JP2009236159A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the torque and to increase the damping effect by increasing damping force even if a bearing bush 31 is not formed from a resin sliding member, in an automatic tensioner which includes: a fixed body 10 having a shaft part 12 and fixed on a fixation side; a turning body 20 having a boss part 22, which is inserted into the shaft part 12 for holding through a bearing bush 31, and having a pushing part 25 for pushing a belt; and a torsion coil spring 40 interposed between the fixed body 10 and the turning body 20 to energize the turning body 20 to the fixed body 10 so that the pushing part 25 is turned in the belt pushing direction. <P>SOLUTION: At least one damping member 50 is provided in a boss part 22 of a turning body 20 so as to be integrally turned, and the outer surface of the damping member 50 in the radial direction can be brought in contact with the inside of a coil part 41 of a torsion coil spring 40 and the inner surface thereof in the radial direction can be brought in contact with the peripheral surface of the shaft part 12 of a fixed body 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention twists a rotating body rotatably supported by a fixed body via a bearing bush and urges it to rotate in the belt pressing direction with a torsion torque of a coil spring, while utilizing a reaction force of the torsion torque. The present invention relates to an auto tensioner that generates a damping force with respect to the rotation of a rotating body, and more particularly, to a countermeasure for achieving both high torque and high damping.

  As this type of auto tensioner, the one described in Patent Document 1 is known.

As shown in FIG. 6, a metal bush is used as the bearing bush 300 interposed between the shaft portion 110 of the fixed body 100 and the boss portion 210 of the rotating body 200. Then, while the rotating body 200 is urged to rotate in the belt pressing direction by the torsion torque of the torsion coil spring 400, the reaction force of the torsional torque is utilized, and the spring support 500 is still boss of the rotating body 200. The rotation of the rotating body 200 is damped by sliding friction generated between the spring support 500 and the boss portion 210 by pressing against the outer peripheral surface of the portion 210. At that time, the torsion coil spring 400 having a high torsional torque is used so that a high damping force can be obtained.
Japanese Patent Laid-Open No. 2005-69356

  By the way, the conventional auto tensioner has less damping effect than the bearing bush 300 using a resin sliding member.

  If the metal bush is changed to a sliding member, the damping can be increased, but the bushing is likely to be worn because of the high torque. As a result, there is a problem that the axis of the rotating body is inclined.

  The present invention has been made in view of such a point, and a main object thereof is an auto tensioner in which a rotating body is rotatably supported by a fixed body via a bearing bush. By providing a new damping member that can effectively use the change in coil diameter of the torsion coil spring between the boss portion of the rotating body, a high damping force can be obtained without using a resin sliding member as a bearing bush. In this way, it is possible to achieve both high torque and high damping.

  In order to achieve the above object, in the present invention, when the coil portion of the torsion coil spring changes in the direction of diameter reduction, the damping member is pressed against the shaft portion of the fixed body by deformation of the coil portion in the direction of diameter reduction. It was made to provide.

  Specifically, in the present invention, a pressing body that has a shaft and has a fixed body that is fixed to the fixed side, a boss that is inserted and held in the shaft, and presses the transmission belt. A rotating body that is rotatably supported by the fixed body at the boss portion, and is interposed between the fixed body and the rotating body, and presses the rotating body against the fixed body. Provided with a torsion coil spring that urges the transmission belt to rotate in the direction of pressing the transmission belt, and a bearing bush interposed between the shaft portion of the fixed body and the boss portion of the rotating body. Auto tensioner is assumed.

  Each of the rotating bodies is pivotally integrated with the boss portion, and the radially outer surface can be inscribed in the coil portion of the torsion coil spring, while the radially inner surface is on the outer peripheral surface of the shaft portion of the fixed body. And at least one damping member capable of sliding contact.

  In the above-described configuration, the torsion coil spring can be configured to rotate and urge the rotating body with a torsion torque in a direction in which the coil portion expands in diameter.

  Further, the damping member is a first damping member, and is disposed so as to be prevented from rotating on the fixed body side between the coil portion of the torsion coil spring and the boss portion of the rotating body, and the torsional torque of the torsion coil spring is counteracted. A second damping member that is pressed against the outer peripheral surface of the boss portion with force may be provided.

  Furthermore, when there are a plurality of damping members, the plurality of damping members may be arranged at equal intervals or unequal intervals in the circumferential direction.

  Further, a through hole that penetrates the boss portion in the radial direction may be provided in the boss portion of the rotating body, and the damping member may be held in the through hole so as to be movable in the radial direction.

  In that case, the damping member has a block portion that extends through the through hole in the radial direction and a holding portion that engages with the boss portion so as to hold the block portion in a state of passing through the through hole. can do.

  As an example of the holding portion, a pair of arm portions that extend from the radially outer end of the block portion to both sides in the circumferential direction and sandwich the boss portion may be mentioned.

  According to the present invention, in the auto tensioner in which the rotating body is rotatably supported by the fixed body via the bearing bush, the coil of the torsion coil spring that urges the rotating body to rotate in the belt pressing direction. When the part is deformed in the direction of reducing the diameter according to the turning direction of the rotating body, a new damping member provided integrally with the rotating body is fixed by using the deformation of the coil part. Since a new damping force can be generated by sliding in contact with the shaft portion of the body, the damping force can be increased without using a resin sliding member as the bearing bush. Both torque and high damping can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of an auto tensioner according to an embodiment of the present invention, and this auto tensioner transmits a part of the output of an automobile engine to a plurality of auxiliary machines via one transmission belt. The belt transmission device having the serpentine layout is used for applying a predetermined tension to the transmission belt.

  The auto tensioner includes a fixed body 10 fixed to an engine as a fixed side, and a rotating body 20 supported by the fixed body 10 so as to be rotatable around a rotation axis P.

  The fixed body 10 includes a bottomed cylindrical cup portion 11 and a shaft portion 12 provided so as to extend along the rotation axis P from the center of the bottom wall portion of the cup portion 11. The tip of the shaft portion 12 protrudes outward from the opening of the cup portion 11. In the vicinity of the bottom wall portion of the peripheral wall portion of the cup portion 11, a fixed-side locking hole 13 that penetrates the peripheral wall portion in the radial direction is provided. Further, in the vicinity of the peripheral wall portion in the bottom wall portion of the cup portion 11, an anti-rotation hole 14 penetrating the bottom wall portion is provided.

  On the other hand, the rotating body 20 includes a bottomed cylindrical cup portion 21 and a boss portion that is provided at the center of the bottom wall portion of the cup portion 21 and is fitted onto the shaft portion 12 of the fixed body 10. 22. The fixed body side portion of the boss portion 22 protrudes outward from the opening of the cup portion 21. Moreover, the outer peripheral surface of the boss | hub part 22 is formed in the cross-sectional taper shape in which a diameter becomes small gradually toward the front end side. Between the boss portion 22 and the shaft portion 12 of the fixed body 10, two metal bushes 31 and 31 for holding the boss portion 22 around the rotation axis P by the shaft portion 12 are pivoted. Thus, the rotating body 20 is supported by the fixed body 10 so as to be rotatable about the rotation axis P. The metal bush 31 has a small damping effect because it has a smaller sliding resistance than a resin sliding member, but unlike the sliding member, there is an advantage that there is less uneven wear associated with higher torque. These metal bushes 31, 31 are respectively disposed in the vicinity of both end portions of the shaft portion 12. Further, a part of the circumferential wall portion of the cup portion 21 in the circumferential direction is formed in the turning-side locking recess 23 in a notched state.

  The tip of the shaft portion 12 of the fixed body 10 protrudes outward in the axial direction from the opening on the opposite side of the boss portion 22 of the rotating body 20 to the fixed body 10. A front plate 32 is attached to prevent the shaft from being removed from the shaft portion 12. Between the front plate 32 and the boss portion 22, a resin-made thrust washer 33 is interposed.

  The rotating body 20 has an arm 24 provided so as to protrude radially outward from the outer periphery of the cup portion 21. A tension pulley 25 as a belt pressing portion is held at the tip of the arm 24 so as to be rotatable around an axis Q parallel to the rotation axis P. Specifically, a bolt hole 26 penetrating in the axial direction is provided at the tip of the arm 24. A shaft portion of a flanged hexagon bolt 27 is inserted into the bolt hole 26, and a nut 28 is screwed to the tip of the shaft portion. A bearing 34 having a plurality of rolling elements between the inner and outer rings is sandwiched between the flange portion of the bolt 27 and the arm portion 24 in the inner ring. The tension pulley 25 is press-fitted and fixed on the outer ring of the bearing 34.

  A torsion coil spring 40 is interposed between the fixed body 10 and the rotating body 20. The torsion coil spring 40 has a left-handed coil portion 41, and a fixed-side tongue 42 and a rotating-side tongue 43 that protrude outward in the radial direction from both ends of the coil portion 41. The fixed-side tongue 42 is locked in the fixed-side locking hole 13 of the fixed body 10 and is restricted from moving in the circumferential direction. The rotation-side tongue 43 is engaged with the rotation-side engagement recess 23 of the rotation body 20 and is restricted from moving in the circumferential direction. The torsion coil spring 40 is interposed in a state where the coil portion 41 is compressed in the axial direction and the coil portion 41 is twisted in the diameter reducing direction. Therefore, the boss portion 22 of the rotating body 20 is pressed against the thrust washer 33 by the axial extension force of the torsion coil spring 40, and the rotating body 20 is deformed by the torsion torque of the torsion coil spring 40. 2 is urged to rotate counterclockwise.

  Between the coil portion 41 of the torsion coil spring 40 and the boss portion 22 of the rotating body 20, a spring support 35 made of a resin sliding material is interposed. The spring support 35 includes a cylindrical portion 35a disposed on the boss portion 22 in an externally fitted state, and an outward flange-like flange portion 35b provided around the fixed body side opening edge of the cylindrical portion 35a. On the surface of the flange portion 35b opposite to the cylindrical portion 35a, a protrusion 35c is provided that fits into the rotation stop hole 14 of the fixed body 10 and prevents the spring support 35 from rotating relative to the fixed body 10. Further, the cylindrical portion 35 a is extremely short compared to the axial length of the boss portion 22, and covers only the end portion of the boss portion 22 on the fixed body 10 side. When the rotating body 20 is rotated, a part of the coil portion 41 in the circumferential direction presses the cylindrical portion 35a of the spring support 35 inward in the radial direction by the reaction force of the torsional torque of the torsion coil spring 40. The cylindrical portion 35 a is pressed against the boss portion 22 of the rotating body 20, so that sliding friction is generated between the inner peripheral surface of the cylindrical portion 35 a and the outer peripheral surface of the boss portion 22. It becomes a part of damping force with respect to rotation. At that time, the portion of the torsion coil spring 40 that presses the spring support 35 is generally the first turn on the fixed tongue 42 side of the coil portion 41 (specifically, approximately 90 in the winding direction of the coil portion 41 from the fixed side tongue 42). The cylindrical portion 35a can be slidably contacted only with the end of the boss portion 22 on the fixed body 10 side, but the cylindrical portion can be slidably contacted with the majority portion of the boss portion 22. Compared with, it is possible to generate a damping force that is inferior.

  In the present embodiment, the boss portion 22 of the rotating body 20 is provided so as to be movable in the radial direction, and the outer surface in the radial direction can be inscribed in the coil portion 41 of the torsion coil spring 40. Two damping members 50, 50 whose inner surface in the direction can slide on the outer peripheral surface of the shaft portion 12 of the fixed body 10 are provided.

  Specifically, the two damping members 50, 50 are arranged in a state of facing each other in the radial direction. The boss portion 22 of the rotating body 20 has two through holes 22a and 22a that penetrate the peripheral wall of the boss portion 22 in the radial direction. For each hole 22a, a pair of engaging surfaces 22b, 22b parallel to each other in the radial direction perpendicular to the extending direction of the through hole 22a is formed. Here, the two engaging surfaces 22b and 22b corresponding to each other between the two through holes 22a and 22a are made common to form a single plane. Each damping member 50 is held in the corresponding through hole 22a so as to be movable in the radial direction.

  Each damping member 50 holds the block portion 51 as a main body portion extending radially through the through-hole 22a and the block portion 51 penetrating the through-hole 22a as shown in FIGS. As described above, a pair of arm portions 52 and 52 are provided as holding portions that engage with the boss portion 22.

  Here, the damping member 50 will be described in detail with reference to FIGS. The block 51 has a substantially rectangular cross section. The end surface on the radially outer side has a circular arc shape with the same radius of curvature as the outer peripheral surface of the boss portion 22 of the rotating body 20, and the end surface on the radially inner side is the end surface of the shaft portion 12 of the fixed body 10. It has a circular arc shape with a radius of curvature substantially the same as the outer peripheral surface.

  On the other hand, the arm portions 52, 52 respectively extend in a circular arc shape in the clockwise direction and the counterclockwise direction from the radially outer end portion of the block portion 51 along the outer peripheral surface of the boss portion 22 of the rotating body 20. Thus, the boss portion 22 is sandwiched between the arm portions 52 and 52. The outer peripheral surface of each arm portion 52 is formed in a circular arc shape with a radius of curvature that is 1/2 of the inner diameter of the coil portion 41 of the torsion coil spring 40. There is contact throughout. The inner peripheral surface of each arm portion 52 has a cross-sectional arc shape with a radius of curvature that is slightly larger than ½ of the outer diameter of the boss portion 22 of the rotating body 20. The gap is formed. In addition, on the inner peripheral side of the end portion of each arm portion 52, a press contact portion 52a that presses in contact with the engagement surface 22b of the corresponding boss portion 22 in a surface contact state is provided. Further, between the end of each arm portion 52 of one damping member 50 and the end of each arm portion 52 of the other damping member 50 corresponding to this end portion, both damping members 50 and 50 are respectively provided. A slight gap is secured so as not to hinder the movement inward in the radial direction.

  Therefore, according to this embodiment, the fixed body 10 which has the axial part 12 and is fixed to the engine side for automobiles, and the boss part inserted and held in the axial part 12 via the metal bushes 31 and 31. 22 and a tension pulley 25 for pressing the transmission belt. The rotating body 20 is rotatably supported by the fixed body 10 at the boss portion 22, and the fixed body 10 and the rotating body 20. In an auto tensioner provided with a torsion coil spring 40 interposed therebetween and biasing the rotating body 20 relative to the fixed body 10 so as to rotate in a direction in which the tension pulley 25 presses the transmission belt. Each of them is provided integrally with the boss portion 22 of the rotating body 20 so that the outer surface in the radial direction can be inscribed in the coil portion 41 of the torsion coil spring 40, while the inner surface in the radial direction is fixed. Since the two damping members 50 and 50 slidably contacted with the outer peripheral surface of the shaft portion 12 of the body 10 are provided, the coil portion 41 of the torsion coil spring 40 is reduced in diameter in accordance with the rotation of the rotating body 20. When changed, the two damping members 50 and 50 that rotate integrally with the rotating body 20 are pressed inward in the radial direction by the coil portion 41 to be brought into sliding contact with the outer peripheral surface of the shaft portion 12 of the fixed body 10. Thus, a new damping force can be generated, so that the damping force can be increased without replacing the metal bush 31 with a resin sliding member, and thus both high torque and high damping can be achieved. be able to.

  In particular, the torsion coil spring 40 is interposed so as to urge the rotating body 20 with a torsional torque in the direction in which the coil portion 41 expands. Since the damping force is generated when the belt rotates in the direction opposite to the belt pressing direction, the increase is gradually absorbed when the belt tension increases, while the transmission belt is quickly pressed to reduce the belt tension when the belt tension decreases. Can be recovered.

  Further, between the coil portion 41 of the torsion coil spring 40 and the boss portion 22 of the rotating body 20, the boss portion 22 is prevented from rotating on the fixed body 10 side by the reaction force of the torsion torque of the torsion coil spring 40. The spring support 35 that generates a damping force by being pressed against the outer peripheral surface of the boss portion 22 is disposed in the vicinity of the fixed body side end portion of the boss portion 22 even though the damping member 50 is newly provided on the boss portion 22. Therefore, the damping force and damping characteristics obtained by the spring support 35 can be substantially maintained.

  Further, since the two damping members 50 are provided and these two damping members 50 are arranged at equal intervals in the circumferential direction, the pressing force of the coil portion 41 applied to each damping member 50 (FIG. 2). (Indicated by white arrows) can be offset each other, and a situation in which a biased load is applied to the torsion coil spring 40 can be avoided.

  Furthermore, a block portion 51 that penetrates the damping member 50 through the through hole 22a of the boss portion 22 so as to be movable in the radial direction, and a pair of arms that extend from the radially outer end of the block portion 51 to both sides in the circumferential direction. Since the damping member 50 can be held in the state assembled to the boss portion 22 by the arm portions 52, 52, the auto tensioner is added in spite of adding a new member. Assembling workability can be maintained well. Moreover, since the pair of arm portions 52 and 52 cover the periphery of the through hole 22a of the boss portion 22, the pair of arm portions 52 and 52 also serves to prevent foreign matter from entering.

  In the above-described embodiment, a pair of holding portions for holding the block portion 51 in a state assembled to the boss portion 22 is provided in the block portion 51 of the damping member 50 so as to hold the boss portion 22 in the radial direction. However, the structure of such a holding portion is not particularly limited, can be designed as appropriate, and is particularly necessary in the assembly work of the auto tensioner. If not, it can be omitted.

  In the above-described embodiment, the cross-sectional shape of the block portion 51 of the damping member 50 is substantially rectangular, and the boss portion 22 is also provided with a substantially rectangular through hole 22a. Can be designed arbitrarily.

  In the above embodiment, the two damping members 50 are used. However, the number of the used members is arbitrary and may be three or more. Conversely, the required damping force is sufficient. If it can be obtained, one may be used.

  In the above embodiment, the two damping members 50, 50 are arranged at rotationally symmetric positions (equally spaced in the circumferential direction) about the rotation axis P. However, two damping members 50 are provided. In the above case, it may be arranged at asymmetric positions (unequally spaced in the circumferential direction) depending on the required damping characteristics.

  Further, in the above-described embodiment, the torsion coil spring 40 is urged to rotate the rotating body 20 with a torsion torque in the direction in which the coil portion 41 expands, but the direction in which the coil portion 41 decreases in diameter. The rotating body 20 may be urged to rotate with a torsional torque. However, in that case, the damping force when the rotating body 20 rotates in the belt pressing direction is increased.

  Furthermore, in the above-described embodiment, the spring support 35 is used together with the damping member 50. However, it can be omitted if unnecessary.

It is a longitudinal section showing the whole auto tensioner composition concerning the embodiment of the present invention. It is the II-II sectional view taken on the line of FIG. It is the front view seen from the axial center side which shows a damping member. It is the top view seen in the axial direction which shows a damping member. It is the VV sectional view taken on the line of FIG. FIG. 2 is a view corresponding to FIG. 1 illustrating an overall configuration of a conventional auto tensioner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fixed body 12 Shaft part 20 Rotating body 22 Boss part 22a Through-hole 25 Tension pulley (pressing part)
31 Metal bush (bearing bush)
35 Spring support (second damping member)
40 Torsion coil spring 41 Coil part 50 Damping member 51 Block part (main part)
52 Arm part (holding part)
P rotation axis (axis)

Claims (8)

A fixed body having a shaft portion and fixed to the fixed side;
A rotating body that has a boss part inserted and held in the shaft part and a pressing part for pressing the transmission belt, and is rotatably supported by the fixed body in the boss part;
A torsion coil spring that is interposed between the fixed body and the rotating body and urges the rotating body toward the direction in which the pressing portion presses the transmission belt with respect to the fixed body;
A bearing bush interposed between the shaft portion of the fixed body and the boss portion of the rotating body;
Each is provided integrally with the boss portion of the rotating body, and the radially outer surface can be inscribed in the coil portion of the torsion coil spring, while the radially inner surface is in sliding contact with the outer peripheral surface of the shaft portion of the fixed body. An auto tensioner comprising at least one possible damping member. The auto tensioner according to claim 1,
The torsion coil spring is characterized in that the rotating body is urged to rotate with a torsional torque in a direction in which the coil portion expands in diameter. The auto tensioner according to claim 1,
The damping member is a first damping member,
A second portion which is disposed between the coil portion of the torsion coil spring and the boss portion of the rotating body so as to be prevented from rotating on the fixed body side and is pressed against the outer peripheral surface of the boss portion by the reaction force of the torsion torque of the torsion coil spring. An auto tensioner comprising a damping member. The auto tensioner according to claim 1,
There are a plurality of damping members,
The auto tensioner, wherein the plurality of damping members are arranged at equal intervals in the circumferential direction. The auto tensioner according to claim 1,
There are a plurality of damping members,
The auto tensioner, wherein the plurality of damping members are arranged at irregular intervals in the circumferential direction. The auto tensioner according to claim 1,
The boss portion of the rotating body has a through hole that penetrates the boss portion in the radial direction,
An auto tensioner, wherein the damping member is fitted into the through hole so as to be movable in the radial direction. The auto tensioner according to claim 6, wherein
The damping member has a main body portion that is inserted into the through hole so as to be movable in the radial direction, and a holding portion that engages with the boss portion so as to hold the main body portion in a state of being inserted into the through hole. An auto tensioner characterized by that. The auto tensioner according to claim 7,
The holding portion of the damping member is composed of a pair of arm portions extending from the radially outer end of the main body portion to both sides in the circumferential direction so as to sandwich the boss portion.

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