JP2011157897A - Centrifugal pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal pump requiring no shaft seal mechanism and free from leakage. <P>SOLUTION: A sealless-type centrifugal pump 1 includes a casing 10 forming a pump chamber 12 with an inflow port 11 and an outflow port for liquid, an impeller 30 disposed inside the pump chamber 12 and rotatably supported by a pivot bearing 20, and a magnetic coupling device 40 rotatively driving a permanent magnet 41 built in the impeller 30 through a partition. The impeller 30 supported in the direction of the rotation axis with respect to the casing 10 is driven by the magnetic coupling device 40, and pressure is applied to the liquid introduced from the direction of the rotation axis through the inflow port 11 to send the liquid through the outflow port in the radial direction. The magnetic coupling device 40 is disposed on a line inclined from an impeller rotating surface to an inflow port 11 side toward the center of the rotation axis, and a through-hole 33 in the direction of the rotation axis is formed at the center of rotation of the impeller 30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a centrifugal pump that applies pressure to a liquid by driving an impeller by magnetic coupling, and more particularly to a centrifugal pump that is suitable for a liquid such as a chemical liquid containing fine particles or a liquid such as a chemical liquid that is easily fixed.

Conventionally, a general pump has a shaft seal mechanism (shaft seal device) in order to prevent fluid in the pump chamber from leaking out from the shaft portion and inhaling air and the like from the outside. have. As the shaft seal mechanism, a gland packing, a labyrinth, a mechanical seal, and the like have been put into practical use, and are selected according to the operating environment and cost of the pump.
Among the above-described pumps, there is a centrifugal pump, which is configured to apply pressure energy or velocity energy in a radial direction to the fluid by centrifugal force by rotating an impeller within the casing.

Among the centrifugal pumps described above, there is a centrifugal pump that stabilizes and rotates the pump rotor by the permanent magnet acting in the radial direction on the ferromagnetic range of the pump rotor. (For example, see Patent Document 1)
There is also known an artificial heart centrifugal pump in which a permanent magnet is provided on a shaft portion of an impeller and the impeller is rotated by a driving device that generates a rotating magnetic field provided on the casing side. In this case, the impeller is supported by a pivot bearing, and it is disclosed that materials having different hardnesses such as a combination of ceramics and ultrahigh molecular weight polyethylene are selected as the material of the pivot shaft and the pivot receiver. Yes. (For example, see Patent Document 2)

Japanese Patent No. 2869886 JP 2002-349482 A

By the way, the centrifugal pump provided with the shaft seal mechanism has problems such as leakage from shaft seal components, generation of wear and friction, and limitation of heat resistant temperature and pressure resistance. For this reason, it is desired to develop a centrifugal pump that does not require a shaft seal mechanism and that does not leak.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a centrifugal pump that does not require a shaft seal mechanism and has no leakage. In particular, an object of the present invention is to provide a centrifugal pump that is suitable for a liquid such as a chemical liquid containing fine particles or a liquid such as a chemical liquid that is easily fixed, and that can be easily downsized.

In order to solve the above problems, the present invention employs the following means.
A centrifugal pump according to the present invention includes a casing forming a pump chamber having a liquid inlet and an outlet, an impeller disposed inside the pump chamber and rotatably supported by a pivot bearing, A magnetic coupling device that rotates a permanent magnet built in the impeller through a partition wall, and drives the impeller supported in the rotation axis direction with respect to the casing by the magnetic coupling device; In the sealless centrifugal pump configured to apply pressure to the liquid introduced from the rotation axis direction through the inlet and feed the liquid radially from the outlet, the pivot bearing is configured to rotate the impeller. The magnetic coupling comprising: a pivot shaft positioned at the shaft center; and a two-point support bearing portion for supporting the pivot shaft from both sides on the axial center line of the inlet. Is disposed on a line inclined toward the inlet from the impeller rotation surface toward the rotation axis center, and a through-hole in the rotation axis direction is formed at the rotation center of the impeller. To do.

  According to such a centrifugal pump of the present invention, the pivot bearing includes a pivot shaft that is positioned at the center of the rotating shaft of the impeller, and a two-point support bearing that supports the pivot shaft from both sides on the axial center line of the inlet. The magnetic coupling device is disposed on a line inclined toward the inlet side from the impeller rotation surface toward the rotation axis center, and a through-hole in the rotation axis direction is formed at the rotation center of the impeller Therefore, in the rotational axis direction of the impeller, a symmetric secondary flow is formed on both surfaces of the impeller, so that the axial thrust force can be balanced and the load on the pivot bearing can be reduced.

  In the above invention, the pivot bearing is preferably such that at least a part of the bibot shaft protrudes from the impeller to the inlet side, whereby the pivot bearing installed on the inlet side having a high flow velocity is , It is cooled efficiently by the fluid introduced from the inlet.

According to the present invention described above, the magnetic coupling device is arranged on a line inclined toward the inflow port toward the center of the rotation axis, and the impeller is stably supported by the pivot bearing of the two-point support, and the rotation center of the impeller Since the through-hole in the rotation axis direction is formed on the both sides of the impeller, a secondary flow symmetrical to both surfaces in the rotation axis direction is formed on both surfaces of the impeller. For this reason, since the axial thrust force acting on the impeller and the pivot shaft is balanced in the direction of the rotation axis, the load acting on the stable two-point support pivot bearing is reduced, and there is no leakage without using the shaft seal mechanism. A small centrifugal pump can be easily provided.
In addition, a centrifugal pump driven by a magnetic coupling device and having no shaft seal mechanism has a structure in which fine particles in the liquid are difficult to break and a structure in which the liquid is hard to stick. The pump is suitable for liquids such as chemicals.

It is a figure which shows one Embodiment of the centrifugal pump which concerns on this invention, (a) is a longitudinal cross-sectional view (cross-sectional view of a rotating shaft direction), (b) is AA sectional drawing of (a). It is a figure which expands and shows the pivot bearing of FIG. It is explanatory drawing of the secondary force symmetrical to the thrust force which acts on a pivot shaft, and the upper and lower sides of an impeller.

Hereinafter, an embodiment of a centrifugal pump according to the present invention will be described with reference to the drawings.
A centrifugal pump 1 according to the embodiment shown in FIG. 1 includes a casing 10 forming a pump chamber 12 having a liquid inlet 11 and an outlet (not shown), and a pivot bearing 20 disposed in the pump chamber 12. And a magnetic coupling device 40 for rotating the permanent magnet 41 built in the impeller 30 through the partition wall of the casing 10.

  The casing 10 forms a pump chamber 12 that introduces liquid from an inflow port 11 that is coaxial with the rotational axis center of the impeller 30 and pressurizes by rotation of the impeller 30. The liquid pressurized in the pump chamber 12 is sent out in the radial direction of the impeller 30 from an outlet provided in the pump chamber 12. That is, the impeller 30 rotates in the pump chamber 12 of the casing 10 supported by the pivot bearing 20 serving as a rotation axis that coincides with the axial center line of the inflow port 11. In the illustrated configuration example, the impeller 30 rotates on a horizontal plane, and the inflow port 11 is disposed on a vertical line orthogonal to the rotation plane (horizontal plane) of the impeller 30 and above the impeller rotation plane. .

The pivot bearing 20 includes a pivot shaft 21 positioned at the center of the rotation shaft of the impeller 30, and two-point bearings 22 and 23 that support the pivot shaft 21 from both sides on the axial center line of the inlet 11. . The pair of bearing portions 22 and 23 are both fixedly supported on the casing 10 side.
The pivot shaft 21 fixedly supported on the impeller 30 via the support member 24 is made of a material having excellent low friction performance, water lubrication performance and corrosion resistance, such as alumina ceramics and carbonitrided titanium nitride alloy. ing.
On the other hand, the bearings 22 and 23 fixedly supported on the casing 10 side are made of, for example, a fluoropolymer such as ultrahigh molecular weight polyethylene or polytetrafluoroethylene (PTFE), a polyether ether ketone (PEEK) resin material, or the like. A material excellent in low friction and wear resistance is applied.

Further, the pivot bearing 20 has a structure in which the bearing portions 22 and 23 having a concave curved surface rotatably support the pivot shaft 21 having a convex curved surface having substantially the same shape. That is, in the illustrated configuration example, on the rotation axis of the impeller 30, the bearing portion 22 supports the lower surface of the pivot shaft 21, and the bearing portion 23 supports the upper surface of the pivot shaft 21, thereby providing stable two-point support. The pivot shaft 20 has a structure. In this case, one bearing portion 22 is fixedly supported by a bearing support portion 13 provided in the casing 10, and the other bearing portion 23 is fixedly supported by the inner peripheral surface of the inflow port 11 via a support member 23 a. .
The bearing support portion 13 is a portion in which the inner surface of the casing 10 protrudes toward the inlet 11 on the rotation axis of the impeller 30, and the through-hole 33 in the rotation axis direction formed at the rotation center of the impeller 30 is substantially omitted. It is provided to penetrate. The bearing support portion 13 in this case changes direction while drawing a smooth curve from the rotation axis direction (inlet 11) toward the radial direction of the impeller 32.

The impeller 30 is obtained by attaching a plurality of blade portions 32 to an impeller body 31. In the illustrated configuration example, a plurality of blade portions 32 are radially attached to the inlet side end surface of the impeller body 31 having a substantially hollow cylindrical shape. A plurality of support members 24 that connect the pivot shaft 21 and the impeller 30 are radially provided in the through-hole 33 provided in the shaft center portion of the impeller 30. In the illustrated configuration example, three support members 24 are provided at a pitch of approximately 120 degrees, and three through holes 33 are formed between the support members 24. However, the present invention is not limited to this. Absent.
The impeller 30 configured as described above is supported in the rotation axis direction with respect to the casing 10 via the pivot bearing 20 and can be rotated around the rotation axis by a driving force of a magnetic coupling device 40 described later. It is supported by.

The magnetic coupling device 40 includes a permanent magnet 41 built in the impeller 30 and a drive-side magnet 42 that rotates the outer periphery of the casing 10. As a magnet suitable for the permanent magnet 41 and the drive magnet 42, for example, a neodymium magnet, which is said to be the strongest, is effective for downsizing the centrifugal pump 1.
In the illustrated configuration example, a plurality of permanent magnets 41 are embedded in the impeller body 31 at an equal pitch in the circumferential direction.
A plurality of drive magnets 42 are fixedly installed in the circumferential direction at an equal pitch with respect to a rotor 44 that rotates integrally with a rotary shaft 43 connected to a drive source (not shown).

  The magnetic coupling device 40 in the present embodiment is disposed on a line that is inclined from the impeller rotation surface toward the inlet 11 toward the rotation axis center of the impeller 30. That is, the magnetic coupling device 40 is inclined from the rotation surface of the impeller 30, and the magnetic forces of the permanent magnet 41 and the drive magnet 42 attract each other on a line inclined from the impeller rotation surface to the inlet 11 side. Acts on direction.

  The centrifugal pump 1 configured as described above causes the impeller 30 to attract the permanent magnet 41 to the drive magnet 42 by driving the magnetic coupling device 40, that is, by rotating the drive magnet 42 together with the rotor 44. To go around. For this reason, the magnetic coupling 40 can rotate the impeller 30 through the partition wall of the casing 10, and as a result, the liquid introduced from the direction of the rotation axis through the inflow port 11 is pressurized by the impeller 30. It is given and flows out from the outlet in the radial direction.

In the centrifugal pump 1 configured in this way, the pivot bearing 20 supports the pivot shaft 21 positioned at the center of the rotating shaft of the impeller 30 and the two-point support for supporting the pivot shaft 21 from both sides on the axial center line of the inlet 11. The magnetic coupling device 40 is disposed on a line inclined toward the inflow port 11 from the impeller rotation surface toward the rotation axis center, and rotates about the rotation center of the impeller 30. Since the through-hole 33 in the axial direction is formed, in the rotational axis direction of the impeller 30, for example, as shown in FIG. 3, a secondary flow that is symmetrical on both surfaces of the impeller 30 (see arrow W in the figure). Is formed.
In this case, both surfaces of the impeller 30 are upper and lower surfaces facing the inner surface of the pump chamber 12 in the rotation axis direction, and are also surfaces that form an air gap (gap) of the impeller 30.

  By providing the above-described through-hole 33, a vertically symmetric secondary flow toward the rotation axis through the air gap is formed on both the upper and lower surfaces of the impeller 30. The load on the pivot bearing 20 can be reduced by balancing the axial thrust force Fs that acts. At this time, since the support member 24 has a shape that smoothly changes direction, the support member 24 further promotes the formation of a secondary flow that is vertically symmetric.

  Further, the pivot bearing 20 of the centrifugal pump 1 described above is desirably arranged at a position where at least a part of the bibot shaft 21 protrudes from the impeller 30 toward the inlet 11. The position of the pump chamber 12 that protrudes from the impeller 30 toward the inlet 11 is a region that becomes a flow path through which the main flow of the liquid introduced from the inlet 11 into the pump chamber 12 always passes. Is also a high area.

For this reason, the pivot bearing 20 disposed in the region where the flow rate of the liquid introduced into the pump chamber 12 is high promotes the cooling effect by contact with the liquid whose pressure is increased by the centrifugal pump 1. The frictional heat generated in is absorbed efficiently and the temperature rise can be suppressed. That is, the pivot bearing 20 installed on the side of the inlet 11 having a high flow velocity is efficiently cooled by the flow of fluid introduced from the inlet 11, so that the temperature rise of the pivot bearing 20 is suppressed, The durability of the pivot bearing 20 and the centrifugal pump 1 can be improved.
As for the position of the bibot bearing 20, considering only the cooling effect, the entire pivot bearing 20 may be arranged in a region where the liquid flow velocity is high, that is, in a region higher than the impeller 30 (close to the inlet 11). For example, a practical optimum position may be selected in consideration of conditions for stable rotation support of the impeller 30 and the like.

As described above, according to the centrifugal pump 1 of the above-described embodiment, the magnetic coupling device 40 is arranged on a line inclined toward the inflow port toward the rotation axis center, and the impeller 30 is supported by the pivot bearing 20 that is supported at two points. Since the through-hole 33 in the rotation axis direction is formed at the rotation center of the impeller 30, the axial thrust force acting on the impeller 30 and the pivot shaft 20 is balanced in the rotation axis direction, that is, up and down The thrust forces in the direction cancel each other, so that almost no action occurs. As a result, the load acting on the stable two-point supported pivot bearing 20 can be reduced, and the small centrifugal pump 1 having no leakage can be easily provided without using the shaft seal mechanism.
Further, if the centrifugal pump 1 without the shaft seal mechanism driven by the magnetic coupling device 40 is used, there is no shaft seal mechanism that causes damage to the fine particles in the liquid or causes the liquid to be fixed. It becomes a suitable pump for increasing the pressure of a liquid such as a liquid (mixed fluid) or a liquid such as a chemical liquid that is easily fixed.

Further, the blade portion 32 of the impeller 30 preferably has a double volute shape in order to reduce the radial load on the pivot bearing 20. This is because, when the blade portion 32 of the single volute is used, the radial load decreases near the design point, but when the centrifugal pump 1 is operated outside the design point, the radial load increases.
The volute shape of the pump chamber 12 is desirably a closed impeller in order to reduce the radial load on the pivot bearing 20.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.

DESCRIPTION OF SYMBOLS 1 Centrifugal pump 10 Casing 11 Inlet 12 Pump chamber 20 Pivot bearing 21 Pivot shaft 22, 23 Bearing part 30 Impeller 33 Through-hole 40 Magnetic coupling apparatus 41 Permanent magnet 42 Drive magnet

Claims (2)

A casing forming a pump chamber having a liquid inlet and outlet, an impeller disposed inside the pump chamber and rotatably supported by a pivot bearing, and a permanent built in the impeller A magnetic coupling device that rotationally drives the magnet through the partition wall, the impeller supported in the rotational axis direction with respect to the casing is driven by the magnetic coupling device, and the rotational axis line is provided via the inflow port. In a sealless centrifugal pump configured to apply pressure to a liquid introduced from a direction and feed the liquid radially from the outlet,
The pivot bearing includes a pivot shaft positioned at the center of the rotating shaft of the impeller, and a two-point support bearing portion that supports the pivot shaft from both sides on the axial center line of the inlet,
The magnetic coupling device is disposed on a line inclined from the impeller rotation surface toward the rotation axis toward the inlet, and
A centrifugal pump characterized in that a through-hole in the rotation axis direction is formed at the rotation center of the impeller. 2. The centrifugal pump according to claim 1, wherein at least a part of the bibot shaft of the pivot bearing protrudes from the impeller toward the inlet.

Images