Mechanical seal

Abstract

The axial dimension of the mechanical seal is shortened while suppressing reduction in the cross-sectional area of ​​the fluid supply passage. [Solution] The mechanical seal is equipped with a supply passage that supplies fluid to the seal surface where the rotating ring and stationary ring slide. The supply passage includes a cover-side supply passage (50) that is provided in the cover member and communicates with the inner circumferential surface of the cover member. The cross-sectional shape of at least a portion of the cover-side supply passage (50) is short in the axial direction (L) and long in the circumferential direction (C).

Description

[Technical Field]

[0001] The present invention relates to a mechanical seal. [Background technology]

[0002] For example, the mechanical seal disclosed in JP 2019-060497 A (Patent Document 1) has supply passages for supplying flushing fluid and quenching fluid into the machine. The flushing fluid is sometimes used to remove heat from the sliding surface, and the quenching fluid is sometimes used for cleaning.

[0003] The supply passages are provided so as to penetrate a cover member that separates the inside and outside of the machine, and the flushing fluid and quenching fluid are supplied from the outside to the inside of the machine. Since the supply passages are formed by drilling holes in the cover member, the cross section of the flow passages is generally a perfect circle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-060497 Summary of the Invention

[0005] However, depending on the market, there is a need for smaller mechanical seals (especially shorter axial dimensions), and one possible way to meet this need is to reduce the diameter of the supply passage. However, if the diameter of the supply passage, i.e., the cross-sectional area of ​​the supply passage, is reduced, the flow velocity of the fluid flowing through the supply passage increases, which can cause erosion inside the device. [Problem to be solved by the invention]

[0006] In view of the above circumstances, it is desirable to reduce the axial dimension of the mechanical seal while suppressing a reduction in the cross-sectional area of ​​the fluid supply passage. [Means for solving the problem]

[0007] a rotating ring that rotates integrally with the rotating shaft; a fixed ring disposed adjacent to the rotary ring in the axial direction; a cover member disposed radially outward relative to at least one of the rotating ring and the stationary ring, a supply passage for supplying a fluid to a seal surface where the rotary ring and the stationary ring slide, the supply passage includes a cover-side supply passage that is provided in the cover member and communicates with an inner circumferential surface of the cover member, At least a portion of the cover-side supply passage has a cross-sectional shape that is short in the axial direction and long in the circumferential direction.

[0008] According to this configuration, the cross-sectional shape of the cover-side supply passage is shortened in the axial direction. This allows the axial dimension of the cover member, etc., in which the cover-side supply passage is provided, to be shortened, thereby enabling the axial dimension of the entire mechanical seal to be shortened. At the same time, the cross-sectional shape of the cover-side supply passage is elongated in the circumferential direction, thereby preventing a reduction in the cross-sectional area of ​​the cover-side supply passage. In other words, a reduction in the cross-sectional area of ​​the cover-side supply passage due to the short cross-sectional shape of the cover-side supply passage in the axial direction can be prevented. As described above, according to this configuration, the axial dimension of the mechanical seal can be shortened while preventing a reduction in the cross-sectional area of ​​the fluid supply passage.

[0009] Further features and advantages of the techniques according to the present disclosure will become more apparent from the following description of exemplary and non-limiting embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0010] [Figure 1] Cross section of a mechanical seal [Figure 2] View of arrow II in Figure 1 [Figure 3] 10 is a cross-sectional view of a mechanical seal according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] A mechanical seal is a device for sealing the periphery of a rotating shaft in a rotating machine such as a pump. Hereinafter, an embodiment of the mechanical seal will be described with reference to the drawings.

[0012] [First embodiment] First, a first embodiment of the mechanical seal will be described.

[0013] As shown in FIG. 1, the mechanical seal 100 is attached to a rotating shaft 98 that passes through a case 99 of a rotating device.

[0014] In the following, the "axial direction L," "radial direction R," and "circumferential direction C" are defined based on the axis Ax of the rotating shaft 98. One side in the axial direction L is defined as the "first axial side L1," and the other side is defined as the "second axial side L2."

[0015] The mechanical seal 100 includes a rotating ring 2 that rotates integrally with the rotating shaft 98, a stationary ring 1 disposed adjacent to the rotating ring 2 in the axial direction L, and a cover member 4 disposed radially outward of at least one of the rotating ring 2 and the stationary ring 1. In the illustrated example, the rotating ring 2 is disposed on the second axial side L2 relative to the stationary ring 1. The stationary ring 1 is disposed on the first axial side L1 relative to the rotating ring 2.

[0016] The cover member 4 is formed in a cylindrical shape and is configured to cover the interior of the rotating device (hereinafter simply referred to as the “interior”), which is the area to be sealed by the mechanical seal 100, from the outside in the radial direction R.

[0017] The rotary shaft 98 passes through the case 99 and is connected to a rotary drive source (not shown) at the end in the axial direction L. Examples of the rotary drive source include an electric motor and an engine.

[0018] The fixed ring 1 is fixed to the cover member 4 (or the case 99) so as not to be rotatable. In this embodiment, the fixed ring 1 is a seal ring, and is configured to be movable in the axial direction L by being biased by a biasing member 95 held by a retainer 97. An example of the biasing member 95 is a spring. However, the biasing member 95 can also be configured using a bellows.

[0019] The rotary ring 2 is configured to rotate integrally with the rotary shaft 98. The rotary ring 2 is a mating ring whose position in the axial direction L is fixed. In this embodiment, a sleeve 3 is provided on the outer peripheral surface of the rotary shaft 98, and the rotary ring 2 is held by the sleeve 3. In this example, the rotary ring 2 is disposed inside the cylindrical holding portion 32 of the sleeve 3 in the radial direction R, and is held at that position.

[0020] As described above, in the illustrated example, the stationary ring 1 is disposed on the first axial side L1 relative to the rotatable ring 2. The rotatable ring 2 is disposed on the second axial side L2 relative to the stationary ring 1. The surface of the stationary ring 1 facing the second axial side L2 and the surface of the rotatable ring 2 facing the first axial side L1 face each other in the axial direction L. When the stationary ring 1 is biased toward the second axial side L2 by the biasing member 95, the surfaces of the stationary ring 1 and the rotatable ring 2 that face each other in the axial direction L slide against each other to form a seal surface S, thereby suppressing fluid leakage. Note that the stationary ring 1 and the rotatable ring 2 should preferably be made of a material whose main component is carbon or SIC with a relatively low hardness.

[0021] In the illustrated example, a retaining ring 96 that holds the fixed ring 1 is provided between the fixed ring 1 and the biasing member 95 in the axial direction L. The fixed ring 1 is configured to be biased by the biasing member 95 via the retaining ring 96.

[0022] Here, the seal surface S where the fixed ring 1 and the rotating ring 2 slide against each other and its surroundings are prone to become hot due to friction. Therefore, a flushing fluid is used to cool these areas. The flushing fluid may be the same as the sealed fluid, or a different fluid such as cooling water may be used. As a flushing method, a through-flushing method or a self-flushing method can be suitably used.

[0023] The mechanical seal 100 is provided with a supply passage 5 that supplies fluid to the seal surface S where the rotating ring 2 and the fixed ring 1 slide. This makes it possible to cool the seal surface S and its surroundings, which tend to become hot due to friction.

[0024] The supply path 5 includes a cover-side supply path 50 that is provided in the cover member 4 and communicates with the inner circumferential surface 4Fi of the cover member 4. In this embodiment, the cover-side supply path 50 includes a large supply path 51 that opens onto the outer circumferential surface 4Fo of the cover member 4, and a small supply path 52 that continues inward in the radial direction R from the large supply path 51 and has a smaller flow path cross-sectional area than the large supply path 51. That is, in this example, the large supply path 51 opens onto the outer circumferential surface 4Fo of the cover member 4, and the small supply path 52 opens onto the inner circumferential surface 4Fi of the cover member 4, so that the cover-side supply path 50 communicates between the outside of the machine (outside the rotating device) and the inside of the machine.

[0025] For example, the large supply passage 51 serves as a connection port for piping from outside the machine. In the illustrated example, the large supply passage 51 is formed to extend parallel to the radial direction R. This allows the formation range of the large supply passage 51 to be limited to the axial direction L, making it easy to shorten the axial dimension of the mechanical seal 100. However, the extension direction of the large supply passage 51 may be set appropriately depending on the manner of connection with the piping, and does not have to be parallel to the radial direction R.

[0026] The small supply passage 52 is a flow path that continues inward in the radial direction R with respect to the large supply passage 51, and opens to the inner circumferential surface 4Fi of the cover member 4. In other words, the small supply passage 52 is a flow path that directly supplies fluid into the interior of the device. The detailed configuration of the small supply passage 52 will be described later.

[0027] An internal flow path 6 is provided inward of the cover member 4 in the radial direction R. The seal surface S is provided in the internal flow path 6. This allows the seal surface S to be cooled by the fluid flowing through the internal flow path 6.

[0028] The in-machine flow path 6 includes a fixed-side in-machine region 61 provided on the first axial side L1 of the fixed ring 1, and a rotating-side in-machine region 62 provided on the second axial side L2 (the side on which the rotating ring 2 is arranged) of the fixed ring 1. The fluid supplied from the supply path 5 to the in-machine flow path 6 passes through the fixed-side in-machine region 61 to cool the seal surface S, and then flows through the rotating-side in-machine region 62 and is discharged outside the machine.

[0029] In this embodiment, the fixed-side internal area 61 includes an adapter ring through-hole 94h that is a through-hole formed in the adapter ring 94, and a fixed ring through-hole 1h that is a through-hole formed in the fixed ring 1.

[0030] The adapter ring through-hole 94h penetrates a portion of the adapter ring 94 in the radial direction R. The stationary ring through-hole 1h penetrates a portion of the stationary ring 1 in the axial direction L. The fluid supplied from the supply passage 5 to the interior of the aircraft passes through the adapter ring through-hole 94h toward the inside in the radial direction R, then passes through the stationary ring through-hole 1h from the first axial side L1 to the second axial side L2, and reaches the seal surface S.

[0031] Here, depending on the market, there is a need for smaller mechanical seals, particularly for shorter axial dimensions. To meet this need, it is conceivable to reduce the diameter of the supply passage. Generally, the supply passage is formed by drilling a hole in a cover member, and the flow passage cross section is often a perfect circle. Therefore, the diameter of the supply passage can be reduced by drilling a smaller, perfect circle-shaped hole in the cover member. This allows the axial dimension of the cover member to be shortened, and ultimately the axial dimension of the mechanical seal to be shortened.

[0032] However, when the hole diameter of the supply passage is reduced, the cross-sectional area of ​​the passage also becomes smaller, which increases the flow rate of the fluid flowing through the supply passage, causing another problem of erosion inside the device.

[0033] Therefore, it is necessary to reduce the axial dimension of the mechanical seal while maintaining the flow passage cross-sectional area of ​​the supply passage.

[0034] Fig. 2 is a view taken along the arrow II in Fig. 1. In other words, it is a view of the supply passage 5 as seen from the outside in the radial direction R.

[0035] 2, the cross-sectional shape of at least a part of the cover-side supply path 50 is short in the axial direction L and long in the circumferential direction C. In this embodiment, the cross-sectional shape of the small supply path 52 is short in the axial direction L and long in the circumferential direction C (a vertically elongated shape in FIG. 2). In other words, the axial dimension of the cross-section of the flow path is at least shorter than the circumferential dimension of the cross-section of the flow path.

[0036] With this configuration, the axial dimension of the cover member 4 in which the cover-side supply passage 50 is provided can be made shorter than when the flow passage cross-sectional shape is a perfect circle, and ultimately the axial dimension of the entire mechanical seal 100 can be made shorter. At the same time, because the flow passage cross-sectional shape of the cover-side supply passage 50 is long in the circumferential direction C, it is possible to prevent a reduction in the flow passage cross-sectional area of ​​the cover-side supply passage 50. In other words, it is possible to prevent a reduction in the flow passage cross-sectional area due to the flow passage cross-sectional shape of the cover-side supply passage 50 being short in the axial direction L.

[0037] In this embodiment, the cross-sectional shape of the small supply passage 52 is an ellipse extending in the circumferential direction C. To form the cover member 4 provided with the small supply passage 52 having such a cross-sectional shape, it is preferable to use a technique such as a 3D printer.

[0038] In this embodiment, the flow path cross-sectional area of ​​the small supply path 52 is set based on the flow rate and flow velocity of the fluid.

[0039] Here, the relationship between the flow path cross-sectional area, the flow rate, and the flow velocity is expressed by the following equation (1). Fluid flow velocity = Fluid flow rate / Cross-sectional area of ​​supply channel (1)

[0040] In this embodiment, among the flow velocity, flow rate, and flow path cross-sectional area, the flow rate is set first, then the flow velocity is set, and finally the flow path cross-sectional area is set based on the flow rate and flow velocity. That is, the flow rate setting, flow velocity setting, and flow path cross-sectional area setting are performed in this order.

[0041] The flow rate is set to an amount necessary to adequately cool the cooling target area, centered on the seal surface S. This flow rate may be set to an appropriate value through repeated testing or the like, or may be set to any value desired by the user.

[0042] The flow rate is set to a value that does not cause erosion inside the device. For example, the flow rate is not set to a unique value, but is set to a range of values ​​within a range in which erosion does not occur. This flow rate may be set to an appropriate value through repeated testing, etc.

[0043] Next, the flow path cross-sectional area is set based on the flow rate and flow velocity. As described above, the flow rate has already been set as the amount required for cooling. Therefore, as shown in the above formula (1), the flow velocity, which is a range value, decreases as the flow path cross-sectional area increases, and increases as the flow path cross-sectional area decreases. The flow path cross-sectional area is then set to a value that can achieve the set flow velocity.

[0044] In this embodiment, the flow path cross-sectional area is set so that the range value of the flow velocity is at or near the upper limit value. In other words, the flow path cross-sectional area is set to a small value so that the flow velocity is as high as possible without causing erosion.

[0045] As shown in FIG. 1, in this embodiment, the inlet 52a of the small supply passage 52 is positioned offset in the axial direction L from the seal surface S, and the outlet 52b of the small supply passage 52 is positioned closer to the seal surface S in the axial direction L than the inlet 52a. In other words, the small supply passage 52 is configured to be inclined with respect to the radial direction R toward the seal surface S. This makes it easier to supply fluid to the seal surface S, which is the area to be cooled, and makes it possible to improve the cooling efficiency at that area. The inlet 52a of the small supply passage 52 is the connection portion of the small supply passage 52 with the large supply passage 51. The outlet 52b of the small supply passage 52 is the opening portion of the small supply passage 52 to the interior of the machine.

[0046] Second Embodiment Next, a second embodiment of the mechanical seal will be described.

[0047] The following mainly describes the differences from the first embodiment described above, with reference to Fig. 3. Items that are not particularly described are the same as those in the first embodiment.

[0048] 3, this embodiment is provided with a discharge path 7 that discharges the fluid supplied to the seal surface S. The discharge path 7 is provided in the cover member 4 and includes a cover-side discharge path 70 that communicates with the inner circumferential surface of the cover member 4.

[0049] In this embodiment, the cover member 4 includes a first cover member 41 and a second cover member 42. The first cover member 41 and the second cover member 42 are arranged side by side along the axial direction L (in the illustrated example, an intermediate cover member is arranged between them).

[0050] The first cover member 41 is disposed on the first axial side L1 of the seal surface S. The first cover member 41 is provided with a supply passage 5 for supplying fluid to the seal surface S.

[0051] The second cover member 42 is disposed on the second axial side L2 relative to the seal surface S. The second cover member 42 is provided with a discharge path 7 that discharges the fluid supplied to the seal surface S. The cover-side discharge path 70 described above is provided in the second cover member 42.

[0052] The cross-sectional shape of at least a part of the cover-side discharge path 70 is short in the axial direction L and long in the circumferential direction C. In this embodiment, the cover-side discharge path 70 includes a large supply path 71 that opens onto the outer peripheral surface of the second cover member 42, and a small supply path 72 that continues inward in the radial direction R relative to the large supply path 71 and has a smaller cross-sectional area than the large supply path 71. The cross-sectional shape of the small supply path 72 is short in the axial direction L and long in the circumferential direction C. Although not shown in detail, the cross-sectional shape of the small supply path 72 in the cover-side discharge path 70 is an ellipse extending in the circumferential direction C, similar to the cross-sectional shape of the small supply path 52 in the cover-side supply path 50.

[0053] In this way, in the mechanical seal 100 having the discharge passage 7 in addition to the supply passage 5, the flow path cross-sectional shapes of both the supply passage 5 and the discharge passage 7 can be shortened in the axial direction L, making it possible to further shorten the axial dimension of the mechanical seal 100 as a whole.

[0054] In addition, in this embodiment, the inlet 72a of the small supply passage 72 is positioned offset in the axial direction L from the seal surface S, and the outlet 72b of the small supply passage 72 is positioned closer to the seal surface S in the axial direction L than the inlet 72a. In other words, the small supply passage 72 is configured to be inclined toward the seal surface S with respect to the radial direction R. This makes it easier for the fluid that passes through the seal surface S from the first axial side L1 to the second axial side L2 to be guided to the small supply passage 72 as it is and discharged outside the apparatus.

[0055] Other Embodiments Next, other embodiments will be described.

[0056] (1) In the above embodiment, an example has been described in which the flow path cross-sectional shape of the small supply path 52 is an ellipse extending in the circumferential direction C. However, this is not limited to such an example. The flow path cross-sectional shape of the small supply path 52 may be a rectangle extending in the circumferential direction C. Even a small supply path 52 having such a shape can be appropriately formed by using, for example, a 3D printer.

[0057] (2) In the above embodiment, an example has been described in which the large supply passage 51 is formed to extend parallel to the radial direction R. However, the present invention is not limited to this example. The large supply passage 51 may be formed to extend obliquely with respect to the radial direction R.

[0058] (3) In the above embodiment, an example in which a flushing fluid is used as the fluid has been described. However, the present invention is not limited to such an example. A quenching fluid may be used as the fluid, or a gas may be used instead of a liquid.

[0059] (4) The configurations disclosed in the above-described embodiments can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate within the scope of the present disclosure.

[0060] [Summary of this embodiment] The summary of this embodiment will be described below.

[0061] a rotating ring that rotates integrally with the rotating shaft; a fixed ring disposed adjacent to the rotary ring in the axial direction; a cover member disposed radially outward relative to at least one of the rotating ring and the stationary ring, a supply passage for supplying a fluid to a seal surface where the rotary ring and the stationary ring slide, the supply passage includes a cover-side supply passage that is provided in the cover member and communicates with an inner circumferential surface of the cover member, At least a portion of the cover-side supply passage has a cross-sectional shape that is short in the axial direction and long in the circumferential direction.

[0062] According to this configuration, the cross-sectional shape of the cover-side supply passage is shortened in the axial direction. This allows the axial dimension of the cover member, etc., in which the cover-side supply passage is provided, to be shortened, thereby enabling the axial dimension of the entire mechanical seal to be shortened. At the same time, the cross-sectional shape of the cover-side supply passage is elongated in the circumferential direction, thereby preventing a reduction in the cross-sectional area of ​​the cover-side supply passage. In other words, a reduction in the cross-sectional area of ​​the cover-side supply passage due to the short cross-sectional shape of the cover-side supply passage in the axial direction can be prevented. As described above, according to this configuration, the axial dimension of the mechanical seal can be shortened while preventing a reduction in the cross-sectional area of ​​the fluid supply passage.

[0063] the cover-side supply passage includes a large supply passage that opens to an outer peripheral surface of the cover member, and a small supply passage that is continuous with the large supply passage radially inward and has a flow path cross-sectional area smaller than that of the large supply passage, It is preferable that the small supply passage has a cross-sectional shape that is short in the axial direction and long in the circumferential direction.

[0064] In this configuration, the large supply passage that opens to the outer peripheral surface of the cover member is limited in size due to the need to connect to piping outside the machine. Therefore, by providing a small supply passage, which has a relatively high degree of design freedom, continuous with the large supply passage, the small supply passage can be used to shorten the axial dimension and maintain the flow passage cross-sectional area.

[0065] the inlet of the small supply passage is axially offset relative to the sealing surface; Preferably, the outlet of the small supply passage is arranged at a position axially closer to the seal surface than the inlet.

[0066] According to this configuration, it becomes easier to supply fluid to the sealing surface, which is the area to be cooled, and the cooling efficiency at that area can be improved.

[0067] Preferably, the large supply passage is formed so as to extend parallel to the radial direction.

[0068] According to this configuration, the area in which the large supply passage is formed can be reduced in the axial direction, making it possible to further reduce the axial dimension of the mechanical seal.

[0069] a discharge passage for discharging the fluid supplied to the seal surface; the discharge path includes a cover-side discharge path that is provided in the cover member and communicates with an inner circumferential surface of the cover member, It is preferable that the cross-sectional shape of at least a part of the cover-side discharge passage is short in the axial direction and long in the circumferential direction.

[0070] According to this configuration, in a mechanical seal having a discharge passage in addition to a supply passage, the flow path cross-sectional shapes of both the supply passage and the discharge passage can be shortened in the axial direction, making it possible to further shorten the axial dimension of the mechanical seal. [Industrial Applicability]

[0071] The technology according to the present disclosure can be used in mechanical seals. [Explanation of symbols]

[0072] 100: Mechanical seal 1: Fixed ring 2: Rotating ring 4: Cover material 4Fi: Inner surface 4Fo: Outer surface 5: Supply route 50: Cover side supply path 51: Great supply route 52: Small supply route 52a: Entrance 52b:Exit 7:Exhaust channel 70: Cover side discharge channel 71: Great supply route 72: Small supply road 72a: Entrance 72b :Exit 8: Rotation axis S: Sealing surface L: Axial direction R: Radial direction C: Circumferential direction

Claims

1. a rotating ring that rotates integrally with the rotating shaft; a fixed ring disposed adjacent to the rotary ring in the axial direction; a cover member disposed radially outward relative to at least one of the rotating ring and the stationary ring, a supply passage for supplying a fluid to a seal surface where the rotary ring and the stationary ring slide, the supply passage includes a cover-side supply passage that is provided in the cover member and communicates with an inner circumferential surface of the cover member, A mechanical seal in which, in at least a portion of the cover-side supply passage, the shape of the flow passage cross section obtained by cutting the cover-side supply passage along a plane perpendicular to the longitudinal direction of the cover-side supply passage is short in the axial direction and long in the circumferential direction.

2. the cover-side supply passage includes a large supply passage that opens to an outer peripheral surface of the cover member, and a small supply passage that is continuous with the large supply passage radially inward and has a flow passage cross-sectional area that is smaller than the area of ​​the flow passage cross section of the large supply passage, 2. The mechanical seal according to claim 1, wherein the small supply passage has a cross-sectional shape that is short in the axial direction and long in the circumferential direction.

3. the inlet of the small supply passage is axially offset relative to the sealing surface; The mechanical seal according to claim 2 , wherein the outlet of the small supply passage is located axially closer to the seal face than the inlet.

4. 4. The mechanical seal according to claim 3, wherein the large supply passage is formed so as to extend parallel to the radial direction.

5. a discharge passage for discharging the fluid supplied to the seal surface; the discharge path includes a cover-side discharge path that is provided in the cover member and communicates with an inner circumferential surface of the cover member, The mechanical seal according to claim 1 , wherein a cross-sectional shape of the passage in at least a part of the cover-side discharge passage is short in the axial direction and long in the circumferential direction.

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