JP2001165252A - Belt tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt tensioner with simple structure that requires no strict working precision. SOLUTION: A damper unit 4 consisting of a hollow cylindrical shaft (inside member) 3 and a boss part 5a with an oil chamber (cavity part) 23 around the hollow cylindrical shaft 3 being supported possible to turn freely, is provided at one end part of a belt tension. At the other end part, a tension pulley 7 is connected to a belt 11. The damper unit 4 forms the oil chamber 23 around the whole circumference between the hollow cylindrical shaft 3 and the boss part 5a. Oil with high viscosity is enclosed in the oil chamber 23, and the shearing resistance of oil attenuates relative turning of the hollow cylindrical shaft 3 and the boss part 5a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tensioner for a belt drive mechanism used for driving accessories of an engine.

[0002]

2. Description of the Related Art As a conventional belt tensioner, for example, one shown in FIGS. 4 and 5 is disclosed in Japanese Utility Model Laid-Open Publication No. 1-131058.

FIG. 4 is an overall view of the belt tensioner 201, and FIG. 5 is a sectional view of the damper 203 in a direction perpendicular to the axis.

[0004] A case 205 (see FIG.
) Of the holder 207 (see FIG. 4).
It is press-fitted into the inner periphery of a and is integrated. The holder 207 itself is attached and fixed to the engine by its flange portion 207b. A crescent-shaped sleeve 209 facing the inner periphery of the case 205 is press-fitted. Thus, the holder 207, the case 205, and the sleeve 209 are integrated, and are fixed to the engine.
Two lightening portions 211 extending in the axial direction are provided at two places on the middle between the opposing sleeves 209. And
A rotor 213 is rotatably inserted inside the sleeve 209.

Further, grooves 215 and 215 extending in the axial direction and having a substantially semicircular cross section are provided on the outer periphery of the rotor 213, and the rollers 217 are rotatably fitted in the grooves. The outer half of the roller 217 is
11 is arranged so as to be divided into two in the circumferential direction. Grease, silicone oil, or the like is sealed in the lightening portions 211 divided into two on both sides of the roller 217 shown in FIG. 5, that is, in each hollow portion.

On the other hand, the small-diameter shaft portion 213a of the rotor 213
(See FIG. 4), a bracket 2 having one side end integrated therewith.
21 is an idler pulley 22 of a belt drive mechanism
3 is attached. Thus, the bracket 22
1, i.e., the idler pulley 223 is urged by the torsion coil spring 225 to rotate with the rotor 213.
13 is rotated in a predetermined rotation direction about the axis of the shaft 13 to apply tension to the belt of the belt transmission mechanism.

When the idler pulley 223 (that is, the rotor 213) is rotated by the belt during power transmission, grease or silicon oil in the hollow portion (lightening portion 211) on one side of the roller 217 of the auto tensioner 201 is used. Is compressed by the roller 217 and the rotor 2
13 resists rotation. At this time, case 205
A small amount of grease or silicone oil leaks into the cavity on the opposite side from the gap between the roller and the roller 217, and attenuates the vibration of the belt transmission mechanism.

[0008]

However, in the above-mentioned conventional structure, since the compression pressure is generated in the hollow portion, it is necessary to increase the degree of sealing of the hollow portion. Strict machining accuracy is required for these parts so as to reduce the clearance of the fitting portion and the clearance between the case 205 and the roller 217.
There is a problem that the cost is high.

Accordingly, an object of the present invention is to provide a belt tensioner which has a simple structure and does not require strict processing accuracy.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 has an inner member at one end and a hollow portion around the inner member, and is rotatably supported. A belt tensioner provided with a tension pulley in contact with the belt at the other end, wherein the damper unit has the hollow portion entirely between the inner member and the outer member. The viscous fluid is sealed in the cavity, and the relative rotation of the inner member and the outer member is attenuated by the shear resistance of the viscous fluid.

Therefore, the sealing of the cavity for enclosing the viscous fluid can be easily performed by the seal member, and a belt tensioner can be obtained with a simple configuration without requiring strict processing accuracy.

Also, unlike the above-described conventional example in which the pressure rise resistance caused by compressing the cavity is utilized, the structure utilizing the shear resistance of the viscous fluid in the cavity is advantageous in terms of the durability of the seal member. .

According to a second aspect of the present invention, there is provided the belt tensioner according to the first aspect, wherein the damper unit comprises:
An urging member for urging the relative position between the inner member and the outer member to the initial position is provided across the inner member and the outer member, and the urging member and the cavity are substantially aligned in the rotation axis direction. It is characterized by being arranged at the same position.

Therefore, the same operation and effect as those of the first aspect of the invention can be obtained, and even if an urging member for urging the inner member and the outer member to the initial position is provided, the rotation of the damper unit can be achieved. It is possible to reduce the length in the direction of the moving shaft, so that space saving is improved and the degree of freedom of design is improved.

[0015]

1 to 3 show an embodiment of the present invention.
This will be described below. FIG. 1 is a sectional view of the present embodiment. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 shows a drive system of an engine accessory to which the belt tensioner of the present embodiment is applied.

As shown in FIG. 1, the belt tensioner 1
Is a damper unit 4 composed of a hollow cylindrical shaft (inner member) 3 at one end and a boss (outer member) 5a, which is one end of a bracket 5 described later, and a tension pulley 7 at the other end. And a bracket 5 provided with:

As shown in FIG. 3, one belt 11 is wound around each accessory of the engine, and an air conditioner pulley 15, a water pump pulley 17,
An alternator pulley 19 and a power steering pump pulley (hereinafter abbreviated as a power steering pump pulley) 21 are driven. The belt tensioner 1 is disposed between the power steering pump pulley 21 and the crank pulley 13 and applies tension to the belt 11 in the direction of arrow B.

The damper unit 4 is specifically configured as follows.

The hollow cylindrical shaft 3, which is the main component of the structure, has an outer cylindrical portion 3a and an inner cylindrical portion 3b, which are arranged double with an end wall portion 3c interposed therebetween, and are integrally formed. A mounting flange 3d is formed at the end of the inner cylindrical portion 3b opposite to the end wall 3c.

A hollow boss 5a of a bracket 5 described later is externally inserted into the outer cylindrical portion 3a. This hollow boss 5a
A ring-shaped oil chamber (cavity) 2 having a predetermined width over the entire circumference between the inner circumference of the hollow cylinder 3 and the outer circumference of the outer cylindrical portion 3a of the hollow cylindrical shaft 3.
3 are provided. High-viscosity oil such as silicone oil is injected into the oil chamber 23 from an oil injection port 25 provided in the boss 5 a of the bracket 5.
Further, X rings 27 are arranged at both ends of the oil chamber 23 to seal the oil chamber 23.

Reference numeral 31 denotes a torsion spring (urging member) for urging the relative position between the inner cylindrical shaft 3 and the boss 5a of the bracket 5 to the initial position, and is provided between the inner cylindrical shaft 3 and the boss 5a. It is.

More specifically, the torsion spring 31 includes an outer cylindrical portion 3a and an inner cylindrical portion 3b of the hollow cylindrical shaft 3.
As shown in FIG. 1, one end 31a is inserted into the hole of the boss 5a of the bracket 5 and fixed, while the other end 31b is connected to the end of the hollow cylindrical shaft 3 as shown in FIG. Wall 3
It is inserted into hole c and fixed by caulking.

In this state, the damper unit 4
The mounting flange 3d abuts against the wall of the engine and is fixed by the bolt 35. At this time, the hollow cylindrical shaft 3 and the boss 5a of the bracket 5 are fixed together with the dust cover 33 by bolts 35, and the hollow cylindrical shaft 3 is prevented from rotating by a rotation preventing pin 37 provided on the mounting flange 3d. .

An arm 5b extends from the boss 5a of the bracket 5, and a shaft 41 is fixed to the tip of the arm 5b, which is the other side of the bracket 5, and the tension pulley 7 is connected to the shaft 41. It is rotatably supported by and is secured.

Next, the attachment and operation of the belt tensioner 1 will be described.

In mounting the belt tensioner 1, when the drive belt 11 is extended by a predetermined length with respect to the initial length of the belt, the torsion spring 31 provides a torsional restoring force to allow the drive belt 11 to provide extra tension in the direction of applying tension to the drive belt 11. So that the dynamic stroke remains on the tension pulley 7
The torsion spring 31 is attached in a state where a torsional deformation is given in advance.

During operation, the torsional load on the bracket 5 fluctuates with the rotation of the crankshaft of the engine, and the inner circumference of the boss 5a of the bracket 5 and the outer cylindrical part 3a of the cylindrical shaft 3
Relative rotation occurs. At this time, a shearing action is generated in the oil in the oil chamber 23, and a resistance is generated by the viscosity of the oil, and a damping force is generated to perform a damping action.

The configuration for generating the resistance to the shearing action of the oil is not limited to the above-described ring-shaped oil chamber 23, but may be a viscous resistance such as a disk shape, a cylindrical overlap type, or a radial blade type. A configuration using any known member may be used.

Thus, according to the present embodiment, the oil chamber 23 can be easily sealed by the X-ring 27, so that the belt tensioner 1 having a simple configuration can be obtained without requiring strict processing accuracy.

Further, unlike the above-described conventional example in which the pressure rising resistance is achieved by compressing the hollow portion, the structure in which the shear resistance of the oil in the oil chamber 23 is used is advantageous in terms of the durability of the X ring 27. It is.

Also, unlike the above-mentioned conventional example, by adopting the structure of this embodiment, the length of the damper unit 4 in the rotation axis direction can be shortened, so that the space saving is improved. The degree of freedom of design is improved.

[0032]

As is apparent from the above description, according to the first aspect of the present invention, the sealing of the hollow portion between the inner and outer members can be easily performed by the seal member, so that strict processing accuracy is required. Thus, a belt tensioner having a simple configuration can be obtained.

Further, unlike the above-described conventional example in which the boost pressure caused by compressing the cavity is utilized, the structure utilizes the shear resistance of the viscous fluid in the cavity, which is advantageous in terms of the durability of the seal member. .

According to the invention described in claim 2, according to claim 1
The same effect as that of the invention can be obtained, and the length of the damper unit in the rotation axis direction can be shortened, so that space saving and design flexibility are improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram showing a drive system of an engine accessory to which the belt tensioner of one embodiment is applied.

FIG. 4 is an overall view of a conventional example.

FIG. 5 is a sectional view of a main part of a conventional example.

[Explanation of symbols]

 Reference Signs List 3 cylindrical shaft (inner member) 3a outer cylindrical portion 3b inner cylindrical portion 3c end wall portion 3d flange 4 damper unit 5 bracket 5a boss portion (outer member) 5b arm portion 7 tension pulley 23 oil chamber (hollow portion) 25 inlet 27 X ring 31 Torsion spring 33 Dust cover 41 Shaft

Claims (2)

[Claims] 1. A damper unit comprising an inner member at one end and an outer member rotatably supported with a cavity around the inner member, and a tension contacting the belt at the other end. A belt tensioner provided with a pulley, wherein the damper unit is configured such that the hollow portion is formed over an entire circumference between an inner member and an outer member, and a viscous fluid is sealed in the hollow portion. A belt tensioner that attenuates relative rotation between the inner member and the outer member due to shear resistance of the belt tensioner. 2. The belt tensioner according to claim 1, wherein the damper unit includes an urging member for urging a relative position between the inner member and the outer member to an initial position, between the inner member and the outer member. And a biasing member and the hollow portion are disposed at substantially the same position in a rotation axis direction.