JPH0741957Y2 - Belt auto tensioner device - Google Patents

Description

[Detailed description of the device] [Industrial applications]

This invention is an automatic tensioner device for a power transmission belt used in an engine, for example, a belt for adjusting the tension of a toothed timing belt that is stretched between a crankshaft pulley and a camshaft pulley in an automobile engine. The present invention relates to an auto tensioner device.

[Prior art]

For example, in an automobile engine, an auto-tensioner device shown in FIG. 3 is known as an automatic tensioner device for adjusting the tension by preventing loosening of a timing belt with teeth provided between a pulley of a crankshaft and a pulley of a camshaft. ing. (See JP-A-58-121344) In this type of apparatus, a bracket 51 that rotatably supports an idler 50 is swingably supported by a fixed object such as an engine body 52. This bracket 51 and fixed object 52
A damper 53 is arranged between the and. The damper 53 includes a cylinder 54, a piston 55, and a piston rod 56.
2 consisting of and separated by a piston 55
It has one liquid chamber 57, 58 and a throttle 59 that connects both liquid chambers 57, 58. A coil spring 61 for applying tension to the belt 60 is mounted on the damper 53, and one of the cylinder 54 and the piston 56 is linked to the fixed object 52 and the other is linked to the bracket 51. Therefore, the tension of the belt is kept substantially constant regardless of the ambient temperature, noise at high temperature, jumping at low sound, etc. do not occur, and it is transmitted from the vibrating body such as the belt or the engine to the idler. The damper does not vibrate because vibration is suppressed by the damper.

[Problems to be solved by the device]

However, in the conventional belt auto-tensioner device, each component has to be separately attached to the engine body, which not only requires workability, but also requires tension adjustment of the belt and requires a large installation space. The problem was inherent.

[Means for solving problems]

In order to solve the above problems, the present invention provides a tensioner bearing having a pulley portion abutting a belt on an outer peripheral portion, an eccentric shaft fitted to an inner diameter of the tensioner bearing and having an eccentric hole,
From a bush mounted in the eccentric hole via a first slide bearing, and a spring one-way clutch provided inside the recess formed in the end of the eccentric shaft formed in the end of the eccentric shaft. The spring one-way clutch includes a bush having one end projecting into the recess, a second slide bearing having an axial cut crack fitted on the projecting portion, and a second slide bearing thereof.
A coil spring wound around the plain bearing of which one end is locked to the eccentric shaft, a tensioning spring for the belt is stretched around the eccentric shaft, and the bush is fixed to a fixed object. The eccentric shaft is allowed to swing around the shaft center of the eccentric hole as a fulcrum, and the clutch is activated when the eccentric shaft rotates in the slack direction of the belt.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a vertical sectional view showing an embodiment of an automatic belt tensioner device of the present invention, and FIG. 2 is a front view of the same. The tensioner bearing 1 includes an outer ring 3 having a wide cylindrical pulley portion that abuts on the belt 2, and an inner ring 5 that is fitted to the outer ring 3 and rotatably held via balls 4. An eccentric shaft 6 fitted in the inner ring 5 is provided with an eccentric hole 7 having an axis O ′ eccentric with respect to the axis O of the tensioner bearing 1. A bush 8 is inserted into the eccentric hole 7 and fixed to the engine body (not shown) with bolts or the like. A slide bearing 9 is interposed between the bush 8 and the eccentric shaft 6 to rotatably support the eccentric shaft 6, and
A load generated on the tensioner bearing 1 is applied. One end of the bush 8 projects into a recess provided in one end of the eccentric shaft 6, and a sliding bearing 9'is externally fitted to the projecting portion.
This slide bearing 9'is cracked at one position in the axial direction, and its rigidity in the radial direction is small. Alternatively, the slide bearing 9'may be made of metal, but in order to make the operation of the crank described later smooth, it is preferable that the outer diameter side be metal and the inner diameter side be a synthetic resin having wear resistance and a low friction coefficient. 10 and 10 are plain bearings 9 and 9 '
It is a cover that prevents it from slipping out in the axial direction. A coil spring 11 is wound around the slide bearing 9'and one end of the coil spring 11 is engaged with a locking hole 13 formed in the eccentric shaft 6. A part of the bush 8 protruding into the recess, a slide bearing 9'outer fitted to the bush 8, and a coil spring 11 wound around the slide bearing 9 and having one end engaged with the eccentric shaft 6 make the spring unidirectional. The clutch is constructed. When the coil spring 11 of the spring one-way clutch is twisted in the winding direction, the inner diameter of the coil spring 11 is reduced to tighten the slide bearing 9'and increase the rotational torque. Reference numeral 14 denotes a bracket attached to the outer diameter of the eccentric shaft 6, which swings integrally with the eccentric shaft 6. The spring 15, which is stretched between one end of the bracket 14 and the engine body, swings the bracket 14, that is, the eccentric shaft 6, until the tension of the spring 15 and the tension of the belt 2 are balanced. In this case, the center of swing is the eccentric axis O ', and due to the action of the spring one-way clutch, it is light in the tension direction (B in the figure) of the belt 2 and large in the slack direction (A in the figure). Become.
Therefore, the slack of the belt 2 can be corrected, and when the tension is large, the brake can be gently applied while sliding between the bush 8 and the slide bearing 9 ', so that the belt 2 can always be given an appropriate tension. The slide bearing 9'may not have a single location, but may have two or three sleeves to weaken the rigidity. Plain bearing 9,9 ′
Since the surface of the is slippery, lubricating oil such as grease can be enclosed.

【effect】

With the above-mentioned configuration, the present invention has the effect of making the device compact because the clutch is housed in the recess formed at the end of the eccentric shaft in one direction of the spring. In addition, since the spring one-way clutch is housed in the recess, the clutch is not easily affected by factors such as oil, water adhesion, and rust that change the friction coefficient, and the clutch operation is stable over a long period of time. is there. Further, since a slide bearing having a slit in the axial direction is used as a constituent element of the spring one-way clutch, the spring one-way clutch flexibly deforms when the spring is repeatedly wound. As a result, there is an effect of reducing wear due to repeated winding of the spring.
Further, appropriate tension can always be applied to the belt, and minute vibrations from the engine and the like can be absorbed by the clutch action.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a front view of the same as above, and FIG. 3 is a conventional example. 1 …… Tensioner bearing 2 …… Belt 3 …… Outer ring 6 …… Eccentric shaft 7 …… Eccentric hole 8 …… Bushing 9 …… Sliding bearing 9 ′ …… Axial axial slide bearing 11 …… Spring one-way clutch 14 …… Bracket

Claims (1)

[Scope of utility model registration request] 1. A tensioner bearing having a pulley portion in contact with a belt on an outer peripheral portion, an eccentric shaft fitted to an inner diameter of the tensioner bearing and having an eccentric hole, and a first slide bearing in the eccentric hole. The bush mounted, and a spring one-way clutch provided inside the recess formed in the end of the eccentric shaft, the spring one-way clutch, the bush one end of which protrudes into the recess A second slide bearing having an axial cut crack fitted on the projecting portion, and a coil spring wound around the second slide bearing and having one end locked to the eccentric shaft. Then, a belt tension setting spring is stretched around the eccentric shaft, the bush is fixed to a fixed object, and the eccentric shaft is swingable around the shaft center of the eccentric hole as a fulcrum. When the shaft rotates, There automatic tensioner belt, characterized in that to operate.