JP3916973B2 - Auto tensioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an auto tensioner for automatically and appropriately maintaining the tension of a transmission belt of a belt drive mechanism having a damping mechanism.
[0002]
Conventionally, this type of auto tensioner is disclosed, for example, in US Pat. No. 4,696,663. In this case, the end of the spring is brought into contact with the brake shoe, the brake shoe is brought into close contact with the inner peripheral wall of the arm, and the arm is rotated by the frictional force generated between the brake shoe and the inner peripheral wall surface of the arm. It is a thing which makes damping work.
[0003]
Some are disclosed in Japanese Patent Application Laid-Open Nos. 9-189347 and 9-189348. In this structure, the end of the spring is brought into contact with the brake shoe, the brake shoe is brought into close contact with the inner peripheral wall of the arm, and the frictional force generated between the brake shoe and the inner peripheral wall surface of the arm causes the rotation of the arm. The damping mechanism that applies damping to the motion is substantially the same as that disclosed in the aforementioned US Pat. No. 4,696,663. Japanese Patent Laid-Open No. 9-189347 and Japanese Patent Laid-Open No. 9-189348 disclose a normal force in which the contact surface of the brake shoe that contacts the end of the spring is larger than the spring force that acts on the brake shoe. Is generated to increase the damping efficiency.
[0004]
[Problems to be solved by the invention]
However, in these conventional damping mechanisms, a brake shoe such as a brake material used in a bicycle is used, and the force from the spring end is transmitted to the brake shoe to apply the brake. In addition, because the brake shoe is locally in contact with the inner peripheral wall surface of the arm, it is difficult to always apply a normal force from the end of the spring to the brake shoe. Become. In addition, there is a problem that the brake shoe is unevenly worn and the damping efficiency is deteriorated in a short time.
[0005]
The present invention has been made in view of the above problems, and an object thereof is to provide an auto tensioner that can suppress uneven wear of a brake shoe and maintain high damping efficiency over a long period of time.
[0006]
[Means for Solving the Problems]
An auto tensioner according to claim 1 of the present invention for solving the above-described problem has a base on which a shaft is erected and a boss portion rotatably inserted into the shaft, and extends toward the base. An existing cylindrical member, a pulley rotatably mounted at an eccentric position of the cylindrical member, and one end of the cylindrical member in contact with the cylindrical member in a compressed state. A torsion spring, and a bendable arc-shaped friction member having one end fixed to the base and disposed along the inner peripheral surface of the cylindrical member, the bottom surface of which is in contact with the bottom plate of the base. A friction member whose side surface comes into contact with the inner peripheral surface of the cylindrical member, and the other end of the friction member and the other end of the torsion spring are engaged with each other, and the torsional force of the torsion spring According to the above And a engaging portion for widening the side of member abutting direction of the circumferential inside said cylindrical member, said portion extending to the other end of the spring in the compressed state is facing the friction member to the bottom plate portion It is characterized by pushing.
[0007]
According to the above configuration, when the cylindrical member is twisted in the direction in which the torsion spring spreads, the torsional force is transmitted to one end of the friction member, and the friction member tries to spread with respect to the inner periphery of the cylindrical member. The friction member is pressed in a wide range on the inner periphery of the cylindrical member. Therefore, the braking effect is good and an excellent damping effect can be obtained.
[0008]
An auto tensioner according to a second aspect is the auto tensioner according to the first aspect, wherein the friction member is disposed along 270 ° or more of an inner circumference of the cylindrical member.
[0009]
According to the said structure, a friction member is arrange | positioned along most inner periphery of a cylindrical member, and a friction member will be in a press-contact state in the wide range of the inner periphery of a cylindrical member. For this reason, it is possible to suppress uneven wear of the friction member.
[0010]
According to a third aspect of the present invention, in the auto tensioner according to the second aspect, one end of the friction member is fixed to the base by being abutted against a stopper standing on the base.
[0011]
According to said structure, a friction member can be easily arrange | positioned along a cylindrical member inner periphery.
[0012]
An auto tensioner according to a fourth aspect of the present invention is the auto tensioner according to the third aspect, wherein the friction member has an L-shaped cross section.
[0013]
According to the said structure, the arrangement | positioning state along the cylindrical member inner periphery of a friction member is stabilized. Further, the contact area of the inner periphery of the cylindrical member of the friction member can be increased, and the braking effect can be ensured.
[0014]
The autotensioner according to a fifth aspect of the present invention is the autotensioner according to the third aspect, wherein the friction member is formed of a synthetic resin of any one of polyamide, ultrahigh molecular weight polyethylene, and polytetrafluoroethylene.
[0015]
According to the above configuration, the friction member can be easily formed by integral molding.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, the auto tensioner 1 includes a base 3 on which a shaft 2 is erected, a boss portion 4 that is rotatably inserted into the shaft 2, and a cylindrical member 5 that extends toward the base 3; A pulley 6 rotatably mounted at an eccentric position of the cylindrical member 5; a torsion spring 7 housed inside the cylindrical member 5 in an axial direction and having one end 22 in contact with the cylindrical member 5; One end 14 is fixed to the base 3, a bendable arc-shaped friction member 9 disposed along the inner peripheral surface 8 of the cylindrical member 5, the other end 16 of the friction member 9, and the other of the torsion spring 7. An engagement portion 10 is provided for engaging the end portion 17 and expanding the friction member 9 in a contact direction to the inner periphery of the cylindrical member 5 in accordance with the torsional force of the torsion spring 7.
[0017]
The base 3 includes a shaft 2 erected along the axial center, a first step portion 11 formed at the base of the shaft 2, eccentric in a cam shape, a concentric second step portion 12, and a bottom plate portion 13. It consists of and. The first step portion 11 is formed so as to be eccentric in a cam shape, thereby holding the torsion spring 7 so as not to be displaced in the cylindrical member 5. The second step portion 12 positions the friction member 9 provided in contact with the bottom plate portion 13 so that the friction member 9 is disposed in a stable state in the cylindrical member 5.
[0018]
As shown in FIG. 2, the friction member 9 is formed in a C shape and is disposed along the inner peripheral surface 8 of the cylindrical member 5 along 270 ° or more, preferably 300 ° or more, more preferably 330 ° or more. ing. The friction member 9 is integrally formed of a synthetic resin of polyamide, ultrahigh molecular weight polyethylene, or polytetrafluoroethylene. Further, the friction member 9 has an L-shaped cross section, and the bottom surface side comes into contact with the bottom plate portion 13 of the base 3 and the side surface side comes into contact with the inner peripheral surface 8 of the cylindrical member 5. For this reason, it comes into surface contact with the inner peripheral surface 8 of the cylindrical member 5 reliably, and uneven wear is suppressed.
The friction member 9 is preferably formed in a C shape as shown in FIG. 2, but is arranged so that a linear object is inserted along the inner peripheral surface 8 of the cylindrical member 5. It is also possible to do. Further, as the friction member 9, in addition to the above-described integrally molded product made of synthetic resin, a metal plate spring lined with synthetic resin can also be used.
[0019]
One end 14 of the friction member 9 is fixed in contact with a stopper means 15 erected on the base 13 of the base 3 (see FIG. 3). On the other hand, the other end 16 is engaged with the end portion 17 of the torsion spring 7 to constitute the engaging portion 10.
[0020]
As shown in FIG. 1, the cylindrical member 5 includes a boss portion 4 that is rotatably inserted into a shaft 2 erected on a base 3 via a dry bearing 20, and a cup that accommodates a torsion spring 7 in the axial direction inside. Part 18. The cup portion 18 extends to the bottom plate portion 13 of the base 3 and forms a housing that accommodates the torsion spring 7. An arm 19 that pivotally supports the pulley 6 is formed on the free end side of the cylindrical member 5.
[0021]
When the torsion spring 7 is compressed, one end 22 is brought into contact with the fixed surface 23 of the cylindrical member 5, and the other end 17 is engaged with the other end 16 of the friction member 9. Is housed inside. One end 22 of the torsion spring 7 may be fixed to the fixing surface 23.
[0022]
Next, a method for manufacturing the auto tensioner 1 in the above configuration will be described.
[0023]
First, the friction member 9 is installed on the base 3 of the base 3 so as to engage with the second step portion 12 formed on the base 3. Next, the torsion spring 7 is installed along the first step portion 11 so that the end portion engages with the other end 16 of the friction member 9. On the other hand, a dry bearing 20 is set on the inner periphery of the boss portion 4 of the cylindrical member 5. Then, the dry bearing 20 is inserted through the shaft 2 and fitted so as to cover the base 3 while twisting the cylindrical member 5. Thereby, the torsion spring 7 accommodated in the cylindrical member 5 is accommodated in a compressed state. Next, the collar 21 is fitted into the upper end of the shaft 2 and fixed by caulking.
[0024]
As a method other than the above, first, the dry bearing 20 is set on the cylindrical member 5, and the torsion spring 7 is accommodated inside the cylindrical member 5. Next, the friction member 9 is installed on the opening side of the cylindrical member 5. At this time, the friction member 9 is installed so that the other end 16 of the friction member 9 and the end of the torsion spring 7 are engaged with each other, and the one end 14 of the friction member 9 is in contact with the stopper means 15. Then, while twisting the cylindrical member 5, the dry bearing 20 can be inserted into the shaft 2 and fitted into the base 3, and the collar 21 can be fitted to the upper end of the shaft 2 and fixed by caulking.
[0025]
Next, the operation of the auto tensioner 1 manufactured as described above will be described.
[0026]
The auto tensioner 1 according to the present embodiment is used, for example, in an automobile engine belt system. In this case, the base 3 is fixed to the engine block or the like, and a transmission belt is stretched around the pulley 6.
[0027]
The auto tensioner 1 according to the present embodiment engages with the other end 17 of the torsion spring 7 when the cylindrical member 5 is rotated in a direction to spread the torsion spring 7 by the transmission power of the pulley 6. 2 is applied to the other end 16 of the friction member 9 by the torsional force of the torsion spring 7. At this time, since one end 14 of the friction member 9 is brought into contact with the stopper means 15 fixed to the base 3 and its movement is restrained, the friction member 9 is in contact with the inner peripheral surface 8 of the cylindrical member 5. It tries to spread with a force NF perpendicular to. As a result, a braking force is applied to the cylindrical member 5. Thus, when the cylindrical member 5 rotates, the braking force to the cylindrical member 5 is generated by the torsional force of the torsion spring 7 generated in conjunction with the rotation of the cylindrical member 5, and a damping effect is obtained. That is, as the torsional force from the torsion spring 7 increases, the braking force acting on the cylindrical member 5 increases and a high damping effect can be obtained. Further, since the friction member 9 is provided over substantially the entire circumference of the inner peripheral surface 8 of the cylindrical member 5, an excellent braking effect can be exhibited and a high damping effect can be obtained at any torsion angle. .
[0028]
In this way, the friction member 9 serving as a brake shoe is in surface contact with the inner peripheral surface 8 of the cylindrical member 5 and is in contact with the cylindrical member 5 as a whole, thereby suppressing uneven wear of the friction member 9. Is possible. Accordingly, a stable braking effect can be exhibited over a long period of time, and a high damping effect can be obtained.
[0029]
【The invention's effect】
The present invention is configured as described above. According to the invention of claim 1, when the cylindrical member is twisted in the direction in which the torsion spring expands, the torsional force is transmitted to one end of the friction member, and the friction member Since it tends to spread with respect to the inner periphery of the cylindrical member, the friction member is pressed in a wide range of the inner periphery of the cylindrical member. Therefore, the braking effect is good and an excellent damping effect can be obtained.
[0030]
According to the second aspect of the present invention, the friction member is disposed along most of the inner periphery of the cylindrical member, and the friction member is in a pressure contact state over a wide range of the inner periphery of the cylindrical member. For this reason, it is possible to suppress uneven wear of the friction member.
[0031]
According to the invention of claim 3, it is possible to easily dispose the friction member along the inner periphery of the cylindrical member.
[0032]
According to invention of Claim 4, the arrangement | positioning state along the cylindrical member inner periphery of a friction member is stabilized. Further, the contact area of the inner periphery of the cylindrical member of the friction member can be increased, and the braking effect can be ensured.
[0033]
According to the invention of claim 5, the friction member can be easily formed by integral molding.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of an embodiment of an auto tensioner according to the present invention.
2 is a cross-sectional view of the cylindrical member 5 in FIG. 1 as viewed from above.
FIG. 3 is a cross-sectional view showing a cross section taken along line AA in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Auto tensioner 2 Shaft 3 Base 4 Boss part 5 Cylindrical member 6 Pulley 7 Torsion spring 8 Inner peripheral surface 9 Friction member 10 Engagement part 17 End part

Claims (5)

A base on which a shaft is erected, a boss portion rotatably inserted into the shaft, a cylindrical member extending toward the base, and a pulley rotatably mounted at an eccentric position of the cylindrical member A torsion spring housed inside the cylindrical member in the axial direction and compressed in a state where one end is in contact with the cylindrical member, and one end is fixed to the base, and the inner circumference of the cylindrical member A curved arc-shaped friction member disposed along a surface, the bottom surface side of which is in contact with the bottom plate portion of the base, and the side surface side of which is in contact with the inner peripheral surface of the cylindrical member. The friction member is engaged with the other end of the friction member and the other end of the torsion spring, and the side surface of the friction member is brought into contact with the inner periphery of the cylindrical member in accordance with the torsional force of the torsion spring. Engagement part to spread in the direction The equipped auto tensioner, wherein the portions extending to the other end of the spring in the compressed state is pushed toward the friction member to the bottom plate portion.   The auto tensioner according to claim 1, wherein the friction member is disposed along 270 ° or more of an inner periphery of the cylindrical member.   The auto tensioner according to claim 2, wherein one end portion of the friction member is fixed to the base by being abutted against a stopper erected on the base.   The auto tensioner according to claim 3, wherein the friction member has an L-shaped cross section.   The auto-tensioner according to claim 3, wherein the friction member is formed of a synthetic resin of any one of polyamide, ultrahigh molecular weight polyethylene, and polytetrafluoroethylene.

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