JP2006029537A - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct to prevent dust or the like from being invaded from clearance between a stationary member and a rotating member of an auto tensioner and simultaneously to realize such a construction which includes sufficient strength without making weight heavy. <P>SOLUTION: In the auto tensioner A provided with the stationary member 1 which includes a stationary side cup-like member 1b, and the rotating member 2 including a rotating side cup-like member 2b which is rotatably mounted to the stationary member 1 and a pressing portion 2e which integrally rotates with the rotating side cup-like member 2b and simultaneously over which a belt is stretched to make it possible to run, it is formed with a step part 20 on opening end of at least one of the stationary side cup-like member 1b and the rotating side cup-like member 2b and the opening end of both the cup-like members overlap in axial direction and it is provided with ribs 21 extending from the step part 20 in axial direction on peripheral surface 2h of the cup-like member formed with the step part 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an auto tensioner.

A conventional auto tensioner is disclosed in Patent Document 1. The auto tensioner disclosed in Patent Document 1 includes a fixing member having a fixed cup-shaped member fixed to a fixed body such as an engine, a belt pressing portion around which a belt such as a timing belt is stretched, and the fixed cup-shaped member. And a rotating member that is rotatably attached to the fixed member. Then, this rotating member is urged to rotate in a certain direction by the fixed side cup-shaped member and the torsion coil spring housed inside the rotational side cup-shaped member, thereby maintaining the belt tension appropriately. ing.
JP 2002-5252 A

  By the way, in the auto tensioner disclosed in the above-mentioned patent document 1, in order to avoid wear between the two members when the rotating member rotates relative to the fixed member, the opening end and the rotating side of the fixed cup-shaped member are avoided. It faces the open end of the cup-shaped member with a predetermined gap.

  For this reason, when dust, rainwater, oil, or the like adheres to the auto tensioner, such as when the auto tensioner is used as an engine part, dust or the like may enter the auto tensioner from the gap. Inside the auto tensioner, there are disposed a damping member for imparting a rotation resistance to the rotation member, the torsion coil spring, and the like, and the entry of the dust and the like is not preferable.

  In order to solve such a problem, the fixed end and the rotating member are formed by overlapping the opening end of the fixed cup-shaped member and the opening end of the rotating cup-shaped member in the axial direction of the shaft. It may be possible to form a labyrinth between them.

  However, if a labyrinth structure in which the opening end portion of the cup-shaped member is bent and enlarged in a longitudinal sectional view, for example, is adopted, the opening end portion has a bent portion where the thickness is thin and stress is concentrated. The problem of being easily damaged by the shortage arises. In particular, when casting a fixing member or a rotating member, this problem becomes important when the opening end of the cup-shaped member is pushed out by the pushing pin in the mold drawing process. Therefore, a measure for reinforcing the strength by increasing the thickness of the entire cup-shaped member including the labyrinth structure can be considered, but such a configuration is not preferable because the cup-shaped member becomes heavy as a whole.

  The present invention has been made in view of the above points, and the purpose thereof is to make it difficult for dust and the like to enter from the gap between the fixing member and the rotating member of the auto tensioner. The object is to achieve sufficient strength and without increasing the weight.

  According to a first aspect of the present invention, there is provided a fixed member having a fixed cup-shaped member that is fixed to the fixed body and opens to the opposite side of the fixed body, and coaxial with the axis of the fixed cup-shaped member that opens to the fixed body And a rotation-side cup-shaped member that is rotatably attached to the fixing member, a belt pressing portion that rotates integrally with the rotation-side cup-shaped member and that the belt can run around. An auto tensioner provided with a rotation member having

  At least one of the fixed-side cup-shaped member and the rotating-side cup-shaped member has a stepped portion at its opening end, and the opening end portions of both the cup-shaped members overlap in the axial direction. And the rib extended in the said axial direction from the level | step-difference part shall be provided in the surrounding surface of the cup-shaped member in which the said level | step-difference part was formed.

  In the case of the above configuration, a constant tension is applied to the belt that contacts the belt pressing portion of the auto tensioner by rotating the rotating member with respect to the fixed member.

  At this time, a stepped portion is formed on at least one opening end of the fixed-side cup-shaped member of the fixed member and the rotating-side cup-shaped member of the rotating member. It overlaps in the direction of the heart. That is, the stepped portion overlaps the opening end portion of the opposing cup-shaped member. As a result, a so-called labyrinth that is bent in a longitudinal sectional view is formed in the gap between the opening end of the fixed cup-shaped member and the opening end of the rotating cup upper end. For this reason, it can prevent that dust etc. penetrate | invade from the clearance gap between a fixed side cup-shaped member and a rotation side cup-shaped member. Note that the labyrinth is a structure in which a bent passage is formed and water or the like hardly enters.

  The step portion is bent in a longitudinal sectional view. In general, such a stepped portion is weak in strength because stress concentrates on the bent portion of the stepped portion. Therefore, a rib extending from the step portion is formed on the peripheral surface of the cup-shaped member on which the step portion is formed, and the strength of the step portion is reinforced. In addition, since the rib extends in the axial direction, the strength is improved particularly with respect to a force acting in the axial direction. Therefore, even if a force acts on the stepped portion from the axial direction, the stepped portion can be prevented from being damaged due to insufficient strength. Furthermore, since it is reinforced by the rib, it is not necessary to take measures such as increasing the thickness of the main body and the stepped portion to reinforce the strength of the stepped portion, and the rotating member can be reduced in weight.

  According to a second invention, in the first invention, the rotating member is a cast product, and the rib is provided at each of circumferential positions corresponding to a plurality of positions where the extrusion pin contacts in a die-cutting process of casting. It is assumed that a plurality are formed.

  In the case of the above configuration, since the rotating member is a cast product, it is necessary to remove the rotating member from the mold by bringing a plurality of push pins into contact with the rotating member in the mold drawing process. Generally, since the push pin is brought into contact with the end portion of the member, the push pin is also brought into contact with the open end of the cup-shaped member, that is, the open end of the stepped portion. At this time, a rib is formed at a circumferential position corresponding to a position where the push pin of the step portion contacts, and the strength is reinforced. Therefore, even if the pushing force by the pushing pin acts on the stepped portion from the axial direction, the stepped portion is prevented from being damaged.

  According to the present invention, the stepped portion is formed at the opening end of at least one of the fixed-side cup-shaped member and the rotating-side cup-shaped member, and the opening end portions of both the cup-shaped members are overlapped in the axial direction. It is possible to prevent dust and the like from entering the auto tensioner through the gap between the fixed member and the rotating member. At the same time, the step portion has a structure in which stress tends to concentrate on the bent portion. The step portion is formed with a rib extending from the step portion to the circumferential surface of the cup-shaped member. The strength can be improved, and the weight of the fixed member or the rotating member can be reduced compared to a structure that is reinforced by increasing the thickness of the entire cup-shaped member.

  According to the second aspect of the invention, since the rotating member is a cast product, it is necessary to perform die cutting with an extrusion pin. However, since the rib is formed at a position corresponding to a position where the extrusion pin contacts, It is possible to prevent the stepped portion from being damaged when the die is punched by the pin.

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

  1 to 5 show an auto tensioner A according to an embodiment of the present invention. The auto tensioner A is attached to an automobile engine, and a plurality of engine supplements are connected to the engine by, for example, a single belt by an engine output shaft. Used in a serpentine drive device that drives a machine.

  The auto tensioner A has a shaft portion 1a as a basic structure and is fixed to an automobile engine as a fixed body, and the opposite side of the engine on the shaft portion 1a of the fixing member 1 (FIG. 1). And a pulley 2e serving as a belt pressing portion over which a belt (not shown) is movably stretched. In the boss portion 2a, the rotating member 2 is supported by the fixing member 1 so as to be rotatable about the rotation axis X, and the belt pressing direction is applied to the rotation member 2 by the twisting torque about the rotation axis X. And a torsion coil spring 4 that is pivotally biased, and an insert bearing 9 that is interposed between the shaft portion 1a and the boss portion 2a and that imparts rotational resistance to the rotational member 2.

  Specifically, the fixing member 1 is made of a metal such as an aluminum alloy, and a fixed cup-shaped member 1b that opens upward, and an axis that extends upward from the center of the bottom 1c of the fixed cup-shaped member 1b. Part 1a. At the center of the shaft portion 1a, the rotation axis X is located, and a bolt hole 1d is formed in the axial direction. Furthermore, the tip has a smaller diameter for attaching a front plate 13 to be described later. Mounting pieces 6 and 6 for fixing the fixing member 1 to the engine are provided on the outer periphery of the bottom portion 1c so as to protrude outward in the radial direction.

  Further, an insert bearing 9 made of synthetic resin is fitted on the shaft portion 1 a of the fixing member 1. The insert bearing 9 has a substantially cylindrical shape with both upper and lower ends opened. Further, a key portion (not shown) extending in the axial direction is formed in a part of the circumferential direction on the inner peripheral surface of the insert bearing 9, and this key portion is an outer peripheral surface of the shaft portion 1 a of the fixing member 1. Are engaged in key grooves (not shown) formed in the axial direction. Thus, the insert bearing 9 is fixed to the fixing member 1 so as not to rotate.

  The rotating member 2 is made of an aluminum alloy or the like, and includes a rotating cup-shaped member 2b that opens to the engine side (the lower side in FIG. 1 and hereinafter simply referred to as the lower side), and the rotating cup shape. A boss 2a extending downward from the center of the bottom 2c of the member 2b, a pulley mounting portion 2d extending radially outward from the rotating cup-shaped member 2b, and a pulley provided on the upper end of the pulley mounting portion 2d 2e. The boss 2a is externally fitted on the shaft 1a of the fixing member 1 via the insert bearing 9 so as to be rotatable. The inner and outer diameters of the rotating cup-shaped member 2b are substantially the same as the inner and outer circumferences of the fixed cup-shaped member 1b. The pulley 2e is rotatably provided with respect to the pulley mounting portion 2d via a ball bearing 2f provided at the tip of the pulley mounting portion 2d, and a belt is stretched around the outer periphery thereof. .

  As shown in FIG. 1, an overlap portion 20 is formed at the opening end of the rotating cup-shaped member 2b as a stepped portion that overlaps the opening end portion of the fixed-side cup-shaped member 1b in the axial direction. ing. That is, when viewed in the radial direction, the opening end of the fixed cup-shaped member 1b and the opening end of the rotating cup-shaped member 2b overlap. The overlap portion 20 is bent and expanded in diameter in a longitudinal sectional view, and the inner peripheral diameter thereof is larger than the outer diameter of the opening end portion of the fixed cup-shaped member 1b. And the labyrinth L bent by the longitudinal cross-sectional view is formed in the clearance gap between the fixed side cup-shaped member 1b and the rotation side cup-shaped member 2b.

  Further, as shown in FIGS. 1 to 3, ribs 21, 21,... Extending in the axial direction from the overlap portion 20 are formed on the outer peripheral surface 2 h of the rotating cup-shaped member 2 b. The ribs 21, 21,... Are formed in a substantially triangular shape so as to fill an angle formed by the outer upward surface of the overlap portion 20 and the outer peripheral surface 2h of the rotating cup-shaped member 2b. A plurality of cup-shaped members 2b are provided at predetermined intervals in the circumferential direction.

  Further, the rotating member 2 is a die-cast product. As shown in FIG. 4, when the die-cast die is released, the opening pin P of the rotating cup-shaped member 2b, that is, the overlap portion 20 is pushed from the lower side. Push it out of the mold. As shown in FIG. 5, the push-out pins P, P,... Abut on a plurality of locations in the circumferential position of the rotating cup-shaped member 2b and the pulley mounting portion 2d. The ribs 21, 21,... Correspond to the positions where the push pins P, P,... Abut at the circumferential position of the rotating cup-shaped member 2b when the die-casting is released (see FIGS. 3 and 5). Is formed. At the time of die-casting, the push-out force of the push-out pins P, P,... Acts upward in the axial direction, and stress tends to concentrate on the bent portion of the overlap portion 20. However, since the overlap portion 20 is reinforced by the ribs 21, 21,..., The overlap portion 20 is not damaged due to insufficient strength.

  The rotating member 2 is attached to the shaft portion 1a of the fixing member 1 by a front plate 13 as a pressing plate via a thrust washer 14 as a friction plate on the upper end surface 2g of the bottom 2c of the rotating cup-shaped member 2b. It has been.

  The thrust washer 14 is made of a resin, and is formed of, for example, a polyamide resin such as polyether ether kent (PEEK), a clutch facing material, a brake lining material, or a brake pad material.

  The front plate 13 has a disk shape having an outer peripheral diameter larger than the outer peripheral diameter of the thrust washer 14, and is attached to the tip of the shaft portion 1a of the fixing member 1 by caulking or the like. At this time, the thrust washer 14 is completely covered with the front plate 13 when viewed from above in the direction of the rotational axis X.

  A spring support 3 is externally fitted to the boss 2a of the rotating member 2 so as to be slidable with respect to the boss 2a. The spring support 3 has a cylindrical shape with both upper and lower ends opened, and is disposed with a predetermined clearance between the boss portion 2a. Further, the spring support 3 has an outward flange-shaped flange 3a at the lower opening edge thereof, and the spring support 3 cannot rotate to the bottom 1c of the fixed cup-shaped member 1b at the flange 3a. It is fixed to.

  The torsion coil spring 4 is disposed on the inner side of the fixed cup-shaped member 1b and the rotating cup-shaped member 2b and is externally fitted to the boss 2a and the spring support 3 of the rotating member 2. Yes. The torsion coil spring 4 is a right-handed winding, and is disposed between the bottom 1c of the fixed cup-shaped member 1b and the bottom 2c of the rotating cup-shaped member 2b in a compressed state in the axial direction. Yes. The thrust washer 14 is pressed against the front plate 13 by the expansion / contraction restoring force of the torsion coil spring 4. Furthermore, the torsion coil spring 4 has a rotating side tongue (not shown) at the upper end thereof locked to the rotating side cup-shaped member 2b in a state where the coil diameter is reduced, while the fixed side at the lower end thereof. A tongue (not shown) is locked to the fixed-side cup-shaped member 1b. Thus, the rotating member 2 is urged to rotate in the belt pressing direction by the twisting torque in the direction of increasing the coil diameter. Further, a part of the circumferential direction of the spring support 3 is pressed radially inward by the reaction force with the torsion torque on the fixed side tongue as a fulcrum, and is pressed against the boss portion 2a of the rotating member 2. Thus, the boss 2a is also pressed inward in the radial direction and pressed against the insert bearing 9. Thus, the turning member 2 is given a turning resistance by the insert bearing 9.

  As described above, in the auto tensioner A, the fixing member 1 is fixed to the engine via the mounting pieces 6 and 6, and a belt is stretched around the pulley 2 e of the rotating member 2. Since the rotating member 2 is urged to rotate in the belt pressing direction with respect to the fixing member 1 by the twisting torque of the torsion coil spring 4, a certain tension is applied to the belt.

  When the belt tension decreases, the rotating member 2 and the pulley 2e are tilted in the direction of increasing the belt tension by the torsion torque of the torsion coil spring 4, and the belt tension is adjusted to be constant. To do. On the other hand, when the belt tension increases, the rotating member 2 and the pulley 2e are tilted in the direction of decreasing the belt tension against the twisting torque of the torsion coil spring 4, and the belt tension becomes constant. Adjust as follows.

  Further, when vibration or impact is applied to the belt, the vibration or impact is transmitted to the boss portion 2a of the rotating member 2. The boss portion 2a is transmitted to the spring support 3 and the insert bearing 9, respectively. They are in pressure contact, and a sliding resistance is generated by sliding between them. Vibrations and impacts applied to the belt are absorbed and damped by the rotational resistance. Furthermore, since the boss portion 2a is pressed against the thrust washer 14 by the expansion / contraction restoring force of the torsion coil spring 4, vibration and impact are absorbed and attenuated by the rotational resistance.

  In this way, the belt tension is kept constant even if the belt tension changes due to environmental changes such as temperature changes and aging of the belt, etc., and even if vibration or impact is applied to the belt, it is absorbed and attenuated. be able to.

  At this time, the opening end portions of the fixed-side cup-shaped member 1b and the rotating-side cup-shaped member 2b are not in contact with each other in order to avoid sliding and wearing, and the fixed-side cup-shaped member 1b. And a rotating cup-shaped member 2b. Therefore, an overlap portion 20 is formed at the opening end of the rotating cup-shaped member 2b, and a labyrinth L is formed in the gap. The labyrinth L can prevent dust and the like from entering the auto tensioner A through the gap. As a result, the lifetime of the insert bearing 9 and the like located inside the auto tensioner A can be improved.

  Therefore, according to the auto tensioner A, the overlap portion 20 is formed at the opening end of the rotating cup-shaped member 2b, and the opening end of the fixed cup-shaped member 1b and the opening of the rotating cup-shaped member 2b. By forming the labyrinth L in the gap with the end, it is possible to prevent dust and the like from entering the auto tensioner A from the gap.

  At this time, the overlap portion 20 formed on the rotating cup-shaped member 2b overlaps so as to cover the opening end portion of the fixed-side cup-shaped member 1b from the outer periphery. Intrusion can be effectively prevented.

  In addition, the overlap portion 20 is bent and expanded in diameter in a longitudinal sectional view, and has a structure in which stress is easily concentrated on the bent portion. Are formed, the strength of the overlap portion 20 can be improved.

  Further, the rotating member 2 has a structure in which the overlap portion 20 and the ribs 21, 21,... Are combined, so that it is reinforced by increasing the thickness of the entire cup-shaped member. Thus, the weight of the rotating member 2 can be reduced.

  In particular, since the rotating member 2 is a die-cast product, it is necessary to remove the die by the extrusion pins P, P,..., But the ribs 21, 21,... Correspond to the positions where the extrusion pins P, P,. Since it is formed at a position in the circumferential direction, it is possible to prevent the overlap portion 20 from being damaged when the die is punched by the push pins P, P,. At the same time, ribs 21, 21,... Are formed at the minimum necessary positions for reinforcement, and the rotating member 2 can be reduced in weight efficiently.

<< Other Embodiments >>
The present invention may be configured as follows with respect to the above embodiment.

  In the said embodiment, although the structure which forms the overlap part 20 in the opening end of the rotation side cup-shaped member 2b is employ | adopted, it is not restricted to this. For example, you may further provide the overlap part which overlaps with the rotation side cup-shaped member 2b in the axial direction inside the said fixed-side cup-shaped member 1b. In that case, the rib is preferably provided on the inner peripheral surface of the fixed cup-shaped member 1b.

It is sectional drawing which cut | disconnected the rotational axis of the auto tensioner which concerns on this embodiment, and the plane which passes along the rotational axis of a pulley. It is a front view of the rotation member concerning this embodiment. It is a top view of a rotation member. It is explanatory drawing explaining the contact position of an extrusion pin. Bottom view of rotating member and push pin

Explanation of symbols

A Auto tensioner P Extrusion pin 1 Fixing member 1b Fixed side cup-shaped member 2 Rotating member 2b Rotating side cup-shaped member 2e Pulley (belt pressing part)
2h Outer peripheral surface 20 Overlap part (step part)
21 Ribs

Claims (2)

A fixed member having a fixed-side cup-shaped member that is fixed to the fixed body and opens to the opposite side of the fixed body;
A rotation-side cup-shaped member that opens to the fixed body side and is coaxially connected to the axis of the fixed-side cup-shaped member and is rotatably attached to the fixed member; A rotation member having a belt pressing portion that rotates around the belt so that the belt can travel.
At least one of the fixed-side cup-shaped member and the rotating-side cup-shaped member has a stepped portion at the opening end thereof, and the opening end portions of the two cup-shaped members overlap in the axial direction. And
An auto tensioner, wherein a rib extending in the axial direction from the stepped portion is provided on a peripheral surface of the cup-shaped member in which the stepped portion is formed. The auto tensioner according to claim 1,
The rotating member is a cast product,
The auto-tensioner is characterized in that a plurality of the ribs are formed at respective circumferential positions corresponding to a plurality of positions where the extrusion pins abut in the die-cutting step of casting.

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