Differential

The car differential is the main component that drives the car. Its role is to transmit power to both sides of the axle, while allowing both sides of the axle to rotate at different speeds, to meet both sides of the wheel as far as possible in the form of pure rolling for unequal travel, reducing tire and ground friction.

When the car is turning, the wheel's trajectory is a circular arc. If the car turns left, the center point of the arc is on the left. At the same time, the right side of the wheel walks longer than the left side wheel to balance this difference. The left wheel is slower, the right wheel is faster, and the difference in distance is compensated by different speeds.

If the rear axle is made in one piece, the difference in speed between the two wheels cannot be achieved. That is, automatic adjustment cannot be made. To solve this problem, as early as a hundred years ago, Luis Reno, the founder of Renault Motors in France, designed the differential.

The common differential consists of planetary gears, planetary carrier (differential case), and semi-axle gears. The power of the engine enters the differential through the drive shaft, directly drives the planetary carrier, and then the left and right two half shafts are driven by the planetary wheels to drive the left and right wheels, respectively. The design requirements of the differential are to be satisfied: (left half shaft speed) + (right half shaft speed) = 2 (planetary wheel speed). When the car goes straight, the rotational speeds of the left and right wheels and the planetary carrier are equalized. In balance, the balance of the three cars is destroyed when the car turns, causing the inner wheel speed to decrease and the outer wheel speed to increase.

This adjustment is automatic and involves the “minimum energy consumption principle”, which means that all objects on Earth tend to use the least energy. For example, when putting a bean in a bowl, the beans will automatically stay at the bottom of the bowl and never stay in the bowl because the bowl bottom is the lowest energy position (bit energy). It automatically selects the rest (minimum kinetic energy) Will continue to exercise. In the same way, when the wheels turn, they will automatically tend to the lowest energy consumption and automatically adjust the rotation speed of the left and right wheels according to the turning radius.

When turning, due to the phenomenon of slipping on the outer wheel, the inner wheel has a slip phenomenon. The two driving wheels will then generate two additional forces in opposite directions. Due to the “minimum energy consumption principle”, the two wheels will inevitably be caused. The rotation speed is different, thus destroying the balance relationship between the three, and through the half shaft reflected on the side gear, forcing the planetary gear to produce rotation, so that the speed of the outer half shaft is accelerated, the speed of the inner half shaft is slowed, thereby realizing the rotation speed of the two wheels difference.