Writer: Eric Bearing Limited
1. Working principle of one-way clutch bearing
One-way clutch bearing is a type of bearing, which is characterized by the function of one-way rotation and reverse stop. It is widely used in one-way clutches of washing machines, one-way clutches of automobiles and one-way clutches of electric vehicles.
The one-way clutch bearing unit is generally composed of INA ball bearings and wedge-type one-way clutches. The ball bearings bear the radial force and the wedge bears the torque. The combination realizes the functions of one-way rotation, swing indexing, forward and backward and overrunning. Because of its compact structure, reliable wedging and large torque transmission, it can meet the needs of the main machine functionalization, componentization and small assembly space. INA 81110 TN bearings online , pls click here :
(1) Principle of torque transmission
The special-shaped wedges are evenly distributed on the circumference of the cage, and under the action of the band spring force, the special-shaped wedges are always kept in contact with the inner and outer rings. Because the maximum height of the special-shaped wedge is greater than half of the difference between the inner diameter of the outer ring and the outer diameter of the inner ring, it is often inclined in the working surface of the inner and outer rings. When the outer ring rotates clockwise, the contact surface between the outer ring and the special-shaped wedge generates friction. For the center of each special-shaped wedge, a rightward tilting moment is generated, and the inner and outer rings are strongly meshed with it to transmit torque.
When the outer ring rotates counterclockwise, the center of the various wedges tilts to the left, the inner and outer rings are unwedge, and the outer ring is idling.
(2) Rated torque and idling torque
a. Rated torque: The rated torque of the one-way clutch is measured by the fatigue strength of the meshing surface of the special-shaped roller. Therefore, the repeated rated torque of the one-way clutch refers to the ultimate torque at which the meshing surface cannot produce slippage and harmful plastic deformation, and after 106 times of clutching, there will be no fatigue spalling on the special-shaped wedges and inner and outer ring track surfaces. Since the internal stress generated by the meshing surface is larger on the outer ring side than on the inner ring side, the compressive stress on the inner ring side should be used as a condition when calculating the rated torque.
b. Idling torque: When the one-way clutch is idling, the frictional torque generated by the slip between the wedge and the inner ring is the idling torque.
The wedges in the one-way clutch are attached to the inner ring due to the force of the band spring in the mechanism, so the magnitude of the force of the band spring determines the magnitude of the idling torque. But usually the force of the ribbon spring is very small. In addition, the wedge and the outer ring rotate synchronously. When the outer ring rotates, the wedge is subjected to centrifugal force, so the idling torque is affected by the outer ring speed.
2. Application range of one-way clutch bearings
The suitable range of one-way clutch bearings is divided into three aspects: overrun, indexing, and backstop.
(1) Beyond performance
There are various ways to use the transcendence performance, mainly as the speed conversion of various mechanical devices. The use of a one-way clutch makes the gear shifting device simple and helps reduce costs. Using one motor to input positive and negative speeds in the same direction can realize two-stage speed change.
The input shaft rotates continuously and is converted into intermittent reciprocating motion to complete the intermittent rotation of the output shaft in the same direction, such as in the equipment such as punch roller feeding, printing machinery and packaging machinery.
(3) Anti-reversal mechanism
If the outer ring is fixed and the inner ring is rotated, the inner ring can be prevented from reversing. For example, it is used in elevators, ropeways, etc. Because the one-way clutch can automatically couple and unwedge, it makes the operation simple, the structure is compact, and the transmission mechanism is simplified, so it has been more and more widely used in a variety of transmission systems.