CN110462221B

CN110462221B - Centrifugal pump assembly with axial flux motor and method of assembling the same

Info

Publication number: CN110462221B
Application number: CN201880021654.9A
Authority: CN
Inventors: M·J·特纳; G·海因斯; M·蒂勒; J·J·克雷德勒
Original assignee: Regal Beloit Australia Pty Ltd; Regal Beloit America Inc
Current assignee: Regal Beloit Australia Pty Ltd; Regal Beloit America Inc
Priority date: 2017-01-27
Filing date: 2018-01-26
Publication date: 2022-04-29
Anticipated expiration: 2038-01-26
Also published as: WO2018140731A1; CN110462221A; EP3574220A1; EP3574220A4; AU2018213376A1

Abstract

A motor assembly includes a bearing assembly including a rotating component and at least one stationary component. The motor assembly also includes an impeller coupled to the rotating member. The impeller includes an inlet and an outlet and is configured to direct fluid between the inlet and the outlet. The motor assembly also includes a rotor assembly directly coupled to the impeller. A fluid flow passage is defined between the rotating component and the at least one stationary component. The flow passage includes a first end proximate the impeller outlet and a second end proximate the impeller inlet.

Description

Centrifugal pump assembly with axial flux motor and method of assembling the same

Cross Reference to Related Applications

The present application claims priority from U.S. patent application No.15/418,155 filed on day 27, month 1, 2017 and U.S. patent application No.15/418,171 filed on day 27, month 1, 2017, the entire disclosures of which are incorporated herein by reference in their entirety.

Technical Field

The field of the invention relates generally to centrifugal pump assemblies and more particularly to centrifugal pump assemblies including an axial flux motor coupled to an impeller.

Background

At least some known centrifugal pumps include an impeller for directing fluid through the pump. The impeller is coupled via a hydrostatic bearing to a shaft that is coupled to a rotor of the motor such that rotation of the rotor causes rotation of the bearing and the impeller. In at least some known electric motors, a separate pump is used to deliver the pressurized fluid flow required for operation of the hydrostatic bearings. The additional pump adds complexity and cost to the pump system, which may inhibit the use of hydrostatic bearings in cost-sensitive applications.

Furthermore, at least some known centrifugal pumps include hydrodynamic bearings. In designing a fluid dynamic bearing, a number of factors need to be considered. One of these is the ability of the bearing to hydrodynamically "lift" and separate the rotating bearing component from the stationary bearing component during operation. It is important that the bearings "lift up" to ensure proper operation. If the bearing is not "lifted", there will be large friction between the two bearing materials, resulting in large frictional torque resistance, drag torque resistance, and material wear. To ensure bearing lift, the bearings are designed such that the Pressure Velocity (PV) factor falls within a predetermined range. The PV factor is based on the speed of the rotating component and the coefficient of friction between the rotating and stationary bearing components. However, at least some known slew bearing components are flat discs, resulting in a speed differential between the inner and outer diameters of the disc. This speed difference results in a large range of PV factors, at least some of which may be outside the desired range. Operation of the fluid dynamic bearing outside of the desired PV factor range may result in inefficient operation of the pump assembly and/or reduced service life of the bearing components.

Disclosure of Invention

In one aspect, a motor assembly is provided. The motor assembly includes a bearing assembly including a rotating component and at least one stationary component. The motor assembly also includes an impeller coupled to the rotating member. The impeller includes an inlet and an outlet and is configured to direct fluid between the inlet and the outlet. The motor assembly also includes a rotor assembly directly coupled to the impeller. A fluid flow path is defined between the rotating component and the at least one stationary component. The flow passage includes a first end proximate the impeller outlet and a second end proximate the impeller inlet.

In another aspect, a pump assembly is provided. The pump assembly includes a pump housing and a motor housing coupled to the pump housing. The pump assembly also includes a motor assembly including a bearing assembly including a rotating component and at least one stationary component. The motor assembly also includes an impeller coupled to the rotating member. The impeller includes an inlet and an outlet and is configured to direct fluid between the inlet and the outlet. The motor assembly also includes a rotor assembly directly coupled to the impeller. A fluid flow passage is defined between the rotating component and the at least one stationary component. The flow passage includes a first end proximate the impeller outlet and a second end proximate the impeller inlet.

In yet another aspect, a method of assembling a pump assembly is provided. The method includes providing a bearing assembly including a rotating component and at least one stationary component. The method also includes coupling an impeller to the rotating component, wherein the impeller includes an inlet and an outlet and is configured to direct a fluid therebetween. The rotor assembly is directly coupled to the impeller. The method also includes defining a fluid flow path between the rotating component and the at least one stationary component. The flow passage includes a first end proximate the impeller outlet and a second end proximate the impeller inlet.

In one aspect, a fluid dynamic bearing assembly is provided. The fluid dynamic bearing assembly includes a first stationary component, a shaft coupled to the first stationary component, and a second stationary component coupled to the shaft opposite the first stationary component. The fluid dynamic bearing assembly also includes a rotating component coupled to the shaft between the first and second stationary components. The rotating component includes a first end face having a first diameter and an opposing second end face having a second diameter greater than the first diameter.

In another aspect, a pump assembly is provided. The pump assembly includes a fluid dynamic bearing assembly including a first stationary component, a shaft coupled to the first stationary component, and a second stationary component coupled to the shaft opposite the first stationary component. The fluid dynamic bearing assembly also includes a rotating component coupled to the shaft between the first and second stationary components. The rotating component includes a first end face having a first diameter and an opposing second end face having a second diameter greater than the first diameter. The pump assembly also includes an impeller coupled to the rotating component and a rotor assembly directly coupled to the impeller.

Drawings

FIG. 1 is a cross-sectional view of an exemplary centrifugal pump assembly including an impeller, a motor, and a fluid dynamic bearing;

FIG. 2 is an enlarged cross-sectional view of a portion of the centrifugal pump assembly bounded by box 2-2 in FIG. 1, illustrating exemplary flow channels through the centrifugal pump assembly;

FIG. 3 is an enlarged cross-sectional view of a portion of the centrifugal pump assembly shown in FIG. 1, illustrating an alternative flow passage through the centrifugal pump assembly;

FIG. 4 is a cross-sectional view of an alternative centrifugal pump assembly including an impeller, a motor, and a fluid dynamic bearing;

FIG. 5 is a cross-sectional view of a rotating component of the alternative fluid dynamic bearing shown in FIG. 4;

FIG. 6 is an axial end view of an end face of a rotating component illustrating a velocity profile of the rotating component of the fluid dynamic bearing assembly shown in FIG. 5;

FIG. 7 is an alternative rotary member that may be used with the alternative fluid dynamic bearing assembly shown in FIG. 4; and

FIG. 8 is another alternative rotating component that may be used with the alternative fluid dynamic bearing assembly shown in FIG. 4.

Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any figure may be referenced and/or claimed in combination with any feature of any other figure.

Detailed Description

Fig. 1 is a cross-sectional view of an exemplary centrifugal pump assembly 100 showing an axial flux motor assembly 102, an impeller 104, and a pump housing 106. Fig. 2 is an enlarged cross-sectional view of the motor assembly 102 and impeller 104, with the pump housing 106 removed for clarity. In the exemplary embodiment, pump assembly 100 includes a pump housing 106 and a motor housing 108. A pump housing 106 surrounds at least a portion of the motor assembly 102 and the impeller 104, while a motor housing 108 surrounds the motor assembly 102. The pump housing 106 includes a fluid inlet 110, a volute wall 112 defining a portion of a fluid flow cavity 114, and a fluid outlet 116. In operation, fluid flows through the inlet 110 and is directed through the channel 114 around the wall 112 until the fluid exits the pump 100 through the housing outlet 116.

In the exemplary embodiment, impeller 104 is positioned within pump housing 106 and includes an inlet ring 118 that defines an inlet opening 120. Impeller 104 also includes a back plate 122 and a plurality of blades 124 coupled between inlet ring 118 and back plate 122. As described in further detail herein, the back plate 122 of the impeller 102 is directly coupled to the motor assembly 102 such that the motor assembly 102 is configured to rotate the impeller 102 about an axis of rotation 126. In operation, the motor 102 rotates the impeller 104 about the axis 126 to draw fluid into the pump housing 106 in an axial direction through the housing inlet 110. The fluid is directed through the inlet openings 120 in the inlet ring 118 and is diverted by the vanes 124 within the channels 114 to direct the fluid radially through the housing outlet 116 along the wall 112. As the speed of impeller 104 increases, the amount of fluid moved by pump assembly 100 increases, causing impeller 104 to generate a high-speed fluid flow that is discharged from outlet 116.

As the impeller rotates, the impeller 104 imparts kinetic energy to the pumped fluid, which pressurizes the fluid. That is, a region 127 of negative pressure fluid exists upstream of impeller 104, and more specifically, upstream of impeller blades 124

proximate inlets

110 and 120. Accordingly, a region 129 of positive pressure fluid exists downstream of the impeller 104, proximate the outlet 116 of the housing 106. Thus, rotation of impeller 104 causes a pressure differential across impeller 104. In the exemplary embodiment, the negative pressure fluid exerts an axial suction force 128 on impeller 104. The axial force 128 acts in an axial direction away from the motor assembly 102 through the pump housing inlet 110. As the speed of the impeller 104 increases, the pressure of the fluid and the resulting axial suction force 128 also increase accordingly. That is, the magnitude of the axial suction force 128 is based on the rotational speed of the impeller 104.

In the exemplary embodiment, motor assembly 102 includes a stator assembly 130, which stator assembly 130 includes a magnetic stator core 134 and a plurality of conductor coils 136 positioned within motor housing 108. The motor assembly 102 also includes a bearing assembly 138 and a rotor assembly 140. Each conductor coil 136 includes an opening (not shown) that closely conforms to the exterior shape of one of the plurality of stator core teeth (not shown) such that each stator tooth is configured to be positioned within the conductor coil 136. The motor assembly 102 may include one conductor coil 136 per stator tooth or one conductor coil 136 positioned on every other tooth.

In the exemplary embodiment, a variable frequency drive (not shown) provides a signal, such as a Pulse Width Modulated (PWM) signal, to motor 102. In an alternative embodiment, the motor 102 may include a controller (not shown) coupled to the conductor coils 136 by wiring. The controller is configured to apply a voltage to one or more of the conductive coils 136 at a time to switch the conductive coils 136 in a preselected sequence to rotate the rotor assembly 140 about the axis 126.

The rotor assembly 140 is positioned within the pump housing 106 proximate the cavity 114 and includes a back iron or rotor disk 146 having at least a first axial surface 148. In the exemplary embodiment, rotor assembly 140 also includes a plurality of permanent magnets 152 that are directly coupled to rotor disk 146. In another embodiment, rotor assembly 140 includes a magnet holder (not shown) coupled to rotor disk 146 opposite wheel 104, and permanent magnets 152 are coupled to the magnet holder.

As best shown in fig. 1, impeller 104 is directly coupled to rotor assembly 140 opposite stator assembly 130 such that impeller 104 contacts rotor assembly 140 to enable rotation of impeller 104 and rotor assembly 140 about axis 126. As used herein, the term "directly" is intended to describe that the rotor assembly 140 is coupled to the impeller 104 without any intermediate structure positioned therebetween to separate the rotor assembly 140 from the impeller 104. More specifically, rotor disk 146 is directly coupled to wheel 104. More specifically, rotor disk 146 is directly coupled to back plate 122 of wheel 104. In one embodiment, axial surface 148 of rotor disk 146 is coupled to and directly contacts axial surface 164 of back plate 122 in a face-to-face relationship. In the exemplary embodiment, and as shown in FIG. 3, rotor disk 146 is coupled to impeller back plate 122 using a plurality of fasteners 166. In another embodiment, the rotor assembly 140 is integrally formed with the impeller 104. More specifically, the rotor disk 146 is integrally formed with the back plate 122 of the wheel 104 such that the rotor disk 146 and the back plate 122 form a single, unitary component. Generally, rotor assembly 140 and impeller 104 are directly coupled together using any attachment means that facilitates operation of pump assembly 100 as described herein.

In the exemplary embodiment, rotor assembly 140 is positioned adjacent stator assembly 130 to define an axial gap 154 therebetween. A liner (not shown) surrounds the stator assembly 130 to prevent the core 134 and coils 136 from being exposed to the fluid within the

housings

106 and 108. As described above, voltages are sequentially applied to the coils 136 to cause rotation of the rotor assembly 140. More specifically, the coils 136 control the flow of magnetic flux between the magnetic stator core 134 and the permanent magnets 152. Magnet 152 is attracted toward magnetic stator core 134 such that there is always an axial magnetic force (not shown) across gap 154. Accordingly, stator core 134 of stator assembly 130 applies an axial magnetic force to rotor assembly 140 in an axial direction away from impeller 104. More specifically, the axial magnetic force acts in a direction opposite the axial suction force 128 of the impeller 104. As the size of the axial gap 154 decreases, the axial magnetic force between the stator assembly 130 and the rotor assembly 140 increases. That is, the magnitude of the axial magnetic force is based on the length of the axial gap 154.

In the exemplary embodiment, impeller 104 includes a cylindrical extension 157 that extends axially from back plate 122 toward motor housing 108. More specifically, the extension 157 extends axially through the rotor assembly 140 and into the opening 132 defined by the stator core 134 to at least partially axially overlap the stator assembly 130. Further, the extension 157 is coupled to the rotational member 170 of the bearing assembly 138. The rotating component 170 circumscribes a stationary shaft 172 of the bearing assembly 138 and is axially positioned between a first stationary component 174 and a second stationary component 176 of the bearing assembly 138. In the exemplary embodiment, bearing assembly 138 includes a fluid dynamic bearing.

As best shown in fig. 2, fluid flow passages 178 are defined between the rotating and

stationary members

170, 172, 174, and 176. The passage 178 includes a first end 180 proximate the impeller outlet 116 and a second end 182 proximate the impeller inlet 120. In the exemplary embodiment, first end 180 is an inlet to passageway 178 and second end 182 is an outlet from passageway 178. Further, the first end 180 is located on a first axial side of the rotor assembly 140 and the second end 182 is located on an opposite second axial side of the rotor assembly 140. As described in further detail below, an inlet end 180 of the channel 178 corresponds to the outlet 116 of the impeller 104, and an outlet end 182 of the channel 178 corresponds to the inlet 120 of the impeller 104. Further, an inlet end 180 of the passage 178 corresponds to the positive pressure side 129 of the impeller 104, while an outlet end 182 of the passage 178 corresponds to the negative pressure side 127 of the impeller 104. In the exemplary embodiment, the pressure differential across impeller 104 between

regions

127 and 129 causes fluid to flow from passage inlet 180 through passage 178 to passage outlet 182 to provide working fluid to bearing assembly 138.

As shown in fig. 2, a portion of the passage 178 extends radially along the axial gap 154 between the rotor assembly 140 and the stator assembly 130, then follows the impeller extension 157 and encounters the bearing assembly 138. In the exemplary embodiment, passageway 178 includes a first radial portion 184 between rotating component 170 and first stationary component 174, an axial portion 186 between rotating component 170 and stationary shaft 172, and a second radial portion 188 between rotating component 170 and second stationary component 176 such that first radial portion 184, axial portion 186, and second radial portion 188 are in fluid communication in series. In addition, each of the first stationary member 174, the second stationary member 176, and the stationary shaft 172 includes a groove (not shown) formed therein to enable fluid to be present between the

stationary members

174, 172, and 176 and the rotating member 170 when the motor is started. First radial portion 184, axial portion 186, and second radial portion 188 of flow passage 178 extend along grooves in

stationary members

174, 172, and 176, respectively.

In operation, the conductor coils 136 coupled to the stator core 134 are energized in a time sequence that provides an axial magnetic field that moves clockwise or counterclockwise around the stator core 134 according to a predetermined sequence or sequence in which the conductor coils 136 are energized. The moving magnetic field intersects the flux field generated by the plurality of permanent magnets 152 to rotate the rotor assembly 140 in a desired direction about the axis 126 relative to the stator assembly 130. As described herein, since the rotor disk 146 is directly coupled to the impeller 104, rotation of the rotor disk 146 causes rotation of the impeller 104, which pressurizes fluid flowing from the inlet 120 through the impeller 104 to the outlet 116. The resulting pressure differential across the impeller 104 and rotor assembly 140 and positioning the channel inlet 180 on the positive pressure side 129 of the impeller 104 and the channel outlet 182 on the negative pressure side 127 of the impeller forces fluid through the flow channel 178. The fluid passing through the passage 178 pressurizes the bearing assembly 138 and overcomes the axial magnetic force between the stator assembly 130 and the rotor assembly 140 to enable the assembly 100 to operate as described herein. Thus, the pressure differential across impeller 104 and rotor assembly 140 enables bearing assembly 138 to be pressurized without the need for a separate pump.

Fig. 3 is an enlarged sectional view of a portion of the centrifugal pump assembly 100 shown in fig. 1, illustrating an alternative flow passage 190 through the centrifugal pump assembly 100. The flow passages 190 are substantially similar in operation and composition to the flow passages 178, except that the flow passages 190 extend radially inward along the axially outer surface of the stator assembly 130 rather than extending between the rotor assembly 140 and the stator assembly 130. Thus, the components shown in fig. 3 are identified by the same reference numerals as used in fig. 1 and 2.

As shown in fig. 3, a portion of the channel 190 extends axially between the outer surface of the stator assembly 130 and the motor housing 108 and then curves around the stator assembly 130 to extend radially between an axial end face of the stator assembly 130 and the motor housing 108. The flow passage 190 then extends through the opening 132 defined by the stator core 134 and then encounters the bearing assembly 138. Similar to the flow passage 178, the flow passage 190 includes a first radial portion 184 between the rotating component 170 and the first stationary component 174, an axial portion 186 between the rotating component 170 and the stationary shaft 172, and a second radial portion 188 between the rotating component 170 and the second stationary component 176 such that the first radial portion 184, the axial portion 186, and the second radial portion 188 are in series flow communication. In addition, each of the first stationary member 174, the second stationary member 176, and the stationary shaft 172 includes a groove (not shown) formed therein to enable fluid to be present between the

stationary members

174, 172, and 176, respectively.

In operation, the conductor coils 136 coupled to the stator core 134 are energized in a time sequence that provides an axial magnetic field that moves clockwise or counterclockwise around the stator core 134 according to a predetermined sequence or sequence in which the conductor coils 136 are energized. The moving magnetic field intersects the flux field generated by the plurality of permanent magnets 152 to rotate the rotor assembly 140 in a desired direction about the axis 126 relative to the stator assembly 130. As described herein, since the rotor disk 146 is directly coupled to the impeller 104, rotation of the rotor disk 146 causes rotation of the impeller 104, which pressurizes the fluid flowing from the inlet 120 through the impeller 104 to the outlet 116. The resulting pressure differential across the impeller 104 and rotor assembly 140 and positioning the channel inlet 180 on the positive pressure side 129 of the impeller 104 and the channel outlet 182 on the negative pressure side 127 of the impeller forces fluid through the flow channel 190. Fluid passing through passage 190 pressurizes bearing assembly 138 and overcomes the axial magnetic force between stator assembly 130 and rotor assembly 140 to enable assembly 100 to operate as described herein. Thus, the pressure differential across impeller 104 and rotor assembly 140 enables bearing assembly 138 to be pressurized without the need for a separate pump.

Fig. 4 shows an alternative embodiment of a centrifugal pump assembly 200. Centrifugal pump assembly 200 is substantially similar in operation and composition to centrifugal pump assembly 100 (shown in fig. 1) except that centrifugal pump assembly 200 includes an alternate rotating member 202 in bearing assembly 138 instead of rotating member 170 (shown in fig. 1). Further, centrifugal pump assembly 200 includes an alternative extension 204 of impeller 104 rather than extension 157 (as shown in fig. 1). Thus, the components shown in FIG. 3 are identified by the same reference numerals as used in FIG. 1.

FIG. 5 is a cross-sectional view of rotating component 202 of bearing assembly 138, and FIG. 6 is an axial end view of an end face of rotating component 202 illustrating a velocity profile of rotating component 202.

In this embodiment, to ensure bearing lift, the bearing assembly 138 is designed such that the Pressure Velocity (PV) factor falls within a predetermined range. The PV factor is based on the speed of the rotating component 202 and the coefficient of friction between the rotating component 202 and the second stationary component 176. However, as shown in FIG. 6, the circular shape of the rotating component 202 results in a speed differential between the inner and outer diameters of the disk rotating component 202. In at least some known bearing assemblies, this speed differential may result in a wide range of PV factors along the radius, at least some of which may be outside of a desired range. However, as described herein, rotational component 202 of bearing assembly 138 includes a shape such that each point along a radius of rotational component 202 has the same PV factor as each other point along the radius.

As shown in fig. 5, rotating component 202 includes a first end face 206, an opposing second end face 208, and a body surface 210 extending therebetween. Body surface 210 comprises a radially outer surface of rotating component 202 along at least a portion of the axial length of rotating component 202. The first end face 206 includes a first diameter D1 and the second end face 208 includes a second diameter D2, the second diameter D2 being greater than the first diameter D1. Further, rotating component 202 includes the same inner diameter ID at both end faces 206 and 208. However, rotating component 202 includes a first outer diameter OD1 at first end face 206 and a second outer diameter OD2 at second end face 208. Such that second outer diameter OD2 is radially offset from first outer diameter OD 1. As such, the first end face 206 includes a first width W1 between the inner diameter ID and the first outer diameter OD 1. Similarly, the second end face 208 includes a second width W2 between the inner diameter ID and the second outer diameter OD2, wherein the second width W2 is greater than the first width W1. In addition, the inner diameter ID and the first outer diameter OD1 both have a first axial length L1, while the second outer diameter OD2 includes a second axial length L2 that is less than the first axial length L1.

As shown in fig. 4, the second end face 208 is positioned adjacent the second stationary component 176 and the first end face 206 is positioned adjacent the first stationary component 174. Alternatively, the first end face 206 is positioned adjacent the second stationary member 176 and the second end face 208 is positioned adjacent the first stationary member 174. Further, in this embodiment, the rotating component 202 is a single unitary piece. In another embodiment, rotating component 202 is a plurality of components coupled together.

It can be seen that the shape of body surface 210 is such that the diameter of rotating component 202 changes based on position along the axial length of rotating component 202. The changing diameter causes a distributed force along the first end face 206 and the body surface 210 as indicated by arrows 212. The arrows indicate that as the diameter of rotating component 202 increases along axis 126, less axial force is applied to rotating component 202 such that a rotating component near first end face 206 is applied with a greater force than a rotating component near second end face 208. As shown in fig. 4, the body surface 210 includes a non-linear surface extending between the first and second end faces 206, 208. More specifically, the body surface 210 comprises a continuously curved surface.

Fig. 7 is an alternative rotating member 300 that may be used with the fluid dynamic bearing assembly 138 shown in fig. 4. As shown in fig. 7, rotating component 300 includes a body surface 310 that extends linearly between first end face 206 and second end face 208. In such embodiments, linear body surface 310 is oriented obliquely with respect to rotational axis 126. As shown in fig. 7, linear body surface 310 also has a constant slope between first end face 206 and second end face 208.

Fig. 8 is another alternative rotating member 400 that may be used with the fluid dynamic bearing assembly 138 shown in fig. 4. As shown in fig. 8, rotary component 400 includes a stepped body surface 410 extending between first end face 206 and second end face 208. Generally, body surface 210 of rotating component 202 is any one of non-linear, stepped, or any combination thereof, which facilitates operation of rotating component 202 as described herein.

Referring back to FIG. 6, second end face 208 defines a radius R between inner diameter ID and second outer diameter OD 2. The ramp rate of rotating component 202 is shown by arrow 214 on second end face 208. The fade rate 214 for the rotating component 202 shows that points closer to the inner diameter ID along the radius R, represented by the length of arrow 214, move more slowly than points closer to the second outer diameter OD2 along the radius R. The gradual distribution force 212 generated on the rotating component 202 by changing the diameter with length compensates for the gradual velocity 214 along the radius R. This configuration results in an optimal, narrower PV factor range at the radius R of the second end face 208. More specifically, the PV factor of rotating component 202 is substantially similar at each point along radius R. Still more specifically, the second end face 208 includes a first point 216 that is a first distance D1 from the midpoint or axis 124 of the surface 208. Rotating component 202 includes a first PV factor at a first point 216. Similarly, the second end face 208 includes a second point 218 that is a second distance D2 from the midpoint or axis 124 of the face 208. Rotating component 202 includes a second PV factor at a second point 218. As described herein, the first and second PV factors at the first point 216 and the second point 218 along the radius R are substantially similar to each other, although the speed of the rotating component 202 is graduated due to the change in diameter over the axial length of the rotating component 202. The substantially constant PV factor at the end face 208 causes the bearing assembly 138 to operate more efficiently and the useful life of the rotating component 202 and the

stationary components

174 and 176 to increase.

Referring back to fig. 4, impeller 104 includes an extension 204 that extends axially from back plate 122 toward motor housing 108 and is coupled to rotational member 202 of bearing assembly 138. Extension 204 includes a radially inner surface 220 that corresponds in shape to the shape of body surface 210 of rotating component 202. That is, in embodiments where the body surface 210 is curved, as shown in FIG. 4, the inner surface 220 is correspondingly curved. Generally, the radially inner surface 220 is any shape that matches or corresponds to the shape of the body surface 210 to facilitate operation of the assembly 200 as described herein.

In operation, the conductor coils 136 coupled to the stator core 134 are energized in a time sequence that provides an axial magnetic field that moves clockwise or counterclockwise around the stator core 134 according to a predetermined sequence or sequence of energization of the conductor coils 136. The moving magnetic field intersects the flux field generated by the plurality of permanent magnets 152 to rotate the rotor assembly 140 in a desired direction about the axis 126 relative to the stator assembly 130. As described herein, since the rotor disk 146 is directly coupled to the impeller 104, rotation of the rotor disk 146 causes rotation of the impeller 104, which pressurizes fluid flowing from the inlet 120 through the impeller 104 to the outlet 116. The resulting pressure differential across the impeller 104 and rotor assembly 140 and positioning the channel inlet 180 on the positive pressure side 129 of the impeller 104 and the channel outlet 182 on the negative pressure side 127 of the impeller forces fluid through the flow channel 178. Fluid passing through passage 178 pressurizes bearing assembly 138 and overcomes the axial magnetic force between stator assembly 130 and rotor assembly 140 to enable assembly 100 to operate as described herein.

The apparatus, methods, and systems described herein provide a pump assembly having an electric motor coupled to an impeller. More specifically, the rotor assembly of the motor is directly coupled to the impeller. The impeller includes an inlet and an outlet and is configured to direct fluid therebetween and is also coupled to a rotating component of the bearing assembly. A fluid flow passage is defined between the rotating component and at least one stationary component of the bearing assembly. The flow passage includes an inlet adjacent the impeller outlet and an outlet adjacent the impeller inlet. As described herein, since the rotor disk is directly coupled to the impeller, rotation of the rotor disk causes rotation of the impeller, which pressurizes fluid flowing from the impeller inlet to the impeller outlet. The resulting pressure differential across the impeller, in combination with positioning the channel inlet on the positive pressure side of the impeller and the channel outlet on the negative pressure side, forces fluid through the flow channel. Fluid passing through the flow passage pressurizes the bearing assembly to enable the assembly 100 to operate as described herein without the need for a separate pump.

Further, tapering the diameter of the rotating component of the bearing assembly over its length to have a gradual distribution of force compensates for the gradual rate of change along the radius of the end face of the rotating component. Such a configuration results in an optimally narrower PV factor range at the end face radius. The substantially constant PV factor across the rotating component faces causes the bearing assembly to operate more efficiently and its rotating and stationary components to have an increased useful life.

Exemplary embodiments of centrifugal pump assemblies are described above in detail. The centrifugal pump assembly and its components are not limited to the specific embodiments described herein, but rather, components of the system may be utilized independently and separately from other components described herein. For example, the various components may also be used in combination with other machine systems, methods, and apparatus, and are not limited to practice with only the systems and apparatus as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other applications.

Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they do not differ from the structural elements described in the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. An electric motor assembly comprising:

a bearing assembly comprising a rotating component and at least one stationary component;

an impeller coupled to the rotating component, wherein the impeller includes an inlet and an outlet and is configured to direct a fluid therebetween; and

a rotor assembly directly coupled to the impeller such that the rotating component is radially coupled between the at least one stationary component and the impeller, wherein a fluid flow passage is defined between the rotating component and the at least one stationary component, the fluid flow passage including a first end proximate an outlet of the impeller and a second end proximate an inlet of the impeller;

a stator assembly positioned adjacent the rotor assembly to define an axial gap therebetween, wherein the impeller includes an extension positioned radially between the stator assembly and the rotating component, the fluid flow channels directing fluid axially along a radial end of the stator assembly, radially along an axial end of the stator opposite the rotor, radially between the rotating component and the at least one stationary component, and axially between the rotating component and the at least one stationary component toward the second end.

2. The motor assembly of claim 1, wherein the impeller is configured to pressurize the fluid such that the fluid is at a negative pressure at an inlet of the impeller and at a positive pressure at an outlet of the impeller.

3. The motor assembly of claim 2, wherein the first end comprises an inlet of the fluid flow channel, and wherein the second end comprises an outlet of the fluid flow channel.

4. The motor assembly of claim 1, wherein a portion of the fluid flow passage extends along the axial gap.

5. The electric motor assembly of claim 1, wherein the at least one stationary component comprises a first stationary component, a second stationary component, and a stationary shaft coupled therebetween.

6. The motor assembly of claim 5, wherein the fluid flow passage comprises:

a first radial portion between the rotating component and the first stationary component;

a second radial portion between the rotating component and the second stationary component; and

an axial portion between the rotating component and the stationary shaft.

7. The motor assembly of claim 6, wherein the first radial portion, the axial portion, and the second radial portion are in series flow communication.

8. The motor assembly of claim 1, wherein the first end is located on a first axial side of the rotor assembly and the second end is located on an opposite second axial side of the rotor assembly.

9. A pump assembly, comprising:

a pump housing;

a motor housing coupled to the pump housing; and

a motor assembly, comprising:

a bearing assembly comprising a rotating component and at least one stationary component, wherein the at least one stationary component comprises:

a shaft including a first axial end face and a second axial end face;

a first stationary member coupled to the first axial end face;

a second stationary member coupled to the second axial end face; and

an impeller coupled to the rotating component, wherein the impeller includes an extension, an inlet, and an outlet and is configured to direct a fluid therebetween;

a rotor assembly directly coupled to the impeller such that the rotating component is radially coupled between the shaft and the impeller, wherein a fluid flow passage is defined between the rotating component and the at least one stationary component, the fluid flow passage including a first end proximate an outlet of the impeller and a second end proximate an inlet of the impeller, the fluid flow passage directing fluid axially between the stator assembly and the motor housing, directing fluid radially between the rotating component and the at least one stationary component, directing fluid axially between the rotating component and the at least one stationary component toward the second end.

10. The pump assembly of claim 9, wherein the impeller is configured to pressurize the fluid such that the fluid is at a negative pressure at an inlet of the impeller, and wherein the fluid is at a positive pressure at an outlet of the impeller, wherein the first end comprises an inlet of the fluid flow passage, and wherein the second end comprises an outlet of the fluid flow passage.

11. The pump assembly of claim 9, further comprising a stator assembly positioned adjacent the rotor assembly, wherein a portion of the fluid flow passage extends between the motor housing and the stator assembly.

12. The pump assembly of claim 9, wherein the fluid flow channel comprises:

an axial portion between the rotating component and a stationary shaft, wherein the first radial portion, the axial portion, and the second radial portion are in series flow communication.

13. The pump assembly of claim 9, wherein the first end is located on a first axial side of the rotor assembly and the second end is located on an opposite second axial side of the rotor assembly.

14. A method of assembling a pump assembly, the method comprising:

providing a bearing assembly comprising a rotating component and at least one stationary component;

coupling an impeller to the rotating component, wherein the impeller includes an inlet and an outlet and is configured to direct a fluid therebetween;

coupling a rotor assembly directly to the impeller such that the rotating component is radially coupled between the at least one stationary component and the impeller;

coupling a stator assembly adjacent the rotor assembly such that an extension of the impeller is positioned radially between the stator assembly and the rotating component; and

a fluid flow passage is defined between the rotating component and the at least one stationary component, the fluid flow passage including a first end proximate the outlet of the impeller and a second end proximate the inlet of the impeller, wherein the fluid flow passage directs fluid axially along a radial end of the stator assembly, radially along an axial end of the stator opposite the rotor, radially between the rotating component and the at least one stationary component, and axially between the rotating component and the at least one stationary component toward the second end.

15. The method of claim 14, wherein coupling the impeller to the rotating component comprises coupling the impeller to the rotating component such that the impeller is configured to pressurize the fluid, wherein the fluid is at a negative pressure at an inlet of the impeller, and wherein the fluid is at a positive pressure at an outlet of the impeller.

16. The method of claim 14, wherein defining the fluid flow channel comprises defining the fluid flow channel to include an inlet at the first end and an outlet at the second end.

17. The method of claim 14, further comprising coupling a stator assembly adjacent the rotor assembly to define an axial gap therebetween, wherein a portion of the fluid flow passage extends along the axial gap.

18. The method of claim 14, wherein defining the fluid flow passage includes defining the first end at a first axial side of the rotor assembly and defining the second end at an opposing second axial side of the rotor assembly.

19. The method of claim 14, wherein the first and second light sources are selected from the group consisting of,

wherein providing a bearing assembly comprising at least one stationary component comprises: providing a bearing assembly comprising a first stationary component, a second stationary component, and a stationary shaft coupled therebetween; and is

Wherein defining a fluid flow passage between the rotating component and the at least one stationary component comprises:

a first radial portion of the fluid flow passage defined between the rotating component and the first stationary component;

a second radial portion of the fluid flow passage defined between the rotating component and the second stationary component; and

an axial portion of the fluid flow passage defined between the rotating component and the stationary shaft.