Do you know what a tensioner bearing is?

With the popularization and application of high-position camshafts and overhead camshafts in modern automobile engines, the synchronous chain drive and gear drive of the camshaft have been gradually replaced by the toothed belt drive. At the same time, the transmission of the fuel injection pump of the automobile diesel engine also adopts the synchronous toothed belt. In order to facilitate the installation and adjustment of the synchronous toothed belt, a tensioner bearing is generally used on the loose side of the toothed belt. In more complex toothed belt drives, a fixed idler wheel is often used on the tight side of the toothed belt to increase the wrap angle of the drive wheel or change the position of the toothed belt.

1. Seat plate mounted tensioner bearing
There are two typical designs for tensioner bearings with seat plates. One is a tensioner belt that swings through the seat plate and the seat plate is fixed by a bolt; the other is a tensioner belt that swings through the seat plate and is fixed by a bolt that passes through the inner hole of the bearing. The rolling bearings used in the above two designs are both double-row radial sealed ball bearings. Single-row radial sealed ball bearings are also often used in tensioners mounted on seat plates.

2. Eccentric tensioner bearing
The eccentric tensioner bearing tensions the belt by swinging around the eccentric hole in the support pin, which is fixed by a stud that passes through the eccentric hole and a nut.

3. Lightweight design
The most striking development of the above tensioner bearing is the so-called lightweight design. The development of lightweight design has greatly reduced the mass of the tensioner pulley and effectively reduced the manufacturing cost of the tensioner pulley.

The function of the tensioner bearing is to adjust the tightness of the timing belt, maintain the belt tension, avoid belt slippage, and compensate for the elongation caused by belt wear and aging. Adjust and compensate for the deviation of the center distance of the engine system caused by the machining error of the shaft and the positioning hole. To a certain extent, it can eliminate the abnormal noise caused by the elongation or swing of the belt during the operation of the engine group. Suppress the vibration of the transmission system

Working principle of tensioner bearing

When the engine system is unloaded, the section of the belt that the tensioner pulley is close to will become loose under the condition of poor tension, that is, the tensioner pulley needs to swing rapidly counterclockwise along its own center axis under the action of the torsion spring to compensate for the decrease in the tension on the belt in time; conversely, when the crankshaft is loaded, the section of the belt that the tensioner pulley is close to will be further tightened, and the pulley needs to rotate and swing along its own center axis, and at the same time, the kinetic energy of the belt system is converted into the elastic energy of the torsion spring and stored in the torsion spring for use during unloading. In actual use, the tensioner pulley needs a certain torque to maintain appropriate belt tension, avoid belt slippage, and compensate for the elongation caused by belt wear and aging. When the belt tensioner pulley is running, the moving belt may cause vibration in the tensioner pulley, causing premature wear of the belt and tensioner pulley. For this reason, a resistance mechanism is added to the tensioner. However, since there are many parameters that affect the torque and resistance of the tensioner, and the influence of each parameter is different, the relationship between the various components of the tensioner and the torque and resistance is very complicated. The change of torque directly affects the change of resistance, and it is the main influencing factor of resistance. The main factor affecting the torque is the parameter of the torsion spring. Appropriately reducing the middle diameter of the torsion spring can increase the resistance value of the tensioner.

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