JP7475775B2 - Sliding parts - Google Patents

Description

The present invention relates to sliding parts that rotate relative to one another, such as sliding parts used in shaft sealing devices that seal the rotating shafts of rotating machines in automobiles, general industrial machines, or other sealing fields, or sliding parts used in bearings of machines in automobiles, general industrial machines, or other bearing fields.

Mechanical seals, for example, are shaft sealing devices that prevent leakage of sealed fluids and are equipped with a pair of annular sliding parts that rotate relative to one another and have sliding surfaces that slide against each other. In recent years, there has been a demand for such mechanical seals to reduce the energy lost through sliding for environmental reasons, and when the sliding parts rotate relative to one another, positive pressure is generated to separate the sliding surfaces, and a fluid film is placed between the sliding surfaces to improve lubrication and thereby reduce friction.

In addition, mechanical seals are required to be "sealing" in addition to "lubrication" in order to maintain sealing performance over the long term. For example, the mechanical seal shown in Patent Document 1 has a groove extending radially from the leakage side downstream in the direction of rotation in one sliding part, with one end of the groove opening to the leakage side and the other end closed downstream in the direction of rotation and on the sealed fluid side. With this, when the sliding parts rotate relative to each other, the leakage side fluid is sucked in from one end of the groove and a positive pressure is generated at the other end, so that the leakage side fluid flowing out from the other end between the sliding surfaces improves lubrication and suppresses leakage of the sealed fluid to the leakage side.

Japanese Patent No. 6444492 (pages 8-10, Figure 2)

However, in Patent Document 1, the grooves have approximately the same width, incline toward the downstream side in the direction of rotation, and extend in a long, radial band shape, with the leakage fluid being sucked in from one end of the groove. Therefore, in rotating machines with very high rotation speeds, the desired positive pressure cannot be generated, and there is a risk that sufficient lubrication will not be ensured.

The present invention was made with a focus on these problems, and aims to provide a sliding part that can reliably generate the desired positive pressure between the sliding surfaces at high relative rotation speeds of the sliding parts.

In order to solve the above problems, the sliding component of the present invention comprises:
An annular sliding component disposed at a relative rotational location of a rotary machine,
A band-shaped groove extending at least in the circumferential direction is formed on the sliding surface of the sliding part, and a positive pressure generating portion is provided at its downstream end portion downstream in the direction of rotation, and an opening portion opening to the leakage side along the circumferential direction is formed in at least a part of the groove.
According to this, the groove is formed with an opening that opens widely toward the leakage side along the circumferential direction, and the leakage-side fluid is taken into the groove from the opening, so that even if the relative rotation speed of the sliding parts increases, a large amount of the leakage-side fluid can be taken into the groove from the opening, and a desired positive pressure can be generated between the sliding surfaces. In addition, the positive pressure from the groove during the relative rotation of the sliding parts makes it difficult for the sealed fluid to leak to the leakage side.

The groove may have the opening formed over at least one third of its circumferential length.
This allows the leakage fluid to be sufficiently taken in through the opening, and the positive pressure generating section can reliably generate a high positive pressure between the sliding surfaces.

The positive pressure generating portion may be formed so that its tip tapers toward the downstream side in the direction of rotation.
According to this, since the fluid is converged toward the tip of the positive pressure generating portion, the efficiency of generating positive pressure at the downstream end portion can be improved.

The groove may have a first groove portion in which the opening is formed and extending circumferentially, and a second groove portion in which the positive pressure generating portion is formed, extending radially from the downstream end of the first groove portion and having its end closed.
According to this, since the leaking fluid can be introduced into the sealed fluid side that is farther away from the leaking side, the movement of the sealed fluid towards the leaking side can be suppressed.

The second groove portion may be provided so as to extend downstream in the direction of rotation at an angle relative to the radial direction.
This can improve the efficiency of introducing the leakage fluid into the second groove portion.

The grooves may be provided in a plurality of grooves arranged along a circumferential direction, and a downstream end of one of the grooves and an upstream end of an adjacent groove may be provided so as to overlap each other in the radial direction.
With this, the leakage fluid that flows out from the downstream end of one groove between the sliding surfaces makes it difficult for the sealed fluid to be drawn into the upstream end of the adjacent groove, thereby further suppressing leakage of the sealed fluid.

The groove may be formed symmetrically with respect to a line extending in a radial direction.
This allows use regardless of the relative rotation direction of the sliding parts.

In addition, when the second groove portion of the sliding component according to the present invention is extended in the radial direction, it is sufficient that the second groove portion extends with at least a radial component.

1 is a vertical cross-sectional view showing an example of a mechanical seal according to a first embodiment of the present invention. 2 is a view showing a sliding surface of the stationary seal ring according to the first embodiment of the present invention as viewed from the axial direction. FIG. FIG. 2 is an enlarged view of a main portion of a sliding surface of the stationary seal ring according to the first embodiment of the present invention. 13 is a view showing a sliding surface of a stationary seal ring according to a first modified example of the first embodiment of the present invention, as viewed from the axial direction. FIG. FIG. 11 is a view showing a sliding surface of a stationary seal ring according to a second embodiment of the present invention, as viewed from the axial direction. FIG. 11 is an enlarged view of a main portion of a sliding surface of a stationary seal ring according to a second embodiment of the present invention. FIG. 11 is a view showing a sliding surface of a stationary seal ring according to a third embodiment of the present invention, as viewed from the axial direction. FIG. 11 is a view showing a sliding surface of a stationary seal ring according to a fourth embodiment of the present invention, as viewed from the axial direction. FIG. 11 is an enlarged view of a main portion of a sliding surface of a stationary seal ring according to a fourth embodiment of the present invention. FIG. 13 is a view showing a sliding surface of a stationary seal ring according to a fifth embodiment of the present invention, as viewed from the axial direction. FIG. 13 is an enlarged view of a main portion of a sliding surface of a stationary seal ring according to a fifth embodiment of the present invention. FIG. 13 is a view showing a sliding surface of a stationary seal ring according to a sixth embodiment of the present invention, as viewed from the axial direction. FIG. 13 is an enlarged view of a main portion of a sliding surface of a stationary seal ring according to a sixth embodiment of the present invention. FIG. 13 is a view showing a sliding surface of a stationary seal ring according to a seventh embodiment of the present invention, as viewed from the axial direction. FIG. 13 is a view showing a sliding surface of a stationary seal ring according to an eighth embodiment of the present invention as viewed from the axial direction. FIG. 13 is a view showing a sliding surface of a stationary seal ring according to a ninth embodiment of the present invention as viewed from the axial direction. FIG. 23 is a view showing the sliding surface of the stationary seal ring according to the tenth embodiment of the present invention as viewed from the axial direction. FIG. 23 is a view showing the sliding surface of the stationary seal ring according to the eleventh embodiment of the present invention as viewed from the axial direction. FIG. 23 is a view showing the sliding surface of the stationary seal ring according to the twelfth embodiment of the present invention as viewed from the axial direction.

The following describes the embodiment of the sliding part according to the present invention.

The sliding part according to the first embodiment will be described with reference to Figs. 1 to 3. In this embodiment, the sliding part is a mechanical seal. The outer diameter side of the sliding part constituting the mechanical seal will be described as the sealed liquid side (high pressure side) as the sealed fluid side, and the inner diameter side will be described as the atmosphere side (low pressure side) as the leakage side. For ease of explanation, dots may be added to grooves formed on the sliding surface in the drawings.

The mechanical seal for general industrial machinery shown in FIG. 1 is an inside type that seals the sealed liquid F that is about to leak from the outer diameter side to the inner diameter side of the sliding surface. It is mainly composed of a rotating seal ring 20, which is an annular sliding part that is attached to the rotating shaft 1 via a sleeve 2 in a state that it can rotate integrally with the rotating shaft 1, and a ring-shaped stationary seal ring 10, which is a sliding part that is attached to a seal cover 5 fixed to the housing 4 of the attached device in a non-rotating state and axially movable state. The stationary seal ring 10 is biased in the axial direction by the bellows 7, so that the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide closely against each other. The sliding surface 21 of the rotating seal ring 20 is a flat surface, and this flat surface does not have a recess.

The stationary seal ring 10 and the rotating seal ring 20 are typically formed of a combination of SiC (hard material) or SiC (hard material) and carbon (soft material), but are not limited to this and any sliding material used as a sliding material for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, etc. as sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction sintered SiC consisting of SiC and Si, SiC-TiC, SiC-TiN, etc., and examples of carbon include carbonaceous and graphitic mixtures, resin-molded carbon, sintered carbon, etc. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), composite materials, etc. can also be used.

As shown in FIG. 2, the rotating seal ring 20 slides relative to the stationary seal ring 10 as indicated by the solid arrow, and the sliding surface 11 of the stationary seal ring 10 has a plurality of grooves 14 that are equally spaced along the circumferential direction of the stationary seal ring 10 and are arranged concentrically from the downstream end 14A to the upstream end 14B described below. The portion of the sliding surface 11 other than the grooves 14 is a land 12 that forms a flat end surface.

Next, the groove 14 will be described with reference to Figures 2 and 3. In the following description, unless otherwise specified, the rotating seal ring 20 will be described as rotating counterclockwise relative to the stationary seal ring 10 as shown by the solid arrow in Figure 2. Accordingly, the left side of Figure 3 will be described as the downstream side in the direction of rotation, and the right side of Figure 3 will be described as the upstream side in the direction of rotation. The upstream side in the direction of rotation may be referred to simply as the "upstream side," and the downstream side in the direction of rotation may be referred to simply as the "downstream side."

The groove 14 has an opening 15 that is open to the atmosphere and extends in the circumferential direction, a downstream end 14A that communicates with the opening 15 and acts as a positive pressure generating section formed downstream in the direction of rotation, and an upstream end 14B that communicates with the opening 15 and acts as a negative pressure generating section formed upstream in the direction of rotation, and is shaped like a belt curved in an arc along the circumferential direction when viewed in the axial direction, with the circumferential partition wall being longer than the radial partition wall. The groove 14 is also formed symmetrically with respect to a line S1 that extends in the radial direction.

The groove 14 has a downstream wall portion 14a extending radially and generally perpendicular to the downstream end of the opening 15 and the land 12, a peripheral wall portion 14b extending circumferentially and generally perpendicular to the outer diameter end of the downstream wall portion 14a and the land 12, an upstream wall portion 14c extending radially and generally perpendicular to the upstream end of the peripheral wall portion 14b and generally perpendicular to the upstream end of the opening 15 and the land 12, and a bottom surface perpendicular to the downstream wall portion 14a, the peripheral wall portion 14b, and the upstream wall portion 14c. The downstream wall portion 14a and the downstream end of the peripheral wall portion 14b are disposed at the downstream end 14A, and the upstream wall portion 14c and the upstream end of the peripheral wall portion 14b are disposed at the upstream end 14B.

In addition, the groove 14 has an opening 15 and a peripheral wall portion 14b formed substantially parallel to each other, and the width dimension D2 in the radial direction between the opening 15 and the peripheral wall portion 14b is substantially constant. The width dimension D2 is shorter than the opening dimension D1 of the opening 15 (D1>D2), and the opening dimension D1 is approximately 5 times the width dimension D2. Although the opening 15 is open over the entire length of the inner diameter side extending in the circumferential direction, it is sufficient that at least 1/3 or more, preferably 1/2 or more, of the circumferential length of the wall (in this embodiment, the peripheral wall portion 14b) extending substantially concentrically along the circumferential direction of the groove 14 as viewed from the axial direction is open. The opening dimension and the width dimension may be changed as appropriate as long as the opening dimension is larger than the width dimension. Also, the width dimension D2 of the groove 14 does not have to be constant in the circumferential direction.

The groove 14 is formed so that the depth dimension from the surface of the land 12 to the bottom surface of the groove 14 is 5 μm. The depth dimension of the groove 14 may be changed as appropriate. The bottom surface of the groove 14 is flat and formed parallel to the land 12, but this does not prevent the formation of a fine recess in the flat surface or the formation of the groove 14 at an angle to the land 12.

Next, the operation of the stationary seal ring 10 and the rotating seal ring 20 during relative rotation will be described. First, when the general industrial machine is not in operation and the rotating seal ring 20 is not rotating, a small amount of the sealed liquid F on the outer diameter side of the sliding surfaces 11, 21 enters between the sliding surfaces 11, 21 due to capillary action, and the groove 14 is in a state where the sealed liquid F remaining when the general industrial machine is stopped is mixed with gas that has entered from the inner diameter side of the sliding surfaces 11, 21. Note that since the sealed liquid F has a higher viscosity than gas, only a small amount leaks from the groove 14 to the low pressure side when the general industrial machine is stopped.

When the general industrial machine is stopped and there is almost no sealed liquid F remaining in the groove 14, when the rotating seal ring 20 rotates relative to the stationary seal ring 10 (see solid arrow), as shown in Figure 3, the low-pressure fluid A in the groove 14 moves in the direction of rotation of the rotating seal ring 20 as indicated by the arrow L1, generating dynamic pressure in the downstream end 14A.

As the rotary seal ring 20 rotates, the low-pressure fluid A continues to flow into the downstream end 14A, increasing the pressure in the downstream end 14A and generating a positive pressure, and the low-pressure fluid A flows out from the vicinity of the downstream wall portion 14a to its periphery as shown by the arrow L2. In detail, the low-pressure fluid A, which is guided and moves along the peripheral wall portion 14b, flows out from the downstream wall portion 14a at the downstream end 14A between the sliding surfaces 11 and 21, and in particular, converges toward the corner where the downstream wall portion 14a and the peripheral wall portion 14b are approximately perpendicular, and flows out from this corner between the sliding surfaces 11 and 21. Therefore, the pressure of the low-pressure fluid A flowing out from the corner between the downstream wall portion 14a and the peripheral wall portion 14b is the highest, and the pressure gradually decreases as it moves from this corner toward the inner diameter side of the downstream wall portion 14a or the upstream side of the peripheral wall portion 14b. In addition, since centrifugal force acts on the low-pressure fluid A, it is easy for it to flow along the peripheral wall portion 14b.

As the rotary seal ring 20 rotates, the low-pressure fluid A moves toward the downstream end 14A, generating a positive pressure at the downstream end 14A, generating a negative pressure at the upstream end 14B, and the low-pressure fluid A on the atmospheric side is introduced from the circumferential center of the opening 15 as shown by arrow L3, or from the upstream end 14B of the opening 15 as shown by arrow L4. In addition, since the pressure is highest near the downstream end 14A in the groove 14, most of the low-pressure fluid A near the downstream end 14A flows out between the sliding surfaces 11 and 21, and part of the low-pressure fluid A leaks from the downstream end 14A of the opening 15 to the atmosphere.

In addition, at the upstream end 14B, the negative pressure generated causes the low-pressure fluid A that flows out from the downstream end 14A of the adjacent upstream groove 14 to be introduced from the upstream wall portion 14c side, as shown by arrow L5.

When the sealed liquid F flowing out to the inner diameter side between the sliding surfaces 11 and 21 reaches the downstream end 14A of the groove 14, the sealed liquid F can be pushed back to the outer diameter side by the low-pressure side fluid A flowing out from the downstream end 14A of the groove 14 between the sliding surfaces 11 and 21. When the sealed liquid F between the sliding surfaces 11 and 21 reaches the upstream end 14B of the groove 14, the sealed liquid F can be recovered by the negative pressure generated at the upstream end 14B of the groove 14. In addition, since the sealed liquid F has a higher viscosity and a larger specific gravity than gas and is easily affected by rotation, when it is recovered in the groove 14, it moves along the downstream wall portion 14a or the peripheral wall portion 14b due to the rotational force and centrifugal force. Therefore, the sealed liquid F flowing out to the atmosphere side between the sliding surfaces 11 and 21 can be recovered and reliably returned to the sliding surfaces 11 and 21 from the downstream end 14A together with the low-pressure side fluid A.

As a result of the above, when the stationary seal ring 10 and the rotating seal ring 20 rotate relative to each other, a fluid film of the low-pressure fluid A is formed on the inner diameter side between the sliding surfaces 11 and 21. This allows the sliding surfaces 11 and 21 to be separated from each other, improving lubrication through the fluid film.

In this way, the groove 14 is formed with an opening 15 that opens widely toward the atmosphere along the circumferential direction, and the volume of the opening 15 side of the groove 14 is larger than the volume of the downstream end 14A side that generates positive pressure. Therefore, even if the pressure on the downstream end 14A side of the groove 14 increases when the rotation speed of the rotating shaft 1 is increased, a large amount of low-pressure fluid A on the atmosphere side can be taken into the groove 14 from the opening 15, generating dynamic pressure in the groove 14, and the downstream end 14A can generate high positive pressure between the sliding surfaces 11 and 21. In addition, the negative pressure generated at the upstream end 14B of the groove 14 can actively take in the low-pressure fluid A into the groove 14.

In addition, the groove 14 has an opening 15 formed along the inner diameter side, so that the low-pressure fluid A can be sufficiently taken in through the opening 15, and the downstream end 14A can reliably generate a high positive pressure between the sliding surfaces 11, 21.

In addition, since the groove 14 is formed symmetrically with respect to the line S1, when the rotating seal ring 20 rotates clockwise relative to the stationary seal ring 10 as shown by the dotted arrow in FIG. 2, the low-pressure fluid A moves from the downstream end 14A to the upstream end 14B, generating positive pressure at the upstream end 14B and negative pressure at the downstream end 14A. In other words, it functions in the opposite way to when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 10. Therefore, it can be used regardless of the relative rotation direction between the stationary seal ring 10 and the rotating seal ring 20.

In addition, since multiple grooves 14 are provided along the circumferential direction, it is easy to balance the pressure between the sliding surfaces 11, 21 in the circumferential direction. In this embodiment, the grooves 14 are evenly spaced in the circumferential direction, but they may be unevenly spaced. The number of grooves 14 can also be freely changed.

[Modification]
Next, modified examples of the groove will be described. As shown in Fig. 4, the groove 141 of modified example 1 provided in the stationary seal ring 101 is formed in an arc shape of approximately 350 degrees as viewed from the axial direction, i.e., in a C-shape, and is formed line-symmetrically with respect to a line S2 extending in the radial direction. Similarly to the groove 141, the opening 151 of the groove 141 is formed in an arc shape of approximately 350 degrees as viewed from the axial direction, and a large amount of low-pressure side fluid A can be introduced into the groove 141. In this way, it is sufficient that one or more grooves are formed. Furthermore, when multiple grooves are formed, they may be arranged not only equally but also unequally.

Next, the sliding parts of the second embodiment will be described with reference to Figures 5 and 6. Note that the description of the same configuration as the first embodiment will be omitted.

As shown in Figures 5 and 6, the groove 142 provided in the stationary seal ring 102 has an opening 15, a downstream wall portion 142a extending radially from the downstream end of the opening 15 at an incline toward the downstream side in the direction of rotation, a peripheral wall portion 14b, and an upstream wall portion 14c. The downstream end portion 142A is formed at an acute angle toward the tip, where the downstream wall portion 142a and the peripheral wall portion 14b intersect, so that the corner protrudes toward the downstream side in the direction of rotation and toward the sealed liquid F.

In this way, because the downstream wall portion 142a is inclined toward the downstream side in the rotational direction relative to the radial direction, when the low-pressure fluid A is guided to the downstream wall portion 142a, the low-pressure fluid A near the downstream end portion 142A converges toward the narrow point at the tip of the downstream end portion 142A as shown by arrows L1' and L3', thereby improving the efficiency of positive pressure generation at the downstream end portion 142A.

In addition, the groove 142 is more likely to increase the pressure of the low-pressure fluid A flowing out from the tip of the downstream end 142A, as shown by the arrow L2', than in the first embodiment, making it easier to suppress the movement of the sealed liquid F.

Next, the sliding parts of Example 3 will be described with reference to FIG. 7. Note that the description of the same configuration as Example 2 will be omitted.

As shown in FIG. 7, the groove 143 provided in the stationary seal ring 103 is formed symmetrically with respect to a line S3 extending in the radial direction, and has an opening 15, a downstream wall portion 143a, a peripheral wall portion 14b, and an upstream wall portion 143c that extends in the radial direction from the upstream end of the peripheral wall portion 14b and inclines toward the downstream side in the rotational direction. That is, the upstream end portion 143B formed by the upstream wall portion 143c and the peripheral wall portion 14b is formed at an acute angle toward the tip so that the corner where the upstream wall portion 143c and the peripheral wall portion 14b intersect protrudes toward the upstream side in the rotational direction.

As a result, the groove 143 can improve the efficiency of positive pressure generation by converging the low-pressure fluid A to the downstream end 143A or the upstream end 143B, both when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 103 as shown by the solid arrow in FIG. 7, and when the rotating seal ring 20 rotates clockwise relative to the stationary seal ring 103 as shown by the dotted arrow in FIG. 7. Therefore, it can be used regardless of the relative rotation direction between the stationary seal ring 103 and the rotating seal ring 20.

Next, the sliding parts of Example 4 will be described with reference to Figures 8 and 9. Note that descriptions of the same configuration as in Example 1 will be omitted.

As shown in Figures 8 and 9, the groove 144 provided in the stationary seal ring 104 is composed of a first groove portion 144C having an opening 15 and extending in the circumferential direction, and a second groove portion 144D extending in the radial direction perpendicular to the downstream end of the first groove portion 144C, and is formed in an inverted L shape when viewed from the axial direction.

As shown in FIG. 9, the detailed configuration of groove 144 includes a downstream wall portion 144a extending radially and generally perpendicular to the downstream end of opening 15, an outer diameter side peripheral wall portion 144d extending generally perpendicular to the outer diameter side end of downstream wall portion 144a, an intermediate wall portion 144e extending radially and generally perpendicular to the upstream end of outer diameter side peripheral wall portion 144d, an inner diameter side peripheral wall portion 144b extending circumferentially and generally perpendicular to the inner diameter side end of intermediate wall portion 144e, an upstream wall portion 144c, and a bottom of groove 144. The inner diameter side peripheral wall portion 144b, the upstream side wall portion 144c, and the bottom of the groove 144 form the first groove portion 144C, and the downstream side wall portion 144a, the outer diameter side peripheral wall portion 144d, the intermediate wall portion 144e, and the bottom of the groove 144 form the second groove portion 144D that communicates with the first groove portion 144C.

Returning to FIG. 8, the groove 144 has the opening 15 and the outer diameter side peripheral wall portion 144d formed approximately parallel to each other, and the width dimension D20 in the radial direction between the opening 15 and the outer diameter side peripheral wall portion 144d is approximately constant. Furthermore, the width dimension D20 is approximately twice the width dimension D2 and is shorter than the opening dimension D1 of the opening 15 (D1>D20), and the opening dimension D1 is approximately three times the width dimension D20.

In addition, since the inner diameter side peripheral wall portion 144b and the intermediate wall portion 144e of the groove 144 are substantially perpendicular to each other, the angle θ1 between the inner diameter side peripheral wall portion 144b and the intermediate wall portion 144e is substantially 90 degrees (θ1 < 180 degrees).

The second groove portion 144D has an opening dimension D40 (see FIG. 9) between the inner diameter end of the downstream wall portion 144a and the inner diameter end of the intermediate wall portion 144e, i.e., the opening dimension D40 of the second groove portion 144D is shorter than the opening dimension D1 of the opening 15 (D1>D40), and the opening dimension D1 is approximately four times the opening dimension D40.

As shown by the solid arrows in Figures 8 and 9, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 104, the low-pressure fluid A that has moved inside the groove 144 as shown by arrow L1 flows into the corner between the downstream wall portion 144a and the outer diameter side peripheral wall portion 144d as shown by arrow L10, and the low-pressure fluid A flows out from the corner between the sliding surfaces 11 and 21 as shown by arrow L20.

Furthermore, in the second groove portion 144D, in addition to the centrifugal force, dynamic pressure is generated as the low-pressure fluid A flows out from the corner between the downstream wall portion 144a and the outer diameter side peripheral wall portion 144d between the sliding surfaces 11, 21, so that the low-pressure fluid A is introduced as shown by arrow L30 at the opening 15 closest to the downstream end of the first groove portion 144C, i.e., the downstream end of the opening 15.

As a result, a large amount of low-pressure fluid A can be introduced into the corner between the downstream wall portion 144a and the outer diameter side peripheral wall portion 144d, and a positive pressure can be generated on the sealed fluid side separated from the atmosphere side, so that the sealed liquid F between the sliding surfaces 11, 21 can be returned to the sealed liquid side on the outer diameter side, and the movement of the sealed liquid F to the atmosphere side can be suppressed, effectively suppressing the leakage of the sealed liquid F to the atmosphere side.

Next, the sliding parts according to the fifth embodiment will be described with reference to Figures 10 and 11. Note that the description of the same configuration as the fourth embodiment will be omitted.

As shown in Figures 10 and 11, the groove 145 provided in the stationary seal ring 105 is composed of a first groove portion 145C and a second groove portion 145D that extends radially from the downstream end of the first groove portion 145C and inclines toward the downstream side in the rotational direction, and is formed in a V-shape when viewed from the axial direction.

11, the groove 145 includes a downstream wall portion 145a extending from the downstream end of the opening 15 in the outer diameter direction at an inclination toward the downstream side in the rotation direction, an outer diameter side peripheral wall portion 145d extending from the outer diameter side end of the downstream wall portion 145a in the circumferential direction, an intermediate wall portion 145e connecting the upstream end of the outer diameter side peripheral wall portion 145d and the inner diameter side peripheral wall portion 145b, an inner diameter side peripheral wall portion 145b, an upstream wall portion 145c, and a bottom portion of the groove 145. The inner diameter side peripheral wall portion 145b, the upstream wall portion 145c, and the bottom portion of the groove 145 constitute a first groove portion 145C, and the downstream wall portion 145a, the outer diameter side peripheral wall portion 145d, the intermediate wall portion 145e, and the bottom portion of the groove 144 constitute a second groove portion 145D communicating with the first groove portion 145C. Additionally, the downstream end of the second groove 145D is formed such that the corner where the downstream wall 145a and the outer diameter side peripheral wall 145d intersect is an acute angle facing downstream in the direction of rotation.

Returning to FIG. 10, the groove 145 has the opening 15 and the outer diameter side peripheral wall portion 145d formed substantially parallel to each other, and the width dimension D21 in the radial direction between the opening 15 and the outer diameter side peripheral wall portion 145d is substantially constant. Furthermore, the width dimension D21 is approximately twice the width dimension D2 and is shorter than the opening dimension D1 of the opening 15 (D1>D21), and the opening dimension D1 is approximately twice the width dimension D20.

In addition, the angle θ2 between the inner diameter side peripheral wall portion 145b and the intermediate wall portion 145e of the groove 145 is approximately 160 degrees (θ2 < 180 degrees).

The second groove portion 145D has an opening dimension D41 between the inner diameter end of the downstream wall portion 145a and the inner diameter end of the intermediate wall portion 145e, i.e., the opening dimension D41 of the second groove portion 145D is shorter than the opening dimension D1 (D1>D41), and the opening dimension D1 is approximately twice the opening dimension D41.

In this way, since the second groove portion 145D extends in the radial direction while inclining toward the downstream side in the rotation direction, the generation of turbulence near the communication portion between the first groove portion 145C and the second groove portion 145D is suppressed, and the low-pressure side fluid A can be smoothly introduced into the second groove portion 145D as shown by arrows L11 and L31. In addition, since the corner portion formed by the outer diameter side peripheral wall portion 145d and the intermediate wall portion 145e in the second groove portion 145D is formed at an obtuse angle of about 160 degrees, the low-pressure side fluid A is prevented from stagnation at the corner portion between the outer diameter side peripheral wall portion 145d and the intermediate wall portion 145e, and the low-pressure side fluid A can be smoothly moved into the corner portion where the downstream side wall portion 145a and the outer diameter side peripheral wall portion 145d intersect as shown by arrow L12. In addition, since the low-pressure side fluid A is converged at the corner portion where the downstream side wall portion 145a and the outer diameter side peripheral wall portion 145d intersect, a positive pressure can be efficiently generated.

In addition, the groove 145 is more likely to increase the pressure of the low-pressure fluid A flowing out from the tip of the corner between the downstream wall portion 145a and the outer diameter side peripheral wall portion 145d as shown by the arrow L21 than in the fourth embodiment, and is therefore more likely to suppress the movement of the sealed liquid F to the atmosphere. The inner diameter side peripheral wall portion 145b and the intermediate wall portion 145e may be formed to form a continuous arc shape.

Next, the sliding parts of Example 6 will be described with reference to Figures 12 and 13. Note that descriptions of the same configuration as Example 5 will be omitted.

As shown in Figures 12 and 13, the groove 146 provided in the stationary seal ring 106 is composed of a first groove portion 146C and a second groove portion 146D. The second groove portion 146D has an inclined portion 14D that is inclined toward the downstream side of the rotation direction from the downstream end of the first groove portion 146C and extends radially, and an extended portion 14E that is circumferentially extended toward the downstream side of the rotation direction from the outer diameter end of the inclined portion 14D. The second groove portion 146D is formed in an inverted V shape when viewed from the axial direction.

The extension portion 14E has a downstream end portion 146A that is an acute angle formed toward the downstream side in the direction of rotation, and on its inner diameter side, the upstream side including the upstream end portion 146B of the first groove portion 146C of the adjacent groove 146 is arranged across the land 12, and overlaps in the radial direction.

As a result, the second groove portion 146D prevents the sealed liquid F from moving toward the atmosphere, thereby preventing the sealed liquid F from being introduced into the upstream end portion 146B of the first groove portion 146C.

Next, the sliding parts of Example 7 will be described with reference to FIG. 14. Note that the description of the same configuration as Example 4 will be omitted.

As shown in FIG. 14, the groove 147 provided in the stationary seal ring 107 is composed of a first groove portion 147C having an opening 15 and extending in the circumferential direction, a second groove portion 147D extending linearly from the downstream end of the first groove portion 147C at an incline in the radial direction, and a second groove portion 147D' extending linearly from the upstream end of the first groove portion 147C at an incline in the radial direction, and is formed in an Ω shape when viewed from the axial direction.

The second groove portion 147D has an inner diameter side corner 147A that is formed at an acute angle toward the downstream side in the direction of rotation, and the second groove portion 147D' has an inner diameter side corner 147B that is formed at an acute angle toward the upstream side in the direction of rotation. In other words, the groove 147 is formed symmetrically with respect to the line S4.

As shown by the solid arrows in FIG. 14, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 107, the low-pressure fluid A in the second grooves 147D, 147D' and the first grooves 147C converges at the corners 147A and flows out between the sliding surfaces 11, 21.

On the other hand, as shown by the dotted arrow in Figure 14, when the rotating seal ring 20 rotates relative to the stationary seal ring 107 in the clockwise direction on the page, the low-pressure fluid A in the second groove portion 147D, 147D' and the first groove portion 147C converges at the corner portion 147B and flows out between the sliding surfaces 11, 21.

In this way, the groove 147 is formed symmetrically with respect to the line S4, so it can be used regardless of the relative rotation direction between the stationary seal ring 10 and the rotating seal ring 20.

Next, the sliding parts according to Example 8 will be described with reference to FIG. 15. Note that descriptions of the same configuration as in Example 8 will be omitted.

As shown in FIG. 15, the groove 148 provided in the stationary seal ring 108 is composed of a first groove portion 148C, a second groove portion 148D, and a second groove portion 148D', and is formed in an Ω shape when viewed in the axial direction.

The second groove portion 148D has an inner corner 148A that is acutely angled toward the downstream side in the direction of rotation, and the second groove portion 148D' has an outer corner 148B that is acutely angled toward the upstream side in the direction of rotation. That is, the corners 148A and 148B are formed on the diagonal line of the groove 148. In addition, the length dimension D3 of the longest part of the second groove portion 148D is longer than the length dimension D3' of the longest part of the second groove portion 148D' (D3>D3').

As shown by the solid arrow in FIG. 15, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 108, the low-pressure side fluid A in the second grooves 148D, 148D' and the first groove 148C converges at the corner 148A and flows out between the sliding surfaces 11, 21. The longest part of the second groove 148D' is longer than the length dimension D3', and the corner 148A is positioned on the outer diameter side of the corner 148B, so that the low-pressure side fluid A can be easily discharged from the corner 148A to the sealed liquid F side and the sealed liquid F can be made difficult to be sucked in from the corner 148B.

Next, the sliding parts of Example 9 will be described with reference to FIG. 16. Note that the description of the same configuration as Example 6 will be omitted.

As shown in FIG. 16, the groove 149 provided in the stationary seal ring 109 is composed of a first groove portion 149C and a second groove portion 149D. The second groove portion 149D has an inclined portion 14D that is inclined from the downstream end of the first groove portion 149C toward the downstream side in the rotational direction and extends radially, and an extension portion 14E that is circumferentially extended from the outer diameter end of the inclined portion 14D toward the downstream side in the rotational direction, and the second groove portion 149D is formed in an inverted V shape when viewed from the axial direction. In addition, the extension portion 14E of this embodiment is formed narrower than the extension portion 14E of the sixth embodiment, making it easier to generate positive pressure.

The specific dynamic pressure generating mechanism 30 is formed on the outer diameter side of the stationary seal ring 109. The specific dynamic pressure generating mechanism 30 is composed of a plurality of liquid guide grooves 31 that communicate with the sealed liquid side, an annular communicating groove 32 that extends to communicate the inner diameter side end of each liquid guide groove 31, and a Rayleigh step 33 that extends circumferentially concentrically with the stationary seal ring 109 from a position on the outer diameter side of the communicating groove 32 in the liquid guide groove 31 toward the downstream side. The liquid guide groove 31 and the communicating groove 32 are formed 100 μm deeper than the depth dimension of the groove 149, and the Rayleigh step 33 is formed to have the same depth dimension of 5 μm as the groove 149.

When the general industrial machine is not in operation and the rotating seal ring 20 is not rotating, the sealed liquid F enters the specific dynamic pressure generating mechanism 30. Also, as shown by the solid arrow in FIG. 16, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 109, the sealed liquid F moves from the liquid guide groove portion 31 to the Rayleigh step 33 side, generating dynamic pressure in the Rayleigh step 33. Especially during low-speed rotation, the sealed liquid F that flows out from the downstream end portion 33A of the Rayleigh step 33 between the sliding surfaces 11 and 21 forms a liquid film, improving lubrication. Also, since the liquid guide groove portion 31 and the communicating groove portion 32 are deep grooves, a large amount of the sealed liquid F can be retained, and poor lubrication between the sliding surfaces 11 and 21 during low-speed rotation can be avoided.

Next, the sliding parts of Example 10 will be described with reference to FIG. 17. Note that the description of the same configuration as Example 9 will be omitted.

As shown in FIG. 17, the groove 150 provided in the stationary seal ring 110 is composed of a first groove portion 150C, a downstream second groove portion 150D, and an upstream second groove portion 150D', and is formed in an Ω shape when viewed from the axial direction.

A specific dynamic pressure generating mechanism 30' is formed on the outer diameter side of the stationary seal ring 110. The specific dynamic pressure generating mechanism 30' is composed of an inverse Rayleigh step 34 that extends circumferentially concentrically with the stationary seal ring 109 from a specific liquid guide groove portion 31 toward the upstream side. This allows dynamic pressure to be generated by the Rayleigh step 33 and the inverse Rayleigh step 34 regardless of the relative rotational direction between the stationary seal ring 110 and the rotating seal ring 20.

In this embodiment 10, the Rayleigh step 33 and the inverse Rayleigh step 34 have been illustrated as having the same depth dimension, but they may be formed to different depth dimensions. In addition, the circumferential length and radial width of the two may be the same or different.

The number of specific dynamic pressure generating mechanisms may be freely changed. The specific dynamic pressure generating mechanisms may also be dimples that are concave and circular when viewed from the axial direction.

Next, the sliding part according to the eleventh embodiment will be described with reference to FIG. 18. Note that the description of the same configuration as that of the tenth embodiment will be omitted. Note that, for the sake of convenience, the enlarged portion of FIG. 18 shows only the groove 152, and does not show the specific dynamic pressure generating mechanism 30'.

As shown in FIG. 18, the groove 152 provided in the stationary seal ring 111 is composed of a first groove portion 152C, a downstream second groove portion 152D, and an upstream second groove portion 152D', and is formed in a substantially Ω-shape when viewed from the axial direction. The second groove portion 152D has an inclined portion 15D extending radially from the downstream end of the first groove portion 152C at an inclination toward the downstream side in the rotation direction, and an extension portion 15E extending circumferentially from the outer diameter end of the inclined portion 15D downstream in the rotation direction, and the second groove portion 152D is formed in an inverted V-shape when viewed from the axial direction. The second groove portion 152D' has an inclined portion 15D' extending radially from the upstream end of the first groove portion 152C at an inclination toward the upstream side in the rotation direction, and an extension portion 15E' extending circumferentially from the outer diameter end of the inclined portion 15D' upstream in the rotation direction. The inclined portions 15D and 15D' extend from the inner diameter side toward the outer diameter side, slanting away from each other when viewed from the axial direction, and the extended portions 15E and 15E' extend in the circumferential direction from the outer diameter side.

As shown by the solid arrow in FIG. 18, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 111, the inclined portion 15D is inclined, so that the low-pressure fluid A moves along the two side walls 152a that make up the inclined portion 15D, and the low-pressure fluid A can be smoothly introduced into the second groove portion 152D. In addition, the extension portion 15E in the second groove portion 152D has a smaller flow path cross section than the first groove portion 152C, so a high positive pressure can be generated in the extension portion 15E.

In addition, as shown by the dotted arrow in FIG. 18, when the rotating seal ring 20 rotates relative to the stationary seal ring 111 in the clockwise direction on the page, the inclined portion 15D' is inclined, so that the low-pressure side fluid A moves along the two side wall portions 152c that make up the inclined portion 15D', and the low-pressure side fluid A can be smoothly introduced into the second groove portion 152D'. In addition, the extension portion 15E' in the second groove portion 152D' has a smaller flow passage cross section than the first groove portion 152C, so a high positive pressure can be generated in the extension portion 15E'.

Next, the sliding parts of Example 12 will be described with reference to FIG. 19. Note that descriptions of the same configuration as Example 10 will be omitted.

As shown in FIG. 19, the mechanical seal of this embodiment 12 is an outside type that seals the sealed liquid F that is trying to leak from the inner diameter side to the outer diameter side of the sliding surface, and the groove 153 provided in the stationary seal ring 112 is composed of a first groove portion 153C having an opening 15 that opens to the outer diameter side, a downstream second groove portion 153D, and an upstream second groove portion 153D', and is formed in an Ω shape when viewed from the axial direction.

The specific dynamic pressure generating mechanism 40 is formed on the inner diameter side of the stationary seal ring 112. The specific dynamic pressure generating mechanism 40 is composed of a plurality of liquid guide grooves 41 that communicate with the sealed liquid side, an annular communicating groove 42 that extends to communicate with the outer diameter side end of each liquid guide groove 41, a Rayleigh step 43 that extends circumferentially concentric with the stationary seal ring 112 from a position on the inner diameter side of the communicating groove 42 in the liquid guide groove 41 toward the downstream side, and a reverse Rayleigh step 44 that extends circumferentially concentric with the stationary seal ring 112 from a position on the inner diameter side of the communicating groove 42 in the liquid guide groove 41 toward the upstream side. This allows dynamic pressure to be generated by the Rayleigh step 43 and the reverse Rayleigh step 44 regardless of the relative rotation direction between the stationary seal ring 112 and the rotating seal ring 20.

In this way, the sliding part of the present invention may be an outside-type sliding part that seals the sealed liquid F that is about to leak from the inner diameter side to the outer diameter side of the sliding surface, and even in this case, the groove 153 can generate a high positive pressure between the sliding surfaces 11, 21, and lubrication performance can be maintained. In addition, since the second groove portions 153D, 153D' are formed on both circumferential sides of the groove 153, it can be used without being limited to the relative rotation direction between the stationary seal ring 112 and the rotating seal ring 20.

In addition, in Example 12, the inside-type sliding parts in Examples 10 and 11 are exemplified as outside-type sliding parts, but the inside-type sliding parts in Examples 1 to 9 may be exemplified as outside-type sliding parts.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

For example, in the above embodiment, a mechanical seal for general industrial machinery is used as an example of the sliding part, but other mechanical seals for automobiles, water pumps, etc. may also be used. Furthermore, the sliding part is not limited to a mechanical seal, and may be a sliding bearing or other sliding part other than a mechanical seal.

In addition, in the above embodiment, an example was described in which the grooves were provided only in the stationary seal ring, but the grooves may be provided only in the rotating seal ring 20, or may be provided in both the stationary seal ring and the rotating seal ring.

In the above embodiment, a sliding part is provided with multiple grooves of the same shape, but multiple grooves of different shapes may be provided. The spacing and number of grooves can be changed as appropriate.

In addition, although the sealed fluid side has been described as the high pressure side and the leakage side as the low pressure side, the sealed fluid side may be the low pressure side and the leakage side may be the high pressure side, or the sealed fluid side and the leakage side may be at approximately the same pressure.

In addition, in the above-mentioned Examples 4 to 11, the circumferential length dimension of the first groove portion is longer than the radial length dimension of the second groove portion, but the first groove portion may be formed to have the same dimension as the second groove portion or shorter than the second groove portion.

10: Stationary seal ring 11: Sliding surface 14: Groove 14A: Downstream end (positive pressure generating portion)
14B upstream end portion 14D inclined portion 14E extension portion 15 opening 20 rotating seal ring 21 sliding surface 30, 30' specific dynamic pressure generating mechanism 101 to 110 stationary seal ring 141 to 144 groove 144C first groove portion 144D second groove portion 145 groove 145C first groove portion 145D second groove portion 146 groove 146C first groove portion 146D second groove portion 147 groove 147C first groove portion 147D second groove portion 147D' second groove portion 148 groove 148C first groove portion 148D, 148D' second groove portion 148D' second groove portion 149 groove 149C first groove portion 149D second groove portion 150 groove 150C first groove portion 150D, 150D' second groove portion 151 opening 153 Groove 153C First groove portion 153D, 150D' Second groove portion A Low pressure side fluid F Sealed liquid

Claims (6)

An annular sliding component disposed at a relative rotational location of a rotary machine,
a band-shaped groove extending at least in a circumferential direction is formed on a sliding surface of the sliding element, the band-shaped groove having a positive pressure generating portion at a downstream end portion on a downstream side in a relative rotation direction, and an opening portion opening to a leakage side along the circumferential direction is formed in at least a part of the groove,
The opening dimension of the opening is longer than the width dimension of the groove in the radial direction,
the groove has a peripheral wall portion extending in a circumferential direction on a sealed fluid side, and an upstream wall portion extending from the peripheral wall portion to the opening portion on an upstream side in a relative rotation direction,
the positive pressure generating portion is a wall portion extending from the peripheral wall portion to the opening, and is formed so as to be inclined from the peripheral wall portion to the opening toward the upstream side in the relative rotation direction and to be tapered toward the downstream side in the relative rotation direction,
The upstream wall portion is a sliding component that is inclined from the peripheral wall portion to the opening toward the orthogonal or downstream side in the relative rotation direction. The sliding component according to claim 1, wherein the groove has the opening formed over at least 1/3 of its circumferential length. An annular sliding component disposed at a relative rotational location of a rotary machine,
a band-shaped groove extending at least in a circumferential direction is formed on a sliding surface of the sliding element, the band-shaped groove having a positive pressure generating portion at a downstream end portion on a downstream side in a relative rotation direction, and an opening portion opening to a leakage side along the circumferential direction is formed in at least a part of the groove,
The groove has a first groove portion in which the opening is formed and extending in a circumferential direction, and a second groove portion extending from the first groove portion toward the opposite side to the leakage side , one end of the second groove portion is connected to the downstream end of the first groove portion and the other end of the second groove portion is closed, and the positive pressure generating portion is formed in the sliding component. The sliding component according to claim 3, wherein the second groove portion is inclined with respect to the radial direction and extends downstream in the relative rotation direction. The sliding component according to any one of claims 1 to 4, wherein a plurality of the grooves are provided along the circumferential direction, and the downstream end of one of the grooves and the upstream end of the adjacent groove are provided so as to overlap in the radial direction. 5. The sliding component according to claim 1, wherein the groove is formed symmetrically with respect to a line extending in a radial direction.

Images