JP6761911B1 - Auto tensioner - Google Patents

Abstract

The fixed-side tongue 42 of the torsion coil spring 40 is locked to the fixed-side locking portion, while the swing-side tongue 43 of the torsion coil spring 40 is locked to the swing-side locking portion of the base member 10. The foreign matter prevention member 50 and the coil portion 41 of the torsion coil spring 40 are arranged in the fixed side cup portion 11, the fixed side tongue 42 of the torsion coil spring 40 is locked to the fixed side locking portion, and the torsion coil spring 40 The swing-side tongue 43 is locked to the swing-side locking portion, the opening of the swing-side cup portion 21 of the arm member 20 faces the opening of the fixed-side cup portion 11 of the base member 10, and the arm member 20 In a temporarily assembled state in which the separation of the base member 10 of the swing-side cup portion 21 from the fixed-side cup portion 11 in the swing axis P direction is not regulated by the regulating means, the foreign matter prevention member 50 is on the fixed-side cup portion 11 open side. Is located inside the swing-side cup portion 21 of the arm member 20.

Description

The technique disclosed herein relates to an auto tensioner that applies tension to a belt such as an auxiliary drive belt of an automobile engine and automatically adjusts the tension application operation in response to the tension fluctuation, and particularly, foreign matter invades. Regarding measures to prevent.

Patent Document 1 has a bottomed tubular fixed-side cup portion, a base member attached to the fixed side, and a bottomed tubular swing-side cup portion, which comes into contact with a predetermined belt. A belt pressing portion for pressing the belt is attached, and the swinging side cup portion is arranged so that the fixed side cup portion of the base member and the opening face each other to form an internal space between the two cup portions. The arm member supported by the base member so as to swing around the swing axis so that the belt pressing portion is displaced in the belt pressing direction and the anti-belt pressing direction, and the shaft is substantially parallel to the swing axis. A torsion coil spring having a coil portion housed in the internal space in a state of being compressed in the axial direction, and constantly rotating and urging the arm member with respect to the base member in the belt pressing direction. , The regulating means for restricting the separation of the swing-side cup portion of the arm member from the fixed-side cup portion of the base member in the swing axis direction, and the coil portion of the torsion coil spring outside the radial direction in the internal space. An auto equipped with a foreign matter prevention member that is fixed to the fixed side cup portion of the base member so as to cover from the side and that regulates foreign matter that has entered the internal space from the gap between the two cup portions inward in the radial direction. The tensioner is disclosed. In this auto tensioner, a fixed-side locking portion is formed on the fixed-side cup portion of the base member, while a swing-side locking portion is formed on the swing-side cup portion of the arm member. The fixed-side tongue of the torsion coil spring is locked to the fixed-side locking portion, while the swing-side tongue of the torsion coil spring is locked to the swing-side locking portion.

Japanese Unexamined Patent Publication No. 2009-185984

The technique disclosed in the present specification is characterized in that the end portion of the foreign matter prevention member on the arm member side is arranged inside the swing side cup portion of the arm member in a temporarily assembled state.

The technology disclosed herein has a bottomed tubular fixed side cup portion, a base member attached to the fixed side, and a bottomed tubular swinging side cup portion on a predetermined belt. A belt pressing portion for contacting and pressing the belt is attached, and the swinging side cup portion makes the fixed side cup portion of the base member and the openings face each other to form an internal space between the two cup portions. An arm member supported by the base member so as to swing around the swing shaft so that the belt pressing portion is displaced in the belt pressing direction and the anti-belt pressing direction, and the shaft is the swing shaft. It has a coil portion housed in the internal space in a state of being compressed in the axial direction so as to be substantially parallel to the base member, and constantly rotates and urges the arm member with respect to the base member in the belt pressing direction. The torsion coil spring, the regulating means for restricting the separation of the swing side cup portion of the arm member from the fixed side cup portion of the base member in the swing axis direction, and the coil portion of the torsion coil spring in the internal space. Is fixed to the fixed-side cup portion of the base member so as to cover from the outside in the radial direction, and a foreign matter prevention member that regulates foreign matter that has entered the internal space from the gap between the two cup portions inward in the radial direction. An auto tensioner provided with an outward flange shape provided between the base member and the arm member in a circumferential direction portion of a cylindrical sliding contact portion and one opening edge of the sliding contact portion. An insert member having a flange portion is interposed, and the torsion coil spring has a fixed side tongue that protrudes outward in the radial direction from one end of the coil portion and a radial outward from the other end of the coil portion. A shaft portion is erected on the bottom wall of the fixed-side cup portion of the base member, and the fixed-side cup portion of the base member and the foreign matter prevention member are further provided. A fixed-side locking portion is formed on at least one of them, and a boss portion is provided on the bottom wall of the swing-side cup portion of the arm member so as to be externally fitted from the tip end side of the shaft portion of the base member. A swing-side locking portion is formed on the swing-side cup portion of the arm member, and the foreign matter prevention member projects inward to a tubular portion and a part of the one end edge of the tubular portion. It has a protruding wall portion, and the fixed side tongue of the torsion coil spring is locked to the fixed side locking portion, while the swing side tongue of the torsion coil spring is on the swing side. It is locked to the locking portion, and the boss portion of the arm member is rotatably externally fitted to the shaft portion of the base member from the tip end side of the shaft portion. The sliding contact portion of the insert member is externally fitted to the boss portion of the arm member so as to be slidable, and the flange portion of the insert member is the end portion of the coil portion on the fixed side tongue side and the base member. It is arranged between the bottom wall of the fixed side cup portion, and is held in a sandwiched pressure between the two by the compressive force of the coil portion, and the protruding wall portion of the foreign matter prevention member is the circumference of the flange portion of the insert member. Arranged at positions that do not overlap in the direction, the bottom wall of the fixed side cup portion of the base member is brought into contact with the fixed side cup portion open side , and the foreign matter prevention member and the torsion coil spring are placed in the fixed side cup portion of the base member. The coil portion is arranged, the fixed side tongue of the torsion coil spring is locked to the fixed side locking portion, and the swing side tongue of the torsion coil spring is locked to the swing side locking portion. The opening of the swing side cup portion of the arm member is opposed to the opening of the fixed side cup portion of the base member, and the swing axis direction of the swing side cup portion of the arm member with respect to the fixed side cup portion of the base member. The end portion of the foreign matter prevention member on the fixed side cup portion open side is located inside the swing side cup portion of the arm member in a temporarily assembled state in which the separation from the foreign object prevention member is not regulated by the regulation means. And.

FIG. 1 is a vertical cross-sectional view showing the overall configuration of the auto tensioner according to the embodiment of the present invention. FIG. 2 is a perspective view showing a state in which the insert member and the foreign matter prevention member are arranged in the fixed side cup portion of the base member. FIG. 3 is a cross-sectional view corresponding to lines III-III of FIG. FIG. 4 is a cross-sectional view corresponding to line IV-IV of FIG. FIG. 5 is a perspective view of the foreign matter prevention member. FIG. 6 is a perspective view of a foreign matter prevention member and a torsion coil spring. FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. FIG. 8 is a diagram corresponding to FIG. 4 in a temporarily assembled state.

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

FIG. 1 shows the overall configuration of the auto tensioner 1 according to the embodiment of the present invention, in which the auto tensioner 1 supplements a part of the output torque of an automobile engine via one transmission belt B. It is used in a belt-type auxiliary drive device with a serpentine layout that is transmitted to the machine, and while performing an operation of applying a predetermined tension to the transmission belt B, the above is performed according to fluctuations in the belt tension. It is designed to automatically change the damping force for the operation of.

The auto tensioner 1 includes a base member 10 fixed to the engine as a fixed side, an arm member 20 swayably supported by the base member 10 around a swing shaft P, a base member 10 and an arm member 20. It is provided with an insert member 30 interposed between the two. In the belt-type auxiliary drive device, the output shafts such as the crankshaft in the case of a reciprocating engine are arranged so as to be substantially horizontal, and the above-mentioned transmission belt B is arranged so as to run in a substantially vertical plane. Therefore, the auto tensioner 1 is arranged so that the swing shaft P is substantially horizontal.

As shown in FIGS. 2 to 4, the base member 10 includes a bottomed tubular fixed-side cup portion 11 and a shaft portion 12 erected in the center of the bottom wall in the fixed-side cup portion 11. Has. The outer peripheral surface of the shaft portion 12 is formed in a tapered cross section in which the outer diameter gradually decreases toward the tip side, and the shaft portion 12 is axially formed on the swing shaft P portion of the shaft portion 12. A bolt hole 13 that penetrates is provided. A mounting portion (not shown) is provided on the outer periphery of the fixed side cup portion 11, and the base member 10 is fixed to the engine by bolts (not shown) at these mounting portions and the bolt holes 13. There is. Further, a part of the side peripheral wall of the fixed side cup portion 11 in the circumferential direction is engaged as a slit-shaped fixed side locking portion that penetrates the side peripheral wall in the radial direction and reaches a position near the bottom wall to a position near the opening. A stop hole 14 is formed. Further, a positioning hole 15 (see FIG. 2) penetrating the bottom wall is formed in the bottom wall of the fixed side cup portion 11.

On the other hand, the arm member 20 can be externally fitted to the bottomed tubular swing-side cup portion 21 and the center of the bottom wall of the swing-side cup portion 21 from the tip end side of the shaft portion 12 of the base member 10. It has a boss portion 22 provided in the. The boss portion 22 is formed so as to extend from the bottom wall of the swing-side cup portion 21 toward the opening side of the swing-side cup portion 21, and its inner peripheral surface is an opening of the swing-side cup portion 21. It is formed in a tapered cross section in which the inner diameter gradually increases toward the side. The taper angle of the inner peripheral surface of the boss portion 22 is substantially the same as the taper angle of the outer peripheral surface of the shaft portion 12. In this arm member 20, the fixed side cup portion 11 of the base member 10 and the openings face each other to form an internal space S between the cup portions 11 and 21, and the boss portion 22 is on the shaft portion 12 of the base member 10. It is arranged in a state of being rotatably externally fitted from the tip end side of the shaft portion 12. The shaft portion 12 penetrates the boss portion 22 in the axial direction, and the tip portion thereof protrudes in the axial direction from the bottom wall of the swing-side cup portion 21. A front plate 23, which has a substantially disk shape and has an outer diameter larger than the inner diameter of the boss portion 22 as a regulating means, is fixed to the tip portion so as not to rotate by crimping. 22 is prevented from coming out of the shaft portion 12. That is, the front plate 23 regulates the separation of the swing-side cup portion 21 of the arm member 20 from the fixed-side cup portion 11 of the base member 10 in the swing axis P direction. Further, a recess 21a as a swing-side locking portion recessed on the outer peripheral side is formed in a part of the side peripheral wall of the swing-side cup portion 21 in the circumferential direction.

An arm portion 24 is provided on the outer periphery of the swing-side cup portion 21 so as to project outward in the radial direction, and a pulley holding portion 25 is provided at the tip of the arm portion 24. .. The pulley holding portion 25 is formed with a bolt hole 26 extending in a direction parallel to the swing shaft P. A bearing 27 is attached to the tip of the pulley holding portion 25 by a flange portion of a flanged bolt 28 screwed into a bolt hole 26, and a pulley 29 as a belt pressing portion is rotationally integrally externally fitted to the bearing 27. By doing so, the pulley 29 is attached to the arm member 20 via the bearing 27. The pulley 29 comes into contact with the transmission belt B and rotates around the center of the pulley axis while being displaced in the belt pressing direction and the anti-belt pressing direction that press the transmission belt B.

The insert member 30 is a pair of a substantially cylindrical bearing portion 31, a substantially flanged semi-cylindrical spring support portion 32, and a pair of the bearing portion 31 and the spring support portion 32 connected at both ends in the circumferential direction of the spring support portion 32. It is provided with a connecting portion 33 of.

A bearing portion 31 of the insert member 30 is interposed between the boss portion 22 of the arm member 20 and the shaft portion 12 of the base member 10, and the arm member 20 is a base member via the bearing portion 31. 10 is supported so as to be swingable around the swing shaft P. The inner and outer peripheral surfaces of the bearing portion 31 are each formed to have a tapered cross section. The taper angle of the inner peripheral surface is substantially the same as the outer peripheral surface of the shaft portion 12, and the taper angle of the outer peripheral surface is substantially the same as the inner peripheral surface of the boss portion 22. Further, a disk-shaped thrust washer 34 made of the same material as the insert member 30 is interposed between the front plate 23 and the bottom wall of the swing-side cup portion 21 of the arm member 20.

Between the base member 10 and the arm member 20, the arm member 20 is constantly rotated with respect to the base member 10 so as to rotate around the swing shaft P in the direction of pressing the transmission belt B with the pulley 29. An urging torsion coil spring 40 is interposed. The torsion coil spring 40 includes a coil portion 41, a fixed-side tongue 42 protruding outward in the radial direction from an end (one end portion) of the coil portion 41 on the base member 10 side, and an arm of the coil portion 41. It has a swing-side tongue 43 that protrudes outward in the radial direction from the end (other end) on the member 20 side. The coil portion 41 is attached to the boss portion 22 of the arm member 20 from the outer peripheral side, and is compressed in the axial direction so that the axis of the coil portion 41 is substantially parallel to the swing axis P in the internal space S. It is contained. As shown in FIG. 3, the fixed-side tongue 42 is locked to the locking hole 14 of the base member 10 and the notch 53 of the foreign matter prevention member 50 described later, whereby the circumference of the fixed-side tongue 42 is peripheral. Directional movement is restricted. On the other hand, the swing-side tongue 43 is locked in the recess 21a of the arm member 20, thereby restricting the movement of the swing-side tongue 43 in the circumferential direction.

The torsion coil spring 40 is interposed between the base member 10 and the arm member 20 in a state where the coil portion 41 is twisted in the direction of reducing the diameter, and thus the torsion torque in the direction of increasing the diameter of the coil portion 41. Therefore, the arm member 20 is rotationally urged. Further, the torsion coil spring 40 is interposed in a state where the coil portion 41 is compressed in the axial direction, whereby the thrust washer 34 is the swinging side cup portion of the front plate 23 and the arm member 20. It is in a state of being sandwiched between the 21 and the 21.

A spring support portion 32 of the insert member 30 is interposed between the coil portion 41 of the torsion coil spring 40 and the boss portion 22 of the arm member 20. The spring support portion 32 has a cylindrical sliding contact portion 32a that is externally fitted on the boss portion 22 of the arm member 20 and can be slidably contacted with the boss portion 22, and one opening of the sliding contact portion 32a. It is composed of an outward flange-shaped flange portion 32b provided on substantially half of the circumferential direction of the edge. A positioning protrusion 32c (see FIG. 2) is projected on the surface of the collar portion 32b on the side of the counter-sliding contact portion 32a. The positioning protrusion 32c is engaged with the positioning hole 15 of the fixed side cup portion 11 of the base member 10, whereby the spring support portion 32 is positioned in the circumferential direction with respect to the base member 10. .. The flange portion 32b is arranged between the end of the coil portion 41 on the fixed side tongue 42 side and the bottom wall of the fixed side cup portion 11 of the base member 10, and is sandwiched between the two by the compressive force of the coil portion 41. The sandwiching pressure is held, so that the spring support portion 32 is non-rotatably fixed to the base member 10 side.

Further, in the internal space S formed between the fixed side cup portion 11 of the base member 10 and the swinging side cup portion 21 of the arm member 20, a resin foreign matter prevention member 50 is formed in the coil of the torsion coil spring 40. The portion 41 is arranged so as to cover the portion 41 from the outside in the radial direction, and regulates foreign matter that has entered the internal space S through the gap between the cup portions 11 and 21 from entering in the radial direction.

As shown in FIGS. 5 to 7, the foreign matter prevention member 50 has a cylindrical tubular portion 51, and projects inward at a portion of one end edge of the tubular portion 51 that is slightly shorter than the circumferential half. collision Dekabe portion 52 is projected you. A notch 53 as a U-shaped fixed-side locking portion is formed at a position close to one end of the protruding wall portion 52 in the circumferential direction at one end edge of the tubular portion 51. In the vicinity of both ends in the circumferential direction of the protruding wall portion 52, a pair of seat portions 54, 55 having flat surfaces 54a, 55a at the tips thereof are directed toward the other end side of the tubular portion 51 from the side closer to the notch portion 53. It is thrust in order. These seat portions 54 and 55 are continuous with the tubular portion 51 from the inner peripheral side. The protruding height of the seat portion 54 closer to the notch 53 is higher than the protruding height of the other seat portion 55. The protruding wall portion 52 is arranged at a position where it does not overlap with the flange portion 32b of the spring support portion 32 of the insert member 30 in the circumferential direction. Then, the protruding wall portion 52 of the foreign matter prevention member 50 is in contact with the bottom wall of the fixed side cup portion 11 of the base member 10 from the open side of the fixed side cup portion 11, while the seat portions 54, 55 of the foreign matter prevention member 50. The flat surfaces 54a and 55a of the above are in contact with the coil portion 41 of the torsion coil spring 40 from the non-open side of the fixed side cup portion 11. Therefore, the protruding wall portion 52 and the seat portions 54, 55 of the foreign matter prevention member 50 are arranged between the end portion of the coil portion 41 on the fixed side tongue 42 side and the bottom wall of the fixed side cup portion 11 of the base member 10. The foreign matter prevention member 50 is non-rotatably fixed to the base member 10 side by the compressive force of the coil portion 41.

Here, the operation of the auto tensioner 1 configured as described above will be described. In the auto tensioner 1, when the tension of the transmission belt B decreases with the operation of the automobile engine, the arm member 20 rotates in the belt pressing direction by the torsional torque of the torsion coil spring 40, and the pulley 29 pushes the transmission belt. Since it is pressed, the decrease in belt tension is suppressed, while when the tension of the transmission belt B increases, the pulley 29 is pressed by the belt reaction force, and the arm member 20 rotates in the direction opposite to the belt pressing direction. Therefore, the increase in belt tension is suppressed.

On the other hand, due to the reaction force of the torsional torque of the torsion coil spring 40, a part of the coil portion 41 of the torsion coil spring 40 in the circumferential direction is always pressed inward in the radial direction, whereby the arm member 20 is pressed. A part of the boss portion 22 in the circumferential direction is sandwiched between the sliding contact portion 32a of the spring support portion 32 of the insert member 30 and the bearing portion 31. Therefore, as the arm member 20 swings, sliding friction is generated between the sliding contact portion 32a and the boss portion 22 of the spring support portion 32 and between the bearing portion 31 and the boss portion 22, respectively. Acts as a damping force that damps the swing of the arm member 20. At that time, the reaction force of the torsional torque decreases when the arm member 20 rotates in the belt pressing direction, that is, when the coil portion 41 expands in diameter, so that the damping force also decreases. Therefore, the arm member 20 is quickly rotated. On the other hand, when the arm member 20 rotates in the direction opposite to the belt pressing direction, that is, when the coil portion 41 has a reduced diameter, the arm member 20 rises accordingly, so that the damping force also rises.

As a result, when the belt tension decreases, the auto tensioner 1 promptly presses the transmission belt B to suppress the decrease in the belt tension, while when the belt tension increases, the auto tensioner 1 gently absorbs the increase in the belt reaction force. It suppresses the increase in belt tension. By doing so, fluttering of the transmission belt B due to tension fluctuation is avoided, thereby suppressing slippage of the transmission belt B with respect to the auxiliary pulley, ensuring torque transmission, and the life of the transmission belt B. The shortening of life will be prevented.

In order to assemble the auto tensioner 1 configured as described above, first, the insertion member 30 is inserted into the fixed side cup portion 11 of the base member 10, and the positioning protrusion 32c thereof is inserted into the positioning hole 15 of the base member 10. The foreign matter prevention member 50 is placed in such a manner, the protruding wall portion 52 abuts on the bottom wall of the fixed side cup portion 11 of the base member 10, and the notch portion 53 corresponds to the locking hole 14 of the base member 10. Place it like this. In this way, the foreign matter prevention member 50 is brought into contact with the fixed side cup portion 11 of the base member 10 simply by bringing the protruding wall portion 52 into contact with the bottom wall of the fixed side cup portion 11 of the base member 10. Since the coil portion can be positioned in the 41-axis direction, the foreign matter prevention member 50 can be easily positioned with respect to the fixed side cup portion 11 of the base member 10. Further, the foreign matter prevention member 50 can be positioned in the circumferential direction of the coil portion 41 with respect to the fixed side cup portion 11 of the base member 10 only by making the notch 53 of the foreign matter prevention member 50 correspond to the locking hole 14 of the base member 10. Therefore, the work of positioning the foreign matter prevention member 50 with respect to the fixed side cup portion 11 of the base member 10 is easy. Next, the coil portion 41 of the torsion coil spring 40 is substantially aligned with the swing shaft P on the flange portion 32b of the spring support portion 32 of the insert member 30 and the seat portions 54 and 55 of the foreign matter prevention member 50. Place them so that they are parallel. As a result, the coil portion 41 of the torsion coil spring 40 is arranged in the fixed side cup portion 11 of the base member 10. Next, the fixed side tongue 42 of the torsion coil spring 40 is locked to the locking hole 14 of the fixed side cup portion 11 of the base member 10 and the notch 53 of the foreign matter prevention member 50, and the swing side of the torsion coil spring 40. The tongue 43 is locked in the recess 21a of the swing-side cup portion 21 of the arm member 20. In this way, the foreign matter prevention member 50 is twisted simply by locking the fixed side tongue 42 of the torsion coil spring 40 into the locking hole 14 of the fixed side cup portion 11 of the base member 10 and the notch 53 of the foreign matter prevention member 50. Since the coil spring 40 can be positioned in the circumferential direction of the coil portion 41, the foreign matter prevention member 50 can be easily positioned with respect to the torsion coil spring 40. Then, as shown in FIG. 8, by inserting the shaft portion 12 of the base member 10 into the boss portion 22 of the arm member 20 via the bearing portion 31 of the insert member 30, the swing-side cup portion 21 of the arm member 20 is inserted. Is temporarily assembled so that the opening of the base member 10 faces the opening of the fixed side cup portion 11 of the base member 10. In this temporarily assembled state, the front plate 23 is not attached to the base member 10, and the separation of the swing side cup portion 21 of the arm member 20 from the fixed side cup portion 11 of the base member 10 in the swing axis P direction is restricted. It has not been. Therefore, the position of the swing-side cup portion 21 of the arm member 20 in the swing axis P direction depends on the length of the torsion coil spring 40 in the swing axis P direction in a state where it is not compressed in the axial direction. In this temporarily assembled state, the end E on the open side of the fixed side cup portion 11 of the foreign matter prevention member 50 is located inside the swing side cup portion 21 of the arm member 20. Then, from this temporarily assembled state, the swing-side cup portion 21 of the arm member 20 is pressed in the opening direction thereof, and the coil portion 41 of the torsion coil spring 40 is compressed in the axial direction, and the shaft portion of the base member 10 is compressed. The front plate 23 is fixed to the tip portion of 12 by crimping.

By the way, in the auto tensioner of Patent Document 1, the foreign matter prevention member and the coil portion of the torsion coil spring are arranged in the fixed side cup portion of the base member, and the fixed side tongue of the torsion coil spring is locked on the fixed side. The swing side tongue of the torsion coil spring is locked to the swing side locking portion, and the opening of the swing side cup portion of the arm member is opened to the fixed side cup portion of the base member. In a temporarily assembled state in which the swing-side cup portion of the arm member is opposed to the opening and the separation of the swing-side cup portion of the arm member from the fixed-side cup portion of the base member in the swing axis direction is not regulated by the regulation means. The swing side cup portion is pressed in the opening direction to compress the coil portion of the torsion coil spring in the axial direction, and in this state, the arm member is fixed to the base member in the coil portion axial direction by the above-mentioned regulating means. Can be assembled by. Here, in the temporarily assembled state, the end of the fixed-side cup portion of the foreign matter prevention member on the open side is located in the opening direction of the swing-side cup portion with respect to the open-side end of the swing-side cup portion of the arm member. Then, when the swing-side cup portion of the arm member is pressed, the foreign matter prevention member may interfere with the open-side end portion of the swing-side cup portion due to the inclination of the swing-side cup portion of the arm member. Therefore, it is necessary to adjust the position of the swing-side cup portion of the arm member so that the swing-side cup portion of the arm member and the foreign matter prevention member do not interfere with each other, which complicates the assembly work. Further, the foreign matter preventing member may press the swinging side cup portion of the arm member in a state where the foreign matter preventing member interferes with the open side end portion of the swinging side cup portion of the arm member, and the foreign matter preventing member may be crushed.

However, in the auto tensioner 1 according to the present embodiment, in the temporarily assembled state, the end E on the open side of the fixed side cup portion 11 of the foreign matter prevention member 50 is the open side end portion of the swing side cup portion 21 of the arm member 20. Since it is located in the direction opposite to the opening of the swing-side cup portion 21, even if the arm member 20 is tilted, when the swing-side cup portion 21 of the arm member 20 is pressed in the opening direction from the temporarily assembled state. , The end E on the open side of the fixed side cup portion 11 of the foreign matter prevention member 50 does not interfere with the open side end of the swing side cup portion 21. Therefore, it is possible to prevent the foreign matter prevention member 50 from being crushed by the swing-side cup portion 21 of the arm member 20. Further, since it is not necessary to adjust the position of the swing-side cup portion 21 of the arm member 20 so that the foreign matter prevention member 50 does not interfere with the swing-side cup portion 21 of the arm member 20 when pressed, the auto tensioner 1 can be used. Assembling work can be done easily.

Therefore, according to the present embodiment, the torsion coil spring is in a state where the foreign matter prevention member 50 abuts the protruding wall portion 52 against the bottom wall of the fixed side cup portion 11 of the base member 10 from the fixed side cup portion 11 open side. Since the cup portion 11 on the fixed side is pressed against the open side by 40, rattling of the foreign matter prevention member 50 in the axial direction of the coil portion is prevented.

In the present embodiment, the locking hole 14 is provided in the fixed side cup portion 11 of the base member 10 and the notch portion 53 is provided in the foreign matter prevention member 50. However, the locking hole 14 of the base member 10 and the foreign matter prevention member are provided. Only one of the notch 53 of 50 may be provided as the fixing side locking portion.

Further, in the present embodiment, the foreign matter prevention member 50 is made of resin, but if it is a material that can be manufactured in the shape of the foreign matter prevention member 50, it may be made of a material other than resin such as metal such as aluminum die-cast. ..

The technique disclosed in the present specification is useful as an auto tensioner that applies tension to a belt such as an auxiliary drive belt of an automobile engine and automatically adjusts the tension applying operation according to the tension fluctuation.

1 Auto tensioner 10 Base member 11 Fixed side cup part
12 Shaft 14 Locking hole (fixed side locking)
20 Arm member
21 Swing side cup part
21a recess (rocking side locking part)
22 Boss 23 Front plate (regulatory means)
29 Pulley (belt pressing part)
30 insert member
32a sliding contact part
32b collar 40 torsion coil spring 41 coil
42 Fixed side tongue
43 Swing side tongue
50 Foreign matter prevention member
52 Protruding wall part 53 Notch part (fixed side locking part)
54 and 55 seat
B Transmission belt E End P Swing shaft S Internal space

Claims (2)

A base member that has a bottomed tubular fixed side cup and is attached to the fixed side,
It has a bottomed tubular swing-side cup portion, and a belt pressing portion for contacting and pressing a predetermined belt is attached, and the swing-side cup portion is a fixed-side cup portion of the base member. The openings are arranged so as to form an internal space between the two cup portions so as to face each other, and the belt pressing portion can swing around the swing axis so as to be displaced in the belt pressing direction and the anti-belt pressing direction. The arm member supported by the base member and
It has a coil portion housed in the internal space in a state where the shaft is compressed in the axial direction so as to be substantially parallel to the swing shaft, and the arm member is pushed toward the belt pressing direction with respect to the base member. A torsion coil spring that constantly rotates and urges,
Regulatory means for regulating the separation of the swing-side cup portion of the arm member from the fixed-side cup portion of the base member in the swing axis direction, and
In the internal space, the coil portion of the torsion coil spring is fixed to the fixed side cup portion of the base member so as to cover the coil portion from the outside in the radial direction, and foreign matter that has entered the internal space through the gap between the cup portions is inside the radial direction. It is an auto tensioner equipped with a foreign matter prevention member that regulates intrusion into the direction.
An insert member having a cylindrical sliding contact portion and an outward flange-shaped flange portion provided on a part of the opening edge of one of the sliding contact portions in the circumferential direction is interposed between the base member and the arm member. ,
The torsion coil spring has a fixed-side tongue that protrudes outward in the radial direction from one end of the coil portion and a swing-side tongue that protrudes outward in the radial direction from the other end of the coil portion. Have more
A shaft portion is erected on the bottom wall of the fixed side cup portion of the base member.
A fixed-side locking portion is formed on at least one of the fixed-side cup portion of the base member and the foreign matter prevention member.
A boss portion is provided on the bottom wall of the swing-side cup portion of the arm member so as to be externally fitted from the tip end side of the shaft portion of the base member.
A swing-side locking portion is formed on the swing-side cup portion of the arm member.
The foreign matter prevention member has a tubular portion and a protruding wall portion projecting inward at a part of one end edge of the tubular portion.
The fixed side tongue of the torsion coil spring is locked to the fixed side locking portion, while the swing side tongue of the torsion coil spring is locked to the swing side locking portion.
The boss portion of the arm member is rotatably externally fitted to the shaft portion of the base member from the tip end side of the shaft portion.
The sliding contact portion of the insert member is externally fitted to the boss portion of the arm member so as to be slidable, and the flange portion of the insert member is fixed to the end portion of the coil portion on the fixed side tongue side and the base member. It is arranged between the bottom wall of the side cup part, and is held under sandwiching pressure between the two by the compressive force of the coil part.
The protruding wall portion of the foreign matter prevention member is arranged at a position where it does not overlap with the flange portion of the insert member in the circumferential direction, and abuts on the bottom wall of the fixed side cup portion of the base member from the fixed side cup portion open side.
The foreign matter prevention member and the coil portion of the torsion coil spring are arranged in the fixed side cup portion of the base member, the fixed side tongue of the torsion coil spring is locked to the fixing side locking portion, and the torsion coil spring The swing-side tongue of the arm member is locked to the swing-side locking portion, the opening of the swing-side cup portion of the arm member is made to face the opening of the fixed-side cup portion of the base member, and the swing of the arm member. In a temporarily assembled state in which the separation of the moving side cup portion from the fixed side cup portion of the base member in the swing axis direction is not regulated by the regulating means, the end of the foreign matter prevention member on the fixed side cup portion open side. An auto tensioner characterized in that the portion is located inside the swing-side cup portion of the arm member. In the auto tensioner according to claim 1 ,
A seat portion is projected from the protruding wall portion of the foreign matter prevention member toward the other end side of the tubular portion, and the seat portion is fixed to the coil portion of the torsion coil spring from the opposite side of the cup portion. An auto tensioner characterized by being in contact.

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