transmission group composed of two parts. According to the different transmission methods, can be divided into timing gear transmission and chain transmission type two; according to the position of the camshaft, can be divided into different lower, can be divided into the lower camshaft type, the middle camshaft type and the upper camshaft type. Lower camshaft type gas distribution mechanism, its working process is: when the engine is working, the crankshaft drives the camshaft to rotate through a pair of meshing timing gears, and when the cam cam tip rises to the highest position, the valve opening is maximum. When the cam's cam tip moves downward, due to the elasticity of the valve spring, the valve and its transmission parts return to their original position, closing the airway. Compared with the lower camshaft-type air distribution mechanism, the center and upper camshaft-type air distribution mechanisms are mostly timing chain or timing belt drives because of the larger distance between the crankshaft and the camshaft. The center camshaft type omits push rods; the top camshaft type omits tappets and push rods. Main parts 1. Valve group The valve group generally consists of valves, valve seats, valve guides, valve seals, valve springs and valve locking plates.　(1) Valve Valves are divided into intake and exhaust valves, which are used to close the intake and exhaust tracts respectively. Valve by the head and rod components, the head made of conical, with the valve seat taper with. Head cone angle, generally 45 °. The same engine intake valve head diameter is larger than the exhaust valve head diameter, in order to improve the engine's filling capacity. Valve rod section is cylindrical, with the valve guide bore with the end of the rod made of ring groove, used to install the valve spring seat locking plate. (2) Valve Seat The valve seat is used to ensure the sealing of the valve and to transfer the heat from the valve head to the cylinder head. Valve seats are generally made of a special alloy in the form of a ring and are tightly set on the cylinder head.　(3) Valve guides Valve guides are used to guide the valves in a reciprocating linear motion and to ensure that the valves and valve seats close in the correct position. In order to prevent the lubricating oil on the cylinder head from entering the combustion chamber through the gap between the valve and the valve guide, the valve guide is equipped with a valve oil seal at the upper end.　(4) Valve spring The valve spring is a cylindrical coil spring which enables the valve to be closed quickly and causes the valve head and valve seat to press against each other to ensure sealing.　2. Valve Transmission Group The function of the valve transmission group is to open and close the valves at the right time in accordance with the working sequence of the engine and to ensure that the valves are sufficiently open.　(1) Camshaft The camshaft is used to control the opening and closing of the valves and to drive the gasoline pump, oil pump, distributor and other parts. The camshaft is equipped with intake cams, exhaust cams, journals, gears to drive the oil pump and distributor, and eccentric wheels to drive the rocker arms of the gasoline pump, etc. The intake and exhaust cams are important parts of the camshaft, and their arrangement on the camshaft is determined by the arrangement of the intake and exhaust tracts.　(2) timing gears and timing chain or timing pulley crankshaft and camshaft transmission is usually completed by timing gears, timing chain or timing drive belt, such as CA6102, BJ492Q engine for timing gear transmission; Beijing Cherokee automobile engine for timing chain transmission; Shanghai Santana automobile engine for timing belt transmission. Four-stroke engine crankshaft rotation for two weeks, the camshaft should be rotated should be a week, so that the intake and exhaust valves are open and closed once, and the valve opening and closing time must be compatible with the needs of the cylinder work cycle. Therefore, whether it is a gear drive or chain drive, must be assembled in accordance with the provisions of the mark, the mark is generally the pit of the wheel tooth parts.　(3) Valve Tappet The function of the tappet is to transmit the thrust of the cam to the pushrod or valve. The type of tappet is bacterial type, cylinder non-hydraulic, cylinder hydraulic type, etc., cylinder hydraulic type, etc., cylinder hydraulic type tappet no valve lash, can reduce the engine noise, but the precision requirements are strict, the cost is high, and more used in the premium car engine.　(4) valve push rod Its role is to tappet thrust to the rocker arm, drive the valve open. The upper and lower ends of the push rod are heat-treated and polished to improve abrasion resistance; there are two types of solid and hollow rods.　(5) Rocker arm and rocker arm shaft assembly Its role is to change the direction of thrust of the push rod (lower camshaft type), tappet (center camshaft type) or cam (upper camshaft type), so that the valves open. Rocker arm shaft assembly is fixed in the upper part of the cylinder head, mainly by the rocker arm, rocker arm automobile engine shaft support, etc., the rocker arm is made of two arms of unequal length, so that the tappet, push rod to a smaller lift can be obtained with a larger valve opening. The long arm end of the rocker arm corresponds to the valve stem, and the short arm end is equipped with an adjusting screw and nut, used to adjust the valve foot clearance. Rocker arm shaft is a hollow shaft, and rocker arm shaft support, rocker arm has through the lubricating oil channel to lubricate the friction surface of the gas distribution mechanism. Fuel supply system I. Role of the gasoline engine fuel system is based on the needs of the engine in different working conditions, the pure air and gasoline formulated into the appropriate proportion of combustible mixture, sent to each cylinder for combustion after the exhaust gas produced into the atmosphere.　Second, the category and performance comparison of gasoline engine fuel system, according to the formation of combustible mixture of different ways, can be divided into carburetor fuel system and gasoline injection fuel system. Both types of fuel systems are used in automobiles, and the gasoline injection fuel system has been popularized more quickly in automobiles. The carburetor type fuel system was once widely used in automobiles. This structure of gasoline engine fuel system has the characteristics of reliable work, simple enough, easy to use and low cost. However, the carburetor can not meet the urgent requirements of modern automobiles to further reduce emissions and improve the power and economy, and gradually lose the former mainstream status. In order to overcome the above shortcomings of the carburetor type fuel system, people have been seeking other better mixture formation methods while developing the carburetor type fuel system. In the 1950s, research on gasoline injection technology was just a prelude. At that time, the focus of research was on how to improve engine output and instantaneous response performance, while little consideration was given to fuel economy, emission pollution was not yet touched on, and the advantages of electronic control systems were not sufficiently recognized. 1967, Bosch introduced the D-Jetronic electronically controlled gasoline injection system, ushering in the spring of the electronic control technology of the engine blossoming of a hundred flowers. Emission regulations and the gasoline crisis, the pressure of these two aspects, coupled with the rapid development of electronic technology, so that since then the development of EFI technology on the fast track. 1981, the introduction of hot-wire air mass flow meter, improve the air-fuel ratio of the control error. Especially the inclusion of microcomputer and the improvement of microcomputer speed and capacity made the control function more and more perfect. Intake gasoline injection evolved from simple multi-point injection technology to sequential injection, further improving emissions and transient performance. With the application of a variety of sensors, the controller is able to understand the operating and environmental conditions of the entire engine, and thus provide intelligent control for different operating modes. The accompanying troubleshooting system can detect the injection system as well as the controller itself, improving reliability of use and ease of maintenance. For these reasons, electronically controlled gasoline injection systems have been rapidly industrialized. In comparison, the gasoline injection fuel system has the following advantages: ① There is no narrow throat in the intake pipe, so there is little resistance to air flow, and the filling performance is good, which is conducive to increasing the output of the engine. ② mixture of the cylinder distribution of uniform performance. ③ The best combustible mixture concentration can be configured accordingly with the changes in automobile operation, ensuring the engine's power, economy, and in particular, reducing the requirements of exhaust pollution. (iv) It has good acceleration and other excessive performance. The main problems that need to be solved in the development of gasoline injection fuel system are the complex arrangement of the system and the high manufacturing cost.　Basic Composition The basic composition of carburetor fuel system can be divided into gasoline supply device (including gasoline tank, gasoline filter, gasoline pump), air supply device (including air filter, air intake muffler, cold and warm air conversion mechanism, etc.), mixture formation device (carburetor), intake and exhaust device (including intake manifolds, exhaust manifolds and muffler).　 Ignition system of automobile engine Composition: The traditional type consists of battery, generator, ignition coil, breaker, spark plug and so on. Ordinary and traditional ignition systems are similar, only with electronic components to replace the breaker. Electronic ignition type is all all-electronic ignition system, completely cancel the mechanical device, by the electronic system to control the ignition moment, including the battery, generator, ignition coil, spark plugs and electronic control system.　Function: In gasoline engine, the combustible mixture in the cylinder is ignited by electric spark, for this reason in the gasoline engine cylinder head is equipped with a spark plug, spark plug head into the combustion chamber. Can be on time in the spark plug electrodes produce an electric spark between all the equipment is called the ignition system.　 Automobile engine cooling system Composition: water-cooled by the water jacket, water pump, radiator, fan, thermostat and other components. Air-cooled by the fan and heat sinks and other components.　Function: the function of the cooling system is to heat parts absorbed part of the heat to be distributed in a timely manner to ensure that the engine works at the most suitable temperature. Lubrication system Composition: by the oil pump, collector filter, pressure limiting valve, oil pipeline, oil filter and other components.　Function: the function of the lubrication system is to deliver a fixed amount of clean lubricant to the surface of the parts in relative motion, in order to realize the liquid friction, reduce friction resistance and reduce the wear of the parts. And clean and cool the surface of the parts. Starting system Composition: by the starter and its ancillary equipment. Automobile engine function: to make the engine transition from a stationary state to a working state, you must first use an external force to rotate the crankshaft of the engine, so that the piston for reciprocating motion, the combustible mixture in the cylinder combustion and expansion of the work, pushing the piston downward movement to make the crankshaft rotation. The engine can run on its own, the work cycle can be carried out automatically. Therefore, the crankshaft began to rotate under the action of external forces to the engine began to automatically idle the whole process, known as the engine start. Completion of the starting process required by the device, known as the engine starting system.　The following single-cylinder engine as an example, the basic structure of the engine, which consists of cylinder 10, piston 8, connecting rod 7, crankshaft 3, cylinder head 11, body, camshaft 16, intake valve 25, exhaust valve 15, valve spring, crankshaft toothed belt pulley and other components. The working chamber of the reciprocating piston internal combustion engine is called the cylinder, and the inner surface of the cylinder is cylindrical. The reciprocating piston in the cylinder is hinged to one end of the connecting rod through the piston pin, and the other end of the connecting rod is connected to the crankshaft, constituting a crank connecting rod mechanism. When the piston reciprocates in the cylinder, the connecting rod pushes the crankshaft to rotate, or vice versa. At the same time, the volume of the cylinder in the continuous from small to large, and then from large to small, so the cycle continues. The top of the cylinder is closed by the cylinder head. The cylinder head is equipped with intake and exhaust valves. Through the opening and closing of the inlet and exhaust valves, the cylinder is inflated and exhaust gas is discharged from the cylinder. The opening and closing of the intake and exhaust valves is driven by a camshaft. The camshaft is driven by the crankshaft through a toothed belt or gear. The parts that make up the cylinder are called the cylinder block and the crankshaft rotates in the crankcase.　 AUTOMOBILE ENGINE 1 - Oil sump 2 - Oil 3 - Crankshaft 4 - Crankshaft timing pulley 5 - Timing belt 6 - Crankcase 7 - Connecting rods 8 -Piston 9 -Water jacket 10 -Cylinder 11 -Cylinder head 12 -Exhaust pipe 13 -Camshaft timing pulley 14 -Rocker arm 15 -Exhaust valves 16 -Camshafts 17 -High voltage wires 18 -Distributor 19 -Air filter 20 -Carburetor 21 -Intake pipe 22 -Ignition switch 23 -Ignition coil 24 -Spark plug 25 -Intake valve 26 -Battery 27 -Flywheel 28 -Starter