JP2004138118A - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure strength of a spindle part 13 on a fixed member 14 while reducing size of packaging as the whole body of an auto tensioner. <P>SOLUTION: In the fixed member 14, a thick part 51 as a reinforcement part is provided on the opposite side of a direction in which the maximum bend stress of bending the spindle part 13 at a base end part during belt tension adjustment is applied to a spindle part center axis 13a. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to a technical field related to an auto-tensioner that automatically applies tension to a belt wound around a plurality of pulleys.
[0002]
[Prior art]
Conventionally, as this type of auto tensioner, a fixing member having a base and a spindle protruding from the surface of the base, a boss portion rotatably fitted to the spindle portion of the fixing member, and a boss A swinging member having an arm portion extending in a radial direction from the portion, a tension pulley rotatably supported by a tip end of the arm portion, and a belt wound around the swinging member, and a swinging member rotating the swinging member so that the tension pulley presses the belt. A torsion coil spring as a biasing means for dynamically biasing, and a spring support provided between the spring and the boss portion as a damping means for attenuating the swing of the swing member, automatically reducing the belt tension. Is known (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-7-151198
[Problems to be solved by the invention]
By the way, in the auto-tensioner as described in Patent Document 1, a bending stress acting on the spindle portion at the base end portion while adjusting the belt tension acts on the spindle portion. This bending stress concentrates on the base end of the spindle portion, which is the boundary between the base portion of the fixing member and the spindle portion on the surface thereof, and is particularly used in an auto-tensioner used in a belt transmission that requires a particularly high belt tension. Then, it becomes remarkable.
[0005]
Therefore, in order to maintain the strength of the base end portion of the spindle portion, it is necessary to increase the outer diameter of the spindle portion. However, when the outer diameter of the spindle portion is increased in this manner, the spindle portion is externally fitted to the spindle portion. The size of the swinging member and the like also increases, and accordingly, the entire packaging of the auto tensioner increases. For this reason, there is a problem that a large space is required for installing the auto tensioner.
[0006]
The present invention has been made in view of such a point, and an object of the present invention is to improve the structure of the fixing member to reduce the packaging of the entire auto tensioner while reducing the spindle portion of the fixing member. The purpose is to secure the strength of the base end.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a fixing member having a spindle portion protruding from a surface of a base portion and a boss portion which is swingably fitted to the spindle portion of the fixing member are provided. A swing member having: a tension pulley rotatably supported by the swing member and around which a belt is wound; an urging means for rotatingly urging the swing member so that the tension pulley presses the belt; It is assumed that an auto-tensioner includes damping means for damping the swing of the moving member and automatically adjusts the tension of the belt.
[0008]
In the fixing member, a reinforcing portion is provided in a direction in which a maximum bending stress for bending the spindle portion at the base end portion acts during adjustment of the belt tension, and on a side opposite to a center axis of the spindle portion.
[0009]
According to the above configuration, since the reinforcing portion is provided on the side opposite to the direction in which the maximum bending stress acts and the center axis of the spindle portion, the maximum bending stress acting on the base end portion of the spindle portion is dispersed by the reinforcing portion. Let me do. For this reason, the strength of the base end of the spindle portion can be increased without increasing the outer diameter itself of the spindle portion. Therefore, it is possible to secure the strength of the spindle portion while reducing the packaging of the entire auto tensioner.
[0010]
According to the second aspect of the present invention, the reinforcing portion is a thick portion formed by protruding the base surface of the fixing member more than other portions. According to this configuration, only the portion corresponding to the reinforcing portion on the base surface of the fixing member is swelled more than other portions, and that portion is made to be a thick portion, and the reinforcing portion is formed by this thick portion. Even without increasing the outer diameter of the spindle portion on which the maximum bending stress acts, the section modulus of the base end portion of the spindle portion is increased and the maximum value of the bending stress is reduced. Therefore, it is possible to secure the strength of the spindle portion while reducing the packaging of the entire auto tensioner.
[0011]
In the invention according to claim 3, the biasing means is a torsion coil spring disposed around the boss of the swinging member, and a spring support as a damping means is provided between the spring and the boss. The bending stress acting on the spindle portion of the fixing member is based on the combined force of the belt tension load received via the tension pulley by the belt tension and the spring pressing force of the spring support received from the spring.
[0012]
According to the above configuration, even when a bending stress acts on the base end portion of the spindle portion due to the resultant force of the belt tension load and the spring pressing force, necessary packaging can be performed without increasing the packaging of the auto tensioner. The strength of the spindle can be ensured.
[0013]
According to the fourth aspect of the present invention, the auto tensioner is used for a belt transmission for driving an accessory of an engine. According to this configuration, it is possible to obtain a suitable auto-tensioner that can remarkably exert the function and effect of the present invention.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 shows a belt transmission 1 according to an embodiment of the present invention. The belt transmission 1 is driven by an engine mounted on an automobile, for example, and its accessory is mounted on a crankshaft of an engine (not shown). It has a driving pulley 2 attached thereto, a tension pulley 31 provided on the auto tensioner 9, and first and second auxiliary pulleys 4 and 5 attached to a rotating shaft of an auxiliary machine (not shown). The drive pulley 2 and the first and second auxiliary pulleys 4 and 5 are both V-ribbed pulleys, while the tension pulley 31 is a flat pulley. The ribbed belt B is wound around the V-ribbed belt B by the rotation of the driving pulley 2 accompanying the operation of the engine. The V-ribbed belt B is driven by the driving pulley 2 → the tension pulley 31 → the first auxiliary pulley 4 → the second auxiliary pulley 5 → the driving pulley 2. Each accessory is driven in order to travel clockwise in FIG. 4 in order. The auto tensioner 9 applies a belt tension by pressing the loose side span B1 of the V-ribbed belt B.
[0015]
As shown in FIGS. 1 to 3, the auto tensioner 9 has a cup-shaped mounting portion 12 as a base having an outer wall 12 a on an outer peripheral portion, and a base end on a surface of the mounting portion 12 (a bottom surface in the mounting portion 12). And a fixing member 14 integrally formed with a tapered cylindrical spindle portion 13 protruding from the above. The fixing member 14 is made of, for example, a cast aluminum product. The mounting portion 12 has three mounting pieces 12b, 12b,... Protruding outward from the outer wall 12a in the radial direction and having bolt layer through holes 12c. A bolt (not shown) is inserted into a bolt insertion hole 12c of each mounting piece 12b and fastened to the engine main body while the back surface of the mounting portion 12 is in contact with a mounting surface of the engine main body (not shown). The fixing member 14 is non-rotatably mounted and fixed to the engine body.
[0016]
As shown in FIG. 3, a double cylindrical swinging member 20 is attached to the fixed member 14 via an insert bearing 16 as a damping means made of resin or the like having a predetermined friction coefficient. From the outside. The oscillating member 20 includes a cylindrical inner cylinder 21 externally fitted to the fixed member 14, a cylindrical outer cylinder 22 disposed concentrically outside the inner cylinder 21, and an inner and outer cylinder It has a boss portion 24 integrally formed with a disk portion 23 connecting the bases 21 and 22 on the base end side (front end side of the fixing member 14).
[0017]
The boss portion 24 is prevented from coming off at the disk portion 23 by a disk-shaped front plate 26 which is caulked and connected to the tip portion of the spindle portion 13 of the fixing member 14, and is connected to the disk portion 23 and the front plate 26. A disc-shaped thrust washer 27 as another damping means made of resin or the like having a predetermined coefficient of friction is interposed between the thrust washer 27 and the disk.
[0018]
An arm portion 30 extending radially from the outer periphery of the outer cylinder portion 22 of the boss portion 24 is integrally formed, and the tension pulley 31 is rotatable at the tip of the arm portion 30 via a bearing 32. It is supported by. The tension pulley 31 has a rotation axis parallel to the center axis 13a of the spindle portion 13 of the fixing member 14, and the back surface of the V-ribbed belt B (shown in FIG. 4) is wound around the outer peripheral surface thereof. .
[0019]
A torsion coil spring 35 is provided between the fixed member 14 and the swinging member 20 as urging means for urging the arm 30 to rotate. The spring 35 provides a tension pulley at the tip of the arm 30. 31 presses the V-ribbed belt B. Specifically, the spring 35 is interposed in a state where the spring 35 is located in the inner and outer cylindrical portions 21 and 22 of the boss portion 24, and one end of the spring 35 is notched in the mounting portion 12 of the fixing member 14. The other end is locked to the locking portion, and the other end is locked to a boss portion locking portion formed by cutting out the base end side of the outer cylindrical portion 22 of the boss portion 24 of the swinging member 20.
[0020]
Further, a substantially cylindrical spring support 40 is disposed between the outer surface of the inner cylindrical portion 21 of the swing member 20 and the spring 35 as a further damping means for damping the swing of the swing member 20. The spring support 40 is provided on a cylindrical portion 41 pressed against the outer peripheral surface of the inner cylindrical portion 21 by contraction of the diameter of the spring 35 caused by the swinging of the arm portion 30 in one direction, and is provided continuously with an end of the cylindrical portion 41. And an outward flange portion 42 whose rear surface is pressed against the surface of the mounting portion 12 of the fixing member 14 by the base end fixed end of the spring 35. In the present embodiment, the flange portion 42 of the spring support 40 and the base end side of the insert bearing 16 are integrally connected from the viewpoint of cost reduction, that is, both are integrally formed.
[0021]
When the automatic tensioner 9 is mounted on the belt transmission 1 and the belt driving device 1 is activated, the spindle unit 13 receives the belt received via the tension pulley 31 during the adjustment of the belt tension. Of the acting force Fb (shown in FIG. 4) due to the tension, the belt load Fh, which is a component that tends to bend the spindle portion 13 at the base end, and the tightening force that the cylindrical portion 41 of the spring support 40 receives from the spring 35 And the resultant force Fr (Fr = Fh + Fs) with the spring pressing force Fs acts.
[0022]
As a feature of the present invention, as shown in FIGS. 1 and 2, with respect to the direction in which the maximum bending stress for bending the spindle portion 13 at the base end by the resultant force Fr acts and the spindle portion central axis 13a. A reinforcing portion is provided on the opposite fixing member 14.
[0023]
Specifically, the maximum stress position 50 at which the maximum bending stress acts at the base end of the spindle portion 13 is specified based on the operating direction of the acting force Fb due to the belt tension applied to the arm portion 30 and the like. Then, the surface of the mounting portion 12 on the opposite side to the spindle portion center axis 13a at the maximum stress position 50 is bulged radially in a predetermined width w over a predetermined width w by a certain height h from other portions. , A thick portion 51 is formed, and the thick portion 51 constitutes a reinforcing portion.
[0024]
Next, the operation of the auto tensioner 9 according to the embodiment of the present invention will be described. The torsion spring force of the spring 35 urges the swinging member 20 (arm 30) to rotate in one direction (counterclockwise in FIG. 4) around the spindle 13 of the fixing member 14, and the distal end of the arm 30 is turned. The tension pulley 31 constantly presses the loose-side span B1 of the V-ribbed belt B, whereby tension is applied to the V-ribbed belt B. On the other hand, when the tension of the loose side span B1 of the V-ribbed belt B increases and the arm 30 of the swing member 20 swings around the fixed member 14 together with the tension pulley 31 against the spring force of the spring 35. The swing is damped by the insert bearing 16, the thrust washer 27 and the spring support 40. Thus, the tension of the V-ribbed belt B is automatically adjusted.
[0025]
At this time, the spindle load is applied to the spindle portion 13 from the belt load Fh, which is a component that tends to bend the spindle portion 13 at the base end portion, out of the acting force Fb due to the belt tension received via the tension pulley 31 and the spring 35. The resultant force Fr (Fr = Fh + Fs) with the spring pressing force Fs due to the tightening force received by the cylindrical portion 41 of the spring support 40 acts. The maximum stress at the base end of the spindle portion 13 at which the bending stress due to the resultant force Fr becomes maximum. Only the surface of the mounting portion 12 on the opposite side to the position 50 and the spindle portion central axis 13a is bulged more than the other portion, and that portion is made a thick portion 51, and the thick portion 51 constitutes a reinforcing portion. Therefore, even if the outer diameter of the spindle portion 13 on which the maximum bending stress acts is not increased, the section modulus of the base end portion of the spindle portion 13 can be increased. The maximum value of the bending stress is reduced me.
[0026]
Therefore, the strength of the spindle portion 13 can be secured while reducing the packaging of the entire auto tensioner 9.
[0027]
In the above embodiment, the maximum value of the bending stress applied to the base end portion of the spindle portion 13 can be suppressed by appropriately setting the height h and the width w of the thick portion 51.
[0028]
In the above-described embodiment, the thick portion 51 of the mounting portion 12 of the fixing member 14 bulges by a certain height h from the surface of the other mounting portion 12 as shown in FIG. However, as shown in FIG. 5, the thick part 51 is moved from the inner surface of the outer wall 12a of the mounting part 12 toward the central axis 13a of the spindle part 13 so that the height from the surface of the other mounting part 12 is h1. h2 may be gradually increased. Thus, it is possible to prevent the cross section modulus from suddenly decreasing and the stress from being concentrated on the cross section of the spindle portion 13 having no reinforcing portion.
[0029]
【The invention's effect】
As described above, in the auto-tensioner according to the first aspect of the present invention, the direction in which the maximum bending stress acting to bend the spindle portion at the base end during the adjustment of the belt tension and the central axis of the spindle portion are applied to the fixing member. On the opposite side, a reinforcing portion was provided. In the invention of claim 2, the thick portion formed by bulging the base surface of the fixing member more than other portions is used as the reinforcing portion. As a result, the strength of the spindle portion can be secured while reducing the packaging of the entire auto tensioner.
[0030]
According to the third aspect of the present invention, a combined force of the belt tension load received via the tension pulley by the belt tension and the spring pressing force by the tightening force received by the spring support from the torsion coil spring disposed around the boss portion of the swing member. Is defined as the bending stress acting on the spindle part. Further, in the invention of claim 4, the auto tensioner is used for a belt transmission for driving an auxiliary machine of an engine. As a result, a suitable auto-tensioner that can remarkably exert the effects of the present invention can be obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view taken along line II of FIG. 2;
FIG. 2 is a plan view showing a fixing member.
FIG. 3 is a sectional view showing an auto tensioner according to the embodiment of the present invention.
FIG. 4 is a front view showing the belt transmission.
FIG. 5 is a view corresponding to FIG. 1, showing another embodiment.
[Explanation of symbols]
1 Belt transmission 9 Auto tensioner 12 Mounting part (base)
13 Spindle 13a Center shaft 14 Fixing member 20 Swinging member 24 Boss 31 Tension pulley 35 Spring (biasing means)
40 Spring support (damping means)
51 Thick part (reinforcement part)
Fh Belt tension load Fs Spring pressing force Fr Resulting force B V-ribbed belt

Claims (4)

A fixed member having a spindle portion protruding from the surface of the base portion, a swing member having a boss portion which is swingably fitted to the spindle portion of the fixed member, and rotatably supported by the swing member. A tension pulley around which the belt is wound, biasing means for rotatingly rotating the swinging member so that the tension pulley presses the belt, and damping means for attenuating the swinging of the swinging member. In an auto-tensioner that automatically adjusts the tension,
The fixing member is provided with a reinforcing portion in a direction opposite to a direction in which a maximum bending stress acting to bend the spindle portion at a base end portion during adjustment of belt tension is opposite to a center axis of the spindle portion. An auto tensioner characterized by the following. In the auto tensioner according to claim 1,
An auto tensioner wherein the reinforcing portion is a thick portion formed by bulging a base surface of the fixing member more than other portions. In the auto tensioner according to claim 1 or 2,
The biasing means is a torsion coil spring disposed around the boss of the swing member,
A spring support as a damping means is provided between the spring and the boss portion,
The bending stress acting on the spindle portion of the fixing member is caused by a resultant force of a belt tension load received via a tension pulley by a belt tension and a spring pressing force by a tightening force received by a spring support from the spring. Features an auto tensioner. The auto tensioner according to any one of claims 1 to 3, wherein the auto tensioner is used for a belt transmission for driving an auxiliary device of an engine.

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