Power tools including axial FLUX motors

Abstract

A power tool including a battery pack interface and an axial flux motor. The battery pack interface is configured to receive a removable and rechargeable battery pack. The axial flux motor includes a stator and a rotor. The stator includes a stator core composed of soft magnetic composite material or electrical steel (e.g., laminated or solid steel) and a plurality of winding coils. The rotor is configured to rotate with respect to the stator. The rotor includes a rotor core composed of soft magnetic composite material or electrical steel (e.g., laminated or solid steel) and a plurality of permanent magnets forming a plurality of permanent magnet poles.

Description

Attorney Docket No. 066042- 1891 -WOO 1POWER TOOLS INCLUDING AXIAL FLUX MOTORSRELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 686,411, filed Aug. 23, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] Embodiments described herein relate to motors for use in a power tool and / or outdoor power equipment.SUMMARY

[0003] Axial flux motors (“AFMs”) have only been used in low speed and high torque applications, such as cooling and heat dissipation systems, the automotive industry, and robotics.

[0004] Power tools described herein include a battery pack interface and an axial flux motor. The battery pack interface is configured to receive a removable and rechargeable battery pack. The axial flux motor includes a stator and a rotor. The stator includes a stator core composed of soft magnetic composite material and a plurality of winding coils. The rotor is configured to rotate with respect to the stator. The rotor includes a rotor core and a plurality of permanent magnets forming a plurality of permanent magnet poles.

[0005] Power tools described herein include a battery pack interface and an axial flux motor. The axial flux motor includes a stator and a rotor. The stator includes a stator core made of soft magnetic composite material and a plurality of winding coils. The rotor is configured to rotate with respect to the stator. The rotor includes: a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles. A magnetic flux path crosses between the stator and the rotor in a direction parallel to an axis of rotation of the rotor.

[0006] Power tools described herein include a battery pack interface and an axial flux motor. The axial flux motor includes a first stator a first rotor, and a second rotor. The first stator includes a stator core made of soft magnetic composite material and a plurality of winding coils. A first rotor and a second rotor are configured to rotate with respect to the first stator. The first rotor and the second rotor each includes a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles. A magnetic flux path crosses between the firstAttorney Docket No. 066042- 1891 -WOO 1 rotor, the first stator, and the second rotor in a direction parallel to an axis of rotation of the first rotor.

[0007] Power tools described herein include a battery pack interface and an axial flux motor. The axial flux motor includes a first stator, a second stator, and a rotor. The first stator and a second stator each includes a plurality of winding coils. The first rotor is configured to rotate with respect to the first stator. The first rotor and includes a rotor core and a plurality of permanent magnets forming a plurality of permanent magnet poles. A magnetic flux path crosses between the first stator, the first rotor, and the second stator in a direction parallel to an axis of rotation of the first rotor.

[0008] Before any embodiments are explained in detail, it is to be understood that the embodiments are not limited in application to the details of the configurations and arrangements of components set forth in the following description or illustrated in the accompanying drawings. The embodiments are capable of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings.

[0009] Unless the context of their usage unambiguously indicates otherwise, the articles “a,” “an,” and “the” should not be interpreted as meaning “one” or “only one.” Rather these articles should be interpreted as meaning “at least one” or “one or more.” Likewise, when the terms “the” or “said” are used to refer to a noun previously introduced by the indefinite article “a” or “an,” “the” and “said” mean “at least one” or “one or more” unless the usage unambiguously indicates otherwise.

[0010] In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic-based aspects mayAttorney Docket No. 066042- 1891 -WOO 1 be implemented in software (e.g., stored on non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and / or application specific integrated circuits (“ASICs”). As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components, may be utilized to implement the embodiments. For example, “servers,” “computing devices,” “controllers,” “processors,” etc., described in the specification can include one or more processing units, one or more computer-readable medium modules, one or more input / output interfaces, and various connections (e.g., a system bus) connecting the components.

[0011] Relative terminology, such as, for example, “about,” “approximately,” “substantially,” etc., used in connection with a quantity or condition would be understood by those of ordinary skill to be inclusive of the stated value and has the meaning dictated by the context (e.g., the term includes at least the degree of error associated with the measurement accuracy, tolerances [e.g., manufacturing, assembly, use, etc.] associated with the particular value, etc.). Such terminology should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4”. The relative terminology may refer to plus or minus a percentage (e.g., 1%, 5%, 10%) of an indicated value.

[0012] It should be understood that although certain drawings illustrate hardware and software located within particular devices, these depictions are for illustrative purposes only. Functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Likewise, functionality performed by multiple components may be consolidated and performed by a single component. In some embodiments, the illustrated components may be combined or divided into separate software, firmware and / or hardware. For example, instead of being located within and performed by a single electronic processor, logic and processing may be distributed among multiple electronic processors. Regardless of how they are combined or divided, hardware and software components may be located on the same computing device or may be distributed among different computing devices connected by one or more networks or other suitable communication links. Similarly, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is “configured” in aAttorney Docket No. 066042- 1891 -WOO 1 certain way is configured in at least that way but may also be configured in ways that are not explicitly listed.

[0013] Accordingly, in the claims, if an apparatus, method, or system is claimed, for example, as including a controller, control unit, electronic processor, computing device, logic element, module, memory module, communication channel or network, or other element configured in a certain manner, for example, to perform multiple functions, the claim or claim element should be interpreted as meaning one or more of such elements where any one of the one or more elements is configured as claimed, for example, to make any one or more of the recited multiple functions, such that the one or more elements, as a set, perform the multiple functions collectively.

[0014] Other aspects of the embodiments will become apparent by consideration of the detailed description and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 illustrates a perspective view of a power tool, according to some embodiments.

[0016] FIG. 2 illustrates a block diagram of a control system of the power tool of FIG. 1, according to some embodiments.

[0017] FIG. 3 illustrates a battery pack for use with the power tool of FIG. 1, according to some embodiments.

[0018] FIG. 4 illustrates a block diagram of a control system of the battery pack of FIG. 3, according to some embodiments.

[0019] FIG. 5 illustrates an axial flux motor, according to some embodiments.

[0020] FIG. 6 illustrates an axial flux motor, according to some embodiments.

[0021] FIG. 7 illustrates an axial flux motor, according to some embodiments.

[0022] FIG. 8 illustrates an axial flux motor with a dual rotor configuration, according to some embodiments.

[0023] FIG. 9 illustrates an axial flux motor with a dual rotor configuration, according to some embodiments.Attorney Docket No. 066042- 1891 -WOO 1

[0024] FIG. 10 illustrates an axial flux motor with a dual rotor configuration, according to some embodiments.

[0025] FIG. 11 illustrates an axial flux motor with a dual stator configuration, according to some embodiments.

[0026] FIG. 12 illustrates a multistage axial flux motor, according to some embodiments.

[0027] FIG. 13 illustrates a multistage axial flux motor, according to some embodiments.DETAILED DESCRIPTION

[0028] FIG. 1 illustrates a power tool 100 including a permanent magnet motor. The power tool 100 is, for example, a hammer drill including a housing 102. The housing 102 includes a handle portion 104 and motor housing portion 106. The power tool 100 further includes an output driver 108 (illustrated as a chuck), a trigger 110, and a battery pack interface 112. The battery pack interface 112 is configured to mechanically and electrically connect to or receive a power tool battery pack. Although FIG. 1 illustrates a hammer drill, in some embodiments, the components described herein are incorporated into other types of power tools including drilldrivers, impact drivers, impact wrenches, angle grinders, circular saws, reciprocating saws, plate compactors, core drills, string trimmers, leaf blowers, vacuums, and the like. In a permanent magnet motor power tool, such as power tool 100, switching elements are selectively enabled and disabled by control signals from a controller to selectively apply power from a power source (e g., a battery pack) to drive a permanent magnet motor.

[0029] FIG. 2 illustrates a control system 200 for the power tool 100. The control system 200 includes a controller 202. The controller 202 is electrically and / or communicatively connected to a variety of modules or components of the power tool 100. For example, the illustrated controller 202 is electrically connected to a motor 204, a battery pack interface 206, a trigger switch 208 (connected to a trigger 210), one or more sensors or sensing circuits 212, one or more indicators 214, a user input module 216, a power input module 218, an inverter bridge or FET switching module 220 (e.g., including a plurality of switching FETs), and gate drivers 224 for driving the FET switching module 220. In some embodiments, motor 204 is a permanent magnet motor. The controller 202 includes combinations of hardware and software that areAttorney Docket No. 066042- 1891 -WOO 1 operable to, among other things, control the operation of the power tool 100, monitor the operation of the power tool 100, activate the one or more indicators 214 (e.g., an LED), etc.

[0030] The controller 202 includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 202 and / or the power tool 100. For example, the controller 202 includes, among other things, a processing unit 226 (e.g., a microprocessor, a microcontroller, an electronic controller, an electronic processor, or another suitable programmable device), a memory 228, input units 230, and output units 232. The processing unit 226 includes, among other things, a control unit 234, an arithmetic logic unit (“ALU”) 236, and a plurality of registers 238, and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 226, the memory 228, the input units 230, and the output units 232, as well as the various modules or circuits connected to the controller 202 are connected by one or more control and / or data buses (e.g., common bus 240). The control and / or data buses are shown generally in FIG. 2 for illustrative purposes. The use of one or more control and / or data buses for the interconnection between and communication among the various modules, circuits, and components would be known to a person skilled in the art in view of the embodiments described herein.

[0031] The memory 228 is a non-transitory computer readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, such as a ROM, a RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. The processing unit 226 is connected to the memory 228 and executes software instructions that are capable of being stored in a RAM of the memory 228 (e.g., during execution), a ROM of the memory 228 (e.g., on a generally permanent basis), or another non-transitory computer readable medium such as another memory or a disc. Software included in the implementation of the power tool 100 can be stored in the memory 228 of the controller 202. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 202 is configured to retrieve from the memory 228 and execute, among other things, instructions related to the control processes and methods described herein. In other constructions, the controller 202 includes additional, fewer, or different components.Attorney Docket No. 066042- 1891 -WOO 1

[0032] The battery pack interface 206 includes a combination of mechanical components (e.g., rails, grooves, latches, etc.) and electrical components (e.g., one or more terminals) configured to and operable for interfacing (e.g., mechanically, electrically, and communicatively connecting) with a battery pack. For example, power provided by a battery pack 300 (see FIG. 3) to the power tool 100 is provided through the battery pack interface 206 to the power input module 218. The power input module 218 includes combinations of active and passive components to regulate or control the power received from the battery pack 300 prior to power being provided to the controller 202. The battery pack interface 206 also supplies power to the FET switching module 220 to be switched by the switching FETs to selectively provide power to the motor 204. The battery pack interface 206 also includes, for example, a communication line 242 for providing a communication line or link between the controller 202 and the battery pack 300.

[0033] The sensor circuits 212 include one or more current sensors, one or more speed sensors, one or more Hall effect sensors, one or more temperature sensors, etc. The indicators 214 include, for example, one or more light-emitting diodes (“LEDs”). The indicators 214 can be configured to display conditions of, or information associated with, the power tool 100. For example, the indicators 214 are configured to indicate measured electrical characteristics of the power tool 100, the status of the power tool, the status the motor 204, etc. The user input module 216 is operably coupled to the controller 202 to, for example, select a forward mode of operation or a reverse mode of operation, a torque and / or speed setting for the power tool 100 (e.g., using torque and / or speed switches), etc. In some embodiments, the user input module 216 includes a combination of digital and analog input or output devices required to achieve a desired level of operation for the power tool 100, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc.

[0034] FIG. 3 illustrates a battery pack 300. The battery pack 300 includes a housing 302 and an interface portion 304 for connecting the battery pack 300 to a power tool, such as the power tool 100.

[0035] FIG. 4 illustrates a control system for the battery pack 300. The control system includes a controller 400. The controller 400 is electrically and / or communicatively connected to a variety of modules or components of the battery pack 300. For example, the illustratedAttorney Docket No. 066042- 1891 -WOO 1 controller 400 is connected to one or more battery cells 402 and an interface 404 (e g., the interface portion 304 of the battery pack 300 illustrated in FIG. 3). The controller 400 is also connected to one or more voltage sensors or voltage sensing circuits 406, one or more current sensors or current sensing circuits 408, and one or more temperature sensors or temperature sensing circuits 410. The controller 400 includes combinations of hardware and software that are operable to, among other things, control the operation of the battery pack 300, monitor a condition of the battery pack 300, enable or disable charging of the battery pack 300, enable or disable discharging of the battery pack 300, etc.

[0036] The controller 400 includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 400 and / or the battery pack 300. For example, the controller 400 includes, among other things, a processing unit 412 (e.g., a microprocessor, a microcontroller, an electronic processor, an electronic controller, or another suitable programmable device), a memory 414, input units 416, and output units 418. The processing unit 412 includes, among other things, a control unit 420, an ALU 422, and a plurality of registers 424, and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 412, the memory 414, the input units 416, and the output units 418, as well as the various modules or circuits connected to the controller 400 are connected by one or more control and / or data buses (e.g., common bus 426). The control and / or data buses are shown generally in FIG. 4 for illustrative purposes. The use of one or more control and / or data buses for the interconnection between and communication among the various modules, circuits, and components would be known to a person skilled in the art in view of the embodiments described herein.

[0037] The memory 414 is a non-transitory computer readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include combinations of different types of memory, such as a ROM, a RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, a hard disk, an SD card, or other suitable magnetic, optical, physical, or electronic memory devices. The processing unit 412 is connected to the memory 414 and executes software instructions that are capable of being stored in a RAM of the memory 414 (e.g., during execution), a ROM of the memory 414 (e g., on a generally permanent basis), or another non-transitory computer readable medium such as another memoryAttorney Docket No. 066042- 1891 -WOO 1 or a disc. Software included in the implementation of the battery pack 300 can be stored in the memory 414 of the controller 400. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 400 is configured to retrieve from the memory 414 and execute, among other things, instructions related to the control processes and methods described herein. In other constructions, the controller 400 includes additional, fewer, or different components.

[0038] The interface 404 includes a combination of mechanical components (e.g., rails, grooves, latches, etc.) and electrical components (e.g., one or more terminals) configured to and operable for interfacing (e.g., mechanically, electrically, and communicatively connecting) the battery pack 300 with another device (e.g., a power tool, a battery pack charger, etc.). For example, the interface 404 is configured to communicatively connect to the controller 400 via a communications line 428.

[0039] FIG. 5 illustrates an axial flux motor 500 for use in the power tool 100. The axial flux motor 500 has an axis of rotation 502. A stator 504 is configured to receive a plurality of stator windings 508 (e.g., winding coils). A plurality of permanent magnets 506 is located on a rotor 505 between to the stator 504 and the rotor 505. The plurality of permanent magnets 506 form a plurality of permanent magnet poles on the rotor 505. The rotor 505 and the plurality of permanent magnets 506 are connected to the rotor 505 and rotate with respect to the stator 504. The stator 504, the plurality of permanent magnets 506, and the rotor 505 work in conjunction to allow magnetic flux to flow along a magnetic flux path 512. Additionally, the stator windings 508 provide a current path 510 for the electrical current in the axial flux motor 500. The rotor 505 is positioned adjacent to the stator 504 in the axial direction of the axial flux motor 500. An airgap 514 is formed between and separates the stator 504 and the rotor 505. The magnetic flux path 512 crosses the airgap 514 in a direction parallel to the axis of rotation 502.

[0040] FIG. 6 illustrates a stator and rotor assembly for an axial flux motor 600 (e.g., axial flux motor 500). The motor 600 also has a length, “L”, and a diameter, “D”. For an axial flux motor, the relationship between the diameter, D, of the motor 600 and the length, L, of the motor is of particular importance. Specifically, when compared to a standard radial flux motor, an axial flux motor will generate a higher torque density when the length of the motor 600 is less than about 0.4D (i.e., 0.4 times the diameter of the motor 600) for a single-stage motor and less thanAttorney Docket No. 066042- 1891 -WOO 1 about 0.6D for a multi-stage motor. For a range of motor diameters between 25 millimeters (“mm”) and 150 mm with the single-stage stator and rotor assembly, the lengths of the motor should be less than 10 mm (25 mm diameter) or less than 60 mm (150 mm diameter). For a multi-stage motor, the lengths of the motor should be less than 15 mm (25 mm diameter) or less than 90 mm (150 mm diameter). Using this relationship between motor length and motor diameter can be used to select, for example, which types of power tools or equipment are preferred for use with axial flux motors. Power tools that have a ratio of motor length to motor diameter of less than 0.4 (for single-stage motor) and less than 0.6 (for multi-stage motor) are suitable for use with an axial flux motor. These tools can include power tools such as impact wrenches, reciprocating saws, pruning shears, demolition breakers, core drills, etc. As the ratio of motor length to motor diameter increases, power tools become less suitable for use with axial flux motors. For example, certain grinders, multitools, and ratchets have a ratio of motor length to motor diameter greater than approximately 0.6, which makes them less suitable for use with axial flux motors.

[0041] FIG. 7 illustrates an axial flux motor 700 for use with the power tool 100. The axial flux motor 700 is configured to have a single airgap 701 between a stator 702 and a rotor 703. The axial flux motor 700 is configured to allow magnetic flux to travel along a magnetic flux path 704. The magnetic flux crosses the airgap 701 in a direction parallel to an axis of rotation 705 of the axial flux motor 700. The magnetic flux path 704 intersects a plurality of permanent magnets 706 positioned on the rotor 703. The plurality of permanent magnets 706 form a plurality of permanent magnet poles on the rotor 703. The rotor 703 is configured to rotate about the axis of rotation 705 with respect to the stator 702. The stator 702 includes a plurality of stator windings 708. The stator windings 708 are configured to be selectively energized to cause rotation of the rotor 703 about the axis or rotation 705. The single airgap axial flux motor 700 provides for easier manufacturing, but produces less torque than other forms of axial flux motors.

[0042] FIG. 8 illustrates an axial flux motor 800 for use with the power tool 100. The axial flux motor 800 includes a first rotor 802 and a second rotor 804. The first rotor 802 and the second rotor 804 are configured to rotate about an axis of rotation 806. The axial flux motor 800 also includes a stator 808 (e.g., a slotted stator core). The stator 808 is positioned between the first rotor 802 and the second rotor 804, and a first airgap 810 and a second airgap 812 are formed on either side of the stator 808. The stator 808 includes a plurality of stator windings 814Attorney Docket No. 066042- 1891 -WOO 1 that are wound around the slotted stator core (e.g., oriented circumferentially). Tn some embodiments, the stator 808 is made of steel laminations. In other embodiments, the stator 808 is made of a soft magnetic composite (“SMC”) material. The first rotor 802 and the second rotor 804 each include a plurality of permanent magnets 816. The plurality of permanent magnets 816 form a plurality of permanent magnet poles on the first rotor 802 and the second rotor 804. The first rotor 802 and the second rotor 804 are configured to rotate with respect to the stator 808 and about the axis of rotation 806. The stator windings 814 are configured to be selectively energized to cause rotation of the first rotor 802 and second rotor 804 about the axis or rotation 806. The axial flux motor 800 is configured to allow magnetic flux to travel along a magnetic flux path 818. The magnetic flux crosses the first airgap 810 and the second airgap 812 in a direction parallel to an axis of rotation 806 of the axial flux motor 800. The flux path 818 intersects the plurality of permanent magnets 816 positioned on the first rotor 802 and the second rotor 804. The double airgap double rotor axial flux motor 800 provides for maximum torque among axial flux motor designs.

[0043] FIG. 9 illustrates an axial flux motor 900 for use with the power tool 100. The axial flux motor 900 includes a first rotor 902 and a second rotor 904. The first rotor 902 and the second rotor 904 are configured to rotate about an axis of rotation 906. The axial flux motor 900 also includes a stator 908 (e.g., a slotted stator core). The stator 908 is positioned between the first rotor 902 and the second rotor 904, and a first airgap 910 and a second airgap 912 are formed on either side of the stator 908. The stator 908 includes a plurality of stator windings 914 that are wound around the stator (e.g., oriented radially). In some embodiments, the stator 908 is made of steel laminations. In other embodiments, the stator 908 is made of an SMC material. The first rotor 902 and the second rotor 904 each include a plurality of permanent magnets 916. The plurality of permanent magnets 916 form a plurality of permanent magnet poles on the first rotor 902 and the second rotor 904. The first rotor 902 and the second rotor 904 are configured to rotate with respect to the stator 908 and about the axis of rotation 906. The stator windings 914 are configured to be selectively energized to cause rotation of the first rotor 902 and the second rotor 904 about the axis or rotation 906. The axial flux motor 900 is configured to allow magnetic flux to travel along a magnetic flux path 918. The magnetic flux crosses the first airgap 910 and the second airgap 912 in a direction parallel to an axis of rotation 906 of the axial flux motor 900. The flux path 918 intersects the plurality of permanent magnets 916 positionedAttorney Docket No. 066042- 1891 -WOO 1 on the first rotor 902 and the second rotor 904. The double airgap double rotor radially-wound axial flux motor 900 provides for higher torque than a single airgap axial flux motor design and offers improved mechanical robustness.

[0044] FIG. 10 illustrates an axial flux motor 1000 for use with the power tool 100. The axial flux motor 1000 includes a first rotor 1002 and a second rotor 1004. The first rotor 1002 and the second rotor 1004 are configured to rotate about an axis of rotation 1006. The axial flux motor 1000 also includes a stator 1008. The stator 1008 is positioned between the first rotor 1002 and the second rotor 1004, and a first airgap 1010 and a second airgap 1012 are formed on either side of the stator 1008. The stator 1008 includes a plurality of stator windings 1014 that are circumferentially wound around the stator 1008. In some embodiments, the stator 1008 is a coreless stator. In place of the stator core, a printed circuit board or an epoxy is used to hold the stator windings in place. The first rotor 1002 and the second rotor 1004 each include a plurality of permanent magnets 1016. The plurality of permanent magnets 1016 form a plurality of permanent magnet poles on the first rotor 1002 and the second rotor 1004. The first rotor 1002 and the second rotor 1004 are configured to rotate with respect to the stator 1008 and about the axis of rotation 1006. The stator windings 1014 are configured to be selectively energized to cause rotation of the first rotor 1002 and the second rotor 1004 about the axis or rotation 1006. The axial flux motor 1000 is configured to allow magnetic flux to travel along a magnetic flux path 1018. The magnetic flux crosses the first airgap 1010 and the second airgap 1012 in a direction parallel to an axis of rotation 1006 of the axial flux motor 1000. The flux path 1018 intersects the plurality of permanent magnets 1016 positioned on the first rotor 1002 and the second rotor 1004. The double airgap double rotor coreless axial flux motor 1000 provides for the lowest cogging torque of any of the axial flux motor designs, but produces low torque density.

[0045] FIG. 11 illustrates an axial flux motor 1100 for use with the power tool 100. The axial flux motor 1100 includes a first stator 1102 and a second stator 1104. In some implementations, the first stator 1102 and the second stator 1104 are slotted core stators. The first stator 1102 and the second stator 1104 each include a plurality of stator windings 1106 that are circumferentially wound around the stator. In some embodiments, the first stator 1102 and the second stator 1104 are made of steel laminations. In other embodiments, the first stator 1102 and the second stator 1104 are made of an SMC material. The axial flux motor 1100 alsoAttorney Docket No. 066042- 1891 -WOO 1 includes a rotor 1108. The rotor 1108 is positioned between the first stator 1 102 and the second stator 1104, and an airgap 1110 is formed on either side of the rotor 1108. In some embodiments, the airgap 1110 is considered to be a dual airgap because of two layers of magnets 1112 being present. The rotor 1108 includes a plurality of permanent magnets 1112. The plurality of permanent magnets 1112 form a plurality of permanent magnet poles on the rotor 1108. The rotor 1108 is configured to rotate with respect to the first stator 1102 and the second stator 1104 and about an axis of rotation 1114. The stator windings 1106 are configured to be selectively energized to cause rotation of the rotor 1108 about the axis or rotation 1114. The axial flux motor 1100 is configured to allow magnetic flux to travel along a magnetic flux path 1116. The magnetic flux crosses the airgap 1110 in a direction parallel to the axis of rotation 1114 of the axial flux motor 1100. The flux path 1116 intersects the plurality of permanent magnets 1112 positioned on the rotor 1108. The dual stator axial flux motor 1100 provides for reduced motor inertia among axial flux motor designs. The axial flux motor 1100 also produces more torque than a single airgap axial flux motor, and has the lowest stator-rotor force of attraction among the axial flux motor designs.

[0046] FIG. 12 illustrates an axial flux motor 1200 for use with the power tool 100. The axial flux motor 1200 is configured as a multi-stage axial flux motor. The axial flux motor 1200 includes a first rotor 1202, a second rotor 1204, and a third rotor 1206. The first rotor 1202, the second rotor 1204, and the third rotor 1206 are configured to rotate about an axis of rotation 1208. The axial flux motor 1200 also includes a first stator 1210 (e.g., a slotted stator core) and a second stator 1212 (e g., a slotted stator core). The first stator 1210 is positioned between the first rotor 1202 and the third rotor 1206, and a first airgap 1214 is formed on an upper side of the first stator 1210. The second stator 1212 is positioned between the second rotor 1204 and the third rotor 1206, and a second airgap 1216 is formed on a lower side of the second stator 1210. A third airgap 1218 is formed between the first stator 1210 and the second stator 1212. The stators 1210, 1212 each include a plurality of stator windings 1220 that are circumferentially wound around the slotted stator core. In some embodiments, the stators 1210, 1212 are made of steel laminations. In other embodiments, the stators 1210, 1212 are made of an SMC material. The first rotor 1202, the second rotor 1204, and the third rotor 1206 each include a plurality of permanent magnets 1222. The plurality of permanent magnets 1222 form a plurality of permanent magnet poles on the first rotor 1202, the second rotor 1204, and the third rotor 1206.Attorney Docket No. 066042- 1891 -WOO 1The first rotor 1202, the second rotor 1204, and the third rotor 1206 are configured to rotate with respect to the stators 1210, 1212 and about the axis of rotation 1208. The stator windings 1220 are configured to be selectively energized to cause rotation of the first rotor 1202, second rotor 1204, and third rotor 1206 about the axis or rotation 1206. The axial flux motor 1200 is configured to allow magnetic flux to travel along a magnetic flux path 1224. The magnetic flux crosses the first airgap 1214, the second airgap 1216, and the third airgap 1218 in a direction parallel to an axis of rotation 1208 of the axial flux motor 1200. The flux path 1224 intersects the plurality of permanent magnets 1222 positioned on the first rotor 1202, the second rotor 1204, and the third rotor 1206.

[0047] FIG. 13 illustrates an axial flux motor 1300 for use with the power tool 100. The axial flux motor 1300 is configured as a multi-stage coreless axial flux motor. The axial flux motor 1300 includes a first rotor 1302, a second rotor 1304, and a third rotor 1306. The first rotor 1302, the second rotor 1304, and the third rotor 1306 are configured to rotate about an axis of rotation 1308. The axial flux motor 1300 also includes a first stator 1310 and a second stator 1312. The first stator 1310 is positioned between the first rotor 1302 and the third rotor 1306, and a first airgap 1314 is formed on an upper side of the first stator 1310 and a second airgap 1316 is formed on a lower side of the first stator 1310. The second stator 1312 is positioned between the second rotor 1304 and the third rotor 1306, and a third airgap 1318 is formed on an lower side of the second stator 1312 and a fourth airgap 1320 is formed on an upper side of the second stator 1312. The stators 1310, 1312 each include a plurality of stator windings 1322 that are circumferentially wound around the stator. In some embodiments, the first stator 1310 and the second stator 1312 are coreless stators. In place of the stator core, a printed circuit board or an epoxy is used to hold the stator windings in place. The first rotor 1302, the second rotor 1304, and the third rotor 1306 each include a plurality of permanent magnets 1324. The plurality of permanent magnets 1324 form a plurality of permanent magnet poles on the first rotor 1302, the second rotor 1304, and the third rotor 1306. The third rotor 1306 incudes sets of magnets 1324 on both the upper and lower surfaces of the third rotor 1306. The first rotor 1302, the second rotor 1304, and the third rotor 1306 are configured to rotate with respect to the stators 1310, 1312 and about the axis of rotation 1308. The stator windings 1322 are configured to be selectively energized to cause rotation of the first rotor 1302, second rotor 1304, and third rotor 1306 about the axis or rotation 1308. The axial flux motor 1300 is configured to allow magneticAttorney Docket No. 066042- 1891 -WOO 1 flux to travel along a magnetic flux path 1326. The magnetic flux crosses the first airgap 1314, the second airgap 1316, the third airgap 1318, and the fourth airgap 1320 in a direction parallel to an axis of rotation 1308 of the axial flux motor 1300. The flux path 1326 intersects the plurality of permanent magnets 1324 positioned on the first rotor 1302, the second rotor 1304, and the third rotor 1306.REPRESENTATIVE FEATURES

[0048] Representative features are set out in the following clauses, which stand alone or may be combined, in any combination, with one or more features disclosed in the text and / or drawings of the specification.

[0049] Clause 1. A power tool comprising: a battery pack interface configured to receive a battery pack; and an axial flux motor including: a stator including: a stator core made of soft magnetic composite material, and a plurality of winding coils, and a rotor configured to rotate with respect to the stator, the rotor including: a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles, wherein a magnetic flux path crosses between the stator and the rotor in a direction parallel to an axis of rotation of the rotor.

[0050] Clause 2. The power tool of clause 1, wherein the stator and the rotor are separated by an airgap.

[0051] Clause 3. The power tool of clause 2, wherein the magnetic flux path crosses the airgap between the stator and the rotor.

[0052] Clause 4. The power tool of clause 1, further comprising; a second stator configured to be separated from the stator by the rotor and the plurality of permanent magnets.

[0053] Clause 5. The power tool of clause 1, further comprising; a second rotor separated from the rotor by the stator.

[0054] Clause 6. The power tool of clause 1, wherein the plurality of winding coils is oriented radially.

[0055] Clause 7. The power tool of clause 1, wherein the plurality of winding coils is oriented circumferentially.Attorney Docket No. 066042- 1891 -WOO 1

[0056] Clause 8. The power tool of clause 1, wherein: the axial flux motor has a diameter and a length; and the length is less than the diameter.

[0057] Clause 9. The power tool of clause 8, wherein the length of the axial flux motor is less than 0.4D, wherein D is the diameter of the axial flux motor.

[0058] Clause 10. The power tool of clause 8, wherein the diameter of the axial flux motor is between 25 mm and 150 mm.

[0059] Clause 11. The power tool of clause 10, wherein the length of the axial flux motor is less than 60 mm.

[0060] Clause 12. A power tool comprising: a battery pack interface configured to receive a battery pack; and an axial flux motor including: a first stator including: a stator core made of soft magnetic composite material, and a plurality of winding coils, and a first rotor and a second rotor configured to rotate with respect to the first stator, the first rotor and the second rotor each including: a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles, wherein a magnetic flux path crosses between the first rotor, the first stator, and the second rotor in a direction parallel to an axis of rotation of the first rotor.

[0061] Clause 13. The power tool of clause 12, further comprising: a first airgap and a second airgap formed on either side of the first stator.

[0062] Clause 14. The power tool of clause 12, wherein: the axial flux motor has a diameter and a length; and the length is less than the diameter.

[0063] Clause 15. The power tool of clause 14, wherein the length of the axial flux motor is less than 0.6D, wherein D is the diameter of the axial flux motor.

[0064] Clause 16. The power tool of clause 14, wherein the diameter of the axial flux motor is between 25 mm and 150 mm.

[0065] Clause 17. The power tool of clause 16, wherein the length of the axial flux motor is less than 90 mm.

[0066] Clause 18. The power tool of clause 12, wherein the stator core is a slotted stator core.Attorney Docket No. 066042- 1891 -WOO 1

[0067] Clause 19. The power tool of clause 12, wherein the axial flux motor is a multi-stage axial flux motor further comprising: a third rotor, wherein the first stator is positioned between the first rotor and the second rotor; and a second stator, wherein the second stator is positioned between the first rotor and the third rotor.

[0068] Clause 20. A power tool comprising: a battery pack interface configured to receive a battery pack; and an axial flux motor including: a first stator and a second stator each including: a plurality of winding coils, and a first rotor configured to rotate with respect to the first stator, the first rotor and including: a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles, wherein a magnetic flux path crosses between the first stator, the first rotor, and the second stator in a direction parallel to an axis of rotation of the first rotor.

[0069] Clause 21. The power tool of clause 20, wherein the first stator and the second stator further include: a stator core made of soft magnetic composite material.

[0070] Clause 22. The power tool of clause 20, wherein the first stator and the second stator further include: a stator core made of solid steel or steel laminations.

[0071] Clause 23. The power tool of clause 20, wherein at least one of the first stator and the second stator is a coreless stator.

[0072] Clause 24. The power tool of clause 23, wherein a printed circuit board or an epoxy holds the plurality of winding coils in place.

[0073] Clause 25. The power tool of clause 20, wherein the axial flux motor is a multi-stage axial flux motor further comprising: a second rotor, wherein the first stator is positioned between the first rotor and the second rotor; and a third rotor, wherein the second stator is positioned between the first rotor and the third rotor.

[0074] Clause 26. The power tool of clause 25, the multi-stage axial flux motor further comprising: a first airgap formed on an upper side of the first stator; a second airgap formed on a lower side of the second stator; and a third airgap formed between the first stator and the second stator.

[0075] Clause 27. The power tool of clause 25, the multi-stage axial flux motor further comprising: a first airgap formed on an upper side of the first stator; a second airgap formed on aAttorney Docket No. 066042- 1891 -WOO 1 lower side of the first stator; a third airgap formed on a lower side of the second stator; and a fourth airgap formed on an upper side of the second stator.

[0076] Thus, embodiments described herein provide, among other things, power tools including axial flux motors. Various features and advantages are set forth in the following claims.

Claims

Attorney Docket No. 066042- 1891 -WOO 1CLAIMSWe claim:

1. A power tool comprising: a battery pack interface configured to receive a battery pack; and an axial flux motor including: a stator including: a stator core made of soft magnetic composite material, and a plurality of winding coils, and a rotor configured to rotate with respect to the stator, the rotor including: a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles, wherein a magnetic flux path crosses between the stator and the rotor in a direction parallel to an axis of rotation of the rotor.

2. The power tool of claim 1, wherein the stator and the rotor are separated by an airgap.

3. The power tool of claim 2, wherein the magnetic flux path crosses the airgap between the stator and the rotor.

4. The power tool of claim 1, further comprising; a second stator configured to be separated from the stator by the rotor and the plurality of permanent magnets.

5. The power tool of claim 1, further comprising; a second rotor separated from the rotor by the stator.

6. The power tool of claim 1, wherein the plurality of winding coils is oriented radially.

7. The power tool of claim 1, wherein the plurality of winding coils is oriented circumferentially.Attorney Docket No. 066042- 1891 -WOO 18. The power tool of claim 1, wherein: the axial flux motor has a diameter and a length; and the length is less than the diameter.

9. The power tool of claim 8, wherein the length of the axial flux motor is less than 0.4D, wherein D is the diameter of the axial flux motor.

10. The power tool of claim 8, wherein the diameter of the axial flux motor is between 25 mm and 150 mm.

11. The power tool of claim 10, wherein the length of the axial flux motor is less than 60 mm.

12. A power tool compri sing : a battery pack interface configured to receive a battery pack; and an axial flux motor including: a first stator including: a stator core made of soft magnetic composite material, and a plurality of winding coils, and a first rotor and a second rotor configured to rotate with respect to the first stator, the first rotor and the second rotor each including: a rotor core, and a plurality of permanent magnets forming a plurality of permanent magnet poles, wherein a magnetic flux path crosses between the first rotor, the first stator, and the second rotor in a direction parallel to an axis of rotation of the first rotor.

13. The power tool of claim 12, further comprising: a first airgap and a second airgap formed on either side of the first stator.Attorney Docket No. 066042- 1891 -WOO 114. The power tool of claim 12, wherein: the axial flux motor has a diameter and a length; and the length is less than the diameter.

15. The power tool of claim 14, wherein the length of the axial flux motor is less than 0.6D, wherein D is the diameter of the axial flux motor.

16. The power tool of claim 14, wherein the diameter of the axial flux motor is between 25 mm and 150 mm.

17. The power tool of claim 16, wherein the length of the axial flux motor is less than 90 mm.

18. The power tool of claim 12, wherein the stator core is a slotted stator core.

19. The power tool of claim 12, wherein the axial flux motor is a multi-stage axial flux motor further comprising: a third rotor, wherein the first stator is positioned between the first rotor and the second rotor; and a second stator, wherein the second stator is positioned between the first rotor and the third rotor.

20. A power tool comprising: a battery pack interface configured to receive a battery pack; and an axial flux motor including: a first stator and a second stator each including: a plurality of winding coils, and a first rotor configured to rotate with respect to the first stator, the first rotor including: a rotor core, andAttorney Docket No. 066042- 1891 -WOO 1 a plurality of permanent magnets forming a plurality of permanent magnet poles, wherein a magnetic flux path crosses between the first stator, the first rotor, and the second stator in a direction parallel to an axis of rotation of the first rotor.

21. The power tool of claim 20, wherein the first stator and the second stator further include: a stator core made of soft magnetic composite material.

22. The power tool of claim 20, wherein the first stator and the second stator further include: a stator core made of solid steel or steel laminations.

23. The power tool of claim 20, wherein at least one of the first stator and the second stator is a coreless stator.

24. The power tool of claim 23, wherein a printed circuit board holds the plurality of winding coils in place.

25. The power tool of claim 20, wherein the axial flux motor is a multi-stage axial flux motor further comprising: a second rotor, wherein the first stator is positioned between the first rotor and the second rotor; and a third rotor, wherein the second stator is positioned between the first rotor and the third rotor.

26. The power tool of claim 25, the multi-stage axial flux motor further comprising: a first airgap formed on an upper side of the first stator; a second airgap formed on a lower side of the first stator; a third airgap formed on an upper side of the second stator; and a fourth airgap formed on a lower side of the second stator.

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