Patent Description:
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 <NUM>).

In addition, it is also known that dimples each including an elongated track-shaped opening portion 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 <NUM> ≤ L1 / L2 ≤ <NUM>, thereby optimally adjusting sealing performance and sliding torque of the dimples as a whole (see, for example, Patent Literature <NUM>).

<CIT> relates to a sealing device, according to the preamble of claim <NUM>, forming at least two dimples in a circumferential direction in each of a plurality of rows arranged in a radial direction on a sealing surface of a stationary-side sealing element or a rotating-side sealing element. Each dimple is tilted by a dimple angle θ between <NUM>° and <NUM>°, exclusive, such that the tip of that dimple in the direction of rotation is tilted toward the inner periphery side.

<CIT> and <CIT> show further examples of seal units.

In the technique of Patent Literature <NUM>, even though favorable sealing performance 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 the technique of Patent Literature <NUM>, 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.

An object of the present invention is, in a pair of sliding components that relatively slide on sliding surfaces, to provide the sliding components are capable of achieving favorable sealing performance and low sliding torque and when used in a wide rotation speed range.

In order to solve the above problem, a sliding component of the present invention is:.

The sliding component according to the present invention is characterized in that
the dimple angle changes at a constant rate in the radial direction.

According to this feature, by changing the dimple angle of the dimples constituting the dimple group at the constant rate in the radial direction, the suction effect and the dynamic pressure effect of the dimples may be changed in the radial direction.

The sliding component according to the present invention is characterized in that
the dimple angle discontinuously changes in the radial direction.

According to this feature, by discontinuously changing the dimple angle in the radial direction, the suction effect and the dynamic pressure effect of the dimples constituting the dimple group may be discontinuously changed in the radial direction, and thus a dimple group suitable for operating conditions in a specific range may be arranged.

The sliding component according to the present invention is characterized in that
a rate of change in the dimple angle in the radial direction changes in the radial direction.

According to this feature, by changing, in the radial direction, the rate of change in the dimple angle in the radial direction, dimples suitable for respective use conditions may be easily arranged in the radial direction.

The sliding component according to the present invention is characterized in that
the dimple angle is larger on a leakage side of the sliding surface and smaller on a sealed fluid side of the sliding surface.

According to this feature, since the dimple angle of the dimples arranged on the leakage side is large, the suction effect becomes predominant, and thus the dimples may suction fluid from the leakage side so as to extremely reduce leakage. In addition, since the dimple angle of the dimples arranged on the sealed fluid side is small, the dynamic pressure effect becomes predominant, and thus the dimples may discharge high-pressure fluid so as to reduce sliding torque.

The dimple angle is characterized by changing at a constant rate in the circumferential direction.

According to this feature, by changing the dimple angle of the dimples constituting the dimple group at the constant rate in the circumferential direction, a fluid holding effect, the suction effect, and a sealing effect of the dimples may be changed in the circumferential direction.

The sliding component according to the present invention is characterized in that
the dimple angle discontinuously changes in the circumferential direction.

According to this feature, by discontinuously changing the dimple angle in the circumferential direction, the suction effect and the dynamic pressure effect of the dimples constituting the dimple group may be discontinuously changed in the circumferential direction, and thus a dimple group suitable for operating conditions in a specific range may be arranged.

The sliding component according to the present invention is characterized in that
a rate of change in the dimple angle in the circumferential direction changes in the circumferential direction.

According to this feature, by changing, in the circumferential direction, the rate of change in the dimple angle in the circumferential direction, dimples suitable for respective use conditions may be easily arranged in the radial direction.

The sliding component according to the present invention is characterized in that.

According to this feature, dimples suitable for various operating conditions may be arranged in each region, and thus favorable sealing performance and low sliding torque may be achieved.

The sliding component according to the present invention is characterized in that
the shape of the opening portion of the dimple is an ellipse.

According to this feature, by utilizing a difference in the suction effect and the dynamic pressure effect between a long axis direction and a short axis direction of each elliptical dimple, dimples suitable for various operating conditions may be arranged, and thus favorable sealing performance and low sliding torque may be achieved.

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.

A sliding component according to Embodiment <NUM> of the present invention will be described with reference to <FIG> and <FIG>. 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> is a vertical cross-sectional view showing an example of a mechanical seal <NUM>, 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 <NUM> fitted to a rotation shaft <NUM>, an annular rotation-side sealing ring <NUM> that is one sliding component, and a packing <NUM> that seals space between the sleeve <NUM> and the rotation-side sealing ring <NUM>. The rotation-side cartridge rotates together with the rotation shaft <NUM>.

The fixed-side cartridge includes a housing <NUM> attached to a casing <NUM>, an annular fixed-side sealing ring <NUM> that is another sliding component, a bellows <NUM> that seals space between the fixed-side sealing ring <NUM> and the housing <NUM>, and a coiled wave spring <NUM> that urges the fixed-side sealing ring <NUM> toward the rotation-side sealing ring <NUM> via the bellows <NUM>. The housing <NUM> is fixed to the casing <NUM> in a rotation direction and an axial direction.

In the mechanical seal <NUM> having the above configuration, the sliding surface S of the rotation-side sealing ring <NUM> and the sliding surface S of the fixed-side sealing ring <NUM> 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> shows a case where a width of the sliding surface of the rotation-side sealing ring <NUM> is wider than a width of the sliding surface of the fixed-side sealing ring <NUM>, 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 <NUM> and the fixed-side sealing ring <NUM> 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 <NUM> and the fixed-side sealing ring <NUM> may be made of SiC, or the rotation-side sealing ring <NUM> may be made of SiC while the fixed-side sealing ring <NUM> is made of carbon.

As shown in <FIG>, the fixed-side sealing ring <NUM> includes a plurality of dimples <NUM>. In the present invention, each dimple <NUM> is a recess that includes an opening portion 11a surrounded by the flat sliding surface S and a bottom portion that is recessed relative to the sliding surface S. The opening portion 11a of the dimple <NUM> has a shape having a long axis L and a short axis K orthogonal to each other. In addition, the dimples <NUM> are spaced apart from each other with land portions interposed therebetween. In the present invention, the long axis L is an imaginary line that passes through a centroid of the shape of the opening portion 11a and connects maximum width portions of the opening portion 11a while the short axis K is an imaginary line that passes through the centroid of the opening portion 11a and connects opposite portions of the opening portion 11a in a direction orthogonal to the long axis L. In the present embodiment, an example in which the opening portion 11a of the dimple <NUM> is an ellipse having the long axis L and the short axis K orthogonal to each other will be described. However, the shape is not limited to an ellipse, and may be an oval shape, a rhombus shape, a triangular shape, a rectangular shape, a polygonal shape, or any shape formed by closed curves <NUM>, <NUM>, <NUM>, or <NUM> as shown in <FIG>, as long as the shape has the long axis and the short axis orthogonal to each other.

Next, a function of each dimple <NUM> will be explained. When the fixed-side sealing ring <NUM> provided with the dimples <NUM> and the rotation-side sealing ring <NUM> facing the fixed-side sealing ring <NUM> are moved relative to each other, fluid between the sliding surfaces S and fluid in the dimples <NUM> are moved following a moving direction of the rotation-side sealing ring <NUM> due to viscosity of the fluid. Since a flow path of the fluid flowing into the dimple <NUM> rapidly expands, negative pressure is generated on an upstream side of the dimple <NUM>, 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 <NUM>, the fluid is pressurized to positive pressure by a wedge effect (dynamic pressure effect) due to rapid contraction of a flow path. Due to the negative pressure generated on the upstream side of the dimple <NUM>, the dimple <NUM> exhibits a suction effect of suctioning surrounding fluid. On the other hand, on the downstream side of the dimple <NUM>, the fluid pressurized by the wedge effect is supplied to the sliding surfaces S, and thus a fluid lubricating state is maintained between the sliding surfaces S.

A dimple angle will be explained. As shown in <FIG>, a dimple angle θ is the angle between a radial axis r, which passes through a center C of the sliding surface S and an intersection (the centroid ) of the long axis L and the short axis K of the dimple <NUM>, and the long axis L.

In addition, a suction effect and a dynamic pressure effect of the dimple <NUM> are different depending on a magnitude of the dimple angle θ. When the dimple angle θ is <NUM>°, that is, when the long axis L of the dimple <NUM> is arranged along a circumferential direction, a fluid holding function of the dimple <NUM> is improved. When the dimple angle θ is about <NUM>°, the suction effect of the dimple <NUM> is improved. In addition, when the dimple angle is <NUM>°, that is, when the long axis L of the dimple <NUM> is arranged along a radial direction, the dynamic pressure effect is improved. In this way, even when each dimple <NUM> has the same elliptical shape and the same depth, the suction effect and the dynamic pressure effect may be improved by arranging the dimples <NUM> while changing the dimple angle. Further, by changing the elliptical shape and the depth, dimples may have more diverse characteristics.

Next, a dimple group <NUM> will be explained. As shown in <FIG>, the dimple group <NUM> is formed by arranging, at equal intervals in the circumferential direction, a predetermined number (<NUM> in the example of <FIG>) of sub dimple groups <NUM> and <NUM> that are arranged in a row in the radial direction. The sub dimple groups <NUM> are arranged in a row in the radial direction on one peripheral edge (on the leakage side) of the sliding surface S, while the sub dimple groups <NUM> are arranged in a row in the radial direction on the other peripheral edge (on the sealed fluid side) of the sliding surface. Dimples 62a, 62b, 62c, 62d, and 62e constituting each sub dimple group <NUM> arranged on the leakage side are arranged at the dimple angle θ of <NUM>° each. In addition, dimples 63a, 63b, 63c, 63d, and 63e constituting each sub dimple group <NUM> arranged on the sealed fluid side are arranged at the dimple angle θ of <NUM>° each. That is, the dimple angle θ of the sub dimple group <NUM> and the dimple angle θ of the sub dimple group <NUM> are set to discontinuously change in the radial direction.

Here, the dimples 62a, 62b, 62c, 62d, and 62e, and the dimples 63a, 63b, 63c, 63d, and 63e are formed to be ellipses whose opening portions have the same shape and depth. Although each of the sub dimple groups <NUM> and the sub dimple groups <NUM> is constituted by five dimples in the embodiment in <FIG>, the present invention is not limited thereto. The number of dimples constituting each of the sub dimple groups <NUM> and the sub dimple groups <NUM> may be <NUM> or more, <NUM> or less, or may be different from each other. In addition, although the number of sub dimple groups <NUM> and the number of sub dimple groups <NUM> are <NUM> each on the sliding surface, the number may also be more than <NUM> or less than <NUM>. Further, although the sub dimple groups <NUM> and <NUM> aligned in the radial direction are arranged at equal intervals in the circumferential direction, the sub dimple groups <NUM> and <NUM> may also be arranged at unequal intervals in the circumferential direction.

Since the dimples 62a, 62b, 62c, and 62d constituting each sub dimple group <NUM> are arranged at the dimple angle θ of <NUM>°, the suction effect is predominant over the dynamic pressure effect in the dimples 62a, 62b, 62c and 62d, and thus the sub dimple group <NUM> as a whole exhibits a favorable suction effect. In addition, since the dimples 63a, 63b, 63c, and 63d constituting each sub dimple group <NUM> are arranged at the dimple angle θ of <NUM>°, the dynamic pressure effect is predominant over the suction effect in the dimples 63a, 63b, 63c, and 63d, and thus the sub dimple group <NUM> as a whole exhibits a favorable dynamic pressure effect.

Therefore, by arranging the sub dimple group <NUM> having the favorable suction effect on the leakage side of the sliding surface, the sub dimple group <NUM> suctions fluid from the leakage side, and thus leakage may be extremely reduced. In addition, by arranging the sub dimple group <NUM> having the favorable dynamic pressure effect on the sealed fluid side of the sliding surface, the sub dimple group <NUM> supplies high pressure fluid to the sliding surface S, and thus sliding torque may be extremely reduced.

As described above, the sliding component of Embodiment <NUM> has the following effects.

A sliding component according to Embodiment <NUM> will be described. <FIG> shows the sliding surface S of the sliding component according to Embodiment <NUM>. In a dimple group <NUM> of Embodiment <NUM>, the dimple angle θ changes at a constant rate in the radial direction, which is different from Embodiment <NUM>. Hereinafter, the same members and configurations as those of Embodiment <NUM> will be denoted by the same reference numerals, and redundant description thereof will be omitted.

As shown in <FIG>, the dimple group <NUM> is formed by arranging, at equal intervals in the circumferential direction, a predetermined number (<NUM> in the example of <FIG>) of sub dimple groups <NUM> that are arranged in a row in the radial direction. The sub dimple group <NUM> is formed by arranging dimples 72a, 72b, 72c, 72d, 72e, 72f, <NUM>, <NUM>, 72i, and 72j with land portions interposed therebetween in the radial direction. (Hereinafter, the dimples 72a, 72b, 72c, 72d, 72e, 72f, <NUM>, <NUM>, 72i, and 72j will be referred to as the "dimples 72a to 72j ").

In the sub dimple group <NUM>, the dimple 72a arranged on the leakage side of the sliding surface S is arranged at the dimple angle of <NUM>°, and the dimple 72j arranged on the sealed fluid side of the sliding surface S is arranged at the dimple angle of <NUM>°. Therefore, the dimple angle θ of the dimples 72a to 72j constituting the sub dimple group <NUM> changes from <NUM>° to <NUM>° at a constant rate in the radial direction from the dimple 72a toward the dimple 72j.

Even though the dimples 72a to 72j constituting the sub dimple group <NUM> are ellipses having the same shape, the dimple angles θ thereof are different from each other, and thus the suction effect and the dynamic pressure effect may be continuously changed. Among the dimples 72a to 72j constituting the sub dimple group <NUM>, the dimple 72a arranged closer to a leakage-side peripheral edge 5a of the sliding surface has the dimple angle of <NUM>°, and thus the suction effect is maximum. In addition, since the dimple angle decreases toward the sealed fluid side, the suction effect is gradually weakened, and the dynamic pressure effect of the dimple 72j arranged closer to a peripheral edge 5b on the sealed fluid side of the sliding surface is maximum.

Since the dimple angle of the dimples 72a to 72j constituting the dimple group <NUM> continuously changes at the constant rate in the radial direction, the suction effect and the dynamic pressure effect may be continuously changed. As a result, even when use conditions such as rotation speed and pressure are changed, there are dimples 72a to 72j suitable for the respective use conditions. As a result, the mechanical seal <NUM> may reduce leakage and may reduce sliding torque even when the use conditions are changed.

As described above, the sliding component of Embodiment <NUM> has the following effects in addition to the effects of Embodiment <NUM>.

Since the dimple angle θ of the dimples 72a to 72j constituting the dimple group <NUM> continuously changes at the constant rate in the radial direction, the suction effect and the dynamic pressure effect may be continuously changed. As a result, even when use conditions such as rotation speed and pressure are changed, there are dimples 72a to 72j suitable for the respective use conditions. As a result, the mechanical seal <NUM> may reduce leakage and may reduce sliding torque even when the use conditions are changed.

A sliding component according to Embodiment <NUM> of the present invention will be described. <FIG> shows the sliding surface S of the sliding component according to Embodiment <NUM>, in which a dimple 12a having the dimple angle θ of <NUM>° is arranged on the leakage side of the sliding surface S while a dimple 12j having the dimple angle θ of <NUM>° is arranged on the sealed fluid side in a dimple group <NUM>, which is different from Embodiment <NUM>. Other configurations are the same as those of Embodiment <NUM>. Hereinafter, the same members and configurations as those of Embodiment <NUM> will be denoted by the same reference numerals, and redundant description thereof will be omitted.

As shown in <FIG>, the dimple group <NUM> is formed by arranging, at equal intervals in the circumferential direction, a predetermined number (<NUM> in the example of <FIG>) of sub dimple groups <NUM> that are arranged in a row in the radial direction. The sub dimple group <NUM> is formed by arranging dimples 12a, 12b, 12c, 12d, 12e, 12f, <NUM>, <NUM>, 12i, and 12j with the land portions interposed therebetween in the radial direction (hereinafter, the dimples 12a, 12b, 12c, 12d, 12e, 12f, <NUM>, <NUM>, 12i, and 12j are referred to as the "dimples 12a to 12j "). The dimple angle θ of the dimples 12a to 12j constituting the sub dimple group <NUM> changes from <NUM>° to <NUM>° at a constant rate in the radial direction from the dimple 12a on the leakage side toward the dimple 12j on the sealed fluid side. Here, shapes and sizes of ellipses of opening portions of the dimples 12a to 12j are substantially the same. The number of dimples constituting each sub dimple group <NUM> may also be more than or less than <NUM>. In addition, the number of the sub dimple groups <NUM> arranged on the sliding surface S may also be more than <NUM> or less than <NUM>.

Even though the dimples 12a to 12j constituting the sub dimple group <NUM> are ellipses having the same shape, the dimple angle θ of the dimples 12a to 12j constituting the sub dimple group <NUM> changes at the constant rate in the radial direction, and thus the suction effect and the dynamic pressure effect may be continuously changed. Specifically, when each dimple is arranged at the dimple angle θ of <NUM>, the dimple has a favorable fluid holding function. When the dimple angle θ is about <NUM>°, the suction effect of the dimple is improved. In addition, at the dimple angle of <NUM>°, the dynamic pressure effect of the dimple is improved.

As a result, the dimples 12a, 12b, and 12c arranged on the leakage side where circumferential speed is low have the large dimple angle θ, and thus have a favorable fluid holding function. In particular, when operating at low rotation speed or when an inner diameter side of the sliding surface S where circumferential speed is low is likely to be in a poor lubrication state, the dimples 12a, 12b, and 12c having the dimple angle θ of <NUM>° to <NUM>° are arranged on the inner diameter side of the sliding surface S, and thus fluid held in the dimples 12a, 12b, and 12c may be supplied to the sliding surface S so as to prevent the poor lubrication state.

Since the dimples 12d, 12e, and 12f having the dimple angle θ of <NUM>° are arranged in a central portion of the sliding surface S, the suction effect is improved. As a result, since fluid is suctioned into the dimples 12d, 12e, and 12f from the sealed fluid side, flow to the leakage side is prevented, and thus sealing performance may be improved.

In addition, since the dimples <NUM>, <NUM>, 12i, and 12j each having the small dimple angle θ are arranged on the sealed fluid side where circumferential speed is high, the dynamic pressure effect may be improved. As a result, the dimples <NUM>, <NUM>, 12i, and 12j arranged on the sealed fluid side where circumferential speed is high supply high-pressure fluid to the sliding surface S due to the dynamic pressure effect, and thus a fluid lubricating state may be maintained between the sliding surfaces S.

A sliding component according to Embodiment <NUM> of the present invention will be described. <FIG> shows the sliding surface S of the sliding component according to Embodiment <NUM> in which the dimple angle θ of dimples constituting each dimple group <NUM> is arranged to be constant in the radial direction and to continuously change in the circumferential direction, which is different from Embodiment <NUM>. Other configurations are the same as those of Embodiment <NUM>. Hereinafter, the same members and configurations as those of Embodiment <NUM> will be denoted by the same reference numerals, and redundant description thereof will be omitted.

As shown in <FIG>, the sliding surface S of the fixed-side sealing ring <NUM> is partitioned into a predetermined number (four in the example of <FIG>) of regions <NUM> by the land portions provided from the sealed fluid side to the leakage side. The dimple groups <NUM> are arranged in the respective regions. In each dimple group <NUM>, <NUM> sub dimple groups from a sub dimple group <NUM> to a sub dimple group <NUM> are arranged at equal intervals in the circumferential direction with the land portions interposed therebetween. In each of the sub dimple groups <NUM> to <NUM>, <NUM> dimples are arranged at equal intervals in a row in the radial direction. Although <NUM> dimples are arranged in each of the sub dimple groups <NUM> to <NUM> in the embodiment in <FIG>, the number is not limited thereto, and may also be more than <NUM> or less than <NUM>. In addition, the number of sub dimple groups arranged in each region is not limited to <NUM>, and may also be more than <NUM> or less than <NUM>.

As shown in <FIG>, the sub dimple group <NUM> is arranged at one end portion (on a rotation direction upstream side) of the region <NUM>, while the sub dimple group <NUM> is arranged at the other end portion (on a rotation direction downstream side) of the region <NUM>. The sub dimple group <NUM> is formed by arranging dimples 21a, 21b, 21c, 21d, 21e, 21f, <NUM>, <NUM>, and 21i (hereinafter referred to as the "dimples 21a to 21i") in a row from one peripheral edge (on the leakage side) to the other peripheral edge (on the sealed fluid side) of the sliding surface S with the land portions interposed therebetween. The dimple angle of the dimples 21a to 21i constituting the sub dimple group <NUM> is constant in the radial direction, that is, each of the dimples 21a to 21i has the dimple angle of <NUM>°. In addition, the sub dimple group <NUM> is formed by arranging dimples 50a, 50b, 50c, 50d, 50e, 50f, <NUM>, <NUM>, and 50i (hereinafter referred to as the "dimples 50a to 50i") in a row from the leakage side to the sealed fluid side of the sliding surface S with the land portions interposed therebetween. The dimple angle of the dimples 50a to 50i is constant in the radial direction, that is, the dimple angle of the dimples 50a to 50i is arranged at the dimple angle of <NUM>°. From the sub dimple group <NUM> toward the sub dimple group <NUM>, the dimple angle of the dimples constituting the sub dimple groups <NUM> to <NUM> is arranged to change at a constant rate in the circumferential direction from the dimple angle θ of <NUM>° to <NUM>°.

Since the sub dimple group <NUM> having the dimple angle of <NUM>° is arranged on the rotation direction upstream side of the region <NUM>, a holding effect of holding fluid in the dimples is predominant over the suction effect and the dynamic pressure effect. In addition, since the sub dimple group <NUM> having the dimple angle of <NUM>° is arranged on the rotation direction downstream side of the region <NUM>, the dynamic pressure effect is predominant over the suction effect. Further, since the dimple group having the dimple angle of <NUM>° is arranged in a middle flow region between the upstream side and the downstream side of the region <NUM>, the suction effect is predominant. That is, since the dimple angle of the sub dimple groups <NUM> to <NUM> is arranged to change in the circumferential direction from the sub dimple group <NUM> toward the sub dimple group <NUM> from the dimple angle θ of <NUM>° to <NUM>°, dimple groups having different characteristics are evenly distributed from the sub dimple group <NUM> to the sub dimple group <NUM>, thus dimple groups suitable for various operating conditions are arranged, and thus favorable sealing performance and low sliding torque may be achieved under the various operating conditions.

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.

<FIG> show modifications of a manner in which the dimple angle θ changes in the radial direction of the sliding surface S. The dimple angle θ may be changed in the radial direction so as to meet required operating conditions.

<FIG> corresponds to the embodiment of <FIG>, and shows a case where the dimple angle discontinuously changes in the radial direction of the sliding surface S. The dimple angle θ of the dimples constituting the sub dimple group arranged on the leakage side of the sliding surface S and the dimple angle θ of the dimples constituting the sub dimple group arranged on the sealed fluid side of the sliding surface S are set to be different.

<FIG> is a modification of <FIG>, and shows a case where a rate of change in the dimple angle on the leakage side of the sliding surface is different from a rate of change in the dimple angle on the sealed fluid side of the sliding surface. The dimples constituting the dimple group arranged on the leakage side of the sliding surface S all have the constant dimple angle θ, and the dimple angle does not change, while the dimple angle θ of the dimples constituting the dimple group arranged on the sealed fluid side of the sliding surface S changes at a constant rate in the radial direction.

<FIG> corresponds to the embodiments of <FIG> and <FIG>, and the dimple angle θ of the dimples constituting the dimple group is set to change at a constant rate in the radial direction.

<FIG> shows a case where the rate of change in the dimple angle on the leakage side of the sliding surface is different from the rate of change in the dimple angle on the sealed fluid side of the sliding surface. The dimple angle θ of the dimples constituting the dimple group arranged on the leakage side of the sliding surface S changes at a constant rate in the radial direction. On the other hand, the dimple angle θ of all the dimples constituting the sub dimple group arranged on the sealed fluid side of the sliding surface S has the constant dimple angle θ, and the dimple angle does not change.

<FIG> show modifications of a manner in which the dimple angle θ changes in the circumferential direction of the sliding surface S. The dimple angle θ may be changed in the circumferential direction so as to meet required operating conditions.

<FIG> shows a case where the dimple angle discontinuously changes from one side to the other side in a region provided along the circumferential direction of the sliding surface.

<FIG> shows a case where the rate of change in the dimple angle on the one side of the region is different from the rate of change in the dimple angle on the other side of the region.

<FIG> corresponds to the embodiment of <FIG>, and shows a case where the dimple angle changes at a constant rate in the circumferential direction.

In Embodiments <NUM> to <NUM>, the dimple angle of the dimples constituting the dimple group changes in the radial direction and is constant in the circumferential direction. In addition, in Embodiment <NUM>, the dimple angle of the dimples constituting the dimple group changes in the circumferential direction and is constant in the radial direction. However, the present invention is not limited thereto, and the dimple angle of the dimples constituting the dimple group may also be set to change in the radial direction and the circumferential direction so as to meet required operating conditions.

Although the dimples <NUM> constituting the dimple group have the same shape, size, and depth in the above embodiment, at least one of shapes, sizes, and depths of adjacent dimples may be different from each other. In addition, the shapes, sizes, and depths of the dimples may be different for each sub dimple group. By arranging dimples having different dimple angles as well as different dimple sizes, shapes, sizes, and depths in the sliding surface S, it is possible to arrange dimples suitable for a wide range of operating conditions in the sliding surface S, and thus it is possible to provide a sliding component having favorable sealing performance and small sliding torque corresponding to a wide range of operating conditions.

Claim 1:
A sliding component comprising a pair of sliding members (<NUM>, <NUM>) being slidable relative to each other on sliding surfaces (S) of the sliding members,
wherein at least one of the sliding surfaces (S) includes a dimple group (<NUM>, <NUM>, <NUM>) in which dimples (<NUM>, 12a) are arranged in a radial direction and a circumferential direction, each of the dimples having an opening portion (11a) a shape of which has a long axis (L) and a short axis (K) orthogonal to the long axis (L), and
a dimple angle (θ) formed by a radial axis (r) passing through an intersection of the long axis and the short axis of the dimple and a rotational center of the one of the sliding surfaces (S) and the long axis changes in the radial direction of the one of the sliding surfaces (S), and
characterized in that the dimple angle (θ) changes such that it is larger on a leakage side of the one of the sliding surfaces (S) and smaller on a sealed fluid side of the one of the sliding surfaces (S).