JP2008256117A - Hydraulic auto-tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an upper end of a cylinder from being damaged by pushing and widening of a rose retaining ring in a hydraulic auto-tensioner in which an oil seal is prevented from falling out by the rose retaining ring. <P>SOLUTION: The oil seal 14 is assembled in an upper opening of the cylinder 11 filled with operating oil thereinside, and the rose retaining ring 15 is mounted to prevent falling out of the oil seal 14. A hydraulic damper 30 for alleviating pressing force applied on a rod 16 from a belt is provided to a lower part of the rod 16 slidably penetrating the oil seal 14. A return spring 19 for applying outward projecting property to the rod 16 is provided on the outside of the cylinder 11. A ring 40 comprising a steel plate press molded article is press fitted on the outer periphery of an upper end of the cylinder 11 to reinforce the upper end. Therefore, even when a large axial load is applied to the rose retaining ring 15 and a pressing force so as to push and widen the upper end of the cylinder 11 radially outward acts on the cylinder 11 by biting of the rose retaining ring 15, the upper end of the cylinder 11 is prevented from being damaged by the pressing force. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydraulic auto tensioner used for adjusting the tension of a belt for driving an auxiliary machine such as an alternator.

  As this type of hydraulic auto tensioner, one described in Patent Document 1 has been conventionally known. This auto tensioner seals the opening of the cylinder fitted with a steel bottom sleeve with an oil seal to prevent leakage of the hydraulic oil filled inside, and the oil seal can slide freely. An elastic force of a return spring is imparted to the rod penetrating the rod to impart an outward projecting property, and the pushing force applied from the belt to the rod is buffered by a hydraulic damper incorporated in the sleeve.

  In addition, a wear ring that is slidable along the inner diameter surface of the cylinder is attached to a portion of the rod located inside the cylinder, and the wear ring prevents the rod from collapsing.

Here, the oil seal is prevented from moving downward by a step formed on the inner periphery of the cylinder, and is prevented from being pulled out by a retaining ring attached to the upper side thereof.
JP-A-10-19099

  By the way, in the conventional hydraulic auto tensioner, since a C-shaped retaining ring is used as a retaining ring for retaining the oil seal, it is necessary to turn an engagement groove on the inner diameter surface of the cylinder when mounting it. There is a disadvantage that it takes time for processing and time for attaching the retaining ring.

  Further, since the thickness of the cylinder is reduced at the portion where the engagement groove is formed, it is necessary to use a thick cylinder, and there is a disadvantage that the weight of the hydraulic auto tensioner is increased.

  Furthermore, when the belt is cut and the rod moves rapidly outward by the elastic force of the return spring, and the impact force acts on the oil seal due to the contact of the wear ring, the retaining ring is deformed by the impact force, or There is a possibility that the engagement groove is broken and the oil seal cannot be prevented from being pulled out, and there is a disadvantage that the reliability of the retaining is low.

  Therefore, by adopting a chrysanthemum retaining ring instead of the C-shaped retaining ring, this chrysanthemum retaining ring can be brought into the mounted state by being pushed into the inside from the opening of the cylinder. The effect can be improved.

  However, the chrysanthemum retaining ring has a structure in which the outer peripheral edges of a plurality of claw portions formed on the outer periphery thereof are bitten into the inner diameter surface of the cylinder to prevent it from being removed, so that a large axial load is applied when retaining the rod. When a load is applied, the cylinder is strongly bitten into the cylinder inner surface, and the upper end of the cylinder is pushed outward in the radial direction. At this time, if the strength of the cylinder is insufficient, or if the cylinder is formed by die casting and has a relatively low strength, the upper end of the cylinder may be damaged. Although it is effective to increase the thickness of the cylinder to prevent the damage, it cannot be increased due to demands for weight reduction and space saving.

  An object of the present invention is to prevent an upper end portion of a cylinder from being damaged by spreading of a chrysanthemum retaining ring in a hydraulic auto tensioner in which an oil seal is secured by a chrysanthemum retaining ring.

  In order to solve the above problems, in the present invention, an oil seal for preventing leakage of hydraulic oil to the outside in an upper opening of a cylinder filled with hydraulic oil and a chrysanthemum for preventing the oil seal from being removed. A retaining ring is incorporated, and the elastic force of the return spring is applied to the rod that slidably penetrates the oil seal to urge the rod outward, and the pushing force applied to the rod is provided inside the cylinder. In a hydraulic auto tensioner that is buffered by a hydraulic damper, a configuration is adopted in which a ring is provided at the upper end of the cylinder to reinforce the periphery of the engagement portion of the chrysanthemum retaining ring.

  Here, a ring made of a press-formed product of a steel plate provided with an inward flange that can come into contact with the upper end surface of the cylinder at one end of the cylindrical portion fitted to the upper end outer peripheral surface of the cylinder is adopted. If the cylindrical part of the ring is press-fitted into the outer periphery of the upper end of the cylinder, it is possible to take reinforcement measures for the cylinder of the existing hydraulic auto tensioner, and it is easy to manufacture the ring, and the cost is low. A ring can be provided.

  Also, by forging the steel ring during die casting of the cylinder, it is possible to prevent forgetting to assemble the ring when assembling the hydraulic auto tensioner.

  As described above, in the present invention, since a ring is provided at the upper end of the cylinder and reinforced, a large axial load is applied to the chrysanthemum retaining ring when the rod is retained, and the chrysanthemum retaining ring is engaged. Even if a pressing force that pushes the upper end portion of the cylinder radially outward by acting is applied, it is possible to prevent the upper end portion of the cylinder from being damaged by the pressing force.

  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 4 that applies tension to the belt 3 is rotatably supported at the end of the swing side.

  Further, a hydraulic auto tensioner 10 according to the present invention is connected to the pulley arm 1, and the pulley arm 1 is urged by the hydraulic auto tensioner 10 in a direction in which the tension pulley 4 presses the belt 3.

  As shown in FIG. 2, the hydraulic auto tensioner 10 has a bottomed cylindrical cylinder 11 whose upper end is open. The cylinder 11 is made of an aluminum alloy and is filled with hydraulic oil.

  A step portion 12 is formed on the inner peripheral upper portion of the cylinder 11, and the lower surface outer peripheral portion of the wear ring 13 is supported by the step portion 12, and an oil seal 14 that seals the upper opening of the cylinder 11 is incorporated on the wear ring 13. It is.

  As shown in FIG. 3, the oil seal 14 is secured by a retaining ring 15 attached to the upper part of the inner periphery of the cylinder 11. The retaining ring 15 is formed of a chrysanthemum retaining ring, and a plurality of claw portions 15a inclined in the same direction are formed on the outer periphery. The outer edge e at the tip of each claw portion 15a bites into the inner diameter surface of the cylinder 11, The chrysanthemum retaining ring 15 is attached by biting.

  As shown in FIG. 2, a spring seat 17 is attached to an upper end portion of the rod 16 that slidably passes through the chrysanthemum retaining ring 15 and the oil seal 14 and is located outside the cylinder 11. A return spring 19 is provided between the flanges 18 provided at the lower outer periphery to give the rod 16 outward protrusion.

  A connecting piece 20 is formed on the upper surface of the spring seat 17, and the connecting piece 20 is connected to the pulley arm 1 via a bolt 21 screwed into the pulley arm 1. On the other hand, a connecting piece 22 is also provided at the lower end of the cylinder 11, and the connecting piece 22 is connected to the engine block 23 via a bolt 24 screwed into the engine block 23.

  An upper portion of a cylindrical dust cover 25 that covers the upper end opening of the cylinder 11 is supported on the lower surface of the spring seat 17.

  As shown in FIGS. 2 and 4, a hydraulic damper 30 for buffering the pushing force applied to the rod 16 is incorporated in the cylinder 11.

  The hydraulic damper 30 has a small-diameter shaft portion 16 a formed at the lower end portion of the rod 16 fitted with a disc-like valve body 31 and a plunger 32 slidable along the inner diameter surface of the cylinder 11 below. The valve body 31 is fixed to the small-diameter shaft portion 16a, and the plunger 32 is slidable between the retaining ring 33 attached to the lower end portion of the small-diameter shaft portion 16a and the valve body 31, and the plunger 32 is disposed below the plunger 32. A passage 36 is provided to communicate the formed pressure chamber 34 with the reservoir chamber 35 provided above, and when the rod 16 is pushed and the pressure in the pressure chamber 34 rises, the plunger 32 is slid upward and the valve body 31 is moved. The valve body 31 closes the passage 36 so that the pressing force applied to the rod 16 by the hydraulic oil sealed in the pressure chamber 34 is buffered.

  As shown in FIG. 3, the upper end portion of the cylinder 11 is reinforced by attaching a ring 40. The ring 40 is a press-formed product of a steel plate in which an inward flange 42 capable of abutting with the upper end surface of the cylinder 11 is formed at the upper end of the cylindrical portion 41 fitted to the outer periphery of the upper end portion of the cylinder 11. The cylindrical portion 41 is press-fitted into the outer periphery of the upper end portion of the lens.

  The belt tension adjusting device shown in the embodiment has the above-described structure, and the tension of the belt 3 changes due to the load fluctuation of the auxiliary machine driven by the belt 3 and the change of the angular velocity of the crankshaft, and the belt 3 is slack. When this occurs, the rod 16 moves outward by the pressure of the return spring 19 and absorbs the slack of the belt 3.

  At this time, since the plunger 32 also moves in the same direction as the rod 16, the volume of the pressure chamber 34 increases and the pressure decreases. When the pressure becomes lower than the pressure of the reservoir chamber 35, the plunger 32 slides downward. As a result, the passage 36 opens. Therefore, the hydraulic oil in the reservoir chamber 35 flows from the passage 36 to the pressure chamber 34, and the rod 16 and the plunger 32 move rapidly outward to immediately absorb the slack of the belt 3.

  On the other hand, when the tension of the belt 3 increases, a pushing force is applied from the belt 3 to the rod 16. At this time, since the pressure in the pressure chamber 34 becomes higher than the pressure in the reservoir chamber 35, the plunger 32 slides upward so that the upper surface thereof is in close contact with the lower surface of the valve body 31, and the passage 36 is closed by the valve body 31. The pushing force applied to the rod 16 is buffered by the hydraulic oil sealed in the pressure chamber 34.

  When the pushing force is larger than the elastic force of the return spring 19, the hydraulic oil in the pressure chamber 34 flows into the reservoir chamber 35 through a minute leak gap formed between the sliding surfaces of the cylinder 11 and the plunger 32, and the pushing force and The rod 16 is slowly retracted to a position where the elastic force of the return spring 19 is balanced, and the tension of the belt 3 is kept constant.

  When the tension of the belt 3 is adjusted as described above, if the rod 16 is rapidly moved outward due to the belt 3 being broken or the like, the plunger 32 collides with the wear ring 13 and the oil seal 14 is removed. An impact force is applied to the retaining ring 15 to be stopped.

  At this time, the chrysanthemum retaining ring 15 is applied with a pressing force such that the claw portion 15a is strongly engaged with the inner peripheral surface of the cylinder 11 due to the axial load applied, and the upper end portion of the cylinder 11 is pushed radially outward. And when the intensity | strength of the upper end part of the cylinder 11 is insufficient, the upper end part may be damaged.

  However, since the upper end portion of the cylinder 11 is reinforced by the attachment of the ring 40, the upper end portion of the cylinder 11 is not damaged.

  Here, since the ring 40 is attached by press-fitting, it is possible to reinforce the cylinder of the existing auto tensioner. Moreover, since the ring 40 is a press-formed product of a steel plate, it is easy to manufacture and low in cost. A ring 40 can be provided.

  In the embodiment, as described above, the ring 40 is press-fitted into the outer periphery of the upper end portion of the cylinder 11 to reinforce the upper end portion. However, when the cylinder 11 is die-casted with an aluminum alloy, a hard steel plate or the like is used. A ring formed of the above material may be insert-molded. At this time, it is possible to prevent forgetting to assemble the ring when the hydraulic auto tensioner is assembled.

Front view of belt tension adjusting device using hydraulic auto tensioner according to the present invention 1 is a longitudinal front view of the hydraulic auto tensioner shown in FIG. Sectional view showing the mounting part of the chrysanthemum retaining ring on an enlarged scale Sectional view showing enlarged hydraulic damper

Explanation of symbols

11 Cylinder 14 Oil seal 15 Chrysanthemum retaining ring 16 Rod 19 Return spring 30 Hydraulic damper 40 Ring

Claims (3)

An oil seal that prevents leakage of the hydraulic oil to the outside and a chrysanthemum retaining ring that prevents the oil seal from being inserted into the upper opening of the cylinder filled with hydraulic oil, and slidably penetrates the oil seal. In the hydraulic auto tensioner that applies the elastic force of the return spring to the rod to urge the rod outward, and the pushing force applied to the rod is buffered by the hydraulic damper provided inside the cylinder,
A hydraulic auto tensioner characterized in that a ring is provided at the upper end of the cylinder to reinforce the periphery of the engaging portion of the chrysanthemum retaining ring.   The ring is made of a press-formed product of a steel plate provided with an inward flange that can come into contact with the upper end surface of the cylinder at one end of the cylindrical portion fitted to the outer peripheral surface of the upper end of the cylinder. The hydraulic auto tensioner according to claim 1, wherein the hydraulic auto tensioner is press-fitted into the outer periphery of the upper end portion of the lip.   The hydraulic auto tensioner according to claim 1, wherein the ring is insert-molded at the time of cylinder die-cast molding.

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