JPH09250640A - Seal ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent stick slip due to lubrication failure by forming a plural number of ring projected lines on a moving surface of a seal ring installed in a ring installation groove of a roughly rectangular section provided on an opposite peripheral surface of one member of two cylindrical members to relatively move. SOLUTION: A seal ring 1 used for a fluid pressure instrument is pressurized by a back ring 11 and installed in a ring installation groove of a roughly rectangular section provided on an opposite peripheral surface of either one member of two cylindrical members to relatively move by making opposite peripheral surfaces contact with each other. A plural number of ring projected lines 4 are provided on a moving surface 3 of a seal ring main body 2 of a roughly rectangular section made of an elastic material on such the seal ring 1, and the sectional shape is formed in an R surface. Consequently, it becomes easy to supply a lubricant to the moving surface 3, possible to restrain generation of stick slip by reducing frictional force generated on this moving surface 3 and possible to prevent local extensional deformation of the seal ring 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal device for effectively sealing fluid pressure on a relative movement surface of a fluid pressure device, which seal has a low frictional force generated during movement with a mating cylindrical member. Regarding the ring. In particular, the present invention prevents a local extensional deformation in the rotational direction or the oscillating direction due to the frictional force and the frictional heat due to the rotational motion or the oscillating motion, and prevents stick-slip from occurring during low speed operation. Regarding the ring.

[0002]

2. Description of the Related Art A seal ring used as a sealing device for fluid pressure equipment is made of heat-resistant synthetic resin such as polyimide resin, thermoplastic resin such as polyamide resin, various synthetic resin such as fluorine resin, polyurethane, polyester and the like. A slipper seal made of elastic material such as thermoplastic elastomer or hard synthetic rubber, which has a substantially rectangular cross section and is composed of a seal ring alone or a synthetic rubber back ring having a circular or rectangular cross section. It is used as a seal member. Here, the back ring is an O-ring, a square ring, or the like, and has a function of giving a contact surface pressure to the mating movement surface by applying a compressive deformation force to the seal ring when mounted.

FIG. 6 is a partial sectional view of such a conventional seal ring, showing a case of a seal ring 21 used in combination with a back ring 11. These are mounted in an annular mounting groove (not shown), and are pressed by the back ring 11 so that the moving surface 23 of the seal ring 21 comes into close contact with the mating moving surface (not shown). The illustrated example is the case where the moving surface 23 is the facing outer peripheral surface, but the same applies when the facing inner peripheral surface is the moving surface.

As described above, the seal ring is attached to the mounting groove having a substantially rectangular cross section provided on the opposing peripheral surfaces of the two cylindrical members which move relative to each other, for example, the outer peripheral surface of the piston or the inner peripheral surface of the rod cover. It is used as a sealing device for various fluid pressure devices such as cylinders, valves, joints, etc., which perform reciprocating motion, rotary motion, oscillating motion, and the like.

A sealing device in which such a seal ring is usually used alone or in combination with a back ring is
Especially in the case of a conventional seal ring with a flat moving surface, during reciprocating movement, fluid easily enters the moving surface, so an oil film is sandwiched between it and the mating moving surface, and the oil film is sliding and good lubrication is achieved. Since the person is exercising in a normal state, the frictional force does not become abnormal. That is, in the reciprocating motion in which the contact between the seal ring and the mating movement surface is surface contact, there is no problem of poor lubrication because the oil film is always present on the contact surface.

However, during a slight stroke (stroke equal to or less than the axial dimension of the seal ring) or at low speed operation, it becomes difficult for a new oil film to enter the moving surface, resulting in problems such as increased friction and wear. This tendency becomes more remarkable as the pressure increases.

Similarly, in the rotary motion or the oscillating motion, since the same peripheral surface of the mating motion surface is in contact with the seal ring, it is necessary to move in a state where new lubricant is difficult to be supplied to the contact surface. I won't. Therefore, along with the deterioration of the lubrication state, the friction (rotational torque) rises, wear, and the relative motion of the same member makes it difficult to dissipate heat, and frictional heat tends to accumulate.

In addition, when such a minute stroke operation or a low speed operation is performed under high pressure conditions, or during rotational movement or rocking movement, it becomes difficult for the working fluid to enter the moving surface of the seal ring, and the lubrication state becomes worse. May be.

For example, under a high-frequency, small-quantity stroke motion condition under high pressure, it becomes difficult for lubricant to enter the motion surface of the seal ring, so that the lubrication state of the motion surface is extremely deteriorated, wear is promoted, and friction heat is also affected. As a result, the strength of the seal ring is reduced, resulting in protruding deformation, which may lead to fluid leakage or damage to the seal ring.

In a sealing device using such a seal ring, when the lubrication state of the moving surface is deteriorated, the frictional force is increased and smooth operation is impeded, resulting in malfunction such as stick-slip.

Further, even in the rotational movement or the oscillating movement at a high pressure, as described above, the lubricant is hard to enter the moving surface of the seal ring, so that the lubricating state of the moving surface is deteriorated and the frictional force is increased to further increase the frictional heat. Influence, for example, when the material of the seal ring is a thermoplastic resin such as a polyamide resin, the strength of the seal ring may be further reduced, and if an unbalanced load is further applied to such a state, the seal ring There was a case where it was stretched and deformed locally in the direction of rotation and damaged.

For example, in a seal ring used for a rotating or oscillating motion part of a swivel joint of a hydraulic machine whose pressure is increasing such as construction machinery such as a recent truck crane and power shovel, There is a problem in that operability and device reliability are reduced due to stick-slip.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the frictional force between the seal ring and the mating moving surface, which is seen during movement, to be low, so that the operation of the fluid pressure device can be made smooth without stick-slip or the like. An object of the present invention is to provide a seal ring which has good operating characteristics and is capable of preventing local extensional deformation due to increase in frictional force of the seal ring during rotational movement or rocking movement.

More specifically, an object of the present invention is to prevent stick-slip caused by poor lubrication when used for a cylinder of a servo-type hydraulic device which is operated under a high pressure, particularly in a minute stroke or at a low speed. The purpose is to provide a seal ring that can be used for.

[0015]

Means for Solving the Problems The inventors of the present invention have repeatedly studied a conventional seal ring to achieve such an object,
We focused on the following points.

That is, the frictional force generated on the relative moving surface of the seal ring is determined by the contact surface stress of the seal ring and the friction coefficient of the material. It is known that the frictional force is reduced by improving it. For that purpose, it is only necessary to be able to supply the lubricant to the moving surface forming the boundary or to improve the retaining property of the lubricant.

The structure capable of exhibiting such a function was examined, and the following constitution was adopted in the present invention. Multiple annular ridges are provided on the moving surface of the seal ring. By adopting such a configuration, the lubricant can be easily retained in the recesses between these ridges.

The tip of the annular protrusion is the R surface. As a result, the sealability of the seal ring can be maintained, and the lubricant becomes wedge-shaped on the contact surface, making it easier to enter and improving the lubricity. Furthermore, the recess formed between the annular ridges is used for retaining the lubricant. It is possible to suppress the generation of frictional force and frictional heat generated on the relative movement surface as a groove.

By adopting the above-mentioned structure, particularly when the seal ring is manufactured by injection molding, the removability of the product from the mold is improved, the radial projection amount of the annular projection is reduced, and By rounding the tip of the strip, workability becomes even easier. Further, by providing the R surface also at the corner portion of the protrusion on the seal ring body side, the corner on the convex side of the mold is rounded, so that workability is further improved.

As described above, by providing annular ridges in multiple stages on the moving surface of the seal ring, preferably by rounding the tips of the annular ridges, or by making the tops of the ridges flat surfaces. By providing the R surface on the ridge, more preferably by providing the R surface also on the corner portion of the protrusion on the seal ring main body side, the lubricant is easily supplied to the relative motion surface forming the boundary surface, and the relative motion is prevented. The present invention was completed when it was found that a frictional force generated on the surface can be reduced and a seal ring having good molding workability by injection molding can be obtained.

According to the present invention, the annular mounting groove having a substantially rectangular cross section is provided on the opposing peripheral surface of either one of the two cylindrical members which are in contact with each other and move relative to each other. A substantially rectangular cross section made of an elastic material, characterized in that a plurality of annular ridges are provided on the moving surface that is pressed against the opposing moving surface side that is the opposing peripheral surface to seal the fluid pressure. It is a seal ring.

According to a preferred embodiment of the present invention, the tips of the annular ridges may be rounded, or the tops of these annular ridges may be flat surfaces and R surfaces may be provided at both ends thereof. In still another aspect, an R surface is also provided at a corner portion of the annular projection on the seal ring body side.

The number of steps provided with the protrusions is not particularly limited, but at least two steps may be provided although it is related to the size thereof, and preferably the number of steps is provided only over the entire movement surface.

[0024]

FIG. 1 is a partial sectional view of a seal lip according to the present invention, FIG. 2 is an enlarged view of a moving surface thereof, and FIG. 3 is a state in which the seal lip is mounted in a mounting groove provided on an opposing peripheral surface. FIG.

A seal ring 1 according to the present invention, which constitutes a seal device for sealing fluid pressure, has a plurality of annular ridges 4 provided on a moving surface 3 of a seal ring body 2 having a substantially rectangular cross section made of an elastic material. . As shown in FIG. 2, the cross-sectional shape of the annular protrusion 4 is rounded at its tip, that is, forms an R surface. In the illustrated example, the moving surface is provided on the outer peripheral surface of the seal ring 1, and the seal ring 1 is a back ring.
Pressed by 11.

As shown in FIG. 3, the seal ring 1 according to the present invention is provided on the opposing peripheral surface of either one of two cylindrical members which are in contact with each other and relatively move. It is mounted in the annular mounting groove 16 having a substantially rectangular cross section,
At this time, the seal ring 1 may be a single piece, but as shown in the figure, it is made of a soft elastic material such as synthetic rubber and is attached together with the back ring 11 for pressing the seal ring against the opposing movement surface 15 side which is the opposite peripheral surface. May be.

As described above, in the present invention, by providing the minute annular projections 4 in multiple stages on the moving surface of the seal ring 1, it becomes easier to supply the lubricant to the relative moving surface of the seal ring. Since it is possible to reduce the frictional force that occurs on the dynamic motion surface, it is possible to suppress the occurrence of stick-slip during sliding motion during low-speed operation under high pressure, and to suppress the generation of frictional heat during rotary motion. This prevents local extensional deformation of the seal ring.

Preferably, the above-mentioned annular projection has a cross-sectional shape with a rounded tip, or a flat top surface with R surfaces at both ends, whereby a die for a product at the time of injection molding is formed. To facilitate removal from the
It is possible to obtain a seal ring having good workability, which is almost equivalent to the conventional seal ring 21 having a flat moving surface 23 shown in FIG.

FIG. 3 shows an example in which the ridge 4 has a round cross-section. FIG. 4 is a partially enlarged view of the moving surface of the seal ring 1, which is a modification of FIG. 2, in which the tops of the ridges 4 provided on the moving surface 3 form flat surfaces, and R at both ends thereof.
An example of the case where a surface is provided is shown. As shown in the illustrated example, the annular projection 4 is provided with the flat surface portion 6 at the top thereof and the both ends thereof are R surfaces, so that a lubricating coating on the contact surface is easily formed, wear of the contact surface is reduced, and durability is maintained and improved. It is preferable from the point. Further, it is also effective to improve workability by providing R-faces 8 at the corners of the ridge 4 on the seal ring body side and forming tapered faces 7 between the R-faces at both ends of the flat portion 6.

As described above, in the seal ring 1 according to the present invention, since the contact with the surface of the mating cylindrical member is the tip portion of the ridge 4, a large number of minute annular contact surfaces are formed, and the seal ring 1 Since the contact surface area of the moving surface 3 as a whole is small, the contact surface pressure of each contact portion of each ridge is high and the sealing performance is improved. Moreover, since the tip of each protrusion 4 has a rounded surface, it becomes easy for an oil film to enter between the contact surfaces formed on the opposed peripheral surfaces.

Due to the structure of the moving surface of the seal ring 1 as described above, the surface pressure of the contact portion of each ridge 4 becomes high so that no leakage occurs even when a high pressure is applied and the mating surface of the ridge 4 is The distribution of the contact surface pressure with respect to the contact surface pressure does not steeply rise at both ends of the contact surface pressure, so that an oil film can easily enter the contact surface and a good lubrication state can be maintained. Moreover, the oil film that has passed through the contact surface is retained in the concave portion between the contact surface and the next contact surface, thereby making it possible to substantially eliminate the poor lubrication state.

FIG. 5 is a schematic view showing a modified example of the cross-sectional shape of these projections 4, and the R surface is provided at the tip or the tip side of each annular projection of FIGS. 5 (a) to 5 (c). 5 (d) to 5 (f) are shown in FIGS. 5 (a) to 5 (c), respectively.
In addition to the modified example, an example of a ridge provided with an R surface on the main body side of the annular ridge is also shown.

In the present invention, there are no particular restrictions on the height and the number of steps of the projections 4 provided in multiple steps on the moving surface 3, and for example, FIG.
When viewed from the cross section of, the ratio of the total length of the protrusions (l ₁ + l ₂ + ...) to the total length L of the moving surface 3 is about 20 to 60% from the viewpoint of the balance between the sealing property and the frictional force. preferable. It is more preferably 40 to 50%.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation and effect of the present invention will be described more specifically based on its embodiments with reference to the accompanying drawings. As shown in FIG. 2, the tips of the plurality of ridges 4 provided on the moving surface 3 of the seal ring 1 having a substantially rectangular cross section are constituted by R surfaces.

The radial height of the ridge 4 is 0.02 mm to 0.2.
mm, the interval between the protrusions is in the range of 0.5 mm to 1 mm, and is set depending on the diameter of the seal ring, the operating conditions such as operating pressure, and the material of the sealing ring.

(Example 1) This example evaluates the characteristics at low speed operation. In a reciprocating motion at a working pressure of 35 MPa, the seal ring material is made of a hard polyamide resin and the outer diameter of the seal ring is 100 mm. A flat section with a tip of 0.2 mm and a taper surface of approximately 30 degrees at both ends of the flat section, and corners of the tip flat section and the taper surface with a R surface of R0.1 and a ridge 4 with a height of 0.05 mm. Twelve strips were provided at intervals of 0.5 mm.

(Embodiment 2) In the rotational movement at a working pressure of 21 MPa, the seal ring material is a soft polyamide resin, and the seal ring has an outer diameter of 60 mm.
The height was 0.05 mm and the distance between each ridge was 0.25 mm, and 14 ridges were provided.

[0038]

[Table 1]

[0039]

As shown in the above embodiment, the seal ring 1 of the present invention having a plurality of ridges on the moving surface is compared with the conventional seal ring 21 having a flat moving surface 23 of FIG. Then, as shown in Table 1, in the reciprocating motion, the leak amount of the lubricating oil became about 1/5 in the hermeticity.

Also, the operating speed at which stick-slip occurs is 2 mm / s, compared to 7 mm / sec of the conventional seal ring.
It becomes ec, and it is greatly improved in low speed operation.
Also in the rotational movement, as shown in Table 1, the torque was reduced by about 30% as compared with the conventional seal ring, and the local extension deformation of the seal ring was not observed.

As described above, the seal ring of the present invention is provided with a large number of minute projections whose contact surface or the end portion of the contact surface is the R surface on the moving surface. In addition to improving the sealing performance and low speed operation characteristics in reciprocating motion, it is easy to maintain the lubrication state of the seal surface in rotating motion, as described in the examples in terms of performance. The effect of reducing local elongation deformation of the seal ring is obtained.

[Brief description of drawings]

FIG. 1 is a one-sided sectional view of a sealing device in which a seal ring according to the present invention is combined with a square ring type back ring.

FIG. 2 is an enlarged view of a cross-sectional portion of the seal ring shown in FIG.

FIG. 3 is a cross-sectional view showing a piston mounting example of a sealing device in which the seal ring of the present invention is combined.

FIG. 4 is a sectional view of another embodiment of the seal ring according to the present invention.

5 (a) to 5 (f) are partial schematic cross-sectional views showing an example of changing the cross-sectional shape of the ridge.

FIG. 6 is a one-sided sectional view of a sealing device in which a conventional seal ring and a square ring type back ring are combined.

[Explanation of symbols]

1: Seal ring 2: Seal ring body 3:
Movement surface 4: Ridges 5: Recesses 6:
Flat surface 7: Tapered surface 8: R surface 11: Back ring 15: Opposite movement surface 16: Annular mounting groove 21: Seal ring 23:
Exercise surface

Claims (1)

[Claims] 1. A seal ring mounted in an annular mounting groove having a substantially rectangular cross section, which is provided on the opposing peripheral surface of one of two cylindrical members that are in relative contact with each other and are in contact with each other. A seal ring having a substantially rectangular cross-section made of an elastic material, characterized in that a plurality of annular projections are provided on the moving surface that is pressed against the opposing moving surface, which is the opposing peripheral surface, to seal the fluid pressure.