JP2529107Y2 - Cylinder seal structure - Google Patents

Description

[Detailed description of the invention] "Industrial application field" The present invention relates to a sheath structure having a high sealing property and a low friction property, for example, to improve the riding comfort of a car and the stability of driving. The present invention relates to a seal structure of a hydraulic cylinder used for a suspension hydraulic shock absorber or the like.

"Prior art" As a conventional seal structure of this kind, there is one as shown in FIGS. FIG. 5 shows an outline of a hydraulic cylinder used for a suspension hydraulic shock absorber. The hydraulic cylinder comprises an inner cylinder 1 and an outer cylinder 2.
A piston rod 4 is attached to a piston 3 slidably provided in an inner cylinder 1 of a double cylinder comprising
The piston rod 4 is configured to penetrate a rod guide 6, a plate 6b and a rod ring 7 having a rod seal 5 provided on the upper portion of the inner and outer cylinders, and protrude from the upper portion of the outer cylinder 2 to the outside.

The piston rod 4 is provided with a through hole 4a, through which pressure oil is supplied to and discharged from the oil chamber in the inner cylinder 1 through the through hole 4a. Also, this through hole 4a
Is connected to an accumulator (not shown) filled with high-pressure gas through a damping force generation valve (not shown).
The vibration acting between the piston rod 4 and the inner and outer cylinders 1 and 2 is damped. The space between the inner cylinder 1 and the outer cylinder 2 is a reservoir for storing a small amount of oil leaking from between the piston rod 4 and the rod seal 5.

FIG. 6 is an enlarged view of the vicinity of the rod guide 6. A ring-shaped groove 6 a formed on the inner peripheral surface of the rod guide 6 and the plate 6 b has an annular shape mounted on the outer periphery of the piston rod 4. A rod seal 5 formed and made of a tetrafluoroethylene resin or the like is provided, and a rubber O-ring 8 whose outer peripheral surface is in close contact with the wall surface of the groove 6a is fitted to the outer peripheral surface of the rod seal 5. ing.

In addition, an annular step is formed on the inner peripheral surface of the rod seal 5.
5a and a tapered surface 5b are formed.
A sharp edge 5c is provided between 5b and 5b. The interference between the O-ring 8 and the rod seal 5 and the interference of the rod seal 5 cooperate with each other so that the O-ring 8 comes into close contact with the piston rod 4.
Since it is only 5c, the sharp edge 5c shows an extremely large contact surface pressure distribution, and is thereby configured to exhibit excellent sealing performance with respect to the fluid on the high pressure side Pi.

[Problem to be Solved by the Invention] However, in the above-described conventional hydraulic cylinder seal structure, the close contact surface of the rod seal 5 is only the sharp edge 5c. When a large pressure is applied from, as shown in FIG.
The rod seal 5 and the O-ring 8 are pressed against the plate 6b which is the low pressure side (atmosphere side) Po wall surface of the groove 6a,
The low-pressure side portion of the rod seal 5 is inclined so as to approach the piston rod 4 side with the sharp edge 5c as a fulcrum, and substantially the entire tapered surface 5b of the rod seal 5 is
, The contact surface pressure p is dispersed, and the sealing performance is significantly reduced.

Conversely, as shown in FIG. 8, the pressing center G of the O-ring is higher than the sharp edge 5c of the rod seal 5 on the high pressure side Pi.
When the rod is deviated by 1 dimension, the component of the pressure applied to the O-ring acts as a moment with the sharp edge 5c as a fulcrum, and as shown in FIG. There is a problem that the portion 5a is pushed and bent so as to approach the piston rod 4 side, thereby reducing the sealing performance and reducing the durability of the rod seal.

The present invention has been made in view of the above problems, and can enhance the sealing function of the rod seal, reduce friction of the seal, and improve the riding comfort of the vehicle, and the like. It is an object of the present invention to provide a cylinder seal structure capable of preventing a rod seal from tilting due to dragging of a piston rod, pressure fluctuation, or the like.

Means for Solving the Problems In the present invention, a piston rod is provided movably in the axial direction inside a cylinder, a rod seal is fitted around the outer periphery of the piston rod, and provided on the outer periphery of the rod seal. A cylindrical seal structure for pressing the rod seal radially inward of the piston rod by a pressing ring having elasticity, wherein the inner surface of the rod seal is annular and the piston rod has Forming a sharp edge that is in close contact with the outer peripheral surface, and further providing a rigid annular member at a predetermined position of the rod seal so as to prevent deformation in a direction approaching the piston rod with the sharp edge as a fulcrum; The member presses the pressing ring from the sharp edge in a direction parallel to the axis of the piston rod. Is located at a position shifted toward the side where the center of action acts.

[Operation] In the cylinder seal structure of the present invention configured as described above, if a rigid annular member is disposed on the low pressure side of the rod seal, one of the pressing rings can be arranged from the high pressure side of the cylinder. Even if pressure is applied to the side surface and the low pressure side portion of the rod seal is pressed toward the piston rod side with the sharp edge as a fulcrum, the rod member is not inclined and deformed by the annular member. Also, if a rigid annular member is arranged on the high pressure side of the rod seal, the pressing center of the pressing ring deviates from the sharp edge to the high pressure side, and the component force of the pressure applied to the pressing ring reduces the sharp edge. It acts on the high pressure side as a moment acting as a fulcrum, and even if it tries to push and bend the high pressure side portion of the rod seal toward the piston rod side, it is prevented by the annular member. In addition, since the annular member is provided at a position shifted to the side on which the pressing force of the pressing ring acts, even when the sharp edge is worn, the pressing force can be directly applied to the rod seal.

Hereinafter, the present invention will be described with reference to the drawings. FIGS. 1 to 4 show an embodiment of the cylinder seal structure of the present invention, which is an enlarged cross section of a part of the seal portion of the hydraulic shock absorber shown in FIG. In these drawings, the same components as those of the conventional technique are denoted by the same reference numerals, and description thereof is omitted.

FIG. 1 shows a first embodiment of the seal structure of the present invention. The seal structure is formed on an inner peripheral surface of a rod guide 6 and a plate 6b disposed on an outer peripheral surface of a piston rod 4. A rod seal 5 made of a tetrafluoroethylene resin material, which is disposed inside the annular groove 6 a and is in close contact with the outer periphery of the piston rod 4, and a rubber or the like which applies a close contact pressure to the rod seal 5 It is composed of a pressing ring formed of an elastic material, for example, a combination with an O-ring 8.

The rod seal 5 is formed in a cylindrical shape, and an annular step 5a and an annular tapered surface 5b are formed on the inner peripheral surface of the rod seal 5, and the step 5a and the tapered surface are formed. A sharp edge 5c that is in close contact with the outer peripheral surface of the piston rod 4 is formed between the sharp edge 5c and the outer edge 5c. In the case of this embodiment, the pressing center G of the O-ring is deviated by 1 dimension from the sharp edge 5c to the low pressure side Po side, and at the low pressure side Po end of the outer peripheral surface of the rod seal 5, A rigid metal annular member 11 having a predetermined thickness and length dimension
Are fitted.

Therefore, in the seal structure of this embodiment, the component force of the pressing force applied from the high pressure side Pi of the cylinder to the O-ring 8 acts on the low pressure side Po portion of the rod seal 5 as a moment about the sharp edge 5c as a fulcrum. However, since the metal annular member 11 is fitted on the outer peripheral surface of the low pressure side Po end of the rod seal 5, the tapered surface 5b of the rod seal 5 is inclined so as to approach the piston rod 4 side. Without deformation, only the sharp edge always comes in close contact with the piston rod 4, so that the sealing function of the rod seal 5 can be enhanced, and the friction of the rod seal 5 can be kept low, so that the rider can ride the vehicle. Comfort can be improved. Further, the life of the rod seal can be extended without the seal ring being tilted due to dragging of the piston rod, pressure fluctuation, or the like.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the pressing center G of the O-ring of the first embodiment is deviated toward the high pressure side from the sharp edge 5c, and the end of the high pressure side Po of the rod seal 5 (step portion 5a). A rigid metal annular member 11 formed to have a predetermined length and thickness dimension is fitted on the peripheral surface side.

Therefore, in the seal structure of the present embodiment, the component force of the pressing force applied to the O-ring 8 from the high pressure side Pi of the cylinder is applied to the high pressure side Pi end of the rod seal 5 as a moment about the sharp edge 5c as a fulcrum. Even if it acts, the metal annular member 11 is fitted on the inner peripheral surface side of the high pressure side Pi end of the rod seal 5 so that the step 5a of the rod seal 5 approaches the piston rod 4 side. It does not tilt or deform, and has the same operation and effect as the first embodiment.

3 and 4 show a third and a fourth embodiment of the present invention. FIG. 3 shows the annular member 11 of the second embodiment.
Is fitted to the outer peripheral surface of the high pressure side Pi end of the rod seal 5. FIG. 4 shows the annular member 11 of the second embodiment embedded in the high pressure side Pi end of the rod seal 5. Things. Therefore, the third and fourth embodiments also have the same operation and effect as the second embodiment.

In the above-described embodiment, a metal ring is used for the annular member. However, the present invention is not limited to this, and a predetermined rigidity may be used to prevent deformation of the rod seal against a moment acting on the O-ring. What is necessary is just to have. Further, the arrangement position of the annular member 11, and the outer diameter size, etc.
It is needless to say that the design can be appropriately changed without being limited to the above-described example. Further, the annular member 11 may be provided on both the high pressure side and the low pressure side of the rod seal.

"Effect of the invention" As described above, the seal structure of the cylinder of the invention is
On the inner peripheral surface of a rod seal having a pressing ring attached to the outer periphery, a sharp edge is formed in close contact with the outer peripheral surface of the piston rod, and a rigid annular member is disposed at a predetermined position of the rod seal. Therefore, even if high pressure acts on one side of the pressing ring from the high pressure side of the cylinder to deform the rod seal, the rod seal is prevented from being deformed by the rigid annular member. The seal function can be improved, and the friction of the seal can be reduced to improve the riding comfort of the car, and the rod seal can be prevented from tilting due to dragging of the piston rod or pressure fluctuation. it can. Further, since the annular member is provided at a position shifted to the side where the pressing force of the pressing ring acts, even if the sharp edge is worn, the pressing force is directly applied to the rod seal to apply the sharp edge to the outer periphery of the piston rod. To maintain the sealing property.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a part of a seal structure showing a first embodiment of a cylinder seal structure of the present invention, FIG.
FIG. 4 shows a second embodiment of the present invention and is an enlarged sectional view of a part of a seal structure. FIG. 3 shows a third embodiment of the present invention and is an enlarged sectional view of a part of the seal structure. FIG. 4 shows a fourth embodiment of the present invention, in which an enlarged sectional view of a part of a seal structure. FIGS. 5 to 9 show a conventional technique, and FIG. 6 and 7 are enlarged sectional views of a part of a seal structure, and FIGS. 8 and 9 are enlarged sectional views of a part of another seal structure. 1 ... inner cylinder, 2 ... outer cylinder, 4 ... piston rod, 5 ... rod seal, 5a ... step, 5b ... taper, 5c ... sharp edge, 6 ... rod guide, 8
... O-ring (pressing ring), 11 ... annular member.

Claims (1)

(57) [Scope of request for utility model registration] A piston rod is provided inside the cylinder so as to be movable in the axial direction, a rod seal is fitted on the outer periphery of the piston rod, and an elastic pressing ring provided on the outer periphery of the rod seal serves as the piston rod. A seal structure in which a rod seal is pressed inward in the radial direction of the piston rod, wherein a sharp edge is formed on an inner peripheral surface of the rod seal and is in close contact with an outer peripheral surface of the piston rod. Further, an annular member having rigidity is disposed at a predetermined position of the rod seal so as to prevent deformation in a direction approaching the piston rod with a sharp edge as a fulcrum, and the annular member is provided with the piston from the sharp edge. Along the direction parallel to the axis of the rod, it is located at a position shifted toward the side where the center of the pressing force of the pressing ring acts. Seal structure of a cylinder, characterized in that it is.