JP2009236158A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize an automatic tensioner by displacing a bearing part 40 in the axial direction relative to a torsion coil spring 50, restricting malfunction due to inclination of a turning body 20, to reduce the diameter of the torsion coil spring 50 without hindering balance between the torsional torque reaction force Fs and the belt reaction force Fb respectively applying to the turning body 20 inside the bearing part 40, in regard to an automatic tensioner which generates damping force to turns of the turning body 20 by energizing the turning body 20, which is supported by a fixed body 10 through a bearing part 40 freely to turn around the shaft center P, in the belt pushing direction, in which a belt pushing part 29 pushes a transmission belt B, with the torsional torque of the torsion coil spring 50, and on the other hand, by pushing a damping member 60 to the turning body 20 with reaction force Fs of the torsional torque so as to generate damping force to turns of the turning body 20. <P>SOLUTION: A torsion coil spring 50 is arranged by displacing in the axial direction relative to a bearing part 40, and a belt pushing part 29 is arranged on a side opposite to the torsion coil spring 50 in the axial direction relative to the bearing part 40. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is an auto that presses a power transmission belt such as an auxiliary drive belt of an automobile engine by a torsion torque of a torsion coil spring, and generates a damping force for a belt pressing operation by utilizing a reaction force of the torsion torque. Regarding tensioners, in particular, measures for reducing the diameter.

  As a conventional auto tensioner, for example, one described in Patent Document 1 is known.

  In this case, as shown in FIG. 3, a rotating body 200 supported by a fixed body 100 so as to be rotatable around an axis P via a bearing portion 400 is applied to a belt pressing direction with a torsion torque of a torsion coil spring 500. Thus, the transmission belt B is pressed by the belt pressing portion 290 to apply tension to the transmission belt B. At the same time, the damping member 600 is pressed against the rotating body 200 with the reaction force Fs of the torsional torque, thereby generating a damping force with respect to the rotation of the rotating body 200.

  Specifically, a damping member 600 is disposed between the coil portion 510 of the torsion coil spring 500 and a portion of the rotating body 200 located radially inward of the coil portion 510, and the torsion coil spring 500 A part of the coil portion 510 in the circumferential direction presses the damping member 600 against the portion of the rotating body 200 with a reaction force Fs of torsional torque, and between the damping member 600 and the rotating body 200 as the rotating body 200 rotates. Is used as a damping force for the rotation of the rotating body 200.

The main forces acting on the rotating body 200 in the direction intersecting the axis P include the belt reaction force Fb acting via the belt pressing portion 290 in addition to the reaction force Fs of the torsion torque. If the balance between the two forces Fs and Fb is not good, the rotating body 200 is inclined with respect to the axis P. Thus, in the above-mentioned Patent Document 1, the axial position of the point of application Ab of the belt reaction force Fb with respect to the rotating body 200 is located in the bearing portion 400, and thus, the reaction force Fs of the torsion torque. Combined with the fact that the position of the acting point As in the axial direction is located in the bearing portion 400, the reaction force Fs of the torsion torque and the belt reaction force Fb are balanced in the bearing portion 400.
Japanese Patent Laid-Open No. 3-20146 (pages 4-5, FIGS. 1-2)

  However, the conventional autotensioner has a drawback in that since the bearing portion 400 exists in the coil portion 510 of the torsion coil spring 500, the bearing portion 400 becomes an obstacle and it is difficult to reduce the diameter.

  To cope with this, it is conceivable to shift the bearing 400 from the torsion coil spring 500 in the axial direction. In this case, the action point As of the reaction force Fs of the torsion torque is shifted from the bearing 400 in the axial direction. For this reason, the balance between the reaction force Fs of the torsional torque and the belt reaction force Fb in the bearing portion 400 may be impaired.

  The present invention has been made in view of such various points, and its main object is to use a torsional torque of a torsion coil spring to rotate a rotating body supported by a fixed body so as to be rotatable about a shaft center through a bearing portion. Accordingly, the transmission belt is pressed in the belt pressing direction to press the transmission belt to apply tension to the transmission belt, and the damping member is pressed against the rotating body with the reaction force of the torsional torque. In an auto tensioner that generates a damping force with respect to the rotation of the moving body, the bearing portion is adjusted without impairing the balance between the reaction force of the torsional torque of the torsion coil spring and the belt reaction force acting on the rotation body. It is possible to displace the torsion coil spring in the axial direction, thereby reducing the diameter of the torsion coil spring and suppressing the occurrence of problems caused by the tilt of the rotating body. It is to be able to contribute to the miniaturization of Nshona.

  In order to achieve the above object, according to the present invention, the torsion coil spring is not only displaced in the axial direction with respect to the bearing portion but also displaced with respect to the belt pressing portion. It was made to arrange on the opposite side to the torsion coil spring in the direction.

  Specifically, in the present invention, a fixed body fixed to the fixed side and a belt pressing portion are provided, and the belt pressing portion presses the belt via the bearing portion around the axis in the belt pressing direction. A rotating body that is rotatably supported by the fixed body, and a torsion coil that is interposed between the fixed body and the rotating body, and biases the rotating body in the belt pressing direction with a torsion torque against the fixed body. Between the spring and the coil portion of the torsion coil spring and the rotating body, and is arranged in a state of being fixed to the fixed body in a non-rotatable manner, and to the rotating body by the reaction force of the torsional torque of the torsion coil spring. An auto tensioner having a damping member pressed so as to be slidable is assumed.

  And the said torsion coil spring and the said belt press part shall be arrange | positioned at the axial direction both sides of the said bearing part, respectively.

  In the above configuration, when the fixed body has a shaft hole and the rotating body has a shaft portion that passes through the shaft hole of the fixed body, the bearing portion is connected to the shaft hole of the fixed body and the rotating shaft. It can be set between the shaft part of the moving body.

  Further, when the coil portion of the torsion coil spring is loosely fitted on the shaft portion of the rotating body, the damping member is disposed between the coil portion of the torsion coil spring and the shaft portion of the rotating body. be able to. In this case, the torsion coil spring urges the rotating body to rotate in the belt pressing direction with a torsional torque in the direction in which the coil portion expands, while the damping member has a reaction force in the direction in which the coil portion decreases in diameter. Is pressed against the shaft portion of the rotating body.

  The torsion coil spring fixed side tongue (tang locked to the fixed body) may be arranged closer to the bearing portion than the rotating side tongue (tang locked to the rotating body) in the axial direction. It is also possible to press the damping member against the shaft portion of the rotating body with a reaction force of torsional torque at a portion of the coil portion end portion approximately 90 ° in the winding direction of the coil portion from the fixed side tongue of the torsion coil spring.

  Furthermore, the axial position where the resultant force of the reaction force of the torsional torque of the torsion coil spring acting on the rotating body and the belt reaction force acting on the rotating body via the belt pressing portion acts can be within the bearing portion. .

  Further, the angle α between the direction in which the reaction force of the torsion torque acts on the rotating body when viewed in the axial direction and the direction in which the belt reaction force acts on the rotating body is within 30 ° (α ≦ 30 °). It is preferable that

  Furthermore, when the fixed body has an attachment portion for fixing the fixed body to the fixed side, the attachment portion can be disposed at the same axial position as the bearing portion.

  According to the present invention, the rotating body rotatably supported by the fixed body via the bearing portion is urged to rotate in the belt pressing direction by the torsion torque of the torsion coil spring, while the damping force is damped by the reaction force of the torsion torque. In an auto tensioner that presses a member against a rotating body to generate a damping force against the rotation of the rotating body, the balance between the reaction force of the torsional torque of the torsion coil spring and the belt reaction force acting on the rotating body is impaired. Therefore, the bearing portion can be displaced in the axial direction with respect to the torsion coil spring, and thus the torsion coil spring is reduced in diameter while contributing to downsizing of the auto tensioner while suppressing the occurrence of problems due to the tilt of the rotating body. be able to.

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

  FIG. 1 shows the overall configuration of an auto tensioner according to an embodiment of the present invention, and this auto tensioner transfers a part of the output torque of an automobile engine to a plurality of auxiliary machines via a single transmission belt B. It is used to apply a predetermined tension to the transmission belt B in a belt-type accessory driving device having a serpentine layout.

  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 housing portion 11 and a mounting piece 12 provided on the outer periphery of the bottom wall of the housing portion 11 so as to protrude outward in the radial direction. The attachment piece 12 is provided with an attachment hole 13 penetrating the attachment piece 12, and a fixed body is fixed by screwing a bolt inserted into the attachment hole 13 into the engine. A shaft hole 14 penetrating the bottom wall is provided in the center of the bottom wall of the bottomed cylindrical portion. A slit-like locking hole 15 is formed in a part of the peripheral wall of the housing portion 11 in the circumferential direction and extends from the position that penetrates the peripheral wall in the radial direction and contacts the bottom wall to the position near the opening.

  On the other hand, the rotating body 20 includes a bottomed cylindrical housing portion 21, a shaft portion 22 erected at the center of the bottom wall of the housing portion 21, and an outward flange provided at the tip of the shaft portion 22. A flange portion 23, an arm portion 24 provided on the outer periphery of the flange portion 23 so as to protrude radially outward, and a pulley holding portion 25 provided at the tip of the arm portion 24. . The housing part 21 is disposed so that the openings of the housing part 11 of the fixed body 10 face each other. The shaft portion 22 passes through the shaft hole 14 of the fixed body 10. The flange portion 23 substantially covers the outer surface of the bottom wall of the housing portion 11 of the fixed body 10. Bolt holes 26 extending in a direction parallel to the shaft portion 22 are formed in the pulley holding portion 25. The outer periphery on the front end side of the pulley holding portion 25 has a small diameter, and a bearing 27 is fitted on the small diameter portion on the inner ring. The inner ring is attached to the pulley holding portion 25 by a flange portion of a flanged bolt 28 screwed into the bolt hole 26. On the outer ring of the bearing 27, a pulley 29 as a belt pressing portion is externally fitted integrally with the belt 27. The pulley 29 comes into contact with the transmission belt B and rotates around the pulley axis Q while the transmission belt B is rotating. Is to be pressed. In addition, a locking hole 30 that penetrates the peripheral wall in the radial direction is formed in a part of the peripheral wall of the housing portion 21 in the peripheral direction and in the vicinity of the bottom wall.

  A bearing bush 40 is interposed between the shaft hole 14 of the fixed body 10 and the shaft portion 22 of the rotating body 20, and the rotating body 20 is attached to the fixed body 10 via the bearing bush 40. It is supported so as to be rotatable about a rotation axis P. That is, in this embodiment, the bearing bush 40 constitutes a bearing portion in the present invention, and the pulley 29 is disposed on one axial side of the bearing bush 40 (the right side in FIG. 1). . Further, a thrust washer 41 made of a sliding material is interposed between the housing part 11 of the fixed body 10 and the flange part 23 of the rotating body 20.

  In this embodiment, the rotating body 20 is rotated about the rotation axis P toward the fixed body 10 in the direction in which the pulley 29 presses the transmission belt B (counterclockwise as viewed from the right side in FIG. 1). A torsion coil spring 50 that is constantly biased so as to rotate is disposed on the side opposite to the pulley 29 in the axial direction with respect to the bearing bush 40 (the left side in the figure).

  Specifically, the torsion coil spring 50 is accommodated between the housing part 11 of the fixed body 10 and the housing part 21 of the rotating body 20, and a right-handed coil part 51 and one end of the coil part 51. From the other end of the coil portion 51, there is a fixed-side tongue 52 that protrudes outward in the radial direction, and a rotation-side tongue 53 that protrudes outward in the radial direction. The coil portion 51 is loosely inserted into the shaft portion 22 of the rotating body 20, and the fixed-side tongue 52 is locked in a state in which movement in the circumferential direction is restricted by the locking hole 15 of the fixed body 10, The rotation-side tongue 53 is similarly locked to the locking hole 30 of the rotating body 20 in a state where movement in the circumferential direction is restricted.

  Further, the torsion coil spring 50 is interposed between the fixed body 10 and the rotating body 20 in a state where the coil part 51 is twisted in the direction in which the diameter of the coil part 51 is reduced. The rotating body 20 is urged to rotate with torsional torque. Further, the torsion coil spring 50 is interposed in a state where the coil portion 51 is compressed in the axial direction, whereby the thrust washer 41 is formed between the housing portion 11 of the fixed body 10 and the rotating body 20. It is in a state of being pinched between the portion 23.

  A damping member 60 is interposed between the coil portion 51 of the torsion coil spring 50 and the shaft portion 22 of the rotating body 20. The damping member 60 is provided on a cylindrical damping portion 61 that is fitted on the shaft portion 22 of the rotating body 20 and can be slidably contacted with the shaft portion 22, and at one opening edge of the damping portion 61. And a flange portion 62 having an outward flange shape. The axial dimension of the damping part 61 is substantially the same as the axial dimension of one turn of the coil part 51 of the torsion coil spring 50. The flange portion 62 is disposed between the end portion of the coil portion 51 on the fixed side tongue 52 side and the bottom wall of the housing portion 11 of the fixed body 10, and is sandwiched between the two by the compressive force of the coil portion 51. Thus, the damping member 60 is fixed to the fixed body 10 so as not to rotate.

  Further, as shown in FIG. 2, the torsion coil spring 50 acts on the pulley 29 when the pulley 29 is in contact with the transmission belt B and applies a predetermined tension to the transmission belt B. A portion of the end portion of the coil portion 51 that is separated from the fixed side tongue 52 in the winding direction of the coil portion 51 by about 90 ° from the fixed side tongue 52 causes the damping portion 61 of the damping member 60 with the reaction force Fs of torsion torque. The direction of pressing against the shaft portion 22 of the rotating body 20 is provided so as to be substantially the same when viewed in the axial direction (the angle α between the two directions in the axial direction is α ≦ 30 °).

  Here, the operation of the auto tensioner configured as described above will be described. Note that the mounting angle (rotational position angle about the rotation axis P) when the auto tensioner is mounted on the automobile engine is such that the pulley 29 presses the transmission belt B and applies a predetermined tension to the transmission belt B. In the applied state, the direction of the belt reaction force Fb applied to the pulley 29 and the protruding direction of the arm portion 24 are determined so as to be substantially orthogonal when viewed in the axial direction.

  When the tension of the transmission belt B decreases with the operation of the automobile engine, in the auto tensioner, the rotating body 20 rotates in the belt pressing direction by the torsional torque of the torsion coil spring 50. On the other hand, when the tension of the transmission belt B increases, the belt reaction force Fb causes the rotating body 20 to rotate in the direction opposite to the belt pressing direction via the pulley 29, thereby causing the belt tension. Therefore, the tension of the transmission belt B is kept substantially constant.

  Thus, when the rotating body 20 rotates according to the tension fluctuation of the transmission belt B, the damping member 60 is applied to the shaft portion 22 of the rotating body 20 with the reaction force Fs of the torsion torque of the torsion coil spring 50. Is pressed, sliding friction is generated between the damping member 60 and the shaft portion 22 as the rotating body 20 rotates, and thereby the rotation of the rotating body 20 is damped.

  At that time, when the rotating body 20 rotates in the belt pressing direction, that is, when the belt tension decreases, the torsion torque of the torsion coil spring 50 changes in a decreasing direction, so that the reaction force Fs also decreases. Therefore, the damping force with respect to the rotation of the rotating body 20 is reduced. On the other hand, when the rotating body 20 rotates in the direction opposite to the belt pressing direction, that is, when the belt tension increases, the torsional torque of the torsion coil spring 50 changes so that the reaction force Fs also changes. Therefore, the damping force for the rotation of the rotating body 20 increases.

  As a result, when the belt tension decreases, the auto tensioner quickly presses the transmission belt B to suppress the decrease in belt tension. On the other hand, when the belt tension increases, the auto tensioner gently absorbs the increase in the belt reaction force Fb. To prevent the belt tension from increasing. By doing so, flapping of the transmission belt B due to tension fluctuations is avoided, thereby preventing slippage of the transmission belt B with respect to the accessory pulley, ensuring torque transmission, and the life of the transmission belt B. Will be prevented from being shortened.

  By the way, the main force acting on the rotating body 20 during the above operation is the belt reaction force Fb transmitted through the pulley 29 and the reaction force Fs of torsion torque transmitted through the damping member 60. In the bearing bush 40, the resultant force F (= Fb + Fs) of these two forces Fb and Fs is supported. Therefore, when the axial position A on which the resultant force F acts is deviated from the bearing bush 40, the rotating body 20 is inclined with respect to the rotating axis P.

  On the other hand, in the present embodiment, the pulley 29 and the torsion coil spring 50 are respectively disposed on both sides in the axial direction of the bearing bush 40, and the axial position Ab on which the belt reaction force Fb acts and the reaction force of the torsion torque. Since there is a bearing bush 40 between the axial position As where Fs acts, compared to the case where there are two axial positions Ab and As on either side of the axial direction of the bearing bush 40, The axial position A where the resultant force F acts is likely to be accommodated in the bearing bush 40. Here, when the respective axial dimensions between the two axial positions Ab and As and the axial position A are Lb and Ls, respectively, between the dimensions Lb and Ls and the two reaction forces Fb and Fs. Has a relationship of Lb × Fb = Ls × Fs.

  Further, in the present embodiment, the fixed-side tongue 52 is located closer to the bearing bush 40 than the rotation-side tongue 53 (the right side in FIGS. 1 and 2), so the rotation-side tongue 53 is fixed. Compared to the case closer to the bearing bush 40 than the side tongue 52, the axial dimension from the bearing bush 40 to the axial position As where the reaction force Fs of the torsion torque acts can be shortened. As a result, the axial position A where the resultant force F acts is easily accommodated in the bearing bush 40.

  Therefore, according to this embodiment, the rotating body 20 supported by the fixed body 10 via the bearing bush 40 so as to be rotatable around the rotation axis P is rotated in the belt pressing direction by the torsion torque of the torsion coil spring 50. In the auto tensioner that is urged to move, the damping member 60 is pressed against the shaft portion 22 of the rotating body 20 by the reaction force Fs of the torsion torque to generate a damping force for the rotation of the rotating body 20. The bearing bush 40 is pivoted with respect to the coil portion 51 of the torsion coil spring 50 without impairing the balance in the bearing bush 40 of the torsion torque reaction force Fs and the belt reaction force Fb of the torsion coil spring 50 acting respectively on the shaft 20. Therefore, the torsion coil spring 50 can be reduced in diameter while suppressing the occurrence of problems due to the inclination of the rotating body 20 and reducing the diameter. It can contribute to miniaturization of Totenshona.

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 a side view which cuts off one part and shows the whole structure of the conventional auto tensioner.

Explanation of symbols

10 Fixed body 12 Mounting piece (mounting part)
14 Shaft hole 20 Rotating body 22 Shaft portion 29 Pulley (belt pressing portion)
40 Bearing bush (bearing part)
50 Torsion coil spring 51 Coil portion 52 Fixed side tongue 53 Rotation side tongue 60 Damping member P Rotation axis (axial center)
B Transmission belt Fs Reaction force of torsional torque Fb Belt reaction force F Combined force of reaction force of torsional torque and belt reaction force

Claims (8)

A fixed body fixed to the fixed side;
A rotating body having a belt pressing portion and supported by the fixed body so as to be rotatable around an axis in a belt pressing direction in which the belt pressing portion presses the belt via a bearing portion;
A torsion coil spring that is interposed between the fixed body and the rotating body, and biases the rotating body in the belt pressing direction with a torsion torque against the fixed body;
Between the coil portion of the torsion coil spring and the rotating body, it is arranged in a state of being fixed to the fixed body so as not to be able to rotate, and is slidably pressed against the rotating body by the reaction force of the torsion torque of the torsion coil spring. An auto tensioner provided with a damping member,
The torsion coil spring and the belt pressing portion are respectively disposed on both axial sides of the bearing portion. The auto tensioner according to claim 1,
The fixed body has a shaft hole,
The rotating body has a shaft portion that penetrates the shaft hole of the fixed body,
The auto tensioner, wherein the bearing portion is set between the shaft hole of the fixed body and the shaft portion of the rotating body. The auto tensioner according to claim 2,
The coil portion of the torsion coil spring is loosely fitted on the shaft portion of the rotating body,
The damping member is interposed between the coil portion of the torsion coil spring and the shaft portion of the rotating body,
The torsion coil spring urges the rotating body to rotate in the belt pressing direction with a torsional torque in the direction in which the coil portion expands, while the damping member moves to the rotating body in a reaction force in the direction in which the coil portion decreases in diameter. An auto tensioner is provided so as to be pressed against the shaft portion of the. The auto tensioner according to claim 3,
The torsion coil spring has a fixed side tongue that is locked to the fixed body, and a rotating side tongue that is locked to the rotating body,
The auto-tensioner according to claim 1, wherein the fixed-side tongue is disposed closer to the bearing portion side than the rotating-side tongue in the axial direction. The auto tensioner according to claim 3,
The portion of the coil end portion, which is approximately 90 ° from the fixed side tongue of the torsion coil spring in the winding direction of the coil portion, is configured to press the damping member against the shaft portion of the rotating body with a reaction force of torsion torque. Auto tensioner characterized by. The auto tensioner according to claim 1,
The axial position where the resultant force of the reaction force of the torsional torque of the torsion coil spring acting on the rotating body via the damping member and the belt reaction force acting on the rotating body via the belt pressing portion is within the bearing portion. An auto tensioner characterized by that. The auto tensioner according to claim 6, wherein
An auto tensioner characterized in that an angle between a direction in which a reaction force of a torsion torque acts on a rotating body and a direction in which a belt reaction force acts on the rotating body is within 30 ° when viewed in the axial direction. The auto tensioner according to claim 6, wherein
The fixed body has an attachment portion for fixing the fixed body to the fixed side,
The auto tensioner, wherein the mounting portion is disposed at the same axial position as the bearing portion.

Images