WO2024084798A1

WO2024084798A1 - Pump and pump assembly method

Info

Publication number: WO2024084798A1
Application number: PCT/JP2023/030303
Authority: WO
Inventors: 潤也川畑; 健太宮
Original assignee: 株式会社荏原製作所
Priority date: 2022-10-20
Filing date: 2023-08-23
Publication date: 2024-04-25
Also published as: JP2024060895A

Abstract

The present invention relates to a pump for a liquid and particularly relates to a pump having a mechanical seal disposed on a rotating shaft. A pump (P) includes: a retainer (41) held by a spring (33) that presses a rotating ring (31) of a mechanical seal (20) against a stationary ring (32) thereof; and a retainer holder (50) attached to a back side of an impeller (2). The retainer holder (50) has: a peripheral wall (52) inside which the retainer (41) is fitted; and a bottom wall (53) that extends radially inward from the peripheral wall (52). The peripheral wall (52) protrudes from the bottom wall (53) toward the mechanical seal (20). The peripheral wall (52) has a tapered surface (54) formed at an edge thereof. The tapered surface (54) has a truncated cone shape in which the inner diameter of the peripheral wall (52) increases with increasing the distance from the bottom wall (53).

Description

Pump and pump assembly method

The present invention relates to a pump for liquids, and in particular to a pump having a mechanical seal arranged on a rotating shaft.

FIG. 9 is a cross-sectional view showing a part of the pump. As shown in FIG. 9, the pump has an impeller 500, a rotating shaft 501 that supports the impeller 500, and a mechanical seal 503 attached to the rotating shaft 501. The impeller 500, the rotating shaft 501, and the mechanical seal 503 are arranged in a pump casing 505. The impeller 500 is fixed to the end of the rotating shaft 501 by a screw 504. The impeller 500 can rotate integrally with the rotating shaft 501.

The mechanical seal 503 has a stationary ring 506 fixed to the pump casing 505, a rotating ring 507 fixed to the rotating shaft 501, and a spring 509 that presses the rotating ring 507 against the stationary ring 506. The spring 509 is arranged to surround the rotating shaft 501. A retainer 510 is fitted to the end of the spring 509, and the retainer 510 contacts a boss portion 511 of the impeller 500. The retainer 510 is an annular member and has an L-shaped cross section.

FIGS. 10 and 11 are exploded views of the pump shown in FIG. 9 when it is assembled. As shown in FIG. 10, the retainer 510 is supported on the tip of the stretched spring 509. The retainer 510 is located outside the step 501a of the rotating shaft 501. The impeller 500 is brought close to the rotating shaft 501, and as shown in FIG. 11, the boss 511 of the impeller 500 pushes the retainer 510 toward the mechanical seal 503. The impeller 500 contracts the spring 509 via the retainer 510, while moving the retainer 510 toward the rotating ring 507 of the mechanical seal 503. The impeller 500 is then fixed to the end of the rotating shaft 501 by the screw 504, thereby completing the pump shown in FIG. 9.

Japanese Utility Model Publication No. 2-23838 Japanese Utility Model Application Publication No. 63-59267 Japanese Patent Application Laid-Open No. 9-177696

However, as shown in FIG. 10, before the pump is assembled, the retainer 510 is only supported by the spring 509, and the position of the retainer 510 is unstable. More specifically, the retainer 510 held at the tip of the spring 509 may not be concentric with the rotating shaft 501. When the retainer 510 is pushed toward the mechanical seal 503 by the impeller 500 in a state in which the retainer 510 is not concentric with the rotating shaft 501, the inner periphery of the retainer 510 is pinched between the step portion 501a of the rotating shaft 501 and the boss portion 511 of the impeller 500, as shown in FIG. 12. As a result, the impeller 500 and the retainer 510 cannot move any further toward the mechanical seal 503. Furthermore, excessive force was applied to the retainer 510 sandwiched between the step 501a of the rotating shaft 501 and the boss 511 of the impeller 500, which could cause the retainer 510 to break.

The present invention provides a pump that can prevent the retainer from being pinched between the impeller and the step of the rotating shaft when assembling the pump. The present invention also provides a method for assembling such a pump.

In one aspect, a pump is provided that includes a rotating shaft, an impeller fixed to the rotating shaft, a mechanical seal arranged to surround the rotating shaft, a retainer held by a spring that presses a rotating ring of the mechanical seal against a stationary ring, and a retainer holder attached to the rear side of the impeller, the retainer holder having a peripheral wall into which the retainer is fitted and a bottom wall extending radially inward from the peripheral wall, the peripheral wall protruding from the bottom wall toward the mechanical seal, the peripheral wall having a tapered surface formed on its edge, and the tapered surface having a truncated cone shape in which the inner diameter of the peripheral wall increases with distance from the bottom wall.

In one aspect, the retainer holder is concentric with the impeller and the axis of rotation.
In one aspect, the retainer has an end wall that contacts the end of the spring and a cylindrical wall that protrudes from the end wall toward the rotating ring of the mechanical seal, and the inner surface of the peripheral wall of the retainer holder contacts the outer surface of the cylindrical wall of the retainer.
In one embodiment, the rotating shaft has a step on its outer circumferential surface, and the retainer is positioned between the step and the rotating ring of the mechanical seal.
In one embodiment, the rotating shaft has a main shaft and a cylindrical shaft sleeve attached to the outer peripheral surface of the main shaft, the rotating ring and the stationary ring of the mechanical seal surround the outer peripheral surface of the shaft sleeve, and the step portion of the rotating shaft is formed by the end face of the shaft sleeve.
In one embodiment, the retainer holder is attached to a boss portion of the impeller.
In one aspect, the pump further includes a screw for fixing the impeller to an end of the rotating shaft, a first seal for sealing a gap between the impeller and the screw, and a second seal for sealing a gap between an inner circumferential surface of the boss portion of the impeller and an outer circumferential surface of the shaft sleeve.

In one aspect, a method of assembling a pump is provided that includes the steps of moving an impeller and a retainer holder attached to the back side of the impeller along a rotation axis toward a mechanical seal, holding a retainer held by a spring that presses a rotating ring of the mechanical seal against a stationary ring by a bottom wall and a peripheral wall of the retainer holder, and, with the retainer held by the retainer holder, further moving the impeller, the retainer holder, and the retainer along the rotation axis toward the rotating ring of the mechanical seal, and fixing the impeller to an end of the rotation axis with a screw, and the peripheral wall has a tapered surface formed on its edge, and the tapered surface has a truncated cone shape in which the inner diameter of the peripheral wall increases with the distance from the bottom wall.

When the pump is assembled, the retainer is held by the retainer holder, and the position of the retainer is fixed by the retainer holder. Therefore, the retainer does not come into contact with the step of the rotating shaft, and the retainer can move integrally with the retainer holder toward the rotating ring of the mechanical seal.

FIG. 1 illustrates an embodiment of a pump device. FIG. 2 is an enlarged view of a portion of the pump shown in FIG. FIG. 3A is a top view of one embodiment of a retainer. FIG. 3B is a cross-sectional view of the retainer shown in FIG. 3A. FIG. 4A is a plan view showing one embodiment of a retainer holder. FIG. 4B is a cross-sectional view of the retainer holder shown in FIG. 4A. 1A to 1C are diagrams illustrating an embodiment of a method for assembling a pump. 1A to 1C are diagrams illustrating an embodiment of a method for assembling a pump. 1A to 1C are diagrams illustrating an embodiment of a method for assembling a pump. 1A to 1C are diagrams illustrating an embodiment of a method for assembling a pump. FIG. 2 is a cross-sectional view showing a part of a pump. FIG. 10 is an exploded view of the pump shown in FIG. 9 when assembled. FIG. 10 is an exploded view of the pump shown in FIG. 9 when assembled. 10 is a diagram illustrating a state in which the inner periphery of the retainer shown in FIG. 9 is sandwiched between a step portion of the rotary shaft and a boss portion of the impeller. FIG.

Embodiments of the present invention will now be described with reference to the drawings. Fig. 1 is a diagram showing one embodiment of a pump device. As shown in Fig. 1, the pump device includes a pump P that transfers a liquid, and an electric motor M that drives the pump P. The pump P includes a rotating shaft 1, an impeller 2 fixed to the rotating shaft 1, and a pump casing 10 that houses the impeller 2. The rotating shaft 1 is connected to the electric motor M and is rotated by the electric motor M. The impeller 2 is fixed to the end of the rotating shaft 1 by a screw 11.

The pump casing 10 has a suction port 14 and a discharge port 15. When the electric motor M is operated, the impeller 2 inside the pump casing 10 rotates, and liquid is sucked into the pump casing 10 through the suction port 14. The liquid sucked into the pump casing 10 is pressurized by the rotation of the impeller 2, and is discharged outside the pump casing 10 through the discharge port 15.

The rotating shaft 1 has a main shaft 3 to which the impeller 2 is fixed, and a cylindrical shaft sleeve 4 attached (fitted) to the outer circumferential surface of the main shaft 3. The main shaft 3 and the shaft sleeve 4 can rotate together. The pump P further includes a mechanical seal 20 arranged to surround the rotating shaft 1. The mechanical seal 20 is a shaft sealing device that seals the gap between the rotating shaft 1 and the pump casing 10, and is configured to prevent liquid from leaking to the electric motor M.

FIG. 2 is an enlarged view of a portion of the pump P shown in FIG. 1. As shown in FIG. 2, the impeller 2 includes a disk-shaped main plate 25, a side plate 26 having a liquid inlet, a plurality of blades 27 arranged between the main plate 25 and the side plate 26, and a boss portion 28 connected to the main plate 25. The mechanical seal 20 includes a rotating ring 31 attached to the rotating shaft 1, a stationary ring 32 fixed to the pump casing 10, and a spring 33 that presses the rotating ring 31 against the stationary ring 32. In this embodiment, the rotating ring 31 is attached to the shaft sleeve 4 of the rotating shaft 1 and can rotate integrally with the shaft sleeve 4. The rotating ring 31 and the stationary ring 32 surround the outer circumferential surface of the shaft sleeve 4.

The pump P further includes a retainer 41 held by the spring 33 of the mechanical seal 20, and a retainer holder 50 attached to the back side of the impeller 2. The retainer holder 50 has a peripheral wall 52 and a bottom wall 53 that form a space into which the retainer 41 is fitted. The peripheral wall 52 protrudes from the bottom wall 53 toward the rotating ring 31 of the mechanical seal 20. The peripheral wall 52 has a tapered surface 54 formed on its edge. The tapered surface 54 has a truncated cone shape in which the inner diameter of the peripheral wall 52 increases with the distance from the bottom wall 53. In this embodiment, the retainer holder 50 is attached to the boss portion 28 of the impeller 2. In one embodiment, the retainer holder 50 is fitted to the boss portion 28 of the impeller 2. The retainer holder 50 is concentric with the impeller 2 and the rotating shaft 1.

The boss portion 28 has a shaft insertion hole 60 formed in its center, into which the main shaft 3 can be inserted, a fastening hole 61 that communicates with the shaft insertion hole 60 and into which the screw 11 can be inserted, and a sleeve insertion hole 62 that communicates with the shaft insertion hole 60 and into which the shaft sleeve 4 can be inserted. The fastening hole 61, shaft insertion hole 60, and sleeve insertion hole 62 are aligned in this order in a straight line along the axial direction of the rotating shaft 1. When the screw 11 is tightened with the main shaft 3 of the rotating shaft 1 inserted into the shaft insertion hole 60, the impeller 2 is fixed to the end of the rotating shaft 1, and the shaft sleeve 4 is inserted into the sleeve insertion hole 62.

The rotating shaft 1 has a step 1a on its outer circumferential surface, and the retainer 41 is located between the step 1a and the rotating ring 31 of the mechanical seal 20. In this embodiment, the step 1a of the rotating shaft 1 is formed from the end face of the shaft sleeve 4. In another embodiment, the rotating shaft 1 does not have a shaft sleeve 4, and the step 1a of the rotating shaft 1 may be a step of the main shaft 3 itself.

The pump P further includes a first seal 66 that seals the gap between the impeller 2 and the screw 11, and a second seal 67 that seals the gap between the inner circumferential surface of the boss portion 28 of the impeller 2 (the surface that forms the sleeve insertion hole 62) and the outer circumferential surface of the shaft sleeve 4. The first seal 66 is, for example, a seal washer or an O-ring, and the second seal 67 is, for example, an O-ring.

Carbon steel (e.g., S45C) may be used as the material for the main shaft 3. Carbon steel may corrode when it comes into contact with liquid. The first seal 66 and the second seal 67 reliably prevent liquid from coming into contact with the main shaft 3, and can prevent corrosion of the main shaft 3. As a result, the lifespan and maintainability of the pump P can be improved.

3A is a plan view showing one embodiment of the retainer 41, and FIG. 3B is a cross-sectional view of the retainer 41 shown in FIG. 3A. The retainer 41 has an end wall 71 that contacts the end of the spring 33 (see FIG. 2) and a cylindrical wall 72 connected to the end wall 71. The end wall 71 is perpendicular to the axial direction of the rotating shaft 1 (see FIG. 2), and the cylindrical wall 72 protrudes from the end wall 71 in a direction parallel to the axial direction of the rotating shaft 1. The cylindrical wall 72 protrudes from the outer periphery of the end wall 71 toward the rotating ring 31 (see FIG. 2) of the mechanical seal 20. The end wall 71 has an annular shape. The inner diameter of the end wall 71 is larger than the outer diameter of the shaft sleeve 4 (see FIG. 2). The retainer 41 is made of a metal such as stainless steel.

FIG. 4A is a plan view showing one embodiment of the retainer holder 50, and FIG. 4B is a cross-sectional view of the retainer holder 50 shown in FIG. 4A. The retainer holder 50 has a peripheral wall 52 into which the retainer 41 is fitted, and a bottom wall 53 extending radially inward from the peripheral wall 52. The peripheral wall 52 is connected to the outer periphery of the bottom wall 53, and protrudes from the outer periphery of the bottom wall 53 toward the rotating ring 31 (see FIG. 2) of the mechanical seal 20. The bottom wall 53 and the peripheral wall 52 form an integral structure. The bottom wall 53 has an annular shape and is perpendicular to the axial direction of the rotating shaft 1. The peripheral wall 52 protrudes from the bottom wall 53 in a direction parallel to the axial direction of the rotating shaft 1.

The inner diameter D1 of the peripheral wall 52 is slightly larger than the outer diameter of the cylindrical wall 72 of the retainer 41. When the retainer 41 is held by the peripheral wall 52 and bottom wall 53 of the retainer holder 50, the inner surface of the peripheral wall 52 of the retainer holder 50 contacts the outer surface of the cylindrical wall 72 of the retainer 41, thereby aligning the retainer 41 and the retainer holder 50 concentrically (positioning of the retainer 41 is achieved). The inner diameter D2 of the bottom wall 53 is larger than the outer diameter of the rotating shaft 1, more specifically, the outer diameter of the shaft sleeve 4 (see FIG. 2). The tapered surface 54 formed on the edge of the peripheral wall 52 is inclined radially outward of the peripheral wall 52. The retainer holder 50 is made of a metal such as aluminum, stainless steel, or cast iron.

Next, one embodiment of a method for assembling the pump P will be described with reference to FIGS.
5, the impeller 2 and the retainer holder 50 attached to the back side of the impeller 2 are moved toward the rotating shaft 1, and the main shaft 3 of the rotating shaft 1 is inserted into the shaft insertion hole 60 of the boss portion 28 of the impeller 2. The retainer 41 is held by the end of the spring 33 of the mechanical seal 20.

As shown in FIG. 6, the impeller 2 and the retainer holder 50 are moved along the rotating shaft 1 toward the rotating ring 31 of the mechanical seal 20 until the retainer 41 is held by the peripheral wall 52 and bottom wall 53 of the retainer holder 50. Before being held by the retainer holder 50, the retainer 41 is only supported by the spring 33, and the relative position of the retainer 41 to the rotating shaft 1 is unstable. When the retainer holder 50 comes into contact with the retainer 41, the retainer 41 is guided by the tapered surface 54 of the retainer holder 50 and fits into the peripheral wall 52 of the retainer holder 50.

In this way, even when the retainer 41 is not aligned with the retainer holder 50, the tapered surface 54 of the retainer holder 50 guides the retainer 41 into the retainer holder 50, and the retainer 41 is fitted into the peripheral wall 52 of the retainer holder 50, and the retainer 41 is held by the peripheral wall 52 and bottom wall 53 of the retainer holder 50. The inner diameter of the peripheral wall 52 of the retainer holder 50 is slightly larger than the outer diameter of the retainer 41, and the retainer holder 50 and the retainer 41 are substantially concentric. Therefore, the retainer 41 fitted into the peripheral wall 52 of the retainer holder 50 is concentric with the rotating shaft 1.

As shown in FIG. 7, while the retainer 41 is held by the retainer holder 50, the impeller 2, retainer holder 50, and retainer 41 are moved further toward the rotating ring 31 of the mechanical seal 20 until the retainer 41 passes over the step 1a of the rotating shaft 1. Because the retainer 41 is held by the retainer holder 50, the position of the retainer 41 is stable and the retainer 41 does not come into contact with the step 1a of the rotating shaft 1. Therefore, the impeller 2, retainer holder 50, and retainer 41 can move smoothly toward the rotating ring 31 of the mechanical seal 20.

Then, as shown in FIG. 8, the impeller 2 is fixed to the end of the rotating shaft 1 by the screw 11. A first seal 66 is sandwiched between the head of the screw 11 and the impeller 2.

In the above-described embodiment, when the pump P is assembled, the retainer 41 is held by the retainer holder 50, and the position of the retainer 41 is fixed by the retainer holder 50. Therefore, the retainer 41 does not come into contact with the step portion 1a of the rotating shaft 1, and the retainer 41 can move integrally with the retainer holder 50 toward the rotating ring 31 of the mechanical seal 20.

The above-described embodiments have been described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention pertains to practice the present invention. Various modifications of the above-described embodiments would naturally be possible for a person skilled in the art, and the technical ideas of the present invention may also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical ideas defined by the scope of the claims.

The present invention relates to a pump for liquids, and is particularly applicable to a pump having a mechanical seal disposed on a rotating shaft.

Reference Signs List P Pump M Motor 1 Rotating shaft 1a Step 2 Impeller 3 Main shaft 4 Shaft sleeve 10 Pump casing 11 Screw 14 Suction port 15 Discharge port 20 Mechanical seal 25 Main plate 26 Side plate 27 Blade 28 Boss portion 31 Rotating ring 32 Stationary ring 33 Spring 41 Retainer 50 Retainer holder 52 Circumferential wall 53 Bottom wall 54 Tapered surface 60 Shaft insertion hole 61 Fastening hole 62 Sleeve insertion hole 66 First seal 67 Second seal 71 End wall 72 Cylindrical wall

Claims

A rotation axis;
An impeller fixed to the rotating shaft;
a mechanical seal disposed to surround the rotating shaft;
a spring-supported retainer that presses a rotating ring of the mechanical seal against a stationary ring;
A retainer holder is attached to a rear side of the impeller,
the retainer holder has a peripheral wall into which the retainer is fitted, and a bottom wall extending radially inward from the peripheral wall,
The peripheral wall protrudes from the bottom wall toward the mechanical seal,
The peripheral wall has a tapered surface formed on its edge, the tapered surface having a truncated cone shape in which the inner diameter of the peripheral wall increases with distance from the bottom wall.
The pump of claim 1, wherein the retainer holder is concentric with the impeller and the rotating shaft.
the retainer has an end wall that contacts an end of the spring, and a cylindrical wall that protrudes from the end wall toward the rotating ring of the mechanical seal,
The pump of claim 1 , wherein an inner surface of the peripheral wall of the retainer holder is in contact with an outer surface of the cylindrical wall of the retainer.
The pump of claim 1, wherein the rotating shaft has a step on its outer circumferential surface, and the retainer is positioned between the step and the rotating ring of the mechanical seal.
The rotating shaft has a main shaft and a cylindrical shaft sleeve attached to an outer circumferential surface of the main shaft,
The rotating ring and the stationary ring of the mechanical seal surround an outer circumferential surface of the shaft sleeve,
5. The pump according to claim 4, wherein the step of the rotating shaft is formed from an end surface of the shaft sleeve.
The pump of claim 5, wherein the retainer holder is attached to a boss portion of the impeller.
A screw for fixing the impeller to an end of the rotating shaft;
a first seal that seals a gap between the impeller and the screw;
The pump according to claim 6 , further comprising a second seal that seals a gap between an inner peripheral surface of the boss portion of the impeller and an outer peripheral surface of the shaft sleeve.
The impeller and the retainer holder attached to the rear side of the impeller are moved along the rotation shaft toward the mechanical seal;
a retainer held by a spring that presses a rotating ring of the mechanical seal against a stationary ring is held by a bottom wall and a peripheral wall of the retainer holder;
With the retainer held by the retainer holder, further moving the impeller, the retainer holder, and the retainer along the rotation shaft toward the rotating ring of the mechanical seal;
Fixing the impeller to an end of the rotating shaft by a screw;
A method for assembling a pump, wherein the peripheral wall has a tapered surface formed on its edge, and the tapered surface has a truncated cone shape in which the inner diameter of the peripheral wall increases with distance from the bottom wall.