JP2981433B2 - Auto tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A conventional automatic tensioner is a transmission device that transmits driving force to a plurality of devices by a single belt.
It is used to prevent the belt from bending and transmit the driving force reliably. Such an automatic tensioner is configured such that a tensioner arm is swingably mounted on a tensioner cup fixed to a predetermined portion such as an engine block, and a pulley is rotatably provided on the tensioner arm. A torsion spring is mounted between the tensioner cup and the tensioner arm to bias the tensioner arm in the direction in which the belt is tensioned.

A damping band as a friction member (damping member) is provided between the tensioner cup and the tensioner arm. A pin is formed on the tensioner arm, and an engaging portion having a hole that fits into the pin is formed on the damping band so as to protrude toward the inner peripheral surface. The pin and the hole are fitted, and the damping band and the tensioner arm rotate integrally. The outer peripheral surface of the damping band is in sliding contact with the inner peripheral surface of the tensioner cup, and the damping band is provided with a ring spring that urges the tensioner cup from inside. When the tensioner arm is rotated, a damping force is generated between the damping band and the tensioner cup, and imparts swing resistance to the tensioner arm.

[0004]

There are mainly three loads acting on the damping band. That is, the rotational force is applied to the engaging portion that is fitted to the tensioner arm, the rotational force is generated by the bias of the torsion spring, which is opposite to the rotational force, and the ring spring presses radially outward.

However, in the above-described conventional auto tensioner, stress tends to concentrate on the engaging portion of the damping band, particularly on the corner of the surface where the damping band and the ring spring are engaged. There has been a problem that the damping band may be damaged during use.

In view of the foregoing, an object of the present invention is to provide an auto-tensioner having a damping band which does not easily cause crack breakage and has excellent durability.

[0007]

An automatic tensioner according to the present invention includes a tensioner cup, a tensioner arm swingably attached to an opening of the tensioner cup, and a sliding contact with an inner peripheral surface of the opening of the tensioner cup. A damping member including a possible annular portion and an arm engaging portion formed to protrude inward from a part of the inner peripheral surface of the annular portion and having a mounting hole to be fitted to a pin formed on the tensioner arm; A ring spring provided on a support surface of the arm engaging portion opposite to the tensioner arm, and for urging the damping member toward the inner peripheral surface of the tensioner cup, between the support surface of the damping member and the annular portion. A round portion having a predetermined diameter is formed at the corner formed at the corner, and a ring spring engaging surface having a height corresponding to the diameter of the round portion is formed. There.

In the auto tensioner, a ring spring engagement surface may be formed by a support protrusion provided on a support surface of the damping member.

Further, in the auto tensioner, a plurality of support protrusions may be provided on one arm engaging portion, or the support protrusion may have a disk shape.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an auto tensioner according to the present invention will be described below with reference to the accompanying drawings.

The auto-tensioner according to the present embodiment is used, for example, in an automobile engine belt system as shown in FIG. The belt system includes a driving pulley 11 attached to an output shaft of an engine, driven pulleys 12, 13, and 14 for an air conditioner, a power steering device, and an alternator, and pulleys 15 and 1 for an idler.
6, and a belt tensioner 10, with a single drive belt 17 suspended between each pulley.

The belt tensioner 10 includes a fixed portion 20 fixed to the engine block, and a tensioner pulley 40 rotatably provided on the fixed portion 20 about a pivot bolt 23 serving as a swing shaft. ing. The tensioner pulley 40 is urged upward in the figure by a torsion spring 50 (see FIG. 2) provided in the fixed portion 20, and tensions the drive belt 17 by this urging force.
When the drive belt 17 is mounted, the tensioner pulley 40 is mounted while being rotated to the position shown by the broken line in the figure.

FIG. 2 is a sectional view showing the structure of the automatic tensioner of the present embodiment, and FIG. 3 is an exploded view showing parts of the automatic tensioner. First, a schematic configuration of the auto tensioner will be described. The fixing part 20 is fixed to the engine block by bolts. A torsion spring 50 is provided in the tensioner cup 22 of the fixed part 20. A pivot bolt 23 is fixed to the center of the tensioner cup 22. By inserting the pivot bolt 23, the tensioner arm 30 is swingably attached to the opening of the tensioner cup 22. A pulley bolt 41 parallel to the pivot bolt 23 is fitted into the tensioner arm 30. The tensioner pulley 40 includes a pulley bolt 41.
Is provided on the tensioner arm 30 so as to be rotatable. A substantially annular damping band 32 serving as a friction member is attached to the tensioner arm 30, and the outer peripheral surface of the damping band 32 is in sliding contact with the inner peripheral surface of the tensioner cup 22.

Next, each member of the auto tensioner will be described in detail. The fixing part 20 includes a mounting hole 21 and a tensioner cup 22. Two mounting holes 21 are provided on the outer periphery of the tensioner cup 22, and bolts (not shown) for fixing to the engine block are inserted. At the center of the bottom surface of the tensioner cup 22, a bolt engaging portion 22a that stands up into the cup is formed. The pivot bolt 23 is fixed to the tensioner cup 22 by screwing a screw portion 23a formed at the lower end of the pivot bolt 23 to the bolt engaging portion 22a.

The pivot bolt 23 is connected to the screw 2 from the lower end.
3a, hexagonal portion 23b, cylindrical portion 23c, screw portion 23d
It is composed of The lower end of the hexagonal portion 23b is connected to the bolt engaging portion 2 of the tensioner cup 22.
It is tightened to a position where it contacts the upper end of 2a. The cylindrical portion 23c is inserted into the pivot bushing 31 fitted into the cylindrical hole 30h of the tensioner arm 30. A nut 24 is screwed onto the screw portion 23d, and regulates the axial movement of the pivot bushing 31.

The tensioner arm 30 is formed of a metal material, and has a substantially disk-shaped lid 30b and a pulley mounting portion 3b.
0c. The pulley mounting portion 30c
A pulley bolt bearing 3 for screwing a pulley bolt 41 at the center is formed in a substantially disk shape eccentric to the lid 30b.
0 g is provided.

A cylindrical hole 30h is provided substantially at the center of the lid 30b so as to protrude upward, and a pivot bushing 31 is fitted from above. The pivot bushing 31 has the lid 3
With respect to 0b, it can swing with a predetermined frictional resistance in the rotational direction. Since the lid 30 b is swingably attached to the opening of the tensioner cup 22, the tensioner arm 30 rotates around the pivot bolt 23, which is a swing axis, with respect to the fixed part 20.

At the end of the lid 30b on the side of the pulley mounting portion 30c, two pins 30a, which are cylindrical projections, are formed.
These pins 30a extend from the lower surface of the lid 30b along the axial direction of the tensioner cup 22. The lid 30
On the lower surface of b, a locking portion 30d is provided in the vicinity of the cylindrical hole 30h so as to protrude toward the tensioner cup 22, and the end portion 52 of the torsion spring 50 is engaged.

The torsion spring 50 is formed by spirally winding a metal wire, and has one end 51 connected to the tensioner cup 2.
The other end 52 is fixed to the tensioner arm 30 on the bottom surface of the second member 2. The torsion spring 50 is interposed in a compressed state between the tensioner cup 22 and the tensioner arm 30 in an appropriately twisted state, and in this state, tensions a drive belt (not shown) suspended on the tensioner pulley 40. Then, the tensioner arm 30 is urged in the rotation direction.

The tensioner pulley 40 is rotatably mounted on a pulley mounting portion 30c of the tensioner arm 30 by a pulley bolt 41 via a ball bearing 42. Between the head of the pulley bolt 41 and the ball bearing 42, a dust shield 43 for preventing intrusion of dust is interposed.

The damping band 32 will be described with reference to FIGS. FIG. 4 is a view of the damping band 32 as viewed from the tensioner arm 30 side (above FIG. 3). FIG. 5 is a perspective view of a cross section taken along line II of FIG. 4 as viewed from the direction of the arrow, and FIG. 6 is a cross sectional view thereof. FIGS. 7 and 8 are a perspective view and a sectional view showing a state where the ring spring 33 is mounted on the damping band 32. 5 to 8, the surface of the damping band 32 facing the tensioner cup 22 is set to the upper side.

A damping band 32 as a friction member
Is attached to the tensioner arm 30. The damping band 32 is formed of an elastic member such as resin or rubber. For example, polyacetal, a polymer material such as nylon containing molybdenum for imparting self-lubricating properties, glass fiber reinforced nylon having excellent strength, carbon fiber reinforced plastic, etc. Is used.

The damping band 32 has an annular portion 102, and the outer peripheral side surface 102 a of the annular portion 102 has substantially the same diameter as the inner peripheral surface 22 b of the tensioner cup 22, and is close to the inner peripheral surface 22 b near the opening of the tensioner cup 22. Make sliding contact.

Referring to FIG. 4, the damping band 32
Are separated at the cutting portion 106, and are formed symmetrically with respect to the diameter (II line) including the cutting portion 106. The cutting portion 106 functions as a drainage portion for absorbing thermal deformation of the damping band 32 and for draining water that has entered the tensioner cup 22.

On the end face of the annular portion 102 on the tensioner arm 30 side, a crown 104 having a diameter larger than that of the annular portion 102 is formed. When attaching the damping band 32 to the tensioner cup 22, the lower surface 104a of the crown head 104
Contacts the end face of the opening of the tensioner cup 22.

Please refer to FIG. 5 and FIG. Annular part 102
The inner peripheral surface 102b of the
6 are formed opposite to each other. The arm engagement portion 110 protrudes in a hump shape toward the center in the radial direction of the annular portion 102.

Each of the two arm engaging portions 110 is formed with a mounting hole 112 penetrating in the axial direction. Each mounting hole 1
The axis of 12 is parallel to the pivot bolt 23. The two mounting holes 112 are eccentric with respect to the pivot bolt 23 and are formed at equal positions in the radial direction (see FIG. 4). The diameter of the mounting hole 112 is the tensioner arm 3.
0 is substantially the same as the outer diameter of the pin 30a.
The pins 30a are inserted into each of the pins 2 with substantially no gap (see FIG. 2). The fitting of the mounting hole 112 and the pin 30a restricts the relative movement of the damping band 32 in the rotation direction and the radial direction with respect to the tensioner arm 30.

Tensioner cup 2 of arm engaging portion 110
The corner 110c on the second side is rounded with a predetermined diameter. Further, on the support surface 110 a of the arm engaging portion 110 on the tensioner cup 22 side, two disk-shaped support protrusions 116 are provided on both sides of the mounting hole 112.
The rounded diameter of the corner portion 110c and the height of the support protrusion 116 may be formed to have the same length, and the length is not particularly limited.

Further, a cutting portion 106 is provided on the inner peripheral surface 102b.
And a belt-shaped projection 120 extending in the circumferential direction from the front side. As shown in FIG. 6, the projection 120 is formed such that the end face 120a on the tensioner cup 22 side is on the same plane P as the end face 116a of the support projection 116 (indicated by a two-dot chain line).

The ring receiver 122 is a belt-like projection extending in the circumferential direction on the inner peripheral surface 102b of the annular member 102.
It is formed between the protrusion 120 and the arm engaging portion 110.
With respect to the axial direction of the inner peripheral surface 102b, the ring receiver 122
It is located on the tensioner cup side (upper side in FIG. 6) with respect to the plane P. The corner portion 122c of the ring receiver 122 on the tensioner cup 22 side is rounded.

As shown in FIGS. 7 and 8, a C-shaped ring spring 33 is provided on the inner peripheral surface of the damping band 32.
Are attached in a state of being contracted in the radial direction. The plate width (diameter in the radial direction) of the ring spring 33 is gradually increased from the opening 106 toward the engagement portion 110. The ring spring 33 is in close contact with the inner peripheral surface 102a of the damping band 32, and is axially sandwiched between the ring receiver 122, the upper surface 116a of the support protrusion 116, and the upper surface 120a of the protrusion 120, as shown in FIG.

The two ring springs 33 urge the damping band 32 toward the tensioner cup 22 with a substantially uniform and constant pressure. As a result, when the tensioner arm 30 swings, a damping force due to frictional force is generated at a sliding contact portion between the damping band 32 and the tensioner cup 22. The biasing force of the ring spring 33 is
It is set appropriately according to the required damping force.

In the automatic tensioner of this embodiment, the tensioner arm 30 is rotated and biased by the biasing force of the torsion spring 50 to tension the drive belt 17 and the tensioner arm 30 swings due to the vibration of the drive belt 17 and the like. At this time, a damping force is generated by the urging force of the ring spring 33 at a portion where the outer peripheral surface 102a of the damping band 32 and the inner peripheral surface 22b of the tensioner cup 22 are in sliding contact with each other, thereby damping the vibration.

Although a large stress acts on the corner 110c of the damping band 32 due to the urging force generated at the time of swinging, no stress concentration occurs because the corner 110c is rounded. Also damping band 3
The ring spring 33 in the second arm engaging portion 110
Since the support protrusion 116 is provided on the support surface 110a that abuts on the corner portion 110c, the load applied to the corner 110c from the ring spring 33 can be reduced by the cushion effect, and the damping band 32 can be prevented from being damaged.

FIG. 9 shows another embodiment of the support projection. The support protrusion 152 is a band-shaped protrusion formed on the support surface 110a of the arm engaging portion 110 in the circumferential direction.
It is provided between 10c and the mounting hole 112. The upper surface 152a of the support protrusion 152 is the upper surface 1 of the opposing protrusion 120.
20a (see FIG. 6). Also in this embodiment, the ring spring does not come into contact with the corner portion 110c, and the corner portion 110c is reinforced by the roundness, so that an effect that the damping band is hardly damaged is obtained.

[0036]

According to the present invention, it is possible to provide an auto-tensioner having a damping band which hardly causes crack damage and has excellent durability.

[Brief description of the drawings]

FIG. 1 is a front view showing an auto tensioner of an embodiment together with a belt system of an automobile engine.

FIG. 2 is a cross-sectional view of the auto tensioner shown in FIG.

FIG. 3 is an exploded sectional view showing parts of the auto tensioner shown in FIG. 2;

FIG. 4 is a view of the damping band shown in FIG. 2 as viewed from a tensioner cup side (the lower side in FIG. 2).

FIG. 5 is a perspective view of the damping band shown in FIG. 4 taken along a line II in FIG. 4;

FIG. 6 is a cross-sectional view of the damping band shown in FIG. 4 taken along line II of FIG. 4;

FIG. 7 is a perspective view showing a state in which a ring spring is engaged with the damping band shown in FIG. 4 and is cut along line II of FIG. 4;

8 is a sectional view showing the damping band shown in FIG. 4 together with a ring spring, which is cut along the line II in FIG. 4;

FIG. 9 is a perspective view showing another embodiment of the engaging portion of the damping band shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Auto tensioner 11, 12, 13, 14, 15, 16 Pulley 17 Drive belt 22 Tensioner cup 23 Pivot bolt 30 Tensioner arm 30a Pin 32 Damping band 33 Ring spring 40 Tensioner pulley 50 Torsion spring 110 Engagement part 112 Hole 116 Support projection

Claims (4)

(57) [Claims] 1. A tensioner cup, a tensioner arm swingably attached to an opening of the tensioner cup, an annular portion slidable on an inner peripheral surface of the tensioner cup on an opening side, and an annular portion of the annular portion. A damping member formed to protrude inward from a part of the inner peripheral surface and having an arm engaging portion having a mounting hole to be fitted to a pin formed in the tensioner arm; and the tensioner arm of the arm engaging portion A ring spring that is provided on the support surface opposite to the first surface and biases the damping member toward the inner peripheral surface of the tensioner cup, and is formed between the support surface of the damping member and the annular portion. A roundness having a predetermined diameter is formed at the corner,
An auto tensioner characterized in that a ring spring engaging surface having a height corresponding to the diameter of the roundness is formed. 2. The auto tensioner according to claim 1, wherein a ring spring engagement surface is formed by a support projection provided on the support surface of the damping member. 3. The auto-tensioner according to claim 2, wherein a plurality of the support protrusions are provided on one arm engagement portion. 4. The auto-tensioner according to claim 2, wherein the support projection has a disk shape.