JP3414524B2 - 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 of a belt tensioner mainly used for a belt driving mechanism of an automobile engine.

[0002]

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

In the conventional belt tensioner as disclosed in this publication, a tensioner arm is swingably attached to a fixed portion fixed to an engine block or the like, and a pulley is rotatably provided on this arm. . A torsion spring is attached between the fixed portion and the tensioner arm, and the torsion spring urges the tensioner arm in a direction to tension the belt.
In addition, the torsion spring has a function of pressing the damping member provided on the tensioner arm side against the member on the fixed portion side, thereby generating a damping force for damping the vibration when the tensioner arm swings. ing.

[0004]

However, in the conventional belt tensioner described above, the torsion spring has both the function of urging the tensioner arm to rotate and the function of generating the 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.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and provides a belt tensioner capable of generating a substantially constant damping force regardless of the rotational position of the tensioner arm. The purpose is to

[0006]

In order to achieve the above-mentioned object, 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 that is rotatably provided on the tensioner arm via a rotation axis parallel to the swing axis and receives the belt, and a tensioner that is interposed between the tensioner cup and the tensioner arm to tension the belt. First biasing means for biasing the arm and fixed to the tensioner arm ,
Sliding contact from inside over almost the entire circumference of the inner peripheral surface of the tensioner cup tensioner cup and the damping member to produce a friction between the tensioner cup during oscillation of the tensioner arm, a damping member with a substantially uniform and constant pressure over the entire circumference A second urging means for urging outward toward the side , and the damping member covers the opening of the tensioner cup over substantially the entire circumference and opens.
A ring-shaped damping band having a portion and a second
The urging means is a C-shaped spring having an open portion,
The position of the open part of the band and the position of the open part of the C-spring
Are coincident in the circumferential direction .

A first biasing means, for example, is accommodated in the tensioner cup, Ru coil springs der wound around the pivot shaft.

The damping band is, for example, a tensioner.
It is provided around the opening of the cup. Also a dumping van
Prevents the C-shaped spring from sliding in the circumferential direction near the open part
It is preferable that a stopper is provided.

[0009]

According to the above-described structure of the present invention, the rotational biasing force with respect to the tensioner arm is generated by the first biasing means, and the damping force generated between the damping member and the tensioner cup of the fixed portion is the second. It is generated by the biasing means. The urging force by these urging means can be set independently.

[0010]

Embodiments of the belt tensioner according to the present invention will be described below. The belt tensioner of the embodiment is
For example, it is used in a belt system of an automobile engine as shown in FIG. This 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, an alternator, idler pulleys 5 and 6, 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 with respect to the fixed portion 20 about a pivot bolt 23 which is a swing shaft. ing. The tensioner pulley 40 is biased upward in the drawing by a biasing means provided in the fixed portion 20, and the biasing force causes the drive belt 7 to be tensioned. Further, when the drive belt 7 is attached, the tensioner pulley 40 is attached in a state where the tensioner pulley 40 is 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 FIGS.

The fixed portion 20 includes a tensioner arm 30.
Is swingable, and tensioner pulley 4
0 is a pulley bolt 41 which is a rotary shaft parallel to the swing shaft.
It is rotatably provided on the tensioner arm 30 via. The fixing portion 20 is composed of a mounting portion 21 having mounting holes 21a formed at two locations, and a tensioner cup 22 having a torsion spring described later.

5 and 6 show the structure of the belt tensioner of the embodiment. A bolt engagement portion 22a rising toward the inside of the cup is formed in the center of the bottom surface of the tensioner cup 22 in which the torsion spring 50 is arranged. The pivot bolt 23, which is a swing shaft, is formed in the bolt engagement portion 22a. It is screwed.

The pivot bolt 23 has a threaded portion 23 at its tip.
It has a stepped shape in which a and the pilot portion 23b are formed. The outer diameter of the pilot portion 23b is the screw portion 23
It is between the peak diameter and the valley diameter of a.

A pivot bushing 31 fixed to a tensioner arm 30 is attached to the pivot bolt 23, and an upper O ring 24 and a lower O ring 25 are fixed above and below the pivot bushing 31. The O-rings 24 and 25 may be omitted.

Movement of the pivot bushing 31 in the axial direction is restricted by the head of the pivot bolt, and the pivot bushing 31 is slidable in the rotation direction with a predetermined resistance. As a result, the tensioner arm 30 can swing with respect to the fixed portion 20.

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 in which a drive belt (not shown) suspended on the tensioner pulley 40 is tensioned.

The tensioner pulley 40 is rotatably attached to the tensioner arm 30 by a pulley bolt 41 via a ball bearing 42. A dust shield 43 that prevents dust from entering is provided between the head of the pulley bolt 41 and the ball bearing 42.

FIG. 6 is a plan view of the tensioner arm 30 of the belt tensioner of FIG. 5 as seen from below along the line VI-VI of FIG. A ring-shaped damping band 32 is attached to the tensioner arm 30 so as to extend along the inner circumferential surface of the tensioner cup 22 over the entire circumference.

7 and 8 show the structure of the damping band 32. The damping band 32 is the damping band 3
The protrusion 32a protruding inward from the upper surface of 2 is fixed to the tensioner arm 30 by engaging with the recess 30a provided in the tensioner arm 30 (FIG. 6).
reference). The protrusion 32a is formed with a notch 32f for easy mounting.

The damping band 32 is in sliding contact with the inner peripheral surface of the tensioner cup 22 over almost the entire outer peripheral surface thereof, and functions as a damping member that causes friction with the tensioner cup 22 when the tensioner arm 30 swings. To do.

On the outer peripheral surface of the damping band 32, a grease reservoir groove 32b is formed along the circumferential direction. The groove 32b of the grease reservoir is formed along the circumferential direction because it causes damage due to fatigue when formed in the axial direction. In addition, although the number of grooves is single in the embodiment, a plurality of grooves may be formed or may not be formed.

Further, the damping band 32 has the protrusion 3
It is open on the side facing 2a, and this open portion 32c
Absorbs the thermal deformation of the damping band 32, and
It functions as a water draining portion for draining water that has entered the tensioner cup 22.

A supporting portion 32d is formed on the inner peripheral surface of the damping band 32 along the circumferential direction, and the supporting portion 32d is formed.
Supports a C-shaped spring 33 described later. Support part 32d
A stopper 32e is projectingly provided near the open portion 32c at the end of the stopper 32e. The stopper 32e prevents the C-shaped spring 33 from sliding in the circumferential direction.

FIG. 9 is a plan view of the C-shaped spring 33 according to this embodiment. The C-shaped spring 33 is a ring-shaped spring and functions as a second urging unit that urges the damping member toward the tensioner cup 22 side with a substantially uniform and constant pressure over the entire circumference. As the C-shaped spring 33, for example, a "retaining ring" used for fixing a ball bearing in a pipe can be used. That is, the C-shaped spring 33 has about 3
It is formed in a C-shape extending over an angle range of 30 degrees and is open at the end 33a. The end portion 33a has a hole 3 into which a jig used for bending the C-shaped spring 33 inward when engaged in the tensioner cup 22 can be engaged.
3b is formed. The C-shaped spring 33 retains a circular shape even after being deformed, and has a function of applying a substantially uniform stress to each part. Therefore, the plate width b is gradually increased from the end. The characteristics of such a retaining ring are conventionally known and will not be described here.

As shown in FIG. 10, the C-shaped spring 33 is fitted inside the damping band 32 in a compressed state, and is sandwiched between the upper surface of the support portion 32d and the lower surface of the tensioner arm 30 as shown in FIG. It The outer peripheral surface of the C-shaped spring 33 is in close contact with the inner peripheral surface of the damping band 32 over substantially the entire circumference, and urges the inner peripheral surface of the damping band 32 outward. That is, the C-shaped spring 33 urges the damping band 32 toward the tensioner cup 22 side with a substantially uniform and constant pressure over the entire circumference, whereby friction between the damping band 32 and the inner peripheral surface of the tensioner cup 22 is caused. 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 constructed as described above, the tensioner arm 30 is rotationally biased by the biasing force of the torsion spring 50 to tension the drive belt 7, and the tensioner arm 30 vibrates the drive belt. When swinging by, for example, the vibration is damped by the damping force generated between the damping band 32 and the tensioner cup 22 by the C-shaped spring 33.

Since the damping force is generated by the C-shaped spring 33 independent of the torsion spring 50, the damping force is kept substantially constant regardless of the rotation angle of the tensioner arm 30. FIG. 11 shows the torsion angle (rotation angle) θ of the tensioner arm, the damping band 32, and the tensioner cup 2.
2 shows the relationship with the damping force F generated by friction with 2. 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 also increases as a linear function as the torsion angle θ increases, but in the configuration of the embodiment, the damping force F becomes 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 operating 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 even if the design value slightly deviates from the design target value, the upper limit,
Or there is a high possibility of exceeding the lower limit. On the other hand, when the damping force F is almost constant as in the embodiment,
The allowable range of the torque of the spring with respect to the design value becomes large, and the damping force F can be kept between the upper limit and the lower limit even if the design value deviates slightly from the design target value.

In the case of this embodiment, the C-shaped spring 33 is used.
The damping force generated by the torsion spring 50
Since it can be set independently of the turning torque generated by, the respective values can be freely combined, and it is possible to easily meet more diverse requirements.

Further, in the C-shaped spring 33 of this embodiment, since the frictional force acts substantially uniformly over the entire circumference, a strong force does not act locally, and for example, the damping band 3 is used.
The damping force F can be more effectively applied as compared with the case where a part of 2 is pressed to apply the damping force F. Further, since the C-shaped spring 33 is provided along the damping band 32, it is not necessary to provide a dedicated installation place, and due to the synergistic effect of these, the belt tensioner can be easily provided without increasing its size. Further, since the frictional force acts almost uniformly over the entire circumference, a strong force does not act locally, and the durability of the damping band 32 and the like is improved.

The C-shaped spring 33 is used for the damping band 3
It can be easily manufactured and replaced because it can be attached by simply fitting it in 2.

12 and 13 are test results showing the relationship between the torsion angle (rotation angle) θ of the tensioner arm and the damping force F and the damping rate generated by the friction between the damping band 32 and the tensioner cup 22.
Sample 1 is a C-shaped spring with a relatively small spring force,
Sample 2 shows a case where a C-shaped spring having a relatively large spring force is used. In FIG. 13, the solid line indicates Sample 1 and the broken line indicates Sample 2. Further, in the solid line and the broken line, the upper line shows the change of the load (normal rotation load) when the rotation angle of the tensioner arm 30 is increased, and the lower line shows the change of the rotation angle of the tensioner arm 30. The change in load (reverse load) is shown. The damping force F in FIG. 12 is indicated by the difference between the load average of the forward rotation load and the reverse rotation load, and the reverse rotation load, and the damping rate is indicated by the ratio of the load average and the damping rate.

As shown in FIG. 12, in Sample 2, 5
A damping force F of 5.1 kg is acting. For example, by pressing only a part of the damping band 32, the damping force F
In order to apply such a large damping force, a fairly large spring is required,
The device body had to be upsized. On the other hand, in the present embodiment, since the C-shaped spring 33 is pressed almost uniformly over the entire circumference, an effective damping force F can be applied, and large damping can be achieved without increasing the size of the device. The force F can be obtained.

As described above, in the present embodiment, virtually all required damping rates can be realized, and more diverse requirements can be easily met.

In the above embodiment, the end 3 of the C-shaped spring 33 is
Although the hole 33b is formed in 3a, the hole 33b may not be formed as shown in FIG. 14 for the purpose of reducing the manufacturing cost.

The second urging means according to the present invention is not limited to the C-shaped spring 33 of the above-mentioned embodiment, but may be a normal ring-shaped spring as shown in FIG. You may apply a double spring, a spring type spring, etc.
Further, the present invention is not limited to such a ring-shaped spring formed separately from the damping band 32, but is integrally formed with the damping band 32, and the damping band 32 itself has the function of the second urging means. May be.

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 in the axial direction about twice. In the case where such a double ring 34 is used, the stopper 32e in the above embodiment is unnecessary. When such a double ring 34 is used, since the plate width b and the plate thickness t are uniform, the manufacturing is easier than that using the C-shaped spring 33, and a uniform contact surface is easily obtained over the entire circumference. . Moreover, since it is wound a plurality of times, the mounting becomes easy.

18 and 19 show a mainspring spring 35. The mainspring spring 35 is formed by spirally winding a steel material having a uniform plate width b in the 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 4 can be obtained.

[0042]

As described above, according to the present invention, the turning biasing force generated by the first biasing means with respect to the tensioner arm and the damping force between the damping member and the fixed portion are secured by the second biasing means. Since the damping force acting on the can be set independently and independently, the damping force can be kept almost constant regardless of the rotation angle of the tensioner arm, and the allowable value of the torque of the biasing means against the design value The width can be increased.

Since the combination of the rotational urging force and the damping force can be freely selected, it is possible to easily meet various demands.

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

[Brief description of drawings]

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

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

FIG. 3 is a side view showing an appearance of a belt tensioner according to this embodiment.

FIG. 4 is a front view showing the appearance of a belt tensioner according to this embodiment.

5 is a cross-sectional view of the belt tensioner of FIG. 2 taken along the line VV.

6 is a plan view of the tensioner arm of FIG. 5 as seen from below along line VI-VI.

FIG. 7 is a front view of a damping band.

8 is a sectional view taken along line VIII-VIII of the damping band of FIG.

FIG. 9 is a front view of a C-shaped spring.

FIG. 10 is a partial perspective view of a damping band and a C-shaped spring.

FIG. 11 is a graph showing a relationship between a torsion angle θ and a damping force F.

FIG. 12 is a diagram showing a test result of damping force.

FIG. 13 is a graph showing the relationship between the twist angle θ and the load.

FIG. 14 is a front view of a C-shaped spring.

FIG. 15 is a front view of a ring-shaped 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 the mainspring.

FIG. 19 is a side view of the mainspring.

[Explanation of symbols]

20 Fixed part 21 Attachment 22 Tensioner cup 23 Pivot bolt 30 Tensioner arm 31 Pivot bushing 32 damping band 32a protrusion 32b groove 33 C type spring 34 double ring 35 Mainspring 36 ring-shaped spring 40 Tensioner pulley 41 pulley bolt 50 torsion spring

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H ^7/ 00-7/24 F02B 67/06

Claims (4)

(57) [Claims] 1. A fixed part having a tensioner cup, a tensioner arm swingably provided on the fixed part via a swing shaft, and a tensioner arm provided on the tensioner arm via a rotary shaft parallel to the swing shaft. A pulley that is rotatably provided to receive the belt, and a first biasing unit that is interposed between the tensioner cup and the tensioner arm and biases the tensioner arm in a direction to tension the belt. A damping member that is fixed to the tensioner arm, is in sliding contact with the inner circumferential surface of the tensioner cup from substantially the entire circumference, and causes friction with the tensioner cup when the tensioner arm swings, and the damping member. said toward the tensioner cup side with a substantially uniform and constant pressure over the entire circumference with outwardly To the second and a biasing means, said damping member having a flange and an open portion which covers over substantially the whole circumference of the opening portion of the tensioner cup
Is a ring-shaped damping band, the second biasing means is a C-shaped spring having an opening, and the position of the opening of the damping band and the C-shaped spring
A belt tensioner characterized in that the position of the open portion of the belt tensioner matches in the circumferential direction . 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 damping band comprises the tensioner.
Contractor characterized in that it is provided around the opening of the ner cup
The belt tensioner according to claim 1. 4. Near the opening of the damping band
Is a stopper that prevents the C-shaped spring from sliding in the circumferential direction.
The belt teeter according to claim 1, which is provided.
Conditioner.