JP2004183799A - Sliding part seal structure - Google Patents

Abstract

An object of the present invention is to improve the sealing performance between one member and the other member and to increase the production cost of the seal.
The other member (S) is provided with a U packing (1) and a backup ring (B) for supporting the U packing (1). The U packing (1) has an annular inner lip (R1) and lip tips (6) formed on the inner peripheral side of the inner lip (R1). And a sloping surface 10 connected to the lip tip 6. The backup ring B includes an annular main body 9a and a rising portion 9b rising from the main body 9a and abutting on the sloping surface 10. And the inner peripheral surface of the backup ring B is slid in contact with the outer periphery of the one member M to seal the gap between the one member M and the other member S under lubrication. 9b was formed in a truncated cone shape, and a gap K was formed between the U packing 1 and the backup ring B.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seal structure for a sliding portion, and more particularly to an improvement in a U-packing and a backup ring.
[0002]
[Prior art]
As a seal structure for sealing a sliding portion, the structure shown in FIG. 5 is conventionally known. The seal structure of the sliding portion is used, for example, to seal between a piston rod as one member of the hydraulic shock absorber and a seal case as the other member. To prevent the lower part of the inner lip 33 from crimping against the piston rod while the U-packing 30 is loaded with hydraulic pressure from the concave portion 32 side, and the inner lip 33 of the U-packing 30 to the piston rod. It is slidably contacted (for example, see Patent Literature 1), and is disposed near the end of the hydraulic shock absorber so as to bring the inside of the hydraulic shock absorber into a liquid honey state.
[0003]
[Patent Document 1]
JP-A-2000-130492 (from page 18, right column, line 18 to page 3, right column, line 32, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, there is a fear that the following disadvantages may be pointed out in the above-described conventional seal structure of the sliding portion. That is, in the above configuration, although the U packing 30 is prevented from pressing the lower portion of the inner lip 33 against the piston rod 37 under the state where the U packing 30 is loaded with the hydraulic pressure from the recess 32 side by the backup ring 36, the U packing 30 is elastic. The back lip 33 is made of a material, the tip of the inner lip 33 to be pressed against the piston rod projects from an extension of the inner periphery of the backup ring 36, and the back lip 33 of the U packing 30 slides on the piston rod. As shown in FIG. 6, when the hydraulic pressure is applied from above in the figure, the U-packing 30 comes into contact with the upper end of the backup ring 36 of the inner lip 33 of the U-packing 30 because the U-packing 30 is in contact with the vicinity of the contacting portion. The part which is located between the upper end of the backup ring 36 and the piston rod 37 Intrudes into the gap such.
[0005]
Then, the distribution of the surface pressure received from the piston rod 37 on the inner lip 33 of the U packing 30 is as shown by the line P2 in the drawing, and particularly, in the vicinity of the portion of the inner lip 33 of the U packing 30 in contact with the upper end of the backup ring 36. The contact pressure gradient θ3 is larger than the contact pressure gradient θ4 on the upper side of the inner lip 33 in the drawing.
[0006]
Then, since the thickness of the oil film attached to the piston rod 37 when passing through the U packing 30 is inversely proportional to the square root of the contact pressure gradient, when the piston rod 37 moves downward in FIG. When the piston rod 37 moves upward in the drawing, that is, when the hydraulic shock absorber contracts, the thickness depends on the contact pressure gradient θ3. . That is, the thickness of the oil film attached to the piston rod 37 when the hydraulic shock absorber extends is greater than the thickness of the oil film attached to the piston rod 37 when the hydraulic shock absorber contracts.
[0007]
Here, the above phenomenon will be described with reference to a model diagram of a change in oil film thickness when the piston rod 37 reciprocates with respect to the cylinder C shown in FIG. When the contact pressure gradient θ4 is larger than the contact pressure gradient θ3 as in the structure, the piston rod L retreats from the cylinder C as shown in FIG. 7, that is, the hydraulic shock absorber extends and passes through the U packing 30. In this case, the thickness of the oil film of the oil O attached to the piston rod 37 becomes H1, while the piston rod 37 intrudes into the cylinder C, that is, the hydraulic shock absorber contracts and passes through the U packing S. Since the thickness of the oil film of the oil O attached to the rod 37 is H2, the oil O corresponding to the difference ΔH between the thickness H1 and the thickness H2 can return into the cylinder C. Kunar.
[0008]
For this reason, when the hydraulic pressure is applied to the U-packing 30 from above in FIG. 5, the oil film attached to the piston rod 37 is easily scraped, which may lead to oil leakage.
[0009]
Furthermore, the backup ring is shaped so as to cover the U packing up to the vicinity of the portion where the inner lip slides on the piston rod, and the backup ring is often made of synthetic resin, and synthetic resin is relatively expensive. However, the production cost is also increased.
[0010]
In addition, in the processing of this type of conventional backup ring, first, it is common to first form a base material by sintering and then form the base material into the above-described shape by cutting, and particularly to process the upper end portion of the backup ring. Since it is difficult, processing is troublesome, and the production cost is also deteriorated in this respect.
[0011]
Therefore, an object of the present invention was created in order to improve the above-mentioned adverse effects, and an object thereof is to improve the sealing property between one member and the other member, Another object is to increase the production cost of the seal.
[0012]
[Means for Solving the Problems]
The sealing structure of the sliding portion in the first problem solving means of the present invention is such that one member is movably inserted into another hollow member, and the other member is provided with U packing and a backup ring supporting the U packing, The U-packing includes an annular inner lip, a lip tip formed on the inner peripheral side of the inner lip, and a slope connected to the lip tip. The backup ring rises from the body and comes into contact with the slope. A lip tip is pressed into contact with one member, the inner peripheral surface of the backup ring is slid in contact with the outer periphery of one member, and the other member is sealed under lubrication. The rising portion is formed in a frusto-conical shape, and a gap is formed between the U packing and the backup ring.
[0013]
Further, the seal structure of the sliding portion in the second means for solving the problem of the present invention is such that one member is movably inserted into another hollow member, and the other member includes a U-packing and a backup ring supporting the U-packing. The U-packing includes an annular outer lip, a lip tip formed on the outer peripheral side of the outer lip, and a slope connected to the lip tip, and the backup ring has an annular body on the slope and rises from the body. A slidable part that presses the tip of the lip against one member, makes the outer peripheral surface of the backup ring slidably contact the inner periphery of one member, and seals the inside of the other member under lubrication. In the seal structure of the portion, the rising portion is formed in a mortar shape, and a gap is formed between the U packing and the backup ring.
[0014]
Even when the fluid pressure is applied from the concave side of the U packing and the lip is pressed against one member side, the U packing and the backup ring have the above-mentioned shape, and the gap is provided between the U packing and the backup ring. When the U-packing is deformed due to the application of fluid pressure from the concave portion of the U-packing, the lip of the U-packing is not pushed into the entire gap, and the contact pressure near the contact portion between the backup body side of the lip and one of the members. Since the gradient is smaller than the contact pressure gradient in the vicinity of the contact portion between the side on which the hydraulic pressure of the lip is loaded and the one member, even if one member reciprocates in the other member, the lip may be an oil film or the like. There is no scraping of the lubricating film, and the sealing performance is improved.
[0015]
In addition, the gap between the U-packing and the backup ring functions as a lubricant reservoir, and the lubricant accumulated in the gap can make the movement of one member smoother. The effect of reducing the frictional force of the lip of the U packing and suppressing the wear is enhanced, and the effect of extending the service life of the U packing can be expected.
[0016]
In addition, since the backup ring has the above-described shape, the backup ring does not need to cover the U-packing to the vicinity of the portion where the lip is in sliding contact with the one member, so that the material of the backup ring can be reduced as compared with the conventional backup ring. Therefore, the production cost can be improved, and unlike the conventional backup ring, the upper end portion has a frusto-conical shape, so that the processing is simple, and the production cost is also improved in this respect.
[0017]
Further, in the seal structure of the sliding portion in the third means for solving the problem of the present invention, in the first or second means for solving the problem, a metal core is provided inside the U packing.
[0018]
Therefore, in this case, even if fluid pressure is applied to the concave portion of the U packing, the elastic deformation of the U packing can be suppressed, so that an increase in the sliding contact pressure can be suppressed. In other words, the movement of the one member can be made smoother, the frictional force of the lip of the U-packing can be further reduced, and the effect of suppressing wear can be further enhanced. The effect is high.
[0019]
Further, in the seal structure of the sliding portion in the fourth problem solving means of the present invention, in the first or second problem solving device, the other member is a cylinder or an outer cylinder of the hydraulic shock absorber or a member connected to them. Wherein one member is a piston rod.
[0020]
In this case, even if the piston rod reciprocates in the cylinder, the lip of the U packing does not scrape off the oil film attached to the piston rod, thereby improving the sealing performance and leaking oil. There is no. That is, since the oil leak is effectively prevented, the function of the hydraulic shock absorber can be maintained.
[0021]
Further, since the U-packing is in sliding contact with the piston rod of the hydraulic shock absorber, the hydraulic oil attached to the piston rod can be stored in the gap. The movement of the U packing can be made smoother, and the effect of reducing the frictional force of the lip of the U packing and the effect of suppressing abrasion are further enhanced, and the effect of extending the life of the U packing is also high.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
In the description of the present embodiment, the present invention will be described in detail below assuming that the present invention is embodied in a hydraulic shock absorber. The basic embodiment of the present invention is composed of a U packing 1 and a backup ring B as shown in FIG. The U packing 1 is formed in an annular shape having a concave portion 2, and has an annular inner lip R <b> 1 and an annular outer lip R <b> 2 bordering the concave portion 2. A lip tip 6 formed on the inner peripheral side of the inner lip of the U packing 1, an inclined surface 10 connected to the lip tip 6, and a horizontal contact surface 7 connected to the inclined surface 10 are provided. It is in pressure contact with the barrel piston M. The U packing 1 is fitted in the seal case S as the other member, the outer lip R2 of the U packing 1 is abutted on the seal case S, and the tip 6 of the inner lip R1 of the U packing 1 is attached to the piston rod M as one member. Sliding contact.
[0023]
Although not shown, for example, the hydraulic shock absorber includes a cylinder filled with hydraulic oil and a piston rod M movably inserted into the cylinder via a piston, and can generate an appropriate damping force. In the case of the above-described hydraulic shock absorber, the seal structure of the present embodiment is provided between the seal case S provided at the cylinder end and the piston rod M. The concave portion 2 of the U-packing 1 is used under a condition in which hydraulic pressure is applied to the concave portion 2 toward the inside of the cylinder (not shown).
[0024]
The backup ring B includes an annular main body 9a and rising portions 9b rising from the main body 9a and abutting on the inclined surfaces 10, respectively. The inner peripheral surface 9d of the backup ring B is provided on the outer periphery of the piston rod M as one member. The rising portion 9b is formed in a frusto-conical shape, and the inner peripheral surface 9d of the backup ring B is made to extend substantially in the same extension as the lip tip 6. Is slightly protruded from the inner peripheral surface 9d toward the piston rod M as one member.
[0025]
Then, the inclined surface 10 of the inner lip R1 of the U packing 1 is brought into contact with the outer periphery 9c of the rising portion 9b of the backup ring B, and the horizontal contact surface 7 continuing from the inclined surface 10 is brought into contact with the upper surface of the main body 9a. A gap K is provided between the backup ring B and the U packing 1, that is, between the rising upper surface 9 e of the backup ring B and the inclined surface 10 of the inner lip R 1 of the U packing 1.
[0026]
By the way, when the hydraulic shock absorber expands and contracts, that is, when the piston rod M moves up and down with respect to the cylinder in the figure, the hydraulic oil is loaded with pressure by the piston provided on the piston rod M. , The hydraulic pressure is also applied to the concave portion 2 of the U packing 1.
[0027]
Then, since this hydraulic pressure acts in the direction of expanding the concave portion 2 of the U packing 1, the inner lip R1 of the U packing 1 which is in sliding contact with the piston rod M is pressed against the piston rod M, and the outer lip R2 is pressed against the seal case S. It will be imposed.
[0028]
However, a gap K is provided between the inclined surface 10 of the inner lip R1 of the U packing 1 of the present embodiment and the outer periphery 9c of the rising portion 9b of the backup ring B, and the rising portion 9b of the backup ring B is planted. Fluid pressure is applied from the concave portion 2 side of the U-packing 1 because the outer periphery 9c is inclined to the inner peripheral side so as to reduce the diameter toward the upper side in the figure with respect to the main body 9a. Then, the inner lip R1 is pressed against the piston rod M, which is the one member side, and the inclined surface 10 of the inner lip R1 bends toward the gap K. However, the inner lip R1 hits the corner formed by the outer periphery 9c of the backup ring B and the rising upper surface 9e. Stress is received at the portion of the U-packing 1 in contact with the inner ring R1, which suppresses bending deformation of the inner lip R1 abutting on the inclined surface 9c of the backup ring B, and the inner lip R1 is pushed into the entire gap K. It is suppressed.
[0029]
At this time, the distribution of the surface pressure received from the piston rod M on the inner lip R1 of the U packing 1 is as shown by a curve P1 in FIG. 2, and the upper part of the inner lip R1 of the U packing 1 in the drawing comes into contact with the piston rod M. The contact pressure gradient θ2 at the portion where the piston ring M contacts the backup ring B side of the inner lip R1 is larger than the contact pressure gradient θ1 at the portion where the piston rod M is in contact.
[0030]
Then, since the thickness of the oil film attached to the piston rod M when passing through the U packing 1 is inversely proportional to the square root of the contact pressure gradients θ1 and θ2, when the piston rod M moves downward in the drawing, that is, When the hydraulic shock absorber expands, the thickness depends on the contact pressure gradient θ2. When the piston rod M moves upward in the drawing, that is, when the hydraulic shock absorber contracts, the thickness depends on the contact pressure gradient θ1. It will be thick. That is, the thickness of the oil film attached to the piston rod M when the hydraulic shock absorber is extended is larger than the thickness of the oil film attached to the piston rod M when the hydraulic shock absorber is contracted. Conversely, it becomes thin.
[0031]
Therefore, the inner lip R1 of the U packing 1 is prevented from scraping off the oil film attached to the piston rod M, and the sealing property is improved, and no oil leaks. That is, since the oil leak is effectively prevented, the function of the hydraulic shock absorber can be maintained.
[0032]
In addition, since hydraulic oil is attached to the piston rod M, the gap K functions as a pool of hydraulic oil, and the hydraulic oil collected in the gap K makes the piston rod move smoothly. In addition to the above, the reduction of the frictional force and the wear of the inner lip R1 of the U packing 1 are further suppressed, so that the effect of extending the life of the U packing is also high.
[0033]
In addition, since the backup ring B has the above-described shape, the backup ring B does not need to cover the U-packing 1 up to the vicinity of the tip 6 which is the sliding contact surface where the inner lip R1 is in sliding contact with the piston rod M. it can. Therefore, production costs can be improved.
[0034]
Further, unlike the conventional backup ring, the upper end has a frusto-conical shape, so that the processing is simple, and the production cost is also improved in this respect.
[0035]
If the inner lip R1 of the U-packing 1 is formed to be thicker, the bending strength of the inner lip R1 becomes stronger when hydraulic pressure is applied to the concave portion 2 of the U-packing 1, so that the inner lip R1 is less likely to be elastically deformed. The increase in the sliding contact pressure can be further suppressed.
[0036]
In the present embodiment, the case where the U packing 1 and the backup ring B are slid on the piston rod M, which is one member, has been described. On the contrary, the one member is provided on the outer peripheral side of the U packing and the backup ring. In correspondence with the position, a lip tip formed on the outer peripheral side of the outer lip of the U packing and an inclined surface connected to the lip tip are formed, and the outer lip of the U packing is slidably contacted with one member to back up. The ring is constituted by an annular main body on the inclined surface and a rising portion rising from the main body and abutting on the inclined surface, the rising portion is formed in a mortar shape, and the outer peripheral surface of the backup ring is substantially equal to the lip tip. Even if the space is formed on the same extension line and a gap is formed between the U packing and the backup ring, the above-described effects can be achieved. It is.
[0037]
Further, as shown in FIG. 3, the backup ring 13 is formed by an annular main body 9a and a frustoconical rising portion 13b rising from the main body 9a, and in the drawing of the inner lip R1 of the U packing 11 in the drawing. The lower part on the inner peripheral side may be shaped along the backup ring 13. Even in this case, a gap is still formed between the backup 13 and the inner peripheral surface of the inner lip R1 of the U-packing 11, and the outer periphery of the rising portion is formed on the inner peripheral side so as to reduce its diameter upward in the drawing. Due to the inclination, the above-described operation and effect can be obtained.
[0038]
Subsequently, a modified example of the present embodiment will be described. Since the description of the same members will be repeated, the detailed description thereof will be omitted by only assigning the same reference numerals. In this modification, as shown in FIG. 3, a core metal 21 is provided inside a U-packing 20. As in the above-described embodiment, the inner lip R3 is provided with a piston rod M of a hydraulic shock absorber. The backup ring B is brought into contact with the lower surface of the outer periphery of the inner lip R3 to fit into the seal case S for use.
As a result, even if hydraulic pressure is applied to the concave portion 22 of the U-packing 20, the elastic deformation of the U-packing 20 is further suppressed by the core metal 21 provided therein. It is possible to suppress an increase in the surface pressure in sliding contact with the U packing 20. That is, since an increase in the sliding contact surface pressure can be prevented, the movement of the piston rod M can be made smooth, and the frictional force and wear of the inner lip R3 of the U-packing 20 can be further reduced as compared with the related art. Is suppressed, so that the life of the U packing can be extended.
[0039]
【The invention's effect】
According to the invention of each claim, even when the fluid pressure is applied from the concave side of the U packing and the lip is pressed against the one member side, the U packing and the backup ring are formed in the above shape, and the U packing and the backup ring are formed. When the U-packing is deformed by applying a fluid pressure from the concave portion of the U-packing, the lip of the U-packing is not pushed into the entire gap, and the lip of the lip and the one side member The contact pressure gradient in the vicinity of the contact portion with the lip becomes smaller than the contact pressure gradient in the vicinity of the contact portion between the lip where the hydraulic pressure is applied and the one member, so that one member reciprocates in the other member. However, the lip does not scrape off a lubricating film such as an oil film, and the sealing property is improved.
[0040]
In addition, the gap between the U-packing and the backup ring functions as a lubricant reservoir, and the lubricant accumulated in the gap can make the movement of one member smoother. The effect of reducing the frictional force of the lip of the U packing and suppressing the wear is enhanced, and the effect of extending the service life of the U packing can be expected.
[0041]
In addition, since the backup ring has the above-described shape, the backup ring does not need to cover the U-packing to the vicinity of the portion where the lip is in sliding contact with the one member, so that the material of the backup ring can be reduced as compared with the conventional backup ring. Therefore, the production cost can be improved, and unlike the conventional backup ring, the upper end portion has a frusto-conical shape, so that the processing is simple, and the production cost is also improved in this respect.
[0042]
Furthermore, according to the third aspect of the invention, when a fluid pressure is applied to the concave portion of the U packing, the bending strength is further increased, the elastic deformation is less likely to occur, and an increase in the sliding contact pressure can be suppressed. Therefore, the movement of the one member can be made smoother, and the effect of reducing the frictional force of the inner lip of the U-packing and suppressing the wear can be further enhanced, so that the effect of extending the life of the U-packing is also high.
[0043]
Further, according to the invention of claim 4, even if the piston rod reciprocates in the cylinder, the lip of the U packing does not scrape off the oil film attached to the piston rod, thereby improving the sealing performance and leaking oil. Nothing. That is, since the oil leak is effectively prevented, the function of the hydraulic shock absorber can be maintained.
[0044]
Further, since the U-packing is in sliding contact with the piston rod of the hydraulic shock absorber, the hydraulic oil attached to the piston rod can be stored in the gap. The movement of the U packing can be made smoother, and the effect of reducing the frictional force of the lip of the U packing and the effect of suppressing abrasion are further enhanced, and the effect of extending the life of the U packing is also high.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a seal structure of a sliding portion in the present embodiment.
FIG. 2 is a diagram showing a pressure distribution in a seal structure of a sliding portion in the present embodiment.
FIG. 3 is a longitudinal sectional view of a seal structure of a sliding portion in another configuration.
FIG. 4 is a longitudinal sectional view of a U-packing according to a modification of the present embodiment.
FIG. 5 is a longitudinal sectional view of a conventional seal structure for a sliding portion.
FIG. 6 is a diagram showing a pressure distribution in a conventional seal structure of a sliding portion.
FIG. 7 is a model diagram showing a change in the thickness of an oil film when a piston rod having a conventional seal structure for a sliding portion reciprocates with respect to a cylinder.
[Explanation of symbols]
1, 11, 20 U packing 2, 22 recess 6 lip tip 7 abutment surface 9a, 13a body 9b, 13b rising part 9c inclined surface 9d The inner circumferential surface of the rising part and the inner circumferential surface of the hole of the body are flush with each other. Sliding contact surface 9e Rising upper surface 10 Inclined surface 21 Metal core B, 13 Backup ring K Gap M Piston rods R1, R3 serving as one member Inner lip R2 Outer lip S Seal case serving as the other member

Claims (4)

One member is movably inserted into the other hollow member, and the other member is provided with U packing and a backup ring for supporting the U packing, and the U packing is formed on the annular inner lip and the inner peripheral side of the inner lip, respectively. The backup ring includes an annular main body, and a rising portion that rises from the main body and abuts on the inclined surface. The inner peripheral surface of the sliding member is slidably contacted to the outer periphery of the one member, in the sealing structure of the sliding portion that seals between the one member and the other member under lubrication, the rising portion is formed in a frusto-conical shape, and And a gap between the U-packing and the backup ring. One member is movably inserted into the other hollow member, and the other member is provided with U packing and a backup ring for supporting the U packing. The U packing is formed on the outer peripheral lip of the annular outer lip and on the outer peripheral side of the outer lip, respectively. The backup ring includes a lip tip and an inclined surface connected to the lip tip, and the backup ring includes an annular main body on the inclined surface, and a rising portion rising from the main body and abutting on the inclined surface. In the seal structure of a sliding portion in which the outer peripheral surface of the backup ring is slidably contacted with the inner periphery of one member and the other member is sealed under lubrication, the rising portion is formed in a mortar shape, and the U packing is used. A seal structure for a sliding portion, wherein a gap is formed between the sliding ring and the backup ring. The seal structure for a sliding portion according to claim 1 or 2, wherein a core metal is provided inside the U packing. The seal structure for a sliding part according to claim 1 or 3, wherein the other member is a cylinder or an outer cylinder of the hydraulic shock absorber or a member connected to the cylinder or the outer cylinder, and one member is a piston rod.

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