JP2007002983A - Hydraulic auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate manufacturing of a rod of a hydraulic auto tensioner comprising: a spherical part capable of preventing an uneven load from being applied from an engine block side; and a spring seat on which spring force of a return spring is applied. <P>SOLUTION: The hydraulic auto tensioner is provided with the spherical part 16 supported by a spherical inner surface in an engine block 40 side on a tip of a rod 13 inserted in a cylinder 11, and is provided with the spring seat 17 provided at a lower part of the spherical part 16 and receiving spring force of the return spring 14. The spring seat 17 is a separate body from the rod 13. A split collet 19 is assembled between a taper inner surface of a taper hole 18 formed on a center of the spring seat 17 and an outer diameter surface of a rod 13, and the rod 13 is fixed on the spring seat 17 by the collet 19. Consequently, manufacturing of the rod with the spring seat is facilitated. <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.

  In order to prevent such inconvenience, a spherical portion is provided at the tip of the rod, while a bearing member is attached to the engine block, and the spherical portion is formed on the spherical inner surface of the hemispherical recess provided in the bearing member. If supported, the reaction force of the axial load applied to the bearing member from the pulley arm via the hydraulic auto tensioner can be loaded on the shaft center of the rod. Although it is extremely effective as a load prevention measure, when the spring seat and the spherical portion are integrated with the rod, the shape becomes complicated, so that the processing becomes difficult and the processing cost increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a spring-wrapped hydraulic auto tensioner for preventing an unbalanced load so that a rod having a spherical portion and a spring seat can be easily formed.

  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, A contraction loaded on the rod and the cylinder, which is incorporated outside and has a return spring supported at one end by a spring seat provided on the rod and supported at the other end by a flange provided at the lower outer periphery of the cylinder. In a spring-clad hydraulic auto tensioner in which the pushing force in the direction is buffered by a hydraulic damper provided inside the cylinder, the rod and the spring seat are separated from each other, and the tip of the rod is on the engine block side. A spherical portion that is contact-guided by a spherical inner surface is provided, the spring seat is provided below the spherical portion, and a lower end small diameter tape formed at the center of the spring seat. Embedded collet which is split in the circumferential direction between the outer diameter surface of the tapered inner surface and the rod of the path hole, it was adopted a structure in which a matching tapered surface to the tapered inner surface of the tapered hole to the outer periphery of the collet.

  Here, by providing a positioning means for positioning the collet in the axial direction between the collet and the rod, the axial movement of the spring seat can be surely prevented, and the pressing force of the return spring is reduced to the rod. Can be reliably loaded.

  As the positioning means, an engagement groove extending in the circumferential direction on the outer periphery of the rod, and a protrusion formed on the inner periphery of the collet can be employed to engage with the engagement groove.

  As described above, a spherical portion is formed at the tip of the rod, so that a spherical surface is formed on the bearing member attached to the engine block, and the spherical portion is supported by the spherical surface. Can be prevented, the hydraulic auto tensioner can be operated with high accuracy, and a decrease in durability can be suppressed.

  In addition, a spring seat is fitted to the rod, and a split collet whose outer periphery is a tapered surface is incorporated between the tapered hole formed in the spring seat and the outer diameter surface of the rod, so that the spring seat is loaded. The split collet is pressed radially inward by the pressing force of the return spring and comes into strong contact with the outer diameter surface of the rod. The spring seat can be firmly attached to the rod. The rod having it can be formed easily.

  Furthermore, since the rod having a spherical portion at the tip and the spring seat are separate, the rod and the spring seat can be easily processed, and a rod with a spring seat can be obtained at a low cost.

  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. 13 and a hydraulic damper 15 that cushions the pushing force in the contraction direction applied to 13.

  A spherical portion 16 is provided at the tip of the rod 13 located outside the cylinder 11, and a spring seat 17 is provided below the spherical portion 16.

  As shown in FIGS. 2 and 3, the spring seat 17 has a tapered hole 18 whose lower end has a small diameter at the center, and a collet 19 is incorporated between the tapered inner surface of the tapered hole 18 and the outer diameter surface of the rod 13. Yes.

  The collet 19 has a tapered surface 20 on the outer periphery that matches the tapered inner surface of the tapered hole 18. The collet 19 is divided in two in the circumferential direction.

  Positioning means 21 for positioning the collet 19 in the axial direction is provided between the collet 19 and the rod 13. The positioning means 21 forms an engagement groove 22 extending in the circumferential direction on the outer periphery of the rod 13, and a protrusion 23 is provided on the inner periphery of the collet 19. The protrusion 23 is engaged with the engagement groove 22 to collet. 19 is positioned.

  When mounting the spring seat 17, the split collet 19 is placed along the outside of the rod 13 so that the protrusion 23 on the inner surface engages with the engaging groove 22 of the rod 13, and then the lower end of the rod 13 is preliminarily placed. The fitted spring seat 17 is pulled up to a position where the collet 19 is accommodated in the tapered hole 18. FIG. 4 shows the attached state of the spring seat 17.

  The return spring 14 is assembled between a spring seat 17 provided at the tip of the rod 13 and a flange 24 provided at the lower outer periphery of the cylinder 11 so that the cylinder 11 and the rod 13 extend in a direction in which the cylinder 11 and the rod 13 extend. Energized.

  The hydraulic damper 15 slidably incorporates a plunger 26 into a steel bottomed sleeve 25 fitted inside the cylinder 11 to partition the inside of the cylinder 11 into a pressure chamber 27 and a reservoir chamber 28. 26 is provided with a passage 29 communicating with the pressure chamber 27 and the reservoir chamber 28, and a check valve 30 is provided in the passage 29, and a plunger spring 31 is incorporated in the pressure chamber 27 to press the plunger 26 against the lower end of the rod 13. ing.

  Here, the check valve 30 is configured to close the passage 29 when the pressure in the pressure chamber 27 becomes higher than the pressure in the reservoir chamber 28.

  A wear ring 32 is fitted in an intermediate portion of the rod 13 located in the cylinder 11. The wear ring 32 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 connecting piece 33 is provided at the lower end of the cylinder 11, and a bush 35 is inserted into a bush insertion hole 34 formed in the connecting piece 33.

  In the spring-clad hydraulic auto tensioner 10 having the above-described configuration, the bush 35 is fixed to the pulley arm 1 by tightening a bolt 36 inserted therein.

  On the other hand, the spherical portion 16 provided at the tip of the rod 13 is swingably supported by a bearing member 41 bolted to the engine block 40.

  Here, a substantially hemispherical concave portion 42 is formed on the lower surface of the bearing member 41, and a liner 43 that wraps the spherical portion 16 is incorporated in the concave portion 42, and a spherical inner surface 44 formed on the liner 43 is a spherical portion 16. In spherical contact with the spherical surface. The liner 43 may be omitted, and the spherical portion 16 of the rod 13 may be brought into direct contact with the spherical inner surface of the recess 42.

  In the assembled state of the hydraulic auto tensioner 10 as shown in FIGS. 1 and 2, when the belt 4 vibrates due to load fluctuations and the belt 4 is slackened, the cylinder 11 is lowered by the elastic force of the return spring 14. While moving in the direction, the pulley arm 1 is pushed by the cylinder 11 and swings, and the tension pulley 3 is pushed against the belt 4 to absorb the slack of the belt 4.

  When the cylinder 11 moves downward, the pressure in the pressure chamber 27 decreases, so the check valve 30 opens the passage 29 and the hydraulic oil in the reservoir chamber 28 flows into the pressure chamber 27. 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 27 becomes higher than the pressure in the reservoir chamber 28, the check valve 30 closes the passage 29 and the push-up force is buffered by the hydraulic oil in the pressure chamber 27.

  When the push-up force is larger than the spring force of the return spring 14, the hydraulic oil in the pressure chamber 27 flows into the reservoir chamber 28 from a minute leak gap formed between the sliding surfaces of the sleeve 25 and the plunger 26, and 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 that adjusts the tension of the belt 4, the spherical portion 16 provided at the tip of the rod 13 is supported by the spherical inner surface 44 of the bearing member 41 attached to the engine block 40. If the bearing member 41 is inclined and the bearing member 41 is inclined, the contact surface between the liner 43 and the spherical portion 16 is displaced to absorb the inclination of the bearing member 41.

  For this reason, the reaction force of the pressing force applied to the bearing member 41 from the hydraulic auto tensioner 10 acts in the axial direction of the rod 13, so that no offset load is applied to the hydraulic auto tensioner 10. Therefore, the hydraulic auto tensioner 10 can be operated with high accuracy, and a decrease in durability can be suppressed.

  In the rod 13 having the spherical portion 16 as described above, if the spring seat 17 that receives the spring force of the return spring 14 is integrated with the rod 13, the shape becomes complicated and difficult to process. Since the spring seat 17 is attached to the rod 13 through the split collet 19, the processing of the rod 13 is easy and the cost can be reduced.

  Further, the spring seat 17 can be easily assembled to the rod 13, and the split collet 19 strongly presses against the outer diameter surface of the rod 13 by the spring force applied from the return spring 14 to the spring seat 17. The spring seat 17 can be firmly attached to the rod 13.

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. An exploded perspective view showing a state before the spring seat is assembled. The perspective view which shows the assembly | attachment state of a spring seat

Explanation of symbols

11 Cylinder 12 Seal member 13 Rod 14 Return spring 15 Hydraulic damper 16 Spherical portion 17 Spring seat 18 Tapered hole 19 Collet 20 Tapered surface 21 Positioning means 22 Engaging groove 23 Projection 24 Flange 40 Engine block 41 Bearing member 44 Spherical inner surface

Claims (3)

  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 spring seat that is incorporated outside the cylinder and has one end provided on the rod. A hydraulic damper that has a return spring supported by a flange provided at the other end of the cylinder and supported at the other end of the cylinder, and is provided with a pushing force in a contracting direction applied to the rod and the cylinder inside the cylinder. In the spring-clad hydraulic auto tensioner that is buffered by the rod, the rod and the spring seat are separated from each other, and the tip of the rod is provided with a spherical portion that is contact-guided by a spherical inner surface on the engine block side. The spring seat is provided below the portion, and two circumferentially between the tapered inner surface of the small-diameter tapered hole at the lower end formed at the center of the spring seat and the outer diameter surface of the rod. Built split by collet, hydraulic auto-tensioner which is characterized in that a matching tapered surface to the tapered inner surface of the tapered hole to the outer periphery of the collet.   The hydraulic auto tensioner according to claim 1, wherein positioning means for positioning the collet in the axial direction is provided between the collet and the rod.   The hydraulic auto tensioner according to claim 2, wherein the positioning means includes an engaging groove formed on the outer periphery of the rod and a protrusion formed on the inner periphery of the collet and engaged with the engaging groove.

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