Do you all know what kinds of universal joints are? The following Xianji network Xiaobian will give you a brief introduction to the classification of universal joints. According to whether universal joints have obvious elasticity in the torsion direction, they can be divided into rigid universal joints and flexible universal joints. The steel universal joint can be divided into three kinds: non-uniform speed universal joint (commonly used for the cross shaft type), quasi-uniform speed universal joint (such as double type universal joint) and uniform speed universal joint (such as ball cage type universal joint).

Classification of universal joints

Unconstant velocity universal joint

The cross shaft type rigid universal joint is widely used in the automobile with different speed universal joint. It allows the larger intersection Angle between two adjacent shafts to be 15゜ ~ 20 ". The cross shaft type universal joint as shown in the figure below consists of a cross shaft, two universal joint forks and four needle roller bearings. The holes on the forks 1 and 3 of the 20,000-way joint are respectively sleeved on the two pairs of journal of the cross shaft 2. In this way, when the driving shaft rotates, the driven shaft can rotate along with it and swing in any direction around the center of the cross shaft, so as to adapt to the need of the change of Angle and distance at the same time. Needle roller bearing 5 is arranged between the journal of the cross shaft and the fork hole of the universal joint, and the outer ring of the needle roller bearing is axially positioned by the clasp ring. In order to lubricate the bearing, the cross shaft is generally provided with an oil nozzle and an oil path to the journal. Lubricating oil can be injected from the nozzle to the needle roller bearing of the journal of the cross shaft.

The cross shaft rigid universal joint has the advantages of simple structure and high transmission efficiency, but it can not transfer constant angular speed under the condition that the Angle between two shafts α is not zero.

When the following two conditions are met, the transmission from the output shaft to the drive axle can be achieved.

structure

Lubricate sealing, inside and outside retaining ring positioning

The working principle of

1. When the driving fork is in a vertical position and the cross axis plane is perpendicular to the driving shaft. At this point, the linear velocity of the connecting point A between the driving fork and the cross shaft and the connecting point B between the driven fork and the cross shaft are equal in the plane of the cross shaft. (Velocity projection of the driven fork to the cross-axis plane).

2. When the driving fork is in a horizontal position and the cross axis plane is perpendicular to the driven axis. (Velocity projection of the active fork to the cross-axis plane).

3. The relationship between the rotation Angle and speed of the master and slave moving shafts.

The greater the Angle of the two shafts, the greater the speed, the worse the unequal speed of the drive shaft.

Inequality of cross shaft universal joint: it refers to the angular speed of the driven shaft is not uniform in a week. If the drive shaft rotates at an equal angular speed, then the driven shaft is fast or slow, that is, the transmission of a single cross shaft universal joint is not uniform when there is an included Angle.

The conditions of double cross shaft universal joint to achieve constant speed transmission between two shafts (the output shaft of the transmission and the input shaft of the drive axle) :

(1). The included Angle between the two shafts of the first universal joint is equal to that between the two shafts of the second universal joint (design guarantee);

(2). The driven fork of the first universal joint is in the same plane as the driving fork of the second universal joint (guaranteed by the assembly).

Because the relative position of the transmission and the main reducer is constantly changing when the non-independent suspension is used, the first condition is difficult to meet, and the non-equivelocity can only be as small as possible.

Constant speed condition of cross shaft double universal joint transmission: between the output shaft of the transmission and the input shaft of the drive axle, the double universal joint transmission is used, then the unequal speed effect of the first universal joint is likely to be offset by the unequal speed effect of the second universal joint, so as to realize the equiangular speed transmission between the two shafts. According to the kinematics analysis, two conditions must be satisfied to achieve this goal: (1) The included Angle α1 between the two axes of the first universal joint is equal to the included Angle α2 between the two axes of the second universal joint; ② The driven fork of the first universal joint and the driven fork of the second universal joint are in the same plane. The first condition can only be realized through the overall layout design of the vehicle and the guarantee of the general assembly process when the driving wheel adopts the independent suspension.

Isochronous condition of cross shaft universal joint:

(1) Adopt double universal joint drive;

(2) The included Angle 1 between the two shafts of the first universal joint is equal to the included Angle 2 between the two shafts of the second universal joint;

(3) The driven fork of the first universal joint and the active fork of the second universal joint are in the same plane.

The common quasi-constant speed universal joint has two kinds of double coupling and three pin shaft, their working principle and double cross shaft universal joint to achieve constant speed transmission principle is the same.

The double universal joint is actually a set of double cross shaft type universal joint constant speed transmission device which reduces the length of the transmission shaft to a smaller size. The double fork is equivalent to the transmission shaft and the two ends of the universal joint fork in the same plane. When the Angle of intersection between the output shaft and the input shaft is small, the point of intersection of the two axes on the circular arc is very close to the above central perpendicular, so that the difference between α1 and α2 is very small, and the angular velocity of the two axes is close to the same, so it is called the quasi-constant velocity universal joint of the dual type.

Double and triple pin type

Duplex:

Principle: according to the double cross shaft universal joint to achieve constant speed transmission principle. When relative cardan universal joint fork 2 1 within an Angle when swinging, double fork is driven deflection Angle accordingly, also make the two cross connect with the axis of the two cardan shaft center Angle difference is very small, so that the two shaft angular velocity is close to equal, in the range of allowable difference, duplex universal joint has a constant speed.

Advantages: allowing a large Angle between the shaft, simple structure, convenient manufacturing, reliable work, a large Angle up to 50 °

Dual-type universal joint is used for steering drive axle. There can be no indexing mechanism, but it must be structurally guaranteed that the center of the double-type universal joint is located at the intersection point of the main pin axis and the half-shaft axis to ensure constant speed transmission.

Three-pin type universal joint:

Evolved from the double universal joint.

Advantages: allow two adjacent axles to have a larger Angle of intersection, up to 45°, in the steering drive axle can make the car to obtain a smaller turning radius, improve the mobility of the car.

Disadvantages: occupied a larger space.

Drive shaft position 0°~90°90°~180°180°~360°

When the driven fork leads the active fork at 45°, it reaches the maximum when the driven shaft accelerates first and then decelerates. When the driven fork lags the active fork at 135°, it reaches the maximum when the driven shaft decelerates first and then accelerates at 180°

Spherical roller type universal joint:

The spherical roller mounted on the three pin shafts integrated with the universal joint shaft can move along the three axial grooves of the tubular body connected with the shaft 1 of the other ten universal joint to play the role of a telescopic spline. Torque can be transferred between the three spherical rollers and the groove wall of the cylinder. In structure, the axes of the three spherical rollers which are equally divided along the circumference should always be located or approximately located on the bisector plane of the Angle between the two axes of the universal joint. The universal joint allows an Angle between shafts up to 43° and is easy to manufacture.

Constant velocity universal joint

Passenger car commonly used constant speed universal joint has the ball cage type universal joint and the ball fork type universal joint, also useful free three pivot universal joint.

The structure of ball cage universal joint is shown in the following figure. The inner spline of the star sleeve 7 is connected with the driving shaft 1. There are six arc-shaped grooves on its outer surface to form an inner raceway. The inner surface of the spherical shell 8 is provided with six corresponding curved grooves to form an outer raceway. The six balls 6 are each mounted in a space facing by the six sets of inner and outer raceways and confined to the same plane by cage 4. Power from the drive shaft 1 (and star sleeve) through the steel ball 6 to the spherical shell 8 output.

Ball fork universal joint, ball cage universal joint

Basic principle: structurally, the force transmission point of the universal joint is always located on the plane of the intersection point of the two axes during its working process.

Ball fork universal joint:

Advantages: simple structure, allowing a larger intersection Angle of 32°~33°;

Disadvantages: pressure assembly, disassembly and assembly is not convenient, steel ball and curved groove unit pressure is large, wear fast; Only two steel balls transfer force; when reversed, the other two balls transfer force.

Ball cage type universal joint:

Advantages: the larger intersection Angle of the two shafts is 42°, no matter the direction of transmission, the six steel balls all transfer force. Compared with the ball fork type universal joint, it has strong bearing capacity, compact structure and convenient disassembly and assembly.

If the inner and outer raceway adopts the barrel shape, it becomes the telescopic ball cage type universal joint, eliminating the sliding spline in the transmission device, and the sliding resistance is small, and it is suitable for the broken drive axle.

Classification of universal joints

Flexible universal joint

Flexible universal joints rely on the elastic deformation of elastic parts to ensure that no mechanical interference occurs in the transmission between two shafts.

It is generally used in universal transmission where the Angle between two shafts is not more than 3°~5° and the axial displacement is small.

Advantages: eliminate the influence of manufacturing and installation error and frame deformation on transmission; Absorbs impact, attenuates torsional vibration; Simple structure without lubrication.