JPH0783295A - Auto tensioner - Google Patents

Abstract

PURPOSE:To prevent a deformation or a crack of a spring support as well as to increase the squeezing force of the spring support to a boss. CONSTITUTION:A spring support is a divided structure having plural spring pieces 11a.... When the winding diameter of a twisting coil spring 3 is reduced so as to fasten the spring support, the spring pieces 11a... of the spring support contact to the outer peripheral surface of the boss 2b of a rotary member, and the squeezing force of the spring support to the boss 2b is given by the whole body of the spring support. As a result, the squeezing force of the spring support to the boss 2b is increased, and a large damping force can be obtained from not only the reaction of the boss 2b against the increased squeezing force, but also operated from a fastening force of the twisting coil spring 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an automatic tensioner, in particular, a predetermined tension to a V-belt or the like for driving an auxiliary machine by an automobile engine, and automatically changes a damping force in accordance with a change in the tension. Regarding the automatic tensioner that was made to let.

[0002]

2. Description of the Related Art As described in, for example, U.S. Pat. No. 4,473,362 and drawings, the span between pulleys of a belt wound between a drive pulley and a plurality of driven pulleys is pressed to press the drive pulley. It is known that autotensioners are used to transfer rotational force to all driven pulleys.

In such an automatic tensioner, as shown in FIGS. 3 and 4, a rotary member 2 is rotatably supported by a fixed member 1 which can be fixed to a fixed body such as an automobile engine, and the fixed member is fixed. A torsion coil spring 3 is interposed between the rotary member 2 and the rotary member 2 to bias the rotary member 2 in a predetermined direction with respect to the fixed member 1.

The fixed member 1 has a bottomed cylindrical rear cup portion 1a and a cylindrical shaft portion 1b extending axially from the center of the bottom portion of the rear cup portion 1a.
A base end side locking hole 1c penetrating the wall portion in the radial direction is formed in the wall portion a.

On the other hand, the rotating member 2 has a front cup portion 2 whose opening faces the opening of the rear cup portion 1a.
a, a boss portion 2b extending in the axial direction from the center of the bottom portion of the front cup portion 2a, and externally fitted to the shaft portion 1b of the fixing member 1 from its tip end side, and a boss portion 2b protruding on the outer periphery of the front cup portion 2a. It has an arm portion 2c which is provided at the tip and has a pulley 4 rotatably supported by an axis parallel to the axis of the boss 2b, and is rotatably supported by the fixing member 1 at the boss 2b. . A belt to which a predetermined tension is applied, such as a V-belt for transmitting auxiliary machinery in an automobile engine, is wound around the pulley 4. A front end side locking hole 2d is formed in the wall portion of the front cup portion 2a so as to penetrate the wall portion in the radial direction.

The main body of the torsion coil spring 3 is left-handed, and each of the end portions 3a and 3b on the base end side and the tip end side protrudes radially outward from the main body.
The proximal end 3a is a proximal locking hole 1c in the wall of the rear cup 1a of the fixing member 1, and the distal end 3b is a distal locking hole in the peripheral wall of the front cup 2a of the rotating member 2. 2d are respectively radially penetrated and locked, so that each end 3a, 3b is locked in each locking hole 1c,
Movement in the circumferential direction is restricted by 2d. The torsion coil spring 3 operates in the direction in which the main body expands with both ends 3a and 3b locked, thereby urging the rotating member 2 to rotate counterclockwise in FIG. It is done like this.

A cylindrical spring support 5 is interposed between the base end side of the torsion coil spring 3 and the boss portion 2b, and the inner peripheral surface of the spring support 5 is the outer peripheral surface of the boss portion 2b. It is possible to slide on. As shown in FIG. 5, the spring support 5 is provided with a tubular portion 5a located outside the boss portion 2b and an outer portion which is continuously provided on the proximal opening edge of the tubular portion 5a and which contacts the bottom surface of the rear cup portion 1a. And an orientation flange 5b. Then, the outward flange 5b is pressed against the bottom surface of the rear cup portion 1a by the pressing force of the torsion coil spring 3, whereby the spring support 5 is fixed to the fixing member 1 side. Further, in this fixed state, when the front cup portion 2a rotates in the clockwise direction in FIG. 6, the main body of the torsion coil spring 3 contracts, so that the spring support 5 is tightened and its inner peripheral surface is bossed. It comes into pressure contact with the outer peripheral surface of the portion 2b, and this also produces a damping force.

Of the fixing member 1 and the rotating member 2, the fixing member 1 is made of synthetic resin, and the rotating member 2 is made of metal such as aluminum alloy. The outer peripheral surface of the shaft portion 1b of the fixed member 1 and the inner peripheral surface of the boss portion 2b of the rotating member 2 are both formed in a tapered cross-section with a small diameter on the tip side, and a synthetic resin is provided between them. The tubular bush 6 is interposed.

A boss portion 2b externally fitted to the shaft portion 1b.
Are secured by a plate member 7 fixed to the tip of the shaft portion 1b. The plate member 7 is made of metal and has a disc shape, and a hole for fitting the shaft portion 1b is provided in the central portion thereof. Then, the boss portion 2 of the plate member 7
A plate-shaped resin member 14 that is in sliding contact with the tip surface of the boss portion 2b and receives the thrust load is integrally joined to the b side.

Therefore, the belt is wound around the pulley 4 of the automatic tensioner, and the inner peripheral surface of the boss portion 2b of the rotating member 2 and the shaft portion 1b of the fixed member 1 in the automatic tensioner are wound.
Between the (bush 6) outer peripheral surface and between the boss portion 2b (bush 6) outer peripheral surface and the spring support 5 inner peripheral surface,
When the tension of the belt decreases in the state where the belt force and the urging force of the torsion coil spring 3 are combined to generate the damping force, the damping force of the fixed member 1 to the rotating member 2 decreases due to the decrease of the belt force. Become. Then, the rotating member 2 is easily rotated, and the followability of the pulley 4 with respect to the belt is increased, which makes it possible to quickly prevent the tension of the belt from being lowered.
On the other hand, with respect to the tension of the belt, the damping force is also increased due to the increase of the belt force, which makes it possible to apply a large resistance force to the pulley 4 and prevent the belt from fluttering.

[0011]

However, even if the torsional force acts on the torsion coil spring 3 to reduce the winding diameter, the cylindrical spring support 5 has a diameter of the boss portion 2b of the rotating member 2. Since it is formed to be larger than the above, a clearance is generated between them, and as shown in FIG. 6, the spring support 5 and the boss portion 2b contact only partly,
As a result, the pressing force of the spring support 5 against the boss portion 2b was only the reaction force of the contact portion. Further, even if the spring support 5 is tightened by reducing the winding diameter, there is a possibility of deformation or cracking due to the clearance between the inner peripheral surface of the spring support 5 and the outer peripheral surface of the boss portion 2b as described above. .

The present invention has been made in view of the above circumstances, and provides an auto tensioner in which the pressing force of the spring support against the boss portion is enhanced and the spring support is prevented from being deformed or cracked.

[0013]

According to the present invention, a boss portion of a rotating member is rotatably fitted to a shaft portion of a fixed member, and a pulley for pressing a belt is attached to the boss portion. A torsion coil spring that is rotatably supported by an arm member with an axis parallel to and that biases the rotating member in a predetermined direction with respect to the fixing member is provided between the fixing member and the rotating member. An automatic device that is interposed via a spring support, presses the belt against the pulley by the rotational urging force of the rotating member to apply a predetermined tension, and changes the damping force according to the fluctuation of the tension. Based on a tensioner, the spring support has a plurality of spring pieces divided in the axial direction.

[0014]

Since the spring support has a split structure having a plurality of spring pieces that are split in the axial direction, when the spring support is tightened by reducing the winding diameter of the torsion coil spring, the inner surface of each spring piece of the spring support is reduced. Comes into contact with the outer peripheral surface of the boss portion of the rotating member, and the pressing force of the spring support to the boss portion is given by the entire spring support, so that the pressing force of the spring support to the boss portion is increased. Then, not only the reaction force against the increased pressing force but also the tightening force of the torsion coil spring acts to obtain a large damping force.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. Since the basic structure of the embodiment of the present invention is the same as that shown in FIGS. 3 and 4, the same components are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in FIG. 1, the spring support 11 of the torsion coil spring 3 has a plurality of spring pieces 11a, ... Divided in the axial direction, and by the plurality of spring pieces 11a ,. Cylindrical portion 11A located on the outer periphery of the shaft portion 1a of
Flange part 1 that is connected to one end of the and extends radially outward
1B and the like. Therefore, each spring piece 11a, ... Of the spring support 11 changes in the radial direction due to the change in the winding diameter of the torsion coil spring 3.

According to the above-mentioned structure, the spring support 11 has a split structure having a plurality of spring pieces 11a, ... Divided in the axial direction, so that the spring support 11 can be formed by reducing the winding diameter of the torsion coil spring 3. When is tightened, the spring pieces 11a, ... Of the spring support 11 are displaced radially inward as shown in FIG. 2 and come into contact with the outer peripheral surface of the boss portion 2a of the rotating member 2. , The spring support 11 hits well, the pressing force of the spring support 11 against the boss portions 11a, ... Is increased, and the frictional force is increased. Then, in addition to the increased reaction force from the boss portion 2b of the rotating member 2, the tightening force by the torsion coil spring 3 also acts to obtain a large damping force. Also, since all the spring pieces 11a ... Contact the boss portion 2b,
There is no clear lance between the boss portion 2b and the spring support 11, and the spring support 11 is prevented from being deformed or damaged.

[0018]

As described above, according to the present invention, since the spring support has the divided structure, when the spring support is tightened by the reduction of the winding diameter, each spring piece of the spring support comes into contact with the periphery of the boss portion. As a result, the pressing force of the spring support against the boss is increased. In addition to the reaction force from the boss portion against the increased pressing force, the tightening force of the torsion coil spring also acts,
Since a large damping force is obtained and all the spring pieces come into contact with the boss portion, it is possible to prevent the spring support from being deformed or damaged.

[Brief description of drawings]

FIG. 1 is a perspective view of a spring support.

FIG. 2 is an explanatory diagram of an operation.

FIG. 3 is a sectional view of a conventional auto tensioner.

FIG. 4 is a front view of the same.

FIG. 5 is a perspective view of a conventional spring support.

FIG. 6 is an explanatory diagram of the same operation.

[Explanation of symbols]

 1 Fixed member 1b Shaft part 2 Rotating member 2b Boss part 3 Torsion coil spring 11 Spring support 11a Spring piece

Claims (1)

[Claims] 1. A boss portion of a rotating member is rotatably fitted to a shaft portion of a fixed member, and a pulley for pressing a belt is rotatably fitted to the boss portion with an axis parallel to the axis of the boss portion. Is rotatably supported via, and between the fixed member and the rotating member,
A torsion coil spring for biasing the rotating member in a predetermined direction with respect to the fixed member is interposed via a spring support, and the rotating biasing force of the rotating member causes the pulley to press the belt with a predetermined tension. And the damping force is changed according to the fluctuation of the tension, wherein the spring support has a plurality of spring pieces divided in the axial direction.