JPH04244644A - Auto tensioner - Google Patents

Abstract

PURPOSE:To keep a belt in proper tension at all times, in an auto tensioner which keeps the belt tension constant. CONSTITUTION:A cylindrical part 6 is installed in a pedestal 1 to be attached to an engine block 5. A pulley 10 is supported free of rotation by an arm 8 rotatably supported with the cylindrical part 6 as the center. Resilience of a torsion coil spring 12 is energized to this arm 8, thereby pressing the pulley 10 to a belt. A pressing projection 15 of a friction member 18 assembled into the cylindrical part 6 is installed on the outer circumference of a shaft part 14 installed in the arm 8. This friction member 18 is pressed to an innerdiametral surface of the cylindrical part 6 by means of unidirectional rotation of the projection 15 rotating together with the arm 8, generating a frictional resistance there, and with this frictional resistance, any rocking motion of the pulley in direction of loosening the belt is damped. In addition, at time of rotation in the reverse direction of the projection 15, the friction member 18 is smoothly shifted in the circumferential direction, and the pulley 10 is smoothly rocked in direction of tensing the belt by dint of resilience of the torsion coil spring 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an autotensioner that maintains the tension of a belt constant.

0002

[Prior Art] As an auto tensioner that keeps the tension of a driving belt of an automobile auxiliary device such as an alternator constant, the tensioner shown in FIG.
The one shown in is conventionally known.

[0003] In the auto tensioner, a housing 53 is fixed by tightening a bolt 52 screwed into an engine block 51, and a cylindrical portion 56 provided at one end of an arm 55 is rotatably provided on the outside of a support shaft 54 provided in the housing 53. A pulley 57 is attached to the other end of the arm 55.
is rotatably mounted, and the arm 55 is biased in one direction by a torsion spring 58 incorporated in the housing 53,
A pulley 57 is pressed against a belt (not shown) to tension the belt.

Further, axial holes 59 that open at the rear end surface of the cylindrical portion 56 are provided at equal intervals in the circumferential direction, and each hole 59 has a friction member 60 and a spring that presses the friction member 60 against the bottom surface of the housing 53. 61, and its friction member 6
The vibration of the belt applied to the arm 55 is absorbed by the contact resistance of 0, preventing the arm 55 from excessively swinging and suppressing the vibration of the belt.

[0005]

[Problems to be Solved by the Invention] In the auto tensioner described above, the frictional resistance of the friction member 60 that damps the rotation of the arm 55 is always constant, and the frictional resistance is set to be large enough to withstand the maximum load fluctuation. Since this setting is necessary, the swinging of the arm 55 must be slow in both the belt tension side and slack side.

[0006] For this reason, when the belt suddenly loosens due to engine start-up, etc., the arm 55 attempts to swing in the direction of applying tension to the belt, but due to the above-mentioned frictional resistance, it cannot swing smoothly. The vibration of the belt causes abnormal noise, and the belt does not have proper tension, causing slippage between the belt and the pulleys, resulting in abnormal noise.

[0007] The present invention solves the above-mentioned inconvenience, and enables the pulley that applies tension to the belt to swing smoothly only in the direction that tensions the belt, so that the belt can be maintained at an appropriate tension at all times. The technical challenge is to do so.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the first invention provides a pedestal that is fixed to a base such as an engine block and has a cylindrical portion on the back side of the base. , a rotating body rotatably supported around the axial center of the cylindrical part; It has a pulley that swings around the center, and a biasing member that biases a rotating body in one direction to press the pulley against the belt, and the rotating body has a shaft portion that is coaxially arranged with the cylindrical portion. a protrusion having a first end face extending in the radial direction and a second end face having an angle close to perpendicular to the radial direction is provided on the outer periphery of the shaft part; The structure incorporates a friction member having a cylindrical outer surface along the surface and two engaging surfaces that engage with both end surfaces of the protrusion.

[0009] Furthermore, in the second invention, the first part of the protrusion
A configuration was adopted in which a spring was incorporated between the end face and the opposing face of the friction member.

0010

[Operation] In the first invention, when the tension of the belt guided by the pulley increases and the pulley is pushed by the belt, the rotating member rotates around the axis of the cylindrical portion of the base. At this time, the second end surface of the protrusion provided on the shaft of the rotating member presses one end of the friction member against the inner diameter surface of the cylindrical portion, and the frictional resistance of the pressed portion causes the pulley to move around the axis of the cylindrical portion. Slowly rock in the direction of loosening.

Furthermore, when the belt becomes slack and the rotating member rotates due to the elasticity of the biasing member, and the pulley swings in a direction that tensions the belt, the first end surface of the protrusion presses the other end surface of the friction member in the circumferential direction. do. Therefore, the friction member rotates smoothly along the inner surface of the cylindrical portion, and the pulley quickly swings in a direction that tensions the belt.

[0012] When a spring is incorporated between the first end face and the opposing face of the friction member as in the second invention, even if the cylindrical outer surface of the friction member is worn, the friction member is not pressed toward the second end face. Therefore, it is possible to prevent a gap from being generated between the second end face or the inner diameter surface of the cylindrical part, and it is possible to reliably generate frictional resistance by the rotation of the protrusion.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 8.

1 to 3 show a first embodiment of an autotensioner according to the present invention. This auto tensioner is an auto tensioner for an auxiliary drive belt that drives an auxiliary machine such as an alternator of an automobile, and has a pedestal 1. This pedestal 1 has a bolt insertion hole 2, and a sleeve 4 with a collar is attached to the outside of the bolt 3 inserted into the bolt insertion hole 2.
is provided.

The bolt 3 is screwed into the engine block 5 as a base, and by tightening the bolt 3, the base 1
is fixed to the engine block 5.

A cylindrical portion 6 is provided on the rear side of the pedestal 1 with respect to the engine block 5. In addition, the cylindrical part 6
A spring protection tube 7 is provided on the outside.

An arm 8 as a rotating body provided on the pedestal 1 has one end rotatably supported around the sleeve 4, and a pulley 10 is rotatably supported at the other end of the arm 8 via a rolling bearing 9. freely supported.

A spring protection tube 11 is provided at one end of the arm 8 to face the spring protection tube 7 of the pedestal 1, and a torsion coil spring 12 is incorporated in both spring protection tubes 7 and 11 as a biasing member. One end is locked to the spring protection tube 7 on the pedestal side,
The other end is locked to a spring protection tube 11 on the arm side. The arm 8 is urged in one direction by the elasticity of the torsion coil spring 12, and the pulley 10 is pressed against the belt 13.

Further, a cylindrical shaft portion 14 is formed at one end of the arm 8 and is rotatable around the sleeve 4, and a protrusion 15 is provided on the outer periphery of the shaft portion 14.

As shown in FIG. 2, the protrusion 15 has a first end surface 16 that extends in the radial direction and a second end surface 17 that is approximately perpendicular to the radial direction and has an appropriate angle. A friction member 18 is incorporated between the protrusion 15 and the cylindrical portion 6.

The friction member 18 has a cylindrical outer surface 19 along the inner diameter surface of the cylindrical portion 6, a first engaging surface 20 that engages with the first end surface 16 of the protrusion 15, and a second end surface 17 that engages with the first engaging surface 20. A second engagement surface 21 is formed.

The autotensioner shown in the first embodiment has the above structure, and when the tension of the belt 13 shown in FIG. swing in the direction. At this time, the protrusion 15 rotates in the direction of the arrow in FIG.
presses the second engagement surface 21 of the friction member 18 in the outer radial direction. Therefore, the friction member 18 comes into strong pressure contact with the inner diameter surface of the cylindrical portion 6, and the contact resistance of the friction member 18 increases due to the pressure contact, and the arm 8 slowly swings in the direction of the arrow.

Further, when the tension of the belt 13 becomes weak and the belt 13 starts to loosen, the arm 8 swings in the direction opposite to the arrow direction in FIG. 16 is the first engagement surface 20 of the friction member 18
Press.

Since the first end surface 16 is a surface extending in the radial direction, the first end surface 16 of the friction member 18 is pushed in the circumferential direction, and no pressing force is generated against the inner diameter surface of the cylindrical portion 6, so that the frictional resistance is reduced. Does not increase. Therefore, the friction member 18
4, the pulley 10 quickly follows the slack of the belt 13, and tensions the belt 13 instantly.

As described above, the swinging motion in the direction in which the arm 8 is pushed by the belt 13 is damped by the friction of the friction member 18, while the swinging motion in the direction that applies tension to the belt 13 is not damped. Even if the belt 13 suddenly loosens and tries to separate from the pulley 10, the arm 8 will instantly swing and pull the pulley 10
3 and apply the biasing force of the torsion coil spring 12 to the belt 1.
3, and the belt 13 can be maintained at an appropriate tension at all times.

FIG. 4 shows a second embodiment of the autotensioner according to the invention. In this embodiment, the shaft portion 1
A plurality of protrusions 1 having a first end surface 16 and a second end surface 17 at 4.
5, a friction member 18a is provided opposite each protrusion 15, and a friction pad 22 having a high friction coefficient is attached to the cylindrical outer surface 19a of each friction member 18a. The other configurations are the same as those in the first embodiment, so they are not shown.

Also in this second embodiment, the pulley 10
is pushed by the belt 13, and when the shaft portion 14 rotates together with the arm 8, the protrusion 15 pushes the opposing friction member 18a against the inner cylinder portion 6.
is pressed against the inner surface of the material, creating frictional resistance. On the other hand, when rotating in the opposite direction, the protrusion 15 only pushes the friction member 18a in the circumferential direction, and no frictional resistance is generated, resulting in smooth rotation.

Note that a friction pad may be provided on the inner diameter surface of the cylindrical portion 6.

FIG. 5 shows a third embodiment of an autotensioner according to the present invention. In this embodiment, the shaft portion 1
4, three protrusions 15 are formed at intervals of 120°, and a friction member 18b is provided opposite each protrusion 15, and the first end surface 16 of each protrusion 15 and the friction member opposing this are provided. 18
It has a configuration in which a spring 23 is built in between it and b.

By incorporating the spring 23, the gap between the inner diameter surface of the cylindrical portion 6 or the second end surface 17 of the protrusion 15 caused by wear of the friction member 18b is eliminated, and when the arm 8 is pushed by the belt 13, frictional resistance is eliminated without play. can be generated.

FIGS. 6 to 8 show a fourth embodiment of an autotensioner according to the present invention. The auto tensioner shown in this embodiment is for adjusting the tension of a camshaft driving belt, and has a sleeve 33 provided on the outside of a bolt 32 that fixes a pedestal 31, and a sleeve insertion hole 34 provided at an eccentric position on the outside of this sleeve 33. Eccentric ring 3 as a rotating body formed with
A pulley 37 is rotatably supported on the outside of the eccentric ring 35 via a rolling bearing 36, and the pulley 37 guides the movement of the belt 38.

Further, a tension applying arm 39 is attached to the groove of the eccentric ring 35, and a spring 40 serving as a biasing member connected to the tension applying arm 39 causes the eccentric ring 3 to
5 is applied with a rotational force in one direction, and the pulley 37 is rotated by the belt 38.
is forcing it on.

Further, a shaft portion 42 disposed within the cylindrical portion 41 of the pedestal 31 is provided on the surface of the eccentric ring 35 facing the engine block 5, and a plurality of protrusions 43 provided on the outer periphery of the shaft portion 42 The friction members 44 are opposed to each other. Projection 43
has a first end surface 45 and a second end surface 46 as in the first embodiment, and each end surface 45, 46 faces the first engagement surface 47 and second engagement surface 48 of the friction member 44. There is. Reference numeral 49 indicates a spring incorporated between the first end surface 45 and the first engagement surface 47.

In the autotensioner according to the fourth embodiment, when the pulley 37 is pushed by the belt 38, the eccentric ring 35 rotates about the bolt 32. At this time, the protrusion 43 rotates in the direction of the arrow in FIG.
4 is pressed against the inner diameter surface of the cylindrical portion 41 to generate frictional resistance, and the rotation of the eccentric ring 35 is damped by the frictional resistance.

On the other hand, when the belt 38 becomes slack and the eccentric ring 35 rotates due to the elasticity of the spring 40, the protrusion 43 presses the frictional resistance 44 in the circumferential direction. Therefore, the frictional resistance does not increase, and the eccentric ring 35 rotates smoothly, pressing the pulley 37 against the belt 38 and tensioning the belt 38.

[0036]

As described above, in the auto tensioner according to the present invention, when the pulley is pushed by the belt, frictional resistance is applied to the rotary body supporting the pulley to damp the swing of the pulley, and the pulley is pushed by the belt. The belt is swung smoothly in the direction of tensioning it without creating any frictional resistance, so even if the belt tension fluctuates rapidly, the pulley can be kept in close contact with the belt. The tension of the belt can be maintained at an appropriate tension at all times.

Furthermore, since a spring is installed between the first end surface of the protrusion and the facing surface of the friction member, and the spring presses the friction member in the circumferential direction, even if the cylindrical outer surface of the friction member is worn out, , the inner diameter surface of the cylindrical portion or the second
There is no gap between the protrusion and the end face, and the rotation of the protrusion allows the friction member to be reliably brought into pressure contact with the inner diameter surface of the cylindrical part.

[Brief explanation of the drawing]

[Fig. 1] A longitudinal sectional front view showing a first embodiment of an autotensioner according to the present invention.

[Fig. 2] Cross-sectional view taken along line II-II in Fig. 1

[Figure 3] Side view of the same as above

[Fig. 4] A sectional view showing a second embodiment of the auto tensioner as above.

[Fig. 5] A cross-sectional view showing a third embodiment of the above autotensioner.

[Fig. 6] A longitudinal sectional front view showing a fourth embodiment of the auto tensioner as above.

[Figure 7] Side view of the same as above

[Fig. 8] Cross-sectional view taken along line VIII-VIII in Fig. 6

[
Figure 9: Cross-sectional view showing a conventional auto tensioner

[Explanation of symbols]

1 Pedestal 5 Engine block 6, 41 Cylindrical part 8 Arm 10, 37 Pulley 12 Torsion coil spring 14, 42 Shaft part 15, 43 Projection part 16, 45 First end surface 17, 46 Second end surface 18, 18a, 18b, 44 Friction Members 19, 19a
Cylindrical outer surface 20, 45 First engagement surface 21, 46 Second engagement surface

Claims (2)

[Claims] 1. A pedestal fixed to a base such as an engine block and provided with a cylindrical part on the back side of the base; a rotating body supported rotatably about the axis of the cylindrical part; A pulley is rotatably supported by the rotating body and swings around the axis of the cylindrical part when the rotating body rotates about the axis of the cylindrical part, and a pulley that biases the rotating body in one direction. a biasing member that presses the pulley against the belt; the rotating body is provided with a shaft portion disposed coaxially with the cylindrical portion; the shaft portion has a first end surface extending in the radial direction; and a second end surface having an angle close to perpendicular to the protrusion,
An auto tensioner incorporating a friction member inside the cylindrical portion, the friction member having a cylindrical outer surface along the inner diameter surface of the cylindrical portion, and two engaging surfaces that engage with both end surfaces of the protrusion. 2. The autotensioner according to claim 1, wherein a spring is incorporated between the first end surface of the protrusion and the opposing surface of the friction member.