sliding member

Abstract

To provide a sliding member capable of reducing sliding torque, maintaining sealing function, and achieving miniaturization. In a pair of sliding members that slide against each other, at least one of the sliding surfaces is provided with: a negative pressure generating mechanism that is isolated from the leakage side by a mesa portion on the leakage side; and a mesa portion provided in the negative pressure generating mechanism, the mesa portion provided in the negative pressure generating mechanism being an island-shaped mesa portion surrounded by the negative pressure generating mechanism, the island-shaped mesa portion further being provided with a bridge portion extending toward the mesa portion on the sealed fluid side.

Description

[0001] This application is a divisional application of the patent application with application number 201980059152.X (international application number PCT / JP2019 / 038155) filed on September 27, 2019, and with the title of “Sliding member”. TECHNICAL FIELD

[0002] The present application relates to a sliding member, for example, suitable for a mechanical seal, a bearing, other sliding parts. In particular, it relates to a sliding member such as a seal ring or a bearing, which requires reduction of friction on a sliding surface and prevention of leakage of fluid from the sliding surface. BACKGROUND

[0003] In a mechanical seal, which is an example of a sliding member, in order to maintain the sealing property for a long period of time, there is a technique that takes into account both “sealing” and “lubrication”, which are opposite conditions. For example, in a pair of sliding members that slide against each other, there is known a sliding member in which a positive pressure generating groove is provided on the sealed fluid side of one of the sliding surfaces and a negative pressure generating groove is provided on the leakage side, the positive pressure generating groove and the negative pressure generating groove are respectively communicated with the sealed fluid side, and the sealed fluid side is isolated from the leakage side by the sealing surface (for example, refer to Patent Literature 1).

[0004] If the sliding member of the above structure is slid against each other, the sliding surface is expanded by the positive pressure generated by the positive pressure generating mechanism provided on the sealed fluid side, and becomes a fluid lubrication state in which a liquid film exists on the sliding surface, whereby the sliding torque can be reduced. Also, the suction of fluid from the leakage side to the sliding surface can be generated by the suction action of the negative pressure generated by the negative pressure generating mechanism provided on the leakage side, whereby the leakage amount can be extremely small.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: International Publication Bulletin WO2012 / 046749 SUMMARY OF THE INVENTION

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, in the above technique, the positive pressure generating groove is required to be provided on the sealed fluid side of the sliding surface and the negative pressure generating groove is required to be provided on the leakage side, and there is a problem that this can cause the sliding surface assembly to be large-sized.

[0010] An object of the present application is to provide a sliding member that can reduce the sliding torque, can maintain the sealing function, and can be downsized.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] To solve the problem, a sliding member according to the present application is a pair of sliding members that slide against each other via sliding surfaces, characterized in that

[0013] At least one of the sliding surfaces has a negative pressure generating mechanism that is isolated from the leakage side by a mesa portion on the leakage side, and the mesa portion is provided in the negative pressure generating mechanism.

[0014] According to this feature, an air pocket is generated in the negative pressure generating mechanism due to a pressure drop, and the inside of the air pocket is filled with a gas having low viscosity by vaporization of a liquid, so that the sliding torque of the sliding members can be reduced. Furthermore, a positive pressure is generated by the wedge effect of the mesa portion provided in the negative pressure generating mechanism, the sliding surface can be expanded to cause the fluid to exist on the sliding surface, so that the sliding torque can be further reduced. Moreover, the negative pressure generated by the negative pressure generating mechanism can be used to suck the fluid from the leakage side to the sliding surface to minimize the leakage amount. Without separately providing a positive pressure generating mechanism and a negative pressure generating mechanism as in the conventional technology, the opposite performances of reduction of the sliding torque and improvement of the sealing property can be improved by one negative pressure generating mechanism, so that the size can be reduced.

[0015] The sliding member according to the present application is characterized in that

[0016] The mesa portion provided in the negative pressure generating mechanism is surrounded by the negative pressure generating mechanism to form an island shape.

[0017] According to this feature, the vicinity of the island-shaped mesa portion can be set as a positive pressure region to function as a fluid lubrication function to reduce the sliding torque, and the portion away from the island-shaped mesa portion can be set as a gas phase region based on an air pocket region to achieve the reduction of the sliding torque and the improvement of the sealing property based on the suction effect, so that the opposite performances of reduction of the sliding torque and improvement of the sealing property can be improved by one negative pressure generating mechanism without separately providing a positive pressure generating mechanism and a negative pressure generating mechanism.

[0018] The sliding member according to the present application is characterized in that

[0019] The island-shaped mesa portion further has a bridge portion that extends toward the mesa portion on the sealed fluid side.

[0020] According to this feature, the island-shaped mesa portion provided in the negative pressure generating mechanism and the bridge portion that extends toward the mesa portion on the sealed fluid side efficiently intercept the gas in the negative pressure generating mechanism to generate a positive pressure, so that the gas can exist on the sliding surface to further reduce the sliding torque.

[0021] The sliding member according to the present application is characterized in that

[0022] The negative pressure generating mechanism has a guide groove that faces the mesa portion provided in the negative pressure generating mechanism from the leakage side.

[0023] According to this feature, the fluid in the negative pressure generating mechanism is efficiently guided from the leakage side to the mesa portion provided in the negative pressure generating mechanism through the guide groove, and positive pressure is generated by the mesa portion intercepting the fluid, so the sliding torque can be reduced.

[0024] The sliding member of the present application is characterized in that

[0025] The negative pressure generating mechanism has guide grooves that respectively guide the fluid from the leakage side and the sealed fluid side to the mesa portion provided in the negative pressure generating mechanism.

[0026] According to this feature, the fluid in the negative pressure generating mechanism is efficiently guided from the leakage side and the sealed fluid side to the mesa portion provided in the negative pressure generating mechanism through the guide groove, and positive pressure is generated by the mesa portion intercepting the fluid, so the sliding torque can be reduced.

[0027] The sliding member of the present application is characterized in that

[0028] The negative pressure generating mechanism is composed of the remaining portion of the sliding surface except for the mesa portion.

[0029] According to this feature, the negative pressure generating mechanism is composed of the remaining portion of the sliding surface except for the mesa portion, so the area of the negative pressure generating mechanism can be increased, and the contact area of the gas with low viscosity and the sliding surface can be increased, so the sliding torque can be reduced.

[0030] The sliding member of the present application is characterized in that

[0031] The negative pressure generating mechanism is provided across the average diameter of the sliding surface.

[0032] According to this feature, the negative pressure generating mechanism is provided across both sides of the average diameter of the sliding surface, so the area of the negative pressure generating mechanism can be increased, and the contact area of the gas with low viscosity and the sliding surface can be increased, so the sliding torque can be reduced.

[0033] The sliding member of the present application is characterized in that

[0034] The negative pressure generating mechanism has a fluid introduction groove that communicates with the sealed fluid side, and a groove portion that has an opening portion on the downstream side that communicates with the fluid introduction groove and a dead end portion on the upstream side that is surrounded by the mesa portion.

[0035] According to this feature, the negative pressure generating mechanism can be easily configured.

[0036] The sliding member of the present application is characterized in that

[0037] The deck portion surrounding the end portion is provided with a positive pressure generating mechanism having an opening portion communicating with the fluid introduction groove.

[0038] According to this feature, the deck portion surrounding the end portion is able to generate a positive pressure to maintain a fluid lubrication state even in a case where the fluid lubrication state cannot be sufficiently obtained at the time of start-up or the like, by the positive pressure generating mechanism.

[0039] The sliding member of the present application is characterized in that

[0040] The negative pressure generating mechanism is provided with a plurality of the deck portions.

[0041] According to this feature, the negative pressure generating mechanism and the deck portion can be optimally arranged according to the size of the sliding surface.

[0042] The sliding member of the present application is characterized in that

[0043] The deck portion provided in the negative pressure generating mechanism is provided with a plurality of the deck portions in the negative pressure generating mechanism.

[0044] According to this feature, the deck portion can be optimally arranged in the negative pressure generating mechanism according to the size of the sliding surface. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a longitudinal sectional view showing an example of a mechanical seal provided with the sliding member of the present application.

[0046] Figure 2 is a view in the W-W direction of Fig. Figure 1

[0047] Figure 3 is a view in the W-W direction of Fig. Figure 1

[0048] Figure 4 is a partial enlarged view of the sliding surface of Fig. Figure 3

[0049] Figure 5 is a view in the W-W direction of Fig. Figure 1

[0050] Figure 6 is a view in the W-W direction of Fig. Figure 1

[0051] Figure 7 is a view in the W-W direction of Fig. Figure 1 ​​​​​​

[0052] Figure 8 Therefore Figure 1 The diagram shows the sliding surface of the sliding component in Embodiment 6.

[0053] Figure 9 Therefore Figure 1 The diagram shows the sliding surface of the sliding component in Embodiment 7. Detailed Implementation

[0054] Hereinafter, the manner in which the sliding component is used to implement the present invention will be described with reference to embodiments.

[0055] Example 1

[0056] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described illustratively. Unless otherwise expressly stated, the dimensions, materials, shapes, and relative arrangements of the constituent components described in this embodiment are not intended to limit the scope of the present invention.

[0057] refer to Figure 1 and Figure 2 The sliding member according to Embodiment 1 of the present invention will be described. Furthermore, in Embodiment 1, a mechanical seal, as an example of a sliding member, will be described. In Embodiment 1, the outer peripheral side of the sliding member constituting the mechanical seal will be described as the sealed fluid side (high-pressure fluid side), and the inner peripheral side as the leakage side (low-pressure fluid side).

[0058] Figure 1 This is a longitudinal sectional view showing an example of mechanical seal 1. It is an inner form of a seal that attempts to seal the fluid leaking from the outer periphery of the sliding surface toward the inner periphery. It consists of a rotating side filter cartridge and a fixed side filter cartridge. The rotating side filter cartridge includes: a sleeve 2, which is fitted into the rotating shaft 10; an annular rotating side sealing ring 3, which is one of the sliding components; and a gasket 8, which seals between the sleeve 2 and the rotating side sealing ring 3. The rotating side filter cartridge rotates integrally with the rotating shaft 10.

[0059] The fixed-side filter cartridge includes: a housing 4, which is installed on the outer casing 9; an annular fixed-side sealing ring 5, which is another sliding component; a bellows 7, which seals the fixed-side sealing ring 5 and the housing 4; and a spiral wave spring 6, which applies force to the rotating-side sealing ring 3 via the fixed-side sealing ring 5 and the bellows 7, so that the fixed-side filter cartridge is fixed relative to the outer casing 9 in the direction of rotation and axial direction.

[0060] The mechanical seal 1 with the above structure prevents the sliding surface S of the rotating side sealing ring 3 and the sliding surface S of the fixed side sealing ring 5 from sliding against each other, thus preventing the sealing fluid from flowing out from the outer peripheral side to the inner peripheral side. Additionally, Figure 1The illustration shows a case where the width of the sliding surface S of the rotating side sealing ring 3 is wider than the width of the sliding surface S of the fixed side sealing ring 5, but it is not limited to this case. It is obvious that the invention can also be applied in the opposite case.

[0061] The materials of the rotating side sealing ring 3 and the fixed side sealing ring 5 are selected from silicon carbide (SiC) with excellent wear resistance and carbon with excellent self-lubricating properties. For example, they can be set to be both SiC or a combination of rotating side sealing ring 3 being SiC and fixed side sealing ring 5 being carbon.

[0062] like Figure 2 As shown, the sliding surface S of the fixed-side sealing ring 5 is equipped with a negative pressure generating mechanism 21. The negative pressure generating mechanism 21 is isolated from the leakage side by a leakage-side platform R2. The negative pressure generating mechanism 21 is configured as follows: a fluid inlet groove 22, which communicates with the sealed fluid side; and an annular groove portion 23, having an opening 24 on the downstream side communicating with the fluid inlet groove 22 and a stop portion 25 surrounded by a radial platform portion R3 disposed between the sealed fluid-side platform portion R1 and the leakage-side platform portion R2. Thus, in the negative pressure generating mechanism 21, the upstream stop portion 25 is isolated from both the sealed fluid side and the leakage side by the radial platform portion R3 disposed between the sealed fluid-side platform portion R1 and the leakage-side platform portion R2, while the downstream opening 24 communicates with the sealed fluid side. The depth of the groove portion 23 is 1 μm to 50 μm, and the depth of the fluid inlet groove 22 is 50 μm to 1000 μm, with the fluid inlet groove 22 being deeper than the groove portion 23.

[0063] The negative pressure generating mechanism 21 is disposed on both sides of the average diameter Rm of the sliding surface S of the fixed side sealing ring 5. Wherein, the average diameter Rm = (Ro + Ri) / 2, Ro is the outer diameter of the sliding surface S, and Ri is the inner diameter of the sliding surface S.

[0064] like Figure 2 As shown, a specified number of ( ) are arranged inside the negative pressure generating mechanism 21. Figure 2 In this embodiment, there are six platform surfaces 26. Each platform surface 26 is surrounded by a groove 23 and formed in an island shape. Each platform surface 26 has walls 26a, 26b, and 26c surrounding an internal space 26e, and an opening 26d facing upstream. The internal space 26e communicates with the groove 23 through the opening 26d. The surfaces of the platform surfaces 26a, 26b, and 26c that slide against the opposing sliding surface S (the sliding surface S of the rotating sealing ring 3) are machined to a height approximately the same as the platform surface R1 on the sealed fluid side, the platform surface R2 on the leakage side, and the radial platform surface R3 of the negative pressure generating mechanism 21. Furthermore, the platform surface 26 is rectangular in shape, but it can also be triangular, pentagonal, or other polygonal shapes.

[0065] The negative pressure generating mechanism 21 is composed of the remaining parts of the sliding surface S of the fixed side sealing ring 5, excluding the island-shaped platform surface 26, the sealed fluid side platform surface R1, the leakage side platform surface R2, and the radial platform surface R3.

[0066] If the sliding component on the opposite side (rotating side sealing ring 3) is in the specified direction ( Figure 2 When the mechanism rotates counterclockwise (in the middle direction), the fluid in the groove 23 of the negative pressure generating mechanism 21, due to its viscosity, moves downstream following the movement direction of the rotating sealing ring 3, and is discharged to the sealed fluid side through the downstream fluid inlet groove 22. Therefore, in the negative pressure generating mechanism 21, the fluid discharged from the groove 23 becomes more than the fluid supplied to the groove 23, creating a negative pressure and generating cavitation. The cavitation region is a gas phase generated due to the rupture of the liquid film caused by insufficient liquid flow. In the cavitation region, the sliding torque is mainly based on friction from the low-viscosity gas, which reduces the sliding torque compared to conventional liquid-based fluid lubrication. Here, the negative pressure generating mechanism 21 spans the average diameter Rm of the sliding surface S of the fixed-side sealing ring 5, and is arranged with approximately equal widths on both sides of the average diameter Rm, thereby forming a cavitation region over a wide area from the leakage side of the sliding surface S to the sealed fluid side. Thus, the sliding surface S slides over a wide area with the low-viscosity gas, thereby reducing the sliding torque.

[0067] However, if cavitation occurs in a wider area of ​​the sliding surface S, the entire sliding surface S becomes under negative pressure, causing the fixed-side sealing ring 5 and the rotating-side sealing ring 3 to adhere to each other and come into contact, thus making it impossible to maintain a fluid lubrication state. Therefore, a platform 26 can be arranged inside the negative pressure generating mechanism 21, and positive pressure can be generated by the wedge effect produced by the platform 26, thereby expanding the sliding surface S to achieve a fluid lubrication state. Furthermore, the number of platform 26 is not limited to this embodiment, as long as it can expand the sliding surface S to achieve a fluid lubrication state; the number of platform 26 can be more or less than 6.

[0068] As described above, the sliding component of the present invention achieves the following effects.

[0069] 1. In the cavitation region inside the negative pressure generating mechanism 21, sliding with low-friction gas is the main process, thus reducing sliding torque compared to conventional liquid-based fluid lubrication.

[0070] 2. The fluid in the negative pressure generating mechanism 21 can generate positive pressure based on the wedge effect on the platform surface 26, which expands the sliding surfaces S and keeps the sliding surfaces S in a fluid lubrication state, thus reducing the sliding torque.

[0071] 3. The inside of the negative pressure generating mechanism 21 becomes a negative pressure, so it is able to function as suction that draws in fluid from the sliding surface S toward the leakage side, so it is able to further improve the sealability.

[0072] 4. By providing the mesa portion 26 inside the negative pressure generating mechanism 21, it is able to expand the sliding surface S between the periphery of the mesa portion 26 by generating a positive pressure, so it is able to reduce the sliding torque by setting it to a fluid lubrication state. Also, in the cavitation region inside the negative pressure generating mechanism 21, it is able to mainly slide with gas that has a small friction, so it is able to further reduce the sliding torque. Also, the negative pressure generating mechanism 21 is able to function as suction by the negative pressure inside the negative pressure generating mechanism 21, so it is able to make the leakage extremely small. That is, it is not necessary to separately provide a positive pressure generating mechanism and a negative pressure generating mechanism as in the conventional technology, so it is able to miniaturize the sliding member by being able to realize the reduction of the sliding torque and the improvement of the sealability by one negative pressure generating mechanism 21.

[0073] Example 2

[0074] The sliding member related to Example 2 of the present application is explained. Figure 3 is a view that shows the sliding surface S of the sliding member related to Example 2, and has a guide groove 29, so it is different from Example 1 in this point, but the other structures are the same as Example 1. Hereafter, the same symbols are assigned to the same members as Example 1, and the repeated explanation is omitted.

[0075] As shown in Figure 3 , the sliding surface S of the fixed side seal ring 5 is provided with the negative pressure generating mechanism 21. The negative pressure generating mechanism 21 is configured by a fluid introduction groove 22 that communicates with the sealed fluid side, and a ring-shaped groove portion 23 that has an open portion 24 on the downstream side that communicates with the fluid introduction groove 22, and a dead end portion 25 that is surrounded by the sealed fluid side mesa portion Rl, the leakage side mesa portion R2, and the radial mesa portion R3. Due to this, in the negative pressure generating mechanism 21, the dead end portion 25 on the upstream side is isolated from the sealed fluid side and the leakage side by the radial mesa portion R3 that is provided between the sealed fluid side mesa portion Rl and the leakage side mesa portion R2, and the open portion 24 on the downstream side communicates with the sealed fluid side. The depth of the groove portion 23 is 1 μm to 50 μm, and the fluid introduction groove 22 is 50 μm to 1000 μm, and the fluid introduction groove 22 is formed deeper than the groove portion 23.

[0076] As shown in Figure 3 and Figure 4 , a prescribed number of Figure 3The island-shaped deck portion 26 is provided with a wall portion 26a, 26b, 26c that surrounds an inner space 26e, and an opening portion 26d that opens toward the upstream side. The inner space 26e communicates with the groove portion 23 through the opening portion 26d. The wall portions 26a, 26b, 26c of the deck portion 26 are smooth-surfaced at the same height as the sealing-fluid-side deck portion Rl, the leakage-side deck portion R2, and the radial deck portion R3. The outer shape of the deck portion 26 is rectangular, but can be triangular, polygonal with five or more sides, semicircular, semi-elliptical, or the like.

[0077] A guide groove 29 is provided at the bottom of the negative-pressure generating mechanism 21. The guide groove 29 is formed by providing a plurality of extremely thin grooves that are shallower than the groove portion 23 of the negative-pressure generating mechanism 21. The guide groove 29 is formed by a sealing-fluid-side guide groove 29a that is provided at substantially equal intervals in the circumferential direction from the sealing-fluid-side deck portion Rl toward the central portion (mean diameter Rm) of the sliding surface S, and a leakage-side guide groove 29b that is provided at substantially equal intervals in the circumferential direction from the leakage-side deck portion R2 toward the central portion (mean diameter Rm) of the sliding surface S. The sealing-fluid-side guide groove 29a and the leakage-side guide groove 29b are provided so as to collectively face the opening portion 26d of the deck portion 26.

[0078] The negative-pressure generating mechanism 21 is formed by the sliding surface S of the fixed-side sealing ring 5, excluding the deck portion 26, the sealing-fluid-side deck portion Rl, the leakage-side deck portion R2, and the radial deck portion R3.

[0079] As shown in FIG. 1, the sealing-fluid-side deck portion Rl is formed by the deck portion 26 and the sealing-fluid-side deck portion Rl. The leakage-side deck portion R2 is formed by the deck portion 26 and the leakage-side deck portion R2. The radial deck portion R3 is formed by the deck portion 26 and the radial deck portion R3. Figure 3 Figure 4 As shown in FIG. 1, the sealing-fluid-side deck portion Rl is formed by the deck portion 26 and the sealing-fluid-side deck portion Rl. The leakage-side deck portion R2 is formed by the deck portion 26 and the leakage-side deck portion R2. The radial deck portion R3 is formed by the deck portion 26 and the radial deck portion R3. Figure 3 Figure 4 ​​When the mechanism rotates counterclockwise (in the middle direction), the fluid in the groove 23 of the negative pressure generating mechanism 21, due to its viscosity, flows downstream following the movement direction of the rotating sealing ring 3, and is discharged to the sealed fluid side through the downstream fluid inlet groove 22. Therefore, in the negative pressure generating mechanism 21, the fluid discharged from the groove 23 becomes more than the fluid supplied to the groove 23, creating a negative pressure and generating cavitation. The cavitation region is a gas phase region generated due to the rupture of the liquid film caused by insufficient liquid flow. In the cavitation region, the sliding torque is mainly based on gas friction, which reduces the sliding torque compared to conventional liquid-based fluid lubrication. Here, the negative pressure generating mechanism 21 spans the average diameter Rm of the sliding surface S of the fixed-side sealing ring 5, and is arranged with approximately equal widths on both sides of the average diameter Rm, thereby forming a cavitation region over a wide area from the leakage side of the sliding surface S to the sealed fluid side. Thus, the sliding surface slides with low-viscosity gas over a wide range, thereby reducing the sliding torque.

[0080] However, if cavitation occurs in a wider area of ​​the sliding surface S, the entire sliding surface S becomes under negative pressure, causing the fixed-side sealing ring 5 and the rotating-side sealing ring 3 to adhere to each other and come into contact, making it impossible to maintain fluid lubrication. Therefore, a platform 26 is arranged inside the negative pressure generating mechanism 21. Positive pressure is generated by the wedge-shaped effect of the platform 26, expanding the space between the sliding surfaces S to achieve fluid lubrication. Furthermore, the number of platform 26 is not limited to this embodiment, as long as it can expand the space between the sliding surfaces S to achieve fluid lubrication, and the number of platform 26 can be more or less than 6.

[0081] The cavitation region is primarily a gas phase region, but there is also flow of general liquid within it. This liquid, being heavier than the gas, accumulates at the bottom of the negative pressure generating mechanism 21. Therefore, by providing the guide groove 29 at the bottom of the negative pressure generating mechanism 21, the liquid in the cavitation region can be efficiently collected onto the platform 26 disposed inside the negative pressure generating mechanism 21. Furthermore, the liquid collected at the opening 26d of the platform 26 generates a large positive pressure due to the wedge-shaped effect of the platform 26, thereby expanding the space between the sliding surfaces S to maintain fluid lubrication.

[0082] like Figure 4 As shown, the liquid in the cavitation region is guided through the sealed fluid-side guide groove 29a and the leakage-side guide groove 29b, forming a strip-shaped liquid phase region in the center of the sliding surface S. Furthermore, the liquid phase region is guided to the opening 26d of the platform surface 26 by the rotation of the rotating side sealing ring 3. A large positive pressure is generated based on the wedge effect of the platform surface 26, thereby widening the gap between the sliding surfaces S to maintain the sliding surfaces S in a fluid-lubricated state.

[0083] Further, both sides of the liquid phase region become the gas pocket region, and the sliding torque is mainly based on the friction of the gas having a small viscosity, so the sliding torque can be reduced compared with the conventional fluid lubrication based on a liquid. Moreover, the gas pocket region has become a negative pressure region, so the negative pressure generating mechanism 21 can exert a suction effect of sucking the fluid from the leakage side into the sliding surface S by the negative pressure, thereby reducing the leakage.

[0084] Further, in the present embodiment, the guide groove 29 is composed of the sealed fluid side guide groove 29a and the leakage side guide groove 29b, but can be composed of the sealed fluid side guide groove 29a or the leakage side guide groove 29b.

[0085] As described above, the sliding member of the present application exerts the following effects.

[0086] 1. The negative pressure generating mechanism 21 generates a negative pressure, so that the inside of the negative pressure generating mechanism 21 becomes a gas pocket region, and the sliding torque is mainly based on the friction of the gas in the negative pressure generating mechanism 21, so the sliding torque can be reduced compared with the conventional fluid lubrication based on a liquid.

[0087] 2. The liquid in the gas pocket region is heavier than the gas and is gathered at the bottom of the negative pressure generating mechanism 21, so by providing the guide groove 29 at the bottom of the negative pressure generating mechanism 21, the liquid remaining in the gas pocket region can be efficiently guided to a prescribed position.

[0088] 3. The liquid in the gas pocket region guided to the deck portion 26 by the guide groove 29 generates a positive pressure based on a wedge effect at the deck portion 26, so the sliding surfaces S can be maintained in a fluid lubrication state by extending between the sliding surfaces S.

[0089] 4. The negative pressure generating mechanism 21 becomes a negative pressure region, so the negative pressure generating mechanism 21 can exert a suction effect of sucking the fluid from the leakage side into the sliding surface S by the negative pressure to reduce the leakage, and can further improve the sealing property.

[0090] 5. By providing the deck portion 26 inside the negative pressure generating mechanism 21, a positive pressure can be generated at the periphery of the deck portion 26, so the sliding surfaces S can be maintained in a fluid lubrication state by extending between the sliding surfaces S, so the sliding torque can be reduced. The gas pocket region inside the negative pressure generating mechanism 21 becomes a gas phase region having a small friction, so the sliding torque can be further reduced. The negative pressure generating mechanism 21 exerts a suction effect by the negative pressure inside the negative pressure generating mechanism 21, so the leakage can be made extremely small and the sealing property can be improved. That is, it is not necessary to separately provide a positive pressure generating mechanism and a negative pressure generating mechanism as in the conventional technology, but the reduction of the sliding torque and the improvement of the sealing property can be achieved by one negative pressure generating mechanism 21, so the sliding member can be miniaturized.

[0091] Embodiment 3

[0092] The sliding component according to Embodiment 3 of the present invention will be described. Figure 5 This diagram shows the sliding surface S of the sliding component involved in Embodiment 3. Only the shape of the platform surface 36 and the structure of the guide groove 39 are different from those in Embodiment 2; the other structures are the same as in Embodiment 2. Hereinafter, the same symbols will be used to label the same components as in Embodiment 2, and repeated descriptions will be omitted.

[0093] like Figure 5 As shown, the sliding surface S of the fixed-side sealing ring 5 is equipped with a negative pressure generating mechanism 31. The negative pressure generating mechanism 31 comprises: a fluid inlet groove 32 communicating with the sealed fluid side; and an annular groove portion 33 having an opening 34 communicating with the fluid inlet groove 32 on its downstream side, and a stop portion 35 surrounded by a sealed fluid-side platform R1, a leakage-side platform R2, and a radial platform R3. Thus, in the negative pressure generating mechanism 31, the upstream stop portion 35 is isolated from the sealed fluid side and the leakage side by the radial platform R3 disposed between the sealed fluid-side platform R1 and the leakage-side platform R2, while the downstream opening 34 communicates with the sealed fluid side. The depth of the groove portion 33 is 1 μm to 50 μm, and the fluid inlet groove 32 is 50 μm to 1000 μm deep, with the fluid inlet groove 32 being deeper than the groove portion 33.

[0094] The negative pressure generating mechanism 31 is equipped with a specified number of ( Figure 5 In this embodiment, there are six platform surfaces 36. Each platform surface 36 is generally L-shaped, consisting of an island platform surface 36a and a bridge portion 36b connecting the island platform surface 36a and the platform surface R1 on the sealed fluid side. The internal space 36e, surrounded by the L-shaped platform surface 36 and the platform surface R1 on the sealed fluid side, communicates with the groove portion 33 of the negative pressure generating mechanism 31 via an opening portion 36d opening towards the upstream side of the negative pressure generating mechanism 31. The surfaces of the island platform surface 36a and the bridge portion 36b of the platform surface 36 that slide with the opposite sliding surface S (the sliding surface S of the rotating sealing ring 3) are machined to a smooth height at the same level as the platform surface R1 on the sealed fluid side, the leakage side platform surface R2, and the radial platform surface R3.

[0095] A guide groove 39 is provided at the bottom of the negative pressure generating mechanism 31. The guide groove 39 is a very fine, strip-shaped groove that is shallower than the groove portion 33 of the negative pressure generating mechanism 31, and is provided in a predetermined number at approximately equal intervals along the circumference from the leakage side platform R2 toward the side of the sealed fluid. The guide groove 39 is configured to face the opening 36d of the platform portion 36 as a whole.

[0096] If the sliding component on the opposite side (rotating side sealing ring 3) is in the specified direction ( Figure 5If the rotation direction of the rotating shaft 10 is reversed (counterclockwise direction in the figure), the fluid in the groove portion 33 of the negative pressure generating mechanism 31 moves to the downstream side following the moving direction of the rotating side seal ring 3 due to its viscosity, and is discharged to the sealed fluid side through the fluid introduction groove 32 on the downstream side. Thus, the fluid discharged from the groove portion 33 in the negative pressure generating mechanism 31 becomes more than the fluid supplied to the groove portion 33, and the inside of the negative pressure generating mechanism 31 becomes a negative pressure to generate a cavitation. The cavitation region becomes a gas phase region, and thus the sliding torque is mainly based on the friction of the gas having a small viscosity, and the sliding torque can be reduced compared to the conventional fluid lubrication based on a liquid.

[0097] However, if the cavitation region is formed in a wide area of the sliding surface S, the entire sliding surface S becomes a negative pressure, and the stationary side seal ring 5 and the rotating side seal ring 3 are attracted to each other to come into contact, and thus the fluid lubrication state cannot be maintained. Therefore, the mesa portion 36 is arranged inside the negative pressure generating mechanism 31, and a positive pressure is generated by a wedge effect generated in the mesa portion 36 to expand the sliding surface S to maintain the fluid lubrication state. In addition, the number of the mesa portions 36 is not limited to the present embodiment as long as the sliding surface S can be expanded to be set to the fluid lubrication state, and the number of the mesa portions 36 can be more than six or less than six.

[0098] There is also a flow of a general liquid inside the cavitation region. The liquid is heavier than the gas and is gathered at the bottom of the negative pressure generating mechanism 31, and thus by providing the guide groove 39 at the bottom of the groove portion 33 of the negative pressure generating mechanism 31, the liquid in the cavitation region can be efficiently gathered to the opening portion 36d of the mesa portion 36 arranged inside the negative pressure generating mechanism 31. Furthermore, the liquid gathered to the opening portion 36d of the mesa portion 36 generates a large positive pressure based on the wedge effect of the mesa portion 36, and thus the fluid lubrication state can be maintained.

[0099] In particular, when the rotating shaft 10 rotates at a high speed, the liquid inside the cavitation region is easily affected by the centrifugal force and is easily gathered to the radially outer side of the sliding surface S. Therefore, when the rotating side seal ring 3 rotates at a high speed, by configuring the mesa portion 36 to be a substantially L-shaped extending from the mesa portion R1 on the sealed fluid side (the outer diameter side), the liquid in the cavitation region can be efficiently gathered to the mesa portion 36, and a large positive pressure can be generated based on the wedge effect of the mesa portion 36.

[0100] As described above, the sliding member of Embodiment 3 exerts the following effects.

[0101] 1. The negative pressure generating mechanism 31 generates a negative pressure to set the inside of the negative pressure generating mechanism 31 to a cavitation region, and thus the friction based on the gas is mainly in the negative pressure generating mechanism 31, and thus the sliding torque can be reduced compared to the conventional fluid lubrication based on a liquid.

[0102] 2. When the rotary side seal ring 3 is rotated at high speed, the liquid inside the cavitation region is easily gathered on the sealed fluid side by the centrifugal force, and therefore, by configuring the land portion 36 in a substantially L-shape extending from the land portion Rl on the outer diameter side, the liquid inside the cavitation region can be efficiently gathered to the land portion 36.

[0103] 3. The liquid inside the cavitation region guided to the land portion 36 by the guide groove 39 generates a positive pressure based on the wedge effect at the land portion 36, and therefore, the sliding surface S can be expanded to maintain the sliding surface S in a fluid lubrication state.

[0104] 4. The negative pressure generating mechanism 31 becomes a negative pressure region, and therefore, functions as a suction effect that sucks fluid from the leakage side into the sliding surface S by negative pressure, and therefore, leakage can be reduced, and the sealability can be further improved.

[0105] 5. The negative pressure generating mechanism 31 is formed across both sides of the average diameter Rm of the sliding surface S of the fixed side seal ring 5, and is configured as a land portion 36 in a substantially L-shape extending from the land portion Rl on the sealed fluid side, and therefore, the sealed fluid side of the sliding surface S can be made into a positive pressure region, and can function as a fluid lubrication function to reduce the sliding torque, and the leakage side of the sliding surface S can be made into a gas phase region based on the cavitation region to further reduce the sliding torque. Furthermore, the suction effect can be exerted by the negative pressure inside the negative pressure generating mechanism 31, and therefore, the improvement of the sealability can be achieved. That is, unlike the conventional technology, in which a positive pressure generating mechanism and a negative pressure generating mechanism are separately provided, the reduction of the sliding torque and the improvement of the sealability can be achieved by one negative pressure generating mechanism 31, and therefore, the sliding member can be miniaturized.

[0106] Example 4

[0107] A sliding member according to Example 4 of the present application will be described. Figure 6 is a view showing the sliding surface S of the sliding member according to Example 4, and only the shape of the land portion 46 is different from that of Example 3, and the other structures are the same as those of Example 3. Hereinafter, the same reference numerals are assigned to the same components as those of Example 3, and the repeated description will be omitted.

[0108] As Figure 6As shown, the sliding surface S of the fixed-side sealing ring 5 is equipped with a negative pressure generating mechanism 41. The negative pressure generating mechanism 41 comprises: a fluid inlet groove 42 communicating with the sealed fluid side; and an annular groove portion 43 having an opening 44 communicating with the fluid inlet groove 42 on its downstream side, and a stop portion 45 surrounded by a sealed fluid-side platform R1, a leakage-side platform R2, and a radial platform R3. Thus, in the negative pressure generating mechanism 41, the upstream stop portion 45 is isolated from the sealed fluid side and the leakage side by the radial platform R3 disposed between the sealed fluid-side platform R1 and the leakage-side platform R2, while the downstream opening 44 communicates with the sealed fluid side. The depth of the groove portion 43 is 1 μm to 50 μm, and the fluid inlet groove 42 is 50 μm to 1000 μm deep, with the fluid inlet groove 42 being deeper than the groove portion 43.

[0109] The negative pressure generating mechanism 41 is equipped with a specified number of ( Figure 6 In this embodiment, there are six platform surfaces 46. Each platform surface 46 is arc-shaped, consisting of a pointed, island-shaped platform surface 46a and a bridge portion 46b connecting the platform surface 46a and the platform surface R1 on the sealed fluid side. The platform surface 46 has an internal space 46e surrounded by the platform surface R1 on the sealed fluid side and an opening 46d opening towards the upstream side of the negative pressure generating mechanism 41, communicating with the groove 43 of the negative pressure generating mechanism 41 via the opening 46d. The surfaces of the pointed platform surface 46a and the bridge portion 46b of the platform surface 46 that slide with the opposing sliding surface S (the sliding surface S of the rotating sealing ring 3) are machined to a smooth height at the same height as the platform surface R1 on the sealed fluid side, the platform surface R2 on the leakage side, and the radial platform surface R3 of the negative pressure generating mechanism 41.

[0110] A guide groove 49 is provided at the bottom of the negative pressure generating mechanism 41. The guide groove 49 is a strip-shaped, extremely fine groove that is shallower than the groove portion 43, and a predetermined number of them are arranged circumferentially at approximately equal intervals from the leakage side platform portion R2 toward the sealed fluid side. The guide groove 49 is configured to face the opening 46d of the platform portion 46 as a whole.

[0111] If the sliding component on the opposite side (rotating side sealing ring 3) is in the specified direction ( Figure 6 When the mechanism rotates counterclockwise (in the middle direction), the fluid in the groove 43 of the negative pressure generating mechanism 41 moves in the direction of movement of the rotating sealing ring 3 due to its viscosity, and is discharged to the sealed fluid side through the downstream fluid inlet groove 42. Therefore, in the negative pressure generating mechanism 41, the fluid discharged from the groove 43 becomes more than the fluid supplied to the groove 43, creating a negative pressure and generating cavitation within the negative pressure generating mechanism 41. The cavitation region becomes a gas phase region, so the sliding torque is mainly based on friction of the low-viscosity gas, which reduces the sliding torque compared to conventional liquid-based fluid lubrication.

[0112] However, if cavitation occurs in a wider area of ​​the sliding surface S, the entire sliding surface S becomes under negative pressure, causing the fixed-side sealing ring 5 and the rotating-side sealing ring 3 to adhere to each other and come into contact, thus making it impossible to maintain fluid lubrication. Therefore, a platform 46 is arranged inside the negative pressure generating mechanism 41, generating positive pressure around the platform 46 based on a wedge effect to expand the space between the sliding surfaces S and maintain fluid lubrication. Furthermore, the number of platform 46 is not limited to this embodiment, as long as it can expand the space between the sliding surfaces S to achieve fluid lubrication; the number of platform 46 can be more or less than six.

[0113] The cavitation region is a gas phase region, but there is also flow of ordinary liquid within it. This liquid, being heavier than the gas, accumulates at the bottom of the negative pressure generating mechanism 41. Therefore, by providing the guide groove 49 at the bottom of the negative pressure generating mechanism 41, the liquid in the cavitation region can be efficiently collected into the opening 46d of the platform surface 46 disposed inside the negative pressure generating mechanism 41. Furthermore, the liquid collected at the opening 46d of the platform surface 46 can maintain fluid lubrication by generating a large positive pressure based on the wedge-shaped effect of the platform surface 46.

[0114] The internal space 46e of the platform 46 forms a constricted flow path from the opening 46d on the upstream side toward the downstream side. Therefore, the liquid guided to the cavitation area of ​​the platform 46 can generate greater positive pressure through the throttling effect based on the constricted flow path and the wedge effect based on the platform 46.

[0115] As described above, in addition to the effects of Example 3, the sliding component involved in Example 4 also has the following effects.

[0116] The platform surface 46 is formed into a constricted flow path from the upstream opening 46d toward the downstream side. Therefore, the liquid guided to the cavitation area of ​​the platform surface 46 can generate a greater positive pressure than in Examples 2 and 3 through the pressure boosting effect based on the throttling effect of the constricted flow path and the wedge effect based on the platform surface 46.

[0117] Example 5

[0118] The sliding component according to Embodiment 5 of the present invention will be described. Figure 7 This diagram shows the sliding surface S of the sliding member involved in Embodiment 5. The sliding surface S is provided with multiple negative pressure generating mechanisms 41 as in Embodiment 4, which differs from Embodiment 4 in this respect. Other structures are the same as in Embodiment 4. Hereinafter, the same symbols are used to denote the same components as in Embodiment 4, and repeated descriptions are omitted.

[0119] like Figure 7 As shown, in the sliding surface S of the fixed-side sealing ring 5, a specified number of ( ) are provided in the groove 43. Figure 7The number of the negative pressure generating mechanisms 41 arranged along the circumference direction across the radial land portion R3 is not limited to the embodiment, and can be two or four, five or more than six. Figure 7 The number of the negative pressure generating mechanisms 41 arranged along the circumference direction across the radial land portion R3 is not limited to the embodiment, and can be two or four, five or more than six.

[0120] In the embodiment 5, the negative pressure generating mechanisms 41 provided with the plurality of land portions 46 are arranged along the circumference direction across the radial land portion R3 by three, and therefore the fluid is supplied to the sliding surface S from the fluid introduction grooves 42 at a plurality of positions, and therefore even when the fluid lubrication state is not sufficient in the low speed rotation state at the time of start-up and the like, the lubrication of the sliding surface S is facilitated by the fluid supplied from the fluid introduction grooves 42.

[0121] As described above, the sliding member according to the embodiment 5 has the following effects in addition to the effects of the embodiment 4.

[0122] By providing the plurality of fluid introduction grooves 42, the fluid is supplied to the sliding surface S from the fluid introduction grooves 42 at a plurality of positions in the circumference direction, and therefore even when the fluid lubrication state is not sufficient in the low speed rotation state at the time of start-up and the like, the lubrication of the sliding surface S is facilitated by the fluid supplied from the plurality of fluid introduction grooves 42 in the circumference direction.

[0123] Embodiment 6

[0124] The sliding member according to the embodiment 6 will be described. Figure 8 is a view showing the sliding surface S of the sliding member according to the embodiment 6, and the number of the land portions 46 is different from that of the embodiment 5, and in this respect, the embodiment 6 is different from the embodiment 5, and the other structures are the same as those of the embodiment 5. Hereinafter, the same symbols are attached to the same components as those of the embodiment 5, and the repeated description will be omitted.

[0125] As shown in Figure 8 , the negative pressure generating mechanisms 41 provided with one land portion 46 and the guide groove 49 in the groove portion 43 in the sliding surface S of the stationary side seal ring 5 are arranged along the circumference direction across the radial land portion R3 by a prescribed number (three in the embodiment). Figure 8 The number of the negative pressure generating mechanisms 41 arranged along the circumference direction across the radial land portion R3 is not limited to the embodiment, and can be two or four, five or more than six.

[0126] The flow in the negative pressure generating mechanism 41 can be concentrated in the one land portion 46 provided on the downstream side, and therefore a larger positive pressure can be generated than when a plurality of land portions 46 are provided in one negative pressure generating mechanism 41. This is suitable for a case where a large pressure is attempted to be generated on the sliding surface S by a small sliding member.

[0127] As described above, in addition to the effects of Embodiment 5, the sliding component involved in Embodiment 6 also has the following effects.

[0128] Multiple negative pressure generating mechanisms 41, by providing a platform 46 on the downstream side respectively, can concentrate the flow of fluid in the cavitation area on a platform 46, and generate a large positive pressure through the pressure boosting effect based on the constricted flow path and the wedge effect based on the platform 46.

[0129] Example 7

[0130] The sliding component according to Embodiment 7 of the present invention will be described. Figure 9 This diagram shows the sliding surface S of the sliding member involved in Embodiment 7. A positive pressure generating mechanism 47 is provided within the radial platform R4 of the negative pressure generating mechanism 41, which differs from Embodiment 6. Other structures are the same as in Embodiment 6. Hereinafter, the same symbols are used to denote the same components as in Embodiment 6, and repeated descriptions are omitted.

[0131] like Figure 9 As shown, in the sliding surface S of the fixed-side sealing ring 5, a specified number of ( Figure 9 In the example, there is one) negative pressure generating mechanism 41 for the platform surface 46 and guide groove 49, which is provided circumferentially with a specified number of ( Figure 9 (There are 3 in the middle). The guide groove 49 covering approximately the entire area of ​​the negative pressure generating mechanism 41 is arranged facing the platform 46 located on the downstream side. In addition, the number of negative pressure generating mechanisms 41 arranged circumferentially with respect to the radial platform R4 is not limited to the embodiment, and can be 2 or 4, 5 or 6 or more. Furthermore, regarding the number of platform 46 respectively provided on the negative pressure generating mechanism 41, as long as it is possible to extend the sliding surfaces S to achieve a fluid lubrication state, it is not limited to this embodiment, and the number of platform 46 can be 2 or 3 or more.

[0132] like Figure 9 As shown, a positive pressure generating mechanism 47 is provided in a radial platform R4 between the sealed fluid side platform R1 and the leakage side platform R2. When viewed from the axial direction, the positive pressure generating mechanism 47 is a rectangular groove with a bottom, and has an opening 47a communicating with the fluid inlet groove 42. The portion other than the opening 47a is surrounded by the radial platform R4.

[0133] If the sliding component on the opposite side (rotating side sealing ring 3) is in the specified direction ( Figure 9When the shaft 1 rotates in the clockwise direction (counterclockwise direction in the figure), the fluid flows from the fluid introduction groove 42 to the positive pressure generating mechanism 47 through the opening portion 47a. The fluid flowing into the positive pressure generating mechanism 47 is intercepted in the positive pressure generating mechanism 47, and a positive pressure is generated by a wedge effect. By this positive pressure, even when the fluid lubrication state is not sufficient in a low-speed rotation state at the time of startup and the like, the liquid film formation at the time of startup can be assisted.

[0134] As described above, the sliding member according to Embodiment 7 has the following effects in addition to the effects of Embodiment 6.

[0135] By providing the positive pressure generating mechanism 47 in the radial land portion R4 of the negative pressure generating mechanism 41, even when the fluid lubrication state is not sufficient in a low-speed rotation state at the time of startup and the like, the liquid film formation at the time of startup can be assisted by the positive pressure generated by the positive pressure generating mechanism 47.

[0136] In addition, the positive pressure generating mechanism 47 is provided in a rectangular shape when viewed in the axial direction, but is not limited thereto, and can be a polygonal shape such as a triangle or a pentagon, a semicircle, a semioval, or the like.

[0137] The embodiments of the present application have been described above with reference to the drawings, but the specific structure is not limited to these embodiments, and modifications and additions within the scope of the gist of the present application are also included in the present application.

[0138] In the above embodiments, the outer peripheral side is provided as the sealed fluid side and the inner peripheral side is provided as the leakage side, but is not limited thereto, and can also be applied when the inner peripheral side is the sealed fluid side and the outer peripheral side is the leakage side.

[0139] The negative pressure generating mechanism, the land portion, and the guide groove can be provided on the sliding surface S of the stationary side seal ring 5, but can also be provided on the sliding surface S of the rotating side seal ring 3.

[0140] Symbol Explanation

[0141] 1 - mechanical seal, 2 - sleeve, 3 - rotating side seal ring, 4 - housing, 5 - stationary side seal ring, 6 - spiral wave spring, 7 - bellows, 8 - gasket, 9 - housing, 10 - rotating shaft, 21 - negative pressure generating mechanism, 22 - fluid introduction groove, 23 - groove portion, 24 - opening portion, 25 - end portion, 26 - land portion, 26a - wall portion, 26b - wall portion, 26c - wall portion, 26d - opening portion, 26e - internal space, 29 - guide groove, 29a - sealed fluid side guide groove, 29b - leakage side guide groove, 31 - negative pressure generating mechanism, 32 - fluid introduction groove, 33 - groove portion, 34 - opening portion, 35 - end portion, 36 - land portion, 36b - bridge portion, 39 - guide groove, 41 - negative pressure generating mechanism, 42 - fluid introduction groove, 43 - groove portion, 44 - opening portion, 45 - end portion, 46 - land portion, 46a - land portion, 46b - bridge portion, 46d - opening portion, 46e - internal space, 47 - positive pressure generating mechanism, 47a - opening portion, 49 - guide groove, R1 - sealed fluid side land portion, R2 - leakage side land portion, R3 - radial land portion, R4 - radial land portion, Rm - average diameter, S - sliding surface.

Claims

1. A pair of sliding members formed in a ring shape which slide against each other by sliding surfaces, characterized in that, one of an inner diameter side and an outer diameter side of the pair of sliding members is a sealed fluid side, and the other is a leakage side, at least one of the sliding surfaces is provided with at least one negative pressure generating groove, a ring-shaped leakage side deck portion formed on the leakage side and extending in a jointless manner in the circumferential direction, and at least one sealed fluid side deck portion formed on the sealed fluid side and extending in a jointed manner in the circumferential direction, the negative pressure generating groove is isolated from the leakage side by the leakage side deck portion, the negative pressure generating groove is partially divided by a side wall of the leakage side and a side wall of the sealed fluid side which face each other and simultaneously extend in the circumferential direction, and at least one of the sliding surfaces further includes a deck portion in a protruding shape which protrudes into the negative pressure generating groove from the side wall in the circumferential direction of the sealed fluid side toward the leakage side in a radial direction continuously from the sealed fluid side deck portion.

2. The sliding member according to claim 1, characterized in that, a bottom portion of the negative pressure generating groove is provided with a guide groove which faces the deck portion in the protruding shape from the leakage side.

3. The sliding member according to claim 1 or 2, characterized in that, bottom portions of the negative pressure generating groove are provided with guide grooves which respectively face the deck portion in the protruding shape from the leakage side and the sealed fluid side.

4. The sliding member according to claim 1 or 2, characterized in that, the negative pressure generating groove is disposed across an average diameter of the sliding surface.

5. The sliding member according to claim 1 or 2, characterized in that, the negative pressure generating groove is provided with a fluid introduction groove which communicates with the sealed fluid side, and a groove portion having an opening portion on a downstream side which communicates with the fluid introduction groove and a dead end portion on an upstream side which is surrounded by a deck portion.

6. The sliding member according to claim 5, characterized in that, a positive pressure generating groove is provided in the deck portion which surrounds the dead end portion, one end of the positive pressure generating groove communicating with the fluid introduction groove.

7. The sliding member according to claim 1 or 2, characterized in that, a plurality of the negative pressure generating grooves are disposed in the sliding surface.

8. The sliding member according to claim 1 or 2, characterized in that, a plurality of the deck portions in the protruding shape are disposed. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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