Working principle and structure design of one-way bearing

The so-called one-way bearing refers to a bearing that can rotate freely in one direction and is locked in the other direction. One-way bearings are also called overrunning clutches, but they are named according to different industries and different functions. The metal shell of the one-way bearing contains many rollers, needle rollers or balls, and the shape of its rolling seat (cavity) makes it only roll in one direction, and produces great resistance in the other direction ( The so-called "one-way").

The working principle of one-way bearing:

The principle of general one-way bearings is the clamping principle. The working surface where the rolling elements are used for clamping is a slope. When the rolling elements rotate along the bearing, they are downhill, and when they are reversed, they are uphill. There are irregular blocks. The form of one-way clutch is also the same working principle.

One-way bearing structure design:

1. Slope and roller design

The slope and roller type one-way clutch is basically composed of an outer ring with a cylindrical inner diameter, an inner ring with a slope, and a set of rollers that respectively bear spring force and are always in close contact with the inner and outer rings. This arrangement essentially ensures immediacy of overrun speed and guarantees immediate actuation capability as long as rotation of one of the raceways in its direction of motion affects the other.

2. Wedge design

This wedge type one-way overrunning clutch is generally made up of inner ring, outer ring, wedge group, wedge cage, powerful spring and bearing. Wedges transmit force from one raceway to the other by wedging between the inner and outer rings. The wedge has two diagonal diameters, (i.e. the distance from one corner of the wedge to the other diagonal) one of which is larger than the other. Wedging occurs when the inner and outer rings rotate relative to each other, forcing the wedge to have a greater vertical position over a larger cross-section.

3. The self-locking angle wedge function mainly depends on the wedging and self-locking angle of the wedge between the inner and outer rings.

The basic concept of the wedge one-way clutch requires that the friction coefficient of the wedge is related to the sudden torque generated by the inner ring in the driving direction, and this friction value must be greater than the tangent of the self-locking angle. If conditions are not safe, wedging will not occur.

The self-locking angle is determined by the structure of the wedge, and the points on the inner and outer rings are respectively connected with the wedge. The wedge is designed with a very low initial self-locking angle to ensure absolute engagement from the start. As the torque increases, a radial force is exerted on the wedge that deflects the wedge raceway, causing the wedge to roll to a new position. Wedges are often designed to have a progressively increasing self-locking angle, as it goes from the overriding position to the maximum load bearing position. A relatively large self-locking angle can reduce the radial force generated by the wedge, thus allowing a large torque to be transmitted as long as the elongation and Brinell hardness limit requirements are met.