CN110462218B

CN110462218B - Centrifugal pump assembly with axial flux motor and method of assembling the same

Info

Publication number: CN110462218B
Application number: CN201880021409.8A
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; Rebecca America
Current assignee: Regal Beloit Australia Pty Ltd; Rebecca America
Priority date: 2017-01-27
Filing date: 2018-01-26
Publication date: 2021-09-10
Anticipated expiration: 2038-01-26
Also published as: EP3574217A1; CN110462218A; EP3574217A4; AU2018213369A1; WO2018140724A1

Abstract

A motor assembly for pumping a fluid through a fluid chamber includes a stator assembly including a plurality of electrically conductive coils configured to transfer thermal energy to the fluid within the fluid chamber, and a rotor assembly positioned adjacent the stator assembly to define an axial gap therebetween. The stator assembly is configured to exert a first axial force on the rotor assembly. The motor assembly also includes an impeller directly coupled to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The fluid directed by the impeller exerts a second axial force on the impeller. The rotor assembly and impeller are configured to be submerged in a fluid within the fluid cavity.

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.15/418,146 filed on day 27, month 1, 2017 and U.S. patent application No.15/418,103 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 to a shaft that is also coupled to a rotor of the motor such that rotation of the rotor causes rotation of the impeller. In at least some known electric motors, the rotor is spaced from the stator such that there is always an axial attractive force between the magnets on the rotor and the steel core of the stator. The axial force may be large enough that the bearing system of the motor requires special design considerations to withstand the axial force. In addition, the rotating impeller distributes kinetic energy into the pumped fluid as it rotates, which increases the pressure of the fluid. As a result of this pressure increase, an axial suction force acting on the impeller is generated. In at least some known centrifugal pumps, axial suction may also require bearing system design considerations.

Furthermore, at least some known centrifugal pumps are located in environments that may cause the fluid directed therethrough to freeze while the pump is not operating. When the fluid freezes, the impeller may be locked in place, and subsequent attempts to rotate the impeller before defrosting the fluid may result in a shortened useful life of the impeller or the entire pump. In addition, in at least some centrifugal pumps, the stator of the electric motor generates relatively high heat and may require complex and costly cooling systems.

Disclosure of Invention

In one aspect, a motor assembly is provided. The motor assembly includes a stator assembly and a rotor assembly positioned adjacent the stator assembly to define an axial gap therebetween. The stator assembly is configured to exert a first axial force on the rotor assembly. The motor assembly also includes an impeller directly coupled to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The fluid directed by the impeller exerts a second axial force on the impeller.

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 stator assembly and a rotor assembly positioned adjacent the stator assembly to define an axial gap therebetween. The stator assembly is configured to exert a first axial force on the rotor assembly. The motor assembly also includes an impeller directly coupled to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The fluid directed by the impeller exerts a second axial force on the impeller.

In yet another aspect, a method of assembling a pump assembly is provided. The method includes providing a stator assembly and coupling the rotor assembly to the stator assembly such that an axial gap is defined therebetween. The stator assembly is configured to exert a first axial force on the rotor assembly. The method also includes directly coupling the impeller to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The fluid directed by the impeller is configured to exert a second axial force on the impeller.

In one aspect, a motor assembly for pumping a fluid through a fluid chamber is provided. The motor assembly includes a stator assembly including a plurality of electrically conductive coils configured to transfer thermal energy to a fluid within a fluid cavity. The motor assembly also includes a rotor assembly positioned adjacent the stator assembly to define an axial gap therebetween. The motor assembly also includes an impeller directly coupled to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The rotor assembly and impeller are configured to be submerged in a fluid within the fluid cavity.

In yet another aspect, a pump assembly is provided. The pump assembly includes a pump housing defining a fluid chamber and a motor housing coupled to the pump housing. The pump assembly also includes a motor assembly including a stator assembly positioned within the motor housing and including a plurality of electrically conductive coils configured to transfer thermal energy to the fluid within the fluid cavity. The motor assembly also includes a rotor assembly positioned adjacent the stator assembly and within the pump housing. The motor assembly also includes an impeller directly coupled to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The rotor assembly and impeller are configured to be submerged in a fluid within the fluid cavity.

In yet another aspect, a method of assembling a pump assembly for pumping a fluid through a fluid chamber is provided. The method includes providing a stator assembly having a plurality of electrically conductive coils configured to transfer thermal energy to a fluid within a fluid cavity. The method also includes positioning the rotor assembly adjacent the stator assembly such that an axial gap is defined therebetween, and directly coupling the impeller to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis. The rotor assembly and impeller are configured to be submerged in a fluid within the fluid cavity.

Drawings

FIG. 1 is a perspective view of an exemplary centrifugal pump;

FIG. 2 is a sectional view of the centrifugal pump shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the centrifugal pump shown in FIG. 2, showing the motor and impeller;

FIG. 4 is a perspective view of an alternate embodiment of a centrifugal pump;

FIG. 5 is a bottom perspective view of the centrifugal pump shown in FIG. 4, showing the impeller;

FIG. 6 is a sectional view of the centrifugal pump shown in FIG. 4, showing the impeller and the motor; and

fig. 7 is an enlarged cross-sectional view of the portion of the motor and impeller surrounded by frame 7-7 in fig. 6.

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 perspective view of an exemplary centrifugal pump assembly 100. Fig. 2 is a cross-sectional view of pump assembly 100, showing axial flux motor assembly 102, impeller 104, and pump housing 106. Fig. 3 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 vortex wall 112 defining a portion of a fluid flow passage 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 the impeller 104 increases, the amount of fluid moved by the pump assembly 100 increases such that the impeller 104 generates a high-speed fluid flow that is discharged from the outlet 116.

As the impeller rotates, the impeller 104 imparts kinetic energy to the pumped fluid, which pressurizes the fluid. In the exemplary embodiment, the pressurized 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 motor housing 108, and motor housing 108 includes a first portion 130 and a second portion 132. Motor assembly 102 also includes a stator assembly 133, which stator assembly 133 includes a magnetic stator core 134 and a plurality of conductor coils 136. 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 outer shape of one of the plurality of stator core teeth 142 such that each stator tooth 142 is configured to be positioned within the conductor coil 136. The motor assembly 102 may include one conductor coil 136 per stator tooth 142 or one conductor coil 136 per every other tooth 142. The stator core 134 and coils 136 are positioned within a second portion 132 of the motor housing 108, the second portion 132 being coupled to the pump housing 106 with a plurality of fasteners 144.

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 voltage to one or more of the conductor coils 136 at a time to switch (communicate) the conductor 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 to the channel 114 and includes a back iron or rotor disk 146 having at least a first axial surface 148. Rotor assembly 140 also includes a magnet holder 150 coupled to rotor disk 146 opposite wheel 104 and a plurality of permanent magnets 152 coupled to magnet holder 150 using an adhesive. Alternatively, the magnet 152 may be coupled to the magnet holder 150 using any retention method that facilitates operation of the motor 102 as described herein. In another embodiment, magnets 152 are directly coupled to rotor disk 146.

In the exemplary embodiment, rotor assembly 140 is positioned adjacent stator assembly 133 to define an axial gap 154 therebetween. As described above, a voltage is 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. The magnet 152 is attracted toward the magnetic stator core 134 such that there is always an axial magnetic force 156 through the gap 154. As such, stator core 134 of stator assembly 133 distributes axial magnetic force 156 to rotor assembly 140 in an axial direction away from impeller 104. More specifically, the axial magnetic force 156 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 156 between the stator assembly 133 and the rotor assembly 140 increases. That is, the magnitude of the axial magnetic force 156 is based on the length of the axial gap 154.

Rotor disk 146 is coupled to a rotating component 158 of bearing assembly 138, and stator assembly 133 is coupled to a stationary component 160 of bearing assembly 138. In the exemplary embodiment, bearing assembly 138 includes a hydrodynamic bearing in which a rotating member 158 is coupled to rotor disk 146 using a plurality of fasteners 162. In other embodiments, the bearing assembly 138 includes any bearing type that facilitates operation of the motor 102 as described herein.

As best shown in fig. 3, 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. As described above, conventional pumps include a shaft coupling a rotor assembly to an impeller. However, in one embodiment described herein, as shown in fig. 2 and 3, pump assembly 100 does not include a shaft coupled between rotor assembly 140 and impeller 104 because impeller 104 is directly coupled to rotor assembly 140 and in contact with rotor assembly 140.

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 133. As described above, the magnetic attraction between stator core 134 and magnets 152 generates an axial magnetic force 156 that acts in a direction away from impeller 104. Further, since the rotor disk 146 is directly coupled to the wheel 104, rotation of the rotor disk 146 causes rotation of the wheel 104. As described above, rotation of the impeller 104 pressurizes the fluid flowing therethrough, which applies an axial suction force 128 to the impeller 104 in a direction away from the rotor assembly 140. As shown in FIG. 3, the axial attractive force 128 acts in the opposite direction of the axial magnetic force 156. In this embodiment, when rotor disk 146 is directly coupled to impeller 104, axial magnetic force 156 resists axial suction force 128 to reduce the sum of forces, which facilitates extending the service life of bearing assembly 138. In some embodiments,

forces

156 and 128 are equal such that they cancel each other.

Further, in the exemplary embodiment, axial gap 154 is adjustable to vary a magnitude of axial magnetic force 156. Additionally, the motor assembly 102 is a variable speed motor, and thus the speed of the impeller 104 may also be adjusted to adjust the axial suction 128 of the fluid. Modifying at least one of the speed of impeller 104 and air gap 154 facilitates creating a desired bias within pump assembly 100 toward motor assembly 102 or toward pump 106. Thus, by reducing the resultant force within the pump assembly 100 and biasing the resultant force toward the motor assembly 102 or the pump 106, a simple and low cost bearing assembly 138 may be used with the integrated pump assembly 100.

FIG. 4 is a perspective view of an alternative embodiment of the centrifugal pump assembly 200 showing the pump housing 206 and the motor housing 208. FIG. 5 is a bottom perspective view of centrifugal pump assembly 200 with pump housing 206 removed and impeller 204 shown for clarity. Fig. 6 is a cross-sectional view of pump assembly 200 showing impeller 204 and axial flux motor assembly 202, and fig. 7 is an enlarged cross-sectional view of motor assembly 202 and the portion of impeller 204 defined by box 7-7 in fig. 6.

In the exemplary embodiment, pump assembly 200 includes a pump housing 206 and a motor housing 208. A pump housing 206 surrounds at least a portion of the motor assembly 202 and the impeller 204, while a motor housing 208 surrounds the motor assembly 202. The pump housing 206 includes a fluid inlet 210, a volute wall 212 defining a portion of a fluid flow passage 214, and a fluid outlet 216. In operation, fluid flows through the inlet 210 and is directed through the channel 214 around the wall 212 until the fluid exits the pump 200 via the housing outlet 216.

In the exemplary embodiment, impeller 204 is positioned within pump housing 206 and includes an inlet ring 218 that defines an inlet opening 220. Impeller 204 also includes a back plate 222 and a plurality of blades 224 coupled between inlet ring 218 and back plate 222. As described in further detail herein, the back plate 222 of the impeller 202 is directly coupled to the motor 202 such that the motor 202 is configured to rotate the impeller 202 about the axis of rotation 226. In operation, the motor 202 rotates the impeller 204 about the axis 226 to draw fluid in an axial direction through the housing inlet 210 into a fluid chamber 228 defined by the pump housing 206. Fluid is directed through inlet openings 220 in inlet ring 218 and is diverted by vanes 224 within passage 214 to direct fluid along wall 212 within cavity 228 through housing outlet 216. As the speed of impeller 204 increases, the amount of fluid moved by pump assembly 200 increases such that impeller 204 generates a high velocity fluid flow that is discharged from outlet 216.

In the exemplary embodiment, motor assembly 202 includes a stator assembly 232, stator assembly 232 including a magnetic stator core 234 and a plurality of conductor coils 236. The motor assembly 202 also includes a bearing assembly 238 and a rotor assembly 240. Each conductor coil 236 includes an opening (not shown) that closely conforms to the outer shape of one of the plurality of stator core teeth 242 such that each stator tooth 242 is configured to be positioned within the conductor coil 236. The motor assembly 202 may include one conductor coil 236 per stator tooth 242 or one conductor coil 236 positioned on every other tooth 242.

In the exemplary embodiment, motor assembly 202 also includes an electronics module 244 that controls operation of motor assembly 202. In one embodiment, the electronics module 244 is coupled to the conductor coils 236 by wiring and is configured to apply a voltage to one or more of the conductor coils 236 at a time for switching the conductor coils 236 in a preselected sequence to rotate the rotor assembly 240 about the axis 226. As shown in fig. 6, the electronics module 244 is coupled to the stator assembly 232 and is positioned with the stator assembly 232 within a cavity 245 defined by the motor housing 208.

The rotor assembly 240 is positioned within the fluid cavity 228 of the pump housing 206 and includes a back iron or rotor disk 246 having at least a first axial surface 248 (shown in fig. 7). In the exemplary embodiment, rotor assembly 240 also includes at least one permanent magnet 250 that is coupled to rotor disk 246 opposite impeller 204 using an adhesive. Alternatively, magnets 250 may be coupled to rotor disk 246 using any retention method that facilitates operation of electric motor assembly 202 as described herein. In another embodiment, the magnet 250 is coupled to a magnet holder, which in turn is coupled to the rotor disk 246. Further, the magnet 250 is a single ring magnet or one of a plurality of magnets.

In the exemplary embodiment, rotor assembly 240 is positioned adjacent stator assembly 232 to define an axial gap 254 (shown in FIG. 7) therebetween. Moreover, impeller 204 is directly coupled to rotor assembly 240 opposite stator assembly 232 such that impeller 204 and rotor assembly 240 rotate about axis 226 and are positioned within fluid cavity 228 and are submerged in the fluid within fluid cavity 228. More specifically, rotor disk 246 is coupled to impeller 204. Still more specifically, rotor disk 246 is coupled to back plate 222 of wheel 204. In one embodiment, axial surface 248 of rotor disk 246 is coupled in a face-to-face relationship to axial surface 255 of backplate 222. In the exemplary embodiment, and as shown in FIG. 7, rotor disk 246 is coupled to wheel back plate 222 using a plurality of fasteners 257. In another embodiment, rotor assembly 240 is integrally formed with impeller 204. More specifically, rotor disk 246 is integrally formed with back plate 222 of wheel 204. Generally, rotor assembly 240 and impeller 204 are coupled directly together using any attachment means that facilitates operation of pump assembly 200 as described herein.

In the exemplary embodiment, impeller 204 includes a cylindrical extension 256 that extends axially from back plate 222 toward motor housing 208. Extension 256 is coupled to rotational member 258 of bearing assembly 238. The rotating member 258 circumscribes a stationary member 260 of the bearing assembly 238. In the exemplary embodiment, bearing assembly 238 includes a fluid dynamic bearing. In other embodiments, the bearing assembly 238 includes any bearing type that facilitates operation of the motor 102 as described herein.

As best shown in fig. 7, the motor housing 208 also includes a wall 262 that separates the fluid chamber 228 from the stator assembly 232 and at least partially defines the cavity 245. More specifically, the wall 262 restricts the flow of fluid within the pump housing 206 and substantially seals the stator assembly 232 and the electronics module 244 from the fluid chamber 228. In the exemplary embodiment, wall 262 includes an axial portion 264, and axial portion 264 is located directly radially inward of conductor coil 236, such that a radial gap 266 is formed between wall axial portion 264 and wheel extension 256. As described herein, the gap 266 enables fluid flow between the wall 262 of the motor housing 208 and the extension 256 of the impeller 204. In addition, the wall 262 also includes a radial portion 268, the radial portion 268 extending radially within the axial gap 254 between the stator assembly 232 and the rotor assembly 240. In addition, wall 262 defines a fluid passage 270 that is in fluid communication with fluid chamber 228 radially outward of conductor coil 236. In the exemplary embodiment, walls 264 and 268 form a barrier between fluid chamber 228 and a motor chamber 245 that houses stator assembly 232 and electronics module 244, as described in further detail below. The walls 264 and 268 are positioned adjacent the conductor coil 236 such that when heating is desired, heat from the conductor coil 236 is transferred through the walls 264 and 268 to heat the fluid within the fluid chamber 228. Similarly, during operation, the relatively cool fluid flowing through the wall 262 is used to cool the conductor coils 236 and the stator core 234 of the stator assembly 232, and also to cool the electronics module 244.

In operation, the electronics module 244 is configured to apply a voltage to one or more of the conductive coils 236 at a time for switching the conductive coils 236 in a preselected sequence to rotate the rotor assembly 240 about the axis 226. The conductor coils 236 coupled to the stator core 234 are energized in a time sequence that provides an axial magnetic field that moves clockwise or counterclockwise around the stator core 234 according to a predetermined sequence or sequence in which the conductor coils 236 are energized. The moving magnetic field intersects the flux field generated by the permanent magnets 250 to rotate the rotor assembly 240 about the axis 226 in a desired direction relative to the stator assembly 232.

In the exemplary embodiment, the voltage applied to conductor coil 236 may be controlled such that electrical energy within conductor coil 236 is converted to thermal energy 272 that is radiated from coil 236. In addition, a frequency is applied to the conductor coils 236 to alter the magnetic flux in the rotor assembly 240 such that the electromagnetic components of the rotor assembly 240, i.e., the rotor disk 246, are heated. Thermal energy 272 radiates from the conductor coil 236 and is transferred to the fluid within the fluid chamber 228. More specifically, thermal energy 272 is transferred from the conductor coil 236 through the axial portion 264 and the radial portion 268 of the wall 262 to the fluid within the fluid cavity 228. Moreover, because rotor assembly 240 is positioned proximate to stator assembly 232, thermal energy 272 also helps to heat magnet 250 and/or rotor disk 246, causing the temperature of the fluid in the immediate vicinity of magnet 250 and/or rotor disk 246 to increase. Induction heating of the pump assembly 200 as described herein is used to prevent freezing of fluid or to defrost frozen fluid.

In the exemplary embodiment, pump assembly 200 can be located in an environment such that the fluid within fluid chamber 228 freezes when pump assembly 200 is not operating. Since rotor assembly 240 and impeller 204 are submerged in the fluid, rotor assembly 240 and impeller 204 may be locked into place when the fluid freezes. In this case, the voltage may be applied in such a manner as to heat the conductor coil 236 without causing the rotor assembly 240 to rotate. Thermal energy 272 is then transferred to the cryogenic fluid and magnets 250 and/or rotor disk 246 via wall 262 to facilitate thawing the fluid, thereby enabling rotation of submerged rotor assembly 240 and impeller 204. Specifically, thermal energy 272 is transferred to axial gap 254 and radial gap 266 to facilitate heating the fluid therein. Coupling rotor assembly 240 to impeller 204 and positioning rotor assembly 240 and impeller 204 within fluid cavity 228 and also in close proximity to conductor coils 236 of stator assembly 232 enables thermal energy 272 to warm the fluid within cavity 272 and also warm magnet 250 and/or rotor disk 246. Further, submerging rotor assembly 240 in the fluid within fluid cavity 228 exposes rotor assembly 240 to the fluid, which facilitates cooling magnets 250 and/or rotor disk 246 and prevents rotor assembly 240 from exceeding a predetermined temperature limit.

Additionally, during standard operation, both the conductor coil 236 and the electronics module 244 generate heat, which may require cooling to prevent the conductor coil 236 and the electronics module 244 from exceeding predetermined temperature limits. In the exemplary embodiment, conductor coil 236 and electronics module 244 are positioned with motor housing 208 of pump assembly 200 proximate fluid cavity 228. As described above, the relatively cool fluid flows along the axial and radial portions 264, 268 of the wall 262, causing the temperature of the wall 262 to decrease. The cooled wall 262 reduces the temperature of the motor cavity 245, which facilitates cooling the conductor coil 236 and the electronics module 244 within the cavity 245. The electronic module 244 and the conductor coil 236 within the motor cavity 245 proximate to the fluid within the fluid cavity 228 of the pump housing 206 help to reduce the temperature of the conductor coil 236 and the electronic module 244.

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 rotor assembly receives axial suction from the stator assembly and the impeller receives axial suction from the fluid flowing therethrough. As described herein, the axial attractive force acts in a direction opposite the axial magnetic force to reduce the sum of the forces, which facilitates extending the useful life of the motor assembly, particularly the bearing assembly.

Further, directly coupling the rotor assembly and the impeller and positioning the rotor assembly adjacent the stator assembly enables heat to be transferred from the stator assembly to the rotor assembly and the fluid within the pump. More specifically, a voltage is applied to the plurality of conductor coils of the stator assembly to heat the conductor coils. Thermal energy is radiated from the conductor coils and transferred through the wall of the motor housing to the rotor assembly and to the fluid in which the rotor assembly is submerged, so as to warm the fluid and the rotor assembly. Additionally, immersing the rotor assembly in the fluid exposes the rotor assembly to the fluid, which facilitates cooling components of the rotor assembly and prevents overheating of the rotor assembly. Additionally, the fluid within the fluid cavity of the pump housing proximate to the electronics module and conductor coil within the motor cavity facilitates cooling of the conductor coil and electronics module.

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 stator assembly;

a rotor assembly positioned adjacent to the stator assembly to define an axial gap therebetween, wherein the stator assembly exerts a first axial force on the rotor assembly;

a bearing assembly, the bearing assembly comprising:

a rotating member having a stepped radial portion directly coupled to a rotor disk of the rotor assembly opposite the stator assembly, wherein the stepped radial portion is aligned with two inner surfaces of the rotor disk of the rotor assembly along an axis of rotation; and

a stationary member located radially outward of the rotating member, wherein the rotating member includes an axial portion located within an opening of the stationary member, wherein the axial portion is a radially innermost component of the motor assembly; and

an impeller directly coupled to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis, wherein fluid directed by the impeller exerts a second axial force on the impeller.

2. The motor assembly of claim 1, wherein the first axial force acts on the rotor assembly in a first direction, and wherein the second axial force acts on the impeller in a second direction opposite the first direction.

3. The electric motor assembly of claim 1, wherein the rotor assembly comprises a plurality of permanent magnets and a rotor disk, wherein the rotor disk is directly coupled to the impeller such that the rotor disk contacts the impeller.

4. The electric motor assembly of claim 3, wherein the impeller includes a front plate defining an inlet and an opposing back plate, the back plate being directly coupled to the rotor disk.

5. The electric motor assembly of claim 3, wherein the rotor disk is integrally formed with the impeller.

6. The motor assembly of claim 1, wherein the impeller includes a front plate defining an inlet, an opposing back plate, and a plurality of blades coupled therebetween, wherein the back plate is directly coupled in a face-to-face relationship with the rotor assembly.

7. The motor assembly of claim 1, further comprising a plurality of fasteners configured to couple the rotor assembly to the impeller.

8. The motor assembly of claim 1, wherein the impeller is integrally formed with the rotor assembly.

9. A pump assembly, comprising:

a pump housing;

a motor housing coupled to the pump housing;

a motor assembly, comprising:

a stator assembly; and

a bearing assembly, the bearing assembly comprising:

a stationary member located radially outward of the rotating member, wherein the rotating member includes an axial portion located within an opening of the stationary member, wherein the axial portion is a radially innermost component of the pump assembly; and

10. The pump assembly of claim 9, wherein the rotor assembly comprises a rotor disk and a plurality of permanent magnets, wherein the rotor disk is directly coupled to the impeller such that the rotor disk contacts the impeller.

11. The pump assembly of claim 9, wherein the impeller comprises a front plate defining an inlet, an opposing back plate, and a plurality of blades coupled therebetween, wherein the back plate is directly coupled in a face-to-face relationship with the rotor assembly.

12. The pump assembly of claim 9, wherein the impeller is integrally formed with the rotor assembly.

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

providing a stator assembly;

coupling a rotor assembly to the stator assembly so as to define an axial gap therebetween, wherein the stator assembly exerts a first axial force on the rotor assembly; and

directly coupling a stepped radial portion of a rotating member of a bearing assembly to the rotor assembly such that the stepped radial portion of the rotating member is aligned with two inner surfaces of the rotor assembly along an axis of rotation;

coupling a stationary member to a radially outer side of the rotating member, wherein the rotating member includes an axial portion located within an opening of the stationary member, wherein the axial portion is a radially innermost component of the pump assembly; and

directly coupling an impeller to the rotor assembly opposite the stator assembly such that the rotor assembly and the impeller are configured to rotate about an axis, wherein fluid directed by the impeller is configured to exert a second axial force on the impeller.

14. The method of claim 13, further comprising:

coupling a pump housing to a motor housing;

coupling the stator assembly within the motor housing; and

positioning the rotor assembly and the impeller within the pump housing.

15. The method of claim 13, further comprising modifying a length of the gap to change a magnitude of the first axial force.

16. The method of claim 13, further comprising modifying a speed of the impeller to change a magnitude of the second axial force.

17. The method of claim 13, wherein directly coupling the impeller to the rotor assembly comprises directly coupling a rotor disk of the rotor assembly to the impeller such that the rotor disk is in contact with the impeller.

18. The method of claim 13, wherein directly coupling the impeller to the rotor assembly comprises coupling a back plate of the impeller in a face-to-face relationship with the rotor assembly.

19. The method of claim 13, wherein directly coupling the impeller to the rotor assembly comprises integrally forming the impeller with the rotor assembly.