JP2018021597A - Hydraulic auto-tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic auto-tensioner and a hydraulic auto-tensioner unit capable of reducing sliding resistance of an oil seal while preventing oil leakage in use of the hydraulic auto-tensioner, and achieving excellent damping property.SOLUTION: One oil seal 2 is mounted on an inner upper portion of a cylinder 1 of a hydraulic auto-tensioner in a manner of being fitted and fixed, and an inserted rod 3 is slidably kept into contact with a seal lip 2a of the oil seal 2 composed of a rubber elastic material. Fine recessed portions or projecting portions of a lattice pattern 11 and the like or linear arrangement or dotted arrangement applying both, or an oil retaining mechanism of a sliding surface by a flocked layer, is disposed on a surface of the seal lip 2a as the sliding face of the oil seal 2 or a sliding mate such as a rod 3. Thus run-out of a working fluid on the sliding face increased in pressure contact force can be prevented, the working fluid can be sufficiently supplied, and sliding resistance can be reduced.SELECTED DRAWING: Figure 1

Description

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

  Generally, a hydraulic auto tensioner is used for tension adjustment of a belt that drives an auxiliary machine of an automobile. As a main structure, a cylinder, a rod inserted into the cylinder, and the rod and the cylinder are extended. 2. Description of the Related Art A hydraulic auto tensioner having a compression spring that applies an elastic force in a direction and a hydraulic damper mechanism that buffers a pushing force applied to a rod is well known.

  The hydraulic auto tensioner C shown in FIG. 10 is provided with a plunger 104 via an oil seal 122 that holds hydraulic oil and air in a cylinder 101 that is open at the upper end and closed at the lower end and is held on the inner upper portion of the cylinder 101. The rod 103 is slidably inserted, a pressure chamber 106 is provided below the plunger 104 that moves up and down in the cylinder 101, and the hydraulic oil communicates from the pressure chamber 106 to a space in contact with the oil seal 122 via the oil passage 107. The reservoir chamber 108 is provided, and the oil passage 107 allows the flow of hydraulic oil to the pressure chamber having the same pressure or lower as the reservoir chamber 108, and the pressure in the pressure chamber is higher than the pressure in the reservoir chamber 108. A check valve 109 for closing the oil passage is interposed, and the plunger 104 and the cylinder 101 are elastically moved in the direction of being extended by the compression spring 110. It is provided to urge the manner (Patent Document 1).

  Further, referring to FIG. 9 which is a front view of the hydraulic auto tensioner unit of the embodiment, the auto tensioner unit is supported by a pulley arm 18 supported by a fulcrum shaft 28 in a swingable manner in a housing of an engine or an auxiliary machine. A tension pulley 19 is rotatably attached to the swing side end of the belt, and a constant tension is applied to the belt 20 via the tension pulley 19 by a hydraulic auto tensioner connected to the pulley arm 18.

  That is, when the tension of the belt 20 increases, the pulley arm 18 swings counterclockwise about the fulcrum shaft 28. As shown in FIG. 10, the pulley arm 18 pushes down the rod 103 against the cylinder 101 that is supported so as not to move up and down, so that the pressure in the pressure chamber 106 increases, and the check valve 109 closes the oil passage 107, The push-down force of the rod 103 is buffered by the hydraulic oil in 106.

  When the rod 103 is further pushed down, the hydraulic oil in the pressure chamber 106 leaks into the reservoir chamber 108 from the leak gap L between the sliding portions of the plunger 104 and the sleeve 105, and the rod 103 slowly descends, When the pressing force balances with the spring force of the compression spring 110, the rod 103 stops.

When the belt 20 (see FIG. 9) is loosened, the rod 103 is raised relative to the cylinder 101 by the spring force of the compression spring 110. At this time, since the pressure in the pressure chamber 106 becomes lower than the pressure in the reservoir chamber 108, the check valve 109 opens the oil passage 107, and the hydraulic oil in the reservoir chamber 108 flows from the oil passage 107 into the pressure chamber.
Therefore, the rod 103 rapidly moves upward, and the pulley arm 18 shown in FIG. 9 swings at a constant speed toward the belt tension side to absorb the looseness of the belt 20.

  As shown in FIG. 10, the hydraulic auto tensioner C that operates as described above is made of rubber in which the oil seal 122 is in contact with the outer circumference of the annular metal core 116 and the rod 103 in order to improve the sealing performance by the oil seal. Lip 122a and a garter spring 117 for tightening the lip 122a radially inward.

JP-A-9-177913

  However, in the conventional hydraulic auto tensioner C described above, if the tightening force in the radial direction of the seal lip is enhanced by using a garter spring or the like in order to improve the sealing performance by the oil seal, the lubricating oil slides. The surface tends to be insufficient, and the problem of increased frictional resistance during sliding tends to occur.

Further, it is necessary to reduce the sliding characteristics in order to improve the characteristics (damping characteristics) of the damper mechanism of the hydraulic auto tensioner.
Therefore, the object of the present invention is to solve the above-mentioned problems and prevent oil leakage when using the hydraulic auto tensioner, while at the same time reducing the sliding resistance of the oil seal, and has excellent damping characteristics and sealing properties. The hydraulic auto tensioner and the hydraulic auto tensioner unit can achieve the above.

  In order to solve the above-mentioned problems, in the present invention, a rod with a plunger is provided through an oil seal that holds hydraulic oil and air in a cylinder having an upper end opened and a lower end closed, and held on the inner upper portion of the cylinder. Is slidably inserted, and a pressure chamber is provided below the plunger that moves up and down while forming a leak gap in the cylinder, and communicates from the pressure chamber to the oil-sealed space via an oil passage. A hydraulic oil reservoir chamber is provided, and the oil passage allows the hydraulic oil to flow into a pressure chamber having a pressure equal to or lower than that of the reservoir chamber, and the pressure in the pressure chamber is higher than the pressure in the reservoir chamber. In the hydraulic auto tensioner provided with a check valve for closing, the plunger and the cylinder are elastically biased in the direction of extension by a compression spring, the oil seal The provided with 1 or more, and to that with the one or more oil seal or hydraulic auto-tensioner having a coercive oil mechanism of the sliding surface in both sliding partners or their.

  The hydraulic auto tensioner of the present invention configured as described above is provided with a predetermined structure for performing a necessary function, and is provided at the swing side end portion of the arm that is swingably supported by the fixed portion. The tension pulley is rotatably attached, and the auto tensioner unit is operated so that a constant tension is applied to the belt via the tension pulley by the auto tensioner connected to the pulley arm.

  That is, when the belt tension of the belt transmission mechanism suddenly increases, the pressure of the pressure chamber increases when the pulley arm supported swingably on the fixed portion pushes the rod against the cylinder, and the check valve is The rod pushing-down force is buffered by the hydraulic oil in the pressure chamber.

  When the rod is further pushed down, the hydraulic fluid in the pressure chamber leaks into the reservoir chamber from the leak gap between the sliding portion of the plunger and the sleeve, the rod descends slowly, and the force that pushes down the rod and the spring force of the compression spring When and balance, the cylinder stops.

When the belt is loosened, the rod is moved upward by the compression spring. At this time, since the pressure in the pressure chamber becomes lower than the pressure in the reservoir chamber, the check valve opens the oil passage, and the hydraulic oil in the reservoir chamber flows into the pressure chamber from the oil passage.
For this reason, the rod rapidly moves upward, and the pulley arm swings at a constant speed toward the belt tension side to absorb the slack of the belt.

  In the present invention, one or more oil seals are provided to prevent leakage of hydraulic oil used in the auto tensioner that operates as described above, and the outer peripheral surface of the rod or the rod that is the sliding partner of such an oil seal or the rod is provided. Supply of hydraulic oil for liquid lubrication to the sliding surface even if the pressure contact force of the oil seal is increased by providing a sliding surface oil retaining mechanism on the skirt part or both provided integrally with the supporting spring seat Is carried out abundantly and sliding resistance is reduced.

The oil seal is preferably an oil seal made of an elastic material and having one or more seal lips in order to efficiently supply as much hydraulic oil as possible to the sliding surface with increased pressure contact force.
The sliding partner provided with the oil retaining mechanism of the sliding surface may be a skirt portion provided integrally with a rod or a spring seat supporting the rod.

  What is preferable as the oil retaining mechanism for the sliding surface is a linear array or a dotted array using minute recesses or protrusions provided on the surface of the oil seal or its sliding partner or both, or a combination of both.

When such a linear array or punctiform arrangement of minute uneven portions is formed in the oil seal or its sliding partner, a slight gap-shaped passage is formed between the oil seal and the sliding partner, The hydraulic oil retained through the passage is supplied to the sliding surface, and the sliding resistance is reduced by improving the lubricity.
In addition, since the sliding surface on which the linear array or the dot array of minute uneven portions is formed has a smaller frictional force even when the sliding area is reduced, the sliding characteristics can be further improved.

  Further, the oil retaining mechanism for the sliding surface can employ a structure in which a flock layer is provided on the surface including the seal lip of the oil seal. In this case, the amount of hydraulic oil retained in the seal lip is significantly increased. This makes it possible to improve lubricity and reduce sliding resistance.

  In the above case, the fluid is sufficiently liquid lubricated with the hydraulic oil that has exuded from the flocking layer, so that it is possible to increase the rigidity of the seal lip so as to increase the sealing performance as much as possible, and the clamping force against the rod Even if it raises, sliding resistance hardly increases.

  Further, the oil retaining mechanism of the sliding surface is configured such that the oil seal is composed of a first oil seal and a second oil seal disposed adjacently below the first oil seal, and the second oil seal is a communication vent. In order to stably improve the sealing performance of the oil seal, it is preferable to employ a configuration that is a ring-shaped oil seal formed of a porous material having a slag.

  When the second oil seal is formed of a porous material having continuous air holes in this way, the porous material supplies the hydraulic oil to the sliding surface while mitigating the impact force caused by the collision of the hydraulic oil. Even in harsh usage environments, the sliding resistance can be reduced by lowering the pressure contact force against the sliding counterpart by the seal lip.

  In addition, by adopting a configuration in which the second oil seal is an oil seal in which a flock layer is provided on the inner peripheral surface in the same manner as described above, the flock layer is also disposed on the first oil seal disposed adjacent to the second oil seal. Since the lubricity of the hydraulic oil held in the cylinder can be given, the retention amount of the hydraulic oil with respect to the first oil seal can be greatly increased, thereby improving the lubricity and reducing the sliding resistance. Is possible.

  As the porous material acting in this manner, a porous material made of metal, rubber or resin can be employed.

  The present invention provides a hydraulic auto-tensioner that can slide a rod with a plunger through an oil seal held on the inside upper part of a cylinder as described above. Since the oil retaining mechanism for the sliding surface is provided, the tightening force on the outer peripheral surface of the rod is strengthened to prevent oil leakage in order to improve the oil sealing performance, while at the same time reducing the sliding resistance of the oil seal. And has the advantage of being a hydraulic auto tensioner that can achieve excellent damping characteristics.

Sectional drawing which shows the hydraulic auto tensioner of 1st Embodiment (A) A cross-sectional view showing an enlarged main part of FIG. 1, (b) a cross-sectional view showing an enlarged main part of the oil seal of FIG. (A) Sectional drawing which expands and shows the principal part of 2nd Embodiment, (b) Front view which expands and shows the rod of 2nd Embodiment (A) Sectional drawing which expands and shows the principal part of 3rd Embodiment, (b) Sectional drawing which expands and shows the principal part of the oil seal of 3rd Embodiment, (c) Enlarging the rod of 3rd Embodiment Front view (A) Cross-sectional view showing enlarged main parts of the fourth embodiment, (b) Cross-sectional view showing enlarged main parts of the oil seal of the fourth embodiment, (c) Oil seal of the fifth embodiment Sectional view showing enlarged main part Sectional drawing which expands and shows the principal part of 6th Embodiment Sectional drawing which expands and shows the principal part of 7th Embodiment Sectional drawing which expands and shows the principal part of 8th Embodiment Front view of hydraulic auto tensioner unit of embodiment Sectional view showing a conventional hydraulic auto tensioner

Embodiments of the present invention will be described below with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, the hydraulic auto tensioner A according to the first embodiment contains hydraulic oil and air in a cylinder 1 having an upper end opened and a lower end closed. The oil seal 2 is fitted and fixed, and the inserted rod 3 is slidably in contact with the seal lip 2a of the oil seal 2 made of a rubber-like elastic material, and the plunger 4 is attached to the tip of the rod 3. ing.

  The plunger 4 is provided with a diameter that moves up and down while forming a leak gap L with a sleeve 5 separately incorporated inside the cylinder 1, a pressure chamber 6 is provided below the plunger 4, and oil is provided from there. A hydraulic oil reservoir chamber 8 is provided so as to communicate with the space where the oil seal 2 is located via the passage 7.

  The oil passage 7 is a check valve that allows the flow of hydraulic oil to a pressure chamber having the same pressure or lower as the reservoir chamber 8 and closes the oil passage 7 in a state where the pressure in the pressure chamber is higher than the pressure in the reservoir chamber 8. 9 is interposed. Further, the plunger 4 and the cylinder 1 are urged by a compression spring 10 so that they are stretched to a certain length.

  In such a hydraulic auto tensioner A, the surface of the seal lip 2a, which is the sliding surface of the oil seal 2, has a minute uneven circular dot having a height of about 1 mm or less, a convex shape or a similar minute depth. A lattice-like pattern 11, which is also called a texture in which grooves such as V-grooves are linearly arranged, is formed.

  In the hydraulic auto tensioner A, a compression spring 10 is mounted on the outside of the cylinder 1, and a lower end thereof is supported by a flange 12 provided at a lower end portion of the cylinder 1. The upper end of the compression spring 10 is supported by a spring seat 13, and this spring seat 13 is held in a state where the tip of the rod 3 is fitted in the insertion hole 14. Note that reference numeral 15 in FIG. 1 denotes a ring-shaped positioning member that is held by the rod 3 and moves up and down integrally within the cylinder 1.

A check valve 9 made of a check ball is provided at the lower end opening of the plunger 4 in the oil passage 7 that penetrates from the upper end to the lower end of the plunger 4 and communicates with the pressure chamber 6. Supported by S.
The oil seal 2 has a substantially double annular shape as a whole, and an elastic seal member, which is a main constituent material, is reinforced with a coaxial annular cored bar 16, and is further moderately applied to the surface of the rod 3 by a garter spring 17. The seal lip 2a is elastically pressed against each other.

  At least one inward seal lip 2a is formed on the inner peripheral portion of the elastic seal member. Such a seal lip 2a is elastically brought into contact with the surface of the rod 3 to seal between the opposing portions, and is preferably formed of rubber having excellent flexibility and wear resistance. Examples of such rubber include nitrile rubber, acrylic rubber, and fluoro rubber.

  As shown in FIG. 9, in the hydraulic auto tensioner A of the first embodiment, a tension pulley 19 is rotatably attached to a swing side end of a pulley arm 18 that is swingably supported by a support shaft 28. The auto tensioner unit can be used in such a manner that it is connected to 18 and attached to the belt 20 via a tension pulley 19.

  In use, when the tension of the belt 20 of the belt transmission mechanism suddenly increases, the pulley arm 18 swingably supported by the support shaft 28 pushes down the rod 3 (refer to FIG. 1 below), and the pressure in the pressure chamber 6 is reduced. The check valve 9 closes the oil passage 7 and the pushing force of the rod 3 is buffered by the hydraulic oil in the pressure chamber 6.

  When the rod 3 is further pushed down, the hydraulic oil in the pressure chamber 6 leaks into the reservoir chamber 8 from the leak gap L between the sliding portions of the plunger 4 and the sleeve 5, as shown in FIG. The rod 3 stops when the force of pushing down the rod 3 and the spring force of the compression spring 10 balance with each other.

  Further, when the belt 20 (see FIG. 9) is loosened, the rod 3 moves upward by the extension of the compression spring 10. At this time, since the pressure in the pressure chamber 6 becomes lower than the pressure in the reservoir chamber 8, the check valve 9 opens the oil passage 7, and the hydraulic oil in the reservoir chamber 8 flows from the oil passage 7 into the pressure chamber 6.

For this reason, the rod 3 rapidly moves upward, that is, the hydraulic auto tensioner A expands, and the pulley arm 18 (see FIG. 9) swings at a constant speed toward the belt tension side to absorb the looseness of the belt 20.
During such an operation, as shown in FIG. 2, a slight gap-shaped passage is formed between the oil seal 2 and the rod 3 due to the lattice pattern 11 formed of a linear array of uneven portions formed in the oil seal 2. Since it is formed, the hydraulic oil retained through the passage is supplied to the sliding surface, the lubricity is improved and the sliding resistance is reduced.
Thus, both the sealing property of the oil seal 2 and the reduction of the sliding resistance against the rod 3 can be achieved even in a state where the tightening force on the outer peripheral surface of the rod 3 is enhanced to prevent oil leakage in order to improve the oil sealing property. Can do.

  The second embodiment shown in FIG. 3 is also referred to as a dimple on the surface of the rod 3 in place of the oil retaining mechanism of the sliding surface that forms the concavo-convex portions of the grid pattern 11 on the oil seal 2 in the first embodiment. Are provided with a sliding surface oil retaining mechanism that holds required hydraulic oil on the sliding surface between the oil seal 22 and the rod 3 by arranging the minute concave portions 21 in a dot-like manner at equal intervals. .

  Even in such a configuration, as in the first embodiment, the hydraulic oil is supplied to the sliding surface and the oil retaining property that is supplied to the sliding surface at one end provides a more excellent operational effect and improves the supply lubricity. This reduces sliding resistance.

In addition, the third embodiment shown in FIG. 4 employs a configuration in which the uneven portion of the grid pattern 11 is formed in the oil seal 2 of the first embodiment, and the rod 3 shown in the second embodiment is also used. An oil retaining mechanism for the sliding surface is also provided, which employs a configuration in which minute concave portions 21, also called dimples, are arranged in a dot pattern on the surface at regular intervals.
If comprised in this way, the oil retention | holding mechanism of a sliding surface will exhibit the outstanding both effect | action in said 2 embodiment, more superior oil retention property will be obtained, and sliding resistance will reduce.

  In the fourth embodiment shown in FIGS. 5A and 5B, instead of the oil retaining mechanism of the sliding surface in the first embodiment, a slide having a flocking layer 24 provided on the surface including the seal lip 23a of the oil seal 23 is provided. It uses a moving surface oil retaining mechanism.

  Further, the fifth embodiment shown in FIG. 5C has a second seal lip 23b in addition to the configuration in which one seal lip 23a of the oil seal 23 in the fourth embodiment is formed. is there.

  In these embodiments, the working oil that has been in contact with the hair transplantation layer 24 is soaked into the gaps between the fibers and held in the flocking layer 24, and the hydraulic oil that has exuded from the flocking layer 24 is supplied to the sliding surface that is in pressure contact. Lubricated. Accordingly, the tightening force on the outer peripheral surface of the rod 3 is enhanced in order to improve the oil sealability, and the sliding resistance of the oil seal 23 can be reduced even in a state where oil leakage is more reliably prevented.

  The flocking layer 24 in the present invention can be produced using a well-known electrostatic spraying flocking technique or electrostatic flocking technique, and a short fiber having a certain fiber length is formed on the surface of the oil seal including the tip of the seal lip. It is fixed upright through an adhesive layer (not shown) previously applied or by bonding at a certain angle, and finally, short fibers of a predetermined length are implanted at a required density. As is done, the surface is covered in layers.

  Specifically, in electrostatic sprayed flocking, an adhesive is pre-applied to the planned flocking area, and when short fibers are charged and implanted with electrostatic force, not only the electrostatic force but also short fibers are air-filled. By spraying on the adhesive layer with, the short fibers can be fixed at a fixed angle with respect to the substrate surface, and the flocking density is reduced compared to electrostatic flocking, allowing efficient flocking in a short time. .

  In addition, by applying normal electrostatic flocking, an adhesive is preliminarily applied to the area where flocking is planned, and after short fibers are charged and flocked substantially perpendicularly to the adhesive application surface by electrostatic force, a drying step and a finishing step A flocked layer can also be provided by performing etc.

Short fibers used for flocking are not particularly limited as long as they can be used as short fibers for flocking. For example, (1) polyolefin resin such as polyethylene and polypropylene, polyamide resin such as nylon, aromatic polyamide resin, polyethylene terephthalate, polyethylene naphthalate Polyester resin such as phthalate, polyethylene succinate and polybutylene terephthalate, synthetic resin fiber such as acrylic resin, vinyl chloride and vinylon, (2) inorganic fiber such as carbon fiber and glass fiber, (3) regeneration of rayon and acetate Examples include fibers and natural fibers such as cotton, silk, hemp, and wool. These may be used independently and 2 or more types may be used together.
Among these fibers, it is preferable to use synthetic resin fibers because they are hardly chemically swelled or dissolved by oil, are chemically stable, can produce a large amount of homogeneous fibers, and can be obtained at low cost. .

  As a specific form of the short fiber, for example, a length of 0.5 to 2.0 mm and a thickness of 0.5 to 50 dtex are preferable, and the fiber length is not particularly limited, and the form and size of the auto tensioner are not particularly limited. Although a suitable thing can be employ | adopted according to thickness, a thing about 1-10 mm is mentioned, for example, As a density of the short fiber of a flocked part, the ratio for which a fiber occupies per flocked area is 10-30% Is preferred.

Short fibers include straight and bend (shaped with a bent tip), and cross-sectional shapes include circular and polygonal shapes. The bend shape can hold hydraulic oil, grease, and the like more strongly than the straight shape.
By using short fibers with a polygonal cross section, the surface area can be made larger than that of short fibers with a circular cross section, and the surface tension of the lubricant can be increased. It is preferable to select the shape.

  Examples of the adhesive for flocking and fixing the short fibers on the substrate include an adhesive mainly composed of urethane resin, epoxy resin, acrylic resin, vinyl acetate resin, polyimide resin, silicone resin, and the like. For example, urethane resin solvent adhesive, epoxy resin solvent adhesive, vinyl acetate resin solvent adhesive, acrylic resin emulsion adhesive, acrylate-vinyl acetate copolymer emulsion adhesive, vinyl acetate emulsion adhesive , Urethane resin emulsion adhesive, epoxy resin emulsion adhesive, polyester emulsion adhesive, ethylene-vinyl acetate copolymer adhesive and the like. These may be used independently and 2 or more types may be used together.

  In the sixth embodiment shown in FIG. 6, in place of the oil seal 23 in the fourth embodiment, the oil seal 22 of the second embodiment and the second oil seal 25 arranged adjacent to the lower side thereof are provided. The second oil seal 25 is provided with a sliding surface oil retaining mechanism by a thick ring plate-like oil seal 25 formed of a porous material having continuous air holes such as a fiber reinforced resin foam. Is.

  As the porous material, a porous material made of metal, rubber or resin can be employed. As a metal thing, the porous metal etc. which utilized the space material for forming a sintered metal or a cell are mentioned. Examples of the porous material made of rubber or resin include foamable materials using polyolefin, urethane, synthetic rubber, thermoplastic elastomer and the like.

  In the sixth embodiment formed in this way, when the hydraulic auto tensioner mounted on an automobile engine or the like has a possibility that the hydraulic oil hits the oil seal violently and continuously due to shaking or vibration during use, Since the second oil seal 25 made of a porous material gently supplies the operating oil to the sliding surface while reducing the impact force caused by the frequent collision of the operating oil, the first oil seal against the sliding counterpart even in a harsh usage environment. The sliding resistance can be reduced by lowering the pressure contact force of the oil seal 22.

  Further, the seventh embodiment shown in FIG. 7 is an oil seal 26 in which the shape of the second oil seal 25 of the sixth embodiment is changed and a ring-shaped porous material having a U-shaped cross section with an open bottom is used. Further, a flocking layer 24 is provided on the inner peripheral surface.

  When the flocking layer 24 is provided in a predetermined portion of the second oil seal 26 as described above, the oil retaining mechanism is provided on the sliding surface of the second oil seal 26, and the first oil seal 22 disposed adjacently. The sliding oil can be impregnated with a small amount of hydraulic oil by surface tension or the like, and the pressure contact force of the first oil seal 22 can be reduced to reduce the sliding resistance.

  Further, the hydraulic auto tensioner B of the eighth embodiment shown in FIG. 8 is provided with a skirt portion (spring cover) and a cylindrical body 27 integrally with the spring seat 13 that supports the rod 3, and is incorporated in the upper opening of the cylinder. The hydraulic auto tensioner in which the inner peripheral side of the oil seal 23 is elastically brought into contact with the outer periphery of the cylindrical body 27 to form a sealed reservoir chamber 8 between the cylinders 1 and 1 is further used in the oil seal 23 of the fourth embodiment. Is adopted.

  In the eighth embodiment configured as described above, the oil seal 23 with increased pressure contact force is in contact with the sliding surface on the outer periphery of the cylinder 27, and the hydraulic oil is supplied by the flocking layer 24 and the sliding surface is Liquid lubrication is sufficiently performed and sliding resistance is reduced.

  Note that, as in the eighth embodiment shown in FIG. 8, in the hydraulic auto tensioner B provided with the cylindrical skirt portion and the cylindrical body 27 that covers the upper part of the compression spring, the compression spring 10 is covered with the cylindrical body 27. 1 is applied to a use requiring a large spring force because it is accommodated between the skirt portion and the rod 3 and is limited by the size of the compression spring 10.

1 Cylinder 2, 22, 23, 26 Oil seal 2a, 23a, 23b Seal lip 3 Rod 4 Plunger 5 Sleeve 6 Pressure chamber 7 Oil passage 8 Reservoir chamber 9 Check valve 10 Compression spring 11 Grid pattern 12 Flange 13 Spring seat 14 Insert hole 15 Rod positioning member 16 Core metal 17 Garter spring 18 Pulley arm 19 Tension pulley 20 Belt 21 Recess 24 Flocked layer 25 Second oil seal 27 Tubular body 28 Support shaft

Claims (8)

A rod (3) with a plunger (4) is accommodated through an oil seal (2) held in the upper part inside the cylinder (1) in which hydraulic oil and air are accommodated in a cylinder (1) whose upper end is open and whose lower end is closed. ) Is slidably inserted, and a pressure chamber (6) is provided below the plunger (4) that moves up and down while forming a leak gap (L) in the cylinder (1), and this pressure chamber (6) Is provided with a reservoir chamber (8) of hydraulic oil that communicates with the oil-sealed space from the oil passage (7), and the oil passage (7) has a pressure chamber (with a pressure equal to or lower than that of the reservoir chamber (8)). 6) and a check valve (9) for closing the oil passage in a state where the flow of hydraulic oil to the pressure chamber (6) is allowed and the pressure in the pressure chamber (6) is higher than the pressure in the reservoir chamber (8). 4) and cylinder (1) are extended by compression spring (10) In hydraulic auto-tensioner provided with biasing,
A hydraulic auto tensioner provided with one or more oil seals (2) and an oil retaining mechanism for sliding surfaces on the one or more oil seals (2) and / or their sliding counterparts.   The hydraulic auto tensioner according to claim 1, wherein the oil seal (2) is an oil seal (2) made of an elastic material and having one or more seal lips (2a).   The hydraulic auto tensioner according to claim 1 or 2, wherein the sliding partner is a skirt portion provided integrally with a rod (3) or a spring seat (13) that supports the rod (3).   The oil retaining mechanism for the sliding surface is an oil retaining mechanism for the sliding surface based on a linear arrangement or a dot arrangement of minute irregularities provided on the surface of the oil seal (2) or its sliding counterpart or both. Item 4. The hydraulic auto tensioner according to any one of Items 1 to 3.   The oil retaining mechanism for the sliding surface is a sliding surface oil retaining mechanism in which a flock layer (24) is provided on the surface including the seal lip (2a) of the oil seal (2). Hydraulic auto tensioner as described in 1.   The oil retaining mechanism for the sliding surface comprises the oil seal (2) as a first oil seal (2) and a second oil seal (25) disposed adjacently below the first oil seal (2). The hydraulic auto tensioner according to any one of claims 1 to 3, wherein the oil seal (2) is a sliding surface oil retaining mechanism formed as a ring-shaped oil seal formed of a porous material having continuous air holes.   The hydraulic auto tensioner according to claim 6, wherein the second oil seal (25) is an oil seal (26) provided with a flocking layer (24) on an inner peripheral surface.   The hydraulic auto tensioner according to claim 6 or 7, wherein the porous material is a porous material made of metal, rubber or resin.

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