JP5132385B2 - Piston part structure - Google Patents

Description

  The present invention relates to a piston part structure and, for example, relates to an improvement of a piston part structure suitable for realization of a gas spring that assists an opening operation of a rear door in a vehicle.

  Various proposals have heretofore been proposed as a piston part structure suitable for the realization of a gas spring that assists the opening operation of the rear door in the vehicle. Among them, for example, Patent Document 1 discloses an outer periphery of a piston body. A proposal with an O-ring is disclosed.

  That is, in the gas spring disclosed in this document, in the piston portion slidably accommodated in the cylinder body, the piston body defines an extension side chamber and a pressure side chamber in the cylinder body, and an O-ring is provided on the outer periphery. Dressed up.

  At this time, an annular groove is formed on the outer periphery of the piston body, and when the outer periphery of the O-ring arranged in a loosely fitted state in this annular groove is in sliding contact with the inner periphery of the cylinder body, so-called leakage between the two is prevented. doing.

  On the other hand, the O-ring is in the annular groove, and allows the extension side chamber to communicate with the compression side chamber when moving to the compression side chamber side. It functions as a check valve that blocks communication with the side chamber.

  The cylinder body in which the O-ring is in sliding contact has a bypass passage that bypasses the O-ring from the intermediate region to the extended region, and when this bypass passage is utilized, the gas spring expands and contracts without so-called resistance. Is done.

Therefore, in the gas spring disclosed in this document, when the outer periphery of the O-ring is in sliding contact with the inner periphery of the cylinder body that does not have the bypass passage, the O-ring functions as a check valve. When the spring is fully contracted, the rear door of the vehicle can be kept closed as long as the gas spring is not actively extended.
Japanese Patent Laid-Open No. 2001-343043 (refer to Claims 1, paragraphs 0014 and 0021 in the specification, FIGS. 1 and 2)

  However, in the proposal of the above-mentioned literature disclosure, there is basically no problem in that the closed state of the rear door of the vehicle can be maintained when the gas spring is in the most contracted state. It may be pointed out that there is a defect.

  That is, according to the proposal of the above-mentioned literature disclosure, the sealing performance can be ensured when the O-ring is in sliding contact with the cylinder body in the region having no bypass path. For example, the use of the gas spring is stopped for a long time. In such a case, the O-ring may come into close contact with the cylinder body.

  At this time, due to the characteristics of the O-ring, there is no oil film for lubrication between the outer periphery of the O-ring and the inner periphery of the cylinder body. It may worsen the feeling.

  The present invention has been developed in view of the above-described circumstances, and the object of the present invention is to ensure sealing performance and slidability with respect to the cylinder body in the piston portion, for example, versatility in a gas spring. It is to provide a piston part structure that is optimal for expecting improvement.

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. a piston body, the piston structure of the outer periphery is fitted in the annular groove forming the outer circumference of the piston body comprising a piston ring for sliding contact with the inner circumference of the cylinder body, the piston body and one side A damping means is provided that communicates with the other side, and the piston ring is made of a resin-based sliding member and the one end bent inward is deeper than the end of the bottom surface of the annular groove formed on the outer periphery of the piston body. While being fitted in the stop groove, the bottom surface of the annular groove formed on the outer periphery of the piston body is inclined toward the inner circumferential surface in the axial direction of the cylinder body while continuing to the locking groove. In The outer periphery of the other end of the piston ring opposite to the one end of the piston ring is in sliding contact with the inner periphery of the cylinder body while the inner peripheral surface of the main body excluding the one end of the piston ring is in close contact with the inclined bottom surface. Suppose you let it.

  Therefore, in the present invention, since the piston ring is made of a resin-based sliding member, the piston ring is replaced with a urethane ring or the like instead of the O-ring made of urethane or the like in sliding contact with the cylinder body for a long time. Even if it is not used, it is possible to avoid the occurrence of an adhesion phenomenon to the cylinder body.

  In the present invention, the bottom surface of the annular groove formed in the piston body into which the piston ring slidingly contacts the cylinder body is inclined toward the inner circumferential surface in the axial direction of the cylinder body. When the outer periphery of the other end of the piston ring is in sliding contact with the inner periphery of the cylinder body while closely contacting the inner peripheral surface of the main body of the piston ring, the entire circumference of the piston ring is in sliding contact with the inner periphery of the cylinder body. In comparison, the sliding resistance against the cylinder body of the piston portion is ensured and the sealing performance is ensured without unnecessarily increasing the sliding contact resistance.

  Hereinafter, the present invention will be described based on the illustrated embodiment. As shown in FIG. 1, the piston portion structure according to the present invention is a fluid pressure device, for example, slides in a cylinder body 1 in a gas spring. It is embodied in the piston part P of the housing as possible.

  The piston portion P is fitted into a piston body 2 that defines an extension side chamber R1 that is one side inside the cylinder body 1 and a pressure side chamber R2 that is the other side, and an annular groove 21 formed on the outer periphery of the piston body 2. And a piston ring 3 that is slidably brought into sliding contact with the inner periphery of the cylinder body 1.

  The cylinder body 1 constitutes one member in the gas spring, and the rod body 4 that is inserted into the cylinder body 1 so that the tip side can protrude and retract and connects the tip portion to the piston body 2 constitutes the other member. Alternatively, when either one of the rod bodies 4 is connected to the vehicle body side of the vehicle, for example, the other is connected to the rear door side.

  The cylinder body 1 is filled with a gas having a predetermined pressure. From the difference in area between the pressure receiving surface on the pressure side chamber R2 side of the piston body 2 and the pressure receiving surface on the extension side chamber R1 side of the piston body 2, the piston body 2 The gas spring is urged to the extension side in the direction of moving toward the extension side chamber R1.

  The gas spring does not require hydraulic oil in principle, but contains a small amount of oil in order to ensure the lubrication in the so-called sliding portion and the sealing in the seal portion.

  As described above, the piston body 2 defines the inside of the cylinder body 1 into the extension side chamber R1 on the left side in the drawing and the pressure side chamber R2 on the right side in the drawing. , R2 is allowed to pass through the damping means.

  Although not shown, the rod body 4 penetrates the shaft core portion of the sealing member that seals the opening end of the cylinder body 1 under the arrangement of the bearing member and the sealing member, thereby providing a so-called sealing property in the extension side chamber R1. Collateral.

  The piston ring 3 according to the present invention is made of a resin-based sliding member and is formed on the bottom surface of the annular groove 21 formed on the outer periphery of the piston body 2 with one end 3a bent inward which is the right side in the drawing. The engaging groove 22 is formed deeper at the end.

  The piston ring 3 is made of a resin-based sliding member as compared to the case where an O-ring made of urethane or the like is slidably contacted with the cylinder body 1 instead of the piston ring 3 as proposed in the above-mentioned literature disclosure. This is because it is important to avoid the occurrence of the adhesion phenomenon with respect to the cylinder body 1 even if it is not used for a long time.

  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.

  Also, the reason why the one end 3 a of the piston ring 3 is bent inward and is fitted into the annular groove 22 formed on the outer periphery of the piston body 2 is that the piston ring 3 is formed on the outer periphery of the piston body 2. 21 is in the process of being fitted.

  That is, although not shown, the piston ring 3 is roughly divided into two measures for fitting the piston ring 2 in the annular groove 21 on the outer periphery of the piston body 2, and one is a ring base material formed on the annular plate by thermoforming with a die. It is a strategy to do.

  In the case of this measure, a valve stopper 23 (see FIG. 1) formed on an annular plate similar to the ring base material is attached to the rod body 4 after turning so that the heat-formed piston ring 3 does not come off its predetermined position. Fix by caulking on the shaft core.

  The second measure is to press-fit the inner peripheral portion of the ring base material formed on the annular plate into the annular groove 22, and from this state, the ring base material is thermoformed on the outer periphery of the piston body 2 using a die. It is a strategy to do.

  In the case of this measure, the piston ring 3 heat-molded on the outer periphery of the piston body 2 cannot move from the annular groove 21, so that the adjacent valve stopper as described above can be omitted.

  From the above, the one end portion 3a of the piston ring 3 is fitted into the locking groove 22 formed deeper at the end of the bottom surface of the annular groove 21, and therefore the main body portion excluding the one end portion 3a of the piston ring 3 described above. 3b is fixedly fixed in the annular groove 21 so to speak.

  On the other hand, the annular groove 21 formed on the outer periphery of the piston body 2 is in the present invention. As shown in FIG. 2, the inner surface in the axial direction of the cylinder body 1 while the bottom surface continues to the locking groove 22. It is inclined to an ascending slope of an appropriate angle θ toward the surface.

  And the piston ring 3 is the other end which is the left end portion in the figure which is the opposite side of the one end portion 3a of the piston ring 3 while bringing the inner peripheral surface of the main body portion 3b into close contact with the inclined bottom surface of the annular groove 21. The outer periphery of the part 3 c is brought into sliding contact with the inner periphery of the cylinder body 1.

  The bottom surface of the annular groove 21 formed in the piston body 2 is an inclined surface, and the piston ring 3 fitted in the annular groove 21 is slidably contacted with the inner periphery of the cylinder body 1 at the other end portion 3c which is a cut-off end portion. Therefore, compared with the case where the piston ring 3 is slidably contacted with the cylinder body 1 over the entire circumference, the part is linearly slidably contacted with the cylinder body 1, so that both sealing performance and operability are achieved. Security is easy.

  By the way, when the ring base material is heated and softened on the outer periphery of the piston body 2 and pressed into the annular groove 21 while being pressed, the other end portion 3c which is the left end portion in the drawing of the piston ring 3 is not shown, In other words, it is well known that the cylinder body 1 is warped outward as compared with the main body 3b.

  On the other hand, when the outer periphery of the piston ring 3 is set to be in sliding contact with the inner periphery of the cylinder body 1 over the entire circumference, the sliding contact resistance with respect to the cylinder body 1 is increased, and therefore it is not preferable.

  Therefore, in the piston ring 3 whose entire circumference is in sliding contact with the cylinder body 1, the other end portion that warps outward as described above while reducing the so-called interference and reducing the sliding resistance against the cylinder body 1. A measure for ensuring sealing performance by sliding contact with the cylinder body 1 of 3c is well known.

  However, in the other end portion 3c of the piston ring 3 that warps outward, the inner periphery thereof is separated from the bottom surface of the annular groove 21 of the piston body 1, and is in a floating state. Therefore, the other end portion 3c. Is stored in the cylinder body 1, the so-called collapse occurs.

  As a result, the other end 3c of the piston ring 3 warps outward, and there is a concern that the improvement in the sealing performance expected from the other end 3c may not always be as set.

  On the other hand, in the present invention, there is no expectation for outward bending at the end portion 3c of the piston ring 3, and the inner peripheral surface of the piston ring 3, particularly the other end portion 3c. The inner peripheral surface is in close contact with the bottom surface of the annular groove 21.

  Therefore, when the piston ring 3 is accommodated in the cylinder body 1, the other end portion 3 c does not fall down, and therefore, a situation can be revealed in which the outer periphery is reliably in sliding contact with the inner periphery of the cylinder body 1.

  In the present invention, the maximum outer diameter of the other end portion 3c, that is, the cylinder body 1 is obtained in a state where the inner peripheral surface of the other end portion 3c of the piston ring 3 is in close contact with the bottom surface of the annular groove 21. The maximum outer diameter before being housed inside is the same as the inner diameter of the cylinder body 1 or larger than the inner diameter of the cylinder body.

  Even in this case, when the above-described piston ring 3 is fitted into the annular groove 21 in the above-described piston body, the entire circumference of the piston ring 3 is compared with the case where the entire circumference of the piston ring 3 is brought into sliding contact with the inner circumference of the cylinder body 1. Thus, the sliding resistance is not increased unnecessarily, and the sliding property of the piston portion P with respect to the cylinder body 1 can be ensured and the sealing property can be ensured.

  As shown in FIG. 3, at the other end 3 c of the piston ring 3, the cut-out end facing the extension side chamber R <b> 1 in the cylinder body 1 becomes an upward slope toward the inner circumferential surface in the axial direction of the cylinder body 1. And an inclined surface 3d that is inclined at an appropriate angle θ1 with respect to the inner periphery of the cylinder, and a lip A that is slidably in contact with the inner peripheral surface of the cylinder body 1 is formed with the inclined surface 3d. Yes.

  Therefore, in the case of this embodiment, the outer periphery of the other end 3c of the piston ring 3 is in line contact with the inner periphery of the cylinder body 1, and the slidability of the piston ring 3 with respect to the cylinder body 1 is made advantageous. Allows control of sealing properties.

  Incidentally, the inclined surface 3d for forming the lip A can be formed by various measures. Although not shown, the piston ring 3 is thermoformed into the annular groove 21 formed in the piston body 2 and fitted. It is preferably formed on the outer peripheral side portion of the annular plate at the stage of the ring base material before being formed, and at this time, this inclined surface 3d extends over the entire area of the cut-off end as shown by a virtual diagram in the figure. May be formed.

  Although not shown, in particular, the ring base material formed on the annular plate is placed on the outer periphery of the piston body 2 by using a jig by the second measure of fitting the piston ring 3 into the annular groove 21. There is a method of processing the inclined surface 3d together during the heat forming.

  There is also a method of forming the inclined surface 3d by cutting or polishing at a predetermined position in the piston ring 3 fitted in the piston body after the above-described thermoforming is completed.

  FIG. 4 shows an embodiment in which the piston portion structure according to the present invention is embodied in a piston portion P in a hydraulic shock absorber that absorbs road surface vibrations that are input to a wheel that is mounted on a vehicle and is suspended.

  In this embodiment, the locking groove 22 formed in the annular groove 21 in the piston body 2 is positioned at the end of the piston body 2 adjacent to the pressure side chamber R1 in the cylinder body 1, and thus the piston ring. 3, the cut-off end of the piston ring 3 faces the compression side chamber R <b> 2 in the cylinder body 1, contrary to the case of the embodiment shown in FIGS. 1 to 3.

  As a result, the operation on the expansion side is smoother than the operation on the compression side in the hydraulic shock absorber shown in FIG. 4, and therefore, the expansion side damping means provided in the piston portion P can operate smoothly. Become.

  That is, in the embodiment shown in FIGS. 1 to 3, the piston part structure of the present invention has been described as being embodied in the piston part P of the gas spring. However, in the piston part structure according to the present invention, this is the above-described case. Of course, it may be embodied in a hydraulic shock absorber, and in that case, it can be said that the hydraulic shock absorber is preferably set to emphasize the damping action on the extension side.

  In the embodiment shown in FIG. 4, it goes without saying that the inclined surface 3d treatment at the cut-off end shown in FIG. 3 may be performed.

  In the above description, the case where the piston portion structure of the present invention is embodied in the piston portion of the gas spring and the case where the piston portion structure is embodied in a hydraulic shock absorber mounted on a vehicle has been described as an example. However, as long as it is intended, it may be embodied in a hydraulic shock absorber, a hydraulic cylinder, or a pneumatic cylinder as long as the sealing performance is ensured while ensuring the slidability.

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. It is a figure which shows the principal part of the piston part structure by other embodiment similarly to FIG. It is a figure which shows the piston part structure by other embodiment similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder body 2 Piston body 3 Piston ring 3a One end part 3b Main body part 3c Other end part 3d Inclined surface 4 Rod body 21 Annular groove 22 Locking groove A Lip P Piston part R1 One side expansion side chamber R2 The other side pressure side chamber S Gap

Claims (4)

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. In the piston part structure having a piston ring slidably in contact with the inner periphery of the piston , the piston body is provided with damping means for communicating one side and the other side, and the piston ring is made of a resin-based sliding member and is inward The one end bent to the outer periphery of the piston body is fitted into the engaging groove formed deeper at the end of the bottom surface of the annular groove formed on the outer periphery of the piston body, while the bottom surface of the annular groove formed on the outer periphery of the piston body is The cylinder body is inclined toward the inner circumferential surface in the axial direction while continuing to the stop groove, and the inner circumferential surface of the main body portion except the one end portion of the piston ring is in close contact with the inclined bottom surface of the annular groove. Piston unit structure characterized by comprising by sliding contact with the outer periphery of the other end portion on the opposite side of the end portion on the inner periphery of the cylinder body in the piston ring while.   The piston part structure according to claim 1, wherein a maximum outer diameter of the other end part of the piston ring before being accommodated in the cylinder body is the same as or larger than an inner diameter of the cylinder body.   At the other end of the piston ring, the cut-out end facing the cylinder body has an inclined surface inclined toward the inner circumferential surface in the axial direction of the cylinder body, and the inner circumferential surface of the cylinder body is formed by the inclined surface and the outer circumferential surface. The piston part structure according to claim 1 or 2, wherein a lip is formed in sliding contact therewith.   The locking groove is an annular groove formed in the piston body, and is positioned at the end of the piston body adjacent to one side in the cylinder body, or is positioned at the end of the piston body adjacent to the other side of the cylinder body. The piston part structure according to claim 1, claim 2 or claim 3.

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