JP2019173775A - Hydraulic automatic tensioner - Google Patents

Abstract

To provide a hydraulic automatic tensioner in which a phenomenon of oozing-out of a hydraulic fluid from the tensioner hardly occurs.SOLUTION: In a hydraulic automatic tensioner 1 including a rod 12 inserted to a cylinder 11 in a state of being vertically movable, a spring seat 13 disposed on an upper portion of the rod 12, a return spring 14 energizing the rod 12 upward, a hydraulic damper mechanism 15 for buffering downward force applied to the rod 12 by a hydraulic fluid inside of the cylinder 11, and an annular oil seal 16 mounted on an inner periphery of an upper end opening of the cylinder 11 in a manner of being slide-contact therewith in accompany with movement of the rod 12, an oil absorber 34 is disposed at an upper side of the oil seal 16 for absorbing the hydraulic fluid oozing out to an upper part through the slide contact part of the oil seal 16 from the inside of the cylinder 11, and a coil spring 37 is disposed to energize the oil absorber 34 downward toward the oil seat 16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hydraulic auto tensioner that generates a damping force using hydraulic oil.

  An auxiliary machine of an automobile, for example, an alternator, a car air conditioner, a water pump, and the like, is driven through an auxiliary machine belt whose rotating shaft is connected to an engine crankshaft by an auxiliary machine belt. In order to keep the tension of the auxiliary belt within an appropriate range, generally, a pulley arm provided to be swingable about a fulcrum shaft, a tension pulley rotatably attached to the pulley arm, and the tension pulley to the auxiliary belt. A tension adjusting device including an auto tensioner that urges the pulley arm in the pressing direction is used.

  As a hydraulic auto tensioner incorporated in this tension adjusting device, for example, those described in Patent Documents 1 and 2 are known. These hydraulic auto tensioners have a cylinder with an open upper end and a closed lower end, a rod inserted into the cylinder so as to be movable up and down, and a return spring that urges the rod upward. When the tension of the machine belt fluctuates, the rod moves to a position where the tension of the auxiliary machine belt and the biasing force of the return spring balance, and absorbs the fluctuation of the tension of the machine belt.

  The hydraulic auto tensioner has a hydraulic damper mechanism for buffering downward force applied to the rod from the auxiliary belt with hydraulic oil inside the cylinder. In addition, in order to seal the hydraulic oil of the hydraulic damper mechanism in the cylinder, an annular oil seal is attached to the inner periphery of the upper end opening of the cylinder so as to come into sliding contact with the movement of the rod.

Japanese Patent No. 5574229 JP 2012-225447 A

  The hydraulic auto tensioner described above seals hydraulic oil in the cylinder with an oil seal attached to the inner periphery of the upper end opening of the cylinder. However, when a hydraulic auto tensioner is used for a long period of time, a small amount of hydraulic oil leaks from the hydraulic auto tensioner, and the bleeding leak may continue, causing the hydraulic oil to adhere to the auxiliary belt and peripheral parts. It turned out to be. If the hydraulic oil adheres to the auxiliary belt and peripheral parts, it causes slippage of the auxiliary belt and malfunction of the peripheral parts.

  Therefore, the inventors of the present application investigated the cause of a small amount of hydraulic oil spilling and leaking from the hydraulic auto tensioner, and when the rod moves up and down according to the tension fluctuation of the auxiliary belt of the automobile, it accompanies the movement of the rod. It has been found that there is a phenomenon in which hydraulic oil is scraped out at the sliding contact portion of the oil seal, and the hydraulic oil oozes out from the hydraulic auto tensioner due to the scraping action.

  In particular, in recent years, there has been a demand for lower friction of the auxiliary belt in order to reduce the fuel consumption of the vehicle, and accordingly, the tension of the auxiliary belt tends to be set low. On the other hand, the load on the auxiliary machine driven by the auxiliary machine belt tends to increase. For this reason, the amplitude of the auxiliary machine belt tends to increase, and the expansion / contraction stroke of the hydraulic auto tensioner tends to increase, so that the working oil is easily scraped out at the sliding contact portion of the oil seal.

  The problem to be solved by the present invention is to provide a hydraulic auto tensioner that is unlikely to cause a phenomenon in which hydraulic oil leaks from the tensioner.

  In order to solve the above-mentioned problems, in the present invention, a cylinder having an open upper end and a closed lower end, a rod inserted into the cylinder so as to be movable up and down, a spring seat provided on an upper portion of the rod, and the cylinder A return spring that urges the rod upward, and a hydraulic damper mechanism that cushions downward force applied to the rod with hydraulic oil inside the cylinder; An annular oil seal that is attached to the inner periphery of the upper end opening of the cylinder so as to come into sliding contact with the movement of the rod, and is provided above the oil seal, An oil absorber that absorbs hydraulic oil that oozes upward through the sliding contact portion of the oil seal from the oil seal; and Adopting a structure and an elastic member for urging downward toward.

  In this configuration, when the hydraulic oil scraping action occurs at the sliding contact portion of the oil seal accompanying the movement of the rod, the hydraulic oil oozes upward from the inside of the cylinder through the sliding contact portion of the oil seal. The exuded hydraulic oil is absorbed by the oil absorber on the upper side of the oil seal.

  Further, since the oil absorber is biased downward toward the oil seal by the elastic member, the position of the oil absorber can be fixed with respect to the oil seal. For this reason, even when the hydraulic auto tensioner is used over a long period of time, it is possible to prevent the leakage of hydraulic oil from the hydraulic auto tensioner.

  In this configuration, the oil absorber is an annular body disposed on the upper side of the oil seal, and the elastic member is a coil spring disposed along the circumferential direction on the oil absorber. Can do.

  According to this configuration, since the oil absorber is urged downward along the circumferential direction by the coil spring, it is possible to effectively prevent the oil absorber from falling off due to vibration applied to the hydraulic auto tensioner from the outside. Is possible.

  The oil absorber may be composed of a large number of fibers. In this case, since the amount of oil that can be absorbed by the oil absorber is large, it is possible to prevent leakage of hydraulic oil from the hydraulic auto tensioner over a long period of time.

  The hydraulic auto tensioner according to the present invention is an operation that oozes upward from the inside of the cylinder through the sliding contact portion of the oil seal when a working oil scraping action occurs at the sliding contact portion of the oil seal as the rod moves. Oil is absorbed by the oil absorber on the upper side of the oil seal. Therefore, even when the hydraulic auto tensioner is used for a long period of time, it is possible to prevent the leakage of hydraulic oil from the hydraulic auto tensioner.

  Further, the hydraulic oil that has oozed out from the inside of the cylinder through the sliding contact portion of the oil seal is prevented from leaking between the upper portion of the cylinder and the cylindrical portion of the spring seat by the outer lip of the oil seal. .

The front view which shows the tension adjustment apparatus incorporating the hydraulic auto tensioner of 1st embodiment of this invention Sectional view along the line II-II in FIG. 2 is an enlarged cross-sectional view near the oil seal of FIG. Front view showing a tension adjusting apparatus incorporating a hydraulic auto tensioner according to a second embodiment of the present invention. Sectional view along line VV in FIG. FIG. 5 is an enlarged cross-sectional view near the oil seal The expanded sectional view of the oil seal vicinity of the hydraulic auto tensioner according to the embodiment related to the present invention

  FIG. 1 shows a tension adjusting device incorporating a hydraulic auto tensioner 1 according to a first embodiment of the present invention. The tension adjusting device includes a tension pulley 3 that contacts the belt 2, a pulley arm 4 that supports the tension pulley 3, and a hydraulic auto tensioner 1 that biases the pulley arm 4 in a direction to press the tension pulley 3 against the belt 2. Have. The belt 2 is an accessory belt that transmits rotation of a crankshaft (not shown) to an accessory such as an alternator or a water pump.

  The lower connecting piece 5 of the hydraulic auto tensioner 1 is rotatably connected to an engine block 7 (see FIG. 2) via a lower connecting shaft 6. The upper connecting piece 8 of the hydraulic auto tensioner 1 is rotatably connected to the pulley arm 4 via the upper connecting shaft 9. The pulley arm 4 is supported so as to be swingable about a fulcrum shaft 10 fixed to the engine block 7.

  As shown in FIG. 2, the hydraulic auto tensioner 1 includes a cylinder 11, a rod 12 inserted in the cylinder 11 so as to be movable up and down, a spring seat 13 fixed to the upper end of the rod 12, and a spring seat 13. A return spring 14 for urging the rod 12 upward, a hydraulic damper mechanism 15 for buffering the downward force applied to the rod 12 with hydraulic oil inside the cylinder 11, and an inner periphery of the upper end opening of the cylinder 11. And an annular oil seal 16.

  The hydraulic auto tensioner 1 includes an oil absorber 34 provided on an upper portion of the oil seal 16 and a coil spring 37 that is an elastic member incorporated between the spring seat 13 and the oil seal 16.

  The cylinder 11 is formed in a cylindrical shape having an upper end opened and a lower end closed. A lower connecting piece 5 is integrally provided at the lower end of the cylinder 11. The lower connecting piece 5 incorporates a bearing 17 that rotatably supports the lower connecting shaft 6. A flange portion 18 that supports the lower end of the return spring 14 is integrally provided on the outer periphery of the cylinder 11. The cylinder 11 is made of an aluminum alloy.

  The hydraulic damper mechanism 15 includes a steel sleeve 19 fitted in the cylinder 11, a plunger 20 that is slidably inserted into the sleeve 19, and a pressure chamber 21 that is formed below the plunger 20. The reservoir chamber 22 formed on the upper side of the plunger 20, the oil passage 23 communicating between the pressure chamber 21 and the reservoir chamber 22, and the flow of hydraulic oil from the reservoir chamber 22 side to the pressure chamber 21 side of the oil passage 23 Only a check valve 24 that permits only a leak, and a leak gap 25 formed between the sliding surfaces of the plunger 20 and the sleeve 19.

  The pressure chamber 21 is filled with hydraulic oil, and the reservoir chamber 22 contains air and hydraulic oil in upper and lower layers. The oil passage 23 is formed so as to penetrate the plunger 20 vertically. The check valve 24 is disposed at the end of the oil passage 23 on the pressure chamber 21 side. The size of the leak gap 25 is very small, and is set in a range of 0.015 to 0.080 mm as a radial difference between the outer peripheral cylindrical surface of the plunger 20 and the inner peripheral cylindrical surface of the sleeve 19.

  The plunger 20 is biased upward by a plunger spring 26 incorporated in the pressure chamber 21. The plunger 20 supports the lower end of the rod 12, and when the rod 12 moves up and down, the plunger 20 moves up and down integrally with the rod 12.

  A wear ring 27 is attached to the outer periphery of the portion where the rod 12 is inserted into the cylinder 11. The wear ring 27 is guided on the inner periphery of the cylinder 11 so that the position of the rod 12 does not deviate from the center of the cylinder 11. The wear ring 27 is provided with a through hole 28 through which hydraulic oil passes.

  The spring seat 13 includes an upper connecting piece 8 and a flange portion 29 formed on the outer periphery of the lower end of the upper connecting piece 8, and the upper end of the return spring 14 is received by the flange portion 29. The upper connecting piece 8 incorporates a bearing 30 that rotatably supports the upper connecting shaft 9.

  Further, the spring seat 13 has an outer cylindrical portion 31 extending downward from the flange portion 29 so as to face the outer diameter side of the cylinder 11. The outer cylindrical portion 31 is formed so as to cover the outer periphery of the upper portion of the cylinder 11.

  The return spring 14 is a cylindrical coil spring having an inner diameter larger than the outer diameter of the cylinder 11, and is disposed coaxially on the outer diameter side of the cylinder 11.

  As shown in FIG. 3, a cylindrical seal fitting surface 32 having an inner diameter larger than the surface fitted to the sleeve 19 is formed on the inner periphery of the upper end opening of the cylinder 11. The oil seal 16 is fitted with a tightening margin.

  The oil seal 16 includes a cylindrical fitting portion 16a fitted to the seal fitting surface 32, a radially inward flange portion 16b provided on the upper portion of the fitting portion 16a, and an inner peripheral portion of the flange portion 16b. A dust lip 16c provided on the upper side and a seal lip 16d provided on the lower side of the inner peripheral portion of the flange portion 16b are integrally formed from an elastic body.

  The elastic body of the oil seal 16 is made of a synthetic rubber having elasticity excellent in wear resistance and heat resistance. Examples of the synthetic rubber include nitrile rubber, 140 ° C. heat-resistant nitrile rubber, hydrogenated nitrile rubber, acrylic rubber, fluorine rubber, and silicone rubber, among which acrylic rubber and fluorine rubber are particularly preferable.

  The fitting portion 16a and the flange portion 16b of the oil seal 16 are reinforced by a metal core 35 integrally formed therein.

  The oil seal 16 is in a state where the fitting portion 16a is fitted to the seal fitting surface 32 of the cylinder 11 with a tightening margin. The oil seal 16 is in a state where the lower end portion of the fitting portion 16 a is supported by a radial step formed at the lower end portion of the seal fitting surface 32 of the cylinder 11.

  A garter spring 36 is attached to the outer periphery of the seal lip 16d, and the seal lip 16d is fastened to the rod 12 by the garter spring 36. By tightening the garter spring 36, the dust lip 16 c and the seal lip 16 d are in elastic contact with the outer peripheral surface of the rod 12 over the entire circumference, and the oil seal 16 seals the upper end opening of the cylinder 11.

  The oil seal 16 is restricted from moving upward by a retaining ring 33 attached to the seal fitting surface 32 of the upper end opening of the cylinder 11.

  An oil absorber 34 is fixed to the upper surface of the retaining ring 33. The oil absorber 34 is an annular seat disposed above the annular oil seal 16. The oil absorber 34 is composed of a large number of fibers. The inner diameter side end of the oil absorber 34 protrudes more toward the inner diameter side than the inner diameter side end of the retaining ring 33.

  Recycled fibers (such as rayon and acetate) and natural fibers (such as cotton, silk, hemp, and wool) can be used as the fibers constituting the oil absorber 34, but synthetic resin fibers are preferably used. Examples of synthetic resin fibers include polyamide resins such as nylon, aromatic polyamide resins, polyethylene terephthalate, polyethylene naphthalate, polyethylene succinate, and polybutylene terephthalate. When synthetic resin fibers are used, the fibers can be prevented from swelling and dissolving with hydraulic oil, and the cost is low.

  A coil spring 37 which is an elastic member is disposed above the oil absorber 34. The coil spring 37 is attached above the outer periphery of the rod 12 and is disposed between the spring seat 13 and the oil seal 16.

  The coil spring 37 is disposed between the spring seat 13 and the oil seal 16 in a compressed state, and urges the oil absorber 34 downward toward the oil seal 16 via the retaining ring 33 by its elastic restoring force. is doing. The coil spring 37 is disposed along the circumferential direction on an oil absorber 34 that is an annular sheet.

  Next, an operation example of the hydraulic auto tensioner 1 will be described.

  When the tension of the belt 2 shown in FIG. 1 decreases, the rod 12 moves in a direction in which the rod 12 protrudes from the sleeve 19 due to the urging force of the return spring 14, and the slack of the belt 2 is absorbed. At this time, since the volume of the pressure chamber 21 shown in FIG. 2 is enlarged, the check valve 24 is opened, and the hydraulic oil in the reservoir chamber 22 flows into the pressure chamber 21 through the oil passage 23.

  On the other hand, when the tension of the belt 2 shown in FIG. 1 increases, the rod 12 moves in the direction in which the rod 12 is pushed into the sleeve 19 by the tension of the belt 2, and absorbs the tension of the belt 2. At this time, since the volume of the pressure chamber 21 shown in FIG. 2 is reduced, the check valve 24 is closed, the hydraulic oil in the pressure chamber 21 flows out through the leak gap 25, and the damper action is performed by the viscous resistance of the hydraulic oil. Arise.

  By the way, the hydraulic auto tensioner 1 seals the hydraulic oil in the cylinder 11 with an oil seal 16 attached to the inner periphery of the upper end opening of the cylinder 11. Here, when the rod 12 moves up and down according to the tension fluctuation of the belt 2, the hydraulic oil is scraped out at the sliding contact portion (the contact portion between the oil seal 16 and the rod 12) of the oil seal 16 as the rod 12 moves. May occur.

  In particular, in recent years, there has been a demand for low friction of the belt 2 in order to reduce the fuel consumption of the vehicle, and accordingly, the tension of the belt 2 tends to be set low. On the other hand, the load on the auxiliary machine driven by the belt 2 tends to increase. Therefore, the amplitude of the belt 2 tends to increase, and the expansion / contraction stroke of the hydraulic auto tensioner 1 tends to increase, so that the working oil is easily scraped out at the sliding contact portion of the oil seal 16.

  When the hydraulic auto tensioner 1 is used over a long period of time, the hydraulic oil scraped out at the sliding contact portion of the oil seal 16 leaks from the hydraulic auto tensioner 1 and continues to leak. May adhere to the belt 2 and peripheral parts. When the hydraulic oil adheres to the belt 2 and peripheral parts, it causes slippage of the belt 2 and malfunction of peripheral parts.

  In response to this problem, the hydraulic auto tensioner 1 has a sliding contact portion of the oil seal 16 from the inside of the cylinder 11 when a hydraulic oil scraping action occurs in the sliding contact portion of the oil seal 16 as the rod 12 moves. The hydraulic oil that oozes upward through the oil is absorbed by the oil absorber 34 on the upper side of the oil seal 16. Therefore, even when the hydraulic auto tensioner 1 is used over a long period of time, it is possible to prevent the leakage of hydraulic oil from the hydraulic auto tensioner 1.

  Further, since the hydraulic auto tensioner 1 employs the annular oil absorber 34, the hydraulic oil oozing out from any circumferential position of the sliding contact portion of the annular oil seal 16 can be absorbed. For this reason, even if the hydraulic auto tensioner 1 is mounted in a posture inclined in any direction, it is possible to prevent leakage of hydraulic oil from the hydraulic auto tensioner 1.

  Further, since the hydraulic auto tensioner 1 employs a structure composed of a large number of fibers, the amount of oil that can be absorbed by the oil absorber 34 is large. Therefore, it is possible to prevent the leakage of hydraulic oil from the hydraulic auto tensioner 1 over a long period of time.

  The hydraulic auto tensioner 1 biases the oil absorber 34 downward toward the oil seal 16 via a retaining ring 33 by a coil spring 37 that is an elastic member. For this reason, it is possible to effectively prevent the oil absorber 34 from falling off due to vibration applied to the hydraulic auto tensioner 1 from the outside.

  4 to 6 show a hydraulic auto tensioner 1 according to a second embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 5, the hydraulic damper mechanism 15 includes a steel sleeve 40 fixed in the cylinder 11 so as to be in sliding contact with the outer periphery of the rod 12, a pressure chamber 21 formed inside the sleeve 40, and a sleeve. The reservoir chamber 22 formed between the cylinder 40 and the cylinder 11, the oil passage 23 communicating between the pressure chamber 21 and the reservoir chamber 22, and the hydraulic oil from the reservoir chamber 22 side of the oil passage 23 to the pressure chamber 21 side. It consists of a check valve 24 that allows only flow and a leak gap 25 formed between the sliding surfaces of the rod 12 and the sleeve 40. The size of the leak gap 25 is very small, and is set in a range of 0.015 to 0.080 mm as a difference in radius between the outer peripheral cylindrical surface of the rod 12 and the inner peripheral cylindrical surface of the sleeve 40.

  The sleeve 40 is coaxially inserted into the cylinder 11, and the lower outer periphery of the sleeve 40 is press-fitted into a sleeve fitting recess 42 formed on the inner bottom surface 41 of the cylinder 11. The oil passage 23 is formed between the fitting surface of the sleeve fitting recess 42 and the sleeve 40. The check valve 24 is press-fitted into the lower end of the sleeve 40.

  The return spring 14 is a cylindrical coil spring having an outer diameter smaller than the inner diameter of the cylinder 11, and is arranged coaxially on the inner diameter side of the cylinder 11. The lower end of the return spring 14 is supported by the inner bottom surface 41 of the cylinder 11, and the upper end of the return spring 14 presses the spring seat 13 upward.

  The spring seat 13 includes an end plate 43 that receives the upper end of the return spring 14, an upper connecting piece 8 provided so as to protrude upward from the end plate 43, and an end plate 43 that faces the inner diameter side of the cylinder 11. It has an inner cylindrical portion 44 that extends downward, and an outer cylindrical portion 45 that extends downward from the end plate 43 so as to face the outer diameter side of the cylinder 11. The outer cylindrical portion 45 is in a state of covering the outer periphery of the upper portion of the cylinder 11.

  As shown in FIG. 6, a seal fitting surface 32 is formed in the upper end opening of the cylinder 11. The seal fitting surface 32 has an inner diameter larger than that of the inner peripheral surface of the cylinder 11 below the upper end opening portion where the seal fitting surface 32 is formed. An oil seal 16 is fitted to the seal fitting surface 32 with a tightening margin.

  The oil seal 16 includes a cylindrical fitting portion 16 a that fits on the seal fitting surface 32, a radially inward flange portion 16 b provided on the upper portion of the fitting portion 16 a, and a spring as the rod 12 moves. It has a dust lip 16 c and a seal lip 16 d that are in sliding contact with the outer periphery of the inner cylindrical portion 44 of the seat 13.

  The oil seal 16 is in a state where the fitting portion 16a is fitted to the seal fitting surface 32 of the cylinder 11 with a tightening margin. The oil seal 16 is in a state where the lower end portion of the fitting portion 16 a is supported by a radial step formed at the lower end portion of the seal fitting surface 32 of the cylinder 11.

  A garter spring 36 is attached to the outer peripheral portion of the seal lip 16 d, and the seal lip 16 d is fastened to the outer peripheral portion of the inner cylindrical portion 44 by the garter spring 36. By tightening the garter spring 36, the dust lip 16 c and the seal lip 16 d are in elastic contact with the outer peripheral surface of the inner cylindrical portion 44 over the entire periphery, and the oil seal 16 seals the upper end opening of the cylinder 11.

  An oil absorber 34 is fixed to the upper part of the oil seal 16. A coil spring 37 that is an elastic member is disposed above the oil absorber 34. The coil spring 37 is attached above the outer periphery of the inner cylindrical portion 44 and is disposed between the end plate 43 of the spring seat 13 and the oil seal 16.

  The coil spring 37 is disposed between the end plate 43 of the spring seat 13 and the oil seal 16 in a compressed state, and urges the oil absorber 34 downward toward the oil seal 16 by its elastic restoring force. Yes. The coil spring 37 is disposed along the circumferential direction on an oil absorber 34 that is an annular sheet.

  The hydraulic auto tensioner 1 according to the second embodiment can also exhibit the same effects as the first embodiment.

  FIG. 7 shows a hydraulic auto tensioner 1 of a reference example. Portions corresponding to the above-described embodiments are given the same reference numerals and description thereof is omitted. As shown in FIG. 7, the hydraulic auto tensioner 1 of this reference example does not include the oil absorber 34 and the coil push ring 37, and the oil seal 16 has the outer lip 16e. This is different from the hydraulic auto tensioner 1 of the second embodiment. In other configurations, parts corresponding to those of the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  The oil seal 16 of the hydraulic auto tensioner 1 of this reference example has an outer lip 16e that extends radially outward toward the upper part of the fitting portion 16a. The front end edge of the outer lip 16e is located above the upper end edge of the cylinder 11 and radially outside. The outer lip 16e is located above the flange portion 16b.

  The outer lip 16e is formed of an elastic body that forms the oil seal 16, and is formed integrally with the fitting portion 16a. The outer lip 16 e extends toward the inner peripheral portion of the outer cylindrical portion 45 of the spring seat 13, and the tip edge thereof is in elastic contact with the inner peripheral portion of the outer cylindrical portion 45 of the spring seat 13 over the entire circumference. Yes.

  The outer lip 16e in this state is in sliding contact with the inner peripheral portion of the outer cylindrical portion 45 of the spring seat 13 as the rod 12 moves.

  As in the second embodiment, the hydraulic auto tensioner 1 according to the reference example causes a working oil scraping action at the sliding contact portion of the oil seal 16 as the rod 12 moves. When this scraping action occurs, hydraulic oil that has oozed out from the inside of the cylinder 11 through the sliding contact portion of the oil seal 16 (the contact portion between the oil seal 16 and the inner cylindrical portion 44) is removed by the outer lip 16e. It is possible to prevent leakage between the cylinder 11 and the outer cylindrical portion 45 and leaking to the outside of the cylinder 11. Therefore, the outer lip 16e integrated with the oil seal 16 is provided at the upper end of the cylinder 11 and functions as a weir member that prevents leakage of hydraulic oil to the outside of the hydraulic auto tensioner 1.

  The reference example based on FIG. 7 discloses the invention appended below.

(Appendix 1)
A cylinder (11) having an upper end opened and a lower end closed, a rod (12) inserted into the cylinder (11) so as to be movable up and down, and a spring seat (13) provided on an upper portion of the rod (12) And a return spring (14) which is incorporated between the lower part of the cylinder (11) and the spring seat (13) and urges the rod (12) upward, and is loaded on the rod (12). An inner circumference of the upper end opening of the cylinder (11) so as to come into sliding contact with the movement of the rod (12), and a hydraulic damper mechanism (15) for buffering downward force with hydraulic oil inside the cylinder (11). And an annular oil seal (16) attached to the spring seat (13), the spring seat (13) having a cylindrical part (45) covering the outer periphery of the upper part of the cylinder (11), The tool (16) has an outer lip (16e) extending toward the inner peripheral portion of the cylindrical portion (45) of the spring seat (13), and the outer lip (16e) moves the rod (12). Accordingly, the hydraulic auto tensioner is configured to come into sliding contact with the inner peripheral portion of the cylindrical portion (45).

(Appendix 2)
The oil seal (16) is formed of an annular cored bar (35) and an elastic body covering the cored bar (35), and the outer lip (16e) is formed of the elastic body. The hydraulic auto tensioner according to appendix 1.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Hydraulic type auto tensioner 11 Cylinder 12 Rod 13 Spring seat 14 Return spring 15 Hydraulic damper mechanism 16 Oil seal 16a Fitting part 16b Flange part 16d Dustrip 16d Seal lip 16e Outer lip 34 Oil absorber 35 Core metal 37 Coil spring 44 Inner Cylindrical part 45 Outer cylindrical part

Claims (3)

A cylinder (11) whose upper end is open and whose lower end is closed;
A rod (12) inserted into the cylinder (11) so as to be movable up and down;
A spring seat (13) provided on top of the rod (12);
A return spring (14) incorporated between a lower portion of the cylinder (11) and the spring seat (13) and biasing the rod (12) upward;
A hydraulic damper mechanism (15) for buffering downward force applied to the rod (12) with hydraulic oil inside the cylinder (11);
In a hydraulic auto tensioner comprising an annular oil seal (16) attached to the inner periphery of the upper end opening of the cylinder (11) so as to come into sliding contact with the movement of the rod (12),
An oil absorber (34) that is provided above the oil seal (16) and absorbs hydraulic oil that has oozed out from the inside of the cylinder (11) through the sliding contact portion of the oil seal (16); A hydraulic auto tensioner comprising: an elastic member that urges the oil absorber (34) downward toward the oil seal (16).   The oil absorber (34) is an annular body disposed above the oil seal (16), and the elastic member is disposed on the oil absorber (34) along the circumferential direction (37). The hydraulic auto tensioner according to claim 1, wherein   The hydraulic auto tensioner according to claim 1 or 2, wherein the oil absorber (34) is composed of a large number of fibers.

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