JP2015108394A - Auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auto tensioner having an excellent damping characteristic.SOLUTION: An auto tensioner 1 includes: a shaft 3; an arm part 5 rotatably attached to the shaft 3; a pulley 7 provided on the arm part 5; an elastic member 8 connecting the arm part 5 to an engine block; energization means 11 connected to the shaft 3 and energizing the arm part 5 in the axial direction of the shaft 3; and a cam 9 provided on any seat surface side of the energization means 11 subjected to stroke variation in a thrust direction with rotation of the arm part 5.

Description

  The technology disclosed in the present specification relates to an auto tensioner used for a vehicle or the like.

  In a belt transmission device for driving an engine accessory such as an automobile, an auto tensioner for adjusting the tension of the belt is used.

  FIG. 5 is a cross-sectional view showing a conventional auto tensioner described in Patent Document 1. As shown in FIG. As shown in the figure, the conventional auto tensioner is provided with a sliding plate 115 that is pivotally integrated with the rotating member 102 and a rotating plate 115 that is pivotally integrated with the fixed member 101, and the sliding plate 115 is disposed on both sides thereof. And a clamping means 116 capable of sliding relative to the sliding member 115 when the turning member 101 is rotated. The auto tensioner applies a predetermined tension to the belt wound around the pulley 108 of the rotating member 101.

Japanese Patent Laid-Open No. 07-113449

  However, as the engine rotation fluctuation and the load on the auxiliary machine increase in recent years, further improvement in damping characteristics is desired for the auto tensioner. In the conventional auto tensioner, the rotating member 101 with the arm portion protruding is provided. However, since the damping characteristic is obtained by the spring included in the clamping means 116 and its sliding, the unidirectional damping is performed. It is difficult to have characteristics.

  An object of the present invention is to provide an auto tensioner having excellent damping characteristics.

  An auto tensioner disclosed in the present specification includes a shaft, an arm portion rotatably attached to the shaft, a pulley provided on the arm portion, and an elastic member that connects the arm portion to an engine block. A biasing means that is compressed and fastened to the shaft, and biases the arm portion in the axial direction of the shaft, and is provided on one of the seating surfaces of the biasing means, and follows the rotation of the arm portion. And a cam whose stroke changes in the thrust direction.

  According to the auto tensioner disclosed in the present specification, since the cam is provided on either seating surface side of the urging means, excellent damping characteristics can be realized.

FIG. 1 is a diagram showing an auto tensioner according to an embodiment of the present invention. 2A is a cross-sectional view taken along the line IIa-IIa of the auto tensioner shown in FIG. 1 in a state where the cam is sleeping, and FIG. 2B is a cross-sectional view showing the auto tensioner in a state where the cam is raised. is there. FIG. 3 is a diagram showing an auto tensioner and a belt driving device according to the embodiment of the present invention. FIG. 4 is a diagram illustrating the relationship between the swing angle of the arm portion and the torque value. FIG. 5 is a cross-sectional view showing a conventional auto tensioner described in Patent Document 1. As shown in FIG.

  FIG. 1 is a diagram showing an auto tensioner according to an embodiment of the present invention. 2A is a cross-sectional view taken along the line IIa-IIa (see FIG. 1) of the auto tensioner according to the present embodiment in a state where the cam is sleeping, and FIG. 2B is a view showing the auto tensioner in a state where the cam is raised. It is sectional drawing which shows a tensioner. Here, “the state where the cam is raised” refers to a state where the axial direction of the pivot shaft 3 and the major axis direction of the cam 9 substantially coincide.

  As shown in FIGS. 1, 2A, and 2B, an auto tensioner 1 according to this embodiment includes a pivot shaft (shaft) 3, an arm portion 5 rotatably attached to the pivot shaft 3, and an arm. A pulley 7 provided on the portion 5, an elastic member (not shown) such as a coil spring that connects the arm portion 5 to the engine block, and an axial direction (thrust direction) of the pivot shaft 3 that is compression-fastened to the pivot shaft 3 ) Is provided with a biasing means 11 for biasing the arm portion 5, and a cam 9 which is provided on any seating surface side of the biasing means 11 and changes the stroke in the thrust direction following the rotation of the arm portion 5. ing.

  The biasing means 11 may be a known spring, but a disc spring is particularly preferable because it can be made compact.

  A bush 17 is attached to the outer peripheral surface of the pivot shaft 3, and the arm portion 5 is attached to the outside of the bush 17. Moreover, in the auto tensioner 1 of this embodiment, the cam 9 is arrange | positioned under the biasing means 11 in Fig.2 (a).

  A friction disk 14 is disposed between the urging means 11 and the arm portion 5, and a washer 13 is sandwiched between the urging means 11 and the friction disk 14. A front plate 15 is disposed on the biasing means 11. A friction disk 18 is disposed between the arm portion 5 and the cam 9. With this configuration, the arm portion 5 swings about the pivot shaft 3 as a rotation center, and swings in the axial direction of the pivot shaft 3 by receiving the thrust force of the biasing means 11.

  The cam 9 having a long axis and a short axis is connected to an elastic member 19 such as a coil spring, and becomes a sleeping state or a rising state in accordance with the rotation of the arm portion 5. Specifically, the friction disk 18 also rotates with the rotation of the arm unit 5. Then, frictional resistance is generated at the contact portion between the friction disk 18 and the cam 9 in the lying state, and the cam 9 rises in the direction of the arrow due to this friction. At this time, the elastic member 19 applies a force in the direction in which the elastic member 19 extends to the cam 9 to assist the cam 9 in rising.

  Then, as shown in FIGS. 2A and 2B, when the cam 9 rises from the sleeping state, the urging means 11 is compressed via the arm. Then, the sliding resistance between the arm portion 5 and the friction disks 14 and 18 is increased, and as a result, the damping characteristic in the axial direction of the pivot shaft 3 can be obtained.

  FIG. 3 is a diagram illustrating the auto tensioner and the belt driving device of the present embodiment. The auto tensioner 1 transmits the torque generated by the elastic member 8 such as a coil spring to the accessory driving belt 21 via the pulley 7. The belt drive device includes the drive pulley 4 and the pulleys 2a and 2b, but the number and size of the pulleys are not limited to the example of FIG.

  FIG. 4 is a diagram illustrating the relationship between the swing angle of the arm portion and the torque value. The horizontal axis represents the swing angle (°) of the arm portion 5, and the vertical axis represents the torque (N · m) around the pivot shaft 3. The characteristic of the auto tensioner 1 of this embodiment is shown by a solid line, and the characteristic of a conventional auto tensioner without a cam is shown by a broken line.

  In the conventional auto tensioner, when the arm portion rotates so as to press the elastic member (point A ′), the torque increases and the torque decreases as the swing angle decreases. On the other hand, when the arm portion 5 is rotated so that the elastic member 8 is extended (point B ′), the torque becomes low and the torque becomes small as the swing angle becomes small. Here, the torque C ′ is obtained by (A ′ + B ′) / 2, and the damping value is obtained by 100 × (A′−B ′) / 2C ′.

  On the other hand, in the auto tensioner 1 of the present embodiment, when the arm portion 5 rotates so as to push the elastic member 8 (point A), the cam 9 rises and compresses the biasing means 11, so that the torque is Significantly larger than conventional auto tensioners. The torque tends to decrease as the swing angle of the arm portion 5 decreases, as in the conventional auto tensioner. On the other hand, when the arm portion 5 rotates so that the elastic member 8 is extended (point B), the cam 9 is in a sleeping state, and the torque is slightly smaller than that of the conventional auto tensioner. The torque decreases as the swing angle of the arm portion 5 decreases, as in the conventional auto tensioner. Torque C is obtained by (A + B) / 2, and a damping value is obtained by 100 × (A−B) / 2C.

  In the conventional auto tensioner, since the thrust force of the urging means of the clamping means is constant regardless of the swinging amount of the arm portion, the damping characteristic is always constant. On the other hand, in the auto tensioner 1 of this embodiment, since the cam 9 is provided, it is possible to increase only the damping value for swinging in one direction (the axial direction of the pivot shaft 3).

  Therefore, if the auto tensioner 1 of the present embodiment is used, it is possible to effectively suppress an excessive displacement of the arm portion 5 due to a change in the belt tension, while being compact. Further, since the damping characteristic can be controlled separately from the torque characteristic, it is possible to limit a large fluctuation in belt tension while maintaining a low torque.

  The configuration of the auto tensioner described above is an example of the embodiment, and the configuration, shape, and the like of each member can be appropriately changed without departing from the gist of the present invention.

  As described above, the auto tensioner according to an example of the present disclosure can be applied to various vehicles.

DESCRIPTION OF SYMBOLS 1 Auto tensioner 2a, 2b, 7 Pulley 3 Pivot shaft 4 Drive pulley 5 Arm part 8 Elastic member 9 Cam 11 Energizing means 13 Washer 14, 18 Friction disk 15 Front plate 17 Bushing 18 Friction disk 19 Elastic member 21 Belt

Claims (3)

A shaft,
An arm portion rotatably attached to the shaft;
A pulley provided on the arm portion;
An elastic member connecting the arm part to the engine block;
A biasing means that is compressed and fastened to the shaft and biases the arm portion in an axial direction of the shaft;
An auto tensioner provided with any one of the urging means on the seat surface side, and a cam that changes a stroke in a thrust direction following the rotation of the arm portion. The auto tensioner according to claim 1,
The auto-tensioner characterized in that the biasing means is a disc spring. The auto tensioner according to claim 1 or 2,
A friction disk disposed between the urging means and the arm portion;
The auto tensioner according to claim 1, wherein a sliding resistance between the friction disk and the arm portion is changed by a change in stroke of the cam.

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