JP4191974B2 - Auto tensioner - Google Patents

Description

[0001]
BACKGROUND 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 an autotensioner of this type, a base member and a fixing member having a spindle portion protruding from the surface of the base portion, a boss portion that is rotatably fitted to the spindle portion of the fixing member, and the boss A swing member having an arm portion extending in a radial direction from the head portion, a tension pulley rotatably supported at the tip of the arm portion, and a swing pulley around which the belt is wound so that the tension pulley presses the belt. A torsion coil spring as a biasing means for dynamic biasing, and a spring support as a damping means provided between the spring and the boss portion for damping the swinging of the swinging member, automatically tension the belt. What is adjusted to be known is known (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-7-151198 [0004]
[Problems to be solved by the invention]
By the way, in the auto tensioner like the above-mentioned patent document 1, a bending stress is applied to the spindle portion so as to bend the spindle portion at the base end during adjustment of the belt tension. This bending stress is concentrated at the base end of the spindle part, which is the boundary between the base part of the fixing member and the spindle part on the surface thereof, and is used for a belt transmission device 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. When the outer diameter of the spindle portion is increased in this way, the spindle portion is fitted outside. The size of the swing member and the like is also increased, and accordingly, the entire packaging of the auto tensioner is increased. For this reason, there is a problem that a large space is required to install the auto tensioner.
[0006]
The present invention has been made in view of such points, and the object of the present invention is to devise the structure of the fixing member to reduce the packaging of the entire auto tensioner and to reduce the spindle portion of the fixing member. The purpose is to ensure 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, there is provided a fixing member having a spindle projecting from the surface of the base, and an inner cylinder part that is swingably fitted to the spindle part of the fixing member . The outer cylinder part concentrically arranged on the outer side of the inner cylinder part, the boss part having a disk part for connecting the inner and outer cylinder parts to each other on the distal end side of the fixing member , and the outer cylinder part of the boss part extend in the radial direction. A swinging member having an arm portion provided, a tension pulley rotatably supported by the swinging member, and a biasing member for rotating and biasing the swinging member so that the tension pulley presses the belt. It is premised on an auto tensioner which is provided with a biasing means and a damping means for damping the swinging of the swinging member so as to automatically adjust the belt tension.
[0008]
The biasing means is a torsion coil spring disposed between the inner and outer cylinder portions of the swing member, and a spring support as a damping means is provided between the spring and the inner cylinder portion, and the spring support Is a cylinder portion that is pressed against the outer peripheral surface of the inner cylinder portion by contraction of the diameter of the spring accompanying the swing of the arm portion in one direction, and a base end of the spring that is connected to an end portion of the cylinder portion. A laterally fixed end and an outward flange portion whose back surface is pressed against the base surface of the fixing member, and the fixing member has a maximum to bend the spindle portion at the base end portion during belt tension adjustment. a position opposite to the spring is not pressed to the direction and the spindle unit center axis bending stress acts, the thick portion is provided comprising swelled than other portions of the base surface of the fixing member Is, bending stress acting on the spindle part of the fixing member is intended a belt tension load by the belt tension received via the tension pulley, by the resultant force of the spring pressing force by the tightening force of the spring support receives from the spring There is .
[0009]
That is, the bending stress acts on the base end of the spindle part due to the resultant force of the belt tension load and the spring pressing force, but the position where the maximum bending stress acts and the spring on the opposite side of the spindle center axis are not in pressure contact Since the thick portion is provided on the surface of the base portion of the fixing member, the section modulus of the base end portion of the spindle portion is increased, and the maximum value of the bending stress is reduced. Since the thick wall portion is formed by bulging only the base surface of the fixing member that needs to be reinforced than the other portions, the strength of the base end portion of the spindle portion is increased without increasing the outer diameter of the spindle portion itself. Can be raised. Therefore, Ru can ensure the strength of the spindle unit while reducing the packaging of the entire auto tensioner.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 shows a belt transmission device 1 according to an embodiment of the present invention. The belt transmission device 1 drives an auxiliary machine by an engine mounted on, for example, an automobile. It has a drive pulley 2 attached, a tension pulley 31 provided in the auto tensioner 9, and first and second auxiliary pulleys 4 and 5 attached to a rotating shaft of an auxiliary device (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, and V between these pulleys 2, 4, 5 and 31. 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 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 in the clockwise direction in FIG. The auto tensioner 9 presses the slack side span B1 of the V-ribbed belt B to apply belt tension.
[0011]
As shown in FIGS. 1 to 3, the auto tensioner 9 has a cup-shaped mounting portion 12 as a base portion having an outer wall 12 a on the outer peripheral portion, and a base end on the surface of the mounting portion 12 (the bottom surface in the mounting portion 12). A fixed member 14 is integrally formed with a tapered tapered cylindrical spindle portion 13 projecting from the above. The fixing member 14 is made of, for example, an aluminum casting, and the mounting portion 12 includes three mounting pieces 12b, 12b,... That protrude radially outward from the outer wall 12a and have bolt layer through holes 12c. By fastening to the engine body through a bolt (not shown) through the bolt insertion hole 12c of each mounting piece 12b with the back surface of the mounting portion 12 in contact with the mounting surface of the engine body (not shown). The fixing member 14 is non-rotatably attached and fixed to the engine body.
[0012]
As shown in FIG. 3, the fixed member 14 has a double cylindrical rocking member 20 on the front end side of the spindle portion 13 through an insert bearing 16 as a damping means made of resin having a predetermined friction coefficient. And is fitted outside so as to be swingable. The swinging member 20 includes a cylindrical inner cylinder portion 21 that is externally fitted to the fixing member 14, a cylindrical outer cylinder portion 22 that is disposed concentrically outside the inner cylinder portion 21, and an inner and outer cylinder portion. It has the boss | hub part 24 which integrally formed the disk part 23 which connects 21 and 22 by the base end side (fixing member 14 front end side).
[0013]
The boss portion 24 is secured to the disc portion 23 by a disc-shaped front plate 26 that is caulked and joined to the tip portion of the spindle portion 13 of the fixing member 14, and the disc portion 23 and the front plate 26 are joined. A disc-shaped thrust washer 27 as another damping means made of resin or the like having a predetermined friction coefficient is interposed between them.
[0014]
The outer cylindrical portion 22 of the boss portion 24 is integrally formed with an arm portion 30 extending in the radial direction from the outer periphery, and the tension pulley 31 is freely rotatable via a bearing 32 at the distal end portion of the arm portion 30. It is supported by. The tension pulley 31 has a rotation axis parallel to the central 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. .
[0015]
A torsion coil spring 35 is provided between the fixed member 14 and the swinging member 20 as a biasing means for pivotally biasing the arm portion 30, and the tension pulley at the tip of the arm portion 30 is provided by the spring 35. 31 presses the V-ribbed belt B. Specifically, the spring 35 is interposed in the state where the spring 35 is located in the inner and outer cylindrical portions 21 and 22 of the boss portion 24, and although not shown, one end of the spring 35 is notched in the mounting portion 12 of the fixing member 14. The other end is engaged with the engaging portion, and the other end is engaged with a boss portion-side engaging portion formed by cutting out the base end side of the outer tube portion 22 of the boss portion 24 of the swing member 20.
[0016]
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 connected to a cylindrical portion 41 that is pressed against the outer peripheral surface of the inner cylindrical portion 21 by contraction of the diameter of the spring 35 accompanying the swinging of the arm portion 30 in one direction, and an end portion of the cylindrical portion 41. The rear surface of the fixing member 14 is pressed against the surface of the mounting portion 12 by the base end side 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.
[0017]
When such an auto tensioner 9 is mounted on the belt transmission device 1 and the belt driving device 1 is in an operating state, the spindle portion 13 receives a belt received via a tension pulley 31 during belt tension adjustment. Of the acting force Fb (shown in FIG. 4) due to tension, the belt load Fh, which is a component for bending the spindle portion 13 at the base end portion, and the tightening force received by the cylindrical portion 41 of the spring support 40 from the spring 35. The resultant force Fr (Fr = Fh + Fs) with the spring pressing force Fs is applied.
[0018]
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 portion by the resultant force Fr acts and the spindle portion central axis 13a, The fixing member 14 on the opposite side is provided with a reinforcing portion.
[0019]
Specifically, the maximum stress position 50 at which the maximum bending stress acts at the base end portion of the spindle portion 13 is specified from the acting direction or the like of the acting force Fb due to the belt tension received by the arm portion 30. Then, the surface of the mounting portion 12 on the opposite side of the spindle portion central axis 13a at the maximum stress position 50 is bulged by a certain height h over the predetermined width w along the radial direction from the other portions. A thick part 51 is formed, and the thick part 51 constitutes a reinforcing part.
[0020]
Next, the operation of the auto tensioner 9 according to the embodiment of the present invention will be described. Due to the torsion spring force of the spring 35, the swing member 20 (arm portion 30) is urged to rotate in one direction around the spindle portion 13 of the fixing member 14 (counterclockwise in FIG. 4). The tension pulley 31 always presses the slack side span B1 of the V-ribbed belt B, and thereby tension is applied to the V-ribbed belt B. On the other hand, when the tension of the slack side span B1 of the V-ribbed belt B increases and the arm portion 30 of the swing member 20 swings around the fixing member 14 against the spring force of the spring 35 together with the tension pulley 31. The oscillation is damped and braked by the insert bearing 16, the thrust washer 27, and the spring support 40. As a result, the tension of the V-ribbed belt B is automatically adjusted.
[0021]
At this time, the spindle portion 13 includes a belt load Fh, which is a component that tends to bend the spindle portion 13 at the base end portion, among 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 clamping force received by the cylindrical portion 41 of the spring support 40 acts, but the maximum stress at the base end portion of the spindle portion 13 where the bending stress due to this resultant force Fr is maximized. Only the surface of the mounting portion 12 opposite to the position 50 and the spindle portion central axis 13a is bulged more than the other portion, and that portion becomes a thick portion 51, and the thick portion 51 constitutes a reinforcing portion. Therefore, the section modulus of the base end portion of the spindle portion 13 is large without increasing the outer diameter itself of the spindle portion 13 on which the maximum bending stress acts. The maximum value of the bending stress is reduced me.
[0022]
Therefore, the strength of the spindle portion 13 can be ensured while reducing the packaging of the entire auto tensioner 9.
[0023]
In the above embodiment, the maximum value of the bending stress applied to the proximal 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.
[0024]
Moreover, in the said embodiment, as shown in FIG. 1, the thick part 51 in the attaching part 12 of the fixing member 14 bulges only by the fixed height h rather than the surface of the other attaching part 12, and an upper surface is horizontal. However, as shown in FIG. 5, the height of the thick part 51 from the inner surface of the outer wall 12a of the mounting part 12 toward the central axis 13a of the spindle part 13 from the surface of the other mounting part 12 is h1. You may make it become large gradually in h2. As a result, it is possible to prevent stress from being concentrated due to a sudden decrease in the section modulus in the cross section of the spindle portion 13 having no reinforcing portion.
[0025]
【The invention's effect】
As described above, in the auto tensioner of the present invention, the belt tension load received through the tension pulley by the belt tension during the adjustment of the belt tension, and the torsion coil spring arranged around the boss portion of the swing member The base of the fixing member is located at the position where the bending stress acting on the spindle part, which is the combined force of the spring pressing force due to the tightening force received by the support, is the largest acting direction and the opposite side of the spindle center axis and the spring does not press. A thick part formed by bulging the surface more than other parts was provided. Therefore, the maximum value of the bending stress in the section modulus of the spindle portion proximal end is increased is reduced, Ru can ensure the strength of the spindle unit while reducing the packaging of the entire auto tensioner.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view taken along a line II in FIG.
FIG. 2 is a plan view showing a fixing member.
FIG. 3 is a cross-sectional view showing an auto tensioner according to an embodiment of the present invention.
FIG. 4 is a front view showing a belt transmission device.
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 part 13a Center shaft 14 Fixing member 20 Oscillating member 24 Boss part 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 resultant force B V-ribbed belt

Claims (1)

A fixing member having a spindle protruding from the surface of the base,
An inner cylinder part that is swingably fitted to the spindle part of the fixing member, an outer cylinder part that is arranged concentrically outside the inner cylinder part, and the inner and outer cylinder parts are connected to each other at the distal end side of the fixing member. A swing member having a boss portion having a disc portion and an arm portion extending in a radial direction on an outer cylindrical portion of the boss portion ;
A tension pulley that is rotatably supported by the swing member and around which a belt is wound;
A biasing means for biasing the swinging member so that the tension pulley presses the belt;
Attenuating means for attenuating the swinging of the swinging member,
In an auto tensioner that automatically adjusts the belt tension,
The biasing means is a torsion coil spring disposed between the inner and outer cylinders of the swing member,
A spring support as the damping means is provided between the spring and the inner cylinder portion,
The above spring support
A cylindrical portion that is pressed against the outer peripheral surface of the inner cylindrical portion by contraction of the diameter of the spring accompanying the swinging of the arm portion in one direction;
An outward flange portion that is connected to the end portion of the cylindrical portion, and whose back surface is pressed against the base portion surface of the fixing member by the base end side fixed end of the spring;
The aforementioned fixing member, in a position opposite to the spring is not pressed to the direction and the spindle portion central axis maximum bending stress acts to bend the spindle unit during adjustment of the belt tension at the proximal end, the thick portion is provided et been made also swelled from other portions of the base surface of the fixing member,
The bending stress acting on the spindle part of the fixing member is
Belt tension load received through the tension pulley by belt tension;
An auto tensioner characterized by a resultant force combined with a spring pressing force by a clamping force received by a spring support from the spring .

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