KR20110013277A - Sealing apparatus - Google Patents

Abstract

PURPOSE: A sealing device is provided to ensure good sealability even through it is made of a material having low hardness for easy installation. CONSTITUTION: A sealing device comprises an annular base(10), a first rib(11), a second lip(12), and a water pressure groove. The annular base is received in an annular groove formed in a housing. The first rib contacts the bottom surface of the annular groove. The second rib contacts and slides on the circumferential surface of another member. The water pressure groove is opened to high pressure side between the first rib and the second rib, thereby improving the airtight seal between the first and second ribs.

Description

Sealing Device {SEALING APPARATUS}

The present invention relates to a sealing device for use in a hydraulic cylinder or the like.

With reference to FIGS. 8-10, the sealing apparatus which concerns on a prior art is demonstrated. 8 is a schematic half sectional view of a sealing device according to the prior art. Fig. 9 is a schematic half sectional view showing a state in use of a sealing device according to the prior art, in which (a) shows no pressure and (b) shows pressure. Fig. 10 is a graph showing the contact surface pressure distribution of a sealing apparatus according to the prior art, where (a) shows low pressure and (b) shows high pressure, respectively.

As a sealing device for rods of hydraulic cylinders, a rib packiing 100 as shown in Fig. 8 has conventionally been used. The lip packing 100 is used as a ring-shaped sealing member mounted in an annular groove formed in the inner circumferential surface of the cylinder.

The lip packing 100 is recessed in the axial direction at the end face of the inner lip 101 protruding in the inner diameter direction, the outer lip 102 protruding in the outer diameter direction, and the high pressure side through which the lip packing 100 receives pressure. An approximately U-shaped annular groove (hereinafter referred to as U-groove) 103 having a fine cross section is provided.

In the lip packing 100, the inner circumferential side and the outer circumferential side are in close contact with the rod outer circumferential surface and the groove bottom surface of the annular groove, respectively, and the contact surface pressure is increased at the portion where the inner circumferential lip 101 and the outer lip 102 are provided. As a result, the hydraulic oil in the hydraulic cylinder is prevented from leaking to the outside.

The material of the lip packing 100 is selected from various things according to a use condition, and typically either one of a black rubber material and a urethane material is selected. The black rubber material is excellent in oil resistance and compression set resistance to compression. On the other hand, a urethane material is made to be excellent in pressure resistance and abrasion resistance.

As the use conditions, urethane materials are selected when the pressure is high and the lubrication is poor. However, since a urethane material generally has high hardness, it may become difficult to attach to a mounting groove. In such a case, a relatively low hardness urethane material (about Hs (JIS A) 90) is selected. In particular, the urethane material used for general lip packing is about Hs94, and the black rubber material is about Hs90.

The lip packing 100 controls the thickness of the oil film passing through the lip packing 100 by the contact surface pressure gradient applied to the contact mating surface (which makes the thickness of the oil film returned to the inside thicker than the thickness of the oil film coming out). Excellent sealing performance. And in the case of the lip packing 100 of the urethane material of low hardness, the deformation amount at the time of pressurization becomes large (refer FIG. 9). In addition, with this, the surface pressure gradient on the lip side may become gentle, and sealing property may fall (refer FIG. 10).

When the material is made low, the pressure resistance of the lip packing 100 is also easily lowered. For example, since the deformation amount at the time of pressurization is large, it may be protruded into the annular gap, and it is easy to cause breakage or the like. Therefore, the shape of the lip packing 100 must be made into the design which considered pressure resistance.

Japanese Patent Publication No. 2008-128377

This invention is made | formed in order to solve said subject of the prior art, The objective is to provide the sealing apparatus which exhibits good sealing property and sells even if hardness is reduced.

In order to achieve the above object, the sealing device in the present invention,

A sealing device mounted on an annular groove formed in one member of a housing having a relatively reciprocating shaft and a shaft hole into which the shaft is inserted, and sealing the annular gap between these two members,

An annular base accommodated in said annular groove,

A first lip installed on one circumferential side of the base and contacting the groove bottom surface of the annular groove;

A second lip installed on the other circumferential side while being at the high pressure side of the base and freely sliding in contact with the main surface of the other member;

A hydraulic groove is opened between the first lip and the second lip on the high pressure side, and receives a pressure acting from the high pressure side to increase the adhesion between the first lip and the second lip.

In the sealing device composed of a rubber-like elastic body having a hardness (Hs) of 90,

The diameter at the tip of the first lip is R1,

The diameter at the tip of the second lip is R2,

The diameter of the groove bottom surface of the annular groove r1,

The diameter of the main surface of the other member is r2

When we did,

R1-R2 | / 2 = (| r1-r2 | / 2) × 1.3 (± 0.03)---(1)

To satisfy

The outer diameter at the bottom of the groove of the hydraulic groove is R3,

The inner diameter at the bottom of the groove of the hydraulic groove is R4,

When we did,

4 ≤ ((R3-R4) / | r1-r2 | -1) × 100 ≤ 8----(2)

To satisfy

The circumferential surface of the other outer circumferential side of the base is a tapered surface that is inclined so as to gradually reduce the radial cross-sectional width of the base toward the low pressure side, and the inclination angle α formed with respect to the axial direction of the tapered surface is

3 ° ≤ α ≤ 7 °----(3)

It is characterized by satisfying.

According to the present invention, the dimensions of R1 to R4 of the lip packing are set so as to satisfy the relational expressions of (1) and (2) above, so that the surface pressure gradient at the lip tip side is kept high, and the contact surface pressure at the lip tip is maintained. Peaks can be generated. Thereby, the surface pressure gradient of contact surface pressure becomes high on the high pressure side, the thickness of the oil film which passes to a high pressure side becomes thin, and the leakage of hydraulic fluid is reduced. Therefore, stable sealing property can be ensured.

Moreover, according to this invention, the dimension of R3, R4, (alpha) of a lip packing is set so that the relationship of said (2) and (3) is set, and the base deformation at the time of pressurization is suppressed, and the low pressure side edge part of the base is suppressed. The other circumferential side edge in Es is out of the annular gap. As a result, damage due to protruding into the annular gap is suppressed, and the pressure resistance is improved.

According to this invention, even if hardness is reduced, it becomes possible to exhibit favorable sealing property.

1 is a schematic half sectional view of a sealing device according to an embodiment of the present invention.
2 is a schematic half sectional view of a sealing device according to an embodiment of the present invention.
3 is a graph showing the contact surface pressure distribution of the sealing apparatus according to the embodiment of the present invention.
4 is a table showing the results of an evaluation test.
5 is a schematic diagram of a test apparatus for the pressure resistance confirmation test.
6 is a schematic diagram of a test apparatus for a product low temperature eccentric traceability confirmation test.
7 is a graph showing the contact surface pressure distribution of the sealing device.
8 is a schematic half sectional view of a sealing device according to the prior art.
9 is a schematic half sectional view showing a state in use of a sealing device according to the prior art.
10 is a graph showing the contact surface pressure distribution of a sealing apparatus according to the prior art.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the form for implementing this invention is demonstrated in detail based on an Example. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention only to those unless specifically stated.

(Example)

1 to 3, a sealing apparatus according to an embodiment of the present invention will be described. 1 is a schematic half sectional view of the sealing device according to the present embodiment. Fig. 2 is a schematic half sectional view of the sealing device according to the present embodiment, in which (a) is the dimension setting of the tightening value of the lip, (b) is the dimension setting of the distortion in the U groove, and (c) is the base. The inclination angle setting of the tapered surface is described respectively. 3 is a graph showing the contact surface pressure distribution of the sealing apparatus according to the present embodiment, in which (a) shows low pressure and (b) shows high pressure, respectively. In addition, in FIG.2 (a), (b), in order to show a dimensional setting clearly, the sealing apparatus is shown in the state which does not produce deformation.

<Outline and Configuration of Sealing Device>

The sealing device according to the present embodiment is a lip packing provided as a sealing device for a rod in a hydraulic cylinder, which is installed to prevent leakage of hydraulic oil in the hydraulic cylinder to the outside in the reciprocating motion of the rod.

As shown in FIG. 1, the lip packing 1 according to the present embodiment is an annular sealing member, which has an annular base 10, an outer circumferential lip 11 as a first lip, and an inner circumference as a second lip. The lip 12 and the U groove 13 to a hydraulic pressure groove are provided. As the material of the lip packing 1, a relatively low hardness urethane rubber having a hardness Hs of 90 is used.

As shown in Fig. 2, the lip packing 1 seals an annular gap between a housing (cylinder) 2 having a shaft hole and a shaft (rod) 3 inserted into the shaft hole. The lip packing 1 has a structure in which the outer circumferential lip 11, the inner circumferential lip 12, and the U groove 13 are formed on one side of the base 10 in the axial direction (high pressure (H) side) region. The lip packing 1 is attached to the annular groove 20 formed in the inner peripheral surface of the shaft hole of the housing 2.

The base 10 has a structure in which the outer lip 11 and the inner lip 12 are supported on the high pressure H side. The inner circumferential surface (main circumferential side on the other circumferential side) 14 of the base 10 is a tapered surface that is inclined so that the radial cross-sectional width of the base 10 gradually decreases toward the low pressure L side. As a result, the inner circumferential edge at the low pressure side cross section of the base 10 is configured to be out of the annular gap.

The outer lip 11 has a structure that protrudes from the outer circumferential side of the base 10 in the axial direction and the outer diameter direction, and the lip tip protrudes in the outer diameter direction. In the outer lip 11, the diameter of the lip tip 11a is set larger than the diameter of the groove bottom surface 21 of the annular groove 20, and is annular at the highest surface pressure in the outer peripheral side region of the lip packing 1. In contact with the groove bottom surface 21 of the groove (20).

The inner lip 12 has a structure that protrudes from the inner circumferential side of the base 10 in the axial direction and the inner diameter direction, and the lip tip protrudes in the inner diameter direction. The inner lip 12 has a diameter of the lip tip 12a set smaller than the diameter of the outer circumferential surface 30 of the shaft 3, and the shaft 3 at the highest surface pressure in the region on the inner circumferential side of the lip packing 1. The outer circumferential surface 30 of the slide freely contact.

The U groove 13 is annularly formed along the outer circumference of the base 10, and is open toward the high pressure H side between the outer circumferential lip 11 and the inner circumferential lip 12. The U groove 13 supports the pressure (hydraulic pressure) p acting from the high pressure H side, so that the outer circumference of the groove bottom surface 21 of the annular groove 20 and the outer circumferential surface 30 of the shaft 3 are supported. It is comprised so that the adhesiveness of the lip 11 and the inner peripheral lip 12 may be improved.

<Dimension of Sealing Device>

Next, various dimension setting in the lip packing 1 which concerns on a present Example is demonstrated.

≪ Tightening value of the lip >>

As shown in Fig. 2 (a), the lip packing 1 according to the present embodiment,

The diameter at the tip of the outer lip 11 is r1 [mm],

The diameter at the tip of the inner lip 12 is r2 [mm],

The diameter of the groove bottom surface 21 of the annular groove 20 is r1 [mm],

The diameter of the outer circumferential surface 30 of the shaft 3 is r2 [mm],

When we did,

R1-R2 | / 2 = (| r1-r2 | / 2) × 1.3 (± 0.03)---(1)

It is configured to satisfy.

That is, the lip cross section width | variety || R1-R2 | / 2 of the lip packing 1 becomes 127 to 133% with respect to the width | variety || r1-r2 | / 2 of the mounting space of the lip packing 1. R1 and R2 are set.

≪ Distortion in the U groove ≫

As shown in Fig. 2 (b), the lip packing 1 according to the present embodiment,

The outer diameter at the groove bottom 13a of the U groove 13 is R3 [mm],

The inner diameter of the groove bottom 13a of the U groove 13 is R4 [mm].

When

4 ≤ ((R3-R4) / | r1-r2 | -1) × 100 ≤ 8---(2)

It is configured to satisfy.

That is, the cross section width ((R3-R4) / 2) of the lip packing 1 at the bottom of the U groove is distorted with respect to the width (| r1-r2 | / 2) of the mounting space of the lip packing 1. R3 and R4 are set to be 4 to 8%.

≪ Inclined angle of the base taper surface ≫

As shown in Figure 2 (c), the lip packing 1 according to the present embodiment,

The inclination angle α formed by the inner circumferential surface 14 of the base 10, which is a tapered surface, with respect to the axial direction,

30 ° ≤ α≤ 70 °----(3)

It is configured to satisfy.

≪ Contact surface pressure distribution ≫

With reference to FIG. 3, the contact surface pressure distribution of the lip packing 1 which concerns on a present Example is demonstrated. In addition, as a comparative example, the contact surface pressure distribution of the lip packing which concerns on the prior art is shown with the broken line.

Here, the specific dimension setting of the lip packing 1 according to this embodiment which investigated the contact surface pressure distribution is as follows.

Axial Width of Lip Packing (1): 10mm

Outer diameter of base 10: Φ88.7mm

The smallest inner diameter of the base 10 (inner diameter at the bottom of the inner lip 12): Φ 76.5 mm,

Diameter of the lip tip 11a of the outer lip 11: Φ91.2mm

Diameter of the lip tip 12a of the inner lip 12: Φ 74.3 mm

Depth of the U-groove 13: 3.2mm

Width in the axial direction from the axial cross section of the outer lip 11 to the boundary line with the outer circumferential surface of the base 10: 3.9 mm

Width in the axial direction from the axial cross section of the inner circumferential lip 12 to the boundary line with the inner circumferential surface 14 of the base 10: 3.7 mm

Moreover, each dimension of the mounting space of the lip packing 1 is as follows.

Diameter of the outer circumferential surface 3a of the shaft 3: Φ 75mm

Diameter of the groove bottom 31 of the annular groove 20: Φ 88mm

Axial Width of Annular Groove 20: 11mm

As shown in FIG. 3, in the lip packing 1 according to the present embodiment, when the pressure acting from the high pressure H side with respect to the lip packing 1 is relatively low pressure (10 MPa) (FIG. 3 (a)). ), It can be seen that even when the pressure acting from the high pressure (H) side to raise the pressure becomes relatively high pressure (21 MPa) (Fig. 3 (b)), the surface pressure gradient on the lip tip side remains high. As a result, as indicated by the arrow X in the figure, it can be seen that in the lip packing 1 according to the present embodiment, a peak of the contact surface pressure is generated at the lip tip 12a.

This effect is considered to be mainly obtained as the dimensions of R1 to R4 of the lip packing 1 are set so as to satisfy the relational expressions of (1) and (2) above. Due to this effect, the surface pressure gradient of the contact surface pressure becomes high on the high pressure H side, and the thickness of the oil film passing through the high pressure H side (that is, the atmospheric side) becomes thin, and the hydraulic oil leaks to the outside. Is reduced. Therefore, stable sealing property can be ensured.

On the other hand, in the conventional example, it turns out that the surface pressure gradient on a lip tip side is made smooth, and the peak of contact surface pressure like this embodiment is not formed.

Moreover, as shown by the arrow Y in FIG. 3, compared with the conventional example, it turns out that the contact surface pressure of the low pressure L side part of the base 10 is reduced. This effect can be considered to be mainly obtained by setting the dimensions of R3, R4 and α of the lip packing 1 so as to satisfy the relational expressions of (2) and (3) above. As a result, the deformation of the base 10 at the time of pressurization is suppressed and the inner circumferential edge of the low pressure L side end portion of the base 10 is protruded from the annular gap, so that it is protruded into the annular gap. Breakage is suppressed. Therefore, the pressure resistance of the lip packing 1 is improved.

On the other hand, in the conventional example, since the contact surface pressure of the low-pressure side site | part of a base is high, it is easy to cause deformation | transformation at the time of pressurization, and the inner peripheral edge of the low-pressure side edge part of a base becomes easy to protrude into an annular clearance. Therefore, there is a fear of breakage due to protruding into the annular gap.

<Evaluation test>

A lip that does not satisfy any of the relations of (1), (2), and (3) with respect to the performance evaluation of the lip packing according to the embodiment that satisfies the relations of (1), (2), and (3). The packing was evaluated as a comparative example. The results are shown in FIG. 4 is a table showing the results of an evaluation test. Evaluation was made on five items (eccentric harvest, wear, breakage of the bottom of the U groove, protruding, contact surface pressure).

Among the evaluation items, abrasion, bulging, and U-groove damage were determined according to the results of the pressure resistance confirmation test. This test was performed using the test apparatus shown in FIG. 5 is a schematic diagram showing the configuration of a test apparatus used for the pressure resistance confirmation test.

In this test, the two lip packings to be tested are respectively mounted in two annular grooves 201 provided on the inner circumferential surface of the cylinder 200, and the pressurizing port 202 is placed in a sealing space between the two test target products. A predetermined pressure was introduced to reciprocate the rod 203 relative to the cylinder 200. The pressure introduced from the pressurizing port 202 was 21 MPa, and the pressure ON / OFF was switched to 2 seconds / 2.5 seconds. The temperature was 100 ° C., the stroke of the rod 203 was ± 40 mm, the frequency was 1 Hz, and the pressure was applied 100,000 times. 204 is a spacer for adjusting the gap gap.

In addition, the eccentric harvestability of the evaluation items was determined by the result of conducting the product low temperature eccentricity harvest test. This test was performed using the test apparatus shown in FIG. Figure 6 is a schematic diagram showing the configuration of a test apparatus used for the product low temperature eccentric harvest confirmation test.

In this test, the two lip packings to be tested are respectively mounted in two annular grooves 301 provided on the inner circumferential surface of the cylinder 300, and the pressure port 302 is provided in a sealed space between the two test target products. The predetermined pressure was introduced from the rod 303 to eccentrically move the cylinder 300 (in the direction of the arrow in the figure). The pressure introduced from the pressure port 302 is 1 MPa, the frequency is 1 Hz, the temperature is -10 ° C, -15 ° C, -20 ° C, and the amplitude (mm) of ± 0.1, ± 0.2, ± 0.3, ± 0.4, ± 0.5 The test was performed under the conditions, and the leakage of low-temperature hydraulic oil (Mobil Oil MIL-H-5606) was observed.

Here, the structure of each Example and each comparative example is as follows.

Example 1: Lip packings designed to be center values, respectively, for the relations (1) to (3).

Example 2: Lip packings designed to be the lower limit, respectively, for the relations of (1) to (3).

Example 3: Lip packings designed to be the upper limit respectively with respect to the relations (1) to (3).

Comparative Example 1: Lip packing exceeding the lower limit for (1) and designed to be the center value for (2) and (3), respectively.

Comparative Example 2: Lip packing exceeding the upper limit for (1) and designed to be the center value for (2) and (3), respectively.

Comparative Example 3: Lip packing exceeding the lower limit for (2) and designed to be the center value for (1) and (3), respectively.

Comparative Example 4: Lip packing exceeding the upper limit for (2) and designed to be the center value for (1) and (3), respectively.

Comparative Example 5: Lip packing exceeding the lower limit for (3) and designed to be the center value for (1) and (2), respectively.

Comparative Example 6: Lip packing exceeding the upper limit for (3) and designed to be the center value for (1) and (2), respectively.

As shown in the test results of FIG. 4, in Comparative Examples 1 to 6 in which none of the relational expressions of (1) to (3) was satisfied, it was found that a problem occurred somewhere in any one of five evaluation items. On the other hand, in Examples 1-3, the evaluation which satisfy | fills the acceptance criteria as a product was obtained in all five evaluation items. Here, the evaluation criteria in each evaluation item are X when any problem that cannot be used as a product arises, and when a problem does not occur, it is ○, and the result shows particularly excellent performance without problems. When was obtained, it was set to ◎.

With respect to the relation of (1), when the tightening value of the lip packing was smaller than 127% (Comparative Example 1), the result was that the sealability due to the eccentric harvest was lowered (the seal was reduced when eccentric). On the other hand, when the tightening value of the lip packing is larger than 133% (Comparative Example 2), the dents become large, and since the lip is always pushed by a strong force, breakage is likely to occur in the oil film, resulting in increased wear.

Regarding the relational expression of (2), when the distortion of the bottom of the U groove was less than 4% (Comparative Example 3), a crack occurred in the bottom of the U groove. On the other hand, when the distortion is larger than 8% (Comparative Example 4), since the lip is always pushed by a strong force due to the increase of the distortion, breakage of the oil film occurs and wear is increased.

Regarding the relational expression of (3), when the inclination angle of the tapered surface of the lip packing recess was smaller than 3 ° (Comparative Example 5), breakage due to protruding occurred. On the other hand, when the inclination angle of the tapered surface was larger than 7 ° (Comparative Example 6), the surface pressure gradient was gentle and the sealing property was deteriorated.

Here, about the relationship of (3), the change of the surface pressure gradient by the change of the inclination-angle of a taper surface is shown in FIG. 7 is a graph showing the contact surface pressure distribution of the lip packing during pressing, (a) when the inclination angle of the tapered surface is 2 °, (b) is when the inclination angle of the tapered surface is 3 °, ( c) shows the case where the inclination angle of the taper surface is 5 degrees, (d) shows the case where the inclination angle of the taper surface is 7 degrees, and (e) shows the case where the inclination angle of the taper surface is 8 degrees, respectively.

As shown in Fig. 7, the smaller the inclination angle of the tapered surface, the greater the surface pressure of the lip tip. If the surface pressure of the lip tip becomes excessively large, the degradation of the seal durability due to the wear of the lip tip is concerned. On the other hand, as the inclination angle of the tapered surface increases, the surface pressure of the lip tip gradually decreases, and the surface pressure gradient becomes gentle. If the surface pressure gradient becomes too gentle and the surface pressure of the lip tip is lost (Fig. 7 (e)), there is a concern that the sealing property is lowered.

As described above, according to this embodiment, even if the hardness is decreased, good sealing property can be exhibited.

On the other hand, in the above description, the configuration in which the lip packing is a rod sealing device, that is, mounted in an annular groove formed in the cylinder has been described. However, the configuration to which the present invention can be applied is not limited thereto. For example, the lip packing may be suitably applied even when the lip packing is a sealing device for a piston, that is, when the lip packing is mounted in an annular groove formed on the outer periphery of the piston to seal the annular gap between the cylinder and the piston to maintain hydraulic pressure. .

1---Lip Packing
10---Donation
11---Outer lip (first lip)
12---Inner lip (second lip)
13---U groove (Hydraulic groove)
2---Housing
20---Fantasy Home
21---Groove bottom
3---axis
30---Outer surface

Claims (1)

A sealing device mounted on an annular groove formed in one member of a housing having a relatively reciprocating shaft and a shaft hole into which the shaft is inserted, and sealing the annular gap between these two members,
An annular base accommodated in the annular groove,
A first lip installed on one circumferential side of the base and contacting the groove bottom surface of the annular groove;
A second lip installed on the other circumferential side while being on the high pressure side of the base and freely sliding in contact with the main surface of the other member;
A hydraulic groove is opened between the first lip and the second lip on the high pressure side, and receives a pressure acting from the high pressure side to increase the adhesion between the first lip and the second lip.
In the sealing device composed of a rubber-like elastic body having a hardness (Hs) of 90,
The diameter at the tip of the first lip is R1,
The diameter at the tip of the second lip is R2,
The diameter of the groove bottom surface of the annular groove r1,
The diameter of the main surface of the other member is r2
When we did,
R1-R2 / 2 = (r1-r2 / 2) x 1.3 (± 0.03)
To satisfy
The outer diameter at the bottom of the groove of the hydraulic groove is R3,
The inner diameter at the bottom of the groove of the hydraulic groove is R4,
When we did,
4 ≤ ((R3-R4) / | r1-r2 | -1) × 100 ≤ 8
To satisfy
The circumferential surface of the other outer circumferential side of the base is a tapered surface that is inclined so as to gradually reduce the radial cross-sectional width of the base toward the low pressure side, and the inclination angle α formed with respect to the axial direction of the tapered surface is
3 ° ≤ α ≤ 7 °
Sealing device, characterized in that to satisfy.

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