Patent Description:
A mechanical seal as an example of a shaft sealing device preventing sealing target liquid leakage includes a pair of annular sliding components rotating relative to each other and having sliding surfaces sliding with each other. In recent years and in such mechanical seals, it has been desired for environmental measures or the like to reduce the energy that is lost due to sliding. In this regard, the sliding surface of the sliding component may be provided with a positive pressure generation groove communicating with the high-pressure sealing target liquid side and blocked at one end on the sliding surface.

For example, in the mechanical seal that is illustrated in Patent Citation <NUM>, a plurality of positive pressure generation grooves having an opening portion communicating with a sealing target fluid side and extending at an angle to the rotation-direction downstream side while facing the atmospheric side are disposed along the circumferential direction in the sliding surface of one sliding component. According to this, during the relative rotation of the sliding component, the sealing target liquid is introduced into the positive pressure generation groove, the sealing target liquid concentrates on the leading edge portion positioned at the downstream-side leading edge of the positive pressure generation groove, and positive pressure generation and inter-sliding surface liquid film generation occur as a result. In addition, the sliding surfaces are slightly separated from each other, and thus lubricity is improved and friction reduction is realized.

In addition, in the mechanical seal illustrated in Patent Citation <NUM>, a plurality of V-shaped grooves forming a V shape with tip portions facing the rotation-direction downstream side are disposed over the circumferential direction in the sliding surface of one sliding component. The side that communicates with a sealing target liquid side as one of the two sides constituting the V-shaped groove functions as a positive pressure generation groove, and the tip portion where the two sides of the V-shaped groove intersect is positioned
in the leading edge portion on the downstream side in the relative rotation direction. According to this, the sealing target liquid concentrates on the tip portion of the V-shaped groove, a liquid film of the sealing target liquid is formed, and lubricity is improved as in Patent Citation <NUM>.

A further sliding component is described in Patent Citation <NUM>, with which it is possible to improve lubrication by actively introducing a fluid to a sliding surface when from startup to normal operating state, prevent the deposition of wear particles and contaminants within sliding surfaces, and prevent the occurrence of wear of and leakage from sliding surfaces. The sliding component comprises a pair of sliding components which slide relative to one another. These sealing rings have a sliding surface formed in the radial direction, and seal against leakages of liquid or mist-form fluids which are the fluids being sealed, and comprise, on at least one of the sliding surfaces: a positive pressure-generating mechanism having a positive pressure-generating groove which is connected with the sealed fluid-side edge of the sliding surface, and which is not connected to the leakage-side edge; and a discharge groove which is provided in an inclined manner such that the upstream-side end is positioned on the leakage side and the downstream-side end is positioned on the sealed fluid side.

Further different configurations of sliding components can also be found in Patent Citations <NUM> to <NUM>.

However, in Patent Citation <NUM>, the leading edge portions of the plurality of positive pressure generation grooves disposed along the circumferential direction of the sliding surface are at the same position in the radial direction. In other words, the plurality of leading edge portions line up on the same circumference with exception. Likewise, in Patent Citation <NUM>, the tip portions of the plurality of V-shaped grooves disposed along the circumferential direction of the sliding surface line up on the same circumference with exception. Accordingly, in Patent Citations <NUM> and <NUM>, positive pressure is generated around the leading edge portions and the tip portions lining up on the same circumference, and thus the radial pressure gradient of the sliding surface becomes large and it becomes difficult to form a uniform liquid film in the wide region of the sliding surface. As a result, high lubricity may not be obtained on the entire sliding surface and the sliding surface may be poorly lubricated. In addition, in Patent Citation <NUM>, the liquid film of the sealing target liquid is formed around the tip portions lining up on the same circumference, and thus the gas-liquid interface between the sealing target liquid on the sealing target liquid side and the atmosphere on the leak side is problematically fixed in a specific narrow range in the radial direction during the relative rotation of the sliding component.

The present invention has been made in view of such problems, and an object of the present invention is to provide a sliding component capable of obtaining high lubricity over the entire surface of a sliding surface.

In order to solve the above problem, sliding components according to the present invention are sliding components for a shaft sealing device shaft-sealing a rotary shaft of a rotating machine, wherein the sliding components are configured to rotate relative to each other and formed in an annular shape and disposed at a relative rotation point of a rotating machine, the sliding component including a plurality of first positive pressure generation grooves arranged side by side in a circumferential direction on a sliding surface of the sliding components, the plurality of first positive pressure generation grooves being configured for generating positive pressure by a sealing target fluid on a sealing target fluid side which is introduced during the relative rotation of the sliding component, the first positive pressure generation grooves having a plurality of leading edge portions at leading edges on a downstream side in a direction of the relative rotation, the plurality of leading edge portions being arranged side by side in the circumferential direction, at least part of the plurality of leading edge portions being disposed at different radial positions, wherein each of the plurality of first positive pressure generation grooves extends at an angle to the downstream side in the relative rotation direction while facing a leak side, and the sliding surface is provided with a negative pressure generation groove extending so as to be continuous from a leak-side end portion of each of the plurality of first positive pressure generation grooves and at an angle to an upstream side in the relative rotation direction while facing the leak side. According to the aforesaid feature of the present invention, during the relative rotation of the sliding component, the sealing target fluid flows to the relative rotation-direction downstream side of each of the first positive pressure generation groove and concentrates on the leading edge portion, leading to positive pressure generation. Since the leading edge portions of the first positive pressure generation grooves are disposed at different radial positions at least in part, the positive pressure on the sliding surface is generated at different radial positions along the circumferential direction. Since the radial pressure gradient on the sliding surface becomes small, a uniform liquid film is likely to be formed in the wide region of the sliding surface. Accordingly, the lubricity of the sliding surface attributable to the sealing target fluid is improved.

It may be preferable that the plurality of leading edge portions arranged side by side are be regularly disposed along the circumferential direction. According to this preferable configuration, the fluid film of the sealing target fluid is formed at regularly disposed positions during the relative rotation of the sliding component, and thus the lubricity is improved.

It may be preferable that the plurality of leading edge portions arranged side by side have radial positions gradually changing along the circumferential direction and be disposed in a wave shape. According to this preferable configuration, the fluid film of the sealing target fluid is formed in a wave shape during the relative rotation of the sliding component, and thus the lubricity is improved.

It may be preferable that each of the plurality of first positive pressure generation grooves has an opening portion communicating with the sealing target fluid side. According to this preferable configuration, during the relative rotation of the sliding component, the sealing target fluid is easily introduced from the sealing target fluid side in the opening portion of the first positive pressure generation groove, and thus the fluid film of the sealing target fluid is easily formed in the leading edge portion and the lubricity of the sliding surface is improved.

According to the present invention each of the plurality of first positive pressure generation grooves extends at an angle to the downstream side in the relative rotation direction while facing a leak side, and the sliding surface is provided with a negative pressure generation groove extending so as to be continuous from a leak-side end portion of each of the plurality of first positive pressure generation grooves and at an angle to an upstream side in the relative rotation direction while facing the leak side. According to this preferable configuration, during the relative rotation of the sliding component, the fluid film of the sealing target fluid formed in the leading edge portion is suctioned in by the negative pressure generation groove with a relatively negative pressure, and thus it is possible to prevent the sealing target fluid from leaking to the leak side and improve the sealability of the sliding component.

It may be preferable that a land extending over the circumferential direction is provided on the leak side of the sliding surface as compared with the negative pressure generation groove. According to this preferable configuration, the leak-side end portion of the negative pressure generation groove is blocked by the land, and thus it is possible to prevent the sealing target fluid from leaking to the leak side when the sliding component is stationary.

It may be preferable that the land on the leak side as compared with the negative pressure generation groove has a constant radial width over the circumferential direction. According to this preferable configuration the radial position of the leak-side end portion of the negative pressure generation groove is constant over the circumferential direction, and thus manufacturing is facilitated.

It may be preferable that the plurality of leading edge portions arranged side by side and a bent portion on the upstream side in the relative rotation direction where the first positive pressure generation groove and the negative pressure generation groove intersect, have radial positions gradually changing along the circumferential direction and be disposed in a wave shape. According to this preferable configuration, the leading edge portion and the bent portion are disposed on a wave-shaped virtual curve, and thus manufacturing is facilitated.

In an embodiment, not belonging to the present invention the sliding surface is provided with a second positive pressure generation groove independent of the first positive pressure generation groove on a leak side as compared with the first positive pressure generation groove and generating positive pressure by a fluid on the leak side as compared with the first positive pressure generation groove being introduced during the relative rotation of the rotating machine and the second positive pressure generation groove is provided with a leading edge portion at the leading edge on the downstream side in the relative rotation direction. According to this preferable configuration, during the relative rotation of the sliding component, the fluid on the leak side flows to the relative rotation-direction downstream side of the second positive pressure generation groove and concentrates on the leading edge portion of the second positive pressure generation groove to lead to positive pressure generation, and thus it is possible to repel the sealing target fluid approaching the vicinity of the leading edge portion of the second positive pressure generation groove from the sealing target fluid side and prevent the sealing target fluid from leaking to the leak side.

In an embodiment, not belonging to the present invention the second positive pressure generation groove is disposed so as to correspond in number and position to the first positive pressure generation groove. According to this preferable configuration, the second positive pressure generation grooves can be machined in accordance with the number and positions of the first positive pressure generation grooves and are easy to manufacture.

In an embodiment, not belonging to the present invention a land extending over the circumferential direction is provided between the first positive pressure generation groove and the second positive pressure generation groove in the radial direction. According to this preferable configuration, the first positive pressure generation groove and the second positive pressure generation groove can be separated from each other and the functions of both during the relative rotation can be clarified.

In an embodiment, not belonging to the present invention the land provided between the first positive pressure generation groove and the second positive pressure generation groove in the radial direction has a radial width constant over the circumferential direction. According to this preferable configuration, the leading edge portion of the second positive pressure
generation groove is separated from the leading edge portion to the leak side by a constant dimension. The leading edge portion of the second positive pressure generation groove where positive pressure is generated during the relative rotation is disposed at positions with different diameter lengths in the circumferential direction, and thus it is possible to prevent the sealing target fluid flowing from the fluid film generated in the leading edge portion of the first positive pressure generation groove during the relative rotation from entering the leak side.

It may be preferable that the plurality of leading edge portions arranged side by side and a corner portion positioned on a relative rotation-direction upstream side of a leak-side end portion of the first positive pressure generation groove have radial positions gradually changing along the circumferential direction and be disposed in a wave shape. According to this preferable configuration, the leading edge portion and the corner portion are disposed on a wave-shaped virtual curve, and thus manufacturing is facilitated.

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

The sliding component according to the first embodiment of the present invention will be described with reference to <FIG>. It should be noted that a mode in which the sliding component is a mechanical seal will be described as an example in the present embodiment. In addition, in the following description, the outer diameter side of the sliding component constituting the mechanical seal is a sealing target liquid side (high-pressure side) and the inner diameter side is an atmospheric side (leak side, low-pressure side). It should be noted that the present invention is not limited thereto, the sealing target liquid side may be the low-pressure side and the leak side may be the high-pressure side, and the sealing target fluid is not limited to a liquid and may be a gas, examples of which include the atmosphere. In addition, for convenience of description, dots may be added to, for example, the grooves formed in the sliding surface in the drawings.

The mechanical seal for general industrial machine illustrated in <FIG> is an inside-type mechanical seal that seals a sealing target liquid F to leak toward the atmospheric side from the sealing target liquid side of a sliding surface. The mechanical seal mainly includes a rotating seal ring <NUM>, which is an annular sliding component provided on a rotary shaft <NUM> in a state of being rotatable together with the rotary shaft <NUM> via a sleeve <NUM>, and an annular stationary seal ring <NUM>, which is a sliding component provided on a seal cover <NUM> fixed to a housing <NUM> of an attachment target device in a nonrotating state and a state of being movable in the axial direction. A sliding surface <NUM> of the stationary seal ring <NUM> and a sliding surface <NUM> of the rotating seal ring <NUM> slide closely with each other by a bellows <NUM> urging the stationary seal ring <NUM> in the axial direction. It should be noted that the sliding surface <NUM> of the rotating seal ring <NUM> may form a flat surface or may be provided with a recessed portion.

The stationary seal ring <NUM> and the rotating seal ring <NUM> are typically formed of a combination of SiC (hard material) or a combination of SiC (hard material) and carbon (soft material). However, the present invention is not limited thereto and any sliding material can be applied insofar as it is used as a sliding material for a mechanical seal. It should be noted that the SiC includes a sintered body using boron, aluminum, carbon, or the like as a sintering aid and a material made of two or more types of phases having different components and compositions, examples of which include SiC in which graphite particles are dispersed, reaction-sintered SiC made of SiC and Si, SiC-TiC, and SiC-TiN. As the carbon, resin-molded carbon, sintered carbon, and the like can be used, including carbon in which carbon and graphite are mixed. In addition to the above sliding materials, a metal material, a resin material, a surface modification material (coating material), a composite material, and the like can also be applied.

As illustrated in <FIG>, the rotating seal ring <NUM> slides relative to the stationary seal ring <NUM> as indicated by the arrow and a plurality of dynamic pressure generation mechanisms <NUM> are evenly arranged along the circumferential direction of the stationary seal ring <NUM> on the sliding surface <NUM> of the stationary seal ring <NUM>. The part of the sliding surface <NUM> other than the dynamic pressure generation mechanism <NUM> is a land <NUM> forming a flat surface.

Next, the dynamic pressure generation mechanism <NUM> will be outlined with reference to <FIG> and <FIG>. It should be noted that the left side of the page of <FIG> is the downstream side of the sealing target liquid F and the right side of the page of <FIG> is the upstream side of the sealing target liquid F in the following description, when the stationary seal ring <NUM> and the rotating seal ring <NUM> are relatively rotated.

The dynamic pressure generation mechanism <NUM> has a positive pressure generation groove <NUM> provided with an opening portion 15a open to and communicating with the sealing target liquid side, inclined to the downstream side while facing the atmospheric side, and linearly recessed to an atmosphere-side end portion 9b blocked as a leak-side end portion. A leading edge portion 9a is disposed at the downstream-side leading edge of the atmosphere-side end portion 9b. The land <NUM> is provided on the atmospheric side as compared with the positive pressure generation groove <NUM>, and thus it is possible to prevent the sealing target liquid F from leaking to the atmospheric side when the rotating seal ring <NUM> is stationary. In addition, the radial positions of the leading edge portions 9a of a plurality of the positive pressure generation grooves <NUM> arranged side by side gradually change along the circumferential direction and the leading edge portions 9a are disposed on a smooth and continuous virtual curve C having a sine wave shape over the circumferential direction. It should be noted that the present invention is not limited to the present embodiment. Although not particularly illustrated, a corner portion 9c positioned on the upstream side of the atmosphere-side end portion 9b of the positive pressure generation groove <NUM> as well as the leading edge portion 9a may be disposed on the virtual curve C. Further, it should be noted that the virtual curve C has periodicity, the present invention is not limited thereto, and the virtual curve C may lack periodicity.

It should be noted that the plurality of positive pressure generation grooves <NUM> are provided such that the opening portions 15a are evenly disposed along the circumferential direction and the inclination angles of the positive pressure generation grooves <NUM> are different and thus the plurality of positive pressure generation grooves <NUM> can be arranged side by side in a narrow region. However, the present invention is not limited thereto. The plurality of positive pressure generation grooves <NUM> may be provided such that the opening portions 15a are unevenly disposed along the circumferential direction and the inclination angles of the positive pressure generation grooves <NUM> are constant.

Next, the operation of the stationary seal ring <NUM> and the rotating seal ring <NUM> during the relative rotation will be described. First, during the non-operation of a general industrial machine and non-rotation of the rotating seal ring <NUM>, capillarity causes the sealing target liquid F on the sealing target liquid side as compared with the sliding surfaces <NUM> and <NUM> to slightly enter between the sliding surfaces <NUM> and <NUM> and the dynamic pressure generation mechanism <NUM> is filled with the sealing target liquid F that has flowed in from the opening portion 15a of the positive pressure generation groove <NUM>. It should be noted that the sealing target liquid F is higher in viscosity than a gas and thus the amount of leakage from the dynamic pressure generation mechanism <NUM> to the atmospheric side is extremely small when the general industrial machine is stopped.

Next, when the rotating seal ring <NUM> rotates with respect to the stationary seal ring <NUM> as illustrated in <FIG>, the flow of the sealing target liquid F on the sealing target liquid side introduced from the opening portion 15a of the positive pressure generation groove <NUM> toward the leading edge portion 9a is generated as indicated by an arrow H1. Accordingly, dynamic pressure is generated in the positive pressure generation groove <NUM>. It should be noted that the positive pressure in the positive pressure generation groove <NUM> gradually increases from the opening portion 15a side, which is the upstream side, toward the leading edge portion 9a on the downstream side.

In other words, the pressure is highest in the vicinity of the leading edge portion 9a positioned at the downstream-side leading edge of the positive pressure generation groove <NUM>, the sliding surfaces <NUM> and <NUM> are separated from each other, and a liquid film of the sealing target liquid F is formed on the sealing target liquid side between the sliding surfaces <NUM> and <NUM> by the sealing target liquid F flowing out from the vicinity of the leading edge portion 9a between the sliding surfaces <NUM> and <NUM> therearound as indicated by an arrow H2. According to this, the liquid film of the sealing target liquid F is formed in the vicinity of the leading edge portions 9a of the plurality of positive pressure generation grooves <NUM>, and thus so-called fluid lubrication occurs between the sliding surfaces <NUM> and <NUM>, lubricity is improved, and friction reduction is realized. It should be noted that the sealing target liquid F slightly flows out to the downstream side from the point of the positive pressure generation groove <NUM> other than the leading edge portion 9a.

In addition, since a plurality of the leading edge portions 9a are disposed on the sine wave-shaped virtual curve C as described above, the positive pressure on the sliding surface <NUM> during the relative rotation of the rotating seal ring <NUM> is generated at different radial positions along the circumferential direction, the radial pressure gradient on the sliding surface <NUM> becomes small, and thus the liquid film is likely to be formed substantially uniformly in the wide region of the sliding surface <NUM>. Accordingly, the lubricity of the sliding surface <NUM> attributable to the sealing target liquid F is improved.

In addition, the sealing target liquid F that has flowed out from the positive pressure generation groove <NUM> to the land <NUM> as described above flows into another positive pressure generation groove <NUM> arranged side by side on the downstream side as compared with the positive pressure generation groove <NUM> as indicated by an arrow H3. As a result, the internal pressure of the positive pressure generation groove <NUM> can be stabilized.

As described above, the plurality of leading edge portions 9a arranged side by side in the circumferential direction are disposed at different radial positions at least in part. Accordingly, during the relative rotation of the rotating seal ring <NUM>, the sealing target liquid F flows to the relative rotation-direction downstream side of each positive pressure generation groove <NUM> and concentrates on the leading edge portion 9a, leading to positive pressure generation. Since the leading edge portions 9a of the positive pressure generation grooves <NUM> are disposed at different radial positions at least in part, the positive pressure on the sliding surface <NUM> is generated at different radial positions along the circumferential direction. Since the radial pressure gradient on the sliding surface <NUM> becomes small, the liquid film is likely to be formed substantially uniformly in the wide region of the sliding surface <NUM>. Accordingly, the lubricity of the sliding surface <NUM> attributable to the sealing target liquid F is improved.

In addition, the plurality of leading edge portions 9a arranged side by side are regularly disposed along the circumferential direction. As a result, the fluid film of the sealing target liquid F is formed at regularly disposed positions during the relative rotation of the rotating seal ring <NUM>, and thus the lubricity is improved.

In addition, the radial positions of the plurality of leading edge portions 9a arranged side by side gradually change along the circumferential direction and the leading edge portions 9a are disposed in a wave shape. As a result, the liquid film of the sealing target liquid F is formed in a wave shape during the relative rotation of the rotating seal ring <NUM>, and thus the lubricity is improved.

In addition, the positive pressure generation groove <NUM> has the opening portion 15a communicating with the sealing target liquid side. As a result, during the relative rotation of the rotating seal ring <NUM>, the sealing target liquid F is easily introduced from the sealing target liquid side in the leading edge portion 9a of the positive pressure generation groove <NUM>, and thus the liquid film of the sealing target liquid F is easily formed in the leading edge portion 9a and the lubricity of the sliding surface <NUM> is improved.

Next, the sliding component according to the second embodiment of the present invention will be described with reference to <FIG>. It should be noted that configurations identical to those of the first embodiment will not be described below so that redundancy can be avoided.

As illustrated in <FIG> and <FIG>, on the sliding surface <NUM> of a stationary seal ring <NUM>, a plurality of dynamic pressure generation mechanisms <NUM> forming a V shape with tip portions facing downstream are evenly arranged in the circumferential direction of the stationary seal ring <NUM>. The side that is open to and communicates with the sealing target liquid side as one of the two sides constituting the V shape of the dynamic pressure generation mechanism <NUM> corresponds to the positive pressure generation groove <NUM> inclined to the downstream side while facing the atmospheric side and linearly recessed. The other side continuous with the positive pressure generation groove <NUM> corresponds to a negative pressure generation groove <NUM> inclined to the upstream side while facing the atmospheric side and linearly recessed to an atmosphere-side end portion 171a blocked as a leak-side end portion. In addition, the tip portion where the two sides of the V shape intersect corresponds to the leading edge portion 9a. In addition, the radial positions of the leading edge portions 9a of the plurality of positive pressure generation grooves <NUM> arranged side by side gradually change along the circumferential direction and the leading edge portions 9a are disposed on the smooth and continuous virtual curve C having a sine wave shape over the circumferential direction.

Next, the operation of the rotating seal ring <NUM> during the relative rotation will be described. First, during the non-operation of a general industrial machine and non-rotation of the rotating seal ring <NUM>, capillarity causes the sealing target liquid F on the sealing target liquid side as compared with the sliding surfaces <NUM> and <NUM> to slightly enter between the sliding surfaces <NUM> and <NUM> and the dynamic pressure generation mechanism <NUM> is filled with the sealing target liquid F that has flowed in from the opening portion 15a of the positive pressure generation groove <NUM>. It should be noted that the sealing target liquid F is higher in viscosity than a gas and thus the amount of leakage from the dynamic pressure generation mechanism <NUM> to the atmospheric side is extremely small when the general industrial machine is stopped.

Next, when the rotating seal ring <NUM> rotates with respect to the stationary seal ring <NUM> as illustrated in <FIG>, the flow of the sealing target liquid F on the sealing target liquid side introduced from the opening portion 15a of the positive pressure generation groove <NUM> toward the leading edge portion 9a is generated as indicated by the arrow H1. Accordingly, dynamic pressure is generated in the positive pressure generation groove <NUM>. It should be noted that the positive pressure in the positive pressure generation groove <NUM> gradually increases from the opening portion 15a side, which is the upstream side, toward the leading edge portion 9a on the downstream side.

In other words, the pressure is highest in the vicinity of the leading edge portion 9a positioned at the downstream-side leading edge of the positive pressure generation groove <NUM>, the sliding surfaces <NUM> and <NUM> are separated from each other, and a liquid film of the sealing target liquid F is formed on the sealing target liquid side between the sliding surfaces <NUM> and <NUM> by the sealing target liquid F flowing out from the vicinity of the leading edge portion 9a between the sliding surfaces <NUM> and <NUM> therearound as indicated by the arrow H2. According to this, the liquid film of the sealing target liquid F is formed in the vicinity of the leading edge portions 9a of the plurality of positive pressure generation grooves <NUM>, and thus so-called fluid lubrication occurs between the sliding surfaces <NUM> and <NUM>, lubricity is improved, and friction reduction is realized. It should be noted that the sealing target liquid F slightly flows out to the downstream side from the point of the positive pressure generation groove <NUM> other than the leading edge portion 9a.

In addition, since the plurality of leading edge portions 9a are disposed on the sine wave-shaped virtual curve C as described above, the positive pressure on the sliding surface <NUM> during the relative rotation of the rotating seal ring <NUM> is generated at different radial positions along the circumferential direction, the radial pressure gradient on the sliding surface <NUM> becomes small, and thus the liquid film is likely to be formed substantially uniformly in the wide region of the sliding surface <NUM>. Accordingly, the lubricity of the sliding surface <NUM> attributable to the sealing target liquid F is improved.

In addition, the sealing target liquid F that has flowed out from the positive pressure generation groove <NUM> to the land <NUM> as described above flows into another positive pressure generation groove <NUM> arranged side by side on the downstream side as compared with the positive pressure generation groove <NUM> as indicated by the arrow H3. As a result, the internal pressure of the positive pressure generation groove <NUM> can be stabilized.

Next, the negative pressure generation groove <NUM> during the relative rotation of the rotating seal ring <NUM> will be described. When the rotating seal ring <NUM> rotates with respect to the stationary seal ring <NUM>, negative dynamic pressure is generated in the negative pressure generation groove <NUM>. With the sealing target liquid F introduced into the atmosphere-side end portion 171a side of the negative pressure generation groove <NUM>, the flow of the sealing target liquid F introduced from the atmosphere-side end portion 171a of the negative pressure generation groove <NUM> toward the leading edge portion 9a is generated as indicated by an arrow H4. It should be noted that the positive pressure in the negative pressure generation groove <NUM> gradually increases from the atmosphere-side end portion 171a side, which is the upstream side, toward the downstream side and the atmosphere-side end portion 171a has a relatively negative pressure.

In other words, the pressure is highest in the vicinity of the leading edge portion 9a, the sliding surfaces <NUM> and <NUM> are separated from each other, and a liquid film of the sealing target liquid F is formed on the sealing target liquid side between the sliding surfaces <NUM> and <NUM> by the sealing target liquid F flowing out from the vicinity of the leading edge portion 9a between the sliding surfaces <NUM> and <NUM> therearound as indicated by an arrow H5. Then, the sealing target liquid F flowing out of the liquid film flows to the negative pressure generation groove <NUM> of another dynamic pressure generation mechanism <NUM> adjacent to the downstream side. In this manner, the sealing target liquid F once introduced from the opening portion 15a is circulated in the circumferential direction between the plurality of dynamic pressure generation mechanisms <NUM>, and thus the sealing target liquid F can be prevented from leaking to the atmospheric side.

In addition, as described above, the sealing target liquid F is circulated in the circumferential direction between the plurality of dynamic pressure generation mechanisms <NUM> during the relative rotation of the plurality of leading edge portions 9a disposed on the sine wave-shaped virtual curve C. As a result, a gas-liquid interface Y1 between an atmosphere A and the sealing target liquid F on the sliding surface <NUM> is formed in a substantially sine wave shape on the atmospheric side as compared with the virtual curve C and a liquid film forming region Y (indicated by linear hatching in <FIG>) is formed on the sealing target liquid side including the positive pressure generation groove <NUM> and a part of the negative pressure generation groove <NUM> (see <FIG>). It should be noted that the surrounding sealing target liquid F is suctioned in by the relative negative pressure being generated on the atmosphere-side end portion 171a side of the negative pressure generation groove <NUM> and thus the sealing target liquid F that is to leak out to the atmospheric side can be returned to the sealing target liquid F side, which is the outer diameter side. In addition, it is a matter of course that the position of the gas-liquid interface Y1 and the range of the liquid film forming region Y vary from the position illustrated in <FIG> depending on, for example, the rotation speed of the rotating seal ring <NUM> during the relative rotation and the pressure of the sealing target liquid F.

In addition, the sealing target liquid F that has flowed out from the negative pressure generation groove <NUM> to the land <NUM> as described above flows into another negative pressure generation groove <NUM> arranged side by side on the downstream side as compared with the negative pressure generation groove <NUM> as indicated by an arrow H6. As a result, the internal pressure of the negative pressure generation groove <NUM> can be stabilized.

The positive pressure generation groove <NUM> extends at an angle to the downstream side while facing the atmospheric side as described above, and the sliding surface is provided with the negative pressure generation groove <NUM> extending continuously from the atmosphere-side end portion 9b of the positive pressure generation groove <NUM> and at an angle to the upstream side while facing the atmospheric side. In this respect, during the relative rotation of the rotating seal ring <NUM>, the liquid film of the sealing target liquid F formed in the leading edge portion 9a is suctioned in by the negative pressure generation groove <NUM> with a relatively negative pressure, and thus it is possible to prevent the sealing target liquid F from leaking to the atmospheric side and improve the sealability of the stationary seal ring <NUM> and the rotating seal ring <NUM>.

In addition, the land <NUM> is provided on the leak side of the sliding surface <NUM> as compared with the negative pressure generation groove <NUM> so as to be continuous over the circumferential direction, that is, in an annular shape. As a result, the atmosphere-side end portion 171a of the negative pressure generation groove <NUM> is blocked by the land <NUM>, and thus it is possible to prevent the sealing target liquid F from leaking to the atmospheric side when the rotating seal ring <NUM> is stationary.

In addition, the land <NUM> on the atmospheric side as compared with the negative pressure generation groove <NUM> has a constant radial width over the circumferential direction. As a result, the radial position of the atmosphere-side end portion 171a of the negative pressure generation groove <NUM> is constant over the circumferential direction, and thus manufacturing is facilitated.

Next, a modification example of the present embodiment will be described. It should be noted that configurations identical to those of the above embodiment will not be described below so that redundancy can be avoided. As illustrated in <FIG>, in a first modification example, the sliding surface <NUM> of a stationary seal ring <NUM>' is provided with a plurality of reverse dynamic pressure generation mechanisms <NUM>', which have tip portions facing the side opposite to the dynamic pressure generation mechanisms <NUM>, as well as the dynamic pressure generation mechanisms <NUM> arranged side by side in the circumferential direction. The reverse dynamic pressure generation mechanism <NUM>' has a substantially identical structure in which the dynamic pressure generation mechanism <NUM> is inverted in the circumferential direction. The side that is open to and communicates with the sealing target liquid side as one of the two sides constituting the V shape of the reverse dynamic pressure generation mechanism <NUM>' corresponds to a reverse positive pressure generation groove <NUM>' inclined to the side opposite to the positive pressure generation groove <NUM> while facing the atmospheric side and linearly recessed. The other side recessed so as to be continuous with the reverse positive pressure generation groove <NUM>' corresponds to a reverse negative pressure generation groove <NUM>' inclined to the side opposite to the negative pressure generation groove <NUM> while facing the atmospheric side and linearly recessed to an atmosphere-side end portion 171a' blocked as the leak side. In addition, the tip portion where the two sides of the V shape intersect corresponds to a reverse leading edge portion 9a'.

In a case where the rotating seal ring <NUM> rotates in the counterclockwise direction of the page indicated by the solid-line arrow in <FIG>, that is, forward, the sealing target liquid F introduced from the opening portion 15a follows and moves to the downstream side in the positive pressure generation groove <NUM>. This leads to positive pressure generation and liquid film formation in the leading edge portion 9a. In the negative pressure generation groove <NUM>, the introduced sealing target liquid F follows and moves to the downstream side, leading to relative negative pressure generation on the atmosphere-side end portion 171a side. In addition, in a case where the rotating seal ring <NUM> rotates in the clockwise direction of the page indicated by the dotted-line arrow in <FIG>, that is, reversely, the sealing target liquid F introduced from an opening portion 15a' follows and moves to the downstream side in the reverse rotation occasion in the reverse positive pressure generation groove <NUM>'. This leads to positive pressure generation and liquid film formation in the reverse leading edge portion 9a'. In the reverse negative pressure generation groove <NUM>', the introduced sealing target liquid F follows and moves to the downstream side in the reverse rotation occasion, leading to relative negative pressure generation on the atmosphere-side end portion 171a' side. In other words, in a case where the rotating seal ring <NUM> rotates in the clockwise direction of the page of <FIG>, the reverse positive pressure generation groove <NUM>' functions as a positive pressure generation groove and the reverse negative pressure generation groove <NUM>' functions as a negative pressure generation groove.

As described above, the sliding surface <NUM> of the stationary seal ring <NUM>' includes the dynamic pressure generation mechanism <NUM> having a tip portion facing the downstream side in the relative rotation direction in the forward rotation occasion and the reverse dynamic pressure generation mechanism <NUM>' having a tip portion facing the downstream side in the relative rotation direction in the reverse rotation occasion. Accordingly, use is possible regardless of the direction in which the stationary seal ring <NUM> and the rotating seal ring <NUM> rotate relative to each other.

Next, a second modification example will be described. As illustrated in <FIG>, on the sliding surface <NUM> of a stationary seal ring <NUM>, the plurality of leading edge portions 9a arranged side by side and a plurality of bent portions 92c on the upstream side where a positive pressure generation groove <NUM> and a negative pressure generation groove <NUM> intersect have radial positions gradually changing along the circumferential direction and are disposed on the sine wave-shaped virtual curve C, and thus manufacturing is facilitated.

Next, the sliding component according to the third embodiment of the present invention will be described with reference to <FIG>. It should be noted that configurations identical to those of the second embodiment will not be described below so that redundancy can be avoided.

As illustrated in <FIG>, a plurality of dynamic pressure generation mechanisms <NUM> are evenly arranged in the circumferential direction on the sliding surface <NUM> of a stationary seal ring <NUM> and the dynamic pressure generation mechanism <NUM> includes the positive pressure generation groove <NUM> extending at an angle to the downstream side while facing the atmospheric side and a second positive pressure generation groove <NUM> independent of the positive pressure generation groove <NUM> and extending at an angle to the upstream side while facing the atmospheric side. It should be noted that the number of the second positive pressure generation grooves <NUM> is equal to the number of the positive pressure generation grooves <NUM> and the second positive pressure generation grooves <NUM> are disposed in a corresponding manner so as to be positioned on the same radius. However, the present invention is not limited thereto and the number or position may not correspond.

The positive pressure generation groove <NUM> is provided with the opening portion 15a open to and communicating with the sealing target liquid side and is linearly recessed to the blocked atmosphere-side end portion 9b. The leading edge portion 9a is disposed at the downstream-side leading edge of the atmosphere-side end portion 9b. In addition, the radial positions of the leading edge portions 9a of the plurality of positive pressure generation grooves <NUM> arranged side by side gradually change along the circumferential direction and the leading edge portions 9a are disposed on the smooth and continuous virtual curve C having a sine wave shape over the circumferential direction.

The second positive pressure generation groove <NUM> is provided with an opening portion 173a open to and communicating with the atmospheric side and is linearly recessed to a blocked sealing target liquid-side end portion 17b. The leading edge portion 9a is disposed at the downstream-side leading edge of the sealing target liquid-side end portion 17b. In addition, the radial width of the land <NUM> provided between the positive pressure generation groove <NUM> and the second positive pressure generation groove <NUM> in the radial direction is constant over the circumferential direction.

Next, the operation of the rotating seal ring <NUM> during the relative rotation will be described. It should be noted that the operation in the positive pressure generation groove <NUM> is similar to those of the first and second embodiments and thus redundant description will be omitted unless otherwise specified.

First, during the non-operation of a general industrial machine and non-rotation of the rotating seal ring <NUM>, capillarity causes the sealing target liquid F on the sealing target liquid side as compared with the sliding surfaces <NUM> and <NUM> to slightly enter between the sliding surfaces <NUM> and <NUM> and the dynamic pressure generation mechanism <NUM> is filled with the sealing target liquid F that has flowed in from the opening portion 15a of the positive pressure generation groove <NUM>. It should be noted that the sealing target liquid F is higher in viscosity than a gas and thus the amount of leakage from the dynamic pressure generation mechanism <NUM> to the atmospheric side is extremely small when the general industrial machine is stopped.

Next, when the rotating seal ring <NUM> rotates with respect to the stationary seal ring <NUM> as illustrated in <FIG> and <FIG>, the flow of the sealing target liquid F on the sealing target liquid side introduced from the opening portion 15a of the positive pressure generation groove <NUM> toward the leading edge portion 9a is generated as indicated by the arrow H1. Accordingly, dynamic pressure is generated in the positive pressure generation groove <NUM>. It should be noted that the positive pressure in the positive pressure generation groove <NUM> gradually increases from the opening portion 15a side, which is the upstream side, toward the leading edge portion 9a on the downstream side.

In addition, the sealing target liquid F that has flowed out from the positive pressure generation groove <NUM> to the land <NUM> as described above flows into another positive pressure generation groove <NUM> arranged side by side on the downstream side as compared with the positive pressure generation groove <NUM> as indicated by the arrow H3. As a result, a liquid film having a substantially uniform film thickness is formed in a liquid film forming region W (indicated by linear hatching in <FIG>).

Next, the second positive pressure generation groove <NUM> during the relative rotation of the rotating seal ring <NUM> will be described. As illustrated in <FIG>, when the rotating seal ring <NUM> rotates with respect to the stationary seal ring <NUM>, the flow of the atmospheric-side atmosphere A introduced from the opening portion 173a of the second positive pressure generation groove <NUM> toward a second leading edge portion 17a is generated as indicated by an arrow L1, and thus dynamic pressure is generated in the second positive pressure generation groove <NUM>. It should be noted that the positive pressure in the second positive pressure generation groove <NUM> gradually increases from the opening portion 173a side, which is the upstream side, toward the second leading edge portion 17a on the downstream side.

In other words, the pressure is highest in the vicinity of the second leading edge portion 17a positioned at the downstream-side leading edge of the second positive pressure generation groove <NUM>, the sliding surfaces <NUM> and <NUM> are separated from each other, and the atmosphere A flows out from the vicinity of the second leading edge portion 17a between the sliding surfaces <NUM> and <NUM> therearound as indicated by an arrow L2. As a result of this positive pressure generation in the vicinity of the second leading edge portion 17a, it is possible to repel the sealing target liquid F approaching the vicinity of the second leading edge portion from the sealing target liquid side and prevent the sealing target liquid F from leaking to the atmospheric side.

In addition, a liquid film is formed during the relative rotation of the rotating seal ring <NUM> in the plurality of leading edge portions 9a disposed on the sine wave-shaped virtual curve C as described above and the liquid film is not allowed to enter the atmospheric side by the positive pressure generated by the atmosphere A concentrating on a plurality of the second leading edge portions 17a during the relative rotation of the rotating seal ring <NUM>. Accordingly, a gas-liquid interface W1 between the atmosphere A and the sealing target liquid F on the sliding surface <NUM> is formed in a sine wave shape between a plurality of the atmosphere-side end portions 9b and a plurality of the sealing target liquid-side end portions 17b and the liquid film forming region W is formed on the sealing target liquid side including the positive pressure generation groove <NUM> (see <FIG>). In addition, it is a matter of course that the position of the gas-liquid interface W1 and the range of the liquid film forming region W vary from the position illustrated in <FIG> depending on, for example, the rotation speed of the rotating seal ring <NUM> during the relative rotation and the pressure of the sealing target liquid F.

A case where the sealing target liquid F does not enter the land <NUM> on the atmospheric side during the relative rotation of the rotating seal ring <NUM> will be described first. A part of the atmosphere A in the second positive pressure generation groove <NUM> follows the relative rotation of the rotating seal ring <NUM> and flows out to the land <NUM> on the downstream side with its pressure increased. As a result, the gas-liquid interface W1 is maintained between the positive pressure generation groove <NUM> and the second positive pressure generation groove <NUM> illustrated in <FIG> and the sealing target liquid F to enter the second positive pressure generation groove <NUM> side is blocked.

Next, a case where the sealing target liquid F has entered the land <NUM> on the atmospheric side during the relative rotation of the rotating seal ring <NUM> will be described. As illustrated in <FIG>, the atmosphere A on the atmospheric side is introduced from the opening portion 173a of the second positive pressure generation groove <NUM> toward the second leading edge portion 17a as indicated by an arrow L3. In addition, the sealing target liquid F is introduced from the land <NUM> as indicated by an arrow H9 and merges with the flow of the atmosphere A indicated by the arrow L3, the flow of the sealing target liquid F toward the second leading edge portion 17a indicated by an arrow H7 is generated, and dynamic pressure is generated in the second positive pressure generation groove <NUM>. It should be noted that the positive pressure in the second positive pressure generation groove <NUM> gradually increases from the opening portion 173a side, which is the upstream side, toward the second leading edge portion 17a on the downstream side as in the case of <FIG>.

In other words, the pressure is highest in the vicinity of the second leading edge portion 17a positioned at the downstream-side leading edge of the second positive pressure generation groove <NUM> and the sealing target liquid F flows out from the vicinity of the second leading edge portion 17a between the sliding surfaces <NUM> and <NUM> therearound as indicated by an arrow H8. In this manner, it is possible to return the sealing target liquid F that has entered the land <NUM> to the sealing target liquid side, which is the outer diameter side, and prevent the sealing target liquid F from leaking to the atmospheric side. It should be noted that the sealing target liquid F is incompressible and high in viscosity as compared with the atmosphere and thus the sealing target liquid F that has entered the second positive pressure generation groove <NUM> easily flows out between the sliding surfaces <NUM> and <NUM> as the rotating seal ring <NUM> is relatively rotated.

As described above, the second positive pressure generation groove <NUM> is provided that is independent of the positive pressure generation groove <NUM> on the atmospheric side as compared with the positive pressure generation groove <NUM> and generates positive pressure by the atmosphere on the atmospheric side as compared with the positive pressure generation groove <NUM> being introduced during the relative rotation of the rotating seal ring <NUM>. The second positive pressure generation groove <NUM> is provided with the second leading edge portion 17a at the leading edge on the downstream side in the relative rotation direction. In this respect, during the relative rotation of the rotating seal ring <NUM>, the atmosphere on the atmospheric side flows to the downstream side of the second positive pressure generation groove <NUM> and concentrates on the second leading edge portion 17a to lead to positive pressure generation, and thus it is possible to repel the sealing target liquid F approaching the vicinity of the second leading edge portion 17a from the sealing target liquid side and prevent the sealing target liquid F from leaking to the atmospheric side.

In addition, since the second positive pressure generation grooves <NUM> are disposed so as to correspond in number and position to the positive pressure generation grooves <NUM>, the second positive pressure generation grooves <NUM> can be machined in accordance with the number and positions of the positive pressure generation grooves <NUM> and are easy to manufacture.

In addition, since <NUM> is provided in an annular shape between the positive pressure generation groove <NUM> and the second positive pressure generation groove <NUM> in the radial direction, the positive pressure generation groove <NUM> and the second positive pressure generation groove <NUM> can be separated from each other and the functions of both during the relative rotation can be clarified.

In addition, since the radial width of the land <NUM> provided between the positive pressure generation groove <NUM> and the second positive pressure generation groove <NUM> in the radial direction is constant over the circumferential direction, the second leading edge portion 17a is separated from the leading edge portion 9a to the leak side by a constant dimension. The second leading edge portion 17a where positive pressure is generated during the relative rotation is disposed at positions with different diameter lengths in the circumferential direction, and thus it is possible to prevent the sealing target liquid F flowing from the liquid film generated in the leading edge portion 9a during the relative rotation from entering the atmospheric side.

Next, a modification example will be described. It should be noted that configurations identical to those of the above embodiment will not be described below so that redundancy can be avoided. As illustrated in <FIG>, on the sliding surface <NUM> of a stationary seal ring <NUM> in a third modification example, the plurality of leading edge portions 9a arranged side by side and the corner portion 9c positioned on the upstream side of the atmosphere-side end portion 9b of a positive pressure generation groove <NUM> have radial positions gradually changing along the circumferential direction and are disposed on the sine wave-shaped virtual curve C, and thus manufacturing is facilitated.

Although embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to the embodiments.

For example, although the mechanical seal for general industrial machine has been described as an example of the sliding component in the above embodiments, the mechanical seal may be replaced with another mechanical seal for an automobile, a water pump, or the like. In addition, the present invention is not limited to the mechanical seal and may be a sliding component other than a mechanical seal, examples of which include a slide bearing.

In addition, although an example in which the dynamic pressure generation mechanism is provided only on the stationary seal ring <NUM> has been described in the above embodiment, the dynamic pressure generation mechanism may be provided only on the rotating seal ring <NUM> or on both the stationary and rotating seal rings.

In addition, although the leading edge portion 9a and the corner portion 9c or the bent portion 92c are disposed on the smooth, continuous, and sine wave-shaped virtual curve C in the above embodiment, the present invention is not limited thereto. For example, the virtual curve may be wavy with a small period or have a rectangular wave shape.

In addition, although the positive pressure generation groove <NUM>, the negative pressure generation groove, the reverse positive pressure generation groove <NUM>', the reverse negative pressure generation groove <NUM>', and the second positive pressure generation groove <NUM> are linearly recessed in the above embodiments, the present invention is not limited thereto. For example, the positive pressure generation groove <NUM>, the negative pressure generation groove, the reverse positive pressure generation groove <NUM>', the reverse negative pressure generation groove <NUM>', and the second positive pressure generation groove <NUM> may be recessed in a curved shape.

In addition, although the positive pressure generation groove is provided with the opening portion 15a open to and communicating with the sealing target liquid side in the above description, the present invention is not limited thereto and the positive pressure generation groove may be blocked without opening.

Claim 1:
Sliding components (<NUM>, <NUM>) for a shaft sealing device shaft-sealing a rotary shaft (<NUM>) of a rotating machine, wherein the sliding components (<NUM>, <NUM>) are in number of two that are a stationary seal ring and a rotating seal ring and are configured to rotate relative to each other and formed in an annular shape and disposed at a relative rotation point of the rotating machine, comprising a plurality of first positive pressure generation grooves (<NUM>) arranged side by side in a circumferential direction on a sliding surface (<NUM>, <NUM>) of the sliding components (<NUM>, <NUM>),
the plurality of first positive pressure generation grooves (<NUM>) being configured for generating positive pressure by a sealing target fluid on a sealing target fluid side which is introduced during the relative rotation of the sliding components (<NUM>, <NUM>),
the first positive pressure generation grooves (<NUM>) having a plurality of leading edge portions (9a) at leading edges on a downstream side in a direction of the relative rotation,
the plurality of leading edge portions (9a) being arranged side by side in the circumferential direction,
at least part of the plurality of leading edge portions (9a) being disposed at different radial positions, characterized in that
each of the plurality of first positive pressure generation grooves (<NUM>) extends at an angle to the downstream side in the relative rotation direction while facing a leak side, and
the sliding surface (<NUM>, <NUM>) is provided with a negative pressure generation groove (<NUM>) extending so as to be continuous from a leak-side end portion (9b) of each of the plurality of first positive pressure generation grooves (<NUM>) and at an angle to an upstream side in the relative rotation direction while facing the leak side.