JP2007211852A - Hydraulic automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic automatic tensioner, easy in assembling, while surely preventing slipping-out of an oil seal. <P>SOLUTION: Slipping-out is prevented by installing a retaining ring 15 by incorporating the oil seal 13 into an upper opening of a cylinder 11 of filling a hydraulic fluid inside. A shock absorbing hydraulic damper 30 of pushing-in force applied to a rod 16 from a belt, is arranged in a lower part of the rod 16 slidingly penetrating through its oil seal 13. A return spring 19 is arranged outside the cylinder 11 for imparting projecting performance in the outward direction to the rod 16. A plurality of claw parts 15a are provided on the outer periphery as the retaining ring 15 for preventing the slipping-out of the oil seal 13. The oil seal 13 is prevented from slipping out by holding the rose retaining ring 15 in an installation state by biting-in of a burr (d) to an inner diameter surface of the cylinder 11, by adopting the press-molded rose retaining ring of forming the burr (d) in a shearing cut end 15b of its claw parts 15a. <P>COPYRIGHT: (C)2007,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 deformation such as bending of the rod.

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.

  Further, when the belt is cut and the rod is rapidly moved outward by the elastic force of the return spring and an impact force is applied to the oil seal by the contact of the wear ring, the retaining ring is deformed or engaged by the impact force. There is a possibility that the mating groove is broken and the oil seal cannot be prevented from being pulled out.

  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. Although the above-mentioned chrysanthemum retaining ring has a structure in which the outer peripheral edges of the plurality of claw portions formed on the outer periphery thereof are bitten into the inner diameter surface of the cylinder to prevent the removal, In order to enhance the effect, it is necessary to post-process the nail part after press forming by shearing and bending to sharpen the edge of the outer periphery of the nail part, which causes a problem that it takes a lot of work.

  An object of the present invention is to provide a hydraulic auto tensioner that is easy to assemble so that an oil seal can be securely removed.

  In order to solve the above problems, in the present invention, a cylinder filled with hydraulic oil, an oil seal that seals the upper opening of the cylinder in a state where an air reservoir is formed on the hydraulic oil, A rod that slidably penetrates the oil seal, a return spring that imparts outward protrusion to the rod, a hydraulic damper that cushions the pushing force applied to the rod, and an internal cylinder. In a hydraulic auto tensioner comprising a wear ring that supports both ends of the rod, a retaining ring is mounted in the upper opening of the cylinder, and the oil seal is prevented from being removed by the retaining ring. A plurality of claw portions inclined in the same direction formed by bending of the claw portion on the outer periphery, and by biting into the cylinder inner surface of each claw portion Consists chrysanthemum-shaped retaining ring that is press-molded are attached state is the return to form the pawl portions of the chrysanthemum-shaped retaining ring shear cut have adopted the bending processed configured to be positioned outside.

  As described above, by removing the oil seal with the chrysanthemum retaining ring, the chrysanthemum retaining ring is pushed into the cylinder from above the top opening of the cylinder, so that the outer edge of the claw is brought into contact with the inner diameter surface of the cylinder. Since it is bitten and attached, it is easy to incorporate, and the edge of the outer periphery of the claw is a burr formed during shearing, so it is sharp and the claw is placed against the inner diameter surface of the cylinder. It can be firmly bitten and the oil seal can be securely removed.

  In addition, since it is not necessary to process the engagement groove in the cylinder, the processing can be facilitated and a thin cylinder can be adopted, so that the weight of the hydraulic auto tensioner can be reduced. be able to.

  Further, when press-molding the chrysanthemum retaining ring, a sharp edge is obtained on the outer side of the nail part by bending the nail part so that the burr formed on the shear cut at the outer periphery of the nail part is located outside. Therefore, there is no need to post-process the claw after press molding, and a chrysanthemum retaining ring that is easy to manufacture and inexpensive can be obtained.

  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 for applying tension to the belt 3 is rotatably supported at the end of the swing side. .

  The pulley arm 1 is connected to a hydraulic auto tensioner 10 according to the present invention, 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 a steel bottomed cylindrical sleeve 12 is fitted therein.

  The inside of the cylinder 11 is filled with hydraulic oil, and the hydraulic oil is prevented from leaking to the outside by an oil seal 13 that seals the upper opening of the cylinder 11. As shown in FIG. 3, the oil seal 13 is supported at the outer peripheral portion of the lower surface by a step portion 14 formed at the inner peripheral upper portion of the cylinder 11, and an air pocket is formed between the oil seal 13 and the hydraulic oil surface. Has been. Further, the oil seal 13 is secured by a retaining ring 15 attached to the upper 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.

  The chrysanthemum retaining ring 15 comprises a press-formed product formed by shearing and bending after the shearing. FIG. 4 shows a blank A of the chrysanthemum retaining ring 15 formed by shearing, and the shear cut 15b of the claw portion 15a is formed with a wholly a, a sheared surface b, a fractured surface c, and a burr d. d forms an extremely sharp edge e.

  As shown in FIG. 5, the claw portion 15a after the shearing is bent in the same direction so that the burr d is arranged on the outside, and the chrysanthemum retaining ring 15 is formed by the bending.

  As shown in FIG. 2, a spring seat 17 is attached to an upper end portion of the rod 16 slidably passing through the chrysanthemum retaining ring 15 and the oil seal 13 and 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.

  A hydraulic damper 30 is incorporated in the sleeve 12 to buffer the pushing force applied to the rod 16.

  The hydraulic damper 30 connects a plunger 31 slidable along the inner diameter surface of the sleeve 12 to the lower end of the rod 16 to partition the inside of the sleeve 12 into a pressure chamber 32 and a reservoir chamber 33. A passage 34 communicating with the pressure chamber 32 and the upper reservoir chamber 33 is provided, and the passage 34 is closed at the opening of the passage 34 on the pressure chamber 32 side when the pressure in the pressure chamber 32 becomes higher than the pressure in the reservoir chamber 33. The check valve 35 is provided to buffer the pushing force applied to the rod 16 by the hydraulic oil sealed in the pressure chamber 32. Reference numeral 36 denotes a plunger spring that presses the plunger 31 against the lower end of the rod 16.

  The rod 16 has a configuration in which a small-diameter shaft portion 16b is provided at the lower end of the large-diameter shaft portion 16a, and the wear ring 37 fitted to the small-diameter shaft portion 16b is slidable along the inner diameter surface of the cylinder 11. The middle portion of the rod 16 in the length direction is supported by the wear ring 37.

  An engagement groove 38 is formed in the small diameter shaft portion 16b at a position facing the lower surface of the wear ring 37 in a state where the wear ring 37 is in contact with the lower end of the large diameter shaft portion 16a, and is attached to the engagement groove 38. The wear ring 37 is supported in a non-movable manner in the axial direction by the circlip 39 and the lower end surface of the large-diameter shaft portion 16a.

  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 31 also moves in the same direction as the rod 16, the volume of the pressure chamber 32 increases and the pressure decreases. When the pressure becomes lower than the pressure of the reservoir chamber 33, the check valve 35 opens the passage 34. Therefore, the hydraulic oil in the reservoir chamber 33 flows from the passage 34 to the pressure chamber 32, and the rod 16 and the plunger 31 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 32 becomes higher than the pressure in the reservoir chamber 33, the check valve 35 closes the passage 34, and the pushing force applied to the rod 16 by the hydraulic oil sealed in the pressure chamber 32 is increased. Buffered.

  When the pushing force is larger than the elastic force of the return spring 19, the hydraulic oil in the pressure chamber 32 flows into the reservoir chamber 33 through a minute leak gap formed between the sliding surface of the sleeve 12 and the plunger 31, 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 belt 3 is broken, the rod 16 is rapidly moved outward by the pressing of the return spring 19, and the wear ring 37 comes into contact with the oil seal 13. Impact force is applied.

  At this time, the chrysanthemum retaining ring 15 for retaining the oil seal 13 is mounted so that the burr d formed on the shear cut 15b of the claw portion 15a bites into the inner diameter surface of the cylinder 11, so that the oil seal 13 has an impact force. When loaded, the burr d as a sharp edge of the claw portion 15a bites into the inner diameter surface of the cylinder 11 more strongly, and receives the impact force applied to the oil seal at the biting portion.

  For this reason, the oil seal 13 can be surely prevented from being pulled out, and the components of the hydraulic auto tensioner can be prevented from being separated.

  Here, when the chrysanthemum retaining ring 15 is pushed into the inside of the cylinder 11 from above the open end of the cylinder 11, the plurality of claw portions 15 a are elastically deformed inward by contact with the inner diameter surface of the cylinder 11, and due to its restoring elasticity. Since the burr d as the outer edge at the tip of the claw portion 15a bites into the inner diameter surface of the cylinder 11, it can be attached very easily.

  Further, since the chrysanthemum retaining ring 15 is attached by biting the burr d as described above, it is not necessary to process the engagement groove in the cylinder 11, and the processing can be facilitated. Since a thin-walled material can be used as the hydraulic auto tensioner, it is possible to reduce the weight of the hydraulic auto tensioner.

  Further, when the chrysanthemum retaining ring 15 is press-molded, the claw portion 15a is bent so that the burr d formed on the shear cut 15b on the outer periphery of the claw portion 15a is located on the outer side. Therefore, it is not necessary to post-process the claw portion 15a after press molding, and the chrysanthemum retaining ring 15 that is easy to manufacture and inexpensive can be obtained.

  In FIG. 2, a wear ring sliding type hydraulic auto tensioner in which the wear ring 37 moves together with the rod 16 is shown, but the hydraulic auto tensioner is not limited to this. For example, as shown in FIG. 6 (I), a wear ring fixing type hydraulic auto tensioner in which a wear ring 37 is assembled between an oil seal 13 and a stepped portion 14 to support the rod 16 slidably. Also good.

  2 and 6 (I) show the upper suction type auto tensioner in which the hydraulic oil in the reservoir chamber 33 is caused to flow into the pressure chamber 32 from the passage 34 provided in the plunger 31. 6 (II), the lower suction type hydraulic oil in the reservoir chamber 33 is caused to flow into the lower portion in the pressure chamber 32 from the passage 40 formed between the fitting surfaces of the cylinder 11 and the sleeve 12. An auto tensioner may be used.

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 a portion of the chrysanthemum retaining ring blank after shearing Sectional drawing of the state which bent the nail | claw part of the blank of FIG. (I) and (II) are sectional views showing other examples of hydraulic auto tensioners

Explanation of symbols

11 Cylinder 13 Oil seal 15 Chrysanthemum retaining ring 15a Claw portion 16 Rod 19 Return spring 30 Hydraulic damper

Claims (1)

A cylinder filled with hydraulic oil, an oil seal that seals the upper opening of the cylinder in a state where an air pocket is formed on the hydraulic oil, a rod that slidably penetrates the oil seal, and a rod It consists of a return spring that imparts outward projecting properties, a hydraulic damper that cushions the pushing force applied to the rod, and a wear ring that is built into the cylinder and supports between both ends of the rod, In the hydraulic auto tensioner in which a retaining ring is attached in the upper opening of the cylinder, and the oil seal is retained by the retaining ring.
The retaining ring has a plurality of claw portions inclined in the same direction formed by bending after shearing on the outer periphery, and is press-formed chrysanthemum that is attached by biting into the cylinder inner surface of each claw portion. A hydraulic auto-tensioner comprising a retaining ring, wherein each claw portion of the chrysanthemum retaining ring is bent with a burr formed on a shear cut surface on the outside.

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