Those who have a slight understanding of cars know that many mechanisms in cars use gear transmission. For example, the gearbox of a car is a complex gear transmission mechanism. Other devices include the drive axle, differential, steering gear, and even some electrical components, such as window regulators, wipers, and electronic handbrake. Gear transmission is also used in these devices. Since gears are so widely used and very important in automobiles, how much do we know about them? Today we will talk about the relevant knowledge of gears in cars.
Gear transmission is one of the widely used transmissions in automobiles, which mainly has the following functions:
1. Variable speed: By meshing two gears of different sizes, the speed of the gears can be changed. For example, gearbox gears can reduce or increase the speed transmitted by the engine to meet the driving needs of the car;
2. Torque change: Two gears of different sizes mesh, changing the speed of the gears while also changing the transmitted torque. For example, a car gearbox and the main reducer in the drive axle can change the torque of the car;
3. Direction change: Some car engines operate in a direction perpendicular to the direction of the car's travel, and the direction of power transmission must be changed in order to drive the car. This device is usually the main reducer and differential of a car.
Gear transmission has high transmission efficiency, compact structure, reliable operation of gear transmission, and long service life
Advantages such as stable transmission ratio. Its transmission efficiency can reach 99%, and among commonly used mechanical transmissions, the efficiency of gear transmission is high; Its disadvantage is that compared to belt and chain drives, the manufacturing and installation accuracy requirements of gears are high, and the price is relatively expensive. It is not suitable for transmission with excessive distance between shafts.
In cars, some parts use spur gears and some parts use helical gears. What are their advantages and disadvantages?
When a spur gear engages, it simultaneously enters and exits the mesh along the entire tooth width. Its transmission efficiency is very high, but its disadvantages are poor smoothness, high impact, and noise
The meshing process of helical gears is longer than that of spur gears, and the number of teeth involved in meshing is also greater than that of spur gears. Therefore, helical gear transmission is stable, has strong load-bearing capacity, and has low noise and impact. The main drawback of helical gears is that they generate axial forces when subjected to normal forces on the tooth surface, requiring the installation of thrust bearings, thereby complicating the structure.
The requirements for automotive gears are very high. The tooth body of the gear should have high resistance to breakage, and the tooth surface should have strong resistance to pitting corrosion, wear, and high resistance to gluing, that is, the requirements are: hard tooth surface and tough core. So, the machining process of automotive gears is also very complex, generally including the following processes:
Blanking, forging, normalizing, machining, local copper plating, carburizing, quenching, low-temperature tempering, shot peening, gear grinding (precision grinding)
The gears processed in this way not only have sufficient strength and toughness, but also have high hardness and wear resistance on the tooth surface.