The engine is the power source of the automobile. Automotive engines are mostly thermal power plant, referred to as the heat engine. The heat engine is converted into mechanical energy by the state change of the working fluid.

Engine to provide power for the car. Engine is also widely used in transport machinery, agricultural machinery, construction machinery and power generating units and other aspects. A wide range of engines, of which the four - stroke engine is the most common one.

The four stroke engine is a reciprocating piston type internal combustion engine, according to the different types of fuel used, divided into three types of gasoline engines, diesel engines and gas fuel engines. Piston type internal combustion engine using gasoline or diesel as fuel, respectively, as gasoline engine or diesel engine. Piston type internal combustion engine using natural gas, liquefied petroleum gas and other gas fuel is called gas fuel engine. Gasoline and diesel are petroleum products, is the traditional fuel automobile engine. Non petroleum fuels are called alternative fuels. The engine, which is used as alternative fuel, is called alternative fuel engine, such as ethanol engine, hydrogen engine, methanol engine, etc..

Basic terms

(1) the work cycle (cycle) - (intake) by the intake and compression (compression), work (P four stroke engine and exhaust ower) (exhaust) closed process of four working process.

(2) the upper and lower ends of the piston top away from the center of the crankshaft is the top dead point (TopDeadCenter, TDC); the center of the piston from the nearest point of the center of the lower end (BottomDeadCenter, BDC). The piston moves from one point to another in a process called stroke (stroke).

(3) the piston stroke (pistonstroke) - the distance between the upper and the lower S is called the piston stroke. The turning radius of the crankshaft R is called the crank radius. It is clear that every 1 weeks of the crankshaft, the piston moves 2 piston strokes. For the cylinder center line through the crankshaft rotary center of the internal combustion engine, there are S=2R.

(4) the capacity of the cylinder - the volume of the cylinder between the upper and lower ends of the cylinder is called the working volume of the cylinder (sweptvolume),

(5) engine displacement - the sum of all cylinders in the engine is called the engine displacement (enginedisplacement),

(6) the volume of the combustion chamber piston is located at the top end, the piston top surface of the cylinder head above the bottom surface formed by the space known as the combustion chamber, whose volume is called the combustion chamber volume (clearancevolume), also called compression volume,

(7) the total volume of the cylinder - the sum of the working volume of the cylinder and the volume of the combustion chamber, and the total volume of the cylinder,

(8) the ratio of the compression ratio - the ratio of the cylinder to the combustion chamber is called the compression ratio (compressionratio), and the compression ratio indicates the degree of compression of the gas in the cylinder when the piston moves from the down stop to the top dead point. The greater the compression ratio, the higher the gas pressure and temperature in the cylinder at the end of compression. Gasoline engine compression ratio is generally 8 ~ 11.

(9) the operating condition of the internal combustion engine at a certain time, the effective power of the output of the internal combustion engine and the speed of the crankshaft. Crankshaft speed is the internal combustion engine speed (speed).

(10) the ratio of the effective power of the internal combustion engine at a certain speed and the maximum available power that can be emitted at the same speed is referred to as the load rate, expressed as a percentage. Load rate is usually referred to as the load (load).

Historical development

The engine is the power source of the automobile. Automotive engines are mostly thermal power plant, referred to as the heat engine. The heat engine is converted into mechanical energy by the state change of the working fluid.

Reciprocating piston type internal combustion engine used in the main fuel is gasoline (gasoline) or diesel (diesel). Because of the different nature of gasoline and diesel, there are differences in the working principle and structure of the engine.

Reciprocating piston four stroke gasoline engine is the German Otto (NicolausA.Otto) in the atmospheric pressure based on the engine, in 1876 and put into use. As a result of the intake, compression, expansion and exhaust stroke of four, the thermal efficiency of four stroke engine motivation increased from atmospheric pressure type engine from 11% to 14%, and the quality of the engine was reduced by 70%.

1892 German engineer Diesel (RudolfDiesel) invented the compression ignition engine (ie diesel engine), the realization of the history of the second major breakthrough in the internal combustion engine. Because of the high compression ratio and expansion ratio, the heat efficiency is 1 times higher than that of the other engines. In 1956, the German Wankel (F.ankel) invented the rotor engine, so that the engine speed has been greatly improved. In 1964, the German NSU company for the first time the rotor engine installed in the car.

In 1926, the Swiss Bush (A.Buchi) put forward the exhaust gas turbo theory, the use of exhaust emissions from the engine to drive the compressor, to the engine booster. After 50s, the exhaust gas turbocharger technology began to be applied in the car with the internal combustion engine, so that the engine performance has been greatly improved, becoming the third major breakthrough in the history of the development of internal combustion engine.

In 1967, Germany's BOSCH (Bosch) Company for the first time by the electronic computer controlled gasoline injection system (ElectronicFuelInjection, EFI), to create an electronic control technology in the application of the history of the car engine. After 30 years of development, the engine management system (EngineManagementSystem, EMS), which is the core of the electronic computer, has gradually become the standard configuration of the car, especially the car engine. Due to the application of electronic control technology, engine emissions, noise and fuel consumption significantly reduced, improving the power performance, becoming the fourth major breakthrough in the history of the development of internal combustion engine.

According to the engine during a work cycle