Patent Description:
As a seal device that prevents leakage of a sealed liquid, for example, there is a mechanical seal including a pair of sliding components which have an annular shape and rotate relative to each other to cause sliding surfaces to slide against each other. In such a mechanical seal, in recent years, there has been a desire that energy lost by sliding is reduced for environmental measures, and the sliding surface of the sliding component is provided with a positive pressure generating groove communicating with an outer diameter side which is a sealed liquid side of a high pressure, and having a closed one end in the sliding surface. Accordingly, when the sliding components rotate relative to each other, a positive pressure is generated in the positive pressure generating
groove to separate the sliding surfaces from each other, and the sealed liquid is introduced into the positive pressure generating groove from the outer diameter side to be held therein. Therefore, the lubricity is improved, and the friction is reduced.

Further, in order to maintain sealability for a long period of time, the mechanical seal is required to satisfy a condition such as "sealing" in addition to "lubrication". For example, in a mechanical seal described in Patent Citation <NUM>, one sliding component is provided with a Rayleigh step and a reverse Rayleigh step that communicate with a sealed liquid side. Accordingly, when sliding components rotate relative to each other, a positive pressure is generated between sliding surfaces by the Rayleigh step, to separate the sliding surfaces from each other, and the Rayleigh step holds a sealed liquid. Therefore, the lubricity is improved. Meanwhile, since a relatively negative pressure is generated in the reverse Rayleigh step, and the reverse Rayleigh step is disposed closer to a leakage side than the Rayleigh step, the sealed liquid of a high pressure which has flowed out from the Rayleigh step to a gap between the sliding surfaces can be suctioned into the reverse Rayleigh step. In such a manner, the sealed liquid between a pair of the sliding components is prevented from leaking to the leakage side, so that the sealability is improved.

Further mechanical seals and respective sliding components are disclosed in Patent Citations <NUM> to <NUM>.

In Patent Citation <NUM> a plane sliding mechanism is disclosed which seals the inside diameter side and the outside diameter side by performing relative rotational sliding between flat surfaces, facing each other, through a film of lubrication fluid. On any one of flat surfaces, there are provided a fluid guiding groove which is opened on either the inside diameter side or outside diameter side, with an end part in the opposite radial direction of the opening part being present in the flat surface, for guiding a lubrication fluid from the opening side to a ring-like sliding part between the flat surfaces, facing each other, and a plurality of shallow grooves that are shallower than the fluid guiding groove while communicating with the fluid guiding groove, having periodicity along the direction parallel to the sliding direction of the other flat surfaces, facing each other, otherwise inclined by an inclination angle of below <NUM>°.

Patent Citation <NUM> and Patent Citation <NUM> describe sliding parts suitable for a mechanical seal, a bearing, and other sliding portions for example. In particular, Patent Citation <NUM> relates to sliding parts such as a sealing ring or a bearing in which a fluid lies on sealing faces to reduce friction and there is a need for preventing fluid leakage from the sealing faces.

Further, in Patent Citation <NUM> a sliding component is described that is capable of simultaneously satisfying opposing conditions of sealing and lubrication when a gas is on the high-pressure fluid side and a liquid is on the low-pressure fluid side.

However, in Patent Citation <NUM>, since a structure where the reverse Rayleigh step causes the sealed liquid to return to the sealed liquid side is adopted, the sealed liquid is not supplied to the leakage side in the gap between the sliding surfaces, and there is a portion which has no contribution to lubricity, which is a problem. Therefore, sliding components having higher lubricity are required.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a sliding component that supplies a sealed fluid to a leakage
side in a gap between sliding surfaces to exhibit high lubricity and has a small leakage of the sealed fluid.

In order to solve the above problem, according to the present invention, there is provided a sliding component that has an annular shape and is disposed in a place where relative rotation is performed in a rotary machine, including a plurality of dynamic pressure generating mechanisms, in which the plurality of dynamic pressure generating mechanisms are provided in a sliding surface of the sliding component, each of the dynamic pressure generating mechanisms including a deep groove portion that communicates with a leakage side, and at least one shallow groove portion that communicates with the deep groove portion and extends in a circumferential direction. The shallow groove portion being shallower than the deep groove portion. The sliding surface of the sliding component is provided with a specific dynamic pressure generating mechanism that is disposed on a sealed fluid side with respect to the dynamic pressure generating mechanism and is independent of the dynamic pressure generating mechanism, and a volume of the dynamic pressure generating mechanism is larger than a volume of the specific dynamic pressure generating mechanism. According to the aforesaid feature of the present invention, the deep groove portion has a deep groove depth and a large volume, so that a large amount of the sealed fluid supplied to the leakage side of the sliding
surface is recovered, and the sealed fluid flows out from the shallow groove portion to a gap between sliding surfaces. Therefore, lubricity can be improved over a wide area of the sliding surface. In addition, since the sealed fluid is recovered by the deep groove portion communicating with the leakage side, and the recovered sealed fluid flows out from the shallow groove portion to the gap between the sliding surfaces to partly return to a sealed fluid side in a radial direction, the amount of the sealed fluid leaking to the leakage side is small.

It might be preferable that the deep groove portion extends in a radial direction. According to this preferable configuration, the sealed fluid can be held in the deep groove portion without being affected by dynamic pressure.

It might be preferable that a step in a depth direction is formed in a communication part between the shallow groove portion and the deep groove portion. According to this preferable configuration, the sealed fluid can be held in the deep groove portion without being affected by dynamic pressure.

It might be preferable that each of the plurality of dynamic pressure generating mechanisms includes a first shallow groove portion and a second shallow groove portion extend from each of the deep groove portions to both sides in the circumferential direction. According to this preferable configuration, the shallow groove portion which is disposed on one side in the circumferential direction of the deep groove portion can be used as a shallow groove portion for generating dynamic pressure. Therefore, the shallow groove portions can be used without being limited by the relative rotational direction of the sliding component.

It might be preferable that the plurality of dynamic pressure generating mechanisms includes a first dynamic pressure generating mechanism and a second dynamic pressure generating mechanism adjacent to each other in the circumferential direction, the first shallow groove portion of the first dynamic pressure generating mechanism is adjacent, in the circumferential direction, to the second shallow groove portion of the second dynamic pressure generating mechanism.

According to this preferable configuration, during relative rotation of the sliding component, the sealed fluid which is supplied from the one shallow groove portion of the dynamic pressure generating mechanism to the gap between the sliding surfaces to tend to move the leakage side can be recovered by the other shallow groove portion of the dynamic pressure generating mechanism adjacent thereto.

It might be preferable that the deep groove portion communicates with an inner diameter side of the sliding component. According to this preferable configuration, the sealed fluid which has been supplied from the shallow groove portion to the gap between the sliding surfaces can return to the sealed fluid side due to centrifugal force, and the sealed fluid is easily held in the deep groove portion due to centrifugal force.

According to the present invention the sliding surface of the sliding component may be provided with a specific dynamic pressure generating mechanism that is disposed on a sealed fluid side with respect to the dynamic pressure generating mechanism and is independent of the dynamic pressure generating mechanism. According to this preferable configuration, during relative rotation of the sliding component, while the specific dynamic pressure generating mechanism separates the sliding surfaces from each other to form an appropriate fluid film between the sliding surfaces, the amount of leakage of the sealed fluid to the leakage side can be reduced. It might be preferable that the specific dynamic pressure generating mechanism includes a deep groove portion that communicates with the sealed fluid side, and shallow groove portions that communicate with the deep groove portion of the specific dynamic pressure generating mechanism and extends in a circumferential direction, the shallow groove portion being shallower than the deep groove portion.

Incidentally, the fact that the shallow groove portion of the sliding component according to the present invention extends in the circumferential direction means that the shallow groove portion may extend with at least a component in the circumferential direction, preferably, may extend such that the component along the circumferential direction is larger than the component in the radial direction. In addition, the fact that the deep groove portion extends in the radial direction means that the deep groove portion may extend with at least a component in the radial direction, preferably, may extend such that the component along the radial direction is larger than the component in the circumferential direction.

In addition, the sealed fluid may be a liquid, or have a mist form in which a liquid and a gas are mixed.

Modes for implementing a sliding component according to the present invention will be described below based on embodiments.

A sliding component according to a first embodiment of the present invention will be described with reference to <FIG>. Incidentally, in the present embodiment, a mode in which the sliding component is a mechanical seal will be described as an example. In addition, a description will be given based on the premise that an outer diameter side of the sliding component forming the mechanical seal is a sealed liquid side (i.e., high-pressure side) as a sealed fluid side and an inner diameter side is an atmosphere side (i.e., low-pressure side) as a leakage side. In addition, for convenience of description, in the drawings, dots may be added to a groove and the like formed in a sliding surface.

A mechanical seal for a general industrial machine illustrated in <FIG> is an inside mechanical seal that seals a sealed liquid F which tends to leak from an outer diameter side of sliding surfaces toward an inner diameter side, and mainly includes a rotating seal ring <NUM> which is a sliding component that has an annular shape and is provided on a rotating shaft <NUM> with a sleeve <NUM> interposed therebetween, to be rotatable together with the rotating shaft <NUM>, and a stationary seal ring <NUM> that has an annular shape and is a sliding component which is provided on a seal cover <NUM> fixed to a housing <NUM> of a mounted apparatus, to not be rotated but be movable in an axial direction. The stationary seal ring <NUM> is biased in the axial direction by a bellows <NUM>, so that a sliding surface <NUM> of the stationary seal ring <NUM> and a sliding surface <NUM> of the rotating seal ring <NUM> slide against each other in close contact with each other. Incidentally, the sliding surface <NUM> of the rotating seal ring <NUM> is a flat surface, and a recessed portion is not provided in the flat surface.

The stationary seal ring <NUM> and the rotating seal ring <NUM> are representatively made of SiC (as an example of hard material) or a combination of SiC (as the example of hard material) and carbon (as an example of soft material); the sliding material is not limited thereto, and any type of sliding material is applicable as long as the sliding material is used as a sliding material for a mechanical seal. Incidentally, as the SiC, there are materials consisting of different components and compositions of two or more phases including a sintered body in which boron, aluminum, carbon, or the like is used as a sintering additive, for example, reaction-sintered SiC, SiC-TiC, SiC-TiN, and the like consisting of Sic or SiC and Si in which graphite particles are dispersed. As the carbon, resin molded carbon, sintered carbon, and the like carbon including carbon in which a carbonaceous material and a graphite material are mixed can be used. In addition, in addition to the above sliding materials, metallic materials, resin materials, surface modifiers (such as coating materials), composite materials, or the like are also applicable.

As illustrated in <FIG>, the rotating seal ring <NUM> slides relative to the stationary seal ring <NUM> as indicated by an arrow, and a plurality of dynamic pressure generating mechanisms <NUM> are evenly provided in the sliding surface <NUM> of the stationary seal ring <NUM> in a circumferential direction of the stationary seal ring <NUM>. A portion of the sliding surface <NUM> other than the dynamic pressure generating mechanisms <NUM> is a land <NUM> forming a flat surface.

Next, an outline of the dynamic pressure generating mechanism <NUM> will be described based on <FIG>. Incidentally, hereinafter, a description will be given based on the premise that when the stationary seal ring <NUM> and the rotating seal ring <NUM> rotate relative to each other, the left side of the drawing sheet of <FIG> is a downstream side of the sealed liquid F flowing in a Rayleigh step 9A to be described later, and the right side of the drawing sheet of <FIG> is an upstream side of the sealed liquid F flowing in the Rayleigh step 9A.

The dynamic pressure generating mechanism <NUM> includes a liquid guide groove portion <NUM> as a deep groove portion that communicates with the atmosphere side and extends in an outer diameter direction, and the Rayleigh step 9A as a shallow groove portion that extends concentrically with the stationary seal ring <NUM> from an outer diameter side end portion of the liquid guide groove portion <NUM> toward the downstream side in the circumferential direction. Namely, the dynamic pressure generating mechanism <NUM> has an inverted L shape formed by the liquid guide groove portion <NUM> and the Rayleigh step 9A, when seen in a direction orthogonal to the sliding surface <NUM>. Incidentally, the liquid guide groove portion <NUM> of the first embodiment extends in a radial direction to be orthogonal to an axis of the stationary seal ring <NUM>. In addition, the liquid guide groove portion <NUM> and the Rayleigh step 9A communicate with each other, and a step <NUM> in a depth direction is formed in a communication part.

In addition, a wall portion 9a orthogonal to a rotational direction is formed in an end portion on the downstream side of the Rayleigh step 9A. Incidentally, the wall portion 9a is not limited to being orthogonal to the rotational direction, for example, may be inclined with respect to the rotational direction or may be formed in a step shape.

In addition, a depth dimension L10 of the liquid guide groove portion <NUM> is larger than a depth dimension L20 of the Rayleigh step 9A (L10 > L20). Specifically, in the first embodiment, the depth dimension L10 of the liquid guide groove portion <NUM> is <NUM>, and the depth dimension L20 of the Rayleigh step 9A is <NUM>. Namely, the step <NUM> in the depth direction is formed between the liquid guide groove portion <NUM> and the Rayleigh step 9A by a side surface on the downstream side of the liquid guide groove portion <NUM> and a bottom surface of the Rayleigh step 9A. Incidentally, as long as the depth dimension of the liquid guide groove portion <NUM> is larger than the depth dimension of the Rayleigh step 9A, the depth dimensions of the liquid guide groove portion <NUM> and the Rayleigh step 9A can be freely changed, and it is preferable that the dimension L10 is five times or more the dimension L20.

Incidentally, the bottom surface of the Rayleigh step 9A is a flat surface and is formed in parallel to the land <NUM>; however, the flat surface is not prevented from being provided with a fine recessed portion or being formed to be inclined with respect to the land <NUM>. Further, each of two arc-shaped surfaces of the Rayleigh step 9A is orthogonal to the bottom surface of the Rayleigh step 9A, the two arc-shaped surfaces extending in the circumferential direction. In addition, a bottom surface of the liquid guide groove portion <NUM> is a flat surface and is formed in parallel to the land <NUM>; however, the flat surface is not prevented from being provided with a fine recessed portion or being formed to be inclined with respect to the land <NUM>. Further, each of two flat surfaces of the liquid guide groove portion <NUM> is orthogonal to the bottom surface of the liquid guide groove portion <NUM>, the two flat surfaces extending in the radial direction.

Next, the operation during relative rotation of the stationary seal ring <NUM> and the rotating seal ring <NUM> will be described. First, during non-operation of the general industrial machine, namely, when the rotating seal ring <NUM> does not rotate, a slight amount of the sealed liquid F on the outer diameter side of the sliding surfaces <NUM> and <NUM> enters a gap between the sliding surfaces <NUM> and <NUM> due to the capillary phenomenon, and in the dynamic pressure generating mechanism <NUM>, the sealed liquid F which has remained during stop of the general industrial machine and the atmosphere which has entered from the inner diameter side of the sliding surfaces <NUM> and <NUM> are mixed. Incidentally, since the sealed liquid F has a higher viscosity than a gas, the amount of leakage from the dynamic pressure generating mechanism <NUM> to a low-pressure side during stop of the general industrial machine is small.

In a case where almost no sealed liquid F remains in the dynamic pressure generating mechanism <NUM> during stop of the general industrial machine, when the rotating seal ring <NUM> rotates relative to the stationary seal ring <NUM> (refer to the black arrow of <FIG>), as illustrated in <FIG>, a low-pressure side fluid A on the atmosphere side is introduced from the liquid guide groove portion <NUM> as indicated by an arrow L1, and the Rayleigh step 9A causes the low-pressure side fluid A to move in a following manner in the rotational direction of the rotating seal ring <NUM> as indicated by an arrow L2, so that dynamic pressure is generated in the Rayleigh step 9A.

The pressure is the highest in the vicinity of the wall portion 9a which is the end portion on the downstream side of the Rayleigh step 9A, so that the low-pressure side fluid A flows out from the vicinity of the wall portion 9a to the periphery thereof as indicated by an arrow L3. Incidentally, the pressure decreases gradually as the upstream side of the Rayleigh step 9A is approached.

In addition, when the stationary seal ring <NUM> and the rotating seal ring <NUM> rotate relative to each other, the sealed liquid F of a high pressure flows into the gap between the sliding surfaces <NUM> and <NUM> from the outer diameter side thereof at all times to perform so-called fluid lubrication. At this time, since the pressure of the sealed liquid F in the vicinity of the Rayleigh step 9A, as described above, particularly on the downstream side of the Rayleigh step 9A is high, as indicated by an arrow H1, the sealed liquid F remains located on the land <NUM> to hardly enter the Rayleigh step 9A. On the other hand, since the liquid guide groove portion <NUM> is a deep groove portion and communicates with the low-pressure side, as indicated by an arrow H2, the sealed liquid F in the vicinity of the liquid guide groove portion <NUM> easily enters the liquid guide groove portion <NUM>. In addition, since the sealed liquid F is a liquid and has large surface tension, the sealed liquid F moves along side wall surfaces of the liquid guide groove portion <NUM> to easily enter the liquid guide groove portion <NUM>.

Next, an operation in which the sealed liquid F suctioned into the liquid guide groove portion <NUM> flows out to the gap between the sliding surfaces <NUM> and <NUM> will be described.

In a case where almost no sealed liquid F remains in the dynamic pressure generating mechanism <NUM>, when the rotating seal ring <NUM> rotates relative to the stationary seal ring <NUM> (refer to the black arrow of <FIG>), as illustrated in <FIG>, the sealed liquid F which has entered the liquid guide groove portion <NUM> becomes an agglomerated droplet as indicated by reference sign H3. Thereafter, as illustrated in <FIG>, when the droplet reaches a certain volume, as indicated by reference sign H4, the droplet is suctioned into the Rayleigh step 9A due to a relatively low pressure formed on the upstream side of the Rayleigh step 9A. At the same time, the sealed liquid F newly enters the liquid guide groove portion <NUM> to become a droplet H3'. At this time, the sealed liquid F of a larger amount than the amount at an initial stage of the relative rotation in <FIG> enters the liquid guide groove portion <NUM>.

Thereafter, as illustrated in <FIG>, the sealed liquid F suctioned into the Rayleigh step 9A receives a large shearing force from the rotating seal ring <NUM> to move to the downstream side in the Rayleigh step 9A while the pressure increases, as indicated by an arrow H5, to flow out to the vicinity of the wall portion 9a. At the same time, a larger amount of the sealed liquid F newly enters the liquid guide groove portion <NUM> to become a droplet H3'', and as indicated by reference sign H4', the droplet H3' is suctioned into the Rayleigh step 9A.

Thereafter, the amount of the sealed liquid F entering the liquid guide groove portion <NUM> is further increased than in the state illustrated in <FIG>, and a steady state where the sealed liquid F flows out continuously from the Rayleigh step 9A to the gap between the sliding surfaces <NUM> and <NUM> is reached. In the steady state, the sealed liquid F of a high pressure flows into the gap between the sliding surfaces <NUM> and <NUM> from the outer diameter side thereof or the Rayleigh step 9A at all times to perform fluid lubrication as described above. Incidentally, the time until the steady state is reached via the states of <FIG> is a transient short time. In addition, when the sealed liquid F remains in the dynamic pressure generating mechanism <NUM> during stop of the general industrial machine, depending on the amount of the sealed liquid F remaining in the dynamic pressure generating mechanism <NUM>, the operation starts from any one of the state of <FIG>, the state of <FIG>, the state of <FIG>, and the steady state.

Here, since the liquid guide groove portion <NUM> is a deep groove portion and communicates with the low-pressure side, the sealed liquid F indicated by the arrow H5 is easily suctioned into the liquid guide groove portion <NUM> adjacent thereto, so that the amount of the sealed liquid F between the sliding surfaces <NUM> and <NUM> is stable and high lubricity can be maintained. In addition, since a liquid has a larger interfacial tension for a solid than a gas, the sealed liquid F is easily held between the sliding surfaces <NUM> and <NUM>, and the atmosphere is easily discharged to the inner diameter side of the stationary seal ring <NUM> and the rotating seal ring <NUM>.

As described above, when the stationary seal ring <NUM> and the rotating seal ring <NUM> rotate relative to each other, the sealed liquid F which has entered the liquid guide groove portion <NUM> is suctioned into the Rayleigh step 9A, so that dynamic pressure is generated therein. Since the liquid guide groove portion <NUM> has a deep groove depth and a large volume, even when the sealed liquid F is supplied to the low-pressure side of the sliding surface <NUM>, the sealed liquid F is recovered and returned from the Rayleigh step 9A to the gap between the sliding surfaces <NUM> and <NUM>. Therefore, the lubricity can be improved over a wide area of the sliding surface <NUM>. In addition, since the sealed liquid F is recovered by the liquid guide groove portion <NUM> communicating with the low-pressure side on the inner diameter side of the sliding surfaces <NUM> and <NUM>, the amount of the sealed liquid F leaking to the low-pressure side is small.

In addition, since a large amount of the sealed liquid F is held in the liquid guide groove portion <NUM>, the amount of the sealed liquid F suctioned into the Rayleigh step 9A can be sufficiently secured, and even when the amount of the sealed liquid F held in the liquid guide groove portion <NUM> increases or decreases in a short time, the amount of the sealed liquid F suctioned into the Rayleigh step 9A can be substantially constant, and the sliding surfaces <NUM> and <NUM> can be avoided from being subjected to poor lubrication. In addition, since the liquid guide groove portion <NUM> communicates with the low-pressure side, the pressure in the liquid guide groove portion <NUM> is lower than the pressure of the sealed liquid F between the sliding surfaces <NUM> and <NUM>, and the sealed liquid F in the vicinity of the liquid guide groove portion <NUM> is easily suctioned into the liquid guide groove portion <NUM>.

In addition, the liquid guide groove portion <NUM> extends in the radial direction. Specifically, since the liquid guide groove portion <NUM> extends in a direction orthogonal to a center axis of the stationary seal ring <NUM>, and the Rayleigh step 9A is disposed in the circumferential direction from the outer diameter side end portion of the liquid guide groove portion <NUM> to intersect the liquid guide groove portion <NUM>, the liquid guide groove portion <NUM> is unlikely to be affected by the inertia or dynamic pressure of a flow of the sealed liquid F, which is generated in the Rayleigh step 9A. For this reason, the sealed liquid F or the low-pressure side fluid A adhering to an inside surface of the stationary seal ring <NUM> is unlikely to be directly suctioned into the Rayleigh step 9A from the inner diameter side of the liquid guide groove portion <NUM>. In addition, the sealed liquid F can be held in the liquid guide groove portion <NUM> without being directly affected by dynamic pressure.

In addition, the width in the circumferential direction of the liquid guide groove portion <NUM> is shortened, so that a large number of the stationary seal rings <NUM> can be disposed in the circumferential direction. Therefore, the degree of freedom in design is high. Incidentally, the liquid guide groove portion <NUM> is not limited to extending in the direction orthogonal to the center axis of the stationary seal ring <NUM>, and may be inclined from a position orthogonal to the center axis of the stationary seal ring <NUM>. It is preferable that the inclination is less than <NUM> degrees. Further, the shape of the liquid guide groove portion <NUM> can be freely changed to an arc shape or the like.

In addition, since the step <NUM> is formed in the communication part between the Rayleigh step 9A and the liquid guide groove portion <NUM> by the side surface on the downstream side of the liquid guide groove portion <NUM> and the bottom surface of the Rayleigh step 9A, the sealed liquid F can be held in the liquid guide groove portion <NUM> without being directly affected by dynamic pressure.

In addition, since the Rayleigh step 9A communicates with the liquid guide groove portion <NUM> over the entire width in the radial direction, an opening region of the Rayleigh step 9A to the liquid guide groove portion <NUM> can be secured, and the sealed liquid F held in the liquid guide groove portion <NUM> can be efficiently suctioned up.

In addition, the liquid guide groove portion <NUM> communicates with the inner diameter side of the stationary seal ring <NUM>. Namely, the sliding component is an inside mechanical seal, and when the stationary seal ring <NUM> and the rotating seal ring <NUM> rotate relative to each other, the sealed liquid F in the Rayleigh step 9A can return to the high-pressure side due to centrifugal force, and a leakage of the sealed liquid F to the low-pressure side on the inner diameter side of the sliding surfaces <NUM> and <NUM> can be reduced.

In addition, since the dynamic pressure generating mechanism <NUM> is provided in the stationary seal ring <NUM>, when the stationary seal ring <NUM> and the rotating seal ring <NUM> rotate relative to each other, the state inside the liquid guide groove portion <NUM> is easily kept close to atmospheric pressure.

Incidentally, in the first embodiment, a mode in which the liquid guide groove portion <NUM> and the Rayleigh step 9A form an inverted L shape when seen in the direction orthogonal to the sliding surface <NUM> has been provided as an example; however, for example, the liquid guide groove portion <NUM> and the Rayleigh step 9A may smoothly communicate with each other without intersecting each other, to form, for example, a linear shape or an arc shape.

In addition, the step <NUM> may not be provided in the communication part between the liquid guide groove portion <NUM> and the Rayleigh step 9A, for example, the liquid guide groove portion <NUM> and the Rayleigh step 9A may communicate with each other through an inclined surface. In this case, for example, a portion having a depth dimension of <NUM> or less can be the Rayleigh step 9A as a shallow groove portion, and a portion which is deeper than <NUM> can be the liquid guide groove portion <NUM> as a deep groove portion.

In addition, the shallow groove portion is not limited to extending concentrically with the stationary seal ring in the circumferential direction, for example, may be formed in an arc shape such that the end portion on the downstream side faces the high-pressure side. In addition, the shallow groove portion may extend linearly from the deep groove portion, or may extend in a meandering manner.

Next, a sliding component according to a second embodiment of the present invention will be described with reference to <FIG>. Incidentally, the description of configurations which are the same as and duplicated from those in the first embodiment will be omitted.

As illustrated in <FIG>, a dynamic pressure generating mechanism <NUM> provided in a stationary seal ring <NUM> includes the liquid guide groove portion <NUM>, the Rayleigh step 9A, and a reverse Rayleigh step 9B as a shallow groove portion that extends concentrically with the stationary seal ring <NUM> from the outer diameter side end portion of the liquid guide groove portion <NUM> toward the downstream side in the circumferential direction. Namely, the dynamic pressure generating mechanism <NUM> has a T shape when seen in the direction orthogonal to the sliding surface <NUM>. In addition, the reverse Rayleigh step 9B is formed with the same depth dimension of <NUM> as that of the Rayleigh step 9A.

When the rotating seal ring <NUM> rotates counterclockwise on the drawing sheet as indicated by a solid arrow of <FIG>, the low-pressure side fluid A moves in order of arrows L1, L2, and L3, so that dynamic pressure is generated in the Rayleigh step 9A. In addition, when the rotating seal ring <NUM> rotates clockwise on the drawing sheet as indicated by a dotted arrow of <FIG>, the low-pressure side fluid A moves in order of arrows L1, L2', and L3', so that dynamic pressure is generated in the reverse Rayleigh step 9B. Namely, when the rotating seal ring <NUM> rotates clockwise on the drawing sheet of <FIG>, the reverse Rayleigh step 9B functions as a Rayleigh step, and the Rayleigh step 9A functions as a reverse Rayleigh step.

As described above, since the Rayleigh step 9A and the reverse Rayleigh step 9B extend from the liquid guide groove portion <NUM> to both sides in the circumferential direction, and one of the Rayleigh step 9A and the reverse Rayleigh step 9B can be used as a shallow groove portion for generating dynamic pressure, the Rayleigh step 9A or the reverse Rayleigh step 9B can be used regardless of the relative rotational direction of the stationary seal ring <NUM> and the rotating seal ring <NUM>.

In addition, the Rayleigh step 9A of the dynamic pressure generating mechanism <NUM> is adjacent, in the circumferential direction, to the reverse Rayleigh step 9B of a dynamic pressure generating mechanism <NUM>' adjacent thereto. Accordingly, the sealed liquid F which flows out from the vicinity of the wall portion 9a of the Rayleigh step 9A of the dynamic pressure generating mechanism <NUM> to tend to move to the inner diameter side is suctioned from the reverse Rayleigh step 9B of the dynamic pressure generating mechanism <NUM>' adjacent thereto. Therefore, a leakage of the sealed liquid F to the low-pressure side can be reduced.

Incidentally, in the second embodiment, a case where the Rayleigh step 9A and the reverse Rayleigh step 9B have the same depth dimension has been provided as an example; however, the Rayleigh step 9A and the reverse Rayleigh step 9B may be formed with different depth dimensions. In addition, both may be the same or different from each other also in length in the circumferential direction and width in the radial direction.

In addition, the Rayleigh step 9A of the dynamic pressure generating mechanism <NUM> and the reverse Rayleigh step 9B of the dynamic pressure generating mechanism <NUM>' adjacent thereto may be separated from each other by a long distance in the circumferential direction to further increase the pressure which separates the sliding surfaces <NUM> and <NUM> from each other.

Next, a sliding component according to a third embodiment of the present invention will be described with reference to <FIG>. Incidentally, the description of configurations which are the same as and duplicated from those in the second embodiment will be omitted.

As illustrated in <FIG>, a plurality of the dynamic pressure generating mechanisms <NUM> and a plurality of specific dynamic pressure generating mechanisms <NUM> are formed in a stationary seal ring <NUM>. The specific dynamic pressure generating mechanism <NUM> includes a liquid guide groove portion <NUM> communicating with the high-pressure side, a Rayleigh step 17A that extends concentrically with the stationary seal ring <NUM> from an inner diameter side end portion of the liquid guide groove portion <NUM> toward the downstream side in the circumferential direction, and a reverse Rayleigh step 17B that extends concentrically with the stationary seal ring <NUM> from the inner diameter side end portion of the liquid guide groove portion <NUM> toward the upstream side in the circumferential direction. The liquid guide groove portion <NUM> and the liquid guide groove portion <NUM> are formed at positions corresponding to each other in the circumferential direction. In addition, the liquid guide groove portion <NUM> functions as a deep groove portion of the specific dynamic pressure generating mechanism <NUM>, and the Rayleigh step 17A and the reverse Rayleigh step 17B function as shallow groove portions of the specific dynamic pressure generating mechanism <NUM>.

The Rayleigh step 9A and the reverse Rayleigh step 9B of the dynamic pressure generating mechanism <NUM> are formed to be longer in the circumferential direction than the Rayleigh step 17A and the reverse Rayleigh step 17B of the specific dynamic pressure generating mechanism <NUM>. In addition, the Rayleigh step 17A and the reverse Rayleigh step 17B are formed with the same depth dimension of <NUM> as that of the Rayleigh step 9A and the reverse Rayleigh step 9B. In addition, the width in the radial direction of the Rayleigh step 17A and the reverse Rayleigh step 17B is smaller than the width in the radial direction of the Rayleigh step 9A and the reverse Rayleigh step 9B. Namely, the volume of the dynamic pressure generating mechanism <NUM> is larger than the volume of the specific dynamic pressure generating mechanism <NUM>.

When the rotating seal ring <NUM> rotates counterclockwise on the drawing sheet as indicated by a solid arrow of <FIG>, the sealed liquid F moves in order of arrows L11, L12, and L13, so that dynamic pressure is generated in the Rayleigh step 17A. In addition, when the rotating seal ring <NUM> rotates clockwise on the drawing sheet as indicated by a dotted arrow of <FIG>, the sealed liquid F moves in order of arrows L11, L12', and L13', so that dynamic pressure is generated in the reverse Rayleigh step 17B. In such a manner, regardless of the relative rotational direction of the stationary seal ring <NUM> and the rotating seal ring <NUM>, dynamic pressure can be generated in the specific dynamic pressure generating mechanism <NUM>.

In addition, while the dynamic pressure generated in the specific dynamic pressure generating mechanism <NUM> separates the sliding surfaces <NUM> and <NUM> from each other to form an appropriate liquid film therebetween, the sealed liquid F which tends to leak from the sliding surface <NUM> to the low-pressure side can be recovered by the dynamic pressure generating mechanism <NUM>.

In addition, since the volume of the dynamic pressure generating mechanism <NUM> is larger than the volume of the specific dynamic pressure generating mechanism <NUM>, the suctioning force of the Rayleigh step 9A and the reverse Rayleigh step 9B of the dynamic pressure generating mechanism <NUM> is increased, so that a balance in dynamic pressure between the dynamic pressure generating mechanism <NUM> on the low-pressure side and the specific dynamic pressure generating mechanism <NUM> on the high-pressure side can be adjusted.

In addition, since the wall portion 9a which is an end of the dynamic pressure generating mechanism <NUM> and a wall portion 17a which is an end of the specific dynamic pressure generating mechanism <NUM> are shifted from each other in the circumferential direction, the pressure can be distributed with good balance in the circumferential direction of the sliding surfaces <NUM> and <NUM>.

Incidentally, the length in the circumferential direction of the Rayleigh step 9A and the reverse Rayleigh step 9B may be the same as that of the Rayleigh step 17A and the reverse Rayleigh step 17B, or may be shorter than that of the Rayleigh step 17A and the reverse Rayleigh step 17B. In addition, the Rayleigh step 17A and the reverse Rayleigh step 17B may be formed with a depth dimension different from that of the Rayleigh step 9A and the reverse Rayleigh step 9B. In addition, the width in the radial direction of the Rayleigh step 17A and the reverse Rayleigh step 17B may be larger than the width in the radial direction of the Rayleigh step 9A and the reverse Rayleigh step 9B. Preferably, the volume of the dynamic pressure generating mechanism <NUM> may be larger than the volume of the specific dynamic pressure generating mechanism <NUM>.

Next, modification examples of the specific dynamic pressure generating mechanism will be described. As illustrated in <FIG>, a specific dynamic pressure generating mechanism of a first modification example is a dimple <NUM> having a circular recess shape when seen in the direction orthogonal to the sliding surface <NUM>. Incidentally, the shape, number, disposition, and the like of the dimples <NUM> can be freely changed.

In addition, as illustrated in <FIG>, a specific dynamic pressure generating mechanism of a second modification example includes arc grooves <NUM> and <NUM> that extend in an arc shape while being inclined in the radial direction. Specifically, outer diameter side end portions of the arc grooves <NUM> and <NUM> communicate with the high-pressure side. A plurality of the arc grooves <NUM> are provided on the outer diameter side of the Rayleigh step 9A, and a plurality of the arc grooves <NUM> are provided on the outer diameter side of the reverse Rayleigh step 9B.

In addition, the arc groove <NUM> has a shape such that when the rotating seal ring <NUM> rotates counterclockwise on the drawing sheet of <FIG>, the sealed liquid F moves toward the inner diameter side, and the arc groove <NUM> has a shape such that when the rotating seal ring <NUM> rotates clockwise on the drawing sheet of <FIG>, the sealed liquid F moves toward the inner diameter side. When the rotating seal ring <NUM> rotates counterclockwise, the pressure on the inner diameter side of the arc groove <NUM> increases, and when the rotating seal ring <NUM> rotates clockwise, the pressure on the inner diameter side of the arc groove <NUM> increases. Therefore, the sliding surfaces <NUM> and <NUM> can be separated from each other to form an appropriate liquid film therebetween. Incidentally, the shape, number, disposition, and the like of the arc grooves <NUM> and <NUM> can be freely changed.

Next, a sliding component according to a fourth embodiment of the present invention will be described with reference to <FIG>. Incidentally, the description of configurations which are the same as and duplicated from those in the second embodiment will be omitted.

As illustrated in <FIG>, a stationary seal ring <NUM> is provided to be shifted from the dynamic pressure generating mechanism <NUM> in the circumferential direction such that the specific dynamic pressure generating mechanism <NUM> is located between the dynamic pressure generating mechanisms <NUM> adjacent to each other. The specific dynamic pressure generating mechanism <NUM> overlaps, in the radial direction, the dynamic pressure generating mechanisms <NUM> adjacent thereto. Accordingly, the sealed liquid F circulates such that the sealed liquid F which has flowed out from an end portion on the downstream side of the Rayleigh step 17A of the specific dynamic pressure generating mechanism <NUM> is suctioned into the reverse Rayleigh step 9B of the dynamic pressure generating mechanism <NUM>, and the sealed liquid F which has flowed out from the downstream side of the Rayleigh step 9A of the dynamic pressure generating mechanism <NUM> is suctioned into the reverse Rayleigh step 17B of the specific dynamic pressure generating mechanism <NUM>. Therefore, a liquid film can be stably formed between the sliding surfaces <NUM> and <NUM>.

In addition, since the wall portion 9a which is an end of the dynamic pressure generating mechanism <NUM> and a wall portion 17a which is an end of the specific dynamic pressure generating mechanism <NUM> are shifted from each other in the circumferential direction, the pressure can be distributed with good balance in the circumferential direction of the sliding surfaces <NUM> and <NUM>. Further, the sealed liquid F which has flowed out from the end portion on the downstream side of the Rayleigh step 17A of the specific dynamic pressure generating mechanism <NUM> can be efficiently recovered by the liquid guide groove portion <NUM> of the dynamic pressure generating mechanism <NUM>.

Next, a sliding component according to a fifth embodiment of the present invention will be described with reference to <FIG>. Incidentally, the description of configurations which are the same as and duplicated from those in the second embodiment will be omitted.

As illustrated in <FIG>, in a specific dynamic pressure generating mechanism <NUM>, a Rayleigh step 171A and a reverse Rayleigh step 171B are formed from an outer diameter side end portion of the liquid guide groove portion <NUM>, and the Rayleigh step 171A and the reverse Rayleigh step 171B communicate with the high-pressure side.

Next, a sliding component according to a sixth embodiment of the present invention will be described with reference to <FIG>. Incidentally, the description of configurations which are the same as and duplicated from those in the second embodiment will be omitted.

A mechanical seal illustrated in <FIG> is an outside mechanical seal that seals the sealed liquid F which tends to leak from an inner diameter side of sliding surfaces toward an outer diameter side. The dynamic pressure generating mechanism <NUM> is disposed on the outer diameter side to communicate with a low-pressure side, and the specific dynamic pressure generating mechanism <NUM> is disposed on the inner diameter side to communicate with a high-pressure side. Incidentally, even in the outside mechanical seal, the dynamic pressure generating mechanism may be formed in an inverted L shape or an L shape corresponding to one rotational direction as in the first embodiment, and modification examples to be described later of the dynamic pressure generating mechanism may be applied. In addition, the specific dynamic pressure generating mechanism may not be provided as in the first embodiment, or the specific dynamic pressure generating mechanism may be formed as illustrated in <FIG>.

Next, modification examples of the dynamic pressure generating mechanisms of the first to fifth embodiments will be described based on <FIG>.

As illustrated in <FIG>, in a dynamic pressure generating mechanism <NUM> of a third modification example, a Rayleigh step 91A and a reverse Rayleigh step 91B extend from a central portion in the radial direction of the liquid guide groove portion <NUM> in the circumferential direction. Accordingly, the liquid guide groove portion <NUM> further extends to the outer diameter side than the Rayleigh step 91A and the reverse Rayleigh step 91B. Therefore, the sealed liquid F on the outer diameter side can easily enter the liquid guide groove portion <NUM>, and a large amount of the sealed liquid F can be stored in the liquid guide groove portion <NUM>.

In addition, as illustrated in <FIG>, in a dynamic pressure generating mechanism <NUM> of a fourth modification example, a groove <NUM> as a shallow groove portion which is shifted to the outer diameter side of the liquid guide groove portion <NUM> as a deep groove portion to extend in the circumferential direction is formed in an arc shape, and the dynamic pressure generating mechanism <NUM> has a T shape when seen in the direction orthogonal to the sliding surface <NUM>. Accordingly, the sealed liquid F can be directly supplied from a reverse Rayleigh step which is a portion of the groove <NUM> upstream of the liquid guide groove portion <NUM> to a Rayleigh step which is a portion downstream of the liquid guide groove portion <NUM>. Incidentally, the position of the shallow groove portion in the deep groove portion can be freely changed as long as the shallow groove portion and the deep groove portion communicate with each other.

In addition, as illustrated in <FIG>, in a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of a fifth modification example, the width in the circumferential direction of an outer diameter side end portion 151a communicating with the Rayleigh step 9A and the reverse Rayleigh step 9B is smaller than that of an inner diameter side end portion 151b thereof. Accordingly, the inner diameter side end portion 151b is formed to be wider in the circumferential direction than the outer diameter side end portion 151a. Therefore, the sealed liquid F adhering to a surface closer to the inside than the sliding surface <NUM> is easily suctioned into the liquid guide groove portion <NUM>.

In addition, as illustrated in <FIG>, in a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of a sixth modification example, the depth dimension of an inner diameter side end portion 152b is larger than the depth dimension of an outer diameter side end portion 152a. Accordingly, a step is formed in a communication part between the inner diameter side end portion 152b and the outer diameter side end portion 152a. Therefore, the sealed liquid F held in the inner diameter side end portion 152b is unlikely to flow out to the low-pressure side.

In addition, as illustrated in <FIG>, a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of a seventh modification example includes a first portion 153b that is located closer to the inner diameter side than the Rayleigh step 9A and the reverse Rayleigh step 9B, and a second portion 153a that is formed to be narrower in the circumferential direction than the first portion 153b, and extends to the outer diameter side of the first portion 153b. The Rayleigh step 9A and the reverse Rayleigh step 9B communicate with an outer diameter side end portion of the second portion 153a, and are provided to be separated to the outer diameter side from the first portion 153b.

In addition, as illustrated in <FIG>, in a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of an eighth modification example, a second portion 154a communicating with the Rayleigh step 9A and the reverse Rayleigh step 9B is formed with a larger width in the circumferential direction than that of a first portion 154b located on the inner diameter side thereof. Incidentally, the first portion 154b, and the Rayleigh step 9A and the reverse Rayleigh step 9B have the same width in the radial direction, and communicate with each other over the entire width. Accordingly, the first portion 154b is narrower in width than the second portion 154a. Therefore, the sealed liquid F held in the second portion 154a on the outer diameter side is unlikely to flow out to the low-pressure side.

In addition, as illustrated in <FIG>, in a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of a ninth modification example, a portion communicating with the Rayleigh step 9A and the reverse Rayleigh step 9B is tapered toward the outer diameter side. Accordingly, the sealed liquid F can be guided to the outer diameter side of the liquid guide groove portion <NUM>.

In addition, as illustrated in <FIG>, in a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of a tenth modification example, a portion located closer to the inner diameter side than the Rayleigh step 9A and the reverse Rayleigh step 9B is tapered toward the inner diameter side. Accordingly, the sealed liquid F held in the liquid guide groove portion <NUM> is unlikely to flow out to the low-pressure side.

In addition, as illustrated in <FIG>, in a liquid guide groove portion <NUM> of a dynamic pressure generating mechanism <NUM> of an eleventh modification example, a portion located closer to the inner diameter side than the Rayleigh step 9A and the reverse Rayleigh step 9B has an arc shape, and is formed to further bulge in the circumferential direction than a portion communicating with the Rayleigh step 9A and the reverse Rayleigh step 9B. Since a portion on the inner diameter side of the liquid guide groove portion <NUM> is a curved surface, the sealed liquid F can flow smoothly.

In addition, as illustrated in <FIG>, in the stationary seal ring <NUM> of a twelfth modification example, the dynamic pressure generating mechanisms <NUM> and dynamic pressure generating mechanisms <NUM> are alternately provided in the circumferential direction. The dynamic pressure generating mechanism <NUM> includes a liquid guide groove portion <NUM>, and the reverse Rayleigh step 9B that extends from an outer diameter side end portion of the liquid guide groove portion <NUM> to the downstream side in the circumferential direction. Namely, the dynamic pressure generating mechanism <NUM> has an L shape when seen in the direction orthogonal to the sliding surface <NUM>. Accordingly, the above configuration can be used without being limited by the rotational direction of the rotating seal ring <NUM>.

The embodiments of the present invention have been described above with reference to the drawings; however, the specific configuration is not limited to the embodiments, and the present invention also includes changes or additions that are made without departing from the concept of the present invention.

For example, in the embodiments, as an example of the sliding component, the mechanical seal for a general industrial machine has been described, but the present invention may be applied to other mechanical seals for an automobile, a water pump, and the like. In addition, the present invention is not limited to the mechanical seal, and may be applied to a sliding component such as a slide bearing other than the mechanical seal.

In addition, in the embodiments, an example where the dynamic pressure generating mechanism is provided only in the stationary seal ring has been described; however, the dynamic pressure generating mechanism may be provided only in the rotating seal ring <NUM>, or may be provided in both the stationary seal ring and the rotating seal ring.

In addition, in the embodiments, a mode in which the sliding component is provided with the plurality of dynamic pressure generating mechanisms having the same shape has been provided as an example; however, a plurality of dynamic pressure generating mechanisms having different shapes may be provided. In addition, the interval between the dynamic pressure generating mechanism, the number of the dynamic pressure generating mechanisms, or the like can be appropriately changed.

Claim 1:
A sliding component (<NUM>, <NUM>) that has an annular shape and is disposed in a place where relative rotation is performed in a rotary machine, comprising a plurality of dynamic pressure generating mechanisms (<NUM>, <NUM>),
wherein the plurality of dynamic pressure generating mechanisms (<NUM>, <NUM>) are provided in a sliding surface (<NUM>) of the sliding component (<NUM>, <NUM>), each of the dynamic pressure generating mechanisms (<NUM>, <NUM>) including a deep groove portion (<NUM>) that communicates with a leakage side, and at least one shallow groove portion (9A, 9B) that communicates with the deep groove portion (<NUM>) and extends in a circumferential direction, the shallow groove portion (9A, 9B) being shallower than the deep groove portion (<NUM>),
the sliding surface (<NUM>) of the sliding component (<NUM>, <NUM>) is provided with a specific dynamic pressure generating mechanism (<NUM>) that is disposed on a sealed fluid side with respect to the dynamic pressure generating mechanism (<NUM>, <NUM>) and is independent of the dynamic pressure generating mechanism (<NUM>, <NUM>),
characterized in that the volume of the dynamic pressure generating mechanism (<NUM>, <NUM>) is larger than the volume of the specific dynamic pressure generating mechanism (<NUM>).