JP2002130402A - Automatic tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sufficiently durable automatic tensioner enhancing the rigidity and smoothing the operation of a support portion of an arm and capable of suppressing rattling of the arm relative to a support shaft and its unreasonable inclination due to the increase in the rattling. SOLUTION: This automatic tensioner is provided with the fixing support shaft 1, the arm 2 elastically energized in a rotating direction with its one end side rotatably and externally fitted and supported to the support shaft 1, and a tension pulley 3 rotatably supported to the other end side of the arm 2. The arm 2 is supported to the support shaft 1 via a radial type roller bearing 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto-tensioner for automatically maintaining an appropriate tension in a belt of a belt transmission device used as a power transmission means in a vehicle or the like. An arm having one end elastically urged in one rotation direction with the one end being rotatably fitted to the support shaft and a tension pulley rotatably supported by the other end of the arm; Regarding tensioner.

[0002]

2. Description of the Related Art Conventionally, in an auto tensioner of this type, as shown in FIG.
Had been fitted through.

[0003]

The bush 50 may be formed of a material having excellent wear resistance and low friction characteristics. However, since the bush 50 is made of a resin material, the bush 50 may be damaged by an overload. It can be said that the nature is insufficient. In particular,
In an auto-tensioner of the type in which the tension pulley 3 is offset, a belt load acting on the tension pulley 3 causes the arm 2 to rotate around the center O of the shaft support portion of the arm 2.
A moment М acts to rotate the arm 2 on the side where the tip approaches the axis P. Therefore, conventionally,
As illustrated in FIG. 4, forces F, F that press the support shaft 1 against the ends 51, 51 of the bush 50 at a position where the base end of the arm 2 is fitted to the support shaft by the moment М. Act in a concentrated manner, so that the bush 50 tends to wear to one end, that is, to easily wear unevenly. Due to the uneven wear of the bush 50, rattling may occur between the base end of the arm 2 and the support shaft, and the rattling may become severe, and the arm 2 may be unduly tilted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to increase rigidity and smooth operation of a support portion of an arm, and to make the arm rattle with respect to a support shaft. Therefore, an object of the present invention is to provide an auto-tensioner having sufficient durability, which can suppress the arm from being unduly tilted due to increase in the armature.

[0005]

According to a first aspect of the present invention, there is provided an auto-tensioner which is resilient in one rotation direction with a fixed support shaft and one end side rotatably fitted to the support shaft. In an auto-tensioner having an arm to be urged and a tension pulley rotatably supported on the other end of the arm, the arm is supported via a radial type roller bearing with respect to the support shaft. Is a characteristic configuration.

According to the configuration of the first aspect of the present invention, the arm is configured to be rolled and supported on the support shaft via a roller bearing having a high load-loading capability and a small radial dimension. The rigidity and the smooth operation of the support portion between the shaft and the support shaft can be improved, and the followability due to the fluctuation of the tension is improved.

As a comparative example, a double row ball bearing may be interposed between the base end of the arm and the support shaft. In this case, the ball of the ball bearing is moved in the axial direction by the moment of the arm. Since the force to move the ball acts, the ball may come into strong contact with the inner and outer rings of the bearing, the retainer, etc., thereby increasing the friction of the ball and increasing the rotation of the arm. However, since the roller bearing roller has a structure that is easily moved in the axial direction as in the present invention, the rotation of the roller does not become unduly heavy, and the smooth rotation of the arm is maintained.

According to a second aspect of the present invention, there is provided an auto tensioner according to the first aspect, wherein the tension pulley is offset from the support shaft in an axial direction. I do.

According to the configuration of the second aspect of the present invention, even in an auto tensioner having an offset structure in which a high load is applied to the arm supporting portion, the arm supporting rigidity is improved, and the height of the auto tensioner is increased. This is advantageous in durability and smooth operation.

According to a third aspect of the present invention, in the auto-tensioner according to the first or second aspect, the roller bearing has a shell-type outer ring and a plurality of rollers, and an inner ring of the roller group. An outer peripheral surface of the spindle is used as a track.

According to the third aspect of the present invention, the roller bearing has a shell-type outer ring and a plurality of rollers, and the outer peripheral surface of the support shaft is used as an inner ring race of the roller group. Therefore, the width of this bearing in the radial direction is small, and it has dimensional compatibility with the conventional resin bush. It is possible to avoid a large dimensional change in the design of the fitting portion and a change in the processing step.

An auto-tensioner according to a fourth aspect of the present invention is characterized in that seals are attached to both axial ends of an outer ring of the roller bearing.

According to the fourth aspect of the present invention, the seal can sufficiently prevent foreign matters such as abrasion powder and moisture of the friction plate from entering the bearing, and the seal is particularly built in the outer ring. By doing so, workability can be improved as compared with the case where the seal is separately assembled.

According to a fifth aspect of the present invention, in the auto-tensioner according to the third or fourth aspect, the support shaft is made of a metal material, and the outer peripheral surface thereof is formed as an inner ring raceway of the roller group. The region is hardened.

According to the configuration of the fifth aspect of the present invention, the area of the roller group on the outer peripheral surface of the roller group, which is the inner ring raceway, is hardened even if the roller group is brought into contact with the roller group. Since it is possible to sufficiently exhibit abrasion resistance against rolling, high durability and smooth operation can be further improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a developed sectional view showing an example of an auto tensioner according to the present invention. In the drawing, A indicates the entire auto tensioner, 1 is a fixed case having a support shaft 11, 2 is an arm, 3 is a tension pulley, 4 is a torsion coil spring, 5 is a friction plate, 6 is a friction plate holding plate, Reference numeral 7 denotes a radial-type needle roller bearing. Also, B
Is a belt wound around the outer periphery of the tension pulley 3.

This auto-tensioner A is provided at the other end of the arm 2 with respect to the center O1 in the axial center of the base end (having a boss 21 described later) as one end of the arm 2 with respect to the support shaft 11. The structure has a structure in which the axial center O2 of the shaft support portion of the tension pulley 3 is arranged with an offset, in other words, a structure in which the tension pulley 3 is arranged at a position protruding forward from the tip of the support shaft 11.

The automatic tensioner A has a function of restricting the movement of the tension pulley 3 so as to attenuate the vibration and impact from the belt B while allowing the movement of the tension pulley 3 in accordance with the fluctuation in the tension of the belt B. It has a structure having.

That is, when the tension of the belt B is gradually reduced, the arm 2 and the tension pulley 3 are driven by the torsion restoring force (elastic biasing force in the circumferential direction) of the torsion coil spring 4.
Tilts to the left in FIG. 2 to keep the tension of the belt B constant. On the other hand, when the tension of the belt B gradually increases, the arm 2 and the tension pulley 3 tilt to the right in FIG. 2 against the torsion restoring force of the torsion coil spring 4 to keep the tension of the belt B constant.

When an intense vibration or impact is applied to the auto tensioner A from the belt B, the vibration or impact is transmitted to the boss portion 21 of the arm 2 supporting the tension pulley 3. Since the boss 21 of the arm 2 is pressed against the friction plate 5 by the extension restoring force (elastic biasing force in the axial direction) to generate frictional resistance,
The vibration and shock are absorbed and attenuated.
Unnecessary rocking is suppressed. As a result, the position of the tension pulley 3 does not substantially change, and the tension on the belt B is kept constant.

Hereinafter, each component of the auto tensioner A will be specifically described.

The fixed case 1 is fixed to an object to which a belt transmission (not shown) is provided.
, A cover part 12 and a bolt mounting piece 13. The support shaft 11 is formed so that its entire outer peripheral shape is substantially cylindrical. The cover part 12
It is formed so as to extend radially outward from the base end side of the support shaft 11 and further surround the outer periphery of the support shaft 11. The bolt attachment piece 13 is formed to protrude radially outward on the outer periphery of the cover portion 12. Here, the support shaft 11 is formed of a metal material such as JIS standard S55C, for example.
The bolt mounting piece 13 is an integral member formed by die casting of an aluminum alloy or the like, and is spline-fitted (serration-fitted) so that the support shaft 11 is prevented from rotating in a spline hole formed in the cover portion 12. The support shaft 11 and the cover 12 are integrated.

The arm 2 is supported by being fitted to the support shaft 11 of the fixed case 1 so as to be rotatable around an axis P1 which is the center thereof. A pulley support portion 22 for supporting the pulley 3 rotatably around an axis P2 parallel to the axis P1 is formed. The boss portion 21 has a needle roller bearing 7 on the outer periphery of the support shaft 11.
Is rotatably fitted via the. The pulley support 22 is
The boss 21 is provided to project in a direction opposite to the direction in which the boss 21 projects. The arm 2 is manufactured by die casting using an aluminum alloy or the like.

The tension pulley 3 is rotatably supported by a pulley support portion 22 of the arm 2 via a rolling ball bearing 9 and is manufactured by press molding. The tension pulley 3 is attached by a bolt 8a and a nut fastened to the pulley support 22 of the arm 2. In addition, the above-mentioned rolling ball bearing 9 is a tension pulley 3
And the outer peripheral surface of the pulley support portion 22 of the arm 2 are press-fitted.

The torsion coil spring 4 is torsionally compressed in an annular space between the outer peripheral surface of the boss portion 21 of the arm 2 and the inner peripheral surface of the cover portion 12 of the fixed case 1 without contacting the respective surfaces. It is arranged in. The torsion coil spring 4 elastically urges the arm 2 in one rotation direction (counterclockwise direction in FIG. 2) by the torsion restoring force, and the boss portion of the arm 2 by the axial restoring force. 21 is pressed against the friction plate 5 and the boss 21 is pressed.
To provide frictional resistance. This torsion coil spring 4
Bent portions 41, 4 bent radially outward on both ends of
2 are provided integrally, and these bent portions 41 and 4 are provided.
2 are respectively locked by a locking portion (not shown) provided on the cover portion 12 and a locking portion (not shown) provided on the cover portion 10 around the boss portion 21 of the arm 2.

The friction plate 5 includes a boss portion 21 of the arm 2 and a front end surface portion 15 connected to the cover portion 10, and a friction plate pressing plate 6 fixed to the support shaft 11 by caulking the front end of the support shaft 11. It is provided in a state sandwiched between
The torsion coil spring 4 is pressed against the boss 21 and the friction plate pressing plate 6 with a required pressure by the restoring force of the torsion coil spring 4, thereby imparting rotational resistance to the boss 21 of the arm 2. Here, in the figure, K is the friction plate pressing plate 6
This is the caulking section.

The friction plate pressing plate 6 is an annular plate manufactured by press-forming a rolled structural steel plate, for example.
The support shaft 1 is fixed in a detent state with respect to the support shaft 1.
One and one.

This embodiment is characterized in that, for example, a shell type needle roller bearing 7 as a radial type roller bearing is interposed between the support shaft 11 and the boss 21 of the arm 2.

The shell-type needle roller bearing 7 includes a shell-shaped outer ring 31 formed by press-forming a metal material, a plurality of rollers R housed at several locations on the inner circumference of the outer ring 31, and an outer ring 3.
The retainer 32 is housed on the inner periphery of the outer ring 1 and holds the rollers R so as to be able to rotate. The seals 30 are fixed to the inner periphery of both ends in the axial direction of the outer race 31 on both sides of the retainer 32.

The shell-type needle roller bearing 7 has an outer ring 31 fixed to the inner periphery of the boss portion 21 of the arm 2 by press-fitting, and the outer peripheral surface of the support shaft 11 is used as the inner ring raceway of the roller R group. ing.

As described above, since the support shaft 11 is used as the inner raceway of the roller R, a region other than the caulked portion K on the outer peripheral surface of the support shaft 11 is hardened by induction hardening or the like.
Along with high rigidity, it has improved wear resistance.

The seals 30, 30 are formed by attaching a plurality of lips to the inner periphery of an annular core bar, and each lip is in contact with the outer peripheral surface of the support shaft 11.

The outer race 31 has one axial end bent radially inward during press forming, and the other axial end bent radially inward after the rollers R and the seals 30, 30 have been assembled. Is done.

Each roller R of the shell-type needle roller bearing 7
Sets the length range in the longitudinal direction along the axis P1 of the boss 21 of the arm 2. Each seal 30, 3
0 is the needle roller bearing 2 as shown in FIG.
In a state sandwiched between the outer ring 31 of 0 and the retainer 32 for holding each roller R, it is incorporated at both ends in the direction of the axis P1. Therefore, as shown in FIG.
The seal 30 is in close contact with the inner peripheral surface of the outer ring 31 and the outer peripheral surface of the support shaft 11 to perform sealing. With this configuration, even if a moment is generated in the arm 2 due to the belt load caused by the belt B being wound around the arm 2, the inclination of the arm 2 due to the moment is restricted by the shell-type needle roller bearing 7. Will be.

It should be noted that the present invention is not limited to the above-described embodiment, and various applications and modifications are conceivable. An example will be described below. (1) In the above embodiment, the support shaft 11 may be made of an aluminum alloy. In this case, the outer periphery of the support shaft 11 is provided with an inner raceway of the roller R group of the shell type needle roller bearing 7. It is preferable to externally fix a metal sleeve for fitting by press fitting or the like. A specific example is shown in FIG.
That is, as shown in FIG. 3, the support shaft 11 that supports the shell-type needle roller bearing is provided with a support shaft main body portion 1 that is formed in a shaft shape.
1A is made of an aluminum alloy, and a steel cylinder 1 made of, for example, S55C is provided on the outer peripheral surface of the spindle main body 11A.
1B (preferably induction hardened) is press-fitted. In the case shown in FIG. 3, the outer peripheral shape of the spindle main body portion 11A is tapered to have a tapered conical shape, so that the draft angle when molding by aluminum die casting is used. The inner peripheral shape is a taper that matches the taper. Although not shown,
The shell-type needle roller bearing is provided so as to be fitted to the cylindrical body 11A, and the boss at the base end of the arm is fitted to the needle roller bearing. With this configuration, there is an advantage that the weight of the support shaft 11 can be reduced as compared with the case where the entirety of the support shaft 11 is made of steel. (2) In the above embodiment, the rollers R of the roller bearing 7 are in a single row. However, a structure in which two or more rows are provided in the axial direction or a structure without a retainer, that is, a full roller structure may be used. Also, various roller bearings can be used instead of the shell-type needle roller bearing. Further, the seals 30, 30 may be provided outside the bearing. (3) In the above-described embodiment, an auto tensioner having an offset structure has been described as an example. However, the present invention can be applied to an auto tensioner in which a pulley is disposed substantially at the center of the support shaft in the axial direction.

[0037]

According to the first to sixth aspects of the present invention, since the arm is configured to be rolled and supported on the support shaft via a roller shaft having a high load-loading capability and a small radial dimension, the arm is provided. The rigidity and smooth operation of the support part between the shaft and the spindle can be improved, and in addition to the improvement of the followability due to the fluctuation of the tension, the durability of the product is improved, and it can greatly contribute to the improvement of reliability. Thus, the problem that the arm is unduly tilted due to uneven wear of the bush can be solved.

In particular, according to the second aspect of the present invention, even in an auto tensioner having an offset structure in which a high load is applied to an arm supporting portion, the arm supporting rigidity is improved, and the durability of the auto tensioner is increased. This is advantageous in smooth operation.

According to the third aspect of the present invention, the roller bearing is
Shell type outer ring, having a plurality of rollers, since the outer peripheral surface of the spindle is used as the inner ring raceway of the roller group, the radial width of the bearing may be small, Since there is dimensional compatibility with the conventional resin bush, it is possible to avoid a large dimensional design change or a change in the machining process of the support shaft or a place where the one end of the arm is fitted to the support shaft.

According to the fourth aspect of the present invention, the seal can sufficiently prevent foreign matters such as abrasion powder and moisture from the friction plate from entering the bearing, and in particular, the seal is built in the outer ring. The workability can be improved as compared with the case where the seal is separately assembled.

According to the fifth aspect of the present invention, even if the roller group is brought into contact with the roller group, the area of the outer peripheral surface of the support shaft which is the inner raceway of the roller group is hardened. Since sufficient abrasion resistance can be exhibited, high durability and smooth operation can be further improved.

[Brief description of the drawings]

FIG. 1 is a developed sectional view showing an example of an auto tensioner of the present invention.

FIG. 2 is a front view showing an example of the auto tensioner of the present invention.

FIG. 3 is a longitudinal sectional side view showing a support shaft of an auto tensioner according to another embodiment.

FIG. 4 is an explanatory view showing an action form of a moment load in a conventional auto tensioner.

[Explanation of symbols]

 Reference Signs List A auto tensioner 11 support shaft 2 arm 3 tension pulley 7 roller bearing (needle roller bearing) 30 oil seal P1 shaft center of support shaft 11 roller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J016 AA02 BB03 CA03 3J049 AA01 BB05 BB10 BB15 BB25 BC03 CA04 3J101 AA14 AA24 AA32 AA42 AA52 AA62 AA72 BA54 BA70 BA73 DA09 EA01 FA31 GA60

Claims (5)

[Claims] 1. A fixed support shaft, an arm which is resiliently urged in one rotation direction with one end side rotatably fitted to the support shaft, and pivoted to the other end side of the arm. An auto-tensioner having a tension pulley supported so as to be supported, wherein the arm is supported on the support shaft via a radial type roller bearing. 2. The auto-tensioner according to claim 1, wherein the tension pulley is arranged in an axial direction with respect to the support shaft. 3. The auto-tensioner according to claim 1, wherein the roller bearing has a shell-type outer ring and a plurality of rollers, and an outer peripheral surface of the support shaft is used as an inner ring raceway of the roller group. An auto tensioner characterized by being made. 4. The auto-tensioner according to claim 3, wherein seals are attached to both ends of the outer race of the roller bearing in the axial direction. 5. The auto-tensioner according to claim 3, wherein the support shaft is made of a metal material, and an outer circumferential surface of the auto-tensioner is hardened in an area serving as an inner raceway of the roller group. And an auto tensioner.