JPH08270742A - Belt tensioner - Google Patents

Abstract

PURPOSE: To generate approximately constant damping force without respect to a rotational position of a tensioner arm, and to prevent damage in a damping member due to rotational energizing force by the tensioner arm. CONSTITUTION: An oscillational tensioner arm 30 is arranged in a fixing part provided with a tensioner cup 22 via an oscillation shaft. A pulley 40 is arranged in the tensioner arm 30 rotationally so as to receive a belt. A damping band 32 is fixed in the tensioner arm 30 so as to be brought into slide contact with an approximately overall circumference in an opening circumference edge of the tensioner cup 22 from the inside, and friction is generated between the tensioner cup 22 and the damping band 32 when the tensioner arm 30 is oscillated. A C-shaped spring 33 energizes the damping band 32 to the tensioner cup 22 side. In the damping band 32, projection parts 32a fixed in the rotational direction by means of the tensioner arm 30 are arranged in three positions.

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. In this type of belt tensioner, a tensioner arm is swingably attached to a fixed part fixed to an engine block, etc., and a pulley is rotatably provided on this arm, and a coil spring is provided between the fixed part and the tensioner arm. There is one that is attached. The coil spring urges the tensioner arm in a direction to tension the belt. In addition, a damping member is provided around the opening of the tensioner cup to generate friction between the tensioner arm and the tensioner cup when the tensioner arm swings, thereby damping the vibration when the tensioner arm swings. Occurs.

[0003]

However, in the above-mentioned conventional belt tensioner, the coil 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 coil spring changes depending on the moving position, and the damping force changes. Further, when a rotational biasing force larger than that of the tensioner arm acts, the damping member fixed to the tensioner arm may be damaged.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and generates a substantially constant damping force regardless of the rotational position of the tensioner arm, and also provides the rotation of the tensioner arm. An object of the present invention is to provide a belt tensioner in which a damping member is less likely to be damaged by a force.

[0005]

In order to solve the above-mentioned problems, a belt tensioner according to the present invention has a fixed portion having a tensioner cup and a tensioner provided on the fixed portion so as to be swingable via a swing shaft. An arm, a pulley that is rotatably provided on the tensioner arm via a rotation axis that is parallel to the swing axis, and receives the belt, and a tensioner arm that is wound around the swing axis and biases the tensioner arm in a direction to tension the belt. Of the coil spring and the damping member that makes sliding contact with the entire circumference of the opening edge of the tensioner cup from the inside, and causes friction between the tensioner cup and the tensioner cup when the tensioner arm swings, and urges the damping member toward the tensioner cup side. And a damping member for fixing the damping member to the tensioner arm in a rotational direction. It is characterized by having a turn stop portion of at least two or more positions.

The biasing means is, for example, a C-shaped spring, a ring-shaped spring, a ring-shaped spring such as a double ring.

[0007]

According to the above-described structure of the present invention, the rotational urging force with respect to the tensioner arm is generated by the coil spring, and the damping force generated between the damping member and the tensioner cup of the fixed portion is urged by the C-shaped spring or the like. It is generated by means. These biasing forces can be set independently.

[0008]

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 in which mounting holes 21a are formed at two locations, and a tensioner cup 22 in which a coil spring described later is arranged.

FIG. 5 shows the structure of the belt tensioner of this embodiment, and FIG. 6 is a sectional view of the tensioner arm 30 of the belt tensioner of FIG. 5 as seen from below along the line VI-VI of FIG. Is.

At the center of the bottom surface of the tensioner cup 22 in which the coil spring 50 is disposed, a bolt engaging portion 22a that rises toward the inside of the cup is formed. The bolt engaging portion 22a has a pivot which is a swing shaft. The bolt 23 is screwed. The pivot bolt 23 has a threaded portion 2 at the tip.
It has a stepped shape in which 3a and a pilot portion 23b are formed.

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, respectively. The upper O-ring 24 and the lower O-ring 25 may be omitted.

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

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. 7 is a front view of the coil spring 50. The coil spring 50 is a coil-shaped torsion spring as shown in FIG. 7, and is formed by spirally winding a metal wire 53 having a circular cross section.

The coil spring 50 has one end 51.
(See FIG. 5) is fitted and locked in a recess (not shown) formed in the vicinity of the tensioner cup 22 and fixed to the tensioner cup 22, and as shown in FIG.
Is locked to the first protrusion 22b protruding from the bottom surface of the tensioner arm 30, and the metal wire 53 is connected to the second protrusion 22c.
And is fixed to the tensioner arm 30. The coil spring 50 is properly twisted and is fixed to the fixing portion 20.
The tensioner arm 30 is interposed between the tensioner arm 30 and the tensioner arm 30 in a compressed state. In this state, the tensioner arm 30 is urged in the rotational direction in a direction in which the drive belt suspended by the tensioner pulley 40 is tensioned.

The coil spring 50 is formed in a conical shape that narrows as it approaches the periphery of the opening.
It extends upward in the figure at an inclination angle of about 2 degrees. On the other hand, the tensioner cup 22 is formed in a substantially cylindrical shape, and therefore the coil spring 50 is housed in the tensioner cup 22 in a state of being separated from the damping band 32 near the opening where the damping band 32 is provided. This allows a space in the vicinity of the opening periphery without increasing the size of the device itself, and when the damping band 32 is press-fitted into the opening periphery of the tensioner cup 22 at the time of assembly or the like, the damping band 3
Since 2 does not contact the tensioner arm 30, the assembling work becomes easy.

Usually, the rotational biasing force of the coil spring 50 largely depends on the entire length of the metal wire 53. In this embodiment, the coil spring 50 has a conical shape, and the outer diameter in the axial direction of the damping band 32 is reduced in the vicinity of the opening edge of the tensioner cup 22 in which the damping band 32 is provided, while the vicinity of the bottom surface with a relatively large space Then, by increasing the outer diameter, the coil spring 50
Since the predetermined length of the entire metal wire 53 can be secured, the biasing force of the tensioner arm 30 by the coil spring 50 is not impaired, and the apparatus itself can be made compact.

FIG. 8A shows a conventional coil spring 5
0a shows the structure, and (b) shows the structure of the coil spring 50 of this embodiment. When the coil spring 50a has the same outer diameter in the axial direction as shown in (a), the metal wires 53 that are vertically adjacent to each other when the rotational biasing force or the like acts.
The a comes into contact with each other, causing adverse effects such as wear and noise of the metal wire 53a. By forming the coil spring 50 into a conical shape as in the present embodiment, a gap between the adjacent metal wires 53 in the vertical direction can be secured, and the above-mentioned adverse effects due to the contact between the wires can be reduced.

9 and 10 show the structure of the damping band 32. The damping band 32 is in sliding contact with the inner peripheral surface of the tensioner cup 22 over substantially 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.

In the damping band 32, the three protrusions 32a projecting inward from the vicinity of the peripheral edge of the opening are engaged with the recesses 30a (see FIG. 6) formed in the tensioner arm 30, respectively. It is fixed to. Thus these protrusions 32
A functions as a detent portion that fixes the damping band 32 to the tensioner arm 30 in the rotation direction. Further, since the plurality of protrusions 32a are provided, the rotational biasing force of the tensioner arm 30 is dispersed, and problems such as breakage of the protrusions 32a hardly occur.

Between each projection 32a of the damping band 32, an opening 32c extending axially and a slit 32g are provided.
Is formed. These open parts 32c and slits 32g
Is a damping band 3 at the time of thermal deformation and assembly.
It functions as a drainage part for absorbing the deformation and flexure of No. 2 and draining the water that has entered the tensioner cup 22.

FIG. 11 is a plan view of the C-shaped spring 33 according to this embodiment. The C-shaped spring 33 is a ring-shaped spring,
The damping member is urged toward the tensioner cup 22 side with a substantially uniform and constant pressure over the entire circumference. C-shaped spring 33
Can utilize, for example, a "retaining ring" used to secure a ball bearing in a pipe. That is, the C-shaped spring 33 is formed in a C-shape extending over an angular range of about 330 degrees, and is open at the end 33a. The end portion 33a is formed with a hole 33b into which a jig used to bend the C-shaped spring 33 inward when engaged in the tensioner cup 22 can be engaged. The C-shaped spring 33 is formed such that the plate width b gradually increases from the end, maintains a circular shape even after deformation, and substantially uniform stress acts on each part. The characteristics of such a retaining ring are conventionally known and will not be described here.

FIG. 12 shows a damping band 32 and C.
It is a partial perspective view of the die spring 33. Damping band 32
A plurality of supporting portions 32d are formed on the inner peripheral surface of the above along the circumferential direction, and the supporting portions 32d support the C-shaped spring 33 from above and below. A stopper 32e is provided at the end of the support portion 32d near the opening 32c so as to prevent the C-shaped spring 33 from sliding in the circumferential direction.

The C-shaped spring 33 is fitted inside the damping band 32 in a compressed state, and is clamped by the support portion 32d. 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. Damping band 3
A plurality of grease reservoir grooves may be formed along the circumferential direction on the outer peripheral surface of 2.

In the belt tensioner of the present embodiment constructed as described above, the tensioner arm 30 is rotationally biased by the biasing force of the coil spring 50, and the drive belt 7 is driven.
When the tensioner arm 30 swings due to vibration of the drive belt and the like, the vibration is damped by the damping force (friction force) generated between the damping band 32 and the tensioner cup 22 by the C-shaped spring 33. Let Since the damping force is generated by the C-shaped spring 33 independent of the coil spring 50, it is kept constant regardless of the rotation angle of the tensioner arm 30.

Further, since the damping force generated by the C-shaped spring 33 can be set independently of the turning torque generated by the coil spring 50, the respective values can be freely combined and a wider variety of values can be obtained. You can easily respond to requests.

Further, since the damping band 32 is fixed to the tensioner arm 30 via the plurality of protrusions 32a, the rotational biasing force of the tensioner arm 30 is dispersed to the plurality of protrusions 32a. Therefore, the protrusion 32a, and hence the damping band 32, is unlikely to be damaged.

Further, by making the coil spring 50 into a conical shape, the damping band 32 and the tensioner arm 30 are separated from each other, and a space can be provided in the peripheral edge of the opening, so that the apparatus itself can be formed compact and
When the damping band 32 is pressed into the opening peripheral edge of the tensioner cup 22 during assembly or the like, the damping band 32 does not come into contact with the tensioner arm 30 and the assembly work is facilitated.

The thickness, material and shape of the metal wire are appropriately selected according to the required rotational urging force and damping force. For example, the cross-sectional shape of the metal wire may be a rectangle, an ellipse, or a combination thereof.

13 and 14 show another example of the damping band 32 used in the present invention. The damping band 32 has two opening portions 32c facing each other, and two damping band pieces 32 are formed by these opening portions 32c.
It is divided into i. A U-shaped joint 32k is provided in one opening 32c, and two damping band pieces 32i are connected by this. By connecting the damping band pieces 32i with the joint 32k in this manner, each damping band piece 32i is positioned at a predetermined position, and work such as assembling becomes easy.

The rotation stopping portion 32h is provided at one end of each damping band piece 32i, and fixes the damping band 32 to the tensioner arm 30 in the rotational direction, like the protrusion 32a of the above embodiment. The rotation stopping portion 32h is
It protrudes inward from the vicinity of the peripheral edge of the opening, and a detent hole 32j is formed inside thereof. This stop hole 32j
Then, a detent pin (not shown) formed on the tensioner arm 30 is engaged, and the damping band 32 is fixed to the tensioner arm 30 in the rotational direction. Further, a cutout 32f is formed in the rotation stopping portion 32h, so that the deformation of the damping band 32 during assembly or the like is absorbed, and the tensioner arm 30 can be easily attached. Further, similarly to the damping band 32 of the above-described embodiment, the support portion 32d is provided along the circumferential direction to support the ring-shaped spring.

When such a damping band 32 is used, the tensioner arms 3 are provided at the two detent portions 32h.
The rotational urging force of 0 is dispersed, and the detent portion 32h and eventually the damping band 32 are less likely to be damaged.

[0037]

As described above, according to the present invention, a substantially constant damping force is generated regardless of the rotating position of the tensioner arm, and the damping member is not damaged by the rotational biasing force of the tensioner arm. A belt tensioner that hardly occurs can be obtained.

[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 sectional view taken along line VV of the belt tensioner of FIG.

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

FIG. 7 is a front view of a coil spring used in the embodiment.

FIG. 8A is a partial cross-sectional view of a coil spring of a conventional example and FIG.

FIG. 9 is a front view of a damping band used in this embodiment.

10 is a cross-sectional view of the damping band of FIG. 9 taken along the line XX.

FIG. 11 is a front view of a C-shaped spring used in the embodiment.

FIG. 12 is a partial perspective view of a damping band and a C-shaped spring.

FIG. 13 is a front view of another example of the damping band.

FIG. 14 is a diagram of the damping band of FIG. 13 viewed from the direction of arrow XIV.

[Explanation of symbols]

 20 Fixed Part 21 Attachment Part 22 Tensioner Cup 23 Pivot Bolt 30 Tensioner Arm 31 Pivot Bushing 32 Damping Band 32a Protrusion 33 C-Shaped Spring 40 Tensioner Pulley 41 Pulley Bolt 50 Coil Spring 53 Metal Wire

Claims (7)

[Claims] 1. A fixing portion having a tensioner cup,
A tensioner arm rotatably provided on the fixed portion via a swing shaft; a pulley rotatably provided on the tensioner arm via a rotation shaft parallel to the swing shaft to receive a belt; A coil spring, which is wound around a swing shaft and biases the tensioner arm in a direction of tensioning the belt, is in sliding contact with the coil spring from the inside over substantially the entire circumference of the opening of the tensioner cup, and the tensioner arm swings. A damping member that sometimes causes friction with the tensioner cup and a biasing unit that biases the damping member toward the tensioner cup side are provided, and the damping member causes the damping member to rotate in the rotation direction of the tensioner arm. A belt tensioner having at least two fixing portions for fixing. 2. The belt according to claim 1, wherein the detent portion is a protrusion portion that protrudes inward from the vicinity of the opening portion of the damping member and engages with a recess formed in the tensioner arm. Tensioner. 3. The belt tensioner according to claim 1, wherein the detent portion has an engagement hole into which an engagement pin provided in the tensioner arm is inserted. 4. The belt tensioner according to claim 1, wherein the damping member has an opening that absorbs deformation. 5. The belt tensioner according to claim 1, wherein the coil spring is a coil spring wound in a coil shape. 6. The urging means is a ring-shaped spring for urging the damping member toward the tensioner cup side with a substantially uniform and constant pressure.
Belt tensioner described in. 7. The belt tensioner according to claim 1, wherein the coil spring is formed in a conical shape, and is housed in the tensioner cup in a state of being separated from the damping member.