Sliding parts

Abstract

To provide sliding parts with smooth torque behavior. [Solution] A pair of sliding surfaces 11, 21, each having a dynamic pressure groove 13 formed on at least one of them, rotate relative to each other to partition a sealed fluid space S1 and a leak space S2. At least one of the sliding surfaces 11 has a circumferentially extending micro-groove 14 that is shallower than the dynamic pressure groove 13, and the micro-groove 14 extends across the tip region 13a on the tip 13B side of half the radial width dimension W1 of the dynamic pressure groove 13 (W12).

Description

Technical Field

[0001] The present invention relates to sliding parts that rotate relative to each other, and is used for sliding parts used in a shaft sealing device for sealing a rotating shaft of a rotating machine in, for example, the automotive, general industrial machinery, or other sealing fields, or for sliding parts used in a bearing of a machine in the automotive, general industrial machinery, or other bearing fields.

Background Art

[0002] As a shaft sealing device for preventing leakage of a sealed fluid, for example, a mechanical seal includes a pair of annular sliding parts that rotate relative to each other and whose sliding surfaces slide against each other. In such a mechanical seal, in recent years, reduction of energy lost due to sliding has been desired for environmental protection and other reasons.

[0003] For example, the mechanical seal shown in Patent Document 1 has a hydrodynamic groove provided in a stationary seal ring. The hydrodynamic groove extends in an arc shape from the outer diameter side, which is the side of the sealed fluid space, toward the inner diameter side, which is the side of the leakage space, and the closed end portion on the inner diameter side tapers.

[0004] Thereby, when the rotating seal ring rotates relative to the stationary seal ring, the sealed fluid that has flowed into the hydrodynamic groove from the sealed fluid space side flows out between the sliding surfaces from the tip on the inner diameter side of the hydrodynamic groove. The hydrodynamic pressure generated at this time separates the sliding surfaces from each other, and the introduction of the sealed fluid between the sliding surfaces improves the lubricity. In this way, the energy lost due to sliding can be reduced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the sliding component described in Patent Document 1, the leakage of the sealed fluid into the leakage space is suppressed by the fluid flowing into the space between the sliding surfaces as the sliding surfaces separate due to dynamic pressure.

[0007] More specifically, the sealed fluid that flows out from the dynamic pressure groove between the sliding surfaces has a high pressure, which prevents the fluid from leaking into the sealed fluid space. Furthermore, the sealed fluid, whose pressure decreases as it moves away from the dynamic pressure groove, is pushed back into the sealed fluid space by the fluid from the leak space. In addition, the position of high pressure continues to shift as the tip region of the dynamic pressure groove moves in accordance with relative rotation. Thus, the fluid pressure generated from the dynamic pressure groove is unbalanced, and the interface between the sealed fluid and the fluid in the leak space continues to fluctuate irregularly, hindering torque behavior.

[0008] This invention was made in view of these problems, and aims to provide a sliding part with smooth torque behavior. [Means for solving the problem]

[0009] To solve the aforementioned problems, the sliding component of the present invention is A sliding component comprising a pair of sliding surfaces, each having a dynamic pressure groove formed on at least one of them, which rotate relative to each other to partition a sealed fluid space and a leakage space, At least one of the sliding surfaces is provided with a minute groove extending in the circumferential direction that is shallower than the hydrodynamic groove. The aforementioned micro-grooves extend across the tip region of the dynamic pressure groove, beyond half of its radial width dimension. According to this, the fluid that flows out from the dynamic pressure groove between the sliding surfaces is homogenized by the micro-grooves. Therefore, the micro-grooves can suppress the generation of unbalanced fluid pressure caused by the dynamic pressure groove. In addition, micro-grooves that are shallower than the dynamic pressure groove have little effect on the fluid in the dynamic pressure groove. Therefore, sliding parts that can efficiently generate dynamic pressure in the dynamic pressure groove can easily form a fluid film between the sliding surfaces. Furthermore, micro-grooves that cross the tip region of the dynamic pressure groove can effectively homogenize the fluid in the tip region where pressure fluctuations are severe. As a result, the interface between the sealed fluid and the fluid on the leakage side between the sliding surfaces becomes more stable, allowing the sliding parts to exhibit smoother torque behavior.

[0010] Multiple of the aforementioned micro-grooves may be arranged at radial intervals. According to this, by providing multiple micro-grooves, sliding parts can more effectively equalize fluid pressure.

[0011] The radial width dimension of the micro groove may be shorter than the radial width dimension of the dynamic pressure groove. According to this, micro-grooves with a shorter radial width than dynamic pressure grooves are less likely to hinder the dynamic pressure effect generated in the dynamic pressure grooves, and can stabilize the interface while preventing uneven contact between sliding surfaces.

[0012] The aforementioned micro-grooves may be in communication with the aforementioned dynamic pressure grooves. According to this, the micro-grooves communicating with the tip region of the dynamic pressure groove can more effectively homogenize the fluid in the tip region where pressure fluctuations are intense.

[0013] The aforementioned micro-grooves may be concentric grooves. According to this, since the micro-grooves are arranged concentrically, there is no variation in the position of the interface between the sliding surfaces at radial positions corresponding to the relative rotational speed. In other words, the interface is formed along the micro-grooves, which further stabilizes the torque behavior.

[0014] The plurality of micro-grooves may also be provided in regions radially separated from the dynamic pressure grooves. According to this, since the micro-grooves also exist in the region where the hydrodynamic grooves are not provided, the fluctuating pressure can be effectively suppressed.

[0015] The plurality of micro-grooves may be provided in the radial direction from one end to the other end in the radial direction of the hydrodynamic groove. According to this, since the micro-grooves exist across the region where the hydrodynamic grooves are provided, the fluctuating pressure can be effectively suppressed.

[0016] The hydrodynamic groove formed on the sliding surface may be a negative pressure groove that generates a negative pressure and a positive pressure groove that generates a positive pressure. According to this, the fluctuating pressure in the hydrodynamic groove that generates a negative pressure where the pressure fluctuation is more significant can be effectively equalized.

Brief Description of the Drawings

[0017] [Figure 1] It is a longitudinal sectional view showing an example of a mechanical seal in Example 1 according to the present invention. [Figure 2] It is a view of the sliding surface of the stationary seal ring in Example 1 as seen from the axial direction. [Figure 3] It is a partially enlarged view in FIG. 2. [Figure 4] It is a cross-sectional view taken along line A-A in FIG. 3 [Figure 5] It is an enlarged view of the sliding surface of the stationary seal ring in Example 2 according to the present invention as seen from the axial direction. [Figure 6] It is a view of the sliding surface of the stationary seal ring in Example 3 according to the present invention as seen from the axial direction. [Figure 7] It is a partially enlarged view in FIG. 6. [Figure 8] It is a view of the sliding surface of the stationary seal ring in Example 4 according to the present invention as seen from the axial direction. [Figure 9] It is an enlarged view of the sliding surface of the stationary seal ring in Example 5 according to the present invention as seen from the axial direction. [Figure 10] It is a view of the sliding surface of the stationary seal ring in Example 6 according to the present invention as seen from the axial direction. [Figure 11] This is a view of the sliding surface of the stationary sealing ring in Embodiment 7 of the present invention, as seen from the axial direction. [Figure 12] This is an enlarged view of the sliding surface of the stationary sealing ring in Embodiment 8 of the present invention, as seen from the axial direction. [Modes for carrying out the invention]

[0018] Embodiments for implementing the sliding component according to the present invention will be described below based on examples. [Examples]

[0019] The sliding component according to Example 1 will be described with reference to Figures 1 to 4. In this example, the sliding component will be described as being applied to a mechanical seal.

[0020] Furthermore, in a mechanical seal, the sealed fluid F exists as the first fluid in the inner space S1, and the atmosphere A exists as the second fluid in the outer space S2. The inner diameter side of the sliding parts constituting the mechanical seal is described as the sealed fluid space side (high pressure side), and the outer diameter side is described as the leakage space side (low pressure side). Also, for the sake of explanation, dots may be added to grooves, etc., formed on the sliding surface in the drawings.

[0021] The automotive mechanical seal shown in Figure 1 is an outside-type seal that seals the fluid F to be sealed, which is attempting to leak from the inner diameter side to the outer diameter side of the sliding surface, and the outer space S2 is open to the atmosphere A. In this embodiment, the example shown is one in which the fluid to be sealed F is a high-pressure liquid and the atmosphere A is a gas at a lower pressure than the fluid to be sealed F.

[0022] The mechanical seal mainly consists of a stationary sealing ring 10 as an annular sliding component and a rotating sealing ring 20 as another annular sliding component. The rotating sealing ring 20 is mounted on the rotating shaft 1 via a sleeve 2 so as to be rotatable with the rotating shaft 1. The stationary sealing ring 10 is mounted on a seal cover 5 fixed to the housing 4 of the equipment to be mounted, in a non-rotatable and axially movable state. The stationary sealing ring 10 is biased axially by an elastic member 7 so that the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 slide in close contact with each other. The sliding surface 21 of the rotating sealing ring 20 is a flat surface, and this flat surface does not have any grooves or other recesses.

[0023] The stationary sealing ring 10 and the rotating sealing ring 20 are typically formed from two SiC (hard material) components or a combination of SiC (hard material) and carbon (soft material), but are not limited to this. Any sliding material used for mechanical seals is applicable. SiC can be sintered using boron, aluminum, carbon, etc., as sintering aids, or from materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC made of SiC and Si, SiC-TiC, SiC-TiN, etc. Carbon can be a mixture of carbonaceous and graphite, as well as resin-molded carbon and sintered carbon. In addition to the sliding materials mentioned above, metal materials, resin materials, surface modification materials (coating materials), and composite materials are also applicable.

[0024] As shown in Figures 2 and 3, the rotating sealing ring 20, which is the mating sealing ring, slides relative to the stationary sealing ring 10 in a counterclockwise direction as indicated by the solid arrows.

[0025] On the sliding surface 11 of the stationary sealing ring 10, multiple dynamic pressure grooves 13 (16 in this embodiment) are evenly arranged in the circumferential direction on the inner diameter side, and multiple minute grooves 14 (3 rows in the radial direction in this embodiment) are arranged between adjacent dynamic pressure grooves 13 (16 in the circumferential direction in this embodiment) so as to cross the tip region 13a (see inside the blowhole in Figure 3), which is the area on the tip side of half the radial width W1 of the dynamic pressure grooves 13.

[0026] Furthermore, the portion of the sliding surface 11 other than the dynamic pressure grooves 13 and micro-grooves 14 forms a flat land 12.

[0027] As shown in detail in Figure 3, the land 12 has a land 12a between adjacent dynamic pressure grooves 13 in the circumferential direction, a land 12b that extends continuously in an endless annular shape in the circumferential direction, and a land 12c between adjacent minute grooves 14 in the radial direction. Furthermore, the land 12b is located on the outer diameter side of the dynamic pressure grooves 13, lands 12a, and lands 12c. The upper surfaces (i.e., axial end faces) of each of these lands 12a, 12b, and 12c are arranged in the same plane and constitute the flat surface of the land 12.

[0028] As shown in Figure 3, the dynamic pressure groove 13 is formed in a triangular shape that inclins in the direction of rotation of the rotating sealing ring 20 toward the outer diameter from the open end 13E, which is one radial end communicating with the internal space S1. The dynamic pressure groove 13 is a positive pressure groove in which positive pressure is generated at the outer diameter tip 13B, which is the other radial end, and the tip region 13a, which is its vicinity, when the rotating sealing ring 20 rotates. The tip region 13a is the area on the tip 13B side of half the radial width dimension W1 of the dynamic pressure groove 13 W12, and the portion on the outer diameter side of the position indicated by the dashed line in the blowout in Figure 3 is included in this region. Furthermore, one radial end may be the tip 13B, and the other radial end may be the open end 13E.

[0029] The three micro-grooves 14 formed between adjacent pairs of dynamic pressure grooves 13 are curved grooves that extend continuously along the circumferential direction and are arranged in a row, approximately parallel to each other. In the following description, the three micro-grooves 14 formed between adjacent pairs of dynamic pressure grooves 13 may be simply referred to as "three micro-grooves 14".

[0030] Furthermore, the three microgrooves 14 are arranged concentrically. In addition, the circumferential ends of the three microgrooves 14 are connected to adjacent dynamic pressure grooves 13 in the circumferential direction. More specifically, the three microgrooves 14 are connected only to the tip region 13a of the dynamic pressure grooves 13. It should also be noted that the three microgrooves 14 can be referred to as a single group of microgrooves.

[0031] As shown in Figure 4, the radial width dimension W2 of each microgroove 14 is approximately the same. Furthermore, the pitch P of these microgrooves 14, i.e., the radial dimension between adjacent microgrooves 14, is approximately the same as the radial width dimension W2 of the microgroove 14 (W2=P). In addition, the radial width dimension W2 of the microgroove 14 is shorter than the radial width dimension W1 of the dynamic pressure groove 13 (W1>W2). The radial width dimension W2 of the microgroove 14 is preferably 1000 μm or less, and more preferably 50 to 200 μm.

[0032] Furthermore, the depth dimension D1 of the dynamic groove 13 is significantly longer than the depth dimension D2 of the micro-groove 14. More specifically, the depth dimension D1 is approximately 5 to 50 times the depth dimension D2 (D1 ≈ D2 × 5 to 50). Also, the depth dimension D1 is longer than the radial width dimension W2 of the micro-groove 14 (D1 > W2). Moreover, the depth dimension D2 is shorter than the radial width dimension W2 (D2 <W2)。

[0033] Next, the operation of the stationary sealing ring 10 and the rotating sealing ring 20 during relative rotation will be explained using Figure 3.

[0034] As the rotating sealing ring 20 rotates, the fluid to be sealed in the dynamic pressure groove 13 moves in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21, as shown by the white arrows in Figure 3, and the fluid to be sealed in the internal space S1 is drawn into the dynamic pressure groove 13. As a result, positive pressure is generated in the tip region 13a of the dynamic pressure groove 13, and the fluid to be sealed F flows out from the tip region 13a between the sliding surfaces 11 and 21. Therefore, lubrication between the sliding surfaces 11 and 21 can be improved.

[0035] Furthermore, the sealed fluid F that flows out from the tip region 13a between the sliding surfaces 11 and 21 is guided to the micro-grooves 14 located downstream in the relative rotation direction, as shown by the dashed arrows in Figure 3, and is homogenized. Therefore, the micro-grooves 14 can suppress the occurrence of unbalanced fluid pressure caused by the dynamic pressure grooves 13, mainly due to the circumferential distribution of the dynamic pressure grooves 13.

[0036] In addition, the micro-grooves 14, which are shallower than the dynamic pressure grooves 13, have little effect on the sealed fluid F within the dynamic pressure grooves 13. Therefore, the dynamic pressure grooves 13 can efficiently generate dynamic pressure. Furthermore, the stationary sealing ring 10 easily forms a fluid film between the sliding surfaces 11 and 21.

[0037] Furthermore, in addition to the fluid pressure of the sealed fluid F being higher than atmospheric pressure, the tip region 13a, where the pressure of the sealed fluid F is increased, is prone to severe pressure fluctuations. The micro-grooves 14 extend across this tip region 13a. Therefore, the micro-grooves 14 can effectively homogenize the fluid in the tip region 13a, where pressure fluctuations are severe.

[0038] As a result, the interface B1 between the sealed fluid F and the atmosphere A, shown by the dashed line in Figure 3, is more easily stabilized between the sliding surfaces 11 and 21, allowing the stationary sealing ring 10 to exhibit smooth torque behavior. Note that the interface B1 is represented by a dashed line for illustrative purposes, and its radial position and axial shape change depending on the relative rotational speed, etc. This is also true in other embodiments.

[0039] In particular, the sealed fluid F that flows locally radially from the tip region 13a will traverse the microgroove 14, more specifically, the extension of the microgroove 14. During this time, a portion of the sealed fluid F is guided by the microgroove 14.

[0040] Furthermore, in this embodiment, three micro-grooves 14 are provided. As a result, each time the sealed fluid F crosses a micro-groove 14, the amount and pressure moving toward the outer space S2 are reduced and continuously leveled. In this way, the three micro-grooves 14 suppress the flow and pressure of the sealed fluid F locally moving radially from the tip region 13a, and level the pressure in the circumferential direction. Therefore, the stationary sealing ring 10 can more effectively equalize the fluid pressure.

[0041] Furthermore, the two lands 12c, which have an extremely short radial width dimension P, can effectively guide the sealed fluid F between themselves and the sliding surface 21 into one of the three micro-grooves 14. In this way, multiple rows of micro-grooves 14 can be treated as a single group of micro-grooves to easily achieve a fluid pressure equalization function.

[0042] Furthermore, the micro-grooves 14, which have a shorter radial width dimension than the dynamic pressure grooves 13, are less likely to hinder the dynamic pressure effect generated in the dynamic pressure grooves 13. In addition, because they have a shorter radial width dimension than the dynamic pressure grooves 13, a sufficiently wide land 12 can be provided, thereby preventing uneven contact between the sliding surfaces 11 and 21 and stabilizing the interface B1. Moreover, the three micro-grooves 14, with lands 12c positioned between them, can distribute the sliding points even if the sliding surface 21 tilts slightly when sliding relative to the sliding surface 21. While it is possible to stabilize the interface B1 with a single row of micro-grooves 14, if this is difficult, the effect of stabilizing the interface B1 can be achieved by providing multiple rows of micro-grooves 14.

[0043] Furthermore, when high pressure is generated within the tip region 13a, a portion of the sealed fluid F within the tip region 13a is homogenized by the downstream micro-grooves 14 that communicate with the tip region 13a. In addition, the sealed fluid F flows out from the tip region 13a into the downstream micro-grooves 14, while the fluid is smoothly guided from the upstream micro-grooves 14 back into the tip region 13a. This also shows that the micro-grooves 14 communicating with the tip region 13a can more effectively homogenize the sealed fluid F within the tip region 13a, where pressure fluctuations are intense. In particular, providing the micro-grooves 14 so as to cross the area where the dynamic pressure reaches its peak is expected to yield even greater results.

[0044] Furthermore, the concentrically arranged micro-grooves 14 can guide the sealed fluid F along the concentric lines. As a result, between the sliding surfaces 11 and 21, there is no variation in the position of the interface B1 at radial positions corresponding to the rotational speed; in other words, the interface B1 is formed along radial positions corresponding to the rotational speed. This allows the stationary sealing ring 10 to stabilize the torque behavior more effectively.

[0045] Although it was explained that the micro-grooves 14 are provided in a configuration of three in the radial direction, this is not the only configuration; one or more in the radial direction are sufficient, and in this case as well, the interface B1 can be stabilized. [Examples]

[0046] Next, the sliding component according to Example 2 will be described with reference to Figure 5. Note that the description of components that are identical to those in Example 1 and therefore redundant will be omitted.

[0047] In this embodiment 2, the sliding surface 111 of the stationary sealing ring 110 has three micro-grooves 114, and their circumferential ends 114a and 114b are spaced apart from the tip regions 113a of each circumferentially adjacent dynamic pressure groove 113. That is, all three micro-grooves 114 have closed ends near the tip region 113a and are not in communication with the tip region 113a.

[0048] As a result, as indicated by the white arrows, the sealed fluid F that flows out from the tip region 113a between the sliding surfaces 111 and 21 is guided and dispersed into the three minute grooves 114 located downstream in the relative rotation direction, as indicated by the dashed arrows, and is homogenized.

[0049] In this case, it is preferable that the distance between the upstream end 114a in the relative rotational direction of the micro-grooves 114 and the tip region 113a is short so that the fluid that has moved from the tip region 113a to the land 12a is guided more smoothly into the three micro-grooves 114.

[0050] Furthermore, the fluid that has been guided downstream in the relative rotational direction by the three minute grooves 114 upstream of the dynamic pressure groove 113 due to the rotation of the rotating sealing ring 20 is introduced into the tip region 113a of the dynamic pressure groove 113.

[0051] In this case, it is preferable that the distance between the downstream end 114b in the relative rotation direction of the three micro-grooves 114 and the tip region 113a is short so that the fluid that has moved from the downstream end 114b in the relative rotation direction of the three micro-grooves 114 to the land 12a is introduced more smoothly into the tip region 113a.

[0052] Furthermore, the sufficiently shallow micro-grooves 114 prevent a pressure increase when the sealed fluid F moves from the downstream end 114b in the relative rotation direction to the land 12. As a result, pressure fluctuations in the micro-grooves 114 are prevented on the sliding surface 111.

[0053] As mentioned above, even if the dynamic pressure groove 113 and the micro-groove 114 are discontinuous, fluid can still be guided. Therefore, the dynamic pressure groove and the micro-groove only need to be capable of guiding fluid. [Examples]

[0054] Next, the sliding parts according to Embodiment 3 will be described with reference to Figures 6 and 7. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0055] In this embodiment 3, the sliding surface 211 of the stationary sealing ring 210 is provided with a plurality of dynamic pressure grooves 13, a plurality of (12 rows in this embodiment) of minute grooves 14 provided between adjacent dynamic pressure grooves 13, and a plurality of (20 rows in the radial direction in this embodiment) of minute grooves 15 that extend continuously in an endless ring shape in the circumferential direction in a region 211a radially separated from the dynamic pressure grooves 13.

[0056] The multiple micro-grooves 14 between the dynamic pressure grooves 13 are arc-shaped and linear grooves that extend continuously along the circumferential direction, and are arranged in rows that are substantially parallel to each other.

[0057] The multiple microgrooves 15 are circular and linear grooves that extend continuously along the circumferential direction, and are arranged in rows that are substantially parallel to each other. The other configurations are substantially the same as those of the microgrooves 14.

[0058] Furthermore, the lands 212 on the sliding surface 211 have lands 12c between adjacent micro-grooves 14 and lands 12d between adjacent micro-grooves 15. The upper surfaces (i.e., axial end faces) of each of these lands 12c and 12d are arranged in the same plane and constitute the flat surface of the land 12. In other words, micro-grooves 14 and 15 are formed on the sliding surface 211 in the radial direction.

[0059] More specifically, on the sliding surface 211, multiple micro-grooves 14 are provided radially from the open end 13E to the tip 13B of the dynamic pressure groove 13. In addition, multiple micro-grooves 15 are provided radially from the tip 13B of the dynamic pressure groove 13 to the outer diameter end 211a of the sliding surface 211.

[0060] As a result, as shown by the white arrows in Figure 7, the sealed fluid F that flows out from the tip region 13a of the dynamic pressure groove 13 between the sliding surfaces 211, 21 is homogenized not only by the multiple micro-grooves 14 located downstream in the relative rotation direction, as shown by the dashed arrows in Figure 7, but also by the multiple micro-grooves 15. Therefore, the multiple micro-grooves 14, 15 can more efficiently suppress the generation of unbalanced fluid pressure caused by the dynamic pressure groove 13.

[0061] More specifically, the sealed fluid F flowing from the dynamic pressure groove 13 and the inner space S1 between the sliding surfaces 211 and 21 needs to cross the micro-groove 14 in order to move toward the outer space S2. During this process, a portion of the sealed fluid F is homogenized by the micro-groove 14. As a result, each time the sealed fluid F crosses the micro-groove 14, the amount and pressure of fluid moving toward the outer space S2 is continuously reduced.

[0062] Furthermore, the sealed fluid F that flows out from the dynamic pressure groove 13 between the sliding surfaces 211 and 21 must cross the micro-groove 15 in order to move towards the outer space S2. During this process, a portion of the sealed fluid F is guided by the micro-groove 15. As a result, each time the sealed fluid F crosses the micro-groove 15, the amount and pressure of fluid F moving towards the outer space S2 is continuously reduced. The same applies to the air A that flows in from the outer space S2 between the sliding surfaces 211 and 21.

[0063] As a result, the multiple micro-grooves 14 and 15 suppress the flow and pressure of the sealed fluid F locally directed radially from the dynamic pressure groove 13, thereby equalizing the pressure in the circumferential direction. Therefore, the interface B1 between the sealed fluid F and the atmosphere A, shown by the dashed line in Figure 7, becomes more stable between the sliding surfaces 211 and 21, allowing the static sealing ring 210 to exhibit even smoother torque behavior.

[0064] Furthermore, the sliding surface 211, which has minute grooves 14 and 15 formed radially, makes it easier to retain the sealed fluid F and atmosphere A between the sliding surfaces 211 and 21. As a result, the sliding surface 211 can reduce the starting torque when the rotating sealing ring 20 starts to rotate.

[0065] Furthermore, the sliding surface 211, which has minute grooves 14 and 15 formed radially, also has lands 12c and 12d formed radially. This allows for the distribution of contact points even if the sliding surface 21 tilts slightly during relative sliding, thus preventing uneven contact.

[0066] In this embodiment, the sliding surface has been described as having multiple micro-grooves 14 and 15 formed radially. However, the embodiment is not limited to this configuration, and the number of micro-grooves 14 and 15 can be changed as appropriate, as long as there are multiple. For example, only the micro-grooves 14 may be provided radially from one end to the other of the dynamic pressure groove 13, or one or more micro-grooves 15 may be formed only near the outer diameter side of the dynamic pressure groove 13.

[0067] In addition, although the configuration described has been that the multiple micro-grooves 14 are provided radially from the open end 13E to the tip 13B, it is not limited to this configuration. They may also be formed at positions spaced apart from the tip 13B towards the open end 13E, in other words, they do not have to cross the tip 13B. The same applies to the open end 13E side. That is, in the present invention, one radial end and the other radial end are not limited to including those ends.

[0068] Furthermore, the multiple micro-grooves formed on the sliding surface and spaced apart in the radial direction may be, for example, a combination of one micro-groove 14 and one micro-groove 15, and if multiple are provided, the types of micro-grooves may be different. The same applies to the micro-grooves 17 and 19 described later. [Examples]

[0069] Next, the sliding component according to Embodiment 4 will be described with reference to Figure 8. Note that the description of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0070] In the stationary sealing ring 310 of this embodiment 4, the sliding surface 311 has multiple dynamic pressure grooves 13, multiple micro grooves 14, and multiple micro grooves 15, as well as multiple dynamic pressure grooves 16 evenly arranged in the circumferential direction on the outer diameter side, and multiple micro grooves 17 arranged so as to cross the tip region 16a of the dynamic pressure grooves 16.

[0071] The dynamic pressure groove 16 is formed in a triangular shape that inclins toward the inner diameter side from the opening communicating with the outer space S2 toward the rotational direction of the rotating sealing ring 20. The dynamic pressure groove 16 is a positive pressure groove in which positive pressure is generated at the inner diameter side tip and its vicinity, the tip region 16a, when the rotating sealing ring 20 rotates. The other configurations are substantially the same as those of the dynamic pressure groove 13.

[0072] Multiple micro-grooves 17 have their circumferential ends connected to adjacent dynamic pressure grooves 16 in the circumferential direction. The other configurations are substantially the same as those of the micro-grooves 14.

[0073] Multiple micro-grooves 15 are provided between the dynamic pressure grooves 13 and 16 in the radial direction on the sliding surface 311.

[0074] As a result, as indicated by the white arrows, in addition to the sealed fluid F that flows out between the sliding surfaces 311 and 21 from the tip region 13a of the dynamic pressure groove 13, air A also flows out between the sliding surfaces 311 and 21 from the tip region 16a of the dynamic pressure groove 16, thereby improving lubrication more efficiently.

[0075] Furthermore, the atmospheric air A that flows out from the tip region 16a of the dynamic pressure groove 16 to the sliding surfaces 311 and 21 under increased pressure allows the stationary sealing ring 310 to more efficiently prevent the sealed fluid F from leaking into the outside space S2.

[0076] Furthermore, as indicated by the dashed arrows, the sealed fluid F that flows out from the tip region 13a of the dynamic pressure groove 13 between the sliding surfaces 311 and 21 is homogenized by the multiple micro-grooves 14 and 15. In addition, the air A that flows out from the tip region 16a of the dynamic pressure groove 16 between the sliding surfaces 311 and 21 is also homogenized by the multiple micro-grooves 15 and 17. Therefore, it is possible to suppress the occurrence of unbalanced fluid pressure caused by the dynamic pressure grooves 13 and 16.

[0077] Thus, even in a configuration where pressure fluctuations are likely to occur not only on the inner diameter side but also on the outer diameter side, the stationary sealing ring 310 makes it easier to stabilize the interface B2 between the sealed fluid F and the atmosphere A, as shown by the dashed line. Therefore, the stationary sealing ring 310 can smooth the torque behavior. [Examples]

[0078] Next, the sliding component according to Embodiment 5 will be described with reference to Figure 9. Note that the description of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0079] In the static sealing ring 410 of this embodiment 5, the sliding surface 411 has multiple dynamic pressure grooves 13, multiple micro grooves 14, and multiple micro grooves 15, as well as multiple dynamic pressure grooves 18 evenly arranged in the circumferential direction on the outer diameter side, and multiple micro grooves 19 arranged so as to cross the tip region 18a of the dynamic pressure grooves 18.

[0080] The dynamic pressure groove 18 is formed in a triangular shape that inclins in the counter-rotation direction of the rotating sealing ring 20 toward the inner diameter side from the opening that communicates with the outer space S2. The dynamic pressure groove 18 is a negative pressure groove in which negative pressure is generated at the inner diameter side tip and its vicinity, the tip region 18a, when the rotating sealing ring 20 rotates. The other configurations are substantially the same as those of the dynamic pressure groove 13.

[0081] Multiple micro-grooves 19 are connected to adjacent dynamic pressure grooves 18. The other configurations are substantially the same as those of the micro-grooves 17.

[0082] As the rotating sealing ring 20 is rotated, the air A in the dynamic pressure groove 18 moves in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21, as shown by the white arrow, and is returned to the outside space S2. As a result, negative pressure is generated in the tip region 18a of the dynamic pressure groove 18, and air A flows into the tip region 18a from between the sliding surfaces 411 and 21.

[0083] Furthermore, in the tip region 18a of the dynamic pressure groove 18 where negative pressure is generated, pressure fluctuations tend to occur more easily than in the tip region 13a of the dynamic pressure groove 13 where positive pressure is generated. Even in such a tip region 18a, the micro-grooves 19 can effectively equalize the pressure in the tip region 18a, as shown by the dashed arrows. As a result, the interface B3 between the sealed fluid F and the atmosphere A, shown by the dashed line, is more easily stabilized, and the stationary sealing ring 410 can exhibit smooth torque behavior. [Examples]

[0084] Next, the sliding component according to Embodiment 6 will be described with reference to Figure 10. Note that the description of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0085] The mechanical seal to which the stationary sealing ring 510 of this embodiment 6 is applied is an inside type that seals the fluid F to be sealed that is about to leak from the outer diameter side to the inner diameter side of the sliding surfaces 511,21, and the inner space S1 is open to the atmosphere A.

[0086] Furthermore, the sliding surface 511 is provided with a plurality of dynamic pressure grooves 16 and a plurality of micro-grooves 17. The dynamic pressure grooves 16 and micro-grooves 17 have substantially the same structure as in Embodiment 4, but the plurality of micro-grooves 17 communicate only with the tip region 16a of the dynamic pressure groove 16, similar to Embodiment 1. In other words, the sliding surface 511 of Embodiment 6 is an adaptation of the sliding surface 11 of Embodiment 1 to the inside side.

[0087] Even with this configuration, as indicated by the white arrow, the sealed fluid F that flows out from the tip region 16a of the dynamic pressure groove 16 between the sliding surfaces 511 and 21 can improve the lubrication between the sliding surfaces 511 and 21.

[0088] Furthermore, as shown by the dashed arrows, the sealed fluid F that flows out between the sliding surfaces 511 and 21 from the tip region 16a of the dynamic pressure groove 16 is also homogenized by the multiple minute grooves 17. Therefore, it is possible to suppress the occurrence of unbalanced fluid pressure caused by the dynamic pressure groove 16. As a result, the interface B4 between the sealed fluid F and the atmosphere A, shown by the dashed line, is more easily stabilized, and the stationary sealing ring 510 can exhibit smooth torque behavior.

[0089] Thus, the mechanical seal to which the sliding component of the present invention is applied may be of the inside type. This is also true for Examples 2 to 5. That is, in Examples 2 to 5, air A may be present in the inner space S1 and the sealed fluid F may be present in the outer space S2. [Examples]

[0090] Next, the sliding component according to Embodiment 7 will be described with reference to Figure 11. Note that the description of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0091] The mechanical seal to which the stationary sealing ring 610 of this embodiment 7 is applied is of the inside type.

[0092] The sliding surface 611 of the stationary sealing ring 610 has multiple dynamic pressure grooves 613, multiple micro grooves 614, multiple micro grooves 615, multiple dynamic pressure grooves 616, multiple micro grooves 617, as well as a deep groove 630 and multiple shallow grooves 640 evenly distributed in the circumferential direction. The micro grooves 614, 615, and the multiple micro grooves 617 have the same groove width and pitch. Also, in the blowout in Figure 11, the dots have been omitted to make the micro grooves more visible.

[0093] The deep groove 630 has a plurality of communicating grooves 631 that extend radially toward the inner diameter side from an opening that communicates with the outer space S2, and an endless annular circumferential groove 632 through which the plurality of communicating grooves 631 communicate.

[0094] According to this, the stationary sealing ring 610 can introduce the fluid to be sealed F from the outer space S2 toward the circumferential groove 632. Therefore, the stationary sealing ring 610 can ensure that the amount of fluid to be sealed F supplied between the sliding surfaces 611 and 21 over a wide circumferential range of the circumferential groove 632 is maintained. As a result, the stationary sealing ring 610 can suppress the occurrence of poor lubrication.

[0095] The shallow groove 640 extends circumferentially toward the rotational direction of the rotating sealing ring 20 from an opening that communicates with the communicating groove 631 in the deep groove 630. The shallow groove 640 is a positive pressure groove in which positive pressure is generated at the downstream end in the relative rotational direction and in its vicinity when the rotating sealing ring 20 rotates.

[0096] The dynamic pressure groove 613 is formed in a spiral shape that inclins toward the outer diameter side from the opening communicating with the inner space S1 in the direction of rotation of the rotating sealing ring 20. The dynamic pressure groove 616 is formed in a spiral shape that inclins toward the inner diameter side from the opening communicating with the circumferential groove portion 632 in the deep groove 630 in the direction of rotation of the rotating sealing ring 20. The dynamic pressure grooves 613 and 616 are positive pressure grooves in which positive pressure is generated at the inner diameter side tip and its vicinity, the tip regions 613a and 616a, when the rotating sealing ring 20 rotates.

[0097] The micro-groove 614 communicates with the adjacent hydrodynamic groove 613. The micro-groove 615 is an endless annular groove located between the hydrodynamic grooves 613 and 616 in the radial direction of the sliding surface 611. The micro-groove 617 communicates with the adjacent hydrodynamic groove 616. The other configurations are substantially the same as those of the micro-groove 14.

[0098] As indicated by the white arrows, the stationary sealing ring 610 allows air A from the internal space S1 to flow between the sliding surfaces 611 and 21 through the dynamic pressure groove 613 when the rotating sealing ring 20 rotates, and allows the sealed fluid F in the circumferential groove portion 632 of the deep groove 630 to flow between the sliding surfaces 611 and 21 through the dynamic pressure groove 616.

[0099] As a result, the stationary sealing ring 610 can introduce the fluid to be sealed in the outer space S2 to the inner diameter side through the shallow groove 640 when the rotating sealing ring 20 rotates. Therefore, the stationary sealing ring 610 can improve sliding performance by allowing a large amount of the fluid to be sealed F to flow out between the sliding surfaces 611 and 21.

[0100] Furthermore, as indicated by the dashed arrows, between the sliding surfaces 611 and 21, the air A that flows out from the tip region 613a of the dynamic pressure groove 613 between the sliding surfaces 611 and 21 is homogenized by the multiple micro-grooves 614 and 615, and the sealed fluid F that flows out from the tip region 616a of the dynamic pressure groove 616 between the sliding surfaces 611 and 21 is also homogenized by the multiple micro-grooves 615 and 617.

[0101] Therefore, the static sealing ring 610 can suppress the generation of unbalanced fluid pressure caused by the dynamic pressure grooves 613 and 616. As a result, the interface between the sealed fluid F and the atmosphere A is more easily stabilized, and the static sealing ring 610 can smooth the torque behavior.

[0102] Furthermore, the stationary sealing ring 610 in this embodiment 7 may also be applied to an outside-type mechanical seal. [Examples]

[0103] Next, the sliding component according to Embodiment 8 will be described with reference to Figure 12. Note that the description of components that are identical to those in Embodiment 3 and therefore redundant will be omitted.

[0104] The mechanical seal to which the stationary sealing ring 710 of this embodiment 8 is applied is of the outside type.

[0105] The sliding surface 711 of the stationary sealing ring 710 is provided with a plurality of dynamic pressure grooves 713, a plurality of micro grooves 714S, 714L, and a plurality of micro grooves 15.

[0106] The dynamic groove 713 is a so-called Rayleigh step, consisting of a rectangular shallow groove 713b that extends continuously along the circumferential direction and a rectangular deep groove 713c that extends continuously along the radial direction.

[0107] The micro-groove 714S communicates with the deep groove 713c located downstream in the relative rotation direction and the shallow groove 713b located upstream. The micro-groove 714L communicates with the deep groove 713c located downstream in the relative rotation direction and the deep groove 713c located upstream. The other configurations are substantially the same as those of the micro-groove 14.

[0108] As indicated by the white arrow, the stationary sealing ring 710 is a positive pressure groove in which, when the rotating sealing ring 20 rotates, the fluid to be sealed in the shallow groove 713b of the dynamic pressure groove 713 moves in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21, and positive pressure is generated at the tip located downstream in the relative direction of rotation and in the tip region 713a, which is near the tip.

[0109] Furthermore, as indicated by the white arrows, the fluid to be sealed F is supplied to the shallow groove 713b of the dynamic pressure groove 713 from the deep groove 713c of the dynamic pressure groove 713. As a result, the stationary sealing ring 710 can suppress the occurrence of poor lubrication and stably allow the fluid to be sealed F to flow between the sliding surfaces 711 and 21 from the shallow groove 713b of the dynamic pressure groove 713.

[0110] Furthermore, as indicated by the dashed arrows, the sealed fluid F that flows out from the tip region 713a of the dynamic pressure groove 713 between the sliding surfaces 711 and 21 is homogenized by the multiple minute grooves 714S, 714L, and 15. This prevents the occurrence of unbalanced fluid pressure caused by the dynamic pressure groove 713. As a result, the interface B1 between the sealed fluid F and the atmosphere A, indicated by the dashed line, is more easily stabilized, allowing the stationary sealing ring 710 to exhibit smooth torque behavior.

[0111] Furthermore, the stationary sealing ring 710 in this embodiment 8 may also be applied to an outside-type mechanical seal.

[0112] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0113] For example, in the above embodiments 1 to 8, automotive mechanical seals were used as examples of sliding parts, but other mechanical seals such as those used in general industrial machinery may also be used. Furthermore, the invention is not limited to mechanical seals, but may also use sliding parts other than mechanical seals, such as sliding bearings.

[0114] Furthermore, although the sealed fluid was described as a high-pressure liquid in Examples 1 to 8, it is not limited to this and may be a gas or a low-pressure liquid, or a mist-like mixture of liquid and gas.

[0115] Furthermore, although the fluid on the leakage space side was described as air, which is a low-pressure gas, in Examples 1 to 8 above, it is not limited to this and may be a liquid or a high-pressure gas, or it may be a mist-like mixture of liquid and gas.

[0116] Furthermore, in Examples 1 to 8, the sealed fluid space side has been described as the high-pressure side and the leak space side as the low-pressure side. However, the sealed fluid space side may be the low-pressure side and the leak space side may be the high-pressure side, or the sealed fluid space side and the leak space side may be at approximately the same pressure.

[0117] Furthermore, while examples 1 to 8 described above illustrate the provision of dynamic pressure grooves and microgrooves on a stationary sealing ring, dynamic pressure grooves and microgrooves may also be provided on a rotating sealing ring. Moreover, dynamic pressure grooves and microgrooves may be provided on different sealing rings.

[0118] Furthermore, although the microgrooves in Examples 1 to 8 were described as being curved or endlessly ring-shaped extending concentrically, they are not limited to these shapes. They may be inclined relative to the concentricity, linear, spiral, dashed, or wave-shaped, and their shape may be modified as appropriate. Moreover, a single microgroove may form a vortex shape that continuously revolves along the circumferential direction of the sliding surface, and multiple microgrooves may be arranged in the radial direction.

[0119] Furthermore, while the shapes of the dynamic pressure grooves in Examples 1 to 8 were described using examples such as triangular, spiral, and Rayleigh step shapes, the examples are not limited to these and may be modified as appropriate.

[0120] Furthermore, in Examples 1 to 8, it was explained that the depth dimension of the dynamic pressure groove was approximately 5 to 50 times deeper than the depth dimension of the micro-groove, but this is not limited to this, and the respective depth dimensions may be changed as appropriate, and it is preferable that the depth dimension of the dynamic pressure groove is greater than the depth dimension of the micro-groove. [Explanation of Symbols]

[0121] 10 Stationary sealing ring 11 Sliding surface 13 Dynamic pressure groove 13a Tip area 13B Tip (the other end in the radial direction) 13E Open end (one end in the radial direction) 14 Micro groove 18. Dynamic pressure groove (negative pressure groove) 20 Rotating sealing ring (sliding part) 21 Sliding surface 110 Stationary sealing ring 111 Sliding surface 113 Dynamic pressure groove 114 Micro groove 210,310,410,510 Stationary sealing ring 211, 311, 411, 511 Sliding surface 15 Micro groove 16 Dynamic pressure groove 16a Tip area 17 Micro groove 18 Dynamic pressure groove 18a Tip area 19 Micro groove 610 Stationary sealing ring 611 Sliding surface 613,616 Dynamic pressure groove 613a,616a Tip region 614,615,617 Micro groove 710 Stationary sealing ring 711 Sliding surface 713 Dynamic pressure groove 713a Tip area 714L,714S Micro groove A. Atmosphere (fluid on the leak side) B1~B5 interface D1, D2 Depth dimensions F Sealed fluid Pitch S1 Inner space (sealed fluid space) S2 External space (leakage space) W1 Radial width dimension of the dynamic pressure groove W2 Radial width dimension of the micro-groove

Claims

1. A sliding component comprising a pair of sliding surfaces, each having a dynamic pressure groove formed on at least one of them, which rotate relative to each other to partition a sealed fluid space and a leakage space, At least one of the sliding surfaces is provided with a minute groove extending in the circumferential direction that is shallower than the hydrodynamic groove. The aforementioned minute groove is a sliding component that extends across the tip region of the dynamic pressure groove, beyond half of its radial width dimension.

2. The sliding component according to claim 1, wherein the micro-grooves are arranged in a plurality at radially spaced intervals.

3. The sliding component according to claim 1, wherein the radial width dimension of the micro groove is shorter than the radial width dimension of the dynamic pressure groove.

4. The sliding component according to any one of claims 1 to 3, wherein the minute groove is in communication with the dynamic pressure groove.

5. The sliding component according to claim 4, wherein the minute groove is a concentric arc-shaped groove.

6. The sliding component according to claim 2, wherein the plurality of minute grooves are also provided in a region radially separated from the dynamic pressure groove.

7. The sliding component according to claim 2, wherein the plurality of minute grooves are provided radially from one end to the other end of the dynamic pressure groove.

8. The sliding component according to claim 1, wherein the dynamic pressure groove formed on the sliding surface comprises a negative pressure groove that generates negative pressure and a positive pressure groove that generates positive pressure.

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