US 5,961,301 A · Magnetic-drive assembly for a multistage centrifugal pump

Abstract

The magnetic-drive assembly has an axial bearing which is strategically located to minimize compressive forces on a primary shaft. The axial bearing functions both as an ordinary thrust bearing and an inefficient impeller for circulating fluid internally within the magnetic-drive assembly. The axial bearing circulates lubricating fluid to a radial bearing to promote bearing longevity. The magnetic-drive assembly has a shaft adjustment mechanism for adjusting the axial orientation of a primary shaft and impellers with respect to a housing. The shaft adjustment mechanism retains its fixed axial orientation despite exposure to vibration and shock produced by the pump.

Drawings

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Drawings

Claims53

Dependent claims

A magnetic-drive assembly for a multi-stage, centrifugal pump having a primary shaft, the assembly comprising:

a housing having a bearing support;
a containment structure associated with the housing;
a first rotor located on a wet side of the containment structure, the first rotor coupled to the primary shaft for rotation with the primary shaft;
a second rotor located on a dry side of the containment structure, the second rotor magnetically coupled to the first rotor;
a bushing supported by the bearing support, the bushing being associated with the primary shaft;
a thrust ring disposed between the first rotor and the bearing support;
axial adjustment means for adjusting an axial position of the primary shaft with respect to the housing, the axial adjustment means redundantly securing the orientation of an adjustment nut upon the primary shaft.

4 more elements

A magnetic-drive assembly for a multi-stage, centrifugal pump having a primary shaft, the magnetic-drive assembly comprising:

a housing having a bearing support,
a containment structure cooperating with the housing to confine any pumped fluid to a wet side of the containment structure;
a first rotor located on the wet side of the containment structure, the first rotor coupled to the primary shaft for rotation with the primary shaft, the first rotor having magnets arranged about its periphery, the first rotor having a sleeve-like, cylindrical projection extending axially from the first rotor, the cylindrical projection connected to the primary shaft, the first rotor having bores extending axially into the first rotor;
a second rotor located on a dry side of the containment structure, the second rotor magnetically coupled to the first rotor, the second rotor having magnets;
a bushing supported by the bearing support, the bushing being associated with the primary shaft;
a thrust ring interposed between a bearing face of the first rotor and the bearing support;
an adjustment nut located on said primary shaft, the adjustment nut having holes extending axially through a face of the adjustment nut;
a primary retention fastener extending through one of said holes and into the first rotor.

5 more elements

A centrifugal multi-stage pump comprising:

a primary shaft;
a housing having a bearing support, the bearing support radially extending toward a pump interior, the housing having discharge chambers and intake chambers;
a containment structure associated with the housing, the housing cooperating with the containment structure to confine any pumped fluid to a wet side;
a first rotor located on the wet side of the containment structure, the first rotor coupled to the primary shaft for rotation with the primary shaft, the first rotor having an impeller-like face;
a second rotor located on a dry side of the containment structure, the second rotor magnetically coupled to the first rotor;
impellers located in the discharge chambers and coupled to the primary shaft, a majority of the impellers having their impeller intakes facing downward;
a radial bearing located within the housing, the radial bearing being associated with the primary shaft;
a thrust ring disposed between the first rotor and the bearing support, the thrust ring and the impeller-like face cooperating to handle downward axial forces, the thrust ring and impeller-like face placing primarily tensile forces on the shaft in response to the downward axial forces from the impellers;
and
axial adjustment means for adjusting and securing the axial position of the primary shaft with respect to the housing, the axial adjustment means redundantly securing the orientation of an adjustment nut upon the primary shaft.

7 more elements

A centrifugal multi-stage pump comprising:

a primary shaft;
a housing having a bearing support, the bearing support radially extending toward a pump interior, the housing having discharge chambers and intake chambers;
a containment structure cooperating with the housing to confine any pumped fluid to a wet side of the pump;
a first rotor located on the wet side of the containment structure, the first rotor coupled to the primary shaft for rotation with the primary shaft, the first rotor having an bearing face with alternating lands and grooves;
a second rotor located on a dry side of the containment structure, the second rotor magnetically coupled to the first rotor;
impellers located in the discharge chambers and coupled to the primary shaft, a majority of the impellers having their intakes facing downward;
a radial bearing located within the housing, the radial bearing being associated with the primary shaft and having a bushing;
a thrust ring disposed between the first rotor and the bearing support, the thrust ring and the bearing face cooperating to handle downward axial forces, the thrust ring and bearing face placing primarily tensile forces on the shaft in response to downward axial forces from the impellers;
and
axial adjustment means for adjusting the axial position of the primary shaft with respect to the housing, the axial adjustment means redundantly securing the orientation of an adjustment nut upon the primary shaft.

7 more elements

A method for adjusting an axial displacement of a primary shaft in a multi-stage centrifugal pump with respect to a housing of the multi-stage centrifugal pump, the housing containing impellers and associated discharge chambers;

the method comprising the steps of:
a) determining a desired axial position of the primary shaft of a multi-stage pump;
b) tightening an adjustment nut on the primary shaft enough to align the primary shaft in a desired axial direction;
c) aligning holes in the adjustment nut with retention bores in a first rotor by rotating the adjustment nut a minimal possible amount;
d) placing retention fasteners through the holes in the adjustment nut and into the retention bores;
and
e) tightening the retention fasteners within the retention bores.

4 more elements

Dependencies are inferred from the claim text.

Description8,658 words

Summary1,206 words

#The present invention relates generally to centrifugal pumps; more specifically to multi-stage centrifugal pumps with magnetic-drive assemblies.

#Multi-stage centrifugal pumps are often used where single-stage centrifugal pumps do not meet the output pressure or head requirements of the particular application. Most multi-stage centrifugal pumps presently use shaft seals to isolate the pumped fluid from the motor. For example, U.S. Pat. No. 5,445,494, entitled MULTI-STAGE CENTRIFUGAL PUMP WITH CANNED MAGNETIC BEARING and issued to Hanson, discloses a seal for isolating pumped fluid from the motor and magnetic bearings. Shaft seals may leak hazardous or caustic fluids, potentially endangering the safety of pump operators. Periodic inspections of seals are required to reduce unwanted emissions from pumps.

#Magnetic-drive, multi-stage pumps may be used to replace entire pumps with seals to reduce unwanted emissions. However, magnetic-drive assemblies cannot be coupled readily to multi-stage centrifugal pumps, designed for traditional seals, without first solving sundry engineering problems. Axial bearing design and axial shaft adjustment are some illustrative examples of engineering problems related to converting multi-stage pumps to magnetic-drive operation.

Brief description of the drawings16 figures

#FIG. 1A and FIG. 1B show a cross-sectional view of a multi-stage pump incorporating a first embodiment of the magnetic-drive assembly.

#FIG. 2 is an enlarged cross-sectional view of the magnetic-drive assembly shown in FIG. 1A and FIG. 1B.

#FIG. 3A illustrates an impeller-like face of the first rotor along reference line 3A--3A of FIG. 2.

Detailed description7,097 words

#FIG. 1A and FIG. 1B shows an illustrative example of a multi-stage pump 10. The multi-stage pump 10 includes a multi-stage impeller assembly 20 and a magnetic-drive assembly 40. A drive motor 80 is coupled to the multi-stage pump 10 through the magnetic-drive assembly 40.

#The multi-stage impeller assembly 20 includes an impeller housing 12, lower radial bearings 24, a primary shaft 14 and impellers 22. The impeller housing 12 contains discharge chambers 30 and intake chambers 38. Lower radial bearings 24 rotatably support the primary shaft 14 within the impeller housing 12. The impellers 22 are located within the discharge chambers 30. The impellers 22 are coupled to the primary shaft 14 so as to propel fluid from an inlet 34 to an outlet 36 when the primary shaft 14 is rotated.

#The interior of the impeller housing 12 is divided into discharge chambers 30 and intake chambers 38. The inlet 34 and an outlet 36 of the impeller housing 12 are located near the bottom of the multi-stage pump 10. The inlet 34 and the outlet 36 are optimally configured for in-line operation. The inlet 34 has an inlet volume 35 that fluidly or hydrodynamically communicates with an impeller 22 located in a first stage 98. The outlet 36 fluidly or hydrodynamically communicates with an impeller 22 located in a last stage 100. The impeller housing 12 may be made from multiple casing members for ease of manufacturing. For example, the impeller housing 12 in FIG. 1 has a first casing section 72 and a second casing section 74. The impeller housing 12 is associated with a radial bearing support 102 that supports the lower radial bearings 24.

Facts

Application

08/904,143Filed 31 Jul 1997

Granted

5 Oct 1999

Term ended

31 Jul 2017

Estimated · how

20 years from earliest known nonprovisional domestic filing. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination. Patent term adjustment is unavailable; no adjustment was added.

Classification7 codes

F04D 29/047
Bearings: hydrostatic; hydrodynamic
F04D 1/06
Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps: multi-stage pumps
F04D 13/026
A magnetic coupling: details of the bearings
F04D 29/0413
Axial thrust balancing: hydrostatic; hydrodynamic thrust bearings

Description8,658 words

Summary1,206 words

#The present invention relates generally to centrifugal pumps; more specifically to multi-stage centrifugal pumps with magnetic-drive assemblies.

Brief description of the drawings16 figures

#FIG. 1A and FIG. 1B show a cross-sectional view of a multi-stage pump incorporating a first embodiment of the magnetic-drive assembly.

#FIG. 2 is an enlarged cross-sectional view of the magnetic-drive assembly shown in FIG. 1A and FIG. 1B.

#FIG. 3A illustrates an impeller-like face of the first rotor along reference line 3A--3A of FIG. 2.

Detailed description7,097 words

Magnetic-drive assembly for a multistage centrifugal pump

Life of this patent

Magnetic-drive assembly for a multistage centrifugal pump

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims53

Description8,658 words

Drawings

Classification7 codes

Life of this patent

Description8,658 words