JP7112941B2 - auto tensioner - Google Patents

Description

The present invention relates to an auto-tensioner for automatically maintaining proper belt tension.

2. Description of the Related Art Conventionally, an auto-tensioner has been employed as a mechanism for keeping belt tension constant in accessory drive belt systems and camshaft drive belt systems for automobile engines.

The auto tensioner 161 is generally fixed to an engine block (not shown) as shown in FIG. An arm 164, a cylindrical sliding portion 168 interposed between the shaft portion 162 and the arm 164, and a rolling bearing 166 that is rotatably attached to the arm 164 about an axis R1 parallel to the shaft portion 162. a coil spring 167 that urges the arm 164 to rotate in one direction; and a plate-shaped sliding portion 169 that functions as a damping portion that damps the swinging motion of the arm 164, and the like.

The auto tensioner 161 is a component that adjusts the tension of the belt wound around the pulley 165 . As the tension of the belt increases and decreases, the pulley 165 and the arm 164 supporting the pulley 165 swing around the axis R1, but the swing is damped by the damping section. As a result, swinging of the pulley 165 and the arm 164 due to vibration and impact from the belt can be damped.

By the way, in the so-called main engine auto tensioner used in the camshaft drive belt system, the belt system is meshing transmission, and in order to suppress the deviation of the valve timing, it is better not to rotate the arm so much. For this reason, for example, as in Patent Document 1, there is a demand for a compact structure in which the swinging range of the arm is reduced. In the auto tensioner of Patent Document 1, a sliding member functioning as a slide bearing is interposed between an arm (pulley support) and a fixed-side shaft. The sliding member is configured by integrating a cylindrical sliding portion arranged between the boss portion and the shaft portion of the arm and an annular plate-shaped sliding portion arranged on the end surface of the arm on one end side. is.

Japanese Utility Model Laid-Open No. 6-10645 JP-A-2002-5252

In particular, the camshaft drive belt system is generally covered with a cover in order to prevent foreign matter, water, and grease from adhering to each component (particularly, the timing belt). Therefore, foreign matter such as dust floating in the inner space of the cover is less than that in the outer space of the cover. is possible. In addition, water droplets that enter the cover through gaps adhere to metal members such as coil springs, producing corrosion products (rust) that eventually separate from the surface and float in the inner space of the cover, creating foreign matter. sometimes.

Here, in an auto tensioner having a sliding member as disclosed in Patent Document 1, if the above-described foreign matter enters the periphery of the sliding member, wear of the sliding surface of the sliding member progresses locally. In addition, since the pulley and the shaft are not arranged coaxially, when the arm swings, a rotational moment acts in the direction of tilting the arm due to the belt load. As a result, uneven wear first occurs on the outer peripheral edge of the plate-shaped sliding portion of the sliding member, and then uneven wear also occurs on the cylindrical sliding portion. Such partial wear causes a gap between the sliding member and the mating member, making it easier for foreign matter to enter.

In this respect, Patent Document 1 does not particularly disclose a configuration for preventing foreign matter from entering the vicinity of the plate-shaped sliding portion of the sliding member.

Patent Document 2 discloses an auto tensioner having a configuration for preventing foreign matter from entering the end surface of the arm and the vicinity of the boss portion. In the auto tensioner disclosed in Patent Document 2, an arm is rotatably supported by a shaft portion (an arm support portion of a support shaft member) through a cylindrical bush. A friction plate is attached to a recess formed in the end face of the arm. On the other hand, a friction plate pressing member is fixed to the fixed-side shaft portion (arm supporting portion) with a bolt, and the friction plate pressing member is pressed against the friction plate. Further, the friction plate pressing member is integrally provided with a seal member having a planar size one size larger than that of the friction plate pressing member. That is, in Patent Document 2, the seal member is attached to the fixed-side shaft portion.

In the auto tensioner disclosed in Patent Document 2, the seal member can prevent foreign matter from entering the recess in which the friction plate is accommodated and the periphery of the bush. However, in the structure of Patent Document 2 in which the seal member is attached to the fixed-side shaft portion, the friction plate pressing member is essential for installing the seal member, which is not preferable from the viewpoint of increasing the number of parts.

For example, in the structure of the auto tensioner disclosed in Patent Document 2, it is possible to omit the friction plate pressing member by substituting the head portion of the bolt fixed to the shaft portion as the pressing member only to press the friction plate. However, if the friction plate pressing member is omitted, the sealing member cannot be installed as it is. It is also unreasonable to use a bolt with an extremely large head to attach the seal member. Therefore, a dedicated member for installing the seal member is required.

SUMMARY OF THE INVENTION An object of the present invention is to prevent foreign matter from entering a gap between an end face of an arm on one end side and a pressing member, thereby ensuring durability of an auto tensioner.

An auto tensioner according to the present invention comprises a base fixed to an engine block to which a shaft is attached, an arm rotatably supported by the base via the shaft, and an axis parallel to the shaft. a pulley rotatably attached to the belt and contactable with the belt; and a rolling bearing interposed between the arm and the pulley and having a holding chamber for accommodating rolling elements between an inner ring and an outer ring; a cylindrical sliding portion arranged between the boss portion of the arm and the shaft portion; and a plate-like sliding portion arranged between the end surface of the arm and a pressing member connected to the shaft portion, the sliding member rotating integrally with the arm, and the sliding member arranged around the shaft portion. a coil spring for urging the arm to rotate in one direction with respect to the base; a plate-like sliding portion provided on the arm so as not to rotate relative to the arm; a sealing member arranged to cover a gap between the end face and the pressing member.

According to the above configuration, the gap between the plate-like sliding portion of the sliding member and the arm and the gap between the plate-like sliding portion and the pressing member are covered with the seal member, which is relatively simple. is less likely to enter the gap, and the durability of the auto tensioner is improved.

Also, the seal member is provided on the arm so as not to rotate relative to it, and rotates integrally with the arm. Therefore, unlike the case where the sealing member is provided on the fixed side as in the above-mentioned Patent Document 2, there is no difficulty in installing the sealing member, and there is no need to add a dedicated member for supporting the sealing member.

In the auto tensioner of the present invention, it is preferable that the seal member is sandwiched between the plate-like sliding portion and the end surface of the arm on the one end side.

According to the above configuration, the seal member, the arm, and the plate-like sliding portion rotate integrally. In addition, since the seal member is sandwiched between the plate-shaped sliding portion and the end surface of the arm, the opening of the gap between the plate-shaped sliding portion and the end surface of the arm is reliably closed.

In the auto tensioner of the present invention, it is preferable that the end surface of the arm on the one end side and the facing surface of the seal member facing the end surface are provided with concave portions and convex portions so as to be fitted to each other.

According to the above configuration, the seal member can be configured to be non-rotatable with respect to the arm.

In the auto tensioner of the present invention, it is preferable that the sealing member covers the opening of the holding chamber of the rolling bearing on the one end side.

According to the above configuration, the sealing member can also prevent foreign matter from entering the holding chamber of the rolling bearing.

In the auto tensioner of the present invention, the sliding member is formed with a slit extending in the axial direction and has a C-shaped cross section. It is preferably larger than the inner diameter of the boss portion of the arm.

According to the above configuration, the sliding member is attached to the boss portion of the arm in a slightly reduced diameter state. Therefore, the cylindrical sliding portion can be brought into pressure contact with the inner surface of the boss portion of the arm by the self-elastic restoring force of the sliding member in the radially expanding direction, so that the sliding member cannot rotate relative to the arm more reliably. becomes. Thereby, the inner surface of the cylindrical sliding portion and the one end surface of the plate-shaped sliding portion can more reliably function as sliding surfaces of the sliding member.

In the auto tensioner of the present invention, the base material of the sliding member is made of metal, and the inner surface of the cylindrical sliding portion and the end surface of the plate-like sliding portion on the one end side are formed from the base material. It is also preferable that both are made of a synthetic resin material having a surface characteristic of a low coefficient of friction.

According to the above configuration, wear of the sliding surface of the sliding member can be suppressed, and the durability of the sliding member can be ensured.

In the auto tensioner of the present invention, it is preferable that the coil spring is compressed in the axial direction of the shaft portion.

According to the above configuration, the coil spring presses the arm by the elastic restoring force of the shaft in the axial direction. Since the plate-shaped sliding portion of the sliding member exists between the boss portion of the arm and the pressing member, the elastic restoring force of the coil spring in the axial direction of the shaft portion is applied to the plate-shaped sliding portion. As a result, a frictional force is generated between the plate-like sliding portion and the pressing member, and the plate-like sliding portion functions as a damping member that dampens the swinging motion of the arm.

Since the plate-like sliding portion is strongly pressed against the pressing member, the degree of uneven wear of the plate-like sliding portion also increases. Therefore, it is very significant to provide a sealing member in order to prevent foreign matter from entering the vicinity of the plate-shaped sliding portion. Further, when a structure in which a portion of the seal member is disposed between the plate-shaped sliding portion and the end surface of the arm is adopted, the seal member is strongly clamped by the restoring force of the coil spring. The effect of integrating the shape sliding portion and the sealing member is enhanced.

In the auto tensioner of the present invention, it is preferable that the seal member includes a portion made of an elastic material.

According to the above configuration, the sealing member is likely to come into close contact with the periphery of the plate-shaped sliding portion, so that the sealing effect is enhanced.

In the auto tensioner of the present invention, it is preferable that a portion of the seal member formed of the elastic member is in annular contact with both the end surface of the arm on the one end side and the pressing member.

According to the above configuration, a portion of the sealing member made of an elastic material contacts both the end surface of the one end side of the arm and the pressing member, whereby the opening of the gap between the plate-shaped sliding portion and the pressing member and the The opening of the gap between the plate-like sliding portion and the end face on the one end side of the boss portion of the arm can be reliably closed.

In addition, if a portion of the sealing member made of an elastic material is in contact with both the end surface of the arm and the pressing member, the pressing member is in contact only with the plate-like sliding portion. and the pressing member are relieved. As a result, it is possible to suppress the generation of abnormal noise when the plate-like sliding portion and the pressing member come into frictional contact with each other.

In the auto tensioner of the present invention, it is preferable that the seal member has a protrusion that makes line contact with the pressing member.

According to the above configuration, the contact area between the sealing member and the pressing member is reduced, and the contact resistance between the sealing member and the pressing member is reduced, so that the sealing member can more reliably rotate together with the arm.

In the auto tensioner of the present invention, it is preferable that all of the sealing members are made of an elastic material.

According to the above configuration, the manufacturing cost can be reduced as compared with the case where the seal member includes a portion not made of an elastic material.

In the auto tensioner of the present invention, it is preferable that a plurality of convex ribs are formed along the radial direction of the axis of the shaft portion on the surface of the sealing member on the one end side.

According to the above configuration, since the rigidity of the seal member in the radial direction of the axis of the shaft portion is increased, the seal member is more reliably fitted and supported in contact with the arm so as not to be relatively rotatable, and is integrally supported with the arm. It can rotate.

In the auto tensioner of the present invention, it is preferable that the arm is eccentrically supported by the base, and the pulley is attached to the outer peripheral side of the arm.

The above configuration is suitable for a camshaft drive belt system in which it is better not to rotate the arm to a large extent.

According to the present invention, in the auto tensioner, it is possible to prevent foreign matter from entering the gap between the end surface of the arm on the one end side and the pressing member, thereby ensuring the durability of the auto tensioner.

1 is a schematic configuration diagram of a camshaft drive belt system using an auto tensioner according to an embodiment of the present invention; FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1; 1 is a front view of an auto tensioner according to this embodiment; FIG. 1 is a side view of an auto tensioner according to this embodiment; FIG. It is a bottom view of the auto tensioner which concerns on this embodiment. FIG. 5 is a cross-sectional view taken along line BB of FIG. 4 (FIG. 2); 2A and 2B are a two-sided view (a front view and a bottom view) of the sliding member according to the present embodiment, and a cross-sectional view of the front view of the sliding member taken along the line AA. FIG. 2 is a cross-sectional view (a cross-sectional view taken along line AA in FIG. 1) of a state in which a fastening bolt is inserted through the auto tensioner according to the present embodiment; FIG. 2 is an enlarged cross-sectional view of a main part of an auto tensioner according to a modification of the invention (a cross-sectional view taken along the line AA in FIG. 1); FIG. 3 is a cross-sectional view of an auto tensioner according to a conventional example; (Cross-sectional view taken along line AA in FIG. 1)

Next, an embodiment of the invention will be described. As shown in FIG. 1, in a camshaft drive belt system 1, one belt 3 is wound around an auto tensioner 2 assembled to an engine block, one drive pulley, and two driven pulleys. It is Since the belt 3 is a meshing transmission belt that drives a camshaft of an automobile engine, an auto tensioner with a compact structure that does not allow the arm to rotate so much is preferably used.

As shown in FIGS. 2 to 6, the auto tensioner 2 of the present embodiment includes a base 7 fixed to an engine block, to which a shaft portion 4 is attached, and a base 7 that is rotatable with respect to the base 7 via the shaft portion 4. A supported arm 8, a pulley 9 attached to the arm 8 and capable of coming into contact with the belt and rotatable about an axis parallel to the shaft 4, and a slide rotating integrally with the arm 8. A moving member 12, a coil spring 11 disposed around the shaft portion 4 and biasing the arm 8 to rotate in one direction with respect to the base 7, and a rolling bearing 10 disposed between the arm 8 and the pulley 9. and a seal member 13 provided on the arm 8 so as not to rotate relative to it. In addition, let the upper side in FIG. 2 be one end side, and let the lower side be the other end side. Let the end face on the one end side be the one end face, and let the end face on the other end side be the other end face. Moreover, let the up-down direction in FIG. 2 be the front-back direction.

(Shaft 4)
As shown in FIG. 2 , the shaft portion 4 is a post of the auto tensioner 2 extending in the axial direction, and the axis R, which is the axis line of the shaft portion 4 , is eccentric with respect to the center 91 of the pulley 9 . As a result, the pulley 9 and the arm 8 swing around the axis R as the belt tension increases or decreases. A flange is formed integrally with the shaft portion 4 on the other end side of the shaft portion 4 . Further, the outer peripheral surface of the shaft portion 4 is formed parallel to the axial direction. According to this, the size of the auto tensioner 2 can be reduced in the radial direction.

A bolt insertion hole 52 extending in the axial direction is formed in the shaft portion 4 at a position eccentric to the axis R, as shown in FIG. As shown in FIG. 8, the fastening bolt 5 is inserted into the bolt insertion hole 52 to fix the shaft portion 4 to the engine block. As shown in FIG. 3, the center 51 of the bolt is eccentric with respect to the axis R when the shaft portion 4 is fixed to the engine block.

(Holding member 6)
As shown in FIG. 2, the pressing member 6 is separately formed on one end side of the shaft portion 4 opposite to the engine block, and is in contact with one end surface of the shaft portion 4 so as not to rotate relative to it. Note that the pressing member 6 may be formed integrally with the shaft portion 4 . The pressing member 6 is preferably formed in a substantially hexagonal shape when viewed from one end side. As a result, the shaft portion 4 can be rotated around the fastening bolts 5 temporarily fixed to the engine block by gripping the side surfaces of the substantially hexagonal shape with a tool such as a spanner. A surface of the pressing member 6 on the other end side is formed as an annular flat surface along the direction perpendicular to the axis R. As shown in FIG. As a result, it becomes parallel to one end surface of the boss portion 83 of the arm 8 and reliably contacts the plate-like sliding portion 122 over a wide area. The pressing member 6 is made of carbon steel (S45C), and is surface-hardened by nitrocarburizing in order to increase the wear resistance of the surface of the other end side that slides on the plate-shaped sliding portion 122 of the sliding member 12. are applied. It should be noted that the configuration of the material of the pressing member 6 may not be the configuration described above.

(Base 7)
As shown in FIG. 2, the base 7 is a separate member from the shaft portion 4 and is provided coaxially with the axis R of the shaft portion 4 . The base 7 is connected to a base inner tubular portion 71 and a base outer tubular portion 72 that face each other in the radial direction, and to an edge of the other end of the base inner tubular portion 71 and an edge of the other end of the base outer tubular portion 72 . and an annular bottom portion 73 . The base inner cylindrical portion 71 and the base outer cylindrical portion 72 are provided coaxially with the axis R of the shaft portion 4 . A bottom portion 73 of the base 7 is formed on a flat surface parallel to the radial direction. The bottom portion 73 of the base 7 and the surface on one end side of the flange formed on the other end side of the shaft portion 4 are in contact with each other, and the base 7 is maintained until the shaft portion 4 is fixed to the engine block. It is configured to be rotatable relative to the shaft portion 4 .

As shown in FIG. 8, the base 7 is fixed to the engine block together with the shaft portion 4 by fastening bolts 5 so as not to rotate relative to each other. However, before the auto tensioner 2 is fixed to the engine block, the base 7 is configured to be rotatable relative to the shaft portion 4, and its position in the circumferential direction is fixed with respect to the engine block (rotation stop). is preferred. As a result, the shaft portion 4 can be rotated around the fastening bolt 5 in a state where the auto tensioner 2 is temporarily fixed to the engine block, and the shaft portion 4 can be arranged at an appropriate position. The material of the base 7 may be, for example, cold-rolled steel plate (SPCC). In this case, the surface is preferably galvanized for rust prevention.

The anti-rotation portion 74 formed on the base 7 is, as shown in FIG. and a locking portion 274 extending further rearward from the distal end portion thereof while changing its orientation by approximately 90°. When the auto tensioner 2 is assembled to the engine block, the engaging portion 274 of the detent portion 74 is engaged with an elongated recessed groove formed in one end face of the engine block to attach the base 7 to the engine block. Stop it from rotating. In addition, as shown in FIGS. 3 to 6, the tip of the extension portion 174 is provided with an arc-shaped notch.

In addition, as shown in FIGS. 5 and 6, one base holding groove 75 is formed in the base outer cylindrical portion 72 . This is a groove for fitting and holding a bent portion of the other end portion 113 of the coil spring 11 housed in the spring housing chamber 111 .

(Arm 8)
As shown in FIG. 2, the arm 8 is eccentrically supported by the base 7, and includes a boss portion 83 arranged on one end side of the base 7, an arm inner cylindrical portion 81 extending rearward from the boss portion 83, and an arm inner cylinder portion 81 extending rearward from the boss portion 83. An arm outer tubular portion 82 formed apart from the arm inner tubular portion 81 radially outwardly so as to be parallel to the tubular portion 81 , and an annular extension portion 84 extending radially outward from the boss portion 83 . It has The extension part 84 of the arm 8 extends to near the outer surface of the outer ring 102 of the rolling bearing 10 . For example, the longitudinal clearance between one end surface of the extension portion 84 of the arm 8 and the other end surface of the outer ring 102 of the rolling bearing 10 may be approximately 0.3 mm. Further, the arm inner tubular portion 81 extends radially outward of the base inner tubular portion 71 so as to axially overlap with the base inner tubular portion 71 . For example, the radial gap between the inner surface of the arm inner tubular portion 81 and the outer surface of the inner tubular portion of the base 7 may be approximately 0.3 mm. The arm inner tubular portion 81 and the arm outer tubular portion 82 are preferably provided coaxially with the shaft portion 4 in the same manner as the inner tubular portion and the outer tubular portion of the base 7 . The extending portion 84 of the arm 8 is preferably formed on a flat surface parallel to the radial direction.

As shown in FIG. 2, a shaft portion insertion hole 41 is formed radially inside the boss portion 83 of the arm 8 at a position eccentric with respect to the center 91 of the pulley 9. A shaft portion 4 is inserted through 12 . The arm 8 is rotatably supported relative to the base 7 via the shaft portion 4 . Arm 8 is a metal part made of aluminum alloy casting. It should be noted that the arm 8 does not have to be a metal part made of cast aluminum alloy. Further, the arm 8 swings around the axis R of the shaft portion 4 as the tension of the belt 3 increases or decreases.

As shown in FIG. 2, a concave portion 15 is formed in a portion of one end surface of the boss portion 83 of the arm 8 so as to be able to be fitted with a convex portion 14 formed in at least a portion of the other end surface of the seal member 13 . It is The cross section of the recess 15 of the arm 8 is circular. A convex portion may be formed on a part of one end surface of the boss portion 83 of the arm 8 .

As shown in FIG. 6 , one arm holding groove 86 is formed in the arm outer cylindrical portion 82 . The arm holding groove 86 is a groove for fitting and holding a bent portion of the one end portion 112 of the coil spring 11 housed in the spring housing chamber 111 .

As shown in FIGS. 3 to 6, the arm outer cylindrical portion 82 is provided with an indicator portion 85 extending radially outward and having a tapered tip end. The projection radius, which is the length of the indicator portion 85 from the axis R, is preferably substantially equal to the projection radius, which is the length from the axis R of the anti-rotation portion 74 projecting from the base 7 . The indicator portion 85 of the arm 8 and the anti-rotation portion 74 of the base 7 have the function of marking the arm 8 and the base 7 in the circumferential direction about the axis R. As shown in FIG. The function of the countermark will be explained later.

(rolling bearing 10 and pulley 9)
As shown in FIG. 2, the rolling bearing 10 is interposed between the arm 8 and the pulley 9, and has a plurality of balls between an inner ring 101 and an outer ring 102 which are two concentrically arranged ring-shaped members. It is a ball bearing having an annular holding chamber 103 in which rolling elements 105 are accommodated. In this embodiment, a sealed ball bearing is employed in which grease is sealed in a holding chamber 103 in which rolling elements 105 are accommodated, and annular sealing materials (not shown) are arranged on both sides of a plurality of balls. The inner ring 101 of the rolling bearing 10 is closely fixed to the outer peripheral surface of the boss portion 83 of the arm 8 , and the outer ring 102 is closely fixed to the inner peripheral surface of the pulley 9 . The pulley 9 is attached to the outer peripheral side of the arm 8 and supported by the boss portion 83 of the arm 8 via the rolling bearing 10 so as to be relatively rotatable. The pulley 9 rotates around the belt 3 for driving the camshaft. As the tension of the belt 3 increases and decreases, the pulley 9 swings about the axis R of the shaft portion 4 instead of the center 91 of the pulley 9 which is the center of rotation of the pulley 9 .

(Coil spring 11)
As shown in FIG. 2, the coil spring 11 is formed by spirally winding a metal wire, and is accommodated in the spring accommodation chamber 111 while being compressed in the axial direction of the shaft portion 4 . The spring housing chamber 111 is surrounded by the arm outer cylinder portion 82 , the base outer cylinder portion 72 , the boss portion 83 of the arm 8 , the bottom portion 73 of the base 7 , the arm inner cylinder portion 81 , and the base inner cylinder portion 71 . space. As shown in FIGS. 5 and 6, the coil spring 11 has one end engaged with the arm 8 and the other end engaged with the base 7, and urges the arm 8 to rotate in one direction with respect to the base 7. do. The coil spring 11 is set to contract when the tension of the belt 3 increases and the arm 8 rotates in the direction of loosening the belt 3 . Specifically, the coil spring 11 is housed in the spring housing chamber 111 in a state of being twisted in a diameter-reducing direction during assembly. A rear end portion of the coil spring 11 is bent and held in a base holding groove 75 formed in the base 7 . Also, the front end of the coil spring 11 is similarly bent and held in an arm holding groove 86 formed in the arm 8 .

The coil spring 11 preferably has a constant diameter over its entire length when no external force is applied to the auto tensioner 2 . The coil spring 11 may be formed, for example, by winding an oil-tempered spring wire with a round cross-section having a diameter of about 2 mm counterclockwise.

(Sliding member 12)
As shown in FIG. 2, the sliding member 12 is formed by integrally forming a cylindrical sliding portion 121 and a plate-shaped sliding portion 122 via a connecting portion 123 . The cylindrical sliding portion 121 is arranged between the shaft portion 4 and the boss portion 83 of the arm 8 . The plate-like sliding portion 122 is arranged between the pressing member 6 and one end surface of the boss portion 83 of the arm 8 . The cylindrical sliding portion 121 is arranged along a direction substantially parallel to the axis R, and the inner surface of the cylindrical sliding portion 121 is a sliding surface with the outer surface of the shaft portion 4 . The plate-like sliding portion 122 is arranged along a direction substantially orthogonal to the axis R, and one end surface of the plate-like sliding portion 122 is a sliding surface with the other end surface of the pressing member 6 . The thicknesses of the cylindrical sliding portion 121, the plate-like sliding portion 122, and the connecting portion 123 are all approximately equal, and may be, for example, approximately 1 mm.

As shown in FIGS. 6 and 7, the sliding member 12 is formed with a slit 124 extending in the axial direction. The slit 124 forms a linearly continuous circumferential opening gap from the other end surface of the cylindrical sliding portion 121 to the edge of the outer peripheral edge of the plate-shaped sliding portion 122 via the connecting portion 123 . there is That is, the slit 124 has a C-shaped cross section perpendicular to the axial direction of the shaft portion 4 . For example, the width of the slit 124 may be approximately 1 mm when no external force is applied to the auto tensioner 2 . Further, when there is no load on the sliding member 12 , the outer diameter of the cylindrical sliding portion 121 of the sliding member 12 is larger than the inner diameter of the boss portion 83 of the arm 8 .

Since the coil spring 11 is compressed in the axial direction of the shaft portion 4, an elastic restoring force in the axial direction of the shaft portion 4 acts, and the plate-like sliding portion 122 is pressed by the arm 8 toward one end. As a result, friction is generated between the pressing member 6 and the arm 8 , and the plate-shaped sliding portion 122 functions as a damping portion that dampens the rocking motion of the arm 8 . Further, the tubular sliding portion 121 functions as a sliding bearing. When the coil spring 11 is not compressed in the axial direction of the shaft portion 4 , the elastic restoring force of the shaft portion 4 in the axial direction does not work. The plate-shaped sliding portion 122 of the sliding member 12 functions as a slide bearing without being pressed toward one end.

The base material of the sliding member 12 is made of metal, and the inner surface of the cylindrical sliding portion 121 and the end surface of the plate-like sliding portion 122 on one end side, which are the sliding surfaces, have lower friction than the base material. It is made of a synthetic resin material with modulus surface properties. This synthetic resin material preferably has self-lubricating properties. Specifically, regarding the synthetic resin material that forms the sliding surface, the synthetic resin that is the main component includes thermoplastic resins such as polyamide, polyacetal, polytetrafluoroethylene, polyphenylene sulfide, and ultra-high molecular weight polyethylene, or A thermosetting resin such as phenol is preferably used. A solid lubricant may or may not be blended with the synthetic resin that is the main component. In addition, reinforcing fibers may or may not be blended into the synthetic resin that is the main component.

As the sliding member 12, for example, the base material is a steel strip, and the inner surface of the cylindrical sliding portion 121 and the end surface of the plate-like sliding portion 122 on one end side, which are the sliding surfaces, are made of polytetrafluoroethylene (PTFE). A multi-layered metal bearing (LFF type manufactured by Oiles Industry Co., Ltd.) coated with a synthetic resin containing as a main component can be employed. This sliding surface has self-lubricating sliding properties and has surface properties with a lower coefficient of friction than the base material (steel strip).

(Seal member 13)
As shown in FIG. 2, the seal member 13 is a flat annular member, and has a fitting hole formed in the center thereof. The shaft portion 4 and the cylindrical sliding portion 121 of the sliding member 12 are inserted through this fitting hole. The diameter of this fitting hole is substantially equal to the diameter of the boundary portion between the plate-like sliding portion 122 and the connecting portion 123 in the sliding member 12, thereby preventing the seal member 13 from rattling in the radial direction.

As shown in FIG. 2, the seal member 13 is arranged on one end side of the shaft portion 4 so as to cover one end face of the arm 8 and an opening 104 on one end side of the holding chamber 103 of the rolling bearing 10 from one end side. ing. For example, the longitudinal gap between one end face of the outer ring 102 of the rolling bearing 10 and the other end face of the seal member 13 may be approximately 0.3 mm. The radially inner end portion of the seal member 13 is annularly sandwiched between the plate-shaped sliding portion 122 of the sliding member 12 and one end surface of the arm 8, and radially outside the sandwiched portion, The protrusion 131 of the seal member 13 and the pressing member 6 are in annular line contact. At this time, the line contact means that the contact surface between the seal member 13 and the pressing member 6 has a small annular length in the radial direction. For example, the projection 131 may be formed such that the radial length of the annular contact surface between the projection 131 of the seal member 13 and the pressing member 6 is only about 0.2 mm. As described above, the sealing member 13 has an opening 125 between the plate-shaped sliding portion 122 and the end face on the one end side of the arm 8 , and a gap between the plate-shaped sliding portion 122 and the pressing member 6 . It closes the opening 126 and also covers the opening 104 on the one end side of the holding chamber 103 of the rolling bearing 10 .

As shown in FIG. 2 , on a part of the surface on the other end side of the seal member 13 , a convex portion 14 is formed in a portion that is in annular contact with the arm 8 . It is fitted with a recess 15 formed in the . The cross section of the protrusion 14 of the seal member 13 is circular. Also, the outer diameter of the convex portion 14 of the sealing member 13 is substantially the same as the outer diameter of the concave portion 15 of the arm 8 up to the depth corresponding to the depth of the convex portion 14 of the sealing member 13 in the concave portion 15 of the arm 8 . Somewhat small. Further, the concave portion 15 of the arm 8 has a shape that is hollowed out to a depth significantly deeper than the depth of the convex portion 14 of the seal member 13 in order to reduce the weight of the auto tensioner 2 . The cross section of the protrusion 14 may not be circular, and the recess 15 of the arm 8 may be hollowed out to a depth substantially equal to that of the protrusion 14 of the seal member 13 . Further, when a projection is formed on a portion of one end surface of the boss portion 83 of the arm 8, at least the surface of the other end side of the seal member 13 is formed so as to be able to be fitted to the projection of the arm 8. A recess may be formed in one portion.

As shown in FIG. 3 , a plurality of convex ribs 132 are formed along the radial direction of the axis of the shaft portion 4 on one end side surface of the seal member 13 . For example, the surface of the sealing member 13 on the one end side may be formed with eight convex ribs 132 that are substantially evenly divided on the circumference.

The seal member 13 is entirely made of an elastic material. For example, the seal member 13 may be entirely made of polyamide resin (nylon 6T). The elastic material forming the sealing member 13 may be a synthetic resin material. In this case, the coating material for the sliding surface of the sliding member 12 can be used as the resin material. Also, the elastic material forming the sealing member 13 may be a rubber composition. For example, rubber compositions containing rubber components such as chloroprene rubber, urethane rubber, nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, silicone rubber, and fluorine rubber can be used. These rubbers have excellent heat resistance. Moreover, various additives such as solid lubricants may be added to the rubber composition. It should be noted that the seal member 13 does not have to be entirely made of an elastic material. The seal member 13 may include a portion formed of an elastic material, and a portion of the portion formed of the elastic material may be in annular contact with both the one end surface of the arm 8 and the pressing member 6 .

As shown in FIGS. 2 and 3, the arrangement of the fastening bolt 5 eccentrically with respect to the axis R of the shaft portion 4 will be explained later in the explanation of the assembly of the auto tensioner 2 to the engine block and the attachment of the belt. , assembly of the auto-tensioner 2, and operation of the auto-tensioner 2 will be described.

(Assembly of Auto Tensioner 2 to Engine Block and Installation of Belt 3)
Due to unavoidable dimensional tolerances of the camshaft drive belt system 1 such as dimensional tolerances of each part of the auto tensioner 2 and tolerances of the distance between parts (for example, variations in belt length), the same posture with respect to the engine block may occur. Even after assembly, the initial tension applied to the belt varies depending on the device. Therefore, the auto tensioner 2 of the present embodiment is constructed so as to apply a predetermined belt initial tension to the belt when it is assembled to the engine block. A premise configuration will be described. As shown in FIGS. 2 and 3, the center 91 of the pulley 9, which is the center of rotation of the pulley 9, is arranged eccentrically with respect to the axis R of the shaft portion 4, and the fastening bolt 5 is positioned with respect to the axis R of the shaft portion 4. placed eccentrically. In the auto tensioner 2 of this embodiment, when a predetermined belt load acts on the rotating shaft of the pulley 9, a predetermined initial tension is applied to the belt, and the belt is normally mounted, the arm 8 and the circular arc center position of the notch of the anti-rotation portion 74 of the base 7 are configured to match (that is, match marks match). Note that the indicator portion 85 provided on the arm 8 of the auto tensioner 2 before the work of assembling it to the engine block is located on the left side of the drawing in FIG. 3 with respect to the upper side of the drawing. For example, it may be positioned at about 35° in the X direction from above the plane of the paper.

The procedure from assembling the auto tensioner 2 to the engine block to attaching the belt will be described. As shown in FIG. 3, the X direction is the direction in which the circumferential biasing force of the coil spring 11 acts. The Y direction is the direction against the circumferential biasing force of the coil spring 11 . (1) The fastening bolt 5 is passed through the bolt insertion hole 52 provided in the shaft portion 4 and temporarily fixed to the female screw portion of the engine block. (2) The locking portion 274 of the anti-rotation portion 74 of the base 7 is engaged with the concave groove formed in the surface of the engine block on one end side. (3) In the temporary fixing state, the side surface (substantially hexagonal shape) of the pressing member 6 is gripped with a tool such as a spanner, and the shaft portion 4 is rotated in the X direction around the bolt. As a result, the tensioner as a whole rotates in the X direction about the center 51 of the bolt, and the position of the shaft R (that is, the pulley 9 and the arm 8) moves in the direction toward the belt (to the right on the page). (4) When the pulley 9 contacts the belt, the belt load acts on the rotation shaft of the pulley 9 . (5) Further, when the shaft portion 4 is rotated in the X direction around the center 51 of the bolt, torque is generated around the axis R of the shaft portion 4 that is eccentric from the rotation axis of the pulley 9 due to the increase in the belt load. Then, the arm 8 begins to rotate in the Y direction against the circumferential biasing force of the coil spring 11, and the tension of the belt begins to increase. (6) By further rotating the shaft portion 4 in the X direction about the center 51 of the fastening bolt 5 until a predetermined belt load acts on the rotation shaft of the pulley 9, the arm 8 and the pulley 9 are further moved to the axis R. It rotates about the center in the Y direction and can apply a predetermined initial tension to the belt. Here, confirmation that a predetermined belt load acts on the rotating shaft of the pulley 9 and that a predetermined initial tension is applied to the belt is performed by the joint formed by the indicator portion 85 of the arm 8 and the detent portion 74 of the base 7. This is done by checking whether the marks match. (7) With the matching marks aligned, the bolt is completely tightened to the female screw portion of the engine block, and the fixed portion such as the shaft portion 4 is fixed to the engine block.

As shown in FIGS. 2 and 3, by making not only the pulley 9 but also the fastening bolt 5 eccentric with respect to the axis R, even if there are unavoidable dimensional tolerances in the belt system device in mass production, all these dimensions can be achieved. A belt system device can be obtained in which the influence of tolerance is canceled and a predetermined belt load is always uniformly applied to the rotating shaft of the pulley 9 to impart a predetermined initial tension to the belt. In addition, by providing the match mark function, the work related to the assembly of the auto tensioner 2 to the engine block and the attachment of the belt can be performed accurately, and the work load can be reduced.

In contrast to the above, when the bolt insertion hole 52 is positioned coaxially with the axis R, the above operation (3) cannot be performed. Therefore, even if the fixing portion such as the shaft portion is fixed to the engine block with the match marks aligned, the belt may not be attached to the belt by the device due to the dimensional tolerance of each part of the auto tensioner and the tolerance of the distance between parts. Variation occurs in the initial tension applied.

(Assembly of auto tensioner 2)
The auto tensioner 2 described above is assembled in the following steps. First, the shaft portion 4 , the base 7 , the coil spring 11 , the rolling bearing 10 and the pulley 9 are assembled to the arm 8 . Next, the seal member 13 is assembled to one end surface of the boss portion 83 of the arm 8 . Next, the sliding member 12 is assembled with the arm 8 . A member group including the arm 8 that is assembled to the arm 8 and integrated with the arm 8 is assembled to the shaft portion 4 so that the inner surface of the cylindrical sliding portion 121 of the sliding member 12 and the outer surface of the shaft portion 4 are in contact with each other. . Next, the pressing member 6 is press-fitted and fixed to the end portion on the one end side of the shaft portion 4 .

(Operation of auto tensioner 2)
In this embodiment, a damping portion is not provided separately from the sliding member 12 , and the coil spring 11 is compressed in the direction of the axis R of the shaft portion 4 . Therefore, the plate-like sliding portion 122 of the sliding member 12 functions as a damping portion, and the auto tensioner 2 has symmetrical damping characteristics. In this case, the magnitude of the frictional force generated in the plate-like sliding portion 122 is substantially the same whether the belt tension is increased or decreased.

When the tension of the belt increases, the arm 8 receives the load from the belt and rotates in the direction (Y direction) against the biasing force of the coil spring 11 in the circumferential direction. In this case, the plate-like sliding portion 122 of the sliding member 12 mainly functions as a damping portion to damp the rotation of the arm 8 .

When the tension of the belt decreases, the torsional restoring force of the coil spring 11 becomes dominant, and the arm 8 resists the damping force of the plate-like sliding portion 122 with respect to the rotation of the arm 8. It rotates in the direction (X direction) in which the circumferential biasing force acts. In this case, the arm 8 is caused to follow and the belt tension is increased (restored).

(Effect)
In this embodiment, the gap between the plate-like sliding portion 122 of the sliding member 12 and the arm 8 and the gap between the plate-like sliding portion 122 and the pressing member 6 are covered with the seal member 13, which is a relatively simple configuration. This makes it difficult for foreign matter such as dust to enter the gap, thereby improving the durability of the auto tensioner.

Also, the seal member 13 is provided on the arm 8 so as not to be relatively rotatable, and rotates integrally with the arm 8 . Therefore, unlike the case where the sealing member 13 is provided on the fixed side as in the above-mentioned Patent Document 2, there is no difficulty in installing the sealing member 13, and there is no need to add a dedicated member for supporting the sealing member 13. do not have.

In this embodiment, the seal member 13 is sandwiched between the plate-like sliding portion 122 and the end surface of the arm 8 on the one end side. As a result, the seal member 13, the arm 8, and the plate-like sliding portion 122 rotate together. In addition, since the seal member 13 is sandwiched between the plate-like sliding portion 122 and the end surface of the arm 8, the opening 125 between the plate-like sliding portion 122 and the end surface of the arm 8 is reliably closed. escape.

In the present embodiment, concave portions and convex portions are provided on the end surface of the arm 8 on one end side and the facing surface of the seal member 13 facing the end surface so as to fit together. Thereby, the seal member 13 can be configured to be non-rotatable with respect to the arm 8 .

In this embodiment, the seal member 13 covers the opening 104 on the one end side of the holding chamber 103 of the rolling bearing 10 . As a result, the sealing member 13 can also prevent foreign matter from entering the holding chamber 103 of the rolling bearing 10 .

In this embodiment, the sliding member 12 is formed with a slit 124 extending in the axial direction and has a C-shaped cross section. 8 larger than the inner diameter of the boss portion 83 . As a result, the sliding member 12 is attached to the boss portion 83 of the arm 8 in a slightly contracted state. Therefore, the cylindrical sliding portion 121 can be brought into pressure contact with the inner surface of the boss portion 83 of the arm 8 by the self-elastic restoring force of the sliding member 12 in the diameter-expanding direction, and the sliding member 12 moves against the arm 8. Relative rotation becomes impossible more reliably. Therefore, the inner surface of the cylindrical sliding portion 121 and the one end surface of the plate-shaped sliding portion 122 can more reliably function as sliding surfaces of the sliding member 12 .

In this embodiment, the base material of the sliding member 12 is made of metal. is made of a synthetic resin material having surface properties of As a result, abrasion of the sliding surface of the sliding member 12 can be suppressed, and the durability of the sliding member 12 can be ensured.

In this embodiment, the coil spring 11 is compressed in the axial direction of the shaft portion 4 . As a result, the coil spring 11 presses the arm 8 by the elastic restoring force of the shaft portion 4 in the axial direction. Since the plate-like sliding portion 122 of the sliding member 12 is present between the boss portion 83 of the arm 8 and the pressing member 6 , the plate-like sliding portion 122 has the axial line of the shaft portion 4 of the coil spring 11 . A directional elastic restoring force is applied. Therefore, a frictional force is generated between the plate-like sliding portion 122 and the pressing member 6 , and the plate-like sliding portion 122 functions as a damping member that dampens the swinging motion of the arm 8 .

Since the plate-shaped sliding portion 122 is strongly pressed against the pressing member 6, the degree of uneven wear of the plate-shaped sliding portion 122 also increases. Therefore, the provision of the seal member 13 is significant in order to prevent foreign matter from entering the vicinity of the plate-like sliding portion 122 . Further, when a configuration in which a portion of the seal member 13 is arranged between the plate-shaped sliding portion 122 and the end surface of the arm 8 is adopted, the seal member 13 is strongly held by the restoring force of the coil spring 11. Therefore, the effect of integrating the arm 8, the plate-shaped sliding portion 122, and the seal member 13 is enhanced.

In this embodiment, the sealing member 13 includes a portion made of elastic material. This makes it easier for the sealing member 13 to come into close contact with the periphery of the plate-like sliding portion 122, thereby enhancing the sealing effect.

In this embodiment, a portion of the sealing member 13 formed of an elastic member is in annular contact with both the end face of the arm 8 on the one end side and the pressing member 6 . As a result, a portion of the sealing member 13 made of an elastic material contacts both the end face of the arm 8 on the one end side and the pressing member 6 , thereby opening the gap between the plate-shaped sliding portion 122 and the pressing member 6 . The opening 125 between the portion 126 and the plate-like sliding portion 122 and the end surface of the boss portion 83 of the arm 8 on the one end side can be reliably closed.

Also, if a portion of the seal member 13 is in contact with both the end face of the arm 8 and the pressing member 6, the pressing member 6 is in contact only with the plate-like sliding portion 122. The contact surface pressure between the portion 122 and the pressing member 6 is relaxed. As a result, it is possible to suppress the generation of abnormal noise when the plate-shaped sliding portion 122 and the pressing member 6 come into frictional contact with each other.

In this embodiment, the sealing member 13 has a protrusion 131 that makes line contact with the pressing member 6 . As a result, the contact area between the sealing member 13 and the pressing member 6 is reduced, and the contact resistance between the sealing member 13 and the pressing member 6 is reduced, so that the sealing member 13 can rotate integrally with the arm 8 more reliably. .

In this embodiment, the seal member 13 is entirely made of an elastic material. As a result, the manufacturing cost can be reduced as compared with the case where the seal member 13 includes a portion not made of an elastic material.

In this embodiment, a plurality of convex ribs 132 are formed along the radial direction of the axis of the shaft portion 4 on the surface of the sealing member 13 on one end side. As a result, the rigidity of the seal member 13 in the radial direction of the shaft center of the shaft portion 4 is increased, so that the seal member 13 is fitted and supported more reliably in contact with the arm 8 so as not to be able to rotate relative to the arm 8 , and is integrated with the arm 8 . can rotate freely.

In this embodiment, the arm 8 is eccentrically supported by the base 7 and the pulley 9 is attached to the outer peripheral side of the arm 8 . This is suitable for a camshaft drive belt system 1 in which it is better not to rotate the arm 8 too much.

(Other embodiments)
Although the preferred embodiments of the present invention have been described above, the above embodiments can be implemented with the following modifications.

A flange is formed integrally with the shaft at one end of the shaft, and this flange may function as the pressing member of the present invention. In this case, preferably, not only the other end surface of the shaft portion but also the other end surface of the base are brought into contact with the surface on the one end side of the engine block via the fastening bolt.

The opening 126 of the gap between the pressing member 6 and the plate-shaped sliding portion 122 may not be completely closed.

The sliding member may be entirely made of a synthetic resin material, including the sliding surface, or entirely made of metal, including the sliding surface.

The material of the inner surface, which is the sliding surface of the cylindrical sliding portion, may be the same or different depending on whether the cylindrical sliding portion of the sliding member functions as a sliding bearing or as a damping portion. However, when the cylindrical sliding portion functions as a sliding bearing, the inner surface of the cylindrical sliding portion is formed of a material having surface properties with a lower coefficient of friction than when functioning as a damping portion. preferably.

The sealing member may have an annular core. For example, a cold-rolled steel plate, an electrogalvanized steel plate, a stainless steel plate, an aluminum alloy plate, or the like may be used as the core.

The entire sealing member may be made of metal, or may be a composite system of elastic material/metal. In this case, from the viewpoint of preventing abnormal noise (rubbing noise) from occurring, the surface of the other end of the pressing member is preferably formed of a synthetic resin material having a surface characteristic of a lower coefficient of friction than that of a metal material.

The seal member 13 may be in contact with the inner surface of the pulley 9 as shown in FIG. As a result, foreign matter can be more reliably prevented from entering through the opening 104 on the one end side of the holding chamber 103 of the rolling bearing 10 .

Further, the application is not limited to timing belts used in camshaft drive belt systems, and may be applied to auto tensioners that keep constant the slack side tension of transmission belts that drive accessories of automobile engines.

1 Camshaft drive belt system 2 Auto tensioner 3 Belt 4 Shaft 5 Fastening bolt 6 Pressing member 7 Base 8 Arm 9 Pulley 10 Rolling bearing 11 Coil spring 12 Sliding member 13 Sealing member

Claims (10)

a base fixed to the engine block and to which the shaft is attached;
an arm rotatably supported by the base via the shaft;
a pulley mounted rotatably around an axis parallel to the shaft and capable of coming into contact with the belt;
a rolling bearing interposed between the arm and the pulley and having a holding chamber for accommodating rolling elements between the inner ring and the outer ring;
a cylindrical sliding portion arranged between the boss portion of the arm and the shaft portion; a sliding member having a plate-like sliding portion disposed between an end surface and a pressing member connected to the shaft portion, the sliding member rotating integrally with the arm;
a coil spring disposed around the shaft portion and biasing the arm to rotate in one direction with respect to the base;
a sealing member provided on the arm so as not to rotate relative to the plate-shaped sliding portion, and a seal member arranged to cover a gap between the end surface of the arm on the one end side and the pressing member; e,
The seal member includes a portion made of an elastic material, and the portion made of the elastic material is in annular contact with both the end surface of the arm on the one end side and the pressing member,
The auto tensioner , wherein the seal member has a protrusion that makes line contact with the pressing member . 2. The auto tensioner according to claim 1, wherein the seal member is sandwiched between the plate-like sliding portion and the end surface of the arm on the one end side. 3. The end surface of the arm on the one end side and the facing surface of the sealing member facing the end surface are provided with concave portions and convex portions so as to be fitted to each other, according to claim 2. auto tensioner. 4. The auto tensioner according to any one of claims 1 to 3, wherein the seal member covers an opening on the one end side of the holding chamber of the rolling bearing. The sliding member has a C-shaped cross section formed with a slit extending in the axial direction, and in a no-load state, the outer diameter of the cylindrical sliding portion is equal to the inner diameter of the boss portion of the arm. 5. An autotensioner according to any one of the preceding claims, characterized in that it is greater than . The base material of the sliding member is made of metal, and the inner surface of the cylindrical sliding portion and the end surface of the plate-like sliding portion on the one end side have surface characteristics with a lower coefficient of friction than the base material. 6. The auto tensioner according to claim 1, wherein the auto tensioner is made of a synthetic resin material having 7. The auto tensioner according to claim 1, wherein said coil spring is compressed in the axial direction of said shaft portion. 8. The auto tensioner according to any one of claims 1 to 7 , wherein said sealing member is entirely made of an elastic material. a base fixed to the engine block and to which the shaft is attached;
an arm rotatably supported by the base via the shaft;
a pulley mounted rotatably around an axis parallel to the shaft and capable of coming into contact with the belt;
a rolling bearing interposed between the arm and the pulley and having a holding chamber for accommodating rolling elements between the inner ring and the outer ring;
a cylindrical sliding portion arranged between the boss portion of the arm and the shaft portion; a sliding member having a plate-like sliding portion disposed between an end surface and a pressing member connected to the shaft portion, the sliding member rotating integrally with the arm;
a coil spring disposed around the shaft portion and biasing the arm to rotate in one direction with respect to the base;
a sealing member provided on the arm so as not to rotate relative to the plate-shaped sliding portion, and a seal member arranged to cover a gap between the end surface of the arm on the one end side and the pressing member; e,
An auto tensioner , wherein a plurality of convex ribs are formed along the radial direction of the axis of the shaft portion on the surface of the sealing member on the one end side . 10. The auto tensioner according to claim 1 , wherein said arm is eccentrically supported by said base, and said pulley is attached to the outer peripheral side of said arm.

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