Views: 4 Author: Site Editor Publish Time: 2022-02-21 Origin: Site
An automobile is a non - track non - wired vehicle with four or more wheels driven by its own power plant. A car is generally composed of four basic parts: engine, chassis, body and electrical equipment. Its drive system is composed of clutch, transmission, universal drive shaft device, and the main reducer, differential and half shaft in the drive axle.
Car engine is the engine that provides power for the car, is the heart of the car. Common gasoline and diesel engines are reciprocating piston internal combustion engines, which convert the chemical energy of fuel into the mechanical energy of piston movement and output power.
1. Gasoline and diesel engines
Gasoline engine high speed, low quality, low noise, easy to start, low manufacturing cost; Diesel engine has large compression ratio, high thermal efficiency, better economic performance and emission performance than gasoline engine.
2. Working principle of automobile engine
Four stroke gasoline engine is the air mixed with petrol at a certain ratio into a good mixture of the suction stroke cylinder are inhaled, mixture by compression ignition combustion and generate heat, high temperature and high pressure of the gas on the top of the piston, moves the pistons for reciprocating linear motion, through external output connecting rod, crankshaft, flywheel mechanism.
Four-stroke gasoline engines complete a working cycle in the intake stroke, compression stroke, power stroke and exhaust stroke.
The chassis is composed of four parts: ① transmission system, ② driving system, ③ steering system and ④ braking system. The role of chassis is to support and install the car engine and its components and assemblies, forming the overall shape of the car, and accept the power of the engine, so that the car has movement and ensure normal running.
Automobile transmission system
The power transmission device between the engine and the driving wheel is called the driveline. It should ensure that the car has the necessary traction and speed under various driving conditions, as well as ensure the coordination between the traction and speed changes and other functions, so that the car has good power and fuel economy; It should also ensure that the car can be reversed, and that the left and right driving wheels can meet the differential requirements, and that the power transmission can be smoothly combined or completely and quickly separated as required.
Transmission system includes ① clutch, ② transmission, ③ drive shaft, ④ main reducer, ⑤ differential and ⑥ half shaft and so on. The power transmission device between the engine and the driving wheel is called the driveline.
The clutch is located in the flywheel housing between the engine and the gearbox, and the clutch assembly is fixed on the rear plane of the flywheel with screws. The output shaft of the clutch is the input shaft of the gearbox.
In the process of car driving, the driver can step down or release the clutch pedal according to need, so that the engine and gearbox temporarily separated and gradually engaged, in order to cut off or transfer the engine to the transmission input power.
Transmission is used to change the speed and torque from the engine mechanism, it can be fixed or shift to change the output shaft and input shaft transmission ratio, also known as the gearbox.
It is divided into manual and automatic two kinds, manual transmission is mainly composed of gears and shafts, through different gear combination to produce variable speed and torque; The automatic transmission AT is composed of hydraulic torsional converter, planetary gear and hydraulic control system, which can achieve speed change and torque change through the way of hydraulic transmission and gear combination.
Manual transmission is called manual transmission (REFERRED to as MT), also known as mechanical transmission, that is, the gear must be shifted by hand (commonly known as "block") to change the gear meshing position in the transmission, change the transmission ratio, so as to achieve the purpose of changing the speed.
It has the advantages of simple structure, reliable performance, low cost of manufacturing and maintenance, high transmission efficiency (theoretically more fuel-efficient), in addition, due to pure mechanical control, fast shift response, and can more directly express the will of the driver, so it is more fun to drive, these are the advantages of manual transmission. However, compared with the automatic gearbox, it is cumbersome to operate, and the obvious disadvantage of stumbling when switching gears is irreparable.
Change transmission ratio;
In the same direction of engine rotation, so that the car can run backwards;
Use neutral, interrupt power transmission, so that the engine can start, idle, and facilitate transmission shift or power output;
3. Drive shaft
The drive shaft is composed of shaft tube, telescopic sleeve and universal joint. The telescopic sleeve can automatically adjust the change of distance between the transmission and the drive axle. Universal joint is to ensure the change of the Angle between the two axes of the transmission output shaft and the input shaft of the drive axle, and realize the equiangular speed transmission of the two shafts.
Universal joint is the key part of automobile drive shaft. In the front engine rear wheel drive vehicle, the universal joint drive shaft is installed between the transmission output shaft and the drive axle main reducer input shaft; In front-engine, front-wheel drive vehicles, the drive shaft is omitted, and the universal joint is installed between the front axle axle, which is responsible for both driving and steering, and the wheels.
4. Main reducer
The main reducer is the main part of reducing speed and increasing torque in automobile transmission system. For cars with longitudinal engines, the main reducer also uses bevel gears to change the direction of power.
When the car runs normally, the engine speed is usually about 2000 to 3000r/min. If such a high speed is reduced only by the gearbox, the transmission ratio of the gear in the gearbox needs to be very large, that is, the size of the gearbox will be larger. In addition, the speed drops and the torque inevitably increases, which increases the transmission load of the gearbox and the transmission mechanism after the gearbox.
Therefore, in the power to the left and right driving wheel before the differential set up a main reducer, can make the main reducer in front of the transmission parts such as gearbox, transfer, universal transmission device transmission torque is reduced, can also make the gearbox size, quality reduction, control effort.
The automobile differential can make the left and right (or front and rear) driving wheel to achieve different rotation speed of the mechanism. It is mainly composed of left and right half shaft gears, two planetary gears and gear frame.
Function is when the car turns or travels on uneven roads, so that the left and right wheels roll at different speeds, that is, to ensure that both sides of the driving wheels for pure rolling motion. Differential is to adjust the left and right wheel speed difference and device.