1, explanation
Function
crank drive is to provide a combustion properties of the fuel after the combustion gas acts on the piston crown into the expansion pressure of the torque of crankshaft rotation, constantly output power. Crank drive engine operating cycle to achieve complete conversion of the primary energy of the moving parts. In the power stroke, the piston reciprocates it will heat the fuel combustion, the crankshaft rotational motion into mechanical energy, the external output power; in other stroke, rely on the rotational inertia of the crank and the flywheel, a piston rod driven by up and down movement, is next time do work to create the conditions.
2, action
Crank two mechanism is a Fuel Combustion after applied to the of the piston on top of the expansion pressure into promote crankshaft rotational the torque , out output power .
3. The composition of
Usually a crank and connecting rod mechanism sets the body , of the piston is connected bar group and crankshaft flywheel component three components
4, the body component
body the main group of The cylinder block , The cylinder head , Cylinder head gasket , crankcase [ 123] and sump and other components. The cylinder block
The cylinder block is an assembly of various agencies and the matrix system of the engine, the engine is one of the most important member. The cylinder block has a cylinder and a water-cooled air-cooled cylinder block.Usually a water-cooled cylinder block cast in one piece with the crankcase. An upper portion of a cavity of the cylinder block took all of the cylinders, the cylinders constituting the surrounding water jacket interconnected. The lower half is used to support the crankshaft of the crankcase.
The cylinder block has an inline, V-shaped, and horizontally opposed three forms, common line and two kinds of V-shape in the car. A lower portion of the cylinder block has a structure of general formula, gantry, and three forms of tunnel air-cooled cylinder block and crankcase split structure, the cylinder block and the crankcase cast separately and then assembled together. The outer surface of the cylinder block and the cylinder head has many fins cast to ensure adequate cooling, the material is generally gray cast iron cylinder, to improve the wear resistance of the cylinder, sometimes with small amounts of alloying elements such as nickel, molybdenum, chromium and phosphorus in cast iron Wait. Actually, however, in addition to the cylinder wall surface cooperating with the piston, the other part is not high wear resistance. For economy in material, widely used in the cylinder insert into the cylinder liner to the cylinder working surface is formed. Thus, the available wear liner is preferably an alloy cast iron or alloy steel, to extend the service life of the cylinder, the cylinder and the lower price available ordinary cast iron or aluminum alloy material. Cylinder liner dry and wet two.
Dry the outer surface of the cylinder not in direct contact with the cold water, the wall thickness is generally 1 ~ 3mm. The outer surface of the inner surface of its cylinder liner assembly interference fit.
wet cylinder outer surface in direct contact with cooling water, the cooling effect. Liner wall thickness than dry, usually 5 ~ 9mm.
The cylinder head
The main role of the cylinder head is closed the upper portion of the cylinder, and of the piston The top and cylinder together form of the combustion chamber [123 wall] . Usually a water-cooled engine cylinder head cooling water jacket is cast within the upper end of the lower end surface of the cylinder head water jacket facing a corresponding communication, the use of water to cool the combustion chamber walls and other circulating high temperature portion; air-cooled engine cylinder head casting has many fins, by increasing the cooling area to reduce the temperature of the combustion chamber.
of the cylinders of the engine intake and exhaust valves should cover housing and the intake conduit an exhaust passage holes and the like. Gasoline Engine cylinder head should have the plug hole, while the diesel engine is provided with mounting holes do injector.
Cylinder head gasketwith the cylinder block between the cylinder head and the cylinder liner, its role is to ensure the sealing between the cylinder head and a cylinder block, a combustion chamber to prevent leakage, leaking water jacket.
sumpprimary role is to store the oil sump and the crankcase is closed. Sump force is very small, typically using a thin steel stamping.
5, the piston rod group
of the piston rod the group consisting of major parts of the piston, piston rings, piston pins, connecting rods and other components.
Function of the piston of the piston is
The cylinder head , of the cylinder wall common components of the combustion chamber and receiving cylinder gas pressure through of the piston pin the biasing force transmitted to the links to facilitate rotation of the crankshaft.
of the piston head can be divided into three parts, the annular groove portion and the skirt portion.is an integral piston head of the piston of the combustion chamber, the shape depending on the form of the combustion chamber. Common piston head has a flat-top shape, a concave and convex-top-top.
is mounted in the piston ring groove piston ring groove. Gasoline is generally 2 to 3 by a ring groove, above 1 ~ 2 gas ring for mounting, sealing the cylinder; for mounting a lowermostOil ring. In the bottom surface of the oil ring drilled with a plurality of radial return hole, when the piston moves downward, the oil ring to the cylinder wall was scraped off the excess oil back into the oil pan through an oil return hole. If the temperature is too high, top ring prone to carbon deposition, overheating stuck phenomenon.
of the piston skirt portion of the piston skirt serves as a guide.
pistonpiston mounted in the piston ring groove for sealing the clearance between the piston and the cylinder wall to prevent the blow-by gas, while the piston reciprocates will McNair.
piston rings and an oil ring into two kinds of gas. of the piston pin
of the piston pin connecting the piston and the role of connecting rod small end, and suffered gas forces the piston rod to pass.The piston pin is generally a hollow cylinder, sometimes made at equal strength requirements section of the tubular structure.
of the piston pin is generally used for producing low-carbon steel or low carbon alloy.
all-floating piston pin and semi-floating pin connected to the piston bore and the connecting rod small end bush hole. Connection with full floating piston pin can rotate freely within the bore; semi-floating connection, interference fit between the pin and the connecting rod small end, the work does not rotate relatively; between the pin and the piston pin bore is clearance fit.
linksof the piston rod is subjected to the action of force to the crankshaft, and the reciprocating motion of the piston into rotary motion of the crankshaft.
by a rod linkage member, the cover rod, rod bearing and connecting rod bolt and other parts, the link rod body into the cap connecting rod small end, a shaft and a connecting rod the bulk.
for mounting the piston rod small end pin, is connected to the piston. The shaft usually made of “I” or “H” shaped cross section, in order to reduce the mass of the premise of meeting the strength and stiffness requirements.
connected to the connecting rod of the crankshaft connecting rod journal. Generally made split, with the shaft rod cap called half cut, both integrally connected by the connecting rod bolts.
mounted on the connecting rod bearing in the connecting rod housing hole, and together with the connecting rod is journaled on a crankshaft, the engine is one of the most important sub-fit. Less common running mainly white gold alloy, copper-lead alloy and aluminum-based alloys.
6, the crankshaft flywheel group
Crankshaftby a crankshaft and a flywheel set of primary flywheel and various other parts of the role and the role of the flywheel and various other parts and accessories.
crankshaft is one of the most important parts of the engine.
which acts to set the piston rod of the gas coming into force of the external output rotational torque of the crankshaft, and the drive mechanism of the engine valve and the other auxiliary machines work.The main front of the crankshaft for driving the valve means subsidiary bodies, pumps and fans, the front end of the shaft is mounted with a timing gear (or belt wheel), the fan and pump pulley, twisting Save starting vibration and the like claws.
crankshaft rear flange structure employed for mounting the flywheel.
main journal and the connecting rod journal is the most critical engine sub-sliding fit, generally subjected to a surface hardening, the journal at the fillet and the like must be reinforced rolling process etc., to improve its anti- fatigue strength.
axial positioning of the crankshaft generally use the thrust pad sheet or cuff, positioning means mounted on the main bearing at the front end or the first channel at a middle bearing.
is generally used in high strength crankshaft, impact toughness and good wear resistance in high-carbon steel, high carbon steel or high-strength forged or cast ductile iron.
crankshaft must be dynamic balancing test, imbalance of the crankshaft, which often biased towards one side or the counterweight crank drill part quality, required to reach equilibrium before assembly.
flywheelis a flywheel moment of inertia of a large disc, there is a pressure on the outer periphery of the ring gear meshing with the drive gear of the starter, the starter for the engine used.
on the flywheel usually engraved marks the first cylinder ignition timing, the ignition timing in order to calibrate.
flywheel multi-cylinder engine tests must be balanced with the crankshaft. In order to ensure that the assembly does not destroy the relationship between the flywheel and the crankshaft in the disassembly process, using the positioning pin or bolt asymmetrical arrangement, the installation should be noted.
7, the function of the toggle mechanism
Function crank drive is provided after the combustion properties of the fuel to the combustion gas acts on the piston crown inflation pressure into a torque rotating crankshaft, an output power continuously.
(1) the pressure of the gas in the crank shaft torque becomes
(2) The reciprocation of the pistons of the rotational movement of the crankshaft becomes
8. The composition of [123 ]
(1) Body group: a cylinder block, a cylinder state and the cylinder head, crankcase and sump
(2) a piston rod Group: piston, piston rings, piston pins, connecting rod [123 ] (3) a crankshaft flywheel component: crankshaft flywheel