What is the function and principle of the car differential

Update:12-12-2020
Summary:

The invention of the differential is because when the c […]

The invention of the differential is because when the car is turning, the path taken by the outer wheels is larger than the path taken by the inner wheels. Therefore, if the car wants to turn smoothly and accurately, it needs a device that can convert and allow the inner and outer wheels. Rotate at different speeds to compensate for the difference in distance with different speeds. The earliest differential was invented on a guide car in China to provide power to the doll, but it did not appear in large numbers until the car in the industrial age was universal, and the power was also output from the engine to the wheels in reverse.
The inside of the ordinary differential is a planetary gear mechanism, which includes two planetary gears and two half-shaft gears connected to the transmission shaft. These four gears are arranged in an internal housing of the differential and are mutually connected. Each gear bites together, each gear bites the other two gears (each side gear bites two planetary gears, and each planetary gear bites two side gears), so as long as one of the gears rotates, it is bound to Will cause the other three gears to rotate together, and when one of the side gears rotates in a certain direction, the side gear on the other side will inevitably rotate in the opposite direction. This phenomenon can be proved through experiments. When the wheel is suspended, turning the wheel on one side in one direction will inevitably cause the wheel on the other side to rotate in the opposite direction.
When the car is driving in a straight line, because the resistance on the left and right driving wheels is roughly the same, the output shaft of the engine (that is, the input shaft of the differential) will drive the left and right side gears. At this time, due to the resistance on both sides Consistent, so the two planetary gears in the middle follow the rotation of the side gears on both sides without rotating. When the vehicle makes a turn, the distance traveled by one wheel will be shorter than that of the other side, that is, the resistance generated will become greater than the other side, which means that the planetary gear will turn this side wheel more Laboriously, this balance is disrupted, forcing the planetary gears to rotate and speeding up the outer wheels, so that the vehicle can turn smoothly.
Since the differential allows the wheels on both sides to rotate at different speeds, when one of the driving wheels of the vehicle slips, or when one wheel is off the ground due to violent driving, the full power of the differential is equal to torque. It will be transmitted to the slippery axle, causing the wheel on one side of the slip to spin quickly, while the wheel on the other side loses driving force, which will make the vehicle stuck and lose its maneuverability.
Although the differential solves the problem of difficult turning of vehicles, for vehicles with off-road requirements or competition requirements, the inability to limit slip will lose the passage and maneuverability of the vehicle, so a limited slip differential and differential lock are required , To meet the needs of vehicle competition and off-road.

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