JPH0743516Y2 - Friction type auto tensioner resonance prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an automatic tensioner that automatically adjusts the tension of a timing belt of an internal combustion engine. Particularly, it relates to a means for preventing and reducing resonance of the tensioner in a friction type auto tensioner.

[Conventional technology]

The internal combustion engine is provided with a power transmission mechanism using a toothed timing belt that uses a part of the output in order to drive the camshaft and the oil pump. The belt tension changes due to differences in engine warm-up conditions during operation, and the belt itself stretches, causing slippage and skipping, and generating a humming noise when the tension is excessive. Therefore, it is necessary to keep the tension at a proper level in order to prevent it. For this reason, a friction damping type belt tension automatic adjusting device (friction type automatic tensioner) has been devised.

For example, in Japanese Utility Model Laid-Open No. 63-3550,
An automatic adjusting device (hereinafter referred to as an auto tensioner) having the following configuration is disclosed. That is, in order to drive the valve train of the internal combustion engine as shown in FIG.
10, a predetermined tension is applied to the toothed timing belt 1 so that the camshaft side cam pulley 3 and the oil pump pulley 4 are driven by the crankshaft side timing pulley 2 and the back side of the timing belt 1 is provided. The idle pulley 5 and the auto tensioner pulley 11 are arranged in the
The belt 12 is pressed by a constant urging force by 12 to give a predetermined tension to the belt.

A sectional view of the auto tensioner 10 is shown in FIG. In the auto tensioner 10, 11 is the auto tensioner pulley,
Reference numeral 13 is a shaft of the pulley 11, and the pulley 11 rotates around the pulley shaft 13 via a bearing 14. The bottom portion 15 of the pulley shaft 13 comes into contact with the fixed base (the engine body or the plate frame member attached to the engine body) 20 of the auto tensioner 10 via the friction material 16 formed of resin, and the hollow portion 17 of the pulley shaft 13 Is provided with a bolt 19 penetrating therethrough and screwed into a fixed base 20, a coil spring 21 and a friction material 23 which are elastic materials surrounding the bolt 19, and the urging force of the coil spring 21 causes the friction material 23 to move to the pulley shaft. bottom
15 so that the bottom 15 secures the friction material 16 to the base 20
It is crimped to the surface of. Arm 25 on pulley shaft 13
And the arm 26 are attached, the arm 25 engages with the coil spring 12 (FIGS. 5 and 6), and the arm 26 penetrates through the bolt 27 and the bolt 27 is screwed into the fixed base 20.

FIG. 5 shows a plan view of the auto tensioner 10. The pulley shaft 13 is bolted by the urging force of the spring 12.
It receives a moment M about the axis of 27. Further, the pulley shaft 13 has its bottom wall portion 15 engaged with the surface of the support member 20 through a friction material 16 by frictional contact, and the friction materials 16 and 23 have arcuate lengths centered around the bolt 27. Holes 32,33
Therefore, even if the pulley shaft 13 receives the moment M and moves within a certain range, the friction members 16 and 23 do not hit the bolt 19. Therefore, the tensioner pulley 11 can swing about the shaft of the bolt 27 within a predetermined range during the movement, and the frictional force between the friction material 16 and the support member 20 generated at this time damps the vibration. Is done.

As described above, in the technique disclosed in the above publication, the tensioner pulley 11 is made variable in position with respect to the belt 1 to keep the tension of the belt 1 at a predetermined value during operation, and the frictional force of the friction material 16 provides a damping effect. It prevents the increase of vibration.

[Problems to be solved by the device]

In the above-mentioned conventional example, the tension of the belt 1 is kept at a predetermined value by the urging force of the spring 12, and the vibration during operation is caused by the frictional force between the friction member 16 pressed by the spring 21 and the support member 20. Attenuates and absorbs. But,
According to this method, in a specific engine rotation range,
There is a problem in that the timing belt 1 and the tensioner 10 resonate and their respective vibrations increase, so that the rotational fluctuation of the cam shaft increases.

From the viewpoint of suppressing the resonance of the timing belt, it is better to increase the set value of the frictional force, but on the other hand, the frictional force needs to be set smaller than that of preventing the tensioner from sticking. Therefore, it is not appropriate to make a setting focusing on a specific rotation range from the viewpoint of the overall balance. Further, it is difficult to suppress the occurrence of resonance in a limited rotation range by the conventional method.

In view of the above problems, the present invention aims to prevent the strong resonance from occurring only in a specific rotation range by changing the frictional force according to the change of the rotation range. Is.

[Means for Solving the Problems]

In order to solve the above problems, in the present invention, an oscillating body is rotatably attached to a fixed base by a pivot, and an idle pulley is rotatably attached to the oscillating body via a pulley shaft. A long hole is formed in the center of the rocker along the rocking direction of the rocking body, and a rod that penetrates the long hole is erected on the fixed base. In a timing belt autotensioner configured to make frictional contact between the pulley shaft and a fixed base through a friction material, the rod is driven in the rod axial direction according to the engine speed to generate in the friction member. A friction type auto-tensioner resonance prevention device, characterized in that it is provided with means for changing the frictional force to be applied and restriction means for limiting the upper limit of the frictional force. Subjected to.

[Action]

The rod moves in the axial direction of the rod in accordance with the number of revolutions of the engine, the pressing force against the friction material changes, and therefore the friction force, that is, the damping force against vibration, becomes variable, and resonance of the autotensioner can be prevented. Further, since the upper limit of the frictional force can be limited, it is possible to prevent the autotensioner from sticking due to excessive frictional force in the high rotation range.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

The structure of the autotensioner according to the present invention has a lot in common with the above-mentioned prior art (FIGS. 4 to 6), so that the description will be made by comparing with these figures. Therefore, basically the same reference numerals are used in the drawings for the parts having the same configurations and functions,
Moreover, a part of the description is omitted.

The arrangement of the autotensioner 10 in the internal combustion engine is almost the same as that shown in FIG. 6 of the prior art, and the timing belt 1 with teeth, the timing pulley 2, the cam pulley 3, the oil pump pulley 4, the idler pulley 5, and the autotensioner are used. The positional relationship between the pulley 11 and the coil spring 12 is basically the same.

An explanatory view of a vertical cross section of the auto tensioner 10 according to this embodiment is shown in FIG. On the fixed base 20, the pulley shaft 13, the arm, and the pivot shaft 6 formed by the shaft 28 and the bush 31.
An oscillating body 7 formed by 25 and 26 is oscillatably attached. A tensioner pulley 11 is rotatably attached to the oscillating body 7 via a pulley shaft 13. The tensioner pulley 11 is rotatably attached to the center of the bottom portion 15 of the pulley shaft along the oscillating direction of the oscillating body 7 (a direction substantially perpendicular to the plane of FIG. The long hole 8 is formed, and the rod 18 penetrates the long hole.

Tensioner pulley 11, pulley shaft 13, bearing 14
The arrangement is the same as that shown in FIG.
The bottom 15 of the arm is joined at one outer end to the arm 25,
A spring 12 (see FIG. 5) is hooked on the tip of 25. Further, at the other outer end of the pulley shaft bottom portion 15, it is connected to an arm 26, and a shaft 28 is connected to the arm 26 via a bush 31.
Are fitted and the shaft 28 is screwed into the fixed base 20.

The pulley shaft 13 has a middle chamber 17 formed therein, which is hollow.
17 has rod 18, friction material 24 and pulley shaft bottom 15
The coil spring 22 is disposed between the head flange of the rod 18 and the friction material 24. A friction material 16 made of resin or the like is fixed to the bottom surface of the pulley shaft bottom portion 15 opposite to the hollow portion 17 side. rod
18 further extends and penetrates the fixed base 20, and a hollow chamber 30 constituted by a cylinder 36 and a piston 35 is provided at a position opposite to the hollow portion 17 with the fixed base 20 interposed therebetween. piston
35 is formed at the end of the rod 18, and the rod 18 is a sleeve.
It is slidably fitted to the fixed base 20 via 31. A spring 40 is provided in the cylinder 36 to urge the piston 35 in the direction of the head of the piston indicated by the arrow P. An oil hole 38 is opened on the side surface of the cylinder, from which oil is supplied as shown by an arrow. Further, a notch 41 and an oil discharge port 39 are provided inside the vicinity of the head of the cylinder.

The operation of the auto tensioner 10 having the above structure will be described below. 5, the autotensioner 10 receives a moment M by a spring 12, and the pulley 11 and the pulley shaft 13 rotate about a shaft 28 (corresponding to 27 in FIG. 5) forming the pivot shaft 6. . At this time, in FIG. 1, the parts that rotate together with the pulley 11 and the pulley shaft 13 are the arm 25 that forms the rocking body 7 and the bottom part of the pulley shaft.
15, friction material 16, arm 26, other parts, rod 18,
The friction material 24, the piston 35, the cylinder 36 and the like are stationary together with the fixed base 20 and do not rotate. At this time, the friction material 16 and the pulley shaft bottom portion 15 to which the friction material 16 is fixed have a structure shown in FIGS.
An elongated hole 8 as shown by 3 is provided, and this portion serves as a guide hole so that the rocking body 7 does not hit the rod 18 when rotating. Therefore, the rotatable portion, that is, the oscillating body 7 can always rotate integrally with each other to rotate about the shaft 28 as a central axis, and the tension of the belt 1 can be adjusted by moving the pulley 11 at this time. Be seen.

Also, as in the case shown in FIG.
The friction material 24 (23 in FIG. 4) is pressed by (21 in FIG. 4) and abuts against the pulley shaft bottom portion 15 to make frictional contact therewith.
Further presses the friction material 16 to abut the fixed base 20, and frictionally engages with the fixed base 20.

The configuration up to the above is almost the same as that of the conventional example, but in this embodiment, the feature is brought about by providing the hollow chamber 30 in addition to this. That is, the friction material is urged by the urging force of the spring 40 in the hollow chamber 30 and the hydraulic pressure.
The frictional force generated on 16, 24 was made strong, and the strength could be changed according to the condition. That is, through the oil hole 38 in the hollow chamber 30,
Introduce the oil pressure in the main oil passage of the engine. As a result, the pressing load of the spring 22 is further loaded by the hydraulic pressure in the spring 40 and the hydraulic chamber, and the frictional force generated in the friction material becomes stronger. In addition, the hydraulic pressure becomes higher when the engine speed becomes higher, so The higher the value, the stronger the frictional force. Further, by providing the notch 41 for draining the oil in the cylinder 36, the upper limit of the hydraulic pressure can be limited, and thus the upper limit of the frictional force can be limited. The oil that has flowed out of the notch 41 is returned to the oil pan through the opening 39.

2 and 3 show the frictional force generated in the friction material according to the prior art and the present invention (conventional example f, the present invention F), the frequency of the auto tensioner 10 (conventional example h, the present invention H) and the engine rotation. The relationship diagram with a number (N) is shown. As can be seen from FIG. 2, since the frictional force f is constant and low in the prior art, the frequency h sharply increases in a specific rotation range, and the tensioner resonates here. According to FIG. 3 showing the present invention, since the frictional force F increases as the rotation increases, resonance can be prevented, and the upper limit of the frictional force F can be limited by providing the notch 41 for removing the hydraulic pressure. Shows the characteristics of the one-dot chain lines H'and F'shown in the figure, and according to this, it is possible to prevent the autotensioner from sticking due to excessive frictional force in the high rotation range.

It should be noted that the hollow chamber 30 is not limited to oil, and intake negative pressure may be introduced, and a separate driving means such as a step motor may be additionally provided.

[Effect of device]

According to the present invention, by using the means for controlling the frictional force of the friction material of the auto tensioner by applying the driving force to the rod according to the engine speed, the frictional force is increased and the rotation of the engine is increased. The frictional force also increases in proportion to, which can prevent the resonance of the autotensioner. Further, since the upper limit of the frictional force can be limited, it is possible to prevent the autotensioner from sticking due to excessive frictional force in the high rotation range.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view of an autotensioner according to an embodiment of the present invention, and FIG. 2 is a frictional force-engine speed diagram of a conventional friction material and an autotensioner frequency-engine speed diagram. FIG. 3 is a friction force-engine speed diagram and a frequency-engine speed diagram according to the present invention, FIG. 4 is a longitudinal sectional view of an automatic tensioner of a conventional example, FIG. 5 is a plan view of FIG. FIG. 6 shows an assembly layout of the conventional automatic tensioner and the timing belt with teeth. 1 ... Timing belt, 6 ... Axis, 7 ... Oscillator,
8 ... Long hole, 10 ... Auto tensioner, 11 ... Tensioner pulley, 13 ... Pulley shaft, 15 ... Pulley shaft bottom, 16 ... Friction material, 18 ... Rod, 20 ... Fixed base, 22 ... … Elastic material,

Claims (1)

[Scope of utility model registration request] An oscillating body (7) is swingably attached to a fixed base (20) by a pivot (6), and a tensioner pulley (11) is attached to the oscillating body (7) via a pulley shaft (13).
Rotatably attached to the pulley shaft bottom (15)
A long hole (8) is bored along the swing direction of the rocking body (7) in the center of the rod (1) and a rod (1
8) Stand on the fixed base (20), and attach the rod (1
A timing belt configured such that the pulley shaft (13) and the fixed base (20) are brought into frictional contact with each other via the friction members (14, 24) by the urging force of the spring (22) fitted in 8). In the automatic tensioner (10) for driving, the means for driving the rod (18) in the axial direction of the rod according to the engine speed to change the frictional force generated in the friction material (14, 24), A friction type auto-tensioner resonance prevention device, characterized in that a regulation means for limiting the upper limit is provided.