JP2007002941A - Hydraulic auto-tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic auto-tensioner capable of taking an assembly posture in which an uneven load is not applied even if surface accuracy of an attachment surface is bad. <P>SOLUTION: A spherical projection part 26 is provided on an upper end of a rod 13 which can extend and contract relatively to a cylinder 22. A liner 27 is fitted on the spherical projection part 26, and the liner 27 is pressed in a roughly semi-spherical recess part 29 of a bearing member 28. A skirt part 27b provided on a lower end of the liner 27 is deformed inward to enclose the spherical projection part 26 after press in, and the bearing member 28 is prevented from separating from the spherical projection part 26. The bearing member 28 is attached to an engine block 40, inclination of the bearing member 28 is absorbed by slip motion of a spherical contact part of the liner 27 and the spherical projection part 26 when the bearing member 28 is inclined at a time of assembly, and the hydraulic auto-tensioner is prevented from having uneven load applied thereon. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic auto tensioner used for tension adjustment of an accessory driving belt for driving an engine accessory such as an alternator.

  In general, in a belt transmission that drives an engine accessory, an adjustment force of an auto tensioner is applied to a swingable pulley arm that rotatably supports a tension pulley for adjusting the tension of the belt, and the tension pulley is pressed against the belt. The belt tension change is absorbed by the auto tensioner to keep the belt tension constant.

  As the auto tensioner, the one described in Patent Document 1 has been conventionally known. The auto tensioner includes a cylinder filled with hydraulic oil, a seal member that seals the upper opening of the cylinder, a rod that slidably passes through the seal member, and a rod and a cylinder in a direction in which the rod and the cylinder extend. And a return spring that urges the rod and the contracting direction pushing force applied to the rod and the cylinder is buffered by a hydraulic damper incorporated in the cylinder.

In the above hydraulic auto tensioner, connecting pieces are provided at the closed end of the cylinder and the tip of the rod, a bush is inserted into a bush insertion hole formed in each connecting piece, and a bolt inserted into the bush is tightened. The bush is fixed to a pulley arm or an engine block, one connecting piece is swingably connected to the pulley arm, and the other connecting piece is swingably connected to the engine block.
Japanese Patent Laid-Open No. 10-299846

  By the way, when the bush is fixed by tightening a bolt and the rod side connecting piece and the cylinder side connecting piece are supported swingably around the bush as in the hydraulic auto tensioner, the engine block When the surface accuracy of the bush fixing surface and the bush end surface is poor, the bush is inclined. At this time, since the tilt also occurs in the hydraulic auto tensioner, an uneven load acts on the hydraulic auto tensioner when adjusting the belt tension, and the tension change of the belt cannot be absorbed smoothly. This will reduce the durability of the auto tensioner.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic auto tensioner that can be easily mounted so as to obtain a mounting state in which an eccentric load is not applied even when the surface accuracy of the mounting surface is poor.

  In order to solve the above problems, in the present invention, a cylinder filled with hydraulic oil, a seal member that seals the upper opening of the cylinder, a rod that slidably penetrates the seal member, and the rod A hydraulic auto-tensioner having a return spring that urges the cylinder in the extending direction so that the pushing force in the contracting direction applied to the rod and the cylinder is buffered by a hydraulic damper provided inside the cylinder. In this embodiment, a spherical protrusion is provided at the tip portion located outside the cylinder of the rod, and the bearing member attached to the engine block has a substantially hemispherical recess having a size capable of accommodating more than half of the spherical protrusion. The skirt portion provided at the opening end is deformed inward by press-fitting into the concave portion between the concave portion and the spherical protrusion, so that the spherical protrusion Together wrap the is the adopted configuration incorporating a substantially hemispherical liner of the spherical projection and the spherical contact.

  Here, by providing a plurality of notches in the skirt portion at intervals in the circumferential direction, the skirt portion can be easily deformed inward when the liner is press-fitted into the concave portion of the bearing member. The bearing members can be easily connected to each other with a small pressure input.

  In the hydraulic auto tensioner according to the present invention, a connecting piece is provided at the lower end of the cylinder, the liner is held by a bifurcated portion provided at the lower part of the connecting piece, and the spherical head of the bolt is held by the liner, When the spherical head and the liner are brought into spherical contact, the bolt can be screwed into the pulley arm so that it can be connected to the hydraulic auto tensioner and the pulley arm, so that the connection is easy.

  Further, if the bolt screwed into the pulley arm is inclined, a displacement movement occurs between the spherical head and the spherical contact portion of the liner, and the inclination of the bolt can be absorbed by the displacement movement. For this reason, it is possible to prevent an uneven load from being applied to the hydraulic auto tensioner from the pulley arm.

  In the case where the pulley arm connecting bolt is held by the connecting piece, the inner surface of the bifurcated portion is formed of a hemispherical surface and a cylindrical surface continuous to the end of the hemispherical surface, and the inner surface of the liner is formed into a spherical shape of a spherical head. A hemispherical surface that conforms to the surface and a cylindrical surface that continues to the end of the hemispherical surface, and an outer surface that conforms to the hemispherical surface of the bifurcated portion, and a conical surface that continues to the end of the hemispherical surface By forming the liner into the spherical head and press-fitting into the bifurcated part, both ends of the liner are deformed inward to wrap the spherical head, so bolts can be easily attached it can.

  As described above, by providing a skirt portion at the opening end of the liner, when the liner is fitted to the spherical protrusion of the rod and press-fitted into the recess of the bearing member, the skirt portion is brought into contact with the inner periphery of the opening of the recess. Since it deforms inward and encloses the spherical protrusion, the rod and the bearing member can be connected easily and securely, and the bearing member is separated at the stage prior to assembly of the hydraulic auto tensioner. There is no occurrence.

  Further, by bolting the bearing member to the engine block, the tip of the rod can be connected to the engine block, and the hydraulic auto tensioner can be easily assembled.

  Furthermore, since the spherical protrusion of the rod and the liner are in spherical contact with each other in the coupled state of the rod and the bearing block, the surface accuracy of the bearing mounting surface of the engine block is poor, and if the bearing member is tilted, the spherical surface A displacement movement occurs at the contact portion, and the inclination of the bearing member is absorbed.

  For this reason, it is possible to obtain a good mounting posture in which an uneven load is not applied to the assembly of the hydraulic auto tensioner, and it is possible to suppress a decrease in durability. Further, the belt swing can be effectively absorbed.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a belt tension adjusting device. As shown in the figure, the pulley arm 1 is supported so as to be swingable about a fulcrum shaft 2, and a tension pulley 3 is rotatably supported at one end thereof. A hydraulic auto tensioner 10 is connected to the other end of the pulley arm 1, and the pulley arm 1 is biased by the hydraulic auto tensioner 10 in a direction in which the tension pulley 3 presses the belt 4.

  As shown in FIG. 2, the hydraulic auto tensioner 10 includes a bottomed cylinder 11 made of an aluminum alloy filled with hydraulic oil, and an upper opening of the cylinder 11 that seals air on the hydraulic oil surface. A seal member 12 that forms a rod, a rod 13 that slidably passes through the seal member 12, a return spring 14 provided outside the cylinder 11, and a cylinder 11 and a rod provided inside the cylinder 11. And a hydraulic damper 15 for buffering the pushing force in the direction of contracting 13.

  The return spring 14 is assembled between a spring seat 16 provided at the upper part of the rod 13 located outside the cylinder 11 and a flange 17 provided at the lower outer periphery of the cylinder 11 so that the cylinder 11 and the rod 13 extend in the direction of extension. 11 and the rod 13 are energized.

  The hydraulic damper 15 slidably incorporates a plunger 19 into a steel bottomed sleeve 18 fitted inside the cylinder 11 to partition the inside of the cylinder 11 into a pressure chamber 20 and a reservoir chamber 21. 19 is provided with a passage 22 communicating with the pressure chamber 20 and the reservoir chamber 21, and a check valve 23 is provided in the passage 22, and a plunger spring 24 is incorporated into the pressure chamber 20 to press the plunger 19 against the lower end of the rod 13. ing.

  Here, the check valve 23 closes the passage 22 when the pressure in the pressure chamber 20 becomes higher than the pressure in the reservoir chamber 21.

  A wear ring 25 is fitted to an intermediate portion of the rod 13 located in the cylinder 11. The wear ring 25 moves together with the rod 13 when the cylinder 11 and the rod 13 are relatively expanded and contracted, and is guided by the inner diameter surface of the cylinder 11 during the movement.

  A spherical protrusion 26 is provided at the upper end of the rod 13, and a liner 27 fitted to the spherical protrusion 26 is fitted in a recess 29 formed on the lower surface of the bearing member 28.

  The bearing member 28 is fixed to the engine block 40 by tightening bolts 30. The concave portion 29 formed on the lower surface of the bearing member 28 has a substantially hemispherical shape, and the inner surface thereof includes a hemispherical inner surface 29a and a cylindrical inner surface 29b continuous with the lower end thereof as shown in FIG. Is formed.

  The liner 27 has a hemispherical portion 27a fitted to the spherical protrusion 26 of the rod 13, and a skirt portion 27b continuous to the lower end of the hemispherical portion 27a, and a plurality of notches 27c are circumferentially formed in the skirt portion 27b. Are formed at intervals.

Here, the hemispherical inner surface f ₁ of the hemispherical portion 27 a conforms to the spherical surface of the spherical protrusion 26, and the hemispherical outer surface f ₂ conforms to the hemispherical inner surface 29 a of the recess 29.

The inner surface f _{3 of the} skirt portion 27 b has a cylindrical shape, and the inner diameter of the cylindrical inner surface f _{3 is} the same as the inner diameter of the hemispherical portion 27 a. Further, the outer surface f ₄ of the skirt portion 27 b expands toward the lower end, and the outer diameter of the lower end of the outer surface f ₄ is larger than the inner diameter of the cylindrical inner surface 29 b of the recess 29.

As shown in FIG. 3 (II), the liner 27 is fitted into the spherical protrusion 26 of the rod 13 and is press-fitted into the recess 29 of the bearing member 28 in the fitted state. At the time of the press-fitting, as shown in FIGS. 3 (III) and 4 (I), the outer surface f ₄ of the skirt portion 27b abuts on the opening edge of the cylindrical inner surface 29b of the recess 29, Is further pushed into the skirt portion 27b by contact with the cylindrical inner surface 29b, and the spherical protrusion 26 is encased as shown in FIGS. 3 (IV) and 4 (II). Become.

Here, since the skirt portion 27b is formed with a plurality of cuts 27c, the skirt portion 27b is easily deformed inward, and the spherical protrusion 26 is wrapped by the skirt portion 27b by the deformation. The portion 26 is prevented from coming off. Further, the outer surface f ₄ of the skirt portion 27 b is in strong pressure contact with the cylindrical inner surface 29 b, and the liner 27 is prevented from coming off by the pressure contact, and the spherical protrusion 26 and the bearing member 28 are connected to each other through the liner 27. It is held and is not separated at the stage before the assembly of the hydraulic auto tensioner 10.

  As shown in FIG. 2, a connecting piece 31 is provided on the lower surface of the cylinder 11. The connecting piece 31 has a bifurcated portion 32 at the lower end, and a liner 33 is held by the bifurcated portion 32. A spherical head 34 a of a bolt 34 screwed into the pulley arm 1 is held by the liner 33.

As shown in FIG. 5 (I), (II) , the inner surface of the bifurcated portion 32 includes a semi-spherical f _5, is formed by a cylindrical surface f ₆ that is continuous with the edge of the hemisphere f _5, engaged to the inner surface A joint groove 35 is provided.

The liner 33 has a U-shaped side surface, and its inner surface is formed by a hemispherical surface f ₇ that fits the spherical surface of the spherical head 34 a of the bolt 34 and a cylindrical surface f ₈ that is continuous with the end of the hemispherical surface f _7. ing. The outer surface of the liner 33 includes a hemispherical surface f ₉ that fits the hemispherical surface f ₅ of the bifurcated portion 32 and a conical surface f ₁₀ that continues to the end of the hemispherical surface f ₉ and expands toward the lower end. Is formed.
The outer surface of the liner 33 is provided with a protrusion 36 that can be engaged with an engagement groove 35 formed on the inner surface of the bifurcated portion 32, and the liner 33 is prevented from rotating by the engagement of the protrusion 36 and the engagement groove 35. Is done.

The liner 33 is fitted into the spherical head 34a of the bolt 34, and is press-fitted into the forked portion 32 from below the forked portion 32 in the fitted state. At the time of the press-fitting, the conical surface f ₁₀ comes into contact with the opening edge of the cylindrical surface f ₆ of the bifurcated portion 32 as shown in FIG. When thereof from the contact state further pressed into the forked portion 32, the lower end of the liner 33 by contact with the cylindrical surface f ₆ of the bifurcated portion 32 is deformed inwardly, the spherical head as shown in FIG. 5 (IV) The spherical head portion 34a is held by the liner 33 and is prevented from coming off. On the other hand, the conical surface f ₁₀ of the liner 33 is in strong pressure contact with the cylindrical surface f ₆ of the bifurcated portion 32, and the liner 33 is held by the bifurcated portion 32 by the pressure contact.

  For this reason, the spherical head 34 a of the bolt 34 is held by the bifurcated portion 32 via the liner 33, and is not separated from the bifurcated portion 32 at the stage of transportation before assembly of the hydraulic auto tensioner 10.

  The hydraulic auto tensioner 10 configured as described above is shown in FIG. 1 by bolting the bearing member 28 to the engine block 40 and screwing the bolt 34 held by the connecting piece 31 of the cylinder 11 into the pulley arm 1. The assembled state is as follows.

  In the assembled state as described above, when the belt 4 vibrates due to the fluctuation of the load and the belt 4 becomes slack, the cylinder 11 moves downward by the elastic force of the return spring 14 and the pulley arm 1 moves to the cylinder 11. The tension pulley 3 is pressed against the belt 4 and the slack of the belt 4 is absorbed.

  When the cylinder 11 moves downward, the pressure in the pressure chamber 20 decreases, so the check valve 23 opens the passage 22 and the hydraulic oil in the reservoir chamber 21 flows into the pressure chamber 20. For this reason, the cylinder 11 moves smoothly downward and immediately absorbs the slack of the belt 4.

  On the other hand, when the tension of the belt 4 increases, a pushing force is applied to the cylinder 11 via the tension pulley 3 and the pulley arm 1. At this time, since the pressure in the pressure chamber 20 becomes higher than the pressure in the reservoir chamber 21, the check valve 23 closes the passage 22 and the push-up force is buffered by the hydraulic oil in the pressure chamber 20.

  When the push-up force is larger than the spring force of the return spring 14, the hydraulic oil in the pressure chamber 20 flows into the reservoir chamber 21 through a minute leak gap formed between the sliding surface of the sleeve 18 and the plunger 19. The cylinder 11 slowly rises to a position where the pushing force and the spring force of the return spring 14 are balanced, and the tension of the belt 4 is kept constant.

  In the hydraulic auto tensioner 10 according to the embodiment, the liner 27 held in the recess 29 of the bearing member 28 and the spherical protrusion 26 provided at the upper end of the rod 13 are in spherical contact with each other. When the bearing member 28 is mounted on the bearing mounting surface when the bearing member 28 is inclined, if the bearing member 28 is tilted, the contact portion between the liner 27 and the spherical protrusion 26 is displaced, causing the bearing member 28 to move. It will absorb the inclination of.

  For this reason, when assembling the hydraulic auto tensioner 10, the hydraulic auto tensioner 10 is not affected by the surface accuracy of the engine block 40, and obtains a good assembling posture that is not loaded with an uneven load. be able to.

  In addition, the rod 13 and the bearing member 28 can be coupled by fitting the liner 27 to the spherical protrusion 26 of the rod 13 and press-fitting the liner 27 into the recess 29 of the bearing member 28. Thus, the bearing member 28 can be easily connected. In addition, at the time of press-fitting, the skirt portion 27b of the liner 27 is deformed inwardly and encloses the spherical protrusion 26, and the skirt portion 27b is strongly pressed against the cylindrical inner surface 29b of the concave portion 29. Thus, the bearing member 28 and the liner 27 can be prevented from being separated at a stage before the hydraulic auto tensioner 10 is assembled.

  As shown in FIG. 2, the liner 33 is held by the bifurcated portion 32 of the connecting piece 31 provided at the lower end of the cylinder 11, the spherical head 34a of the bolt 34 is held by the liner 33, and the spherical head 34a If the bolt 34 screwed into the pulley arm 1 is inclined by making the contact with the liner 33 spherical, a displacement movement occurs at the contact portion between the spherical head 34a and the liner 33, and the displacement movement causes the bolt 34 to move. The inclination can be absorbed.

  For this reason, it is possible to prevent an unbalanced load from being applied to the hydraulic auto tensioner 10 from the bolt 34, smoothly absorb the change in tension of the belt 4, and improve the durability of the hydraulic auto tensioner 10. The decrease can be suppressed.

Further, by fitting the liner 33 to the spherical head 34a of the bolt 34 and press-fitting the liner 33 into the bifurcated portion 32 of the connecting piece 31, both end portions of the liner 33 are deformed inward and the spherical head 34a. Since the conical surface f ₁₀ of the liner 33 is strongly pressed against the cylindrical surface f ₆ of the bifurcated portion 32, the bolt 34 can be securely held, and the transportation stage before assembly of the hydraulic auto tensioner 10 can be performed. Therefore, there is no inconvenience that the bolt 34 and the liner 33 are separated.

  Further, by holding the bolt 34 by the bifurcated portion 32, the connecting piece 31 and the pulley arm 1 can be easily connected.

Front view of a belt tension adjusting device using a hydraulic auto tensioner according to the present invention. 1 is a longitudinal front view of the hydraulic auto tensioner shown in FIG. (I) to (IV) are cross-sectional views showing the coupling state of the rod and the bearing member in stages. (I) is an enlarged cross-sectional view showing a state immediately before the rod and the bearing member are coupled, and (II) is an enlarged cross-sectional view of the coupled state. (I) is a diagram showing a state before the coupling piece and the bolt are coupled, (II) is a sectional view taken along the line II in (I), (III) is a sectional view showing a state immediately before coupling, (IV) ) Is a sectional view of the coupled state

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic type auto tensioner 11 Cylinder 12 Seal member 13 Rod 14 Return spring 15 Hydraulic damper 26 Spherical protrusion 27 Liner 27b Skirt part 27c Notch 28 Bearing member 29 Recess 31 Connection piece 32 Forked part 33 Liner 34 Bolt 34b Spherical head 40 Engine Block f ₅ hemispherical surface f ₆ cylindrical surface f ₇ hemispherical surface f ₈ cylindrical surface f ₉ hemispherical surface f ₁₀ conical surface

Claims (4)

  A cylinder filled with hydraulic oil, a seal member that seals the upper opening of the cylinder, a rod that slidably passes through the seal member, and a return spring that biases the rod and the cylinder in the extending direction. In the hydraulic auto tensioner in which the pushing force applied in the contraction direction applied to the rod and the cylinder is buffered by a hydraulic damper provided in the cylinder, the tip of the rod located outside the cylinder The bearing member provided with the spherical protrusion and attached to the engine block is formed with a substantially hemispherical recess having a size capable of accommodating more than half of the spherical protrusion, and a recess is formed between the recess and the spherical protrusion. The skirt provided at the opening end due to the press-fitting to the inner surface deforms inward to wrap around the spherical protrusion, and substantially contacts the spherical protrusion. Hydraulic auto-tensioner, characterized in that incorporating spherical liner.   The hydraulic auto tensioner according to claim 1, wherein a plurality of cuts are formed in the skirt portion at intervals in the circumferential direction.   A connecting piece is provided at the lower end of the cylinder, the liner is held by a bifurcated portion provided at the lower part of the connecting piece, the spherical head of the bolt is held by the liner, and the spherical head and the liner are brought into spherical contact with each other. The hydraulic auto tensioner according to claim 1 or 2.   The inner surface of the bifurcated portion is formed by a hemispherical surface and a cylindrical surface continuous to the end of the hemispherical surface, and the inner surface of the liner is adapted to the spherical surface of the spherical head, and the hemispherical surface ends. The outer surface is formed of a hemispherical surface adapted to the hemispherical surface of the bifurcated portion and a conical surface continuous to the end of the hemispherical surface, and a liner is formed from below the bifurcated portion to the inside. 4. The hydraulic auto tensioner according to claim 3, wherein the spherical head is wrapped by press-fitting and deforming both ends of the liner inward by contact of the conical surface with the cylindrical surface of the bifurcated portion.

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