JP2001173737A - Auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dust, water, salt water, or the like from penetrating into a cup, in an auto tensioner, and prevent early abrasion of a damping member. SOLUTION: A seal member 70 is disposed in a clearance formed between an opening side end surface 13 of a cup and a cup side end surface 33 of an arm 30, and an inside of the cup 10 is tightly closed. A damping band 82 is housed in the cup 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tensioner used for a power transmission device of an internal combustion engine, for example.

[0002]

2. Description of the Related Art Generally, an automobile or the like is provided with a power transmission device for transmitting the rotation of a drive shaft of an engine to a driven shaft, for example, a plurality of auxiliary shafts such as an alternator and a cooler pump, by a single endless belt. The endless belt is given a constant tension by an auto tensioner. In recent years, fluctuations in the number of revolutions have increased with the performance of engines, and the length of the endless belt may be relatively long because it is hung between multiple accessories. ing. Therefore, a damping mechanism for damping the vibration of the endless belt is added to the auto tensioner.

[0003] Such an auto-tensioner includes, for example, a cup fixed in proximity to a belt, an arm rotatably mounted on the cup, and a pulley mounted on the end of the arm and in contact with an endless belt. Prepare. The arm is biased by a torsion coil spring housed in the cup in a fixed rotational direction, ie, in a direction in which the pulley tensions the endless belt. Further, a damping member formed of a synthetic resin or the like is fixed to the arm. When the arm rotates with the vibration of the endless belt, the damping member frictionally slides on the inner peripheral surface of the cup, and rotation resistance is given to the arm.

[0004]

In order to effectively attenuate the vibration of the endless belt, it is necessary to apply a predetermined rotational resistance to the arm, and it is required that the damping member always generate a constant frictional force. You. However, in a configuration in which the damping member is housed inside the cup, dust, water, salt water, or the like enters from a gap between the cup opening and the arm,
The damping member, which is a synthetic resin, may be quickly worn or damaged, and the frictional force of the damping member may not be stable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an automatic tensioner which prevents dust, water or salt water from entering a cup, and prevents early wear of a damping member. Is the purpose.

[0006]

SUMMARY OF THE INVENTION An auto-tensioner according to the present invention includes a cup-shaped member having a bottom and a cylindrical portion integrally extending from the bottom, and having a radius substantially equal to the outer radius of the opening of the cup-shaped member. A disk portion having the same radius and coaxially and rotatably mounted on the opening side of the cup-shaped member, and a predetermined distance from the annular opening-side end surface of the cup-shaped member provided on the outer edge of the disk portion An arm having an annular cup-side end face facing away from the arm, and an annular seal member provided over the entire circumference between the opening-side end face and the cup-side end face to seal the inside of the cup-shaped member. Features. Intrusion of dust, water, salt water, or the like into the cup can be prevented, and early damage of a synthetic resin material such as a damping member provided in the cup can be prevented.

The seal member of the auto tensioner is preferably formed of a synthetic resin material having a breaking elongation of at least 200%, and is in close contact with the opening side end face and the cup side end face in a state of being compressed in the axial direction. Is preferred. Since the seal member is formed of a material having a relatively large elongation at break, even if the seal member is in close contact with both the cup and the arm that rotates relative to the cup, early damage of the seal member itself is prevented. As the synthetic resin material, for example, an aliphatic polyketone having a breaking elongation of about 300 to 400% or a polyether-based elastomer having a breaking elongation of about 200 to 1000% is suitable.

The cross-sectional shape of the seal member may be a "<" shape in which the center of the cross-section in the axial direction projects toward the axial center, or may be a circular shape.

[0009] The seal member of the auto tensioner may be provided eccentrically with respect to the axis of the cup-shaped member. Thereby, it is possible to prevent unevenness in wear of the opening-side end surface, the cup-side end surface, and the seal member that is in close contact with these surfaces, and improve durability.

In the automatic tensioner, the arm may have an annular projection protruding from the outer edge of the cup-side end surface toward the opening-side end surface and having a gap with respect to the opening-side end surface. Is arranged, the seal member is positioned in the radial direction.

In the auto-tensioner, a torsion coil spring for biasing the arm in a predetermined rotation direction and a damping member for imparting rotational resistance to the arm are housed in a cup preferably sealed by the cup, the arm and the seal member. Is done. Since the inside of the cup is sealed, premature wear of the damping member is prevented.

[0012]

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.

FIG. 1 is a sectional view of an auto tensioner according to an embodiment. Auto tensioner is cup 10
The cup 10 is fixed to a predetermined position of an engine block (not shown). A flange 12 is formed over the entire opening of the cup 10, and an annular opening-side end face 13, which is the upper surface of the flange 12, is
It is located on a plane perpendicular to the 0 axis CL (indicated by a dashed line in the figure).

A fixing hole 14 for fixing the rotating shaft member 20 is formed in the center of the bottom 16 of the cup 10, and one end of the rotating shaft member 20 has a washer 15 in the fixing hole 14.
And is screwed and fixed.

The arm 30 has a disk portion 32 having a radius substantially equal to the radius of the outer periphery of the flange 12, and a washer 15 from the center of the disk portion 32 toward the bottom 16 of the cup 10.
The bearing portion 34 extending to the vicinity is integrally formed. The outer peripheral edge of the disk portion 32 protrudes toward the cup 10 over the entire circumference, and faces the opening-side end surface 13 of the cup 10 at a predetermined distance. An annular surface facing the opening side end surface 13 and perpendicular to the axis CL is called a cup side end surface 33. Further, the disk member 32 of the arm 30 is formed with an annular projection 40 projecting from the outer edge of the cup-side end surface 33 toward the opening-side end surface 13.

Bearing hole 3 penetrating in the axial direction of bearing portion 34
The rotary shaft member 20 is inserted into 6. A bearing member 38 made of synthetic resin is press-fitted into the bearing hole 36, and the bearing member 3
8 is in sliding contact with the outer peripheral surface of the rotating shaft member 20. Thereby, the arm 30 becomes rotatable around the axis CL.

The diameter of the head 22 of the rotary shaft member 20 is larger than the diameter of the bearing hole 36, and the relative movement of the disk portion 32 along the axis CL is regulated by the head 22. A flange 39 formed at the tip of the bearing member 38 is interposed between the head 22 and the disk portion 32.

As described above, the arm 30 is connected to the rotating shaft member 20.
, And is rotatable with respect to the cup 10 around the axis CL, and is fixed in the direction of the axis CL.

A pulley mounting portion 36 is provided integrally with the disk portion 32 of the arm 30. The pulley mounting portion 36 has a pulley bearing 37 projecting toward the opposite side (upward in the figure) of the cup 10. ing. A pulley 60 is mounted outside the pulley bearing 37, and the pulley bearing 37 and the pulley 6
Between 0 and 0, the ball bearing 62 is press-fitted. A washer 64 is fitted above the ball bearing 62 in the drawing, and a pulley bolt 66 is further inserted from above the washer 64 and screwed and fixed inside the pulley bearing 37. This restricts the relative movement of the ball bearing 62 and the pulley 60 along the pulley axis PL.

As described above, the pulley 60 is connected to the pulley bolt 6
6, it is rotatable around the pulley axis PL with respect to the arm 30 and is fixed in the pulley axis PL direction. The cylindrical outer peripheral wall 68 of the pulley 60 abuts on a belt (not shown). The pulley axis PL is parallel to the axis CL.

A torsion coil spring 50 is housed inside the cup 10. The torsion coil spring 50 is a metal wire having a circular cross section wound around the rotary shaft member 20, and both ends thereof are provided on the bottom portion 14 of the cup 10 and the arm 30.
Respectively.

The torsion coil spring 50 is interposed in the cup 10 while being twisted by a predetermined torsion force.
The belt is urged in a predetermined rotation direction, that is, a direction in which the belt that contacts the pulley 60 is tensioned. Thereby, an appropriate tension is applied to the belt.

A cylindrical damping band 82 is in sliding contact with the inner peripheral surface 18 near the opening of the cup 10 over substantially the entire circumference. A pin 83 extending toward the cup bottom surface 16 is formed in the disk portion 32 of the arm 30, and the pin 83 is pressed into a pin hole 85 of the damping band 82. Thereby, the damping band 82 is fixed to the arm 30 in the circumferential direction and the axis CL direction.

Outside the outer peripheral surface of the damping band 82, a flange 86 is integrally formed over substantially the entire periphery, and the flange 86 is formed on the opening end surface 13 in the direction of the axis CL.
And the cup-side end face 33. Therefore, the flange 86 is supported by the opening 12 of the cup 10 and the dropping of the damping band 82 to the cup bottom surface 16 is prevented.

The damping band 82 has a shaft center CL from the inside.
The two ring springs 84 are biased substantially uniformly in the circumferential direction toward the inner peripheral surface 18. When the arm 30 swings and rotates due to the vibration of the belt, the damping band 82 frictionally slides with the cup 10, and rotation resistance is given to the arm 30. Thereby, the rotation of the arm 30 is braked, and the vibration generated in the belt is effectively attenuated.

Although not shown, the damping band 8
The ring spring 2 and the ring spring 84 are partially broken in the circumferential direction, and the damping band 82 can be expanded and deformed in the radial direction. Thus, even if the sliding surface of the damping band 82 is worn due to frictional sliding with the inner peripheral surface 18, a gap with the inner peripheral surface 18 is prevented from being generated.

In a state where the arm 30 is attached to the cup 10 as shown in FIG.
There is a gap between the disk member 32 and the cup-side end surface 33, and an annular seal member 70 is provided in this gap.
On the outer peripheral side of the damping band 82, the sealing member 70 is
And the cup-side end surface 33 is in close contact with the entire circumference, and the inside of the cup 10 is sealed. That is, the damping band 82 is housed in a space closed by the cup 10, the arm 30, and the seal member 70.

FIG. 2 is a plan view of the seal member 70, and FIG. 3 is a partial cross-sectional view of the seal member 70.
It is sectional drawing in the II line. FIG. 4 is a partially enlarged view of FIG. 1 and shows a configuration near the seal member 70.

In FIG. 2, the axis which is the center of the seal member 70 in the radial direction is indicated by a point CK, and the axis CK is in the radial direction with respect to the axis CL of the cup 10 which is also the rotation axis of the arm 30. At a position separated by a minute distance ΔL. That is, the seal member 70 is mounted eccentrically with respect to the axis CL. The axis CL and the axis CK are parallel to each other.

The cross-sectional shape of the seal member 70 is in the shape of a square with a central cross-section 72 in the direction of the axis CK protruding toward the axis CK. The natural length S ₁ of the seal member 70 in the axial center CK direction is larger than the axial distance S ₂ between the opening-side end surface 13 and the cup-side end surface 33. The end face 74 on the cup 10 side and the end face 76 on the arm 30 side are annular flat surfaces perpendicular to the axes CL and CK, respectively.
And the cup-side end surface 33.

The tip of the end portion 78 on the end surface 76 side (upper side in the figure) is rounded, and the cup-side end surface 33 and the annular projection 4 are formed.
It can be in close contact with the round recess 40a between zero. End 78
And the rounded curvature of the round recess 40a are substantially the same.
In the radial direction perpendicular to the axis CL, the width S ₃ of the sealing member 70 is smaller than the distance S ₄ from the flange 86 of the damping band 82 to the round recess 40 a, and
Is positioned in the radial direction by the flange 86 and the round recess 40a. Eccentricity Δ of axis CK with respect to axis CL
L is less than the value from the distance S ₄ by subtracting the width S _3.

In short, the sealing member 70 is disposed between the opening-side end face 13 and the cup-side end face 33 in the direction of the axis CL, and is formed between the flange 86 and the annular projection 40 in the radial direction perpendicular to the axis CL. And is eccentric to the axis CL by a distance ΔL. The sealing member 70
The inside of the cup 10 is sealed by being compressed and closely attached to the opening-side end face 13, the cup-side end face 33 and the round recess 40a.

The arm 30 has an axis CL with respect to the cup 10.
When rotating relatively, the seal member 70 rotates around the axis CL, that is, eccentrically with respect to its own axis CK. Thereby, the sliding contact surface between the seal member 70 and the opening-side end surface 13 and the cup-side end surface 33 shifts by a very small amount according to the rotation. In the opening side end surface 13 or the cup side end surface 33,
Since the surface that slides on the seal member 70 is a part, if the axis CK of the seal member 70 is aligned with the rotation axis CL, only the part that slides on the seal member 70 is worn. However, in the present embodiment, since the axis CK of the seal member 70 is eccentric with respect to the rotation axis CL, the seal member 7
The surface that comes into sliding contact with 0 moves within the range between the flange 86 and the annular projection 40, and unevenness of wear on the opening-side end surface 13 or the cup-side end surface 33 is prevented. Accordingly, uneven wear of the seal member 70 is also prevented, and its durability is improved.

The sealing member 70 has a large breaking elongation,
A material having good durability under repeated load and excellent in abrasion resistance is preferable. In the present embodiment, the seal member 70 is formed of a synthetic resin material having a breaking elongation of at least 200%, and an aliphatic polyketone having a breaking elongation of about 300 to 400% or a polyether-based material having a breaking elongation of about 200 to 1000%. Elastomers are preferably used. Although the seal member 70 is molded by a known injection molding method, the molding method is not particularly limited. As a material of the seal member 70, a rubber-based material is generally known,
Since rubber-based materials have a large coefficient of friction, a lubricant such as grease is indispensable to prevent premature wear. Nylon-based materials have low elongation and poor resistance to calcium chloride solution, and therefore are not suitable for the material of the seal member 70. The above-mentioned aliphatic polyketone or polyether-based elastomer is a material having good elongation and having a resistance to calcium chloride solution, and is most suitable for the material of the sealing member 70.

As described above, according to the auto-tensioner of the present embodiment, the opening-side end face 13 of the cup 10 and the arm 3
By providing the seal member 70 in the gap between the cup 10 and the cup-side end surface 33, the inside of the cup 10 is sealed to prevent entry of dust, water or salt water, and the synthetic resin damping housed in the cup 10 Premature wear and breakage of the band 82 can be prevented.

The cross-sectional shape of the seal member 70 is
, But may be a circle as shown in FIG. Also in this case, the length S _{1 in} the direction of the axis CL, that is, the diameter of the circle is set to be larger than the distance S ₂ .

[0037]

According to the present invention, it is possible to prevent dust, water, salt water or the like from entering the cup of the auto tensioner, thereby preventing early wear of the damping member.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an auto tensioner according to the present invention.

FIG. 2 is a plan view of a seal member.

FIG. 3 is a partial sectional view of the seal member taken along line III-III in FIG. 2;

FIG. 4 is a view showing a configuration near a seal member, and is a partially enlarged view of FIG. 1;

FIG. 5 is a view showing another cross-sectional shape of the seal member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cup 12 Flange 13 Opening end face 16 Bottom part 30 Arm 32 Disk part 33 Cup side end face 40 Annular projection 50 Torsion coil spring 70 Sealing member 82 Damping band

Claims (9)

[Claims] 1. A cup-shaped member having a bottom portion, a cylindrical portion integrally extending from the bottom portion, and the cup-shaped member having a radius substantially equal to a radius of an outer periphery of an opening of the cup-shaped member. A disk portion coaxially and rotatably mounted on the opening side of the disk-shaped member, and an annular portion provided on an outer edge of the disk portion and spaced apart from the annular opening-side end surface of the cup-shaped member by a predetermined distance. An auto having an arm having a cup-side end surface; and an annular seal member provided over the entire circumference between the opening-side end surface and the cup-side end surface and sealing the inside of the cup-shaped member. Tensioner. 2. The sealing member is formed of a synthetic resin material having a breaking elongation of at least 200%, and is in close contact with the opening-side end surface and the cup-side end surface in a state of being compressed in the axial direction of the cup-shaped member. The auto-tensioner according to claim 1, wherein: 3. The auto-tensioner according to claim 2, wherein the synthetic resin material is an aliphatic polyketone. 4. The auto tensioner according to claim 2, wherein the synthetic resin material is a polyether-based elastomer. 5. The auto tensioner according to claim 1, wherein the seal member is provided eccentrically with respect to an axis of the cup-shaped member. 6. The cross-sectional shape of the seal member according to claim 1, wherein the cross-sectional shape of the cup in the axial direction of the cup has a “<” shape protruding toward the axial center. Auto tensioner. 7. The auto-tensioner according to claim 1, wherein a cross-sectional shape of the seal member is circular. 8. The arm includes an annular projection protruding from an outer edge of the cup-side end surface toward the opening-side end surface and having a gap with respect to the opening-side end surface. By disposing the sealing member,
The auto-tensioner according to claim 1, wherein the seal member is positioned in a radial direction. 9. A torsion coil spring for urging the arm in a predetermined rotation direction inside the cup sealed by the cup, the arm and the seal member, and a damping member for imparting rotational resistance to the arm. The auto-tensioner according to claim 1, wherein is stored.