JP2002310248A - Thin tensioner and assembly method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To store a torsional coil spring provided with sufficient energizing force in a compact fixing member. SOLUTION: An outside diameter of the torsional coil spring 50 is larger than an inside diameter of a spring storage space and is larger than a length of an axis. A one end part 501 of the torsional coil spring 50 is engaged with a cup bottom face 224, and the other end part 502 thereof is engaged with a lid part 310. The lid part 310 is rotated in the direction in which the outside diameter of the torsional coil spring 50 is reduced. After that, the torsional coil spring 50 is compressed in the axial direction. A pivot bolt 23 is screw-fitted into a female screw part 311, and an arm 30 is fixed to the fixing member 20 so as to swing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensioner used in a belt system for transmitting the driving force of an automobile engine to another driven pulley using a single driving belt.

[0002]

2. Description of the Related Art Conventionally, in a transmission device in which a single driving belt transmits driving force to a plurality of devices, a tensioner that prevents slack of the driving belt and applies a predetermined tension to the driving belt is known. Such a tensioner includes, for example, a fixing member fixed to an engine block or the like, an arm swingable with respect to the fixing member, and a pulley rotatably attached to a tip of the arm. A drive belt is wound around the side surface of the pulley, and the drive belt is urged in a direction to tighten the drive belt, thereby preventing slack. In general, a torsion coil spring having a predetermined spring constant is accommodated in the fixed member, thereby generating an urging force.

In recent years, with the downsizing of engines, downsizing of tensioners is also required. Therefore, for example, when the size of the fixing member is reduced, the space for accommodating the torsion coil spring is reduced, and the torsion coil spring that can be accommodated is also limited to a small one. On the other hand, with the recent improvement in engine performance, tensioners are also required to have considerable biasing force. A tensioner having a considerable urging force needs a torsion coil spring having a considerable spring constant and a considerable spring urging force. The spring constant and spring urging force are determined by the coil length, wire diameter, etc. Is done. Therefore, a tensioner having a necessary urging force needs a space capable of accommodating a considerable spring, and a tensioner having a small fixing member cannot accommodate a torsion coil spring having a sufficient torque, and a belt is not provided. May be insufficient.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides a tensioner capable of obtaining a sufficient urging force on a drive belt while reducing the thickness and size of a fixing member. The purpose is to:

[0005]

SUMMARY OF THE INVENTION A thin tensioner according to the present invention comprises a fixing member having a cup portion having a predetermined inner diameter, an arm swingably mounted on the fixing member, and an outer diameter larger than the predetermined inner diameter. And a torsion coil spring which is housed in the cup portion by being twisted in a direction in which the outer diameter is reduced, and biases the arm in a predetermined direction.

[0006] Preferably, the torsion coil spring comprises:
One end engages a first engagement portion provided in the fixing member,
The other end is engaged with a second engaging portion provided in the arm, and the relative position between the second engaging portion and the first engaging portion is determined when the torsion coil spring is engaged. Differs when mounted on

For example, the axial length of the torsion coil spring is relatively shorter than the outer diameter.

For example, at least one friction member is provided between the cup portion and the arm and provides frictional resistance to the swing of the arm. The friction member is formed of a cylindrical portion and a flange portion protruding from the lower end of the cylindrical portion toward the inside of the cup portion and the arm, and has an L-shaped cross section.

The method of assembling a thin tensioner according to the present invention includes a first step of twisting a torsion coil spring having an outer diameter larger than the inner diameter of the cup portion to make the outer diameter smaller than the inner diameter; A second step of interposing between the section and the arm.

The method of assembling a thin tensioner according to the present invention includes a first step of engaging one end of a torsion coil spring having an outer diameter larger than the inner diameter of the cup with the cup, and the other end of the torsion coil spring. A second step of engaging the part with the arm, and rotating the arm,
A third step of twisting the torsion coil spring to make the outer diameter smaller than the inner diameter, a fourth step of compressing the torsion coil spring by approaching the arm to the cup portion and housing the arm in the cup portion, And a fifth step of rotatably fixing the fifth step.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a thin tensioner according to the present invention will be described below with reference to the drawings.

FIG. 1 is a view schematically showing a belt system of an automobile engine using a thin tensioner according to a first embodiment. This belt system includes a drive pulley 11 connected to an output shaft of an engine, a pulley 12 for an air conditioner, a pulley 13 for a power steering device, a driven pulley 14 for an alternator, and a thin tensioner (hereinafter referred to as a tensioner) 10. Have. A single drive belt 17 is suspended between each pulley, and the drive belt 17 transmits the rotational driving force of the drive pulley 11 to each pulley. In the figure, the drive belt 17 is driven in a clockwise direction, and the tensioner 10 urges the drive belt 17 from the outside to tension the drive belt 17.

The tensioner 10 has a fixing member 20 fixed to an engine block (not shown). Fixing member 2
The arm 30 is swingably fixed to 0, and the pulley 40 is rotatably attached to the arm 30. Tensioner 1
0 urges the arm 30 in a direction such that the pulley 40 tensions the drive belt 17. The drive belt 17 is wound around the outer peripheral surface of the pulley 40, and the pulley 40 rotates with the rotation of the drive belt 17. The drive belt 17 is
The arm 30 is swung, and the pulley 40 is mounted in a state determined at a position indicated by a broken line in the figure.

FIG. 2 is a view showing a cross section of the tensioner 10. The fixing member 20 includes a mounting portion 21 and a cup portion 22 opened upward in the drawing. The mounting portion 21 has a mounting hole (not shown) for fixing the fixing member 20 to the engine block.

The cup portion 22 is provided with a bolt engaging portion 221 extending from substantially the center of the cup bottom surface 224 toward the opening. A cylindrical hole 222 is formed in the bolt engaging portion 221. A pivot bolt 23 as a stepped bolt is inserted into the cylindrical hole 222 from the cup bottom surface 224 side toward the opening side. The pivot bolt 23 has a column 231. When the pivot bolt 23 is inserted into the cylindrical hole 222, a gap 25 is formed between the cylindrical portion 231 of the pivot bolt 23 and the bolt engaging portion 221, and the pivot bolt 23 is connected to the cylindrical hole 222 of the bolt engaging portion 221. It is rotatable in the axial direction. The pivot bolt 23 has a head 232 having an outer diameter larger than the inner diameter of the cylindrical hole 222, and the head 232 restricts the upward movement of the pivot bolt 23 along the axial direction of the cylindrical hole 222. Is done.

An arm 30 is swingably mounted on the upper portion of the cup portion 22. The arm 30 includes a bottomed cylindrical lid 310 that opens toward the cup bottom surface 224. The outer diameter of the lid 310 is smaller than the inner diameter of the cup 22, and the lid 3
10 is fitted into the cup portion 22. Thereby, a spring accommodating space surrounded by the inner wall surface 225 of the cup bottom surface and the lid 310 is provided. The inside diameter of the cup bottom side inner wall surface 225 and the inside diameter of the lid 310 both have D2.

At the center of the lid 310, a cup bottom surface 224 is provided.
Female screw part 3 which extends toward
11 are provided. A male screw part 233 provided on the pivot bolt 23 is screwed into the female screw part 311. Thereby, the pivot bolt 23 is fixed integrally with the arm 30. As described above, since the pivot bolt 23 is rotatable in the axial direction of the cylindrical hole 222 of the fixing member 20 (the bolt engaging portion 221), the arm 30 is attached to the fixing member 20 with the pivot bolt 23 as the central axis. On the other hand, it can swing.

The torsion coil spring 50 is accommodated in a spring accommodating space surrounded by the lid 310 and the cup inner peripheral surface 225 and having an inner diameter D2. The torsion coil spring 50 is formed by spirally winding a metal material having a predetermined coil length.
One end 501 of the torsion coil spring 50 is engaged with the cup bottom surface 224 of the cup 22, and the other end 502 is engaged with the lid 310. The torsion coil spring 50 is twisted by a predetermined amount as described later, and
The cup 22 and the lid 31 are compressed in the axial direction of FIG.
0 is interposed.

A bushing 32 formed of, for example, synthetic resin and having an L-shaped cross section is interposed between the surfaces where the cup portion 22 and the lid portion 310 are close to each other. The bushing 32 includes a cylindrical portion 321 interposed between an inner peripheral surface 223 of the cup portion 22 and an outer peripheral surface 312 of the lid portion 310, and a cylindrical portion 3
21 is formed from the lower end of the cup portion 22 and the flange portion 322 extending inward of the lid portion 310. Since such a bushing 32 is interposed on the surface where the cup portion 22 and the lid portion 310 are close to each other, when the arm 30 swings, a frictional force is generated between the surface where the cup portion 22 and the lid portion 310 are close to each other. Due to this frictional force, a rotational resistance is given to the arm 30, and the vibration of the drive belt 17 is attenuated. Further, the flange portion 322 of the bushing 32 serves as a thrust bearing against a downward load due to the weight of the lid portion 310.

A cushioning member 24 is interposed between the head 232 of the pivot bolt 23 and the cup bottom 224,
Abrasion, etc., caused by collision of the cup with the cup bottom surface 224.
The buffer member 24 is a thrust bearing that bears the axial force of the pivot bolt 23.

The arm 30 has a pulley mounting portion 320 protruding from the opposite side of the cup bottom surface 224. The pulley 40 is rotatably fixed to the pulley mounting portion 320 via a ball bearing 42. A female screw part 323 is formed at the center of the pulley mounting part 320. The pulley bolt 41 is screwed into the female screw portion 323, and the pulley 40 is
Prevents deviation from zero. A dust shield 43 for preventing dust from entering is provided between the head of the pulley bolt 41 and the ball bearing 42.

FIG. 3 is a plan view of the fixing member 20 as viewed from the opening side. The first coil supporting portion 2 is provided on the cup bottom surface 224.
5 and the second coil support 26 are formed. The first coil support portion 25 has a predetermined height from the cup bottom surface 224 and has a crescent shape projecting from the cup bottom side inner peripheral surface 225 toward the axial direction of the fixing member 20. That is,
The first coil support portion 25 extends in the axial direction of the cup portion 22,
It has a plane 251 of a predetermined height. On the other hand, the second coil supporting portion 26 has a predetermined height from the cup bottom surface 224 and is provided concentrically with the cylindrical hole 222. The second coil support portion 26 has an arc-shaped protruding surface 261. The torsion coil spring 50 is accommodated along the inner peripheral surface 225 of the cup bottom surface. That is, the inner diameter D2 of the inner peripheral surface 225 on the cup bottom surface side is the diameter of the space that can accommodate the torsion coil spring 50.

Although not shown, members similar to the first coil support 25 and the second coil support 26 are also provided on the surface of the cover 310 on the opening side. As mentioned above,
The lid 310 has the same inner diameter as the inner diameter D2 of the cup inner peripheral surface 225, and the inner diameter D2 of the lid 310 is the diameter of the space that can accommodate the torsion coil spring 50.

FIG. 4 is a view of the torsion coil spring 50 as viewed from the arm 30 side. Torsion coil spring 5
0 has a spiral portion 503 wound with a constant diameter. The bent portion 505, which is the end of the spiral portion 503, bends at an angle θ toward the spiral axis. From the bent portion 505, one end portion 501 having a length B engages with the cup portion 22 and extends linearly. Similarly, the other end portion 502 has a length B and extends linearly from the other bent portion 505. This torsion coil spring 50 has the same shape even if it is turned upside down.

The size of the tensioner 10 is required to be reduced with the recent downsizing of the engine. Thereby, the cup part 2
2 is also reduced in size, and the space for accommodating the torsion coil spring 50 is reduced. On the other hand, with the recent improvement in engine performance, the tensioner 10 has a large urging force,
That is, a tensioner that accommodates the torsion coil spring 50 having a predetermined spring constant is required. The spring constant of the torsion coil spring 50 is proportional to the length of the torsion coil spring 50 (coil length). That is, a torsion coil spring having a predetermined spring constant requires a predetermined coil length corresponding to the spring constant.

The torsion coil spring 50 used in this embodiment has a considerable coil length according to a required spring constant, and is formed by being wound around an outer diameter D1. Outer diameter D1
Is a natural length and is larger than the inner diameter D2. Therefore, when the torsion coil spring 50 is not loaded, the lid 31
0 and the inner peripheral surface 225 on the bottom surface of the cup.
Cannot be accommodated in the spring accommodation space having In the present embodiment, by twisting the torsion coil spring 50 having an equivalent coil length for obtaining a necessary urging force, the inner diameter D2
To an outside diameter that can be accommodated. Thereby, the inner diameter D2
A coil spring 50 having a larger outer diameter D1 can be accommodated.

When the outer diameter D1 of the torsion coil spring 50 is increased, the amount of reduction in the outer diameter due to the torsion increases even at the same torsion angle. Therefore, for the torsion coil spring 50 having a predetermined coil length, the number of turns is reduced and the outer diameter D1 is increased. As a result, the amount of reduction in the outer diameter due to the torsion increases, and the torsion coil spring 50 having a larger urging force can be accommodated in a limited space. Further, in the present embodiment, the vertical interval (winding pitch) between the spiral portions 503 is formed large. That is, the inclination angle of the spiral portion 503 is increased. With the configuration of the winding pitch, the torsion coil spring 50 can be easily installed in the cup part 22 and the lid part 310 as described later.

Referring again to FIG. 3, one end of the torsion coil spring 50 is provided between the flat surface 251 of the first coil support portion 25 and the support outer peripheral surface 262 of the second coil support portion 26 facing the flat surface 251. The unit 501 is provided. The width between the flat portion 251 and the support outer peripheral surface 262 is substantially the same as the wire diameter of the torsion coil spring 50. Also, the plane 25
The length B ′ of one is longer than the length B of one end 501. As a result, the one end portion 501 is locked to the flat surface 251 and the support outer peripheral surface 262.

Further, the angle θ ′ formed between the tangent of the inner peripheral surface 225 of the cup bottom surface and the plane 251 is substantially the same as the angle θ of the bent portion 505 of the torsion coil spring. Therefore, when the one end portion 501 is placed between the flat surface 251 and the support outer peripheral surface 262, the outer peripheral side of the bent portion 505 is locked between the inner peripheral surface 225 on the cup bottom surface side and the flat surface 251. Further, since the protruding surface 261 of the second coil supporting portion 26 is formed in an arc shape corresponding to the bent portion 505, the inner peripheral side of the bent portion 505 abuts on the protruding surface 261. That is, when the one end portion 501 is locked between the flat surface 251 and the support outer peripheral surface 262, the bent portion 505 of the coil spring 50 becomes
25, a flat surface 251 and a protruding surface 261.
At this time, a part of the spiral part 50 near the bent part 505
3 is in contact with and is supported by the inner peripheral surface 225 of the cup bottom surface.
As described above, the spiral pitch of the spiral portion 503 is formed to be large, so that the one end portion 501 has the flat surface 251 and the support outer peripheral surface 26.
2, the portion where the spiral portion 503 contacts the inner peripheral surface 225 of the cup bottom surface side is kept to a minimum. Thereby, the spiral portion 503 is formed on the inner peripheral surface 2 on the cup bottom surface side.
25 is easily prevented from being caught on one end 50.
1 can be locked between the flat surface 251 and the support outer peripheral surface 262. As described above, the one end 501 side is locked to the cup 22.

As described above, the same member as the first coil support 25 and the second coil support 26 is provided on the surface of the cover 310 on the opening side.
The other end 502 of the zero has the same shape as the one end 501. Therefore, the other end 502 side is locked by the lid 310. The torsion coil spring 50 has the same shape even when it is turned upside down.
It is also possible to lock the other end 502 to the cup 22 at zero.

Next, the assembly of the auto tensioner 10 will be described. As described above, one end portion 501 of the torsion coil spring 50 is locked to the cup portion 22. Similarly, the other end 502 of the coil spring 50 is locked to the lid 310. In this state, the torsion coil spring 5
Since the outer diameter D1 of 0 is larger than the inner peripheral surface 225 of the cup bottom surface side and the inner diameter D2 of the lid 310, it cannot be accommodated in the spring accommodating space surrounded by the inner peripheral surface 225 of the cup bottom surface and the lid 310.

Both ends 50 of the torsion coil spring 50
In the state where the first and the second 502 are locked to the cup portion 22 and the lid portion 310, a part of the spiral portion 503 of the cup portion 22 is brought into contact with the inner peripheral surface 225 of the cup bottom side, and the torsion coil spring 5
0 and the cup part 22 are fixed. In this state, the lid 310
Is rotated in a direction in which the outer diameter D1 of the torsion coil spring 50 is reduced, so that the torsion coil spring 5 is rotated.
Twist 0. After that, the torsion coil spring 50 is compressed by bringing the lid 310 closer to the cup 22. When the lid 310 is located at a position close to the cup 22, the pivot bolt 23 is
1 and fixed integrally with the pivot bolt 23 and the lid 310. Through the above steps, the torsion coil spring 50 can be accommodated in the spring accommodation space having the inner diameter D2 smaller than the outer diameter D1 of the torsion coil spring 50.

As described above, in this embodiment, the torsion coil spring 50 is twisted and accommodated in the spring accommodating space, so that even if the size of the cup portion 22 is the same, the coil length is longer than the coil length conventionally allowed to be accommodated. A torsion coil spring 50 having a length can be accommodated. Therefore, it is possible to obtain a tensioner having a sufficient output torque.

Next, a second embodiment will be described with reference to FIG. Tensioner 100 in second embodiment
Then, the cup part 22 and the lid part 3 when the arm 30 swings
A damping band 110 is provided in addition to the bushing 32 to improve the frictional force between the ten. FIG. 5 shows the second
It is sectional drawing of the tensioner 100 to which Embodiment of this invention was applied. Note that members common to the first embodiment are denoted by the same reference numerals.

As described above, the torsion coil spring 50
Is accommodated along the inner peripheral surface 225 of the cup bottom side,
A torsion coil spring 5 is provided near the center of the cup portion 22.
0 does not touch. A damping band 110 is provided in a space near the center where the torsion coil spring 50 does not abut.
Is installed.

In the cup portion 22, the bolt engaging portion 22
A damping band installation part 226 is provided on the outer peripheral side from the first. The damping band setting part 226 extends toward the opening of the cup part 22 and has a predetermined height so as not to come into contact with the lid part 310. The damping band 110 is interposed between the damping band setting part 226 and the lid part 310.
The damping band 110 is formed of, for example, a synthetic resin. The damping band 110 is a member that generates a frictional force between the cup portion 22 and the lid portion 310 when the arm 30 swings, and the frictional force generated between the cup portion 22 and the lid portion 310 due to the interposition of the bushing 32. In addition to the above, a friction force is further added. The provision of the damping band 110 gives further rotational resistance to the arm 30 and attenuates the vibration of the drive belt 17.

On the inner peripheral side of the damping band 110, the ring spring 1 for urging the damping band 110 toward the damping band installation portion 226 with a substantially constant pressure.
11 are provided. The shape (not shown) of the ring spring 111 in the longitudinal direction is the same as that of the damping band 110.
Is a shape along the inner circumference.

In the second embodiment, the pivot bolt 23
The cushioning member 241 interposed between the head 232 and the cup bottom surface 224 has an L-shaped cross section. The buffer member 241 is also interposed between the column portion 231 of the pivot bolt 23 and the bolt engaging portion 221. A predetermined gap 25 is formed between the cylindrical portion 231 of the pivot bolt 23 and the cushioning member 241, and the pivot bolt 23 is rotatable in the axial direction of the cylindrical hole 222. In this way, the cushioning member 241 is
By interposing also between the bolt 31 and the bolt engaging portion 221, wear due to collision between the column portion 231 and the bolt engaging portion 221 due to rotation of the pivot bolt 23 is prevented.

In the second embodiment in which the frictional force between the cup portion 22 and the lid portion 310 when the arm 30 swings as described above, the torsion coil spring 50 which cannot be housed in the cup portion 22 under no load condition. Can be accommodated in the cup part 22 by twisting.

[0040]

According to the present invention, it is possible to obtain a tensioner capable of applying a sufficient urging force to the drive belt while reducing the size of the apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a belt system of an automobile engine.

FIG. 2 is a sectional view of a tensioner to which the first embodiment is applied.

FIG. 3 is a front view showing a fixing member.

FIG. 4 is a front view showing a torsion coil spring.

FIG. 5 is a sectional view of a tensioner to which the second embodiment is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Tensioner 20 Fixing member 22 Cup part 23 Pivot bolt 25 First coil support part 26 Second coil support part 30 Arm 40 Pulley 50 Torsion coil spring 310 Lid part 501 One end part 502 Other end part 503 Spiral part

Claims (7)

[Claims] A fixed member having a cup portion having a predetermined inner diameter; an arm swingably attached to the fixed member; an outer diameter larger than the predetermined inner diameter; And a torsion coil spring that is housed in the cup portion by being twisted in a direction to urge the arm in a predetermined direction. 2. The torsion coil spring has one end engaged with a first engagement portion provided in the fixed member, and the other end engaged with a second engagement portion provided in the arm. ,
The relative position between the first engagement portion and the second engagement portion is
2. The method according to claim 1, wherein the torsion coil spring is different when the first engagement portion and the second engagement portion are engaged with each other and when the arm is attached to the fixing member. 3. Thin tensioner as described. 3. The thin tensioner according to claim 1, wherein an axis length of the torsion coil spring is relatively shorter than the outer diameter. 4. The thin tensioner according to claim 1, further comprising at least one friction member interposed between the cup portion and the arm and providing frictional resistance to the swing of the arm. . 5. The friction member is formed of a cylindrical portion and a flange portion projecting from a lower end of the cylindrical portion to an inside of the cup portion and the arm, and has an L-shaped cross section. Item 6. A thin tensioner according to item 4. 6. A first step of twisting a torsion coil spring having an outer diameter larger than the inner diameter of the cup portion to make the outer diameter smaller than the inner diameter, and connecting the twisted torsion coil spring to the cup portion and the arm. 2. A method of assembling a thin tensioner, comprising a second step of interposing between them. 7. A first step of engaging one end of a torsion coil spring having an outer diameter larger than the inner diameter of the cup with the cup, and a second step of engaging the other end of the torsion coil spring with the arm. A third step of twisting the torsion coil spring by rotating the arm to make the outer diameter smaller than the inner diameter; and bringing the arm close to the cup portion to thereby rotate the torsion coil spring. And a fifth step of rotatably fixing the arm to the cup section by compressing the arm into the cup section, and a fifth step of rotatably fixing the arm to the cup section.