JP2014185691A - Mechanical seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanical seal capable of improving corrosion resistance, wear resistance and workability in a lump.SOLUTION: A mechanical seal 1 prevents the leakage of a fluid R from between a housing 3 having an opening 6 through which a rotating shaft 4 is inserted and the rotating shaft 4 through the opening 6. The mechanical seal 1 includes a fixed ring 11 fixed to the housing 3 at the opening 6 and externally fitted to the rotating shaft 4, and a rotary ring 12 externally fitted to the rotating shaft 4 in an integrally rotatable manner. With the rotation of the rotating shaft 4, a rotation side seal face 37 of the rotary ring 12 comes in slide contact with a fixed side seal face 17 of the fixed ring 11. On at least one of the rotation side seal face 37 and the fixed side seal face 17, a DLC film 14 is provided which contains silicon of more than 0 wt.% and 30 wt.% or less.

Description

  The present invention relates to a mechanical seal.

  The mechanical seal proposed in the following Patent Document 1 includes a seat ring fitted in a machine main body (a cover, a casing, or the like), a driven ring, and the like. The seat ring and the driven ring are fitted on the rotation shaft, and the driven ring rotates integrally with the rotation shaft. End surfaces facing each other in the seat ring and the driven ring come into sliding contact with each other as the rotating shaft rotates. This prevents the fluid from leaking along the end surfaces of the seat ring and the driven ring.

  As a material for such a mechanical seal, Patent Document 2 discloses using an SiC-based sliding material having excellent corrosion resistance, wear resistance, and the like.

Japanese Utility Model Publication No. 63-106963 JP-A-4-272996

Ceramic that is a material for the SiC-based sliding material has poor workability and high material cost. Therefore, when used as a material for a mechanical seal, it is inevitable that processing takes time and cost.
The present invention has been made under such a background, and an object thereof is to provide a mechanical seal capable of improving corrosion resistance, wear resistance, and workability at a time.

  According to the first aspect of the present invention, leakage of the fluid (R) at the opening between the housing (3) in which the opening (6) through which the rotating shaft (4) is inserted and the rotating shaft is formed. A mechanical seal (1) for blocking, which is fixed to the housing at the opening, and is fixed to the housing and externally fitted to the rotating shaft, and is integrally rotatable with respect to the rotating shaft A rotary ring (12) to be externally fitted, a fixed seal surface (17) provided on the fixed ring and facing the rotary ring in the axial direction (X) of the rotary shaft, and provided on the rotary ring, A rotation-side seal surface (37) facing the fixed-side seal surface in the axial direction and slidingly contacting the fixed-side seal surface as the rotation shaft rotates; the rotation-side seal surface and the fixed-side seal surface; Urging member (13) for moving the Provided on at least one of the sealing surface and the stationary sealing surface, characterized in that it comprises a DLC film (14) containing a number 30 wt% or less of silicon than 0 wt%, and a mechanical seal.

  According to a second aspect of the present invention, the rotating ring has the rotation-side sealing surface and is movable in the axial direction with respect to the first rotating ring and the first rotating ring in the axial direction. A second rotating ring (32) disposed on the opposite side of the fixed ring and movable in the axial direction, wherein the biasing member attaches the second rotating ring toward the first rotating ring. A depression (38) facing the second rotation ring side is formed on the inner peripheral surface of the first rotation ring, and the second rotation ring is inserted into the depression (46). The DLC film is provided on at least one of the inner peripheral surface (35A) of the first rotating ring in the recess and the surface (41B) facing the inner peripheral surface in the insertion portion. The mechanical seal according to claim 1, wherein:

According to a third aspect of the present invention, the rotating ring is disposed on the opposite side of the fixed ring with respect to the second rotating ring in the axial direction, and has a third rotating ring (33) positioned in the axial direction. The mechanical seal according to claim 2, wherein the biasing member is interposed between the second rotating ring and the third rotating ring.
The invention according to claim 4 is characterized in that the DLC film is provided in a portion in contact with the fluid in each of the stationary ring and the rotating ring. It is a mechanical seal.

The invention according to claim 5 is the mechanical seal according to any one of claims 1 to 4, wherein the stationary ring and the rotating ring are made of general-purpose steel.
In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

According to the first aspect of the present invention, in the mechanical seal, the fixed-side seal surface of the fixed ring and the rotary-side seal surface of the rotating ring are in sliding contact with the rotation of the rotating shaft. Can be prevented from leaking between the fixed-side seal surface and the rotary-side seal surface.
Here, since a DLC film (amorphous carbon coating) excellent in corrosion resistance and wear resistance is provided on at least one of the rotation side seal surface and the fixed side seal surface, the rotation side seal surface and the fixed side seal surface Corrosion and wear on the sealing surface can be suppressed. Since this DLC film is a special DLC film containing silicon (Si) that is greater than 0 wt% and less than or equal to 30 wt%, the friction coefficient is particularly low in a liquid, and high wear resistance can be exhibited.

In addition, when a DLC film is provided on the rotating side sealing surface or the fixing side sealing surface after forming the stationary ring and the rotating ring with a material having good workability (for example, the general-purpose steel according to claim 5), SiC or the like Compared with the case where the mechanical seal is formed of ceramic, the workability of the entire mechanical seal is better.
As described above, in the mechanical seal, it is possible to improve corrosion resistance, wear resistance, and workability at a time.

According to invention of Claim 2, the inner peripheral surface in the hollow of a 1st rotation ring and the surface of the insertion part of a 2nd rotation ring are the movement to the axial direction of a 1st rotation ring or a 2nd rotation ring. In some cases, sliding contact may occur. Therefore, if the DLC film is provided on the inner peripheral surface and the surface, the corrosion resistance and wear resistance on the inner peripheral surface and the surface can be improved.
According to the third aspect of the present invention, the biasing member that brings the rotation-side seal surface and the stationary-side seal surface closer to each other is interposed between the second rotation ring and the third rotation ring and compressed. Thereby, since the urging member presses the second rotating ring against the first rotating ring, the rotating side seal surface of the first rotating ring can be brought close to the fixed side seal surface of the fixed ring.

  According to the fourth aspect of the present invention, if a DLC film having good corrosion resistance is provided in a portion in contact with a fluid in each of the stationary ring and the rotating ring, corrosion in the portion can be suppressed.

FIG. 1 is a schematic sectional view of an apparatus 2 to which a mechanical seal 1 according to an embodiment of the present invention is applied. FIG. 2 is an enlarged view of a main part of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic sectional view of an apparatus 2 to which a mechanical seal 1 according to an embodiment of the present invention is applied. FIG. 2 is an enlarged view of a main part of FIG. In the following description, reference numerals that do not appear in FIG. 1 are shown in FIG.
With reference to FIGS. 1 and 2 (see FIG. 2 for details), the device 2 is, for example, a submersible pump. The device 2 includes a housing 3 that forms an outer shell thereof, and a rotating shaft 4 that is rotatably supported by the housing 3.

The housing 3 is a hollow body made of metal, for example. The hollow portion 5 of the housing 3 contains a fluid R (here, a liquid such as water). The fluid R existing in the hollow portion 5 is indicated by thin dots in FIGS. 1 and 2.
The housing 3 is formed with a round opening 6 that allows the hollow portion 5 to communicate with the outside of the housing 3. The opening 6 passes through the wall 3A that defines the hollow portion 5 in the housing 3 in the thickness direction of the wall 3A (the left-right direction in FIGS. 1 and 2).

  A circumferential surface that borders the opening 6 in the housing 3 (hereinafter referred to as “inner circumferential surface 7”) is reduced in diameter in a stepped manner as it approaches the outside of the housing 3 from the hollow portion 5. The inner peripheral surface 7 includes a first inner peripheral surface 7A, a second inner peripheral surface 7B having a diameter smaller than that of the first inner peripheral surface 7A, and a third inner diameter having a diameter smaller than that of the second inner peripheral surface 7B. 7C of peripheral surfaces. The inner peripheral surface 7 is connected to the first connecting surface 7D that connects the first inner peripheral surface 7A and the second inner peripheral surface 7B, and the second connection that connects the second inner peripheral surface 7B and the third inner peripheral surface 7C. Surface 7E. The first connection surface 7D and the second connection surface 7E are flat along the radial direction of the inner peripheral surface 7, and have an annular shape when viewed from the thickness direction described above.

  The rotating shaft 4 is a cylindrical body extending in the thickness direction described above. The direction in which the rotating shaft 4 extends (the thickness direction described above) will be referred to as the axial direction X of the rotating shaft 4. The rotating shaft 4 is inserted coaxially with the first portion 8 disposed in the hollow portion 5 of the housing 3 and the opening 6 of the housing 3 (at the same position as the opening 6 in the axial direction X). ) The second portion 9 and the third portion 10 disposed outside the housing 3 are integrally included. The outer diameter of the outer peripheral surface 4 </ b> A of the rotating shaft 4 is the same in the second portion 9 and the portion adjacent to the second portion 9 in each of the first portion 8 and the third portion 10. Therefore, the second portion 9 and the portion adjacent to the second portion 9 in each of the first portion 8 and the third portion 10 are not formed with a step on the outer peripheral surface 4 </ b> A of the rotating shaft 4. The outer diameter (diameter) is smaller than the inner diameter (diameter) of the third inner peripheral surface 7C in the opening 6. Therefore, the second portion 9 inserted through the opening 6 is on the inner side in the radial direction (the radial direction of the rotary shaft 4 and the opening 6) with respect to the inner peripheral surface 7 of the opening 6. 7 is not touching.

A bearing (not shown) is fixed to the housing 3, and the housing 3 rotatably supports the rotating shaft 4 via the bearing. The rotating shaft 4 is rotatable about its central axis J.
The device 2 has a drive mechanism (not shown) such as an electric motor, and the rotating shaft 4 is connected to the drive mechanism. Therefore, when the driving mechanism generates a driving force, the rotating shaft 4 rotates by receiving this driving force.

  In the device 2, the fluid R existing in the hollow portion 5 of the housing 3 leaks from the space between the inner peripheral surface 7 of the opening 6 and the outer peripheral surface 4 </ b> A of the rotating shaft 4 in the second portion 9 to the outside of the housing 3. There is a need to stop. Therefore, the above-described mechanical seal 1 is provided in the device 2 to prevent leakage of the fluid R at the opening 6 between the housing 3 and the rotating shaft 4 and is disposed in the hollow portion 5. Yes.

The mechanical seal 1 includes a stationary ring 11, a rotating ring 12, a biasing member 13, and a DLC film 14. In the following, each member will be described with reference to the postures of FIGS. 1 and 2.
The fixed ring 11 is a ring (ring) that is coaxially fitted to the rotating shaft 4. Therefore, the direction in which the central axis of the fixed ring 11 extends coincides with the axial direction X. The fixed ring 11 includes an outer peripheral surface 15, an inner peripheral surface 16, a fixed-side seal surface 17 that is an end surface on one side in the axial direction X (left side in FIGS. 1 and 2), and the other side in the axial direction X (see FIG. 1 and a positioning surface 18 which is an end surface on the right side in FIG.

  The outer peripheral surface 15 includes a first outer peripheral surface 15A on the fixed seal surface 17 side, a second outer peripheral surface 15B on the positioning surface 18 side, and a connection surface 15C that forms a boundary between the first outer peripheral surface 15A and the second outer peripheral surface 15B. Is included. The first outer peripheral surface 15 </ b> A has substantially the same diameter as the first inner peripheral surface 7 </ b> A in the opening 6 of the housing 3. The second outer peripheral surface 15B has substantially the same diameter as the second inner peripheral surface 7B in the opening 6 and is smaller in diameter than the first outer peripheral surface 15A. The connection surface 15 </ b> C is flat along the radial direction of the stationary ring 11 (the direction orthogonal to the axial direction X) and is annular when viewed from the axial direction X.

The inner peripheral surface 16 has a slightly larger diameter than the outer peripheral surface 4A of the rotating shaft 4.
The fixed-side seal surface 17 is flat along the radial direction of the fixed ring 11 and has an annular shape when viewed from the axial direction X. In this embodiment, the conical tapered surface 19 inclined with respect to the axial direction X includes the outer peripheral edge of the fixed-side seal surface 17 and the end of the outer peripheral surface 15 (first outer peripheral surface 15A) on the fixed-side seal surface 17 side. Relay with the edge. The tapered surface 19 may be omitted and the outer peripheral edge of the fixed-side seal surface 17 and the edge of the outer peripheral surface 15 may be directly connected.

The positioning surface 18 is flat along the radial direction of the stationary ring 11 and has an annular shape when viewed from the axial direction X.
In the stationary ring 11 that is externally fitted to the rotating shaft 4, a portion on the second outer peripheral surface 15 </ b> B side is press-fitted into the opening 6 of the housing 3. Thereby, the stationary ring 11 is coaxial with the opening 6 and is fixed to the housing 3 at the opening 6. In this state, in the fixed ring 11, the first outer peripheral surface 15 </ b> A is in surface contact with the first inner peripheral surface 7 </ b> A of the opening 6 over the entire circumference from the radially inner side. The second outer peripheral surface 15B is in surface contact with the second inner peripheral surface 7B of the opening 6 from the radially inner side over the entire circumference. In the stationary ring 11, the positioning surface 18 is in surface contact with the second connection surface 7 </ b> E of the opening 6 over the entire circumference from the hollow portion 5 side in the axial direction X. The connection surface 15C is opposed to the first connection surface 7D with a gap from the hollow portion 5 side in the axial direction X.

  Here, at the boundary between the second outer peripheral surface 15B and the connection surface 15C on the outer peripheral surface 15 of the fixed ring 11, a seal member 20 formed of a ring such as rubber is externally fitted as a so-called secondary seal. The seal member 20 of this embodiment is an O-ring. The seal member 20 is disposed in an annular space 21 defined by the connection surface 15C, the first connection surface 7D, the first inner peripheral surface 7A, and the second outer peripheral surface 15B, and the connection surface 15C and the first connection surface 7D are separated from each other. Compressed between. Thereby, since the annular space 21 is sealed over the entire circumferential direction, the fluid R in the hollow portion 5 is between the outer peripheral surface 15 of the stationary ring 11 and the inner peripheral surface 7 of the opening 6 of the housing 3. Accordingly, leakage to the outside of the housing 3 is prevented.

  Further, the inner peripheral surface 16 of the fixed ring 11 is not in contact with the outer peripheral surface 4A of the rotating shaft 4 (specifically, the second portion 9 and its periphery). Therefore, the fixed ring 11 does not become a resistance to rotation of the rotating shaft 4. In the fixed ring 11, the fixed-side seal surface 17, the tapered surface 19, and the first outer peripheral surface 15 </ b> A on the tapered surface 19 side are exposed in the hollow portion 5 and are in contact with the fluid R.

The rotary ring 12 is a ring (ring) that is coaxially fitted to the rotary shaft 4. Therefore, the direction in which the central axis of the rotating ring 12 extends coincides with the axial direction X. The entire rotating ring 12 is disposed in the hollow portion 5 in the vicinity of the opening 6.
The rotating ring 12 includes a first rotating ring 31, a second rotating ring 32, and a third rotating ring 33. The first rotating ring 31, the second rotating ring 32, and the third rotating ring 33 are separate annular components, and are arranged coaxially. From the side closer to the fixed ring 11, in this order in the axial direction X Are lined up. That is, the second rotating ring 32 is disposed on the opposite side of the fixed ring 11 with respect to the first rotating ring 31 in the axial direction X. The third rotary ring 33 is disposed on the opposite side of the fixed ring 11 with respect to the second rotary ring 32 in the axial direction X.

The first rotating ring 31 includes an outer peripheral surface 34, an inner peripheral surface 35, a positioning surface 36 which is an end surface on one side in the axial direction X (left side in FIGS. 1 and 2), and the other side in the axial direction X (see FIG. 1 and the rotation side sealing surface 37 which is an end surface on the right side in FIG.
The outer peripheral surface 34 has substantially the same diameter as the first outer peripheral surface 15A of the stationary ring 11.
The inner peripheral surface 35 is a boundary between the first inner peripheral surface 35A on the positioning surface 36 side, the second inner peripheral surface 35B on the rotation side seal surface 37 side, and the first inner peripheral surface 35A and the second inner peripheral surface 35B. And a connecting surface 35C formed. The first inner peripheral surface 35 </ b> A has a larger diameter than the outer peripheral surface 4 </ b> A of the rotating shaft 4. The second inner peripheral surface 35B has substantially the same diameter as the outer peripheral surface 4A and is smaller in diameter than the first inner peripheral surface 35A. The connection surface 35 </ b> C is flat along the radial direction of the first rotating ring 31 (direction orthogonal to the axial direction X) and is annular when viewed from the axial direction X. The inner peripheral surface 35 is formed with a recess 38 defined by the first inner peripheral surface 35A and the connection surface 35C. The recess 38 is a donut-shaped space that is coaxial with the first rotary ring 31 and is recessed from the positioning surface 36 toward the rotation-side seal surface 37.

  The positioning surface 36 is flat along the radial direction of the first rotary ring 31, and has an annular shape when viewed from the axial direction X. The inner peripheral edge of the positioning surface 36 is connected to the first inner peripheral surface 35A. The recess 38 is exposed from the positioning surface 36 and faces the second rotary ring 32 side (left side in FIGS. 1 and 2) from the axial direction X. Cutouts 39 extending in the radial direction of the first rotating ring 31 are formed at a plurality of locations on the circumference of the positioning surface 36 (see FIG. 1). Each notch 39 extends along the axial direction X toward the rotation-side seal surface 37 and penetrates the peripheral wall of the first rotation ring 31 and is exposed to both the outer peripheral surface 34 and the first inner peripheral surface 35A. ing. An end portion of the notch 39 on the rotation side seal surface 37 side is rounded so as to bulge toward the rotation side seal surface 37 side.

  The rotation-side sealing surface 37 is flat along the radial direction of the first rotation ring 31 and has an annular shape when viewed from the axial direction X. In this embodiment, a conical tapered surface 40 inclined with respect to the axial direction X relays the outer peripheral edge of the rotation-side seal surface 37 and the edge of the outer peripheral surface 34 on the rotation-side seal surface 37 side. . The tapered surface 40 may be omitted, and the outer peripheral edge of the rotation-side seal surface 37 and the outer peripheral surface 34 may be directly connected.

  In the first rotating ring 31 that is externally fitted to the rotating shaft 4, the rotating-side seal surface 37 faces the fixed-side seal surface 17 of the fixed ring 11 in the axial direction X over the entire circumferential direction. Between the second inner peripheral surface 35B and the outer peripheral surface 4A of the rotating shaft 4 (specifically, the first portion 8), there is a minute gap over the entire periphery. Therefore, the first rotating ring 31 can move relative to the rotating shaft 4 along the axial direction X.

The second rotating ring 32 includes an outer peripheral surface 41, an inner peripheral surface 42, a first end surface 43 which is an end surface on one side in the axial direction X (left side in FIGS. 1 and 2), and the other side in the axial direction X ( 2 and the second end face 44 which is the end face on the right side in FIGS. 1 and 2.
The outer peripheral surface 41 includes a first outer peripheral surface 41A on the first end surface 43 side, a second outer peripheral surface 41B on the second end surface 44 side, and a connection surface 41C that forms a boundary between the first outer peripheral surface 41A and the second outer peripheral surface 41B. Is included. The first outer peripheral surface 41 </ b> A has substantially the same diameter as the outer peripheral surface 34 of the first rotating ring 31. The second outer peripheral surface 41B has substantially the same diameter as the first inner peripheral surface 35A of the first rotating ring 31 and a smaller diameter than the first outer peripheral surface 41A. A plurality of elongated columnar protrusions 45 projecting outward in the radial direction of the second rotating ring 32 (a direction orthogonal to the axial direction X) are provided at a plurality of locations on the circumference of the second outer peripheral surface 41B (see FIG. (See FIG. 1). The protrusions 45 are provided in the same number as the notches 39 of the first rotating ring 31. The connection surface 41 </ b> C is flat along the radial direction of the second rotary ring 32 and has an annular shape when viewed from the axial direction X.

The inner circumferential surface 42 has substantially the same diameter as each of the second inner circumferential surface 35B of the first rotating ring 31 and the outer circumferential surface 4A of the rotating shaft 4.
The first end face 43 is flat along the radial direction of the second rotary ring 32 and has an annular shape when viewed from the axial direction X. The first end face 43 is provided with a guide bar 48 that protrudes along the axial direction X (see FIG. 1). The guide bar 48 may be provided at one place on the circumference of the first end face 43 or may be provided at a plurality of places spaced in the circumferential direction.

The second end face 44 is flat along the radial direction of the second rotary ring 32 and has an annular shape when viewed from the axial direction X. The outer peripheral edge of the second end surface 44 is connected to the second outer peripheral surface 41B.
In the second rotating ring 32, a portion in a range that coincides with the second outer peripheral surface 41 </ b> B in the axial direction X constitutes an annular insertion portion 46. The outer peripheral surface of the insertion portion 46 is the second outer peripheral surface 41B, the inner peripheral surface of the insertion portion 46 is the inner peripheral surface 42 on the second outer peripheral surface 41B side, and the second end surface 44 is the axis of the insertion portion 46. It is an end surface on the first rotating ring 31 side in the direction X.

  In the second rotating ring 32 that is externally fitted to the rotating shaft 4, the insertion portion 46 extends from the side opposite to the stationary ring 11 (the left side in FIGS. 1 and 2) from the opposite side to the first rotating ring. 31 is inserted into the recess 38. Thereby, the second rotary ring 32 is arranged coaxially with the first rotary ring 31. In the second rotating ring 32, the second outer peripheral surface 41 </ b> B is in surface contact with the first inner peripheral surface 35 </ b> A of the first rotating ring 31 from the radially inner side to the entire periphery. In the second rotating ring 32, the connection surface 41 </ b> C faces the positioning surface 36 of the first rotating ring 31 with a gap from the opposite side in the axial direction X. Further, the second end surface 44 faces the connection surface 35 </ b> C on the inner peripheral surface 35 of the first rotating ring 31 in the axial direction X with a gap from the opposite side. Between the inner peripheral surface 42 of the second rotating ring 32 and the outer peripheral surface 4A of the rotating shaft 4, there is a minute gap over the entire circumference. Therefore, the second rotating ring 32 can move relative to the rotating shaft 4 along the axial direction X.

  Here, the protrusions 45 of the second rotating ring 32 are fitted into the notches 39 of the first rotating ring 31 one by one from the opposite side (see FIG. 1). Thereby, the second rotating ring 32 is positioned in the circumferential direction with respect to the first rotating ring 31. Further, the second rotating ring 32 can move relative to the first rotating ring 31 in the axial direction X within a range in which each protrusion 45 can move in the axial direction X within the notch 39. When the second rotating ring 32 moves in the axial direction X with respect to the first rotating ring 31, the second outer peripheral surface 41 </ b> B of the second rotating ring 32 is in sliding contact with the first inner peripheral surface 35 </ b> A of the first rotating ring 31. . When the projection 45 reaches the end of the notch 39 (on the rotation side seal surface 37 side), the connection surface 41C of the second rotation ring 32 may contact the positioning surface 36 of the first rotation ring 31 ( (See FIG. 1).

Then, the rotation shaft 4 extends along the circumferential direction by the first inner circumferential surface 35A and the connection surface 35C of the first rotation ring 31, the second end surface 44 of the second rotation ring 32, and the outer circumferential surface 4A of the rotation shaft 4. An annular space 47 is defined.
In the annular space 47, a seal member 60 formed of a ring such as rubber is arranged as a so-called secondary seal. The seal member 60 of this embodiment is an O-ring and is externally fitted to the rotating shaft 4. The seal member 60 is compressed between the connection surface 35 </ b> C and the second end surface 44 in the annular space 47. Thereby, the annular space 47 is sealed over the entire circumferential direction. Therefore, the fluid R in the hollow portion 5 is located between the positioning surface 36 of the first rotating ring 31 and the connection surface 41C of the second rotating ring 32, and between the first inner peripheral surface 35A of the first rotating ring 31 and the second rotating ring. 32 and the second outer peripheral surface 41B of the first rotating ring 31 and the outer peripheral surface 4A of the rotating shaft 4 are prevented from leaking through the annular space 47 in order. ing. Further, the fluid R in the hollow portion 5 passes through the annular space 47 between the inner peripheral surface 42 of the second rotary ring 32 and the outer peripheral surface 4A of the rotary shaft 4 from the first end face 43 side of the second rotary ring 32. It is also prevented from leaking between the second inner peripheral surface 35B of the first rotating ring 31 and the outer peripheral surface 4A of the rotating shaft 4 in order. That is, the fluid R enters the space between the second inner peripheral surface 35B of the first rotating ring 31 and the outer peripheral surface 4A of the rotating shaft 4 beyond the annular space 47, and the inner peripheral surface 16 of the stationary ring 11 and the rotating shaft. The sealing member 60 prevents leakage from between the outer peripheral surface 4 </ b> A and the outside of the housing 3.

The third rotating ring 33 includes an outer peripheral surface 49, an inner peripheral surface 50, a first end surface 51 that is an end surface on one side in the axial direction X (left side in FIGS. 1 and 2), and the other side in the axial direction X ( 2 and the second end face 52 which is the end face on the right side in FIGS. 1 and 2.
The outer peripheral surface 49 has substantially the same diameter as the first outer peripheral surface 41 </ b> A of the second rotating ring 32. The inner peripheral surface 50 has substantially the same diameter as the outer peripheral surface 4A of the rotating shaft 4.

  Each of the first end surface 51 and the second end surface 52 is flat along the radial direction (direction orthogonal to the axial direction X) of the third rotating ring 33 and is annular when viewed from the axial direction X. . Concave portions 53 that are recessed in a cylindrical shape are formed at a plurality of locations on the circumference of the second end surface 52. The recesses 53 are arranged at equal intervals in the circumferential direction of the second end surface 52. The recess 53 extends along the axial direction X toward the first end face 51. The third rotating ring 33 includes a cylindrical surface 54 and a bottom surface 55 that define the recess 53. The bottom surface 55 forms the bottom of the recess 53 on the first end surface 51 side. The second end face 52 is formed with a guide hole 56 extending toward the first end face 51 (see FIG. 1). When a plurality of guide bars 48 are provided in the second rotating ring 32, the same number of guide holes 56 as the guide bars 48 are formed.

  The third rotary ring 33 is fitted on the rotary shaft 4 in a coaxial and press-fitted state. Therefore, in the third rotating ring 33, the entire inner peripheral surface 50 is pressed against the outer peripheral surface 4 </ b> A of the rotating shaft 4 from the outside in the radial direction. Therefore, unlike the first rotating ring 31 and the second rotating ring 32, the third rotating ring 33 cannot be moved relative to the rotating shaft 4 in the axial direction X, and is positioned with respect to the rotating shaft 4. . In addition to using press-fitting, the third rotating ring 33 may be fixed to the rotating shaft 4 with a screw or the like.

  In the third rotating ring 33, the second end face 52 is opposite to the fixed ring 11 side with respect to the first end face 43 of the third rotating ring 33 in the axial direction X (the left side in FIGS. 1 and 2). ) With a gap from each other. The guide bar 48 provided on the first end face 43 of the second rotating ring 32 is slidably inserted into the guide hole 56 of the second end face 52 (see FIG. 1). Thereby, the second rotary ring 32 is relatively movable along the axial direction X with respect to the third rotary ring 33, while being positioned in the circumferential direction with respect to the third rotary ring 33.

  The urging member 13 is an elastic body (rubber block or spring) extending along the axial direction X, and is a compression spring in this embodiment. The biasing member 13 is fitted into each recess 53 of the third rotating ring 33, and extends along the axial direction X between the bottom surface 55 of the recess 53 and the first end face 43 of the second rotating ring 32. Compressed. That is, the biasing member 13 is interposed between the second rotating ring 32 and the third rotating ring 33 in a compressed state. Since the third rotary ring 33 is positioned in the axial direction X as described above, the biasing member 13 biases the second rotary ring 32 toward the first rotary ring 31. Thereby, since the annular space 47 is narrowed in the axial direction X, the compression of the seal member 60 is promoted, so that the annular space 47 is reliably sealed by the seal member 60. The urging member 13 urges the first rotating ring 31 toward the stationary ring 11 by urging the second rotating ring 32 toward the first rotating ring 31. Therefore, the rotation-side seal surface 37 of the first rotation ring 31 is in pressure contact with the fixed-side seal surface 17 of the fixed ring 11 over the entire circumference. That is, the urging member 13 brings the rotation-side seal surface 37 and the fixed-side seal surface 17 close to each other.

  As described above, the first rotating ring 31 and the second rotating ring 32 are positioned in the circumferential direction, and the second rotating ring 32 and the third rotating ring 33 are positioned in the circumferential direction. That is, the entire rotating ring 12 (a group of the first rotating ring 31, the second rotating ring 32, and the third rotating ring 33) is positioned with respect to the rotating shaft 4 in the circumferential direction. Therefore, when the rotating shaft 4 rotates, the entire rotating ring 12 rotates integrally with the rotating shaft 4. Here, as described above, since the sealing member 60 seals the annular space 47, the fluid R flows between the outer peripheral surface 4 </ b> A of the rotating shaft 4 and the inner peripheral surface of the rotating ring 12 (particularly the second inner surface of the first rotating ring 31. It does not leak to the outside of the housing 3 from between the inner peripheral surface 16 of the stationary ring 11 and the outer peripheral surface 4A of the rotating shaft 4 through the peripheral surface 35B). Therefore, a main path through which the fluid R leaks to the outside is between the rotation-side seal surface 37 of the first rotation ring 31 and the fixed-side seal surface 17 of the fixed ring 11.

  However, in the mechanical seal 1, the biasing member 13 compressed between the second rotating ring 32 and the third rotating ring 33 presses the second rotating ring 32 against the first rotating ring 31, and the first rotating ring 31. The rotation-side seal surface 37 is brought close to (pressure contact) with the fixed-side seal surface 17 of the fixed ring 11. Therefore, as the rotary shaft 4 rotates, the rotation-side seal surface 37 of the first rotation ring 31 rotates (slids) while being in sliding contact with the fixed-side seal surface 17 of the fixed ring 11. As a result, there is no gap through which the fluid R can pass between the rotation-side seal surface 37 and the fixed-side seal surface 17. Therefore, the fluid R leaks to the outside of the housing 3 from between the inner peripheral surface 16 of the stationary ring 11 and the outer peripheral surface 4 </ b> A of the rotating shaft 4 along the rotation-side seal surface 37 and the fixed-side seal surface 17. Is suppressed. That is, in the opening 6 of the housing 3, the fluid R can be prevented from leaking between the fixed-side seal surface 17 and the rotation-side seal surface 37. Further, while the rotary shaft 4 is rotating, the rotary side seal surface 37 and the fixed side seal surface 17 are merely in sliding contact with each other, and the rotary shaft 4 itself is not worn.

  Here, referring to FIG. 2, there is a DLC (Diamond) in the entire area of at least one of the rotation side seal surface 37 of the first rotation ring 31 and the fixed side seal surface 17 of the fixed ring 11 (both in this embodiment). A film (DLC film 14) made of Like Carbon is provided. The DLC film 14 is excellent in corrosion resistance and wear resistance. Therefore, corrosion and wear on the rotation-side seal surface 37 and the fixed-side seal surface 17 can be suppressed. In addition, the rotation-side seal surface 37 that rotates together with the rotation shaft 4 can smoothly follow the fixed-side seal surface 17, so that the fluid R cannot pass through the gap between the rotation-side seal surface 37 and the fixed-side seal surface 17. It can be kept as narrow as possible.

  This DLC film 14 is a special DLC film 14 containing silicon (Si) of more than 0 wt% and not more than 30 wt%. Such a DLC film 14 has a lower coefficient of friction than that which does not contain silicon. In particular, in the case where the DLC film 14 is in a liquid (when immersed in a liquid) as shown in this embodiment, Compared with this, the coefficient of friction is further reduced, and higher wear resistance can be exhibited. In addition, when atomic composition percentage (at%) is used instead of mass percentage (wt%), the DLC film 14 should just contain the silicon more than 0 at% and 30 at% or less.

The fixed ring 11 and the rotary ring 12 (each of the first rotary ring 31, the second rotary ring 32, and the third rotary ring 33) are general-purpose steel (for example, carbon steel, stainless steel, etc., inexpensive and have good workability. Metal material).
When creating the mechanical seal 1, first, the general-purpose steel is processed to a target shape (cutting or the like) to form the stationary ring 11 and the rotating ring 12.

  Next, a low temperature DLC treatment (with a treatment temperature of 200 ° C. or less) is applied to each of the stationary ring 11 and the rotating ring 12 by a direct current plasma chemical vapor deposition (DC) method using an organic silicon compound gas or the like as a source gas. DLC coating). As a result, the DLC film 14 is formed on portions of the fixed ring 11 and the rotating ring 12 where the DLC film 14 is required (at least the rotation-side seal surface 37 and the fixed-side seal surface 17). In this case, compared with the case where the mechanical seal 1 is formed only from ceramics such as SiC, the workability of the entire mechanical seal 1 is good, and the mechanical seal 1 can be produced at low cost. In particular, according to the CVD method, it is possible to perform DLC processing even on a complicated three-dimensional shaped part (particularly, the inner peripheral surface of a hollow part). Furthermore, if it is a low temperature DLC process, since the distortion in the rotating ring 12 (particularly when formed of stainless steel) that rotates integrally with the rotating shaft 4 can be suppressed, the inertial force of the rotating ring 12 during rotation can be reduced. It is possible to suppress the occurrence of shaking (blur) in the rotation of the rotating shaft 4 and the rotating ring 12 as much as possible.

A method for forming the DLC film 14 (such as the aforementioned direct-current pulse plasma CVD method or low-temperature DLC treatment) is described in detail in Japanese Patent Application Laid-Open No. 2012-207243. By adjusting the flow rate ratio of the organic silicon compound gas in the source gas, it is possible to form the DLC film 14 containing more than 0 wt% and 30 wt% or less of silicon.
In addition, although a plastic is mentioned as a raw material which is excellent in corrosion resistance, in the case of the mechanical seal 1 formed with the metal material, even if the fluid R is a high pressure, it is between the rotation side seal surface 37 and the fixed side seal surface 17. The sealability is not easily affected by the pressure of the fluid R, and it has better wear resistance than plastic.

Thus, in the mechanical seal 1, the corrosion resistance, wear resistance, and workability can be improved at a time.
Further, in the first rotating ring 31, an inner peripheral surface (first inner peripheral surface 35 </ b> A) in the recess 38 and a surface (first surface) facing the inner peripheral surface in the insertion portion 46 of the second rotating ring 32 inserted in the recess 38. 2 outer peripheral surface 41B) may come into sliding contact with the movement of the first rotating ring 31 and the second rotating ring 32 in the axial direction X. Therefore, the DLC film 14 may be provided on at least one of the inner peripheral surface and the surface (both in this embodiment). By doing so, it is possible to improve the corrosion resistance and wear resistance of the inner peripheral surface and the surface.

  Further, the DLC film 14 with good corrosion resistance may be provided in each of the stationary ring 11 and the rotating ring 12 in a portion that contacts the fluid R in the hollow portion 5 of the housing 3 in addition to the portion described above. Examples of the portion that contacts (can contact) the fluid R include at least one of the outer peripheral surface 15, the inner peripheral surface 16, the positioning surface 18, and the tapered surface 19 in the stationary ring 11. In the first rotating ring 31, at least one of the outer peripheral surface 34, the inner peripheral surface 35, the positioning surface 36, and the tapered surface 40 is exemplified. In the case of the second rotating ring 32, at least one of the outer peripheral surface 41, the inner peripheral surface 42, the first end surface 43, and the second end surface 44 may be mentioned. In the case of the third rotating ring 33, at least one of the outer peripheral surface 49, the inner peripheral surface 50, the first end surface 51, the second end surface 52, the cylindrical surface 54, and the bottom surface 55 is exemplified. If the DLC film 14 is provided in the portion that contacts the fluid R, corrosion in the portion that contacts the fluid R in each of the stationary ring 11 and the rotating ring 12 can be suppressed.

The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.
For example, the seal member 20 and the seal member 60 are O-rings in the above-described embodiment, but a plurality of V-packings may be stacked as necessary.
In the above-described embodiment, the mechanical seal 1 prevents the fluid R in the hollow portion 5 of the housing 3 from leaking from the opening 6 to the outside of the housing 3. Can also be prevented from entering the hollow portion 5 of the housing 3.

  In this embodiment, the DLC film 14 is provided on both the rotation-side seal surface 37 and the fixed-side seal surface 17, but may be provided on either one. If the DLC film 14 is provided on both, the corrosion resistance and wear resistance of both can be improved. If the DLC film 14 is provided on the one side, the corrosion resistance and wear resistance on the one side can be improved, and the processing cost on the other side can be reduced. This is due to at least one of the inner peripheral surface (first inner peripheral surface 35A) in the recess 38 of the first rotating ring 31 and the surface (second outer peripheral surface 41B) facing the inner peripheral surface in the insertion portion 46. This also applies when the DLC film 14 is provided.

  DESCRIPTION OF SYMBOLS 1 ... Mechanical seal, 3 ... Housing, 4 ... Rotating shaft, 6 ... Opening part, 11 ... Fixed ring, 12 ... Rotating ring, 13 ... Biasing member, 14 ... DLC film, 17 ... Fixed side sealing surface, 31 ... First 1 rotation ring, 32 ... 2nd rotation ring, 33 ... 3rd rotation ring, 35A ... 1st inner peripheral surface, 37 ... rotation side sealing surface, 38 ... hollow, 41B ... 2nd outer peripheral surface, 46 ... insertion part, R ... Fluid, X ... Axial direction

Claims (5)

A mechanical seal for preventing leakage of fluid in the opening between the rotation shaft and a housing formed with an opening through which the rotation shaft is inserted;
A fixed ring that is fixed to the housing at the opening and is externally fitted to the rotating shaft;
A rotating ring that is externally fitted so as to be integrally rotatable with respect to the rotating shaft;
A fixed-side sealing surface provided on the fixed ring and facing the rotary ring in the axial direction of the rotary shaft;
A rotation-side seal surface that is provided on the rotary ring, faces the fixed-side seal surface in the axial direction, and slides on the fixed-side seal surface as the rotation shaft rotates;
An urging member for bringing the rotating side sealing surface and the stationary side sealing surface close to each other;
A DLC film that is provided on at least one of the rotating side sealing surface and the stationary side sealing surface and contains silicon in an amount of more than 0 wt% and not more than 30 wt%;
A mechanical seal comprising: The rotating ring has the rotation-side sealing surface and is arranged on the opposite side of the fixed ring with respect to the first rotating ring in the axial direction, the first rotating ring being movable in the axial direction, A second rotating ring movable in the axial direction,
The biasing member biases the second rotating ring toward the first rotating ring,
The inner peripheral surface of the first rotating ring is formed with a recess facing the second rotating ring side,
The second rotating ring includes an insertion portion to be inserted into the recess,
The DLC film is provided on at least one of an inner peripheral surface of the first rotating ring in the recess and a surface facing the inner peripheral surface in the insertion portion. Mechanical seal. The rotating ring includes a third rotating ring that is disposed on the opposite side of the fixed ring with respect to the second rotating ring in the axial direction and is positioned in the axial direction;
The mechanical seal according to claim 2, wherein the biasing member is interposed between the second rotating ring and the third rotating ring.   The mechanical seal according to any one of claims 1 to 3, wherein the DLC film is provided in a portion of each of the stationary ring and the rotating ring that contacts the fluid.   The mechanical seal according to any one of claims 1 to 4, wherein the stationary ring and the rotating ring are made of general-purpose steel.

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