JPH074462A - Cylinder device - Google Patents

Abstract

PURPOSE:To improve the service life and the durability of a rod seal by preventing the protruding of the rod seal between a piston rod and a rod guide. CONSTITUTION:In the recess 21D of a rod guide 21, a guide ring 24 movable in the diameter direction is provided, and a rod seal 22 and an O-ring 23 are held in the recess 21D of the rod guide 21 by the guide ring 24. And, even though a piston rod 8 is position-slipped in the diameter direction inside a rod through hole 21C, the guide ring 24 becomes to regulate the center automatically to the piston rod 8, and the formation of a large clearance to protrude the rod seal 22 between the piston rod 8 and the inner peripheral surface of the guide ring 24 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device suitable for use in, for example, a suspension device for vehicles.

[0002]

2. Description of the Related Art FIGS. 3 to 5 show a suspension device for a vehicle as an example of a conventional cylinder device.

In the drawing, 1 is an outer cylinder, 2 is an inner cylinder as a tube coaxially arranged in the outer cylinder 1, and the lower ends of the inner cylinder 2 and the outer cylinder 1 are closed by a bottom cap 3. Is
On the lower end side of the bottom cap 3, a mounting eye 4 for mounting the outer cylinder 1 on the axle side (not shown) of the vehicle is integrally formed.

Reference numeral 5 denotes a stepped cylindrical rod guide provided on the upper end side of the inner cylinder 2. The rod guide 5 has a large diameter portion 5A whose outer peripheral surface is fitted to the inner peripheral surface of the outer cylinder 1. Outer peripheral surface is inner cylinder 2
The rod guide 5 has a rod insertion hole 5C into which a piston rod 8 described later is inserted. Further, an annular ring groove 5D is formed on the inner peripheral side of the rod guide 5 so as to communicate with the rod insertion hole 5C, and a rod seal 13 and the like described later are mounted in the ring groove 5D.

Reference numeral 6 denotes a guide cylinder provided on the inner periphery of the lower side of the rod guide 5. The guide cylinder 6 is made of a resin material having high wear resistance and formed into a cylinder shape. And is slidably supported.

Reference numeral 7 denotes a piston which is located inside the inner cylinder 2 and is slidably inserted in the axial direction so as to define the inside of the inner cylinder 2 into two oil chambers A and B. A plurality of oil holes 7A, 7A are provided to communicate between the oil chambers A, B, and the pressure oil is circulated between the oil chambers A, B through the oil holes 7A.

The lower end 8 of the inner cylinder 2 is fixed to the piston 7, and the upper end of the inner cylinder 2 is inserted through the rod insertion hole 5C of the rod guide 5.
Of the piston rod 8, an oil passage 8A penetrating in the axial direction is bored in the piston rod 8, and an oil hole 8B communicating with the oil passage 8A is formed on the protruding end side of the piston rod 8. It is provided in the radial direction. The projecting end side of the piston rod 8 is attached to the vehicle body side (not shown) of the vehicle, and the piston rod 8 is configured to expand and contract in the axial direction from the outer cylinder 1 and the inner cylinder 2 by the vibration of the vehicle. There is.

Reference numeral 9 denotes an upper cap provided on the upper end side of the outer cylinder 1, and the upper cap 9 is fitted and fixed to the inner circumference of the upper end side of the outer cylinder 1 to cover the upper end side of the outer cylinder 1. ing.

Reference numeral 10 denotes a dust seal provided in the upper cap 9. The dust seal 10 is made of an elastic material and is formed into a short cylindrical shape. The inner peripheral surface of the dust seal 10 is in sliding contact with the piston rod 8 and the piston rod 8 and the rod guide. The pressure oil leaking from the oil chamber A in the inner cylinder 2 through the gap 5 is sealed so as not to leak to the outside of the outer cylinder 1, and water, dust, etc. from the outside of the outer cylinder 1 enter the outer cylinder 1. Prevents infiltration.

Reference numeral 11 denotes an accumulator, and the accumulator 11 is provided with an oil chamber 11B and a gas chamber 11C by means of a free piston 11A as a defining member provided therein.
The oil chamber 11B is connected to the oil hole 8B of the piston rod 8 through the pipe 12.

Reference numeral 13 denotes a rod seal fitted in the ring groove 5D of the rod guide 5, and the rod seal 13 is formed in an annular shape from an elastic resin material such as polytetrafluoroethylene. And the rod seal 1
As shown in FIG. 4, an O-ring 14 described later makes sliding contact with the outer peripheral surface of the piston rod 8 with a relatively large interference, and the pressure oil in the oil chamber A causes a gap between the piston rod 8 and the rod guide 5. It is prevented from leaking to the outside through.

Reference numeral 14 denotes an O-ring arranged on the outer peripheral side of the rod seal 13. The O-ring 14 is formed in an annular shape by an elastic resin material, and the rod seal 13 is elastic toward the outer peripheral surface of the piston rod 8. The pressure oil is prevented from flowing through the outside of the rod seal 13 while being urged to. The O-ring 14 is the rod seal 13
Together with this, it constitutes a seal member.

Further, reference numerals 15 and 16 denote extension-side and contraction-side damping force generating mechanisms provided on the piston 7, and the damping force generating mechanisms 15 and 16 respectively exert predetermined damping forces when the piston rod 8 is extended and contracted. generate.

The suspension device according to the prior art has the above-mentioned structure. When vibration occurs during traveling of the vehicle, the piston rod 8 expands and contracts from the outer cylinder 1 and the oil chambers A and B in the inner cylinder 2 are extended. The pressure oil is circulated through the oil holes 7A of the piston 7 in order to reduce the damping force generation mechanism 15, 1
At 6, a predetermined damping force is generated to dampen the vibration of the vehicle.

[0015]

By the way, in the above-mentioned prior art, the damping force generating mechanism 1 is provided for the vertical vibration generated when the vehicle is running, due to the expansion and contraction of the piston rod 8.
It absorbs at 5,16. However, the vibration of the vehicle not only acts in the vertical direction, which is the direction of expansion and contraction of the piston rod 8, but also is perpendicular to the direction of expansion and contraction of the piston rod 8 due to, for example, inertial force generated when the vehicle turns, tire reaction force, and the like. It also acts laterally, which is the direction. Then, the vibration or load in the lateral direction causes the piston rod 8 to incline with respect to the axes of the outer cylinder 1 and the inner cylinder 2, and deteriorates the slidability of the piston rod 8.

Therefore, in the prior art, the piston rod 8
A gap is formed between the rod guide 5 and the rod guide 5 at a predetermined distance to allow the piston rod 8 to be displaced in the radial direction within the rod insertion hole 5C of the rod guide 5, and the piston rod 8 is prevented from moving to the outer cylinder 1 and the inside. Even if the cylinder 2 is slightly inclined with respect to the axial direction, the slidability of the piston rod 8 is prevented from being deteriorated.

However, in the prior art, the piston rod 8
Is displaced radially in the rod insertion hole 5C of the rod guide 5, the piston rod 8 and the rod guide 5
The gaps between and become uneven in the circumferential direction, and the gaps are partially increased. In this state, for example, when a frictional force or the like acts on the rod seal 13 from the piston rod 8 when the piston rod 8 extends, the rod seal 13 causes the piston rod 8 and the rod guide 5 to move. It enters the large gap formed between the gaps and becomes the protruding portion 13A as shown in FIG.

Further, when the piston rod 8 is repeatedly expanded and contracted in a state where the rod seal 13 is deformed as shown in FIG. 5, the rod seal 13 is worn and damaged by sliding friction with the piston rod 8 and durability is improved. There is a problem of a significant decrease.

On the other hand, if the inner diameter of the rod guide 5 is reduced and the clearance between the piston rod 8 and the rod guide 5 is reduced, the rod seal 13 is prevented from being deformed as shown in FIG. Is possible. But,
In this case, when the piston rod 8 is displaced in the radial direction within the rod insertion hole 5C of the rod guide 5 due to the lateral vibration or load, the piston rod 8 tilts toward the inner peripheral surface of the rod guide 5. However, there is a problem in that the outer peripheral surface of the piston rod 8 is damaged when the piston rod 8 interferes with each other.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention is such that the rod seal may be deformed when a lateral vibration or load acts between the piston rod and the rod guide. It is an object of the present invention to provide a cylinder device capable of preventing the piston rod from being damaged and improving durability.

[0021]

In order to solve the above-mentioned problems, the feature of the structure adopted by the present invention is that the rod guide is formed in a U-shaped cross-section by opening on the inner peripheral surface of the rod guide. And an annular guide ring that is provided in the recess and that moves radially between the rod guide and the piston rod, and the guide ring is located on the outer peripheral side of the seal member. And a cylindrical portion for holding the seal member between the piston rod and the cylindrical member at a position opposite to the oil chamber side with respect to the seal member so as to project radially inward from the cylindrical portion. The inner diameter of the inner flange is formed to be smaller than the inner diameter of the rod guide, the inner flange being integrally formed with the tubular portion, and the inner flange that provides the sealing member together with the tubular portion.

[0022]

With the above structure, even if the piston rod is displaced in the radial direction with respect to the rod guide due to lateral vibration or load, the guide ring is radially displaced between the rod guide and the piston rod. To the center of the piston rod so that a uniform gap can be formed over the entire circumference between the piston rod and the guide ring, and the gap should be reduced. You can Further, the seal member is also automatically aligned with the guide ring, and comes into contact with the entire circumference of the piston rod with a uniform force.

[0023]

Embodiments of the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows a first embodiment of the present invention.

In the figure, reference numeral 21 denotes a rod guide according to this embodiment. The rod guide 21 has a large diameter portion whose outer peripheral surface is fitted to the inner peripheral surface of the outer cylinder 1 and an outer peripheral surface of the inner cylinder 2. A stepped cylinder member 21A having a small diameter portion that fits on the surface and a washer member 21B that holds a guide ring 24 and the like, which will be described later, are formed. The inner peripheral side of the rod guide 21 is the piston rod 8
It is a rod insertion hole 21C through which is inserted. Also,
The rod guide 21 is formed with an annular recess 21D having a U-shaped cross section, which is open to the rod insertion hole 21C on the inner peripheral side.
A rod seal 22, an O-ring 23, a guide ring 24, etc., which will be described later, are mounted in the recess 21D.

Reference numeral 22 denotes a rod seal mounted in the recess 21D of the rod guide 21 via a guide ring 24. The rod seal 22 is made of an elastic resin material and has an annular shape similar to the rod seal 13 described in the prior art. The inner peripheral surface of the rod seal 22 is in sliding contact with the piston rod 8 with an interference. In addition, the rod seal 22
An O-ring 23 is mounted between the guide ring 24 and the outer peripheral side of the rod seal 22, and the rod seal 22 and the O-ring 23 form a seal member.

Reference numeral 24 denotes a guide ring provided in the recess 21D of the rod guide 21 so as to be movable in the radial direction. The guide ring 24 has an L-shaped cross section and an O-ring 23.
It is integrally formed from a cylindrical portion 24A located on the outer peripheral side and formed in a cylindrical shape, and an inner flange 24B projecting radially inward from the upper end side of the cylindrical portion 24A. The cylindrical portion 24A holds the rod seal 22 and the O-ring 23 between the inner peripheral side and the piston rod 8, and the inner flange 24B and the rod seal 22 and O between the lower surface side of the recess 21D. Holds ring 23 and holds rod seal 22
Is designed to give a tight margin to the piston rod 8. An annular ring groove 24C extending in the circumferential direction is formed on the upper surface of the guide ring 24.
In C, the guide ring 24 and the recess 2 of the rod guide 21 are provided.
An O-ring 25 that seals between 1D is attached.

The inner flange 24B of the guide ring 24 has an inner diameter slightly larger than the outer diameter of the piston rod 8 and smaller than the inner diameter of the rod insertion hole 21C. Ring 2
A uniform minute gap is provided over the entire circumference between the inner peripheral surface of No. 4 and the inner peripheral surface of No. 4. A radial gap 26 is formed on the outer circumference of the guide ring 24 between the guide ring 24 and the recess 21D of the rod guide 21.
Is allowed to move in the radial direction within the recess 21D of the rod guide 21. And the rod guide 21
When the guide ring 24 moves in the recess 21D in the radial direction, the rod seal 22 and the O-ring 23 housed in the cylindrical portion 24A of the guide ring 24 also move in the radial direction of the rod guide 21 together with the guide ring 24. .

The suspension device according to the present embodiment has the above-mentioned structure, and there is no particular difference in the basic operation thereof from the prior art.

However, in this embodiment, the rod guide 21
A ring-shaped recess 21D is formed in the recess 21D, and a guide ring 24 having an L-shaped cross-section is disposed in the recess 21D so as to be movable in the radial direction. Since the rod seal 22 that is in sliding contact with the outer peripheral surface of the rod 8 is mounted via the O-ring 23, lateral vibration or load acts from the outside between the piston rod 8 and the rod guide 21, and the piston rod 8 moves. Even if the radial displacement occurs in the insertion hole 21C, the guide ring 24 moves radially in the recess 21D of the rod guide 21 via the rod seal 22 and the like, and the piston rod 8
The rod seal 22, the O-ring 23, and the guide ring 24 can be automatically aligned with respect to the axis of, and the gap between the piston rod 8 and the inner peripheral surface of the guide ring 24 is uniform over the entire circumference. It can be maintained at very small intervals,
The rod seal 22 (seal member) can be slidably contacted over the entire circumference of the piston rod 8 with a uniform interference so that the friction with the piston rod 8 can be kept constant.

Thus, even if the piston rod 8 is displaced in the radial direction within the rod insertion hole 21C of the rod guide 21, the guide ring 24 is moved in the radial direction in response to this and the piston rod 8 is automatically aligned. Therefore, the rod seal 22 can be uniformly slidably contacted with the piston rod 8 over the entire circumference, and the rod seal 22 can be protruded between the guide ring 24 and the piston rod 8 or the like.
Partial wear and damage can be prevented.

Particularly, when the piston rod 8 is extended, the rod seal 22 sticks out between the piston rod 8 and the guide ring 24 due to the hydraulic pressure from the oil chamber A, the frictional force due to the extension operation of the piston rod 8, and the like. Such deformation can be effectively prevented by the self-centering of the guide ring 24, and the life and durability of the rod seal 22 can be dramatically improved.

The guide ring 24 is formed in an L-shaped cross section from the cylindrical portion 24A and the inner flange 24B, and the rod seals 22 and O are formed in the recess 21D of the rod guide 21.
Since the ring 23 is held, the guide ring 2
4, the rod seal 22 and the O-ring 23 can be held, and the rod guide 21 can be assembled into the rod guide 21. Therefore, workability at the time of assembling can be improved.

Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted. The feature of this embodiment is that the guide ring 31 is provided in the recess 21D of the rod guide 21 via the bearing 33.

In the figure, 31 is a recess 21 of the rod guide 21.
A guide ring provided in D is shown. The guide ring 31 is composed of a cylindrical portion 31A and an inner flange 31B, which is similar to the guide ring 24 described in the first embodiment. An annular convex portion 31C protruding upward is formed on the outer peripheral side of the upper surface of the inner flange 31B, and an annular ring groove 31 extending in the circumferential direction is formed on the upper surface of the convex portion 31C.
D is formed. An O-ring 32 that seals between the guide ring 31 and the recess 21D is mounted in the ring groove 31D.

Reference numeral 33 denotes a bearing located on the inner peripheral side of the convex portion 31C of the guide ring 31 and provided between the upper surface of the guide ring 31 and the concave portion 21D of the rod guide 21, and the bearing 33 is a guide. Ring 31 is recessed 2
It compensates for smooth radial movement within 1D.

Thus, although the present embodiment having the above-mentioned structure can obtain substantially the same operational effect as that of the first embodiment, in particular, in the present embodiment, the rod guide 2 is used.
The guide ring 31 is installed in the recess 21D of the first bearing 3
3, the guide ring 31 can be smoothly moved in the radial direction by the rotation of the bearing 33 even if the guide ring 31 is pressed upward due to the pressure in the oil chamber A or the like. On the other hand, the guide ring 31 can be surely self-aligned.

In each of the above embodiments, the guide ring 2
4 (31) to the cylindrical portion 24A (31A) and the inner flange 24
Although it is described that the guide ring is formed into an L-shaped cross section from B (31B), instead of this, the guide ring is formed into a U-shaped cross section, and the pair of inner flanges are spaced above and below the tubular portion. May be integrally formed.

In each of the above embodiments, the damping force generating mechanisms 15 and 16 are provided on the piston 7, but
Instead of this, for example, a damping force generating mechanism may be provided in the middle of the pipe 12 connecting the oil hole 8B of the piston rod 8 and the accumulator 11.

Furthermore, in each of the above-mentioned embodiments, the suspension device has been described as an example, but the present invention is not limited to this, and is provided with a rod guide such as an ordinary hydraulic shock absorber, hydraulic cylinder and pneumatic cylinder. It is widely applicable to various cylinder devices.

[0041]

As described above in detail, according to the present invention, an annular guide ring that moves in the radial direction between the rod guide and the piston rod is provided in the recess of the rod guide.
The guide ring is located on the outer peripheral side of the sealing member, and is integrally formed with the tubular portion so as to project radially inward from the tubular portion that holds the sealing member between the piston rod and the piston rod. Since the inner diameter of the inner flange is smaller than the inner diameter of the rod guide, the seal member can be held by the guide ring. In addition to improving the assemblability, even if the piston rod is displaced in the radial direction with respect to the rod guide due to lateral load, the guide ring will automatically align with the piston rod. A uniform minute gap can be secured over the entire circumference. As a result, it is possible to prevent the seal member from entering the gap between the piston rod and the inner peripheral surface of the rod guide and deforming, and it is possible to dramatically improve the life and durability of the seal member. Further, since the seal member is automatically centered together with the guide ring, the seal member is slidably contacted over the entire circumference of the piston rod with a uniform tightening margin.
A problem such as uneven wear of the seal member can be eliminated, and stable performance can be exhibited.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view showing an enlarged main part of a suspension device according to a first embodiment of the present invention.

FIG. 2 is a half sectional view similar to FIG. 1, showing an enlarged main part of a suspension device according to a second embodiment of the present invention.

FIG. 3 is a vertical sectional view showing a suspension device according to a conventional technique.

4 is a half cross-sectional view showing an enlarged main part in FIG.

5 is a half sectional view similar to FIG. 4, showing a deformed rod seal.

[Explanation of symbols]

 2 Inner cylinder (tube) 7 Piston 8 Piston rod 21 Rod guide 21D Recess 22 Rod seal (seal member) 23 O-ring (seal member) 24, 31 Guide ring 24A, 31A Cylindrical part 24B, 31B Inner flange

Claims (1)

[Claims] 1. A tube whose one end is closed, a tubular rod guide provided on the other end of the tube, and a slidably fitted inside the tube, and two oil chambers inside the tube. A piston rod, one end side of which is fixed to the piston and the other end side of which protrudes outside the tube through the rod guide, and an annular seal member which seals between the piston rod and the rod guide. In the cylinder device, the rod guide has an annular concave portion that is open to the inner peripheral surface of the rod guide and has a U-shaped cross section, and the rod guide and the piston rod that are provided in the concave portion. And an annular guide ring that moves in the radial direction between the two, and the guide ring is located on the outer peripheral side of the seal member and holds the seal member between the piston rod and the piston rod. And a sealing member together with the tubular portion, which is integrally formed with the tubular portion at a position opposite to the oil chamber side with respect to the seal member so as to project radially inward from the tubular portion. A cylinder device comprising an inner flange for giving a tightening margin to a member, the inner diameter of the inner flange being smaller than the inner diameter of the rod guide.