JP2009228755A - Piston part structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston part structure suitable for guaranteeing sliding performance and sealability against a cylinder body in a piston part, in a hydraulic apparatus such as a hydraulic shock absorber. <P>SOLUTION: This piston part structure has a piston body 2 for defining the inside of the cylinder body 1 into one side and the other side by the piston part P slidably stored in the cylinder body 1, and a piston ring 3 fitted in an annular groove 21 formed on the outer periphery of this piston body 2 and slidingly contacting the outer periphery with the inner periphery of the cylinder body 1, and has an energizing means for energizing the piston ring 3 toward the cylinder body 1 between the piston body 2 sand the piston ring 3 in the piston part P. While forming the piston ring 3 in an endless type while being composed of a rein-based sliding member, the energizing means has a hydraulic pressure introducing part 4 formed on a bottom surface in the annular groove 21 formed in the piston body 2 and introducing hydraulic pressure in the cylinder body 1 while being opposed to the inner periphery of the piston ring 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piston part structure and, for example, relates to an improvement of a piston part structure suitable for implementation in a fluid pressure device such as a hydraulic shock absorber mounted on a vehicle.

  For example, there have been various proposals for a piston portion structure suitable for realization in a fluid pressure device such as a hydraulic shock absorber mounted on a vehicle. Among them, there is a proposal disclosed in Patent Document 1. In the piston portion, the piston ring is urged outward by a backup member disposed behind.

  That is, for example, in a piston portion slidably accommodated in a cylinder body constituting a hydraulic shock absorber, a piston ring is provided on the outer periphery of the piston body to ensure slidability with respect to the cylinder body and to be sealed. Guarantee sex.

  On the other hand, in fluid pressure equipment such as hydraulic shock absorbers, it is well known that slidability and sealability are contradictory properties. Therefore, depending on how to balance the two, the operating performance of the fluid pressure equipment Good or bad is decided.

In view of this, even in the proposals disclosed in the above-mentioned literature, not only the setting for the piston ring is appropriate, but also when the backup member is made of, for example, an O-ring, the elasticity of the O-ring is appropriately set. By being selected, the sealing performance can be ensured while ensuring the sliding performance of the piston portion with respect to the cylinder body.
Japanese Patent Laid-Open No. 2003-130120 (abstract, claim claim 1, paragraphs 0015 to 0017, 0019, and FIG. 1 in the specification)

  However, in the proposal of the above-mentioned literature disclosure, there is basically no problem in ensuring the sealing performance while ensuring the sliding performance with respect to the cylinder body of the piston portion in the fluid pressure device. At that time, it may be pointed out that there is a minor defect.

  That is, there is no problem when the piston ring does not wear and the backup member does not deteriorate in the proposal of the above-mentioned literature disclosure, but the piston ring wears over time and the backup member deteriorates. Is a rule of thumb.

  When the piston ring is actually worn, the sliding gap between the outer periphery of the piston ring and the inner periphery of the cylinder body is directly increased to become a leakage gap, and fluid pressure leakage is expressed.

  Even if the piston ring is not worn, if the backup member deteriorates and, for example, tends to harden, the piston ring cannot slide on the cylinder body as set. The sliding gap between the inner circumference of the cylinder and the inner circumference of the cylinder increases and fluid pressure leaks.

  In addition, in consideration of the above-described piston ring wear and deterioration of the backup member, for example, when the thickness of the piston ring is increased in advance and the elasticity of the backup member is increased in advance, the sealing performance is guaranteed. While it is advantageous for preventing fluid pressure leakage, it causes a problem that the slidability is lowered.

  The present invention was devised in view of the above-described circumstances, and its object is to ensure slidability and sealing performance of the piston portion with respect to the cylinder body. For example, a fluid pressure device such as a hydraulic shock absorber is provided. It is providing the piston part structure which is optimal for expecting the improvement of versatility.

  In order to achieve the above-described object, the structure of the piston portion structure according to the present invention is basically configured such that the piston portion slidably accommodated in the cylinder body defines the cylinder body on one side and the other side. And a piston ring that is fitted into an annular groove formed on the outer periphery of the piston body so that the outer periphery slides on the inner periphery of the cylinder body, and between the piston body and the piston ring in the piston portion. In the piston part structure having an urging means for urging the piston ring toward the cylinder body, the piston ring is made of an endless type made of a resin-based sliding member, while the urging means is applied to the piston body. It is assumed that a fluid pressure introducing portion is formed on the bottom surface of the formed annular groove and introduces fluid pressure in the cylinder body while facing the inner periphery of the piston ring.

  Therefore, in the present invention, the biasing means is formed on the bottom surface of the annular groove formed in the piston body for fitting the piston ring, and the fluid pressure in the cylinder body is applied while facing the inner periphery of the piston ring. Since the fluid pressure introducing portion is introduced, when the fluid pressure is introduced into the fluid pressure introducing portion, the part of the piston ring facing the fluid pressure introducing portion is directed outward by the fluid pressure, that is, toward the cylinder body. Protruding.

  As a result, the contact surface pressure of the piston ring against the cylinder body is improved. Therefore, even if the piston ring wears out over a long period of time, the sealing performance is ensured while ensuring the predetermined slidability. To do.

  And since the urging means is formed in an annular groove into which the piston ring is fitted and is a fluid pressure introducing portion facing the inner periphery of the piston ring, compared with the case where the urging means has a backup member, for example, The slidability and sealing performance of the piston portion with respect to the cylinder body can be ensured without fearing the adverse effects caused by the deterioration of the backup member.

  Hereinafter, the present invention will be described based on the illustrated embodiment. The piston structure according to the present invention is slidable in a cylinder body 1 in a hydraulic shock absorber, for example, as a fluid pressure device. It is embodied in the piston part P of the storage.

  The piston portion P is fitted into a piston body 2 that defines the inside of the cylinder body 1 on one side and the other side, and an annular groove 21 formed on the outer periphery of the piston body 2, and the outer periphery of the piston part P And a piston ring 3 that is slidably contacted with the inner periphery.

  Further, the piston part structure according to the present invention has an urging means for urging the piston ring 3 toward the outer cylinder body 1 between the piston body 2 and the piston ring 3 in the piston part P. The urging means has a fluid pressure introducing portion 4 that is formed on the bottom surface of the annular groove 21 formed in the piston body 2 and introduces the fluid pressure in the cylinder body 1 while facing the inner periphery of the piston ring 3. It becomes.

  When the hydraulic shock absorber is a double cylinder type, the cylinder body 1 is an inner cylinder that is concentrically arranged in an outer cylinder (not shown), and the cylinder body 1 is located between the cylinder body 1 and the outer cylinder. 1 is set to a reservoir (chamber) communicating with the inside.

  When the cylinder body 1 constitutes a single cylinder type hydraulic shock absorber, in many cases, a free piston (not shown) in series with the piston portion P is slidably accommodated in the cylinder body 1. An air spring chamber (not shown) is defined behind the free piston.

  The piston body 2 defines the inside of the cylinder body 1 into an oil chamber R1 on one side on the right side in the drawing and an oil chamber R2 on the other side on the left side in the drawing, while these two oil chambers R1. , R2 is allowed to pass through a damping means (not shown).

  The piston body 2 is connected to a piston rod 5 as shown in the figure. The piston rod 5 is an upper member when the cylinder body 1 is a lower member, for example.

  In addition, although not shown in figure, the piston rod 5 penetrates the axial center part of the sealing member which seals the opening end of the cylinder body 1 under arrangement | positioning of a bearing member and a sealing member, and oil chamber R1 which is said one side The so-called hermeticity is secured.

  By the way, the annular groove 21 formed on the outer periphery of the piston body 2 is a land portion that is an end portion in the axial direction that is the moving direction of the piston body 2, that is, one land portion that is one end portion facing the oil chamber R2. 22 and the other land portion 23 that is the other end facing the oil chamber R1 are defined to have a depth that allows the piston ring 3 to be fitted to a predetermined depth.

  In the present invention, the piston ring 3 fitted in the annular groove 21 is an endless type made of a resin-based sliding member. Although not shown, the ring base material formed in a cylindrical shape is cured. Under the use of the tool, it is inserted into the annular groove 21 on the outer periphery of the piston body 2, and from this state, the diameter is reduced and shaped into a predetermined fitting state by using the jig.

  The piston ring 3 made of a resin-based sliding member is a preferable choice because the piston ring 3 is formed in an endless type.

  That is, in the present invention, the urging means has the fluid pressure introducing portion 4 for introducing the fluid pressure in the cylinder body 1, and therefore the fluid pressure introduced into the fluid pressure introducing portion 4 is effectively utilized. For this, the piston ring 3 is preferably formed in an endless type.

  For fitting the piston ring 3 formed in this endless type into the annular groove 21 formed on the outer periphery of the piston body 2, as described above, the ring base material formed in a cylindrical shape is used under the jig. Therefore, it is preferable to use a resin material that can be easily shaped.

  In addition, as a resin material which comprises the resin-type sliding member which is the piston ring 3, as a synthetic resin material, for example, polyethylene (PE), polyacetal (POM), polyamide (PA), polyetheretherketone (PEEK), polyimide ( In addition to PTFE, PFA, FEP, ETFE, and PVDF are included as fluorine resin materials.

  The piston ring 3 formed as described above has a portion where the hydraulic pressure acts on the outer side as indicated by a symbol A in FIG. 2 due to the hydraulic pressure as the fluid pressure introduced into the fluid pressure introducing portion 4 as the urging means. The outer circumference that protrudes toward the cylinder body 1 and expands is in sliding contact with the inner circumference of the cylinder body 1.

  That is, as described above, the fluid pressure introducing portion 4 is formed on the bottom surface of the annular groove 21 formed in the piston body 2 and introduces the hydraulic pressure in the cylinder body 1 while facing the inner periphery of the piston ring 3. In the figure, the cylinder body 1 is positioned closer to the end surface facing the oil chamber R1 on one side.

  Therefore, when the oil chamber R1 is at a higher pressure than the oil chamber R2, the oil pressure from the oil chamber R1 in the cylinder body 1 is introduced into the fluid pressure introducing portion 4, and this oil pressure acts by this oil pressure. The part is protruded toward the cylinder body 1 which is the outer side.

  At this time, the piston ring 3 tends to be in sliding contact with the inner periphery of the cylinder body 1 as indicated by the symbol A in FIG. Is improved.

  As a result, the contact surface pressure of the piston ring 3 with respect to the cylinder body 1 is improved. Therefore, even if the piston ring 3 is worn over a long period of use, the seal is secured while ensuring a predetermined slidability. Ensure sex.

  Since the urging means is formed in the annular groove 21 into which the piston ring 3 is fitted and is the fluid pressure introducing portion 4 facing the inner periphery of the piston ring 3, the urging means is disclosed as disclosed in the above literature. As compared with the case where the backup member is provided, for example, the slidability and the sealing performance of the piston portion P with respect to the cylinder body 1 can be ensured without fear of adverse effects due to deterioration of the backup member.

  In view of the above, the fluid pressure introduction unit 4 is required to introduce the hydraulic pressure, so that the introduction of the hydraulic pressure to the fluid pressure introduction unit 4 is facilitated as shown by the phantom diagram in FIG. A guide path 24 is preferably formed.

  That is, as shown in the figure, in the piston body 2, the other land portion 23 in the piston body 2 that forms the annular groove 21 into which the piston ring 3 is fitted promotes the introduction of hydraulic pressure into the fluid pressure introduction section 4. A guide path 24 is provided.

  The guide path 24 has one end communicating with the oil chamber R1 in the cylinder body 1 and the other end opposed to the end face of the piston ring 3 in the figure, but instead, for example, As shown in FIG. 3, the fluid pressure introducing unit 4 may be communicated.

  In this way, when the guide path 24 is formed, the introduction of the hydraulic pressure into the fluid pressure introducing portion 4 is promoted. In other words, the portion of the piston ring 3 facing the fluid pressure introducing portion 4 is the fluid. This prevents the occurrence of the phenomenon of falling or bending into the pressure introduction part 4, and produces an advantage that the diameter of the piston ring 3 facing the fluid pressure introduction part 4 can be secured outward.

  As described above, any shape or size of the guide path 24 is arbitrary as long as it facilitates the introduction of the hydraulic pressure to the fluid pressure introducing portion 4 as a result.

  Incidentally, for example, as shown in FIG. 3, for example, the shape is a semicircle (24a) or a semi-oval (24b), or a U-shape (24c) or a circle (24d). It would be advantageous from the top.

  In addition, since the opening is a circular hole in the guide path 24d described above, for example, the same as the “communication path 2b” disclosed in FIG. 7 of JP-A-58-68546. obtain.

  However, the “communication passage 2b” disclosed in this publication communicates with the “ring groove 3” that accommodates the “O-ring 1”, and the fluid pressure introduction located behind the piston ring 3 as in the present invention. Therefore, the guide path 24d is a proposal not disclosed in the above publication.

  On the other hand, as long as the fluid pressure introducing portion 4 acts to oppose the inner periphery of the piston ring 3 to improve the sealing performance with the cylinder body 1 as a result, the fluid pressure introducing portion 4 is not arranged. Is optional.

  That is, in the above description, since the oil chamber R1 facing the other land portion 23 is on the high pressure side as an example, the fluid pressure introducing portion 4 is positioned closer to the end surface facing the oil chamber R1. However, when the oil chamber R2 facing one of the land portions 22 is on the high pressure side, as shown in FIG. 4A, the oil chamber R2 is positioned closer to the end surface facing the oil chamber R2. preferable.

  When both the oil chambers R1, R2 repeat the high pressure side and the low pressure side, as shown in FIG. 4B, the piston body 2 near the end surface facing the oil chamber R2 in the cylinder body 1 and It is preferable that each is positioned closer to the end face facing the oil chamber R2.

  When the fluid pressure introducing portion 4 is positioned near the end surface facing the oil chamber R2 and a guiding path is provided, the guiding path is formed in one land portion 22 (not shown). Of course.

  The fluid pressure introducing portion 4 is formed in an annular shape that is formed in the piston body 1 and deepens a part of the bottom surface of the annular groove 21 into which the piston ring 3 is fitted.

  From this, the cross-sectional shape of the fluid pressure introducing portion 4 formed in an annular shape is basically arbitrary. For example, the triangle shown in FIG. 5A and the rectangle shown in FIG. In the case of either a semicircular shape or a semielliptical shape shown in FIG. 5C, the formation becomes easy, which is advantageous in expecting improvement in versatility of the present invention.

  In the above description, the piston portion structure of the present invention has been described as being embodied in the piston portion of a hydraulic shock absorber as a fluid pressure device. However, from the point of view of the present invention, while ensuring the slidability, As long as the sealing performance is ensured, it may be embodied in a piston portion in a hydraulic cylinder or pneumatic equipment.

It is a partial semi-sectional view showing a piston part structure according to an embodiment of the present invention. It is a fragmentary sectional view which expands and shows the principal part of the piston part structure of FIG. FIG. 3 is a partial side view showing an embodiment of a taxiway as seen from a YY line position in FIG. 2. It is a fragmentary figure which shows embodiment of the arrangement | positioning state of a fluid pressure introduction part. It is a fragmentary figure which shows embodiment of the cross-sectional shape of a fluid pressure introduction part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder body 2 Piston body 3 Piston ring 4 Fluid pressure introduction part 5 Piston rod 21 Annular groove 23 Land part 24 (24a, 24b, 24c, 24d) Guide way P Piston part R1 Oil chamber which is one side R2 Oil chamber which is the other side

Claims (6)

A piston part slidably accommodated in the cylinder body is defined in one side and the other side in the cylinder body, and is fitted in an annular groove formed on the outer periphery of the piston body. And a piston part structure having a biasing means for biasing the piston ring toward the cylinder body between the piston body and the piston ring in the piston part. While the piston ring is made of a resin-based sliding member and is endless, the urging means is formed on the bottom surface of the annular groove formed in the piston body and faces the inner periphery of the piston ring while fluid pressure in the cylinder body. A piston part structure characterized by having a fluid pressure introduction part that introduces. The fluid pressure introducing portion is positioned near the end surface facing the one side in the cylinder body in the piston body, or positioned near the end surface facing the other side in the cylinder body in the piston body, or one of the piston bodies in the cylinder body in the piston body The piston part structure according to claim 1, wherein the piston part structure is positioned near an end face facing the side and near an end face facing the other side. The piston part structure according to claim 1 or 2, wherein the fluid pressure introducing part is formed in an annular shape in which a part of the bottom surface of the annular groove into which the piston ring is fitted is formed deeper in the piston body. The piston part structure according to claim 3, wherein a cross-sectional shape of the annularly formed fluid pressure introducing part is any one of a rectangle, a triangle, a semicircle, and a semi-oval. The land portion of the piston body forming the annular groove into which the piston ring is fitted has a guide path for promoting introduction of fluid pressure into the fluid pressure introduction portion. Item 5. The piston part structure according to Item 4. 6. The piston part structure according to claim 5, wherein the guide path has one end communicating with the cylinder body and the other end facing the end face of the piston ring or communicating with the fluid pressure introducing part.

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