JP2004270858A - Spring seat and automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of a crack in a spring seat, in a tensioner using a ring-like spring seat. <P>SOLUTION: The ring-like spring seat 50 is installed to a bottom face of a tensioner cup. A cutout 51 is formed in a position corresponding to a tip 22b of a coil spring 22 in the spring seat 50. A contact part 28 in a shape suitable for the cutout 51 is disposed at a position corresponding to the cutout 51 in the bottom face of the tensioner cup. The thickness of the contact part 28 is approximately equal to that of the spring seat 50 at the periphery of cutout 51. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tensioner using a coil spring that adjusts belt tension according to belt slack, and more particularly to a spring seat interposed between a coil spring and a tensioner cup.
[0002]
[Prior art]
Conventionally, a tensioner using a coil spring is known. A tensioner using a coil spring includes, for example, a tensioner cup that houses the coil spring and a tensioner arm that is rotatably fitted to the tensioner cup and that rotatably holds a tensioner pulley at a position eccentric from its axis. Prepare. One end of the coil spring is fixed to, for example, the bottom of the tensioner cup, and the other end is fixed to the tensioner arm. That is, a rotational urging force is applied to the tensioner pulley by the coil spring via the tensioner arm.
[0003]
A spring seat is provided on the bottom surface of the tensioner cup to maintain the posture of the coil spring. A ring-shaped spring seat is used to improve the attachment of the spring seat to the tensioner cup and prevent incorrect assembly on the front and back.
[0004]
[Problems to be solved by the invention]
When a ring-shaped spring seat is used, the tip of the coil spring directly hits the spring seat, and there is a problem that a crack is generated therefrom.
[0005]
An object of the present invention is to prevent a spring seat from cracking in a tensioner using a ring-shaped spring seat.
[0006]
[Means for Solving the Problems]
The ring-shaped spring seat of the present invention is a ring-shaped spring seat used in an auto tensioner in which a coil spring is installed, and the tip of the coil spring contacts the spring seat at a position corresponding to the tip of the coil spring. A notch or an opening is provided so as not to cause the problem.
[0007]
Preferably, a notch is provided on the outer peripheral edge of the spring seat. At this time, it is preferable that the inner peripheral edge of the spring seat in the portion provided with the notch protrudes inward.
[0008]
Further, the auto tensioner of the present invention is an auto tensioner in which a coil spring is provided, and a ring-shaped spring seat is interposed between the coil spring and the bottom surface of the tensioner cup. A notch or an opening is provided at a corresponding position so that this tip does not contact the spring seat, and a contact portion that contacts the tip of the coil spring at a position corresponding to the notch or opening on the bottom surface of the tensioner cup. Is provided.
[0009]
The thickness of the abutment is preferably substantially equal to the thickness of the spring seat at the notch or opening. Also, when a notch is provided on the outer peripheral edge of the spring seat, the inner peripheral edge of the spring seat at the portion where the notch is provided projects inward to form an overhang, and the spring seat corresponds to this overhang. It is preferable that a recess is formed in the bearing portion of the tensioner cup along the inner peripheral edge of the tensioner cup.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of an auto-tensioner according to an embodiment of the present invention. FIG. 2 is a plan view when the tensioner cup shown in FIG. 1 is viewed from the direction of the opening. Note that the cross-sectional view of FIG. 1 corresponds to the cross-section taken along line II of FIG.
[0011]
The auto-tensioner 10 according to the present embodiment includes a tensioner cup 20 fixed to an engine block (not shown), a tensioner arm 30 rotatable around a swing axis Lc with respect to the tensioner cup 20, and a tensioner arm. 30 and a tensioner pulley 40 attached to the tensioner pulley 30. The tensioner cup 20 has a cylindrical cup shape, and a bearing portion 21 for supporting the rotation shaft 31 of the tensioner arm 30 is formed at the center of the bottom surface so as to protrude inside the tensioner cup 20.
[0012]
The tensioner arm 30 is fitted into the opening 23 of the tensioner cup 20, and covers and entirely covers the opening 23. The hollow rotary shaft 31 is formed at the center of the bottom surface of the tensioner arm 30, and a pulley mounting portion 32 for mounting the pulley 40 is formed near the periphery of the bottom surface. The rotating shaft 31 is rotatably fitted into a shaft hole of the bearing portion 21 of the tensioner cup 20. A pulley 40 is mounted on the pulley mounting portion 32 via a ball bearing 41. That is, the inner race of the ball bearing 41 is fixed to the pulley mount 32 by the bolt 32 a screwed to the pulley mount 32, and the outer race is fixed to the boss of the pulley 40. Thus, the pulley 40 is rotatable about a rotation axis Lp that is coaxial with the axis of the bolt 32a. A washer 32b is interposed between the head of the bolt 32a and the inner ring of the ball bearing 41, and the washer 32b also serves as a dust shield.
[0013]
The shaft hole of the bearing portion 21 of the tensioner cup 20 communicates the inside and the outside of the tensioner cup 20, and the rotation shaft 31 of the tensioner arm is rotatably fitted into the bearing portion 21 from inside the tensioner cup 20. A female screw is formed on the inner peripheral surface of the hollow rotary shaft 31, and a bolt 31a is screwed therein. At this time, a washer 31b is interposed between the head of the bolt 31a and the rotating shaft 31. The washer 31b engages with a stepped portion 21a formed on the inner peripheral surface of the bearing portion 21 via the bushing 26, and regulates the axial movement of the rotary shaft 31. The bushing 26 is a sleeve member interposed between the bearing portion 21 and the rotating shaft 31, and has a flange portion sandwiched between the washer 31b and the step portion 21a.
[0014]
A coil spring 22 is provided in the tensioner cup 20, and a ring-shaped spring seat 50 made of a resin material or the like is interposed between the coil spring 22 and the bottom surface of the tensioner cup 20. As shown in FIG. 2, the spring seat 50 is formed in substantially the same shape as an annular bottom surface formed between the inner peripheral surface of the tensioner cup 20 and the bearing 21.
[0015]
One end of the coil spring 22 is linearly bent, and a straight portion (string) of a spring locking portion 27 that protrudes in a chord shape from the inner peripheral surface of the tensioner cup 20 and a spring portion that protrudes from the bearing portion 21. It is fitted between the linear portion of the locking portion 27 and the thick portion 21A having a side surface parallel to the locking portion 27, and regulates the movement of the coil spring 22 in the rotation direction. The other end of the coil spring 22 is fixed to the bottom surface of the tensioner arm 30. The coil spring 22 is arranged in the tensioner cup 20 such that the spiral axis thereof substantially coincides with the rotation axis 31. Further, the coil spring 22 is slightly compressed and twisted during assembly and is incorporated into the tensioner cup 20, so that the tensioner arm 30 is given a rotational bias about the axis Lc with respect to the tensioner cup 20. .
[0016]
The peripheral edge of the tensioner arm 30 has, for example, a double cylindrical structure. That is, the tensioner arm 30 includes an outer ring portion 33 that is the outermost and forms a cylindrical outer peripheral surface, and a cylindrical inner ring portion 34 that is formed inside the outer ring portion 33. The inner diameter of the outer ring 33 is larger than the outer diameter of the opening 23 of the tensioner cup 20, and the outer diameter of the inner ring 34 is smaller than the inner diameter of the opening 23 of the tensioner cup 20. The opening portion 23 of the tensioner cup 20 is fitted between the outer ring portion 33 and the inner ring portion 34, and a damping band 24 extends over the entire circumference between the outer peripheral surface of the inner ring portion 34 and the inner peripheral surface of the opening 23. Is interposed. That is, the tensioner arm 30 swings around the axis Lc in accordance with the fluctuation of the belt load applied to the pulley 40, and at this time, the outer peripheral surface of the inner ring portion 34 of the tensioner arm 30 is Sliding contact with the inner peripheral surface of the band 24 generates a damping force.
[0017]
The attachment of the tensioner 10 to the engine block is performed by vertically projecting from the outer peripheral surface of the tensioner cup 20 and fixing, for example, three fixing portions 25 formed in a plate shape with bolts.
[0018]
Next, details of the spring seat 50 of the present embodiment will be described with reference to FIGS. FIG. 3 shows the arrangement of the end of the coil spring 22 and the spring seat 50, and the end 22 a of the coil spring 22 fixed to the tensioner cup 20 is partially shown. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a view as seen from the direction of arrow V in FIG.
[0019]
As shown in FIG. 3, the linearly bent end portion 22 a of the coil spring 22 is provided with a spring engagement portion 27 provided on the inner peripheral surface of the tensioner cup 20 and a thick portion provided on the bearing portion 21. 21A and fitted in a linear groove sandwiched between the grooves 21A and 21A. In the spring seat 50, a portion corresponding to the tip 22 b of the end 22 a is partially cut out so that the tip 22 b of the coil spring 22 does not contact the spring seat 50, and a notch 51 is formed. In the present embodiment, the notch 51 is formed in a substantially semicircular shape on the outer peripheral edge of the spring seat 50, and on the inner peripheral edge of the spring seat 50, a protrusion protruding inward in a substantially arc shape corresponding to the notch 51. A protrusion 52 is formed. That is, in the portion where the notch 51 is provided, the width of the spring seat 50 becomes narrow, so the overhang portion 52 is formed to reinforce this. The bearing 21 has a recess 21 </ b> B corresponding to the overhang 52.
[0020]
On the other hand, in a region corresponding to the notch 51 on the bottom surface of the tensioner cup 20, a contact portion 28 which is a flat protrusion having a shape adapted to the shape of the notch 51 is provided with a seat for receiving the tip 22 b of the coil spring 22. Is formed as The thickness of the contact portion 28 is substantially equal to the thickness of the spring seat 50 at the position where the notch 51 is provided. As shown in FIG. 4, when the coil spring 22 is mounted on the spring seat 50, the tip 22 b of the coil spring 22 is located on the contact portion 28. Since the contact portion 28 is formed to have substantially the same thickness as the spring seat 50, the force applied to the tip 22 b of the coil spring 22 acts only on the contact portion 28, and stress is concentrated on the spring seat 50. Never. In this embodiment, the contact portion 28 is formed integrally with the bottom surface of the tensioner cup.
[0021]
Further, in the present embodiment, the spring seat 50 is formed to have substantially the same thickness over substantially the entire circumference. However, in order to stably support the spiral coil spring 22, a fan-shaped support portion is provided at a part thereof. 53 are formed (see FIG. 3). As shown in FIG. 5, the support portion 53 forms an inclined surface that is inclined along the circumferential direction, and the inclined surface contacts the spiral coil spring 22 to maintain the posture of the coil spring 22.
[0022]
As described above, according to the present embodiment, since the notch is provided in the spring seat, the tip of the coil spring does not directly hit the spring seat. Can be prevented. In addition, a contact portion of approximately the same thickness as the spring seat is provided at the portion corresponding to the notch of the spring seat as a seat at the tip of the coil spring, so that the edge of the notch is in contact with the bottom surface of the coil spring and the tensioner cup. Between the spring seats can be prevented, and the generation of cracks in the spring seat can be more reliably prevented.
[0023]
Although the spring seat of the present embodiment has a substantially arc-shaped overhanging portion corresponding to the notch portion, the spring seat is provided on the spring seat 50 ', for example, as in a modification shown in FIG. If the strength is sufficiently secured for the notch 51 ', it is not necessary to provide an overhang.
[0024]
In addition, it goes without saying that various shapes such as an elliptical shape and a trapezoidal shape can be applied to the shape of the notch and the shape of the contact portion other than the present embodiment. When the spring seat has a sufficient width, an opening (for example, a circular opening) can be provided in the center of the spring seat instead of the notch, and the shape of the tip of the coil spring and the torsional force to be applied can be reduced. Depending on the direction, a notch can be provided on the inner peripheral edge side of the spring seat.
[0025]
In the present embodiment, the support portion having the inclined surface for supporting the spiral coil spring is provided only at one place, but a plurality of support portions may be provided, or the entire circumference of the spring seat may be provided on the inclined surface. It may be. At this time, the thickness of the contact portion may be approximately equal to the thickness of the spring seat on the side where the end of the coil spring is placed.
[0026]
【The invention's effect】
As described above, according to the present invention, in a tensioner using a ring-shaped spring seat, generation of cracks in the spring seat can be prevented.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an auto tensioner according to an embodiment of the present invention.
FIG. 2 is a plan view of the tensioner cup shown in FIG. 1 as viewed from a direction of an opening.
FIG. 3 is a diagram showing an arrangement of an end of a coil spring and a spring seat.
FIG. 4 is an enlarged sectional view taken along a line IV-IV in FIG. 3;
FIG. 5 is an enlarged view from the direction of arrow V in FIG. 3;
FIG. 6 is a partially enlarged view showing a shape around a notch of a spring seat according to a modified example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Auto tensioner 20 Tensioner cup 21A Thick part 22 Coil spring 22b Tip 27 Spring locking part 28 Contact part 50 Spring seat 51 Notch 52 Overhang

Claims (7)

A ring-shaped spring seat used in an auto tensioner provided with a coil spring,
A ring-shaped spring seat, wherein a notch or an opening is provided at a position corresponding to the tip of the coil spring so that the tip does not contact the spring seat. The spring seat according to claim 1, wherein the notch is provided on an outer peripheral edge of the spring seat. The spring seat according to claim 2, wherein an inner peripheral edge of the spring seat at a portion where the notch is provided projects inward. An auto tensioner in which a coil spring is provided, and a ring-shaped spring seat is interposed between the coil spring and a bottom surface of the tensioner cup,
A notch or an opening is provided at a position corresponding to the tip of the coil spring on the spring seat so that the tip does not contact the spring seat, and corresponds to the notch or the opening on the bottom surface of the tensioner cup. An auto-tensioner, wherein an abutting portion that abuts on the tip of the coil spring is provided at a position where the coil spring is located. The auto-tensioner according to claim 4, wherein a thickness of the contact portion is substantially equal to a thickness of the spring seat at the notch or the opening. The auto-tensioner according to claim 4, wherein the notch is provided on an outer peripheral edge of the spring seat. The inner peripheral edge of the spring seat in the portion provided with the notch projects inward to form an overhang portion, and the tensioner cup bearing along the inner peripheral edge of the spring seat corresponding to the overhang portion The auto-tensioner according to claim 6, wherein a concave portion is formed in the portion.

Images