Axial flux motor having a mechanically independent stator

Abstract

An axial flux motor comprising a stator housing containing a plurality of stator cores attached to a yoke, each stator having an electrical winding, a rotor housing coupled to a shaft by at least one bearing, and a rotor assembly having a plate coupled to the shaft and a plurality of magnets coupled to the plate, the rotor assembly configured to be coupled to the rotor assembly of a first configuration and the rotor assembly of a second configuration without modification.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to axial flux motors that can be used in many applications without significant modification. More particularly, embodiments of the present invention contemplate an axial flux motor having a mechanically independent modular stator assembly configured to receive various rotor assembly structures.

Background Art

[0002] Those skilled in the art will understand that axial flux motors are often used in pumps that use impellers and other rotating elements configured to move water, oil, and other fluids. Axial flux motors are also used to rotate fans, electronic storage media, etc. One advantage of using an axial flux motor is its size, which can be very easily scaled up or down. In fact, the components of a brushless DC motor are often directly incorporated onto a printed circuit board.

[0003] An axial flux motor generally consists of a stator spaced apart from the rotor. As the name indicates, "axial" refers to the fact that the air gap between the stator and the rotor is aligned or parallel to the axis of rotation of the rotor. The stator is typically an electromagnet formed from a conductor wound around one or more cores, often made of metal. A housing houses the stator. The rotor uses one or more permanent magnets. In operation, exciting the electromagnet, or passing a current through it, generates a constant or variable magnetic field that interacts with the magnetic field of the permanent magnets of the rotor. Selective changes in the polarity of the magnetic field cause the rotor to rotate. The rotor is connected to a shaft that is connected to the blades of an impeller, gears, a fan, etc.

[0004] Integrating a brushless DC motor into a vehicle often requires a great deal of effort. For example, when adopting an existing DC motor in a vehicle, it is often necessary to modify the motor's stator housing. The internal elements of the stator also require costly and time-consuming modifications. More specifically, a brushless DC motor is usually an integrated unit, and the stator assembly, rotor assembly, control board, and each housing are configured as a single unit. Therefore, changes in motor applications inevitably require design changes to the housing and internal elements, which leads to an increase in the price of the elements and the lead time.

[0005] Some automotive applications of axial flux motors include internal combustion engines that require fluids, particularly coolant circulation pumps, or pumps for pumping coolant in other applications.

[0006] A representative of this technology is US Patent Application No. 2015 / 0030479, which discloses a wet rotor pump having an axial flux motor. The rotor of the impeller is disposed in the wet region, while the stator is disposed in the dry region. The rotor is formed by one or more samarium cobalt (SmCo) permanent magnets.

[0007] The representative technology further includes US Patent Application No. 2017 / 0016449, which discloses a pump comprising a housing that partially defines a cavity, an impeller disposed within the cavity, the impeller including a first disk and vanes disposed on the first disk, the impeller being rotatable about a rotation axis, a first stator core disposed in the housing, windings disposed on the first stator core, and a first inlet defined by the housing, wherein the first inlet, the impeller, and the housing define a fluid flow path.

[0008] Providing an axial flux motor having a modular element configured to receive a number of rotor assemblies with a standard stator assembly has been a long-felt need.

[0009] One feature of some embodiments of the present invention is to provide an axial flux motor comprising a stator assembly and a rotor assembly. The rotor assembly comprises a rotor having a plurality of permanent magnets connected to a rotor housing via at least one bearing. The rotor may have an integrated shaft for connection to a fan or an impeller. Alternatively, the rotor is operatively connected to a shaft that receives the fan or the rotor. The housing of the rotor assembly is configured to receive additional elements such as nozzles or turbines associated with the role of a water pump, an oil pump, etc. The housing of the rotor assembly also includes a flange that is selectively connected to a corresponding flange of the stator assembly. The stator assembly houses a stator consisting of a stator core wound with windings to form an electromagnet. The magnetic force of the stator interacts with the magnetic field of the permanent magnets to impart rotation to the rotor.

[0010] Those skilled in the art will recognize that the stator assembly and the rotor assembly must be arranged in proximity to each other for the motor to operate properly. Providing a modular stator assembly that can be used in a number of applications is one feature of embodiments of the present invention. Embodiments of the present invention are mainly directed to a modular and mechanically independent stator assembly having an integrated circuit board. The associated rotor is incorporated into an application-specific housing regardless of the application of the stator assembly. Then, application-specific software will be supplied to the integrated circuit board. Further, the intended stator assembly of some embodiments has no moving parts such as a shaft, for example, and the interaction between the stator assembly and an application-specific rotor assembly connected thereto is transmitted only by magnetic force. The drawings shown in more detail below show a stator assembly used in applications of oil and water pumps.

[0011] As used herein, the term "one" thing refers to one or more things. Accordingly, the terms "one", "one or more" and "at least one" are used interchangeably herein. Further, the expressions "at least one", "one or more" and "and / or" are unrestricted expressions that are conjunctive and disjunctive in operation, as used herein. For example, "at least one of A, B and C", "at least one of A, B or C", "one or more of A, B and B", "one or more of A, B or C" and "A, B and / or C" mean only A, only B, only C, A and B, A and C, B and C, or A, B and C.

[0012] Unless otherwise indicated, all numerical values indicating amounts, sizes, conditions, etc. used in this specification and the drawings should be understood as approximations that may be modified in all instances in accordance with the requirements for a particular application of the novel assemblies and methods described herein.

[0013] The use of "comprising", "including" or "having" and variations thereof means including the items recited hereinafter and their equivalents as well as additional items. Accordingly, the terms "comprising", "including" or "having" and variations thereof are used interchangeably herein.

[0014] The term "means" as used in this specification should be construed as broadly as possible in accordance with 35 U.S.C. § 112(f). Accordingly, the term "means" includes all structures, materials or acts described herein, and all of their equivalents. Further, the structures, materials or acts and their equivalents include all that are described in the summary, brief description of the drawings, detailed description and the appended drawings.

[0015] The summary of the present invention is not intended to be, nor should it be construed as, a representative of a sufficiently broad scope of the present invention. That is, these and other features and advantages are apparent from the disclosure of the invention described herein. Further, the above-described embodiments, features, objects, and structures are neither complete nor exhaustive. As will be understood, other embodiments of the present invention may be used alone or in combination with one or more of the features described above or below. Still further, references made to "the present invention" or its features should be understood to refer to an embodiment of the present invention and should not necessarily be construed as limiting all embodiments to a particular description. The present invention, like the accompanying drawings and detailed description, is described at various levels of detail, and limitations as to the scope of the present invention are not intended in this summary of the invention by whether or not elements etc. are included. Additional features of the present invention will become more readily apparent from the detailed description, particularly when taken in conjunction with the drawings.

Brief Description of the Drawings

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the general description of the present invention described above and the detailed description of the drawings given below, explain the principles of the present invention.

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[0017] It should be understood that the drawings do not necessarily show size. In some examples, details showing other details that are not necessary for understanding the present invention or are difficult to understand are omitted. Of course, the present invention is not necessarily limited to the specific embodiments described herein.

Mode for Carrying Out the Invention

[0018] FIGS. 1 to 11 show an axial flux motor 2 comprising a stator assembly 6 connected to a rotor assembly 10. The stator assembly 6 of the embodiment of the present invention is of a modular type capable of receiving rotor assemblies 10 of various structures. For example, the illustrated stator assembly can receive a rotor assembly configured to be used in an oil pump or a water pump. Those skilled in the art will understand a stator assembly intended to be able to receive other rotor assemblies.

[0019] Figs. 2 and 3 are cross-sectional views showing the stator assembly of Fig. 1. The stator assembly 6 includes a stator housing 14 that houses a stator 15 composed of a plurality of electromagnets. More specifically, the stator 15 consists of a yoke 16 that receives an electric winding 22 and has a plurality of cores 18 extending therefrom. The wound cores form magnetic poles. The cores may be in a prism shape having a substantially triangular cross-section. Well-known thermal potting may be used in the stator housing that covers the stator. The thermal potting cools the axial flux motor by providing reliable heat dissipation means from the stator and the stator housing. Heat is generally generated by iron loss, copper loss, and resistive heat from eddy currents induced in the stator and windings by a changing magnetic field, or from a coolant that is pumped (when applied to a water pump) and led to the housing from an engine block (when applied to an automobile) or other usage environment (not shown). Again, a feature of some embodiments of the present invention is to provide a stator assembly 6 that allows for rotor assemblies of various configurations and functions together.

[0020] The power control electronics 23 is provided within an electronics housing 24 associated with the stator housing 14. The power electronics can control the shaft rotation speed and detect defects. The electronics housing also houses a control unit configured to selectively control the amount and characteristics of the electricity passing through the windings to generate a magnetic field within the electromagnet. The control method may be PWM, LIN protocol / bus, or CAN protocol / bus. The LIN bus is a sub-bus system based on a serial communication protocol. The bus is a single master / multiple slave bus that uses a single communication line to transmit data. The controller area network, i.e., the CAN protocol, is a communication method between various electronic devices mounted on a vehicle, such as an engine management system, water pump, oil pump, active suspension, ABS, gear control, lighting control, air conditioning, airbag, and central locking. PWM, i.e., pulse width modulation, is a type of digital signal used in various applications including control circuits. The housing also includes a heat sink 26 designed to dissipate the heat generated by the stator. The connector is used for electrical communication with a control unit such as a power source.

[0021] Figures 6 and 7 are components of a stator well known to those skilled in the art. Again, the stator core forms a yoke 16 having a plurality of cores 18 extending therefrom. The winding coils 22 consist of a plurality of, for example, six coils arranged on each core 18. The windings are windings having a circular or flat cross-section. The flat wire has a square or rectangular cross-section. The flat wire or round wire is made of copper or aluminum. The winding surface extends perpendicular to the shaft axis, and thus the magnetic flux extends axially. The motor of one embodiment uses a 6-pole stator and has a rated power of approximately 120W to 250W. Other embodiments use a 9-pole or 15-pole stator and generate approximately 400W to 1200W and 1500W to 3500W, respectively. In fact, in some embodiments of the present invention, the magnetic poles of the stator are shortened in the longitudinal direction so that the coils of the stator are incorporated into a printed circuit board.

[0022] The inner volume of the stator assembly including the central portion of the core accommodates at least one wire extending therethrough. The inner volume of the stator assembly including the central portion of the core may be filled with insulating resin. Thus, the stator assembly has a stator with a substantially closed inner volume. One skilled in the art will understand that the shown coil prevents the use in a shaft stator as conventionally found in many brushless DC motors. Also, the intended stator assembly in some embodiments has no moving parts such as, for example, a shaft or bearings. The rotor shaft does not enter into the stator housing, i.e., does not penetrate the stator. The interaction between the stator assembly and the associated application-specific rotor assembly is driven solely via magnetic force. In other words, the rotor is completely housed within the rotor housing, the shaft does not extend across the boundary between the rotor housing and the stator housing, and the stator is completely housed within the stator housing.

[0023] In one embodiment, a conventional 3D Hall effect position sensor is disposed at the center (i.e., substantially corresponding to the longitudinal axis of the yoke) and connected to the motor control circuit. The intended Hall effect sensor is designed to shorten the start-up time of the motor and is embedded in the above-described filled resin with the detection surface exposed to the rotor side. One skilled in the art will understand that the Hall effect sensor functions by detecting the direction of the magnetic field from the rotor. Thus, the rotor has one of the extended magnets or additional magnets are used to generate the position detection magnetic field.

[0024] FIG. 8 shows a rotor assembly 10 used within the axial flux motor of FIG. 1. The rotor assembly comprises a housing 50 that houses a shaft 54 connected to the housing by at least one bearing 58. The bearing 58 may be an integral bearing in which the shaft 54 has an inner race of the bearing. Further, the bearing may be a two-row ball bearing or a two-row ball-roller bearing. The intended roller bearing may be a cylindrical or tapered roller. The use of a single-row bearing is made possible by the shortened length of the pump shaft provided by the configuration of the axial flux motor in one embodiment.

[0025] The shaft is connected to a plate 62 that houses a plurality of rotor magnets 66. The plurality of magnets may be ring-shaped magnets having poles around the perimeter, or a plurality of individual magnets having poles in alternating positions. The magnets may be ferrite, rare earth, or other known materials. The magnets are adhered to the poles using known methods. For example, permanent magnets may be adhered to the plate. Those skilled in the art will understand that in some instances, permanent magnets are fixed to the plate by an adhesive, but other connection methods such as press-fitting, welding, etc. are available.

[0026] In an alternative manufacturing method, the rotor is manufactured by a sintering process in which a powder material containing a magnetic material is compressed in a mold and heated to form the rotor. The magnets are then guided to the rotor to create magnetization regions in the rotor that generate a permanent magnetic field. An example of this manufacturing process is discussed in U.S. Provisional Patent Application No. 62 / 959,010 (reference number O19-056), which is incorporated herein by reference.

[0027] The gap formed between the rotor and the stator in one embodiment ranges from 0.2 mm to 1.5 mm. The gap is preferably as small as possible to achieve the maximum magnetic effect. The flange 70 may be used to connect the rotor assembly 10 to the complementary flange 74 of the stator assembly (see, for example, FIG. 3). In operation, the magnetic field generated by the stator interacts with the magnetic field of the magnets 66 of the rotor to rotate the shaft, for example, to operate a pump.

[0028] FIGS. 9 - 11 show an axial flux motor 102 of another embodiment of the present invention incorporated into a water pump. Here, the stator assembly 106 has the same configuration as shown in FIG. 2. However, the rotor assembly 110 is slightly different and is configured to act as a water pump having an inlet 180 and an outlet 184. The plate 162 of one embodiment of the present invention is connected to the shaft 154 and to the impeller 188. In operation, the impeller rotates to move fluid from the inlet to the outlet, which will be understood by those skilled in the art. It is important that the elements of the stator assembly 106 are the same as in the embodiment shown in FIG. 1.

[0029] Typical characteristics of embodiments of the present invention have been described. However, to avoid unnecessarily obscuring the embodiments of the present invention, the above description omits known devices, methods, systems, structures, and / or devices understood by those skilled in the art that are commonly included in embodiments of the present invention. Such omissions should not be construed as limitations on the scope of the invention as recited in the claims. Specific details are provided to give an understanding of some embodiments of the present invention. However, embodiments of the present invention may be implemented in various ways that go beyond the specific details described herein.

[0030] Modifications and variations of the various embodiments of the invention described in this specification will occur to those skilled in the art. It should be clearly understood that such modifications and variations are within the spirit and scope of the invention as set forth in the claims described hereinafter. Further, it should be understood that the invention described in this specification is not limited to the details of the structures or the configurations of the elements shown in the above description or drawings. That is, the embodiments of the invention described in this specification can be realized and implemented in various forms. The scope of the various embodiments described in this specification is indicated by the following claims rather than by the above description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within the scope of the claims. It is intended to obtain the right to include alternative embodiments within the scope of the claims, including alternative exchanges and / or equivalent structures, functions, ranges or steps, within the permitted scope, regardless of whether such alternative, interchangeable and / or equivalent structures, functions, ranges or steps are disclosed in this specification, and without intending to publicly provide patentable subject matter.

[0031] The above disclosure is not intended to limit the present invention to the forms disclosed herein. For example, in the above detailed description, various features of the present invention are classified together with one or more embodiments for the purpose of streamlining the disclosure. The method of disclosure should not be construed as reflecting an intention to claim more features than are clearly recited in the invention as set forth in the claims. Rather, as the following claims will show, the features of the invention are fewer than all the features of one of the disclosed embodiments described above. Accordingly, the following claims are incorporated into the detailed description of the invention while each claim stands on its own as a separate preferred embodiment of the invention. Further, the embodiments of the present invention described in this specification include various sub-combinations and subsets, including elements, methods, steps, systems and / or apparatuses substantially as shown and described in this specification. Thus, those skilled in the art will understand that it is possible to provide some features of the embodiments of the present invention without providing others. In other words, one or more aspects, features, elements, means or embodiments described in this specification may be combined with one or more other aspects, features, elements, means or embodiments described in this specification.

Claims

1. A stator assembly having a stator housing that houses a plurality of stator cores attached to a yoke, each stator having an electrical winding, a rotor assembly having a rotor housing connected to a shaft by at least one bearing, a plate connected to the shaft, and a plurality of magnets connected to the plate, the stator assembly is configured to be connected to a rotor assembly of a first configuration and a rotor assembly of a second configuration without modification, and the internal volume of the stator assembly houses at least one wire extending radially therethrough, and the at least one wire passes through the axis of the internal volume, an axial flux motor characterized by this.

2. The axial flux motor according to claim 1, wherein the rotor assembly of the first configuration is associated with an oil pump, the rotor assembly of the second configuration is associated with a water pump, and the shaft is connected to an impeller.

3. The axial flux motor according to claim 1, wherein the stator housing has a flange that engages a flange of the rotor housing.

4. The axial flux motor according to claim 1, wherein the stator has a plurality of prism-shaped cores that receive corresponding stator coils.

5. The axial flux motor according to claim 1, wherein the electrical winding comprises a flat wire.

6. The axial flux motor according to claim 1, wherein the electrical winding comprises a round wire.

7. The axial flux motor according to claim 1, wherein the stator assembly includes an integrated circuit board.

8. The axial flux motor according to claim 1, wherein the stator assembly and the rotor assembly are not mechanically connected.

9. The axial flux motor according to claim 1, wherein the stator assembly does not include a movable part.

10. The axial flux motor according to claim 1, wherein the stator assembly has a stator having a substantially closed internal volume.

11. The axial flux motor according to claim 1, wherein the shaft is completely housed within the rotor housing, the shaft does not extend across the boundary portion between the rotor housing and the stator housing, and the stator is completely housed within the stator housing.

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