JP3253944B2 - 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 automatic tensioner for applying an appropriate tension to a drive transmission device using an endless belt.

[0002]

2. Description of the Related Art Conventionally, in a drive transmission device for a vehicle engine or the like, a single endless belt is wound around a drive pulley and a driven pulley, and an automatic tension is applied to the endless belt to apply an appropriate tension. A tensioner is often used. The auto-tensioner not only has a function of abutting on the endless belt to apply a constant tension, but also has a function of attenuating vibration generated in the endless belt.

In such an auto tensioner, a rotating shaft member is fixed to a cup-shaped member fixed to a predetermined portion of an engine block, an arm is rotatably mounted on the rotating shaft member, and furthermore, the arm is eccentric from the rotating shaft center of the arm. A pulley that comes into contact with the endless belt is attached to the position where it was set. The arm is urged by a torsion coil spring provided inside the cup-shaped member in a direction to tension the endless belt,
Vibration received from the endless belt via the pulley is damped by a friction member provided between the arm and the cup-shaped member.

[0004] Appropriate bearing members are provided between the arm and the pulley and between the arm and the rotary shaft member. Generally, a ball bearing is provided between the arm and the pulley, and a cylindrical member made of synthetic resin is provided between the arm and the rotating shaft member.

[0005]

In recent years, downsizing of an auto-tensioner has been required along with downsizing of an engine or an auxiliary machine, and furthermore, in order to drive a plurality of auxiliary machines with a single endless belt, it is necessary to further reduce the size of the auto tensioner. There is a demand for a function capable of withstanding a high load and effectively damping vibration. In particular,
It is possible to improve the durability of the ball bearing and the cylindrical member that are the bearing members.

In order to meet such a demand, for example, it is conceivable to reduce the distance between mutually parallel axes of the arm and the pulley. In this case, a rotating shaft for rotatably supporting the arm or the arm is considered. The position in the axial direction needs to be separated from the pulley so that the member does not hinder the rotation of the pulley. However, in a configuration in which the positions of the rotating shaft member and the pulley in the axial direction are shifted from each other, the bias of the load applied from the pulley to the arm becomes large, the arm is easily inclined, and the ball bearing and the cylindrical member may be damaged.

The present invention has been made in view of such a point, and has improved durability durability of a bearing member provided between an arm and a pulley and between an arm and a rotary shaft member. It is an object to provide a small auto tensioner.

[0008]

An auto-tensioner according to the present invention comprises a rotary shaft member fixed at a predetermined position around an axis and in an axial direction for rotatably fixing an arm to which a pulley is attached. A member inserted into a shaft hole formed in the arm; and a cylindrical portion integrally provided at one end of the cylindrical portion and having a diameter larger than the diameter of the shaft hole, and having a diameter greater than the diameter of the shaft hole. and a circular plate portion for restricting a relative movement along the, I at least 1.8 Baidea diameter diameter cylindrical portion of the disc portion, of the inner peripheral wall member of the pulley a
Between the arm end and the pulley end of the arm.
Part of the disc portion of the wood is characterized that you have entered. In this manner, the disk portion having a relatively large diameter with respect to the column portion regulates the relative movement of the arm in the axial direction, so that the arm is prevented from tilting and the arm and the pulley or between the arm and the rotary shaft member are prevented from tilting. It is possible to improve the durability reliability of the bearing member provided on the vehicle.

In the auto tensioner, a bearing member may be provided between the arm and the rotating shaft member. The bearing member includes a cylindrical portion interposed between the arm and the column portion, and a disk portion of the cylindrical portion. It is preferable to include a flange formed integrally with the side end and having a diameter of the outer periphery relatively smaller than the diameter of the disk portion. The bearing member is formed of a material having excellent wear resistance, for example, a resin material containing polytetrafluoroethylene (PTFE), so that the arm can rotate with respect to the rotating shaft member, and the disk portion and the arm Interference is avoided.

The auto tensioner may include a cup-shaped member. The other end of the column is press-fitted and fixed at the center of the bottom of the cup-shaped member, and an arm is provided at the opening of the cup-shaped member. . Thereby, a torsion coil spring, a friction member, and the like can be housed inside the cup-shaped member, and downsizing can be realized. In such a configuration,
Preferably, the pulley is provided on the opposite side of the cup-shaped member with respect to the arm, and rotates around a pulley axis parallel to the axis of the rotary shaft member.

In the automatic tensioner, preferably,
The arm has an arm end surface perpendicular to the axis of the rotating shaft member,
The flange portion of the bearing member is in close contact with the end surface of the arm, and the disk portion of the rotating shaft member is in close contact with the flange portion. Thereby, the relative movement along the axial direction of the arm is restricted.

In the automatic tensioner, preferably,
The pulley has a cylindrical inner peripheral wall member and an outer peripheral wall member having the pulley axis as an axis, and in the axial direction, the pulley-side end surface of the disk portion is cup-shaped from the cup-shaped member-side end of the inner peripheral wall member. It is located on the member side. Thus, the rotation of the pulley does not hinder the rotation of the pulley, and the size of the auto tensioner can be reduced.

Furthermore, the end face of the disk portion of the rotary shaft member on the pulley side may be located closer to the cup-shaped member than the end portion of the outer peripheral wall member on the cup-shaped member side. Thus, even when the radius of the pulley is smaller than the distance between the axis of the rotary shaft member and the pulley axis, the pulley can rotate without interfering with the rotary shaft member.

In the auto tensioner, the pulley may include an annular plate member extending radially from the end of the inner peripheral wall member on the cup-shaped member side toward the pulley axis. Accordingly, when the pulley is formed by the pressing process, the forming accuracy is improved, and the roundness of the inner peripheral wall member is improved. Therefore, when the ball bearing is fixed between the inner peripheral surface of the inner peripheral wall member and the arm, the radial clearance set in the ball bearing can be secured at any position in the circumferential direction, and the durability of the ball bearing is improved. I do.

Further, the cup-shaped member side end of the inner peripheral wall member, which is the connecting portion of the inner peripheral wall member and the annular plate member, is rounded, and the corner of the ball bearing facing the cup-shaped member side end is rounded. In this case, the radius of curvature of the cup-shaped member side end is set to be smaller than the radius of curvature of the corner, and the annular plate member faces the ball bearing with a predetermined gap. This facilitates the press forming of the pulley, further improves the roundness of the inner peripheral wall member, avoids the interference between the ball bearing and the end of the cup-shaped member of the inner peripheral wall member, and reduces the radial clearance of the ball bearing. Can be secured and its durability is improved.

[0016]

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 shows an automatic tensioner according to an embodiment. The auto tensioner includes a cup 10 which is a cup-shaped member, and the cup 10 has two mounting holes 12 provided on the side on the bottom side. These mounting holes 12
The cup 10 is fixed to a predetermined position of an engine block (not shown).

A hole 14 for fixing the rotating shaft member 20 is formed in the center of the bottom surface of the cup 10, and one end of the cylindrical portion 22 of the rotating shaft member 20 is press-fitted and fixed in the hole 14. On the free end side of the cylindrical portion 22, a disk portion 24 having a larger diameter than the cylindrical portion 22 is provided integrally.

The arm 30 is a substantially disk-shaped metal member, and is attached to the opening 16 of the cup 10. The arm 30 has a bearing portion 31 extending toward the bottom surface of the cup, and a bearing hole 3 penetrating through the bearing portion 31 in the direction of the axis CL.
2, the rotary shaft member 20 is inserted. In FIG. 1, the axis CL indicated by a chain line coincides with the axis of each of the cup 10, the rotating shaft member 20, and the bearing hole 32. In the axis CL direction, the bearing hole 32 is provided over about 2/3 of the axis length of the cylindrical portion 22, so that the load received from the arm 30 by the rotating shaft member 20 in the axis CL direction is It is dispersed and the fall due to the local load burden is prevented.

The diameter D ₁ of the disk portion 24 is larger than the diameter D ₃ of the bearing hole 32 (FIG. 3), so that the arm 30 is rotatably supported by the rotary shaft member 20 and the opening 16 and the disk The relative movement in the direction of the axis CL is regulated by the portion 24.

Two bearing members 40 and 50 are press-fitted into the bearing hole 32 from the upper end and the lower end, respectively, and they are in sliding contact with the outer peripheral surface of the rotating shaft member 20. Thereby, the arm 30 becomes rotatable around the axis CL. Bearing member 4
As materials of 0 and 50, synthetic resin excellent in abrasion resistance,
For example, a resin material containing polytetrafluoroethylene (PTFE) is suitable.

The bearing member 40 includes a cylindrical portion 22 and a bearing hole 32.
And a flange portion 44 formed integrally with one end of the cylindrical portion 42 and in contact with the disk portion 24 and the flat end surface 34 of the arm 30. The bearing member 50 has the same configuration as the bearing member 40 except that the position and the size of the flange portion 54 are different, and the details are omitted. The diameter of the outer periphery of the flange 54 is substantially the same as the diameter of the outer periphery of the lower end of the bearing 31.

A pulley mounting portion 36 protruding toward the pulley 60 is integrally provided at the pulley 60 side of the arm 30, that is, at one end of the upper end surface 34 in the drawing. A pulley 60 is mounted on the outside of the pulley mounting portion 36 via a ball bearing 68, and the pulley 60 is obtained by press-molding a metal member.

The pulley 60 has two cylindrical portions, both of which have the pulley axis PL as axes. The inner cylindrical member having a small inner diameter, which is an inner peripheral wall member, is divided into an inner peripheral wall 62 and an inner peripheral wall 62, which is an outer peripheral wall member. The outer cylindrical portion is called an outer peripheral wall 64. The inner peripheral wall 62 and the outer peripheral wall 64 are opposite to the arm 30 on the opposite side of the cup 10, that is, the upper ends 62a, 64a in the figure.
Are connected to each other by a first annular plate portion 66.

Further, the pulley 60 is integrally provided with a second annular plate portion 67 which is an annular plate member extending radially from the end portion 62b of the inner peripheral wall 62 on the cup 10 side toward the pulley axis PL. In addition, an end portion 62b, which is a connection portion between the inner peripheral wall 62 and the second annular plate portion 67, is rounded to facilitate press molding. As described above, the second annular plate portion 67 is provided integrally with the inner peripheral wall 62, that is, the end portion 6.
By forming 2b into an L-shaped cross section, the section modulus in the radial direction of the inner peripheral wall 62 is increased, and the molding accuracy of the inner peripheral wall 62 at the time of press molding, particularly, the roundness of the inner peripheral surface is improved.

The ball bearing 68 is connected to the pulley mounting portion 36.
And the inner peripheral wall 62 is press-fitted, whereby the pulley 60 is rotatable around the pulley axis PL with respect to the arm 30. A washer 72 is fitted above the ball bearing 68 in the drawing, and a pulley bolt 70 is further fitted from above the washer 72 and screwed and fixed to the pulley mounting portion 36. This restricts the relative movement of the ball bearing 68 and the pulley 60 along the pulley axis PL.

The second annular plate portion 67 of the pulley 60 faces the ball bearing 68 with a predetermined gap K (FIG. 3). A corner portion 68a of the ball bearing 68 faces the end portion 62b of the inner peripheral wall 62.
a is rounded over the entire circumference. The roundness of the corner 68a has a larger curvature than the roundness of the end 62b, that is, has a smaller diameter than the roundness of the end 62b.

A ball bearing 68 is provided inside the inner peripheral wall 62.
It is necessary to secure a predetermined radial gap set in the ball bearing 68 at any position in the circumferential direction. For this reason, in the present embodiment, the roundness of the inner peripheral wall 62 is improved by providing the second annular plate portion 67, whereby a predetermined radial gap can be secured, and the durability of the ball bearing 68 is improved.

As described above, by providing the second annular plate portion 67 integrally with the inner peripheral wall 62, the section modulus in the radial direction of the inner peripheral wall 62 is increased, and the roundness is improved.
On the other hand, the end 62b of the L-shaped cross section or the second annular plate 67 approaches the corner 68a and easily interferes. End 6
When 2b interferes with the corner 68a, the ball bearing 68
A predetermined radial gap required for the ball bearing 68 cannot be obtained, and the life of the ball bearing 68 is shortened. However, in the present embodiment, a predetermined curvature K is provided between the second annular plate portion 67 and the ball bearing by making the rounded curvature of the corner portion 68a larger than the rounded curvature of the end portion 62b. This prevents interference between the end 62b and the corner 68a. Therefore, a predetermined radial clearance of the ball bearing 68 can always be ensured, and the durability of the ball bearing 68 is improved.

The arm 30 is urged by a torsion coil spring 80 housed in the cup 10 in a predetermined rotational direction, that is, in a direction to tension an endless belt (not shown) that contacts the pulley 60. Thereby, an appropriate tension is applied to the endless belt.

On the inner peripheral surface of the cup 10 near the opening 16, a cylindrical damping band 82 is formed over substantially the entire circumference.
Are in sliding contact. This damping band 82 is used for the arm 3
And is urged by two ring springs 84 from the inside toward the inner peripheral surface of the cup 10, that is, in the direction in which the diameter increases. Arm 30 due to endless belt vibration
Swings (rotates), the damping band 82 frictionally slides with the cup 10, and the rotation of the arm 30 is suppressed. Thereby, the vibration generated in the endless belt is attenuated.

FIG. 2 is a front view of the rotating shaft member 20.
The rotating shaft member 20 is formed of a metal member and has a cylindrical portion 22.
And the disk part 24 is integrally formed. Disc portion 24 has a diameter D _1, is formed from the middle in the axial CL direction to the pulley side end surface 24a frustoconical whose diameter toward (upward direction in the figure) is gradually reduced. The diameter D ₁ of the disc portion 24 is at least 1.8 times the diameter d of the column portion 22.

The shoulder 26, which is the connection between the column 22 and the disk 24, is rounded to improve the strength. Further, the outer peripheral edge 27 of the disk portion 24 on the cup 10 side (the lower side in the figure) is also rounded. In the disk portion 24, an annular surface (shown by a straight line in the figure) between the shoulder portion 26 and the outer peripheral edge portion 27 is defined as a cup-side end surface 24b. The pulley side end surface 24a and the cup side end surface 24b are planes perpendicular to the axis CL.

[0034] As shown in FIG.
In the case of a configuration in which the arm 30 is attached to one end, there is a problem that the load applied to the arm 30 is not constant around the axis CL and the arm 30 is easily inclined with respect to the axis CL. When the arm 30 is tilted, the amount of wear of the flange portion 44 provided between the arm 30 and the disk portion 24 increases, the thickness in the direction of the axis CL decreases, and the strength decreases. For this reason, a gap may be formed between the arm 30 and the disk portion 24 to not only promote the inclination of the arm 30 but also cause the generation of abnormal noise and the premature breakage of the flange portion 44. Therefore, in the present embodiment, the disk portion 24 having a diameter at least 1.8 times the diameter d of the cylindrical portion 24 is formed by integral processing, whereby the supporting area for the arm 30 can be relatively increased, The inclination of the arm 30 can be suppressed.

FIG. 3 is a partially enlarged view of FIG. Shaft center C
In the direction perpendicular to L, a part of the disk portion 24 and a part of the flange portion 44 have entered between the end portion 62b of the inner peripheral wall 62 of the pulley 60 and the end surface 34 of the arm 30. Part 2
4 and a dashed line EL indicating the left end of the flange portion 44, respectively.
1 and EL2 are moved closer to the pulley axis PL than a dashed line EL3 indicating the position of the outer periphery of the inner peripheral wall 62. This is because the thickness of the disk portion 24 is relatively thin, and the pulley side end surface 24a of the disk portion 24 is located closer to the cup 10 (the lower side in the figure) than the end portion 62b of the inner peripheral wall 62 in the axis CL direction. It is. Therefore, the shaft center CL can be brought closer to the pulley shaft center PL side, and the entire auto tensioner can be downsized.

As described above, if the thickness of the disk portion 24 is relatively reduced, the size of the auto tensioner can be reduced, but the supporting force of the arm 30 in the direction of the axis CL decreases. Therefore, if the arm 30 is inclined or vibrates along the axis CL due to the vibration of the endless belt,
The flange 44 of the bearing member 40 made of synthetic resin is easily damaged. However, in the present embodiment, the area for receiving the load in the direction of the axis CL is increased by setting the diameters of the disk portion 24 and the flange portion 44 to be relatively large, so that the early damage of the flange portion 44 is prevented. Is done.

The bearing member 40 has a rounded portion (reference numeral 45) facing the shoulder portion 26 of the rotary shaft member 20. The curvature of the roundness 45 of the bearing member 40 is smaller than the curvature of the shoulder portion 26. It is small and mutual interference of the shoulder 26 and the roundness 45 is prevented.

The diameter D ₂ of the outer peripheral surface 44a of the flange portion 44 is set smaller than the diameter D ₁ of the disc portion 24, the more precisely, in the direction perpendicular to the axis CL, the outer peripheral surface of the flange portion 44 44a is a rounded outer peripheral portion 27 of the disk portion 24
It is located closer to the axis CL. In FIG. 3, the position of the outer peripheral surface 44a in the direction perpendicular to the axis CL is indicated by a chain line EL.
The position where the outer peripheral edge 27 starts to be rounded is indicated by a dashed line EL5.

As described above, the flange portion 44 is entirely in close contact with the cup-side end surface 24b of the disk portion 24 in the radial direction up to the outer peripheral surface 44a. The arm 30 is protected by dust and water, salt water, etc., from entering the flange 44, and the local load on the flange by the outer peripheral edge 27 of the disk portion 24 when the arm 30 is tilted is reduced. You. Therefore, the outer peripheral surface 44a of the flange 44
Can be prevented from being easily cracked from the corners of.

As described above, according to the first embodiment of the present invention, the diameter D _{1 of the} disk portion 24 which receives the load of the arm 30.
Is relatively large (at least 1.8 times the diameter d of the cylindrical portion 22), the inclination of the arm 30 is prevented, and the durability of the ball bearing 68 and the bearing members 40 and 50 can be improved.

FIG. 4 is a view showing an auto-tensioner according to a second embodiment of the present invention, and is a view showing a partially enlarged cross section. The auto-tensioner of the second embodiment has the same configuration as that of the first embodiment except that the relative position of the outer peripheral wall 64 of the pulley 60 is different, and the same components are denoted by the same reference numerals and description thereof is omitted.

In the direction of the axis CL, the position of the end surface 64b of the outer peripheral wall 64 on the cup 10 side is indicated by a dashed line BL1, and the position of the pulley side end surface 24a of the disk portion 24 is indicated by a dashed line BL2. In FIG. 4, a dashed line BL1
Are located above the alternate long and short dash line BL2, in other words, the end face 64b is provided above the pulley side end face 24a.
Therefore, the position of the outer peripheral surface of the outer peripheral wall 64 indicated by the one-dot chain line GL is more than the outer peripheral surface of the disk portion 24 indicated by the one-dot chain line EL6.
It can be moved to the pulley shaft center PL side (left side in the figure).

As described above, in the second embodiment, the radius X _{1 of the} pulley 60 can be set smaller than the distance X ₂ from the pulley axis PL to the outermost peripheral surface of the disk portion 24 (the dashed line EL6). Thus, the diameter of the pulley 60 can be reduced. In the second embodiment, as in the first embodiment, the diameter D of the disk portion 24 receiving the load of the arm 30 is also determined.
₁ is relatively large, the arm 30 is prevented from tilting, and the ball bearing 68 and the bearing member 4
Needless to say, the durability of 0 and 50 can be improved.

[0044]

According to the present invention, both miniaturization of the auto tensioner and prevention of damage to the bearing member can be realized, and the durability of the entire auto tensioner can be improved.

[Brief description of the drawings]

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

FIG. 2 is a front view of a rotating shaft member of the auto tensioner shown in FIG.

FIG. 3 is a partially enlarged view of FIG. 1 and is a cross-sectional view showing the vicinity of a disk portion of a rotating shaft member.

FIG. 4 is a view showing a second embodiment of the auto tensioner according to the present invention, and is a view showing a partially enlarged cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cup 20 Rotary shaft member 22 Column part 24 Disk part 30 Arm 40, 50 Bearing member 44, 54 Flange part 60 Pulley CL axis PL PL pulley axis

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H ^7/ 00-7/24 F02B 67/06

Claims (9)

(57) [Claims] 1. A rotary shaft member fixed at a predetermined position around an axis and in an axial direction for rotatably fixing an arm to which a pulley is attached, wherein the rotary shaft member has a shaft hole formed in the arm. And a cylindrical portion which is integrally provided at one end of the cylindrical portion and has a diameter larger than the diameter of the shaft hole, and regulates relative movement of the arm along the axial direction of the rotary shaft member. A disc portion, wherein the diameter of the disc portion is at least 1.
What 8 Baidea, an arm-side end of the inner peripheral wall member of said pulley of said arm
Between the pulley side end surface and the disk portion of the rotary shaft member
Auto tensioner part is characterized that you have entered. 2. A bearing member is provided between said arm and said rotary shaft member, said bearing member comprising a cylindrical portion interposed between said arm and said column portion, and said disk of said cylindrical portion. The auto-tensioner according to claim 1, further comprising: a flange portion formed integrally with the outer end portion and having a diameter of an outer periphery relatively smaller than a diameter of the disk portion. 3. A cup-shaped member, wherein the other end of the column is press-fitted and fixed at the center of the bottom of the cup-shaped member, and the arm is provided at an opening of the cup-shaped member. The auto-tensioner according to claim 2, wherein: 4. The apparatus according to claim 3, wherein the pulley is provided on the opposite side of the cup-shaped member with respect to the arm, and rotates around a pulley axis parallel to the axis of the rotary shaft member. Auto tensioner as described in. 5. The arm has an arm end face perpendicular to the axis of the rotary shaft member, the flange of the bearing member is in close contact with the arm end face, and the arm of the rotary shaft member is further attached to the flange. The auto-tensioner according to claim 4, wherein the close contact of the disc portion restricts the relative movement of the arm along the axial direction. Further comprising: a cylindrical within said peripheral wall member and an outer peripheral wall member on which the pulley and the axis of the pulley axis, the axis in the center direction, the inner peripheral wall member pulley side end surface of the circular plate portion The auto-tensioner according to claim 5, wherein the auto-tensioner is located closer to the cup-shaped member than the end of the cup-shaped member. 7. The auto tensioner according to claim 6, wherein an end surface of the disk portion on a pulley side is located closer to the cup-shaped member than an end of the outer peripheral wall member on a cup-shaped member side. 8. The pulley includes an annular plate member extending radially from the cup-shaped member side end of the inner peripheral wall member toward the pulley axis, and a ball bearing is provided between the inner peripheral wall member and the arm. The auto tensioner according to claim 1, wherein? 9. A cup-shaped member-side end of the inner peripheral wall member, which is a connection portion between the inner peripheral wall member and the annular plate member, and a corner of the ball bearing opposed to the cup-shaped member side end. Part is rounded, and the radius of curvature of the cup-shaped member side end is set smaller than the radius of curvature of the corner, and the annular plate member faces the ball bearing with a predetermined gap. The auto-tensioner according to claim 7, wherein: