JP3025167B2 - Belt 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 improvement in a belt tensioner mainly used for a belt drive mechanism of an automobile engine.

[0002]

2. Description of the Related Art A belt tensioner of this type is used for transmitting a driving force to a plurality of devices with a single belt to prevent slack of the belt and to surely transmit the driving force. This type of belt tensioner is disclosed, for example, in Japanese Patent Publication No. 62-2182.

The conventional belt tensioner disclosed in this publication is configured such that a tensioner arm is swingably mounted on a fixed portion provided on an engine block or the like, and a pulley is rotatably provided on this arm. . A torsion spring is mounted between the fixed portion and the tensioner arm, and biases the tensioner arm in a direction to tighten the belt.
Further, the torsion spring has a function of pressing a damping member provided on the tensioner arm side against a member on the fixed portion side, thereby generating a damping force for attenuating vibration when the tensioner arm swings. ing.

[0004]

However, the conventional belt tensioner described above has a function of rotating the tensioner arm by the torsion spring and a function of generating a damping force. There is a problem that the torque generated in the torsion spring changes depending on the moving position, and the damping force changes, and it is difficult to obtain a desired damping force.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a belt tensioner capable of generating a desired damping force regardless of the rotational position of a tensioner arm. With the goal.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a belt tensioner according to the present invention is provided with a fixed portion having a tensioner cup, and a swingable shaft provided on the fixed portion via a swing shaft. A tensioner arm, a pulley rotatably provided on the tensioner arm via a rotation axis parallel to the swing axis to receive the belt, a tensioner cup, and a tensioner arm interposed between the tensioner arm to tension the belt. First urging means for urging the tensioner arm, which is fixed to the tensioner arm and slidably contacts almost the entire outer peripheral surface of the tensioner cup, and generates friction with the tensioner cup when the tensioner arm swings. a ring-shaped damping band <br/>, fitted over substantially the entire circumference of the outer circumferential surface of the damping band, Dan Ngubando and at least one circular spring urging a substantially uniform and constant pressure to the tensioner cup side, of the damping band is divided in the circumferential direction
Divided member, and the divided member has flexibility.
It is characterized by being connected by a connection part .

The first biasing means is, for example, a coil spring housed in a tensioner cup and wound around a swing shaft. The damping member is, for example, a ring-shaped member provided on the outer peripheral surface of the tensioner cup. It is a dumping band.

The second biasing means is, for example, a circular spring that biases the outer periphery of the damping member from the outside to the inside over substantially the entire circumference thereof. Examples of the circular spring include a C-shaped spring, a band spring, and a coil spring. Can be

[0009]

According to the structure of the present invention described above, the rotation urging force for the tensioner arm is generated by the first urging means, and the damping force generated between the damping member and the tensioner cup of the fixed portion is equal to the second urging force. Generated by the biasing means. The urging force of these urging means can be set independently. The damping force is a friction force generated on a surface where the outer peripheral surface of the tensioner cup slides on the damping member.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a belt tensioner according to the present invention will be described below. The belt tensioner of the embodiment is
For example, it is used for a belt system of an automobile engine as shown in FIG. The belt system includes a drive pulley 1 attached to an output shaft of an engine, driven pulleys 2, 3, and 4 for an air conditioner, a power steering device, and an alternator, pulleys 5 and 6 for an idler, and a belt tensioner 10. And a single drive belt 7 is 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 urging means provided in the fixed portion 20, and the urging force causes the drive belt 7 to be taut. Further, when the drive belt 7 is mounted, the tensioner pulley 40 is mounted while being rotated to the position shown by the broken line in the figure.

Next, a schematic structure of the belt tensioner 10 of the embodiment will be described with reference to FIG.

The belt tensioner 10 has a tensioner cup 22 and a tensioner arm 30, and is attached to the fixed portion 20 (see FIG. 1) via the tensioner cup 22. The tensioner arm 30 can swing about the swing shaft (pivot bolt 23) with respect to the tensioner cup 22. The tensioner arm 30 has a cylindrical portion 30c, and the pivot bolt 23 is provided at the center of the cylindrical portion 30c. Tensioner pulley 40
Is rotatably provided on the tensioner arm 30 via a pulley bolt 41 which is a rotation axis parallel to the pivot bolt 23.

A damping band 32 is provided between the cylindrical portion 30c and the tensioner cup 22. The damping band 32 engages with the notch 30a of the cylindrical portion 30c so that the tensioner arm 30 is engaged.
Fixed to Three C-shaped springs 33 are provided on the outer peripheral surface of the damping band 32.

FIGS. 3 and 4 show the structure of the belt tensioner of the embodiment. FIG. 3 is a sectional view of the belt tensioner of FIG. 2, and FIG. 4 is an exploded view showing parts of the belt tensioner of FIG.

The tensioner cup 22 has a bolt engaging portion 22a that rises from the center of the bottom surface along the axial direction.
And a flange 22b formed on the outer periphery of the end. A torsion spring 50 is provided in the tensioner cup 22. A mounting hole 22c through which a bolt for mounting the tensioner cup 22 to the fixing part 20 (see FIG. 1) is formed is formed in the flange 22b, and a pivot bolt 23 is screwed into the bolt engaging part 22a.
The pivot bolt 23 has a stepped shape with a spline portion 23a formed at the tip. A pivot bushing 31 fixed to the tensioner arm 30 is attached to the pivot bolt 23. The axial movement of the pivot bushing 31 is regulated by the head of the pivot bolt, and the pivot bushing 31 is slidable in the rotational direction with a predetermined resistance. With such a configuration, the tensioner arm 30 can swing with respect to the fixed portion 20 (see FIG. 1).

The tensioner pulley 40 is rotatably attached to the tensioner arm 30 via a ball bearing 42 and a pulley bolt 41. Between the head of the pulley bolt 41 and the ball bearing 42,
A dust shield 43 for preventing the entry of dust is provided.

The torsion spring 50 has one end 51 fixed to the bottom surface of the tensioner cup 22 and the other end 5.
2 is fixed to the tensioner arm 30, and functions as a first urging means for urging the tensioner arm 30 in a direction to tension a drive belt (not shown) suspended on the tensioner pulley 40.

The cylindrical portion 30c of the tensioner arm 30 has three notches 30a formed at substantially equal intervals. The damping band 32 is fixed to the tensioner arm 30 by engaging the projection 32a with the notch 30a. The damping band 32 has a flange 32 k formed at an end thereof and a flange 22 k of the tensioner cup 22.
In a state in which the tensioner cup 22 is in contact with the outer peripheral surface of the tensioner cup 22, the outer peripheral surface of the tensioner cup 22 is slid over substantially the entire circumference.

Each of the three C-shaped springs 33 presses inward over substantially the entire outer peripheral surface of the damping band 32 and urges the damping band 32 toward the tensioner cup 22 with a substantially constant pressure.

As described above, the damping band 32 is in sliding contact with the outer peripheral surface of the tensioner cup 22 over substantially the entire inner peripheral surface thereof, and is brought into contact with the tensioner cup 22 when the tensioner arm 30 swings by the urging force of the C-shaped spring 33. It functions as a damping member that generates friction between them.

FIGS. 5 to 7 show the structure of the damping band 32. FIG. FIG. 5 shows a damping band 32 according to this embodiment.
6 and 7 are side views when the damping band of FIG. 5 is viewed from the directions of arrows VI and VII, respectively.

The damping band 32 is divided into three band pieces 32i (divided members) along the outer peripheral direction, and each band piece 32i is provided with a spring receiving portion 32g and a guide portion 32h.
And A C-shaped spring 3 is provided on the outer peripheral surface of the spring receiving portion 32g.
A circular spring such as 3 is fitted, and the guide portion 32h is located on the inner peripheral surface side of the cylindrical portion 30c of the tensioner arm 30.

An open portion 32b is formed between each of the band pieces 32i, and the open portion 32b is provided with a flexible U-shaped connecting portion 32j. Each band piece 32i is connected by a connecting portion 32j in a state where a predetermined gap D is formed. Each of the band pieces 32i is positioned by the connecting portion 32j, so that when the C-shaped spring 33 is attached to the damping band 32, the projecting portion 32a is easily inserted into the notch 30a of the tensioner arm 30 when the band piece 32i is assembled to the tensioner arm 30. Engages.

Each of the guides 32h has a projection 32a radially projecting outward from the outer peripheral surface. That is, three projections 32 a are formed on the damping band 32. The damping band 32 is fixed to the tensioner arm 30 by engaging each of the projections 32a with the notch 30a formed in the tensioner arm 30. On the lower edge of the spring receiving portion 32g,
A flange 32k is formed, and the flange 32k prevents the C-shaped spring 33 from being worn by contact with the tensioner cup 22.

The inner diameter of the C-shaped spring 33 at its natural length is smaller than the outer diameter when the damping band 32 is provided outside the tensioner cup 22. Therefore, when the C-shaped spring 33 is mounted on the outer peripheral surface of the damping band 32,
An urging force works inward due to the spring force of the spring.

Since the damping band 32 has a natural length at the opening 32b and is separated by the gap D, the C-shaped spring 33 is compressed by circumferentially compressing the connecting portion 32j in the manufacturing process or the like. The work of mounting on the outer peripheral surface becomes easy. The gap between the band pieces 32i absorbs thermal deformation of the damping band 32 after being assembled to the tensioner cup 22, and also functions as a drainage part for draining water that has entered the tensioner cup 22.

Although the present embodiment has shown the configuration in which the band pieces 32i are connected by the connection portions 32j, a configuration in which the connection portions 32j are not provided for the purpose of reducing manufacturing costs may be employed.

FIG. 8 is a plan view of a C-shaped spring 33 of a circular spring according to the present embodiment. Three C-shaped springs 33 are attached to the spring receiving portion 32g along the outer peripheral surface (see FIG. 3).

As the C-shaped spring 33, for example, a "retaining ring" used for fixing a ball bearing to an outer peripheral surface of a shaft can be used. The end 33a of the C-shaped spring 33 is formed with a hole 33b into which a jig used to bend the C-shaped spring 33 outward when assembled into the tensioner cup 22 can be engaged. The C-shaped spring 33 has a function of maintaining a circular shape even after being deformed and applying substantially uniform stress to each part. For this reason, the plate width b has a larger radial width as it is farther from the end.

The C-shaped spring 33 is fitted on the outer peripheral surface of the damping band 32 in a state where it is wider than a natural length. The inner peripheral surface of the C-shaped spring 33 is in close contact with the outer peripheral surface of the damping band 32 over substantially the entire periphery, and urges the outer peripheral surface of the damping band 32 inward. That is, the C-shaped spring 33 urges the damping band 32 to the tensioner cup 22 side with a substantially uniform and constant pressure over the entire circumference, so that the friction between the damping band 32 and the inner peripheral surface of the tensioner cup 22 is increased. A damping force is generated.

The damping band 32 is made of a polymer material such as nylon containing molybdenum in order to have self-lubricating property, in addition to polyacetal. Also,
Glass fiber reinforced nylon or carbon fiber reinforced plastic having excellent strength may be used.

In the belt tensioner of the embodiment configured as described above, the tensioner arm 30 is rotationally urged by the urging force of the torsion spring 50 to tension the drive belt 7, and the tensioner arm 30 is driven by the vibration of the drive belt. When swinging due to, for example, the C-shaped spring 33, the damping band 32 and the tensioner cup 22
The vibration is attenuated by the damping force generated between the two.

The damping force F is determined by the torsion spring 50
Generated by the action of the C-shaped spring 33 independent of
It is kept almost constant irrespective of the rotation angle of the tensioner arm 30. FIG. 9 shows the relationship between the torsion angle (rotation angle) θ of the tensioner arm and the damping force F generated by the friction between the damping band 32 and the tensioner cup 22. The solid line in the figure is the embodiment and the broken line is the conventional example. In the conventional example, the damping force F increases linearly as the torsion angle θ increases, but in the configuration of the embodiment, the damping force F is substantially constant regardless of the value of the torsion angle θ.

The damping force F needs to fall between the upper limit and the lower limit over the entire use angle range. Therefore, when the damping force F changes as in the conventional example, the allowable range of the spring torque with respect to the design value becomes small, and the upper limit is obtained even if the design value slightly deviates from the design target value.
Alternatively, there is a high possibility that the lower limit will be exceeded. On the other hand, when the damping force F is substantially constant as in the embodiment,
The allowable range of the spring torque with respect to the design value increases, and the damping force F can be kept between the upper limit and the lower limit even if the design value slightly deviates from the design target value.

In this embodiment, the C-shaped spring 33 is used.
The damping force generated by the torsion spring 50
Can be set independently of the rotating torque generated by the above, the respective values can be freely combined, and it is possible to easily respond to various requests.

Further, in this embodiment, the damping band 3
Since the frictional force acts on almost the entire circumference of the inner peripheral surface 2 and the outer peripheral surface of the tensioner cup 22, the frictional force is dispersed by a wide contact area, and a large damping force can be effectively applied without locally applying a strong force. And the durability of the damping band 32 and the like is improved. For example, a large damping force can be applied more effectively than that in which a part of the damping band 32 is pressed to apply the damping force F.

Further, since the damping band 32 is provided on the outer peripheral surface of the tensioner cup 22, there is no need to change the internal shape of the tensioner cup 22, and the manufacture is easy. Further, since the C-shaped spring 33 is provided along the damping band 32, it is not necessary to provide a dedicated installation place. Due to these synergistic effects, the belt tensioner can be easily provided without increasing the size.

The C-shaped spring 33 is provided with the damping band 3.
The C-shaped spring 33 can be easily attached because the gap D is formed in the damping band 32 in a natural length state. Also, by using a plurality of C-shaped springs 33,
A desired damping force can be easily obtained, and the damping force can be easily changed.

FIGS. 10 and 11 are test results showing the relationship between the torsion angle (rotation angle) θ of the tensioner arm, the damping force F generated by the friction between the damping band 32 and the tensioner cup 22, and the damping ratio.
Sample 1 shows a case using three C-shaped springs, sample 2 shows a case using four C-shaped springs, and sample 3 shows a case using five C-shaped springs. In FIG. 11, the solid line indicates sample 1, the broken line indicates sample 2, and the dashed line indicates sample 3. In these lines, the upper line shows the change in the load (forward load) when the rotation angle of the tensioner arm 30 is increased, and the lower line shows the change when the rotation angle of the tensioner arm 30 is decreased. Changes in load (reverse load) are shown. The damping force F in FIG. 10 is represented by the difference between the load average of the normal rotation load and the reverse rotation load and the reverse rotation load, and the damping ratio is indicated by the ratio of the load average and the damping ratio.

As shown in FIG. 10, in this embodiment, since the C-shaped spring 33 presses almost uniformly over almost the entire circumference, an effective damping force F can be applied.
A desired damping force F can be obtained without increasing the size of the device.

The damping force increases in the order of Sample 1, Sample 2, and Sample 3, and the damping force varies according to the number of C-shaped springs 33 to be mounted. Therefore, a desired damping force can be easily obtained.

Thus, in the present embodiment, virtually any required damping ratio can be realized, and it is possible to easily respond to various requests.

In the above embodiment, the end 3 of the C-shaped spring 33 is used.
Although the hole 33b is formed in the hole 3a, a configuration in which the hole 33b is not formed as shown in FIG.

Further, the second biasing means according to the present invention is not limited to the C-shaped spring 33 of the above embodiment, but may be, for example, an ordinary ring-shaped spring as shown in FIG. A circular spring such as a spring, a double spring, or a spring may be used. Further, the present invention is not limited to such a circular spring formed separately from the damping band 32, but may be formed integrally with the damping band 32, and the damping band 32 itself has a function of a second urging means. Is also good.

FIGS. 14 and 15 show the coil spring 36. FIG.
The coil spring 36 is formed by spirally winding a steel material of a round wire 36a having a predetermined length several times in the axial direction. Such a coil spring 36 is easy to manufacture, and the damping force can be easily changed by changing the length of the round wire 36a to be wound. In addition, since it is wound a plurality of times, attachment to the damping band 32 is easier than that of a single winding.

FIGS. 16 and 17 show a double ring 34.
The double ring 34 is formed by spirally winding a steel material having a uniform plate width b approximately twice in the axial direction. In the case where such a double ring 34 is used, since the plate width b and the plate thickness t are uniform, it is easier to manufacture as compared with the case where the C-shaped spring 33 is used, and a uniform contact surface is provided over the entire circumference. Easy to get. Further, similarly to the case of the coil spring 36, since the coil spring 36 is formed by winding a plurality of turns, it is easy to attach the coil spring 36 to the damping band 32.

FIGS. 18 and 19 show a mainspring type spring 35. The spring 35 is formed by spirally winding a steel material having a uniform plate width b in a circumferential direction. Even when the spring 35 is used, the double ring 3
It is clear that the same effect as in the case of using No. 4 can be obtained.

[0049]

As described above, according to the present invention, the rotation urging force for the tensioner arm generated by the first urging means and the rotation urging force between the damping member and the fixed portion by the second urging means are provided. The desired damping force can be obtained irrespective of the rotation angle of the tensioner arm, and the allowable range for the design value of the torque of the urging means can be increased. can do.

Further, since the frictional force acts substantially uniformly over substantially the entire outer peripheral surface of the tensioner cup, the damping force can be applied more effectively.

In addition, the combination of the rotational urging force and the damping force can be freely selected, and the damping force can be easily changed, so that various requirements can be easily met.

[Brief description of the drawings]

FIG. 1 is a front view showing a belt system of an automobile engine.

FIG. 2 is a side view showing the appearance of the belt tensioner according to the embodiment.

FIG. 3 is a sectional view of the belt tensioner of FIG. 2;

FIG. 4 is a component diagram of the belt tensioner of FIG. 2;

FIG. 5 is a front view of a damping band.

FIG. 6 is a side view of the damping band of FIG. 5 when viewed from the direction of arrow VI.

FIG. 7 is a side view of the damping band of FIG. 5 when viewed from the direction of arrow VII.

FIG. 8 is a front view of a C-shaped spring.

FIG. 9 is a graph showing a relationship between a torsion angle θ and a damping force F.

FIG. 10 is a diagram showing a test result of a damping force.

FIG. 11 is a graph showing a relationship between a torsion angle θ and a load.

FIG. 12 is a front view of a C-shaped spring.

FIG. 13 is a front view of a ring-shaped spring.

FIG. 14 is a front view of a spring.

FIG. 15 is a side view of the spring.

FIG. 16 is a front view of a double ring.

FIG. 17 is a side view of a double ring.

FIG. 18 is a front view of a mainspring spring.

FIG. 19 is a side view of a mainspring spring.

[Explanation of symbols]

 Reference Signs List 20 fixing part 21 mounting part 22 tensioner cup 23 pivot bolt 30 tensioner arm 30f notch 31 pivot bushing 32 damping band 32a projection 33 C-shaped spring 34 double ring 35 spring-type spring 36 coil spring 36 40 tensioner pulley 41 pulley bolt 50 screw

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

Claims (9)

(57) [Claims] A fixed portion provided with a tensioner cup; a tensioner arm swingably provided on the fixed portion via a swing shaft; and a tension shaft provided on the tensioner arm via a rotation shaft parallel to the swing shaft. A pulley provided rotatably and receiving the belt; a first urging means interposed between the tensioner cup and the tensioner arm for urging the tensioner arm in a direction to tension the belt; A ring-shaped damping bar fixed to the tensioner arm and slidably in contact with substantially the entire outer peripheral surface of the tensioner cup to generate friction with the tensioner cup when the tensioner arm swings;
And command, the fitted substantially over the entire circumference of the outer circumferential surface of the damping band, and at least one circular spring urging a substantially uniform and constant pressure the damping band on the tensioner cup side, the damping band Divided in the circumferential direction
Wherein the dividing member has flexibility
A belt tensioner characterized by being connected by: 2. The belt tensioner according to claim 1, wherein the first biasing means is a coil spring housed in the tensioner cup and wound around the swing shaft. 3. The belt tensioner according to claim 1, wherein at least three circular springs are provided. 4. The belt tensioner according to claim 1, wherein an inner diameter of the circular spring at a natural length is smaller than an outer diameter of the damping member provided outside the tensioner cup. 5. The belt tensioner according to claim 1, wherein the circular spring is a C-shaped spring having a C-shape and having a wider radial width at a portion farther from the end. 6. The belt tensioner according to claim 1, wherein the circular spring is a band-shaped spring formed by bending a band-shaped member into a C shape. 7. The belt tensioner according to claim 1, wherein the circular spring is a coil spring. 8. The belt tensioner according to claim 1, wherein the circular spring is a double ring formed by winding a linear member twice. 9. The steel in which the circular spring has a uniform plate width.
The belt tensioner according to claim 1, wherein the spring is a spiral spring formed by winding the material in a spiral shape in a circumferential direction .