Patent Publication Number: US-2023160475-A1

Title: Sliding component

Description:
TECHNICAL FIELD 
     The present invention relates to a pair of sliding components that slide relative to each other by sliding surfaces, for example, a mechanical seal, a sliding bearing, and other sliding components suitable for a sliding portion. In particular, the present invention relates to a sliding component including a sealing ring or a bearing that is required to have fluid interposing between sliding surfaces to reduce friction and prevent fluid from leaking from the sliding surfaces. 
     BACKGROUND ART 
     As a sealing device configured to prevent leakage of sealed fluid, there is known a sealing device (for example, a mechanical seal) including a pair of sliding components that relatively slide on sliding surfaces. In such a sealing device, it is necessary to maintain favorable sealing performance while reducing sliding torque by forming a fluid lubrication film by the sealed fluid between the sliding surfaces. As one method for achieving favorable sealing performance and low sliding torque, there is known a technique of arranging a plurality of dimples in a sliding surface. 
     For example, it is known that favorable sealing performance and low sliding torque may be achieved by arranging dimples each including a circular opening portion in a sliding surface on a virtual circumference line having a center coincide with a rotation center of a sliding component. (For example, see Patent Literature 1). 
     In addition, it is also known that dimples each including an elongated rectangular opening portion whose end portion is semicircular are arranged at a predetermined dimple angle θ, and a ratio L1/L2 of a dimple circumferential length L1 on a circle passing through a dimple center to a circumferential length L2 of a land portion between adjacent dimples on the same circle is set to 0.001≤L1/L2≤0.1, thereby optimally adjusting sealing performance and sliding torque of the dimples as a whole (see, for example, Patent Literature 2). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP-A-2010-133496 
     Patent Literature 2: Japanese Patent No. 5456772 
     SUMMARY OF INVENTION 
     Technical Problem 
     According to the technique of Patent Literature 1, even though favorable sealing performa.nce and low sliding torque may be achieved under specific operating conditions, the favorable sealing performance and low sliding torque cannot be achieved in a wide rotation speed range. 
     In addition, according to the technique of Patent Literature 2, since the dimple angle is fixed, even though leakage of sealed fluid and sliding torque may be reduced under specific operating conditions, favorable sealing performance and low sliding torque cannot be achieved in a wide rotation speed range. In particular, when used in reverse rotation, there is a tendency that the sealing performance is lowered and the sliding torque is increased. 
     An object of the present invention is, a pair of sliding components that relatively slide on sliding surfaces, to provide the sliding components capable of achieving favorable sealing performance and low sliding torque regardless of a rotation direction and when used in a wide rotation speed range. 
     Solution to Problem 
     In order to solve the above problem, a sliding component of the present invention is: 
     a pair of sliding members being slidable relative to each other on sliding surfaces of the sliding members. 
     At least one of the sliding surfaces includes a dimple group in which a plurality of dimples is arranged, each of the dimple having an opening portion whose shape has a long axis and a short axis orthogonal to the long axis, and 
     in the dimple group, the dimples are arranged along a curve having a curvature different from a curvature of a circumference of the sliding surface. 
     According to this feature, in the dimple group, the dimples are arranged along the curve having the curvature different from the curvature of the circumference of the sliding surface, so that angles of the dimples gradually change along the curve. As a result, since dimples having different suction effects and dynamic pressure effects are included, the dimple group as a whole can exhibit favorable sealing performance and low sliding torque over a wide rotation speed range. 
     The sliding component according to the present invention is characterized in that 
     the dimple group includes a first dimple group in which the dimples are arranged along a curve that is convex toward a sealed fluid side of the sliding component. 
     According to this feature, since the dimples in the first dimple group are arranged along the curve that is convex toward the sealed fluid side, angles of the dimples gradually change along the curve that is convex toward the sealed fluid side. As a result, the first dimple group includes dimples having different suction effects and dynamic pressure effects, so that the dimple group as a whole can exhibit favorable sealing performance and low sliding torque over a wide rotation speed range, and further, a dimple group capable of bidirectional rotation can be easily formed. 
     The sliding component according to the present invention is characterized in that 
     the first dimple group is arranged on a leakage side of the sliding surface. 
     According to this feature, since the first dimple group is arranged on the leakage side, fluid from the leakage side is suctioned by the first dimple group, and thus sealing performance can be improved. 
     The sliding component according to the present invention is characterized in that 
     the dimple group includes a second dimple group in which the dimples are arranged along a curve that is convex toward a leakage side of the sliding component. 
     According to this feature, since the dimples in the second dimple group are arranged along the curve that is convex toward the leakage side, angles of the dimples gradually change along the curve that is convex toward the leakage side. As a result, the second dimple group includes dimples having different suction effects and dynamic pressure effects, so that the dimple group as a whole can exhibit favorable sealing performance and low sliding torque over a wide rotation speed range, and further, a dimple group capable of bidirectional rotation can be easily formed. 
     The sliding component according to the present invention is characterized in that 
     the second dimple group is arranged on a sealed fluid side of the sliding surface. 
     According to this feature, since the second dimple group is arranged on the sealed fluid side, fluid from the sealed fluid side is suctioned by the second dimple group, and the fluid is pressurized and supplied to the sliding surface, so that a fluid film is formed on the sliding surface, and thus sliding torque can be reduced. 
     The sliding component according to the present invention is characterized in that 
     the dimple group includes: a first dimple group in which the dimples are arranged along a curve that is convex toward a sealed fluid side of the sliding component; and a second dimple group in which the dimples are arranged along a curve that is convex toward a leakage side of the sliding component. 
     According to this feature, since the dimples in the first dimple group are arranged in the curved shape that is convex toward the sealed fluid side, and the dimples in the second dimple group are arranged in the curved shape that is convex toward the leakage side, so that the first dimple group and the second dimple group can change angles of the dimples along the respective curves, and thus the dimple groups as a whole can exhibit favorable sealing performance and low sliding torque over a wide rotation speed range, and further, dimple groups capable of bidirectional rotation can be easily formed. 
     The sliding component according to the present invention is characterized in that 
     the first dimple group is arranged on the leakage side of the sliding surface, and the second dimple group is arranged on the sealed fluid side of the sliding surface. 
     According to this feature, since the first dimple group arranged on the leakage side can improve sealing performance, and the second dimple group arranged on the sealed fluid side can improve lubricity, a sliding product with favorable sealing performance and lubricity can be achieved. 
     The sliding component according to the present invention further includes: 
     a circumferential groove extending in a circumferential direction and disposed between the first dimple group and the second dimple group. 
     According to this feature, interference between the first dimple group and the second dimple group can be prevented by the circumferential groove extending in the circumferential direction between the first dimple group and the second dimple group. 
     The sliding component according to the present invention is characterized in that 
     the sliding surface includes a plurality of regions partitioned by land portions extending in a corresponding radial direction, and the dimple group is disposed in one of the regions. 
     According to this feature, since fluid flowing through the dimple group is dammed and pressurized by the land portion, the sliding surface is expanded and thus lubricity can be improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a vertical cross-sectional view showing an example in which a sliding component according to the present invention is applied to a mechanical seal; 
         FIG.  2    is taken along line W-W of  FIG.  1   , which shows an example of a sliding surface of a sliding component according to Embodiment 1 of the present invention; 
         FIG.  3    is taken along line W-W of  FIG.  1   , which shows an example of a sliding surface of a sliding component according to Embodiment 2 of the present invention; 
         FIG.  4    is taken along line W-W of  FIG.  1   , which shows an example of a sliding surface of a sliding component according to Embodiment 3 of the present invention; 
         FIG.  5    is taken along line W-W of  FIG.  1   , which shows an example of a sliding surface of a sliding component according to Embodiment 4 of the present invention; 
         FIG.  6    is taken along line W-W of  FIG.  1   , which shows an example of a sliding surface of a sliding component according to Embodiment 5 of the present invention; 
         FIG.  7    is taken along line W-W of  FIG.  1   , which shows an example of a sliding surface of a sliding component according to Embodiment 6 of the present invention; and 
         FIGS.  8 A to  8 D  are examples of a closed curve having a short axis and a long axis. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, modes for carrying out the present invention will be exemplified based on embodiments with reference to the drawings. However, unless otherwise specified, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments are not intended to limit the scope of the present invention. 
     Embodiment 1 
     A sliding component according to Embodiment 1 of the present invention will be described with reference to  FIGS.  1  and  2   . In the following embodiment, a mechanical seal, which is an example of a sliding component, will be described as an example. However, the present invention is not limited thereto, and for example, the present invention may be used as a sliding component of a bearing that slides on a rotation shaft while sealing lubricating oil on one side in an axial direction of a cylindrical sliding surface. An outer peripheral side of the sliding component constituting the mechanical seal will be described as a sealed fluid side (a high-pressure fluid side), and an inner peripheral side will be described as a leakage side (a low-pressure fluid side, for example, an atmosphere side). 
       FIG.  1    is a vertical cross-sectional view showing an example of a mechanical seal  1 , which belongs to an inside type in which sealed fluid leaking from an outer periphery of a sliding surface S toward an inner peripheral direction is sealed, and includes a rotation-side cartridge and a fixed-side cartridge. The rotation-side cartridge includes a sleeve  2  fitted to a rotation shaft  10 , an annular rotation-side sealing ring  3  that is one sliding component, and a packing  8  that seals space between the sleeve  2  and the rotation-side sealing ring  3 . The rotation-side cartridge rotates together with the rotation shaft  10 . 
     The fixed-side cartridge includes a housing  4  attached to a casing  9 , an annular fixed-side sealing ring  5  that is another sliding component, a bellows  7  that seals space between the fixed-side sealing ring  5  and the housing, and a coiled wave spring  6  that urges the fixed-side sealing ring  5  toward the rotation-side sealing ring  3  via the bellows  7 . The housing is fixed to the casing  9  in a rotation direction and an axial direction. 
     In the mechanical seal  1  having the above configuration, the sliding surface S of the rotation-side sealing ring  3  and the sliding surface S of the fixed-side sealing ring  5  slide relative to each other so as to prevent the sealed fluid from flowing out from the outer peripheral side to the inner peripheral side. Although  FIG.  1    shows a case where a width of the sliding surface of the rotation-side sealing ring  3  is wider than a width of the sliding surface of the fixed-side sealing ring  5 , the present invention is not limited thereto, and it is needless to say that the present invention may also be applied in an opposite case. 
     Materials of the rotation-side sealing ring  3  and the fixed-side sealing ring  5  are selected from silicon carbide (SiC) that has good wear resistance, carbon that has good self-lubricating performance, and the like. For example, both of the rotation-side sealing ring  3  and the fixed-side sealing ring  5  may be made of SiC, or the rotation-side sealing ring  3  may be made of SiC while the fixed-side sealing ring  5  is made of carbon. 
     As shown in  FIG.  2   , the sliding surface S of the fixed-side sealing ring  5  is partitioned into a predetermined number (six in the example of  FIG.  1   ) of regions  11  by land portions R provided from the sealed fluid side to the leakage side. Dimple groups  14  are arranged in the respective regions. Each dimple group  14  is formed by arranging a plurality of dimples  12 . In addition, an axis CL is a radial axis that divides each region  11  symmetrically in a left-tight direction. 
     In the present invention, each dimple  12  is a recess that includes an opening portion surrounded by the flat sliding surface S and a bottom portion that is recessed relative to the sliding surface S. An opening portion  12   a  of the dimple  12  has a shape having a long axis L and a short axis  1  orthogonal to each other. In addition, the dimples  12  are spaced apart from each other with the land portions R interposed therebetween. In the present invention, the long axis L is an imaginary straight line that passes through a centroid G of the shape of the opening portion  12   a  and connects maximum width portions of the opening portion  12   a . In addition, the short axis K is an imaginary straight line that passes through the centroid G and is orthogonal to the long axis L to connect the opening portion. In the present embodiment, as an example, the opening portion of the dimple  122  is an ellipse having the long axis L and the short axis K orthogonal to each other. However, the shape is not limited to the ellipse, and may also be an oval shape, a rhombus shape, a polygonal shape, or any shape formed by closed curves  91 ,  92 ,  93 , or  94  as shown in  FIGS.  8 A to  8 D , as long as the shape has the long axis and the short axis orthogonal to each other. 
     As shown in  FIG.  2   , the dimple group  14  is formed by arranging a predetermined number of sub dimple groups  14   a ,  14   b ,  14   c ,  14   d ,  14   e ,  14   f ,  14   g , and so on with the land portions R interposed therebetween in a. radial direction. In addition, the sub dimple groups  14   a ,  14   b ,  14   c ,  14   d ,  14   e ,  14   f ,  14   g , and so on are arranged so that the long axes L of the dimples  12  are aligned along corresponding one of imaginary curves  13  having a curvature different from a curvature of a circumference of the sliding surface S. That is, each sub dimple group has a shape in which the long axes L of the dimples  12  are aligned so as to be in contact with the imaginary curve  13 . The curve  13  is a curve that is convex toward the sealed fluid side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  14   a ,  14   b ,  14   c ,  14   d ,  14   e ,  14   f ,  14   g , and so on, the dimples  12  arranged in the vicinity of the axis CL are arranged to be closest to the sealed fluid side, and the dimples  12  arranged at both ends of the region  11  are arranged to be closest to the leakage side. In addition, the dimples  12  arranged at the both ends of each of the sub dimple groups  14   a ,  14   b ,  14   c ,  14   d ,  14   e ,  14   f ,  14   g , and so on may be arranged to be in contact with a leakage-side peripheral edge  5   a  or to be opened toward the leakage-side peripheral edge  5   a . Further, the sub dimple groups  14   a ,  14   b ,  14   c ,  14   d ,  14   e ,  14   f ,  14   g , and so on may be configured such that the dimples  12  are arranged symmetrically relative to the axis CL. Hereinafter, in the present invention, the circumference of the sliding surface S indicates a locus of points at an equal distance from a center C of the sliding surface S. 
     Although the long axes L of the dimples  12  are arranged close to each other and aligned such that the long axes L of the dimples  12  constituting the sub dimple group are in contact with the imaginary curve  13  in Embodiment 1, the long axes L of the dimples  12  may also be arranged to be inclined at a predetermined angle relative to the imaginary curve  13 . In addition, for the sake of explanation, reference numerals of the sub dimple groups  14   a ,  14   b ,  14   c ,  14   d ,  14   e ,  14   f , and  14   g  are shown only in a surrounding portion in  FIG.  2   . The number of sub dimple groups arranged in each region  11  is determined based on design conditions and the like. 
     When the rotation-side sealing ring  3  of the mechanical seal  1  configured as described above rotates in a counterclockwise direction as shown in  FIG.  2   , fluid between the sliding surfaces S and fluid in each dimple  12  are moved following a moving direction of the rotation-side sealing ring  3  due to viscosity of the fluid. Since a flow path of the fluid flowing into the dimple  12  rapidly expands, negative pressure is generated on an upstream side of the dimple  12 , and thus cavitation occurs. However, since a magnitude of the negative pressure in the cavitation is limited by a value of fluid vapor pressure, the negative pressure does not become large. In addition, on a downstream side of the dimple  12 , positive pressure (dynamic pressure effect) is generated by a wedge effect due to rapid contraction of a flow path. Due to the negative pressure generated on the upstream side of the dimple  12 , the dimple  12  exhibits a suction effect of suctioning surrounding fluid. On the other hand, since the positive pressure generated on the downstream side of the dimple  12  is larger than the negative pressure in the cavitation, the entire dimple  12  becomes positive pressure. Due to the positive pressure generated by the plurality of dimples  12  arranged in the sliding surface S, space between the sliding surfaces S is expanded, and thus the fluid flows onto the sliding surface S to exert a lubricating function. 
     When the dimples  12  are arranged from the leakage-side peripheral edge  5   a , to a sealed-fluid-side peripheral edge  5   b  of the sliding surface S, the dimple group  14  exhibits a pumping effect of suctioning the fluid onto the sliding surface from the leakage side, and thus a sealing effect is improved. In addition, since high-pressure fluid is suctioned from the sealed fluid side to supply the fluid pressurized by the dynamic pressure effect of the dimples  12  to the sliding surface, a fluid lubricating effect can be improved. In particular, when the dimples  12  are arranged to form the shape of the curve  13  that is convex toward the sealed. fluid side as in the sub dimple groups  14   a ,  14   b , and so on in  FIG.  2   , the sealing effect of the dimple group  14  is improved as compared with a dimple group in which dimples are arranged concentrically in a circumferential direction of the sliding surface S. 
     In addition, since each dimple  12  includes the elliptical opening portion  12   a  that has the long axis and the short axis orthogonal to each other, the suction effect and the dynamic pressure effect of the dimple  12  become different depending on inclination of the long axis L. When the long axis L of the dimple  12  is arranged along a circumferential direction, a fluid holding function of the dimple  12  is improved. When the long axis L of the dimple  12  is inclined by about 45° relative to a radial axis r, the suction effect is improved. In addition, when the long axis L of the dimple  12  is arranged along a radial direction, the dynamic pressure effect is improved. In this way, even when the dimple  12  has the same elliptical shape, the suction effect and the dynamic pressure effect may be increased or decreased by changing the inclination of the long axis L of the dimple  12 . 
     In addition, since the dimples  12  are arranged along the curve  13  in the sub dimple groups  14   a ,  14   b , and so on, an angle of the long axis L of each dimple  12  gradually changes along the curve  13 . As a result, since a direction of the long axis L of each dimple  12  gradually changes along the curve  13 , the sub dimple groups  14   a ,  14   b , and so on are constituted by dimples  12  having different suction effects and dynamic pressure effects. Even when the mechanical seal  1  is used in a wide rotation speed range, since the dimples  12  suitable for each rotation speed exhibit favorable suction effect and dynamic pressure effect, the dimple group  14  as a whole exhibits favorable sealing performance and lubricating function. 
     Further, the sub dimple groups  14   a ,  14   b , and so on are arranged substantially symmetrically relative to the axis CL along the curve  13  so as to be convex toward the sealed fluid side, and therefore, the sub dimple groups  14   a ,  14   b , and so on exhibit favorable sealing performance and lubricating function not only during forward rotation but also during reverse rotation. 
     As described above, the sliding component of the present invention has the following effects. 
     1. The dimples  12  constituting the dimple group  14  have negative pressure on the upstream side thereof so as to exhibit a fluid suctioning effect, and exhibit a lubricating function since fluid pressurized by a wedge effect on the downstream side is supplied to the sliding surface. 
     2. When the dimples  12  are arranged from the leakage-side peripheral edge  5   a  to the sealed-fluid-side peripheral edge  5   b  of the sliding surface S, the dimple group  14  exhibits a pumping effect of suctioning the fluid onto the sliding surface from the leakage side, and thus a sealing effect can be improved. In addition, since high-pressure fluid is suctioned from the sealed fluid side to supply the fluid pressurized by the dynamic pressure effect of the dimples  12  to the sliding surface, a fluid lubricating effect can be improved. 
     3. When the dimples  12  are arranged to form the shape of the curve  13  that is convex toward the sealed fluid side as in the sub dimple groups  14   a ,  14   b , and so on in  FIG.  2   , the sealing effect of the dimple group  14  can be improved as compared with a dimple group in which dimples are arranged concentrically in a circumferential direction of the sliding surface S. 
     4. Since each dimple  12  includes the elliptical opening portion  12   a  that has the long axis and the short axis orthogonal to each other, strength of the suction effect and the dynamic pressure effect of the dimple  12  can be changed by changing the inclination of the long axis L. As a result, even when the dimple  12  has the same elliptical shape, the suction effect and the dynamic pressure effect can be improved by changing the inclination of the long axis L of the dimple  12 . 
     5. Since the dimples  12  are arranged along the curve  13  in the sub dimple groups  14   a ,  14   b , and so on, the angle of the long axis L of each dimple  12  gradually changes along the curve  13 . As a result, since the direction of the long axis L of each dimple  12  gradually changes along the curve  13 , the sub dimple groups  14   a ,  14   b , and so on are constituted by dimples  12  having different suction effects and dynamic pressure effects. Even when the mechanical seal  1  is used in a wide rotation speed range, since the dimples  12  suitable for each rotation speed exhibit favorable suction effect and dynamic pressure effect, the dimple group  14  as a whole exhibits favorable sealing performance and lubricating function, 
     6. The sub dimple group  14  is arranged substantially symmetrically relative to the axis CL so as to form the curve  13  that is convex toward the sealed fluid side, and therefore, the sub dimple group  14  exhibits favorable suction effect and dynamic pressure effect not only during forward rotation but also during reverse rotation. 
     Embodiment 2 
     A sliding component according to Embodiment 2 of the present invention will be described.  FIG.  3    shows the sliding surface S of the sliding component according to Embodiment 2 in which sub dimple groups  24   a ,  24   b , and so on are arranged along a curve  23  that is convex toward the leakage side, which is different from Embodiment 1. Other configurations are the same as those of Embodiment 1. Hereinafter, the same members and configurations as those of Embodiment 1 will be denoted by the same reference numerals, and redundant description thereof will be omitted. 
     As shown in  FIG.  3   , the sliding surface S of the fixed-side sealing ring  5  is partitioned into a predetermined number (six in the example of  FIG.  3   ) of regions  21  by the land portions R provided from the sealed fluid side to the leakage side. Dimple groups  24  are arranged in the respective regions. Each dimple group  24  is formed by arranging a plurality of dimples  22 . In addition, the axis CL is a radial axis that divides each region  21  symmetrically in the left-right direction. 
     As shown in  FIG.  3   , the dimple group  24  is formed by arranging a predetermined number of sub dimple groups  24   a ,  24   b ,  24   c ,  24   d ,  24   e ,  24   f ,  24   g , and so on with the land portions R interposed therebetween in the radial direction. The sub dimple groups  24   a ,  24   b ,  24   c ,  24   d ,  24   e ,  24   f ,  24   g , and so on are arranged such that the long axes L of the dimples  22  are aligned to form the imaginary curve  23  having a curvature different from the curvature of the circumference of the sliding surface S. That is, each sub dimple group has a shape in which the long axes L of the dimples  22  are aligned so as to be in contact with the imaginary curve  23 . The curve  23  is a curve that is convex toward the leakage side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  24   a ,  24   b ,  24   c ,  24   d ,  24   e ,  24   f ,  24   g , and so on, the dimples  22  arranged in the vicinity of the axis CL are arranged closest to the leakage side, and the dimples  22  arranged at both ends are arranged closest to the sealed fluid side. In addition, the dimples  22  arranged at both ends of each of the sub dimple groups  24   a ,  24   b ,  24   c ,  24   d ,  24   e ,  24   f ,  24   g , and so on may be arranged to be in contact with the sealed-fluid-side peripheral edge  5   b  or to be opened toward the sealed-fluid-side peripheral edge  5   b . Further, the sub dimple groups  24   a ,  24   b ,  24   c ,  24   d ,  24   e ,  24   f ,  24   g , and so on may be configured such that the dimples  22  are arranged symmetrically relative to the axis CL. For the sake of explanation, reference numerals of the sub dimple groups  24   a ,  24   b ,  24   c ,  24   d ,  24   e , and  24   f  are shown only in a surrounding portion in  FIG.  3   . The number of sub dimple groups arranged in each region  21  is determined base on design conditions and the like. 
     When the dimples  22  are arranged close to each other and along the curve  23  as in the sub dimple groups  24   a ,  24   b , and so on, suction and discharge are continuously repeated between the adjacent dimples  22 . Therefore, when the dimples  22  are arranged from the leakage-side peripheral edge  5   a  to the sealed-fluid-side peripheral edge  5   b  of the sliding surface S, the dimple group  24  exhibits a pumping effect of suctioning the fluid onto the sliding surface from the leakage side, and thus leakage can be reduced. In addition, since high-pressure fluid is suctioned from the sealed fluid side and fluid pressurized by a dynamic pressure effect of each dimple  22  is supplied to the sliding surface, a fluid lubricating effect can be improved. In particular, as shown in  FIG.  3   , when the dimples  22  are arranged along the curve  23  that is convex toward the leakage side as in the sub dimple groups  24   a ,  24   b , and so on, the fluid lubricating effect of the dimple group  24  can be stronger than a sealing effect thereof. 
     In addition, since the dimples  22  are arranged along the curve  23  in the sub dimple groups  24   a ,  24   b , and so on, the angle of the long axis L of each dimple  22  gradually changes along the curve  23 , and thus a suction effect and the dynamic pressure effect of each dimple also gradually change along the curve  23 . That is, since the dimples  22  having different suction effects and dynamic pressure effects are arranged in the sub dimple groups  24   a ,  24   b , and so on, even when used in a wide rotation speed range, there are dimples  22  exhibiting favorable suction effect and dynamic pressure effect at each rotation speed. By arranging the dimple group  24  in which the plurality of sub dimple groups  24   a ,  24   b , and so on are arranged in the radial direction in each region  21  of the sliding surface, the dimple group  24  as a whole exhibits a lubricating function even when used in a wide rotation speed range. 
     Further, the sub dimple groups  24   a ,  24   b , and so on are arranged substantially symmetrically relative to the axis CL so as to form the curve  23  that is convex toward the sealed fluid side, and therefore, the sub dimple groups  24   a ,  24   b , and so on exhibit a favorable lubricating function not only during forward rotation but also during reverse rotation. 
     As described above, the sliding component of Embodiment 2 has the following effects. 
     1. The dimples  22  constituting the dimple group  24  have negative pressure on an upstream side thereof so as to exhibit a fluid suctioning function, and exhibit a lubricating function by discharging fluid pressurized by a wedge effect on a downstream side. 
     2. When the dimples  22  are arranged from the leakage-side peripheral edge  5   a  to the sealed-fluid-side peripheral edge  5   b  of the sliding surface S, the dimple group  24  exhibits a pumping effect of suctioning the fluid onto the sliding surface from the leakage side, and thus leakage can be reduced. In addition, since high-pressure fluid is suctioned from the sealed fluid side and fluid pressurized by the dynamic pressure effect of each dimple  22  is supplied to the sliding surface, a fluid lubricating effect can be improved. 
     3. When the dimples  22  are arranged to form the shape of the curve  23  that is convex toward the leakage side as in the sub dimple groups  24   a ,  24   b , and so on in  FIG.  3   , the fluid lubricating effect of the dimple group  24  can be improved as compared with a dimple group in which dimples are arranged concentrically in the circumferential direction of the sliding surface S. 
     4. Since each dimple  22  includes an elliptical opening portion  22   a  that has the long axis and the short axis orthogonal to each other, strength of the suction effect and the dynamic pressure effect of the dimple  22  can be changed by changing the inclination of the long axis L. As a result, even when the dimple  22  has the same elliptical shape, the suction effect and the dynamic pressure effect can be improved by changing the inclination of the long axis L of the dimple  22 . 
     5. Since the dimples  22  are arranged along the curve  23  in the sub dimple groups  24   a ,  24   b , and so on, the angle of the long axis L of each dimple  22  gradually changes along the curve  23 , and thus the suction effect and the dynamic pressure effect of each dimple also gradually change along the curve  23 . That is, since the dimples  22  having different suction effects and dynamic pressure effects are arranged in the sub dimple groups  24   a ,  24   b , and so on, even when used in a wide rotation speed range, there are dimples  22  exhibiting favorable suction effect and dynamic pressure effect at each rotation speed. By arranging the dimple group  24  in which the plurality of sub dimple groups  24   a ,  24   b , and so on are arranged in the radial direction in each region  21  of the sliding surface, the dimple group  24  as a whole exhibits a lubricating function even when used in a wide rotation speed range. 
     6. The sub dimple groups  24   a ,  24   b , and so on are arranged substantially symmetrically relative to the axis CL so as to form the curve  23  that is convex toward the sealed fluid side, and therefore, the sub dimple groups  24   a ,  24   b , and so on exhibit a favorable lubricating function not only during forward rotation but also during reverse rotation. 
     Embodiment 3 
     A sliding product according to Embodiment 3 of the present invention will be described.  FIG.  4    shows the sliding surface S of a sliding component according to Embodiment 3 in which a dimple group  34  is arranged such that the short axes K of adjacent dimples  32  are arranged close to each other and aligned to form a curve  33  that is convex toward the sealed fluid side, which is different from Embodiment 1. Other configurations are the same as those of Embodiment 1. Hereinafter, the same members and configurations as those of Embodiment 1 will be denoted by the same reference numerals, and redundant description thereof will be omitted. 
     As shown in  FIG.  4   , the sliding surface S of the fixed-side sealing ring  5  is partitioned into a predetermined number (six in the example of  FIG.  4   ) of regions  31  by the land portions R provided from the sealed fluid side to the leakage side. The dimple groups  34  are arranged in the respective regions. Each dimple group  34  is formed by arranging a plurality of the dimples  32 . In addition, the axis CL is a radial axis that divides each region  31  symmetrically in the left-right direction. 
     As shown in  FIG.  4   , the dimple group  34  is formed by arranging a predetermined number of sub dimple groups  34   a ,  34   b ,  34   c ,  34   d ,  34   e ,  34   f ,  34   g , and so on with the land portions R interposed therebetween in the radial direction. The sub dimple groups  34   a ,  34   b ,  34   c ,  34   d ,  34   e ,  34   f ,  34   g , and so on are arranged such that the short axes K of the dimples  32  are aligned to form the imaginary curve  33  having a curvature different from the curvature of the circumference of the sliding surface S. That is, each sub dimple group has a shape in which the short axes K of the dimples  32  are aligned so as to be in contact with the imaginary curve  33 . The curve  33  is a curve that is convex toward the sealed fluid side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  34   a ,  34   b ,  34   c ,  34   d ,  34   e ,  34   f ,  34   g , and so on, the dimples  32  arranged in the vicinity of the axis CL are arranged closest to the sealed fluid side, and the dimples  32 . arranged at both ends are arranged closest to the leakage side. In addition, the dimples  12  arranged at both ends of each of the sub dimple groups  34   a ,  34   b ,  34   c ,  34   d ,  34   e ,  34   f ,  34   g , and so on may be arranged to be in contact with the leakage-side peripheral edge  5   a  or to be opened toward the leakage-side peripheral edge  5   a . Further, the sub dimple groups  34   a ,  34   b ,  34   c ,  34   d ,  34   e ,  34   f ,  34   g , and so on may be configured such that the dimples  32  are arranged symmetrically relative to the axis CL. Here, the curve  33  is an imaginary curve that is in contact with the short axis K of each dimple  32 . For the sake of explanation, reference numerals of the sub dimple groups  34   a ,  34   b ,  34   c ,  34   d ,  34   e ,  34   f , and  34   g  are shown only in a surrounding portion in  FIG.  4   . The number of sub dimple groups arranged in each region  31  is determined base on design conditions and the like. 
     In Embodiment 3, a dynamic pressure effect of the dimple  32  can be better than a sealing effect thereof by arranging the long axes L of the dimples  32  in the radial direction. As a result, a lubricating effect of the sliding surface S as a whole can be improved, and thus sliding torque can be reduced. 
     In addition, when the dimples  32  are arranged to form a shape of the curve  33  that is convex toward the sealed fluid side as in the sub dimple groups  34   a ,  34   b , and so on in  FIG.  4   , a sealing effect of the dimple group  34  can be improved as compared with a dimple group in which dimples are arranged concentrically in the circumferential direction of the sliding surface S. 
     In addition, since the dimples  32  are arranged along the curve  33  in the sub dimple groups  34   a ,  34   b , and so on, an angle of the short axis K of each dimple  32  gradually changes along the curve  33 . As a result, a suction effect and the dynamic pressure effect of each dimple  32  gradually change along the curve  33 . That is, since the dimples  32  exhibiting different suction effects and dynamic pressure effects are arranged in the sub dimple groups  34   a ,  34   b , and so on, even when used in a wide rotation speed range, there are dimples  32  exhibiting favorable suction effect and dynamic pressure effect at each rotation speed. By arranging the dimple group  34  in which the plurality of sub dimple groups  34   a ,  34   b , and so on are arranged in the radial direction in each region  31  of the sliding surface, the dimple group  34  as a whole exhibits favorable sealing performance and lubricating function even when used in a wide rotation speed range. 
     Further, the sub dimple groups  34   a ,  34   b , and so on are arranged substantially symmetrically relative to the axis CL so as to form the curve  33  that is convex toward the sealed fluid side, and therefore, the sub dimple groups  34   a ,  34   b , and so on exhibit favorable sealing performance and lubricating function not only during forward rotation but also during reverse rotation. 
     As described above, the sliding component of Embodiment 3 has the following effects in addition to the effects of Embodiment 1. 
     1. The dynamic pressure effect of the dimple  32  can be better than the sealing effect thereof by arranging the long axes L of the dimples  32  in the radial direction. As a result, the lubricating effect of the sliding surface S as a whole can be improved, and thus sliding torque can be reduced. 
     2. When the dimples  32  are arranged to form the shape of the curve  33  that is convex toward the sealed fluid side as in the sub dimple groups  34   a ,  34   b , and so on in  FIG.  4   , the sealing effect of the dimple group  34  can be improved as compared with a dimple group in which dimples are arranged concentrically in the circumferential direction of the sliding surface S. 
     Embodiment 4 
     A slidingproduct according to Embodiment 4 of the present invention will described.  FIG.  5    shows the sliding surface S of a sliding component according to Embodiment 4 in which a dimple group  44  is arranged such that the short axes K of adjacent dimples  42  are arranged close to each other and aligned to form a curve  43  that is convex toward the leakage side, which is different from Embodiment 1. Other configurations are the same as those of Embodiment 1. Hereinafter, the same members and configurations as those of Embodiment 1 will be denoted by the same reference numerals, and redundant description thereof will be omitted. 
     As shown in  FIG.  5   , the sliding surface S of the fixed-side sealing ring  5  is partitioned into a predetermined number (six in the example of  FIG.  5   ) of regions  41  by the land portions R provided from the sealed fluid side to the leakage side. The dimple groups  44  are arranged in the respective regions. Each dimple group  44  is formed by arranging a plurality of the dimples  42 . In addition, the axis CL is a radial axis that divides each region  41  symmetrically in the left-right direction, 
     As shown in  FIG.  5   , the dimple group  44  is formed by arranging a predetermined number of sub dimple groups  44   a ,  44   b ,  44   c ,  44   d ,  44   e ,  44   f ,  44   g , and so on with the land portions R interposed therebetween in the radial direction. The sub dimple groups  44   a ,  44   b ,  44   c ,  44   d ,  44   e ,  44   f ,  44   g , and so on are arranged such that the short axes K of the dimples  42  are aligned to form the imaginary curve  43  having a curvature different from the curvature of the circumference of the sliding surface S. That is, each sub dimple group has a shape in which the short axes K of the dimples  42  are aligned so as to be in contact with the imaginary curve  43 . The curve  43  is a curve that is convex toward the leakage side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  44   a ,  44   b ,  44   c ,  44   d ,  44   e ,  44   f ,  44   g , and so on, the dimples  42  arranged in the vicinity of the axis CL are arranged closest to the leakage side, and the dimples  42  arranged at both ends are arranged closest to the sealed fluid side. In addition, the dimples  42  arranged at both ends of each of the sub dimple groups  44   a ,  44   b ,  44   c ,  44   d ,  44   e ,  44   f ,  44   g , and so on may be arranged to be in contact with the sealed-fluid-side peripheral edge  5   b  or to be opened toward the sealed-fluid-side peripheral edge  5   b . Further, the sub dimple groups  44   a ,  44   b ,  44   c ,  44   d ,  44   e ,  44   f ,  44   g , and so on may be configured such that the dimples  42  are arranged symmetrically relative to the axis CL. For the sake of explanation, reference numerals of the sub dimple groups  44   a ,  44   b ,  44   c ,  44   d ,  44   e ,  44   f , and  44   g  are shown only in a surrounding portion in  FIG.  5   . The number of sub dimple groups arranged in each region  41  is determined base on design conditions and the like. 
     A dynamic pressure effect of the dimple  42  can be better than a sealing effect thereof by arranging the long axes L of the dimples  42  in the radial direction. As a result, the lubricating effect of the sliding surface S as a whole can be improved, and thus sliding torque can be reduced. 
     When the dimples  42  are arranged to form a shape of the curve  43  that is convex toward the leakage side as in the sub dimple groups  44   a ,  44   b , and so on in  FIG.  5   , a fluid lubricating effect of the dimple group  44  can be improved as compared with a dimple group in which dimples are arranged concentrically in the circumferential direction of the sliding surface S. 
     In addition, since the dimples  42  are arranged along the curve  43  in the sub dimple groups  44   a ,  44   b , and so on, the angle of the long axis L of each dimple  42  gradually changes along the curve  43 . As a result, a suction effect and the dynamic pressure effect of each dimple  42  gradually change along the curve  43 . That is, since the dimples  42  exhibiting different suction effects and dynamic pressure effects are arranged in the sub dimple groups  44   a ,  44   b , and so on, even when used in a wide rotation speed range, there are dimples  42  exhibiting favorable suction effect and dynamic pressure effect at each rotation speed. By arranging the dimple group  44  in which the plurality of sub dimple groups  44   a ,  44   b , and so on are arranged in the radial direction in each region  41  of the sliding surface, the dimple group  44  as a whole exhibits favorable sealing performance and lubricating function even when used in a wide rotation speed range. 
     Further, the sub dimple groups  44   a ,  44   b , and so on are arranged substantially symmetrically relative to the axis CL so as to form the curve  43  that is convex toward the leakage side, and therefore, the sub dimple groups  44   a ,  44   b , and so on exhibit favorable sealing performance and lubricating function not only during forward rotation but also during reverse rotation. 
     As described above, the sliding component of Embodiment 4 has the following effects in addition to the effects of Embodiment 2. 
     1. The dynamic pressure effect of the dimple  42  can be better than the sealing effect thereof by arranging the long axes L of the dimples  42  in the radial direction. As a result, the lubricating effect of the sliding surface S as a whole can be improved, and thus sliding torque can be reduced. 
     2. When the dimples  42  are arranged to form the shape of the curve  43  that is convex toward the leakage side as in the sub dimple groups  44   a ,  44   b , and so on in  FIG.  5   , the fluid lubricating effect of the dimple group  44  can be improved as compared with a dimple group in which dimples are arranged concentrically in the circumferential direction of the sliding surface S. 
     Embodiment 5 
     A sliding product according to Embodiment 5 of the present invention will be described.  FIG.  6    shows the sliding surface S of a sliding component according to Embodiment 5 in which a dimple group  54  arranged to form a curve  53  that is convex toward the sealed fluid side on the leakage side and a dimple group  59  arranged to form a curve  58  that is convex toward the leakage side on the sealed fluid are provided, which is different from Embodiment 1. Other configurations are the same as those of Embodiment 1. Hereinafter, the same members and configurations as those of Embodiment 1 will be denoted by the same reference numerals, and redundant description thereof will be omitted, 
     As shown in  FIG.  6   , the sliding surface S of the fixed-side sealing ring  5  is partitioned into a predetermined number (six in the example of  FIG.  6   ) of regions  51  by the land portions R provided from the sealed fluid side to the leakage side. The dimple groups  54  and  59  are arranged in the respective regions. Each dimple group  54  is formed by arranging a plurality of dimples  52 , and each dimple group  59  is formed by arranging a plurality of dimples  57 . In addition, the axis CL is a radial axis that divides each region  51  symmetrically in the left-right direction. 
     The dimple group  54  is arranged on the leakage side of the sliding surface S. The dimple group  54  is formed by arranging a predetermined number of sub dimple groups  54   a ,  54   b ,  54   c ,  54   d , and so on with the land portions R interposed therebetween in the radial direction, In addition, the sub dimple groups  54   a ,  54   b ,  54   c ,  54   d , and so on are arranged such that the long axes L of the dimples  52  are aligned to form the imaginary curve  53  having a curvature different from the curvature of the circumference of the sliding surface S. That is, each sub dimple group has a shape in which the long axes L of the dimples  52  are aligned so as to be in contact with the imaginary curve  53 . The curve  53  is a curve that is convex toward the sealed fluid side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  54   a ,  54   b ,  54   c ,  54   d , and so on, the dimples  52  arranged in the vicinity of the axis CL are arranged closest to the sealed fluid side, and the dimples  52  arranged at both ends far from the axis CL are arranged closest to the leakage side. In addition, the dimples  52  arranged at both ends of each of the sub dimple groups  54   a ,  54   b ,  54   c ,  54   d , and so on may be arranged to be in contact with the leakage-side peripheral edge  5   a  or to be opened toward the leakage-side peripheral edge  5   a . Further, the sub dimple groups  54   a ,  54   b ,  54   c ,  54   d , and so on may be configured such that the dimples  52  are arranged symmetrically relative to the axis CL. For the sake of explanation, reference numerals of the sub dimple groups  54   a ,  54   b ,  54   c , and  54   d  are shown only in a surrounding portion in  FIG.  6   . The number of sub dimple groups arranged in each region  51  is determined base on design conditions and the like. 
     The dimple group  59  is arranged on the sealed fluid side of the sliding surface S. The dimple group  59  is formed by arranging a predetermined number of sub dimple groups  59   a ,  59   b ,  59   c , and so on with the land portions R interposed therebetween in the radial direction. The sub dimple groups  59   a ,  59   b ,  59   c , and so on are arranged such that the long axes L of the dimples  57  are aligned to form the imaginary curve  58  having a curvature different from the curvature of the circumference of the sliding surface S. That is, each sub dimple group has a shape in which the long axes L of the dimples  57  are aligned so as to be in contact with the imaginary curve  58 . The curve  58  is a curve that is convex toward the leakage side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  59   a ,  59   b ,  59   c , and so on, the dimples  57  arranged in the vicinity of the axis CL are arranged closest to the leakage side, and the dimples  57  arranged at both ends are arranged closest to the sealed fluid side. In addition, the dimples  57  arranged at both ends of each of the sub dimple groups  59   a ,  59   b ,  59   c , and so on may be arranged to be in contact with the sealed-fluid-side peripheral edge  5   b  or to be opened toward the sealed-fluid-side peripheral edge  5   b . Further, the sub dimple groups  59   a ,  59   b ,  59   c , and so on may be configured such that the dimples  57  are arranged symmetrically relative to the axis CL. For the sake of explanation, reference numerals of the sub dimple groups  59   a ,  59   b , and  59   c  are shown only in a surrounding portion in  FIG.  6   . 
     The dimple group  54  that is provided on the leakage side of the sliding surface S and arranged to form the curve  53  that is convex toward the sealed fluid side exhibits better sealing performance than dimples arranged concentrically in the circumferential direction of the sliding surface S. In addition, the dimple group  59  that is provided on the sealed fluid side of the sliding surface S and arranged to form the curve  58  that is convex toward the leakage side of the sliding surface S exhibits a better lubricating effect than dimples arranged concentrically in the circumferential direction of the sliding surface S. By arranging the dimple group  54  having excellent sealing performance and the dimple group  59  having excellent lubricating performance on the sliding surface S in this manner, the mechanical seal  1  can exhibit excellent sealing performance and lubricating performance. 
     Since the dimple group  54  is arranged substantially symmetrically relative to the axis CL so as to form the curve  53  that is convex toward the sealed fluid side, the dimple group  54  can exhibit favorable sealing performance not only during forward rotation but also during reverse rotation. In addition, since the dimple group  59  is arranged substantially symmetrically relative to the axis CL so as to form the curve  58  that is convex toward the leakage side, the dimple group  59  exhibits a lubricating function not only during forward rotation but also during reverse rotation, and thus can exhibit favorable sealing performance and lubricating performance regardless of a rotation direction thereof. 
     As described above, the sliding component of Embodiment 5 has the following effects in addition to the effects of Embodiments 1 and 2. 
     1. The dimple group  54  that is provided on the leakage side of the sliding surface S and arranged to form the curve  53  that is convex toward the sealed fluid side exhibits better sealing performance than dimples arranged concentrically in the circumferential direction of the sliding surface S. In addition, the dimple group  59  that is provided on the sealed fluid side of the sliding surface S and arranged to form the curve  58  that is convex toward the leakage side of the sliding surface S exhibits a better lubricating effect than dimples arranged concentrically in the circumferential direction of the sliding surface S. 
     2. Since the dimple group  54  is arranged substantially symmetrically relative to the axis CL while the dimple group  59  is arranged substantially symmetrically relative to the axis CL, favorable sealing performance and lubricating performance can be exhibited regardless of rotation directions. 
     Embodiment 6 
     A sliding product according to Embodiment 6 of the present invention will be described.  FIG.  7    shows the sliding surface S of a sliding component according to Embodiment 6 in which a groove portion is provided between a dimple group  64  arranged to form a curve  63  that is convex toward the sealed fluid side on the leakage side and a dimple group  69  arranged to form a curve  68  that is convex toward the leakage side on the sealed fluid, which is different from Embodiment 5. Other configurations are the same as those of Embodiment 5. Hereinafter, the same members and configurations as those of Embodiment 5 will be denoted by the same reference numerals, and redundant description thereof will be omitted. 
     As shown in  FIG.  7   , the sliding surface S of the fixed-side sealing ring  5  is partitioned into a predetermined number (six in the example of  FIG.  7   ) of regions  61  by the land portions R provided from the sealed fluid side to the leakage side. The dimple groups  64  and  69  are arranged in the respective regions. Each dimple group  64  is formed by arranging a plurality of dimples  62 , and each dimple group  69  is formed by arranging a plurality of dimples  67 . In addition, the axis CL is a radial axis that divides each region  61  symmetrically in the left-right direction. 
     As in Embodiment 5, the dimple group  64  arranged to form the curve  63  that is convex toward the sealed fluid side is arranged on the leakage side of the sliding surface S. The dimple group  64  is formed by arranging a predetermined number of sub dimple groups  64   a ,  64   b ,  64   c ,  64   d , and so on with the land portions R interposed therebetween in the radial direction. The sub dimple groups  64   a ,  64   b ,  64   c ,  64   d , and so on are arranged such that the long axes L of the dimples  62  are aligned to form the imaginary curve  63  having a curvature different from the curvature of the circumference of the sliding surface S. The curve  63  is a curve that is convex toward the sealed fluid side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  64   a ,  64   b ,  64   c ,  64   d , and so on, the dimples  62  arranged in the vicinity of the axis CL are arranged closest to the sealed fluid side, and the dimples  62  arranged at both ends are arranged closest to the leakage side. In addition, the dimples  62  arranged at both ends of each of the sub dimple groups  64   a ,  64   b ,  64   c ,  64   d , and so on may be arranged to be in contact with the leakage-side peripheral edge  5   a  or to be opened toward the leakage-side peripheral edge  5   a . Further, the sub dimple groups  64   a ,  64   b ,  64   c ,  64   d , and so on may be configured such that the dimples  62  are arranged symmetrically relative to the axis CL. For the sake of explanation, reference numerals of the sub dimple groups  64   a ,  64   b ,  64   c , and  64   d  are shown only in a surrounding portion in  FIG.  7   . The number of sub dimple groups arranged in each region  61  is determined based on design conditions and the like. 
     As in Embodiment 5, the dimple group  69  arranged to form the curve  68  that is convex toward the leakage side is arranged on the sealed fluid side of the sliding surface S. The dimple group  69  is formed by arranging a predetermined number of sub dimple groups  69   a ,  69   b .  69   c , and so on with the land portions R interposed therebetween in the radial direction. The sub dimple groups  69   a ,  69   b ,  69   c , and so on are arranged such that the long axes L of the dimples  67  are aligned to form the imaginary curve  68  having a curvature different from the curvature of the circumference of the sliding surface S. The curve  68  is a curve that is convex toward the leakage side, and is formed of an arc, a parabola, a sine wave, a cycloid curve, or the like that has the curvature different from the curvature of the circumference of the sliding surface S. In addition, in the sub dimple groups  69   a ,  69   b ,  69   c , and so on, the dimples  57  arranged in the vicinity of the axis CL are arranged closest to the leakage side, and the dimples  67  arranged at both ends are arranged closest to the sealed fluid side. In addition, the dimples  67  arranged at both ends of each of the sub dimple groups  69 a,  69   b ,  69   c , and so on may be arranged to be in contact with the sealed-fluid-side peripheral edge  5   b  or to be opened toward the sealed-fluid-side peripheral edge  5   b . Further, the sub dimple groups  69   a ,  69   b ,  69   c , and so on may be configured such that the dimples  67  are arranged symmetrically relative to the axis CL. For the sake of explanation, reference numerals of the sub dimple groups  69   a ,  69   b , and  69   c  are shown only in the surrounding portion in  FIG.  7   . 
     A groove portion  65  is provided between the dimple group  64  and the dimple group  69 . The groove portion  65  is formed to be sufficiently deeper than depths of the dimples  62  constituting the dimple group  64  and the dimples  67  constituting the dimple group  69 , and to be sufficiently larger than sizes of opening portions of the dimples  62  and the dimples  67 . 
     The dimple group  64  that is provided on the leakage side of the sliding surface S and arranged to form the curve  63  that is convex toward the sealed fluid side suctions fluid from the leakage side, and thus exhibits favorable sealing performance. In addition, the dimple group  69  that is provided on the sealed fluid side of the sliding surface S and arranged so as to form the curve  68  that is convex toward the leakage side of the sliding surface S suctions fluid from the sealed fluid side and discharges pressurized fluid from the inside of the dimples  67  to the sliding surface S, and thus the sliding surface S can be maintained in a fluid lubricating state. By arranging the dimple group  64  having excellent sealing performance and the dimple group  69  having excellent lubricating performance on the sliding surface S in this manner, the mechanical seal  1  can exhibit excellent sealing performance and lubricating performance. 
     In addition, since the groove portion  65  is provided between the dimple group  64  and the dimple group  69 , interference between the dimple group  64  and the dimple group  69  can be prevented. As a result, it is possible to prevent functions of the dimple group  64  that exhibits sealing performance and the dimple group  69  that exhibits lubricating performance from cancelling out each other in a region where the dimple group  64  and the dimple group  69  are close to each other. 
     The dimple group  64  is arranged substantially symmetrically relative to the axis CL so as to form the curve  63  that is convex toward the sealed fluid side, and therefore, the dimple group  64  exhibits favorable sealing performance not only during forward rotation but also during reverse rotation. Since the dimple group  69  is arranged substantially symmetrically relative to the axis CL so as to form the curve  68  that is convex toward the leakage side, the dimple group  69  exhibits a lubricating function not only during forward rotation but also during reverse rotation, and thus can exhibit favorable sealing performance and lubricating performance regardless of a rotation direction thereof. 
     As described above, the sliding component of Embodiment 6 has the following effects in addition to the effects of Embodiment 5. 
     In the mechanical seal of Embodiment 6, since the groove portion  65  is provided between the dimple group  64  and the dimple group  69 , interference between the dimple group  64  and the dimple group  69  can be prevented. Asa result, it is possible to prevent the functions of the dimple group  64  that exhibits sealing performance and the dimple group  69  that exhibits lubricating performance from cancelling out each other in the region where the dimple group  64  and the dimple group  69  are close to each other. 
     Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and changes and additions without departing from the spirit of the present invention are also included in the present invention. 
     Although the outer peripheral side is the sealed fluid side while the inner peripheral side is the leakage side in the above embodiment, the present invention is not limited thereto, and the present invention is also applicable to a case where the inner peripheral side is the sealed fluid side while the outer peripheral side is the leakage side. 
     REFERENCE SIGNS LIST 
       1  mechanical seal 
       2  sleeve 
       3  rotation-side sealing ring 
       4  housing 
       5  fixed-side sealing ring 
       6  coiled wave spring 
       7  bellows 
       8  packing 
       9  casing 
       10  rotation shaft 
       11  region 
       12  dimple 
       14  dimple group 
       14   a  sub dimple group 
       14   b  sub dimple group 
       14   c  sub dimple group 
       14   d  sub dimple group 
       14   e  sub dimple group 
       14   f  sub dimple group 
       14   g  sub dimple group 
       21  region 
       22  dimple 
       24  dimple group 
       24   a  sub dimple group 
       24   b  sub dimple group 
       24   c  sub dimple group 
       24   d  sub dimple group 
       24   e  sub dimple group 
       24   f  sub dimple group 
       31  region 
       32  dimple 
       34  dimple group 
       34   a  sub dimple group 
       34   b  sub dimple group 
       34   c  sub dimple group 
       34   d  sub dimple group 
       34   e  sub dimple group 
       34   f  sub dimple group 
       34   g  sub dimple group 
       41  region 
       42  dimple 
       44  dimple group 
       44   a  sub dimple group 
       44   b  sub dimple group 
       44   c  sub dimple group 
       44   d  sub dimple group 
       44   e  sub dimple group 
       44   f  sub dimple group 
       44   g  sub dimple group 
       51  region 
       52  dimple 
       54  dimple group 
       54   a  sub dimple group 
       54   b  sub dimple group 
       54   c  sub dimple group 
       54   d  sub dimple group 
       57  dimple 
       59  dimple group 
       59   a  sub dimple group 
       59   b  sub dimple group 
       59   c  sub dimple group 
       61  region 
       62  dimple 
       64  dimple group 
       64   a  sub dimple group 
       64   b  sub dimple group 
       64   c  sub dimple group 
       64   d  sub dimple group 
       65  groove portion 
       67  dimple 
       69  dimple group 
       69   a  sub dimple group 
       69   b  sub dimple group 
       69   c  sub dimple group 
     K short axis 
     L long axis 
     R land portion 
     S sliding surface 
     θ dimple angle