TITLE

MAGNETICALLY ENGAGED PUMP

BACKGROUND OF THE INVENTION

The field of the present invention is pumps which are magnetically coupled to a power source.

U.S. Patent No. 7,137,793 to Shafer et al., U.S. Patent No. 7,183,683 to Shafer et al. and U.S. Patent No. 7,549,205 to Shafer are directed to magnetically engaged pumps, the disclosures of which are incorporated herein by reference. SUMMARY OF THE INVENTION

The present invention is directed to pumps having a pump housing. A shaft is fixed within the pump housing. A pump rotor is rotatably mounted about the fixed shaft. A magnetic engagement, including a magnetic drive assembly, a magnetic driven assembly associated with the pump rotor and a canister between the drive assembly and the driven assembly provides a sealless engagement between the drive assembly and the pump rotor. The pump further includes a rotatable carrier about the stationary shaft. This carrier includes a radial attachment flange fixable to the driven magnetic assembly. The rotatable carrier is axially removable through the pump rotor. The carrier includes a plain bearing position to receive a bushing. The arrangement of the rotatable carrier thus allows replacement of the bearing support without requiring the pump to be taken out of its mounting or the magnetic coupling assembly to be disrupted. The carrier may also include thrust bushing positions which can face a shoulder on the fixed shaft and face the end of the canister.

In the preferred embodiments, multiple categories of pumps are disclosed.

Further, selective integrations of components are disclosed in the embodiments. It is intended and here taught that the independent variations in each embodiment may be employed in the other embodiment with equal applicability. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side view of a magnetically engaged gear pump shown in cross section through the principal axis of the pump;

Figure 2 is an isometric view also in cross section through the principal axis of the magnetically engaged gear pump illustrating the pump rotor, the rotatable driven magnetic assembly and the rotatable carrier assembly;

Figure 3 is an isometric cross section taken through the principal axis of the pump of the three assemblies of Figure 2 in exploded assembly;

Figure 4 a front view of a magnetically engaged centrifugal pump;

Figure 5 is a side view of the magnetically engaged centrifugal pump shown in cross section through the principal axis of the pump; and

Figure 6 is an isometric cross section taken through the principal axis of the magnetically engaged centrifugal pump of the pump rotor, the rotatable driven magnetic assembly and the rotatable carrier assembly of Figure 5 in exploded assembly.

Reference numbers in the Figures correspond between embodiments where the elements illustrated are the same.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning in detail to the Figures, a gear pump with a magnetic engagement is disclosed in the preferred embodiment of Figures 1 through 3. The gear pump includes a pump housing, generally designated 10, defined by a first housing portion 12 and a second housing portion 14. The portions are bolted together. The pump housing 1 0 further includes a bearing cap 16 closing a first end of the pump housing 10 by being bolted to the first housing portion 12 and a pump shaft support 1 8 closing a second end of the pump housing 10 and bolted to the second housing portion 14. The bearing cap 16 includes a power coupling through a drive shaft 20 mounted in bearings 22. The drive shaft 20 is capable of being keyed to a rotational source of power (not shown). The pump shaft support 18 includes a cap 24. The fluid inlet (not shown) and a fluid outlet 26 conventionally extend into the pump housing 1 0.

A rotatable magnetic drive assembly includes a cup-shaped drive member 28. Magnets 30 are held in an annular arrangement about the axial recess defined by the cup-shaped member 28. A hub 32 on the member 28 is mounted to the drive shaft 20 and keyed to rotate therewith. The cup-shaped portion is cantilevered from the hub 32 within the pump housing 10 forming a cylindrical surround for the magnetic coupling.

A rotatable driven magnetic assembly includes a generally cylindrical magnet mount 34 with magnets 36 about the periphery to define a magnetic portion physically disposed substantially in alignment with the magnets 30 for magnetic alignment to enable a magnetic coupling. With the rotatable magnetic drive assembly and the rotatable driven magnetic assembly, the magnetic coupling is conventionally arranged.

A complex stationary mounting shaft 38 fixed to the pump housing at the pump shaft support 1 8 defines two cylindrical shafts 40, 42 with axes axially and laterally displaced. A radial mounting flange 44 is located between the two shafts 40, 42. The mounting shaft 38 is mounted to the shaft support 18 by fasteners 46 to the mounting flange 44 and by a stub end 48 on the cylindrical shaft 42 positioned within a cavity 50 in the shaft support 1 8. This arrangement structurally cantilevers the shaft 40 into the magnetic coupling. The mounting flange 44 further defines a shoulder at one end of the cylindrical shaft 40 facing the drive end of the gear pump.

To divide the sealless magnetic coupling defined by the magnets 30, 36, a cylindrical canister extends between the magnets 30, 36 within the axial recess of the cup-shaped drive member 28. The canister is thin walled between the magnets 30, 36 and is of non-ferromagnetic material to avoid interference with the magnetic coupling. The canister 52 is fixed to the pump housing 10 by a radial mounting flange 54 to effect a sealing engagement.

The mounting flange 54 is conveniently fixed between the first and second housing portions 12, 14. At the other end of the canister 52, a canister cap 56 closes the canister 52. The canister cap 56 receives the end of the cylindrical shaft 40, which helps to position the thin wall of the canister 52. The canister cap 56 also defines a shoulder facing the pump shaft support second end of the pump housing 10. A center knob on the canister cap 56 extends to near the pump housing. This will prevent the canister cap 56 from excessive deflection if the defined shoulder is pushed too far. A pump rotor 58 is fixable to the magnet mount 34 of the rotatable driven magnet assembly in the gear pump. The pump rotor 58 is principally positioned within the first housing portion 12 of the pump housing 1 0 and includes an annular gear with teeth 60 as best seen in Figures 2 and 3. An inwardly extending radial mounting flange 62 on the pump rotor 58 abuts against the near end of the magnet mount 34 of the rotatable driven magnet assembly. A gear wheel 64 is rotatably mounted about the laterally displaced cylindrical shaft 42 about a bushing 66. The rotatable gear wheel 64 is meshed with the teeth 60 of the annular gear of the pump rotor 58. This gear then defines a gear pump in communication with the fluid inlet and fluid outlet 26 of the pump.

A rotatable carrier 68 is mounted about the cylindrical shaft 40. The magnet mount 34 includes a concentric cylindrical cavity extending fully therethrough to receive the rotatable carrier 68. The magnet mount 34 and the rotatable carrier 68 are shown to define an annular cavity therebetween to reduce material and weight. O-rings may be placed at the contact surfaces between the two components, as seen in Figure 3, to isolate the annular cavity from working fluids.

A radial attachment flange 70 is located at the end of the rotatable carrier 68 adjacent the pump rotor 58. This radial attachment flange 70 is outwardly of the inwardly extending mounting flange 62 of the pump rotor 58. Three fasteners 72 equiangularly spaced extend through mounting holes in the radial attachment flange 70, the inwardly extending radial mounting flange 62 and the end of the magnet mount 34 to retain these three elements together such that they are able to rotate as an assembly about the cylindrical shaft 40.

The rotatable carrier 68 includes a bore 74 therethrough to receive the shaft 40. In the gear pump, the bore 74 includes two plain bearing positions 76, 78 to retain bushings 80, 82 for concentrically mounting the magnet mount 34 and the pump rotor 58 about the shaft 40. The ends of the rotatable carrier 68 about the bore 74 include thrust bearing positions 84, 86 to retain thrust bushings 88, 90 to face the shoulder on the mounting flange 44 of the shaft 40 and the canister cap 56, respectively.

The rotatable carrier 68 has the attribute of providing a mechanism for the positive retention and arrangement of the bushings 80, 82, 88, 90. Further, the entire rotatable subassembly, as illustrated in Figures 2 and 3, can be accessed without removing the pump from its mounting and plumbing. By removal of the pump shaft support 18, the mounting shaft 38 can be withdrawn with the gear wheel 64. This exposes the fasteners 72. Optionally, the entire assembly as illustrated in Figures 2 and 3 can be withdrawn with the fasteners 72 in place. More importantly, the fasteners 72 can be removed, allowing the rotatable carrier 68 to be withdrawn while leaving the remainder of the pump including the rotor 58 and the magnet mount 34 in place. All bushings in the pump and the rotatable carrier 68 can be inspected and replaced. The principal bushings of the close tolerance magnetic coupling can be received as a unit and installed as such.

A centrifugal pump with a magnetic engagement is disclosed in the preferred embodiment of Figures 4 through 6. The pump includes a pump housing, generally designated 10, defined by a first housing portion 12 and a second housing portion 100 varying from the housing portion 14 of the gear pump in conventional ways to accommodate a centrifugal pump mechanism and flow. The portions 1 2 and 100 are bolted together. The pump housing 10 further includes a bearing cap 16 closing a first end of the pump housing 10 by being bolted to the first housing portion 12 and a pump shaft support 102 at a second end of the pump housing 10 and bolted to the second housing portion 100. The first end of the housing 10 remains as in the gear pump with the bearing cap 16, the drive shaft 20 and the bearings 22. The pump shaft support 102 includes a fluid inlet 1 04 to the pump. A fluid outlet 106 conventionally extend from the pump housing 10. A stationary mounting shaft 108 is fixed to the pump housing at the pump shaft support 1 02. This arrangement structurally cantilevers the shaft 108 through the pump rotor into the magnetic coupling. The stationary mounting shaft 108 also engages the canister cap 56 as in the gear pump.

The magnetic coupling in the centrifugal pump is identical to that of the gear pump. This includes the rotatable magnetic drive assembly, the rotatable driven magnetic assembly and the cylindrical canister. A magnet mount 1 1 2 of the rotatable driven magnet assembly, shown in the gear pump to be a separate cylindrical element 34, is, however, integrally formed with a pump rotor 1 14 in the centrifugal pump of Figures 4 through 6 as an extended skirt thereof. The magnet mount 1 12 includes an inwardly extending shoulder 1 1 6 facing the pump rotor 1 14. This integral configuration applies equally well to the gear pump preferred embodiment.

The pump rotor portion 1 14 of this integrated rotational element extending from the magnet mount 1 12 is principally positioned within the first housing portion 12 of the pump housing 10 and includes a shrouded annular impeller wheel 1 1 8 as best seen in Figures 5 and 6 to operate as a centrifugal pump. An inner impeller wheel 122 is mounted to the integrated rotational element. The inner impeller wheel 122 has a diameter which allows it to pass through the central opening in the front shroud 124 fixed to or integral with the annular impeller wheel 1 1 8. The annular impeller wheel 1 1 8 and the inner impeller wheel 122 include vanes that are aligned such that the two operate as a unit when assembled to have continuity of flow through the impeller assembly.

A rotatable carrier 1 26 having a central bore 128 is mounted about the stationary mounting shaft 108. The magnet mount 1 1 2 in turn includes a concentric cylindrical cavity extending fully therethrough to receive the rotatable carrier 126. The magnet mount 1 1 2 and the rotatable carrier 1 26 are shown to define an annular cavity therebetween to reduce material and weight. O-rings may be placed at the contact surfaces between the two components, as seen in Figure 6, to isolate the annular cavity from working fluids.

A radial attachment flange 130 is located at the end of the rotatable carrier

126. This radial attachment flange 1 30 extends to mate against the inwardly extending shoulder 1 1 6. The inner impeller wheel 1 22 of the impeller wheel 1 18 mates against the other side of the radial annular flange. The radial attachment flange 1 30 has a diameter no larger than the diameter of the inner impeller wheel 122 of the impeller wheel 1 18, allowing it to pass through the impeller wheel 1 18 and the central opening in the front shroud 124. Three fasteners 132 equiangularly spaced extend through mounting holes in the inner impeller wheel 122, the radial attachment flange 130 and into the inwardly extending shoulder 1 16 to retain these three elements together. By removing the fasteners 1 32, the inner impeller wheel 122 of the impeller wheel 1 18 and the rotatable carrier 1 26 can be withdrawn from the pump housing 10.

The rotatable carrier 1 26 in the second embodiment of Figures 4 through 6 includes two plain bearing positions 134, 138 in the central bore 128. In this centrifugal pump, bushings 136, 140 are integrally formed with the rotatable carrier 1 26 at the plain bearing positions 1 34, 138. These bushings 1 36, 140 rotationally and concentrically mount the magnet mount 1 12 and the pump rotor 1 14 about the stationary mounting shaft 108. The end of the rotatable carrier 126 about the bore 128 toward the driving end of the centrifugal pump includes a thrust bearing position 142. Also in the centrifugal pump, a thrust bushing 144 is integrally formed with the rotatable carrier 126 at the thrust bearing position 142. This thrust bushing 144 faces the canister cap 56.

As true of the gear pump, the rotatable carrier 126 has the attribute of providing a mechanism for the positive retention and arrangement of the bushings 136, 140, 144. Further, the entire rotatable subassembly, as illustrated in Figures 5 and 6, can be accessed without disassembly of the magnetic coupling or removal of the pump rotor 1 14 from the pump and in turn the pump from its mounting. By removal of the pump shaft support 1 02, the fasteners 132 are exposed. The fasteners 132 can be removed, allowing the rotatable carrier 126 to be withdrawn while leaving the remainder of the pump including the rotor 1 14 and the magnet mount 1 12 in place.