The cardan drive shaft is a device that transmits power between two shafts whose relative position changes constantly during the work. Its function is to connect the output shaft of the transmission with the input shaft of the main reducer that is not on the same straight line, to ensure that the power can still be reliably transmitted when the angle and distance between the two shafts change frequently.
The structure and function of the cardan drive shaft are a bit like the joints of human limbs so that the angle between the connecting parts changes within a certain range. In order to meet the angle changes caused by the power transmission, steering adaptation, and up and down jumps during the operation of the car, the drive axle and half shaft of the front-drive car are usually connected to the cardan drive shaft.
However, due to the limitation of the axial dimension, the deflection angle needs to be larger. A single universal joint shaft cannot make the instantaneous angular velocity of the output shaft and the input shaft equal, which easily causes vibration, aggravates the damage of the parts and generates a lot of noise. Therefore, it is widely used in constant velocity universal joint shafts.
In the front-wheel-drive vehicle, two constant velocity universal shafts are used for each half shaft. The universal joint shaft near the transmission axle is the inner universal shaft, and the universal joint shaft near the shaft is the outer universal shaft. In the rear-wheel-drive vehicle, the engine, clutch, and transmission are installed on the frame as a whole. The drive axle is connected to the frame through an elastic suspension.
There is a certain distance between them and needs to be connected. When the vehicle is driving, the uneven road surface will produce jumps, load changes, or position differences between the two assemblies, etc., thereby changing the angle and distance between the transmission output shaft and the input shaft of the final drive of the transaxle.
Therefore, the transmission form of the universal joint shaft of the rear-drive vehicle adopts double universal joint shafts, that is, there are universal shafts at both ends of the transmission shaft, which are used to clamp the two ends of the transmission shaft at an equal angle to ensure the output shaft The instantaneous angular velocity of the drive shaft is always equal on the shaft.
The application of the cardan drive shaft in automobiles mainly includes the following aspects:
① Between transmission (or transfer case) and drive axle: the transmission, clutch, and engine of a general automobile are integrated on the frame, and the drive axle is connected to the frame through the suspension. The angle and distance between the input shaft of the transaxle and the output shaft of the transmission will change due to load changes and the bounce caused by the vehicle running on uneven roads.
② In order to eliminate the influence of shaft coaxiality errors, manufacturing, and assembly errors caused by frame deformation on the power transmission, a universal transmission device must be installed.
③ The semi-axle of the automobile steering axle is segmented. When turning, the angle of the intersection of the two half-axes changes, and a universal shaft should be used.
④ Disconnect the drive axle half shaft: the main reducer shell is fixed on the frame, the axle shell swings up and down, the half shaft is segmented, and the cardan drive shaft must be used. The steering shaft of some cars is equipped with a universal transmission device, which is conducive to the overall arrangement of the steering mechanism.
