Automotive drive system knowledge

carThere is a very important part on it, called a universal joint.Gimbal andtransmission shaftThe combination is called universal joint transmission.On a front-engine rear-wheel drive vehicle, the universal joint transmission is installed intransmissionOutput shaft andDrive axleBetween the input shafts of the main reducer; and the front-engine front-wheel drive vehicle omits the transmission shaft, and the universal joint is installed in the drive and steeringFront bridgeHalf shaftAnd between the wheels.

So, what role does the universal joint play in the car?

The car is a moving object. In a rear-drive car, the engine,clutchIt is installed on the frame as a whole with the transmission, and the drive axle is connected to the frame through elastic suspension. There is a distance between the two, which needs to be connected. During the operation of the car, the uneven road surface will cause bounce, load changes, or the difference in the installation position of the two assemblies, will cause the angle and distance between the transmission output shaft and the input shaft of the drive axle final reducer to change. Therefore, it is necessary to use a "" device to solve this problem, so there is a universal joint.

By the same token, off-road vehicle transmissions areSplitterIn between, the universal joint is needed as a "joint" between the front-drive steerable drive axle and the half shaft. The structure and function of the universal joint is a bit like the joints on the limbs of the human body. It allows the angle between the connected parts to change. But it is different from the movement form of the limb joints, it only allows the angle to change within a certain range.

Universal joints have cross-shaft rigid universal joints, quasi-constant velocity universal joints (double coupling and three-pin shaft type), constant velocity universal joints (ball fork type and ball cage type), disturbing universal joints .

At present, the most widely used common universal joint in rear-drive cars is composed of basic parts such as universal joint forks and cross shafts. The cross shaft is assembled on the universal joint fork for connection. The shaft head of the cross shaft is equipped with a needle bearing. When the shaft head is connected to the universal joint fork, the cross shaft and the universal joint fork can rotate relative to each other. There is a multi-angle change. The spline connection on the universal joint fork can do a small amount of axial movement, so that it meets the needs of simultaneous changes in the angle and distance.

A single universal joint cannot equalize the instantaneous angular velocities of the output shaft and the shaft input shaft, which may easily cause vibration, aggravate the damage of the mechanical parts, and generate a lot of noise. Therefore, the universal joint transmission form of rear-drive cars adopts double universal joints, that is, there is a universal joint at each end of the transmission shaft. Its function is to make the angle between the two ends of the transmission shaft equal, and to ensure that the output shaft and the shaft enter the shaft. The instantaneous angular velocity is always equal.

In order to meet the angle changes caused by the up and down jumps generated by power transmission, steering and car running, universal joints are also commonly used between the drive axle of the front drive car and the axle shaft and the wheel axle. Due to the limitation of the axial size, the required deflection angle is relatively large, and ordinary universal joints are difficult to handle. Therefore, various constant velocity universal joints are widely used. In general front drive vehicles, each half shaft uses two constant velocity universal joints. The universal joint near the transaxle is the inner universal joint of the half shaft, and the outer universal joint of the half shaft is near the axle. Among various constant velocity universal joints, the common one is the ball-cage universal joint, which uses six steel balls to transmit force. When the driving shaft and the driven shaft are at any angle, the steel balls are located at the intersection of the two circles. , Which is located on the bisecting plane of the intersection angle of the two shafts, so as to ensure the angular velocity transmission of the main and driven shafts.