Electric tool

Abstract

The power tool may include a battery pack interface configured to receive a removable and rechargeable battery pack. In one embodiment, an apparatus may include an outer rotor electric machine including a stator including a plurality of stator teeth configured to receive a plurality of stator coils and a rotor configured to rotate about the stator. The rotor includes a first permanent magnet disposed on an inner surface of the rotor, a second permanent magnet disposed on the inner surface of the rotor, and an air slot on the inner surface of the rotor between the first permanent magnet and the second permanent magnet. The air slot has a length and a width. The length of the air groove is larger than that of the first permanent magnet or the second permanent magnet.

Description

[0001] Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 386,699 filed on December 9, 2022 and U.S. Provisional Patent Application No. 63 / 497,485 filed on April 21, 2023, all of which are incorporated by reference into this application. Technical Field

[0003] The specific embodiments described in this application relate to a motor for a power tool. Background Art

[0004] Traditional outer rotor motors have defects such as poor durability, imprecise speed regulation, and non-compact structure. For example, the steel loss of traditional outer rotor motors increases significantly with the increase of output power and motor speed. The present application provides a motor with better performance and more compact structure, and at the same time, relevant improvements are made in terms of manufacturing cost and the use of magnetic materials. Utility Model Content

[0005] The power tool described in the present application includes a battery pack interface, which is configured to receive a removable and rechargeable battery pack and an outer rotor motor. The outer rotor motor includes a stator and a rotor configured to rotate around the stator, and the stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first permanent magnet disposed on the inner surface of the rotor, a second permanent magnet disposed on the inner surface of the rotor, and an air slot located between the first permanent magnet and the second permanent magnet on the inner surface of the rotor. The air slot has a length and a width. The length of the air slot is greater than the length of the first permanent magnet or the second permanent magnet.

[0006] In some aspects, the stator includes at least twelve stator slots and the rotor includes at least five rotor poles.

[0007] In some aspects, the first permanent magnet and the second permanent magnet are composed of a rare earth metal.

[0008] In some aspects, the rotor further includes consecutive poles disposed in the air slots.

[0009] In some aspects, the alternating poles are iron poles.

[0010] In some aspects, the alternating poles comprise a length of about 1 mm to 12 mm.

[0011] In some aspects, the alternating poles are iron poles.

[0012] In some aspects, the alternating poles comprise a length of about 1 mm to 12 mm.

[0013] In some aspects, the rotor further includes a lamination stack including an inner lamination portion and an outer lamination portion and a plastic mold, wherein the plastic mold is configured to increase retention of the lamination stack.

[0014] In some aspects, the inner lamination portion includes a triangular groove portion configured to retain the first portion of the plastic mold to secure the plastic mold to the inner lamination portion.

[0015] In some aspects, the outer lamination portion includes an L-shaped portion configured to retain the second portion of the plastic mold to secure the outer lamination portion to the plastic mold.

[0016] In some aspects, the plastic mold is made of a non-magnetic material.

[0017] The power tool described in the present application includes a battery pack interface, which is configured to receive a removable and rechargeable battery pack and a motor. The motor includes a stator and a rotor configured to rotate within the stator, and the stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first permanent magnet disposed in a first slot of the rotor, a second permanent magnet disposed in a second slot of the rotor, a first alternating pole disposed between the first permanent magnet and the second permanent magnet, and a second alternating pole disposed between the first permanent magnet and the second permanent magnet, wherein the first alternating pole has a first length and a first width, and the second alternating pole has a second length and a second width.

[0018] In some aspects, the rotor comprises an outer diameter of approximately 22 mm.

[0019] In some aspects, the first permanent magnet and the second permanent magnet are composed of a rare earth metal.

[0020] In some aspects, the first permanent magnet comprises a length of about 1 mm to 12 mm and a width of about 2 mm to 3 mm.

[0021] In some aspects, the rotor further includes a lamination stack and an air slot.

[0022] In some aspects, the air slots are located within the lamination stack and extend along the rotor in a transverse direction relative to the axial direction.

[0023] In some aspects, the air slot includes a length extending approximately 45-degrees away from the first permanent magnet in a direction toward the first alternating pole.

[0024] The power tool described in the present application includes a battery pack interface, which is configured to receive a removable and rechargeable battery pack and a motor. The motor includes a stator and a rotor, and the stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor is configured to rotate within the stator. The rotor includes a lamination stack, a first air slot located in the lamination stack and extending along the rotor in a transverse direction relative to the axial direction, a second air slot located in the lamination stack and extending along the rotor in a transverse direction relative to the axial direction, a first permanent magnet disposed in the first slot of the rotor, a second permanent magnet disposed in the second slot of the rotor, a first alternating pole disposed between the first permanent magnet and the second permanent magnet, and a second alternating pole disposed between the first permanent magnet and the second permanent magnet, wherein the first alternating pole has a first length and a first width, and the second alternating pole has a second length and a second width.

[0025] In some aspects, the first air slot includes a first air slot length extending approximately 45 degrees away from the first permanent magnet in a direction toward the first alternating pole, and the second air slot includes a second air slot length extending approximately 45 degrees away from the second permanent magnet in a direction toward the second alternating pole.

[0026] In some aspects, the first air slot length is designed based on the length of the first permanent magnet, and the second air slot length is designed based on the length of the second permanent magnet.

[0027] The power tool described in the present application includes a battery pack interface, which is configured to receive a removable and rechargeable battery pack and a consequent pole motor. The consequent pole motor includes a stator and a rotor configured to rotate around the stator, and the stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first permanent magnet disposed on the inner surface of the rotor, a second permanent magnet disposed on the inner surface of the rotor, and an alternating pole located between the first permanent magnet and the second permanent magnet on the inner surface of the rotor. The alternating pole has a length and a width. The alternating pole is made of a non-magnetic material.

[0028] The power tool described in the present application includes a battery pack interface, which is configured to receive a removable and rechargeable battery pack and an alternating pole motor. The alternating pole motor includes a stator and a rotor configured to rotate within the stator, and the stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first permanent magnet disposed in a first groove of the rotor, a second permanent magnet disposed in a second groove of the rotor, a first alternating pole disposed between the first permanent magnet and the second permanent magnet, and a second alternating pole disposed between the first permanent magnet and the second permanent magnet. The first alternating pole has a first length and a first width, and the second alternating pole has a second length and a second width.

[0029] Before any specific embodiment is described in detail, it should be understood that the specific embodiments in this application are not limited to the details of the configuration and arrangement of the components described in the following description or shown in the accompanying drawings. The specific embodiments can be implemented or realized in various ways. In addition, it should be understood that the words and terms used in this application are for illustrative purposes and not for limitation. The use of "including", "comprising", "having" and their variations means that both the items listed thereafter and their equivalents and additional items are covered. Unless otherwise specified or limited, the terms "install", "connect", "support", "couple" and their variations are used in a broad sense, covering both direct installation, connection, support and coupling, and indirect installation, connection, support and coupling.

[0030] The articles "a," "an," and "the" should not be construed as meaning "one" or "only one," unless the context clearly indicates otherwise. Instead, these articles should be construed as meaning "at least one" or "one or more." Similarly, when the terms "the" or "said" are used to refer to a noun previously introduced by the indefinite article "a" or "an," "the" or "said" means "at least one" or "one or more," unless the context clearly indicates otherwise.

[0031] In addition, it should be understood that specific embodiments may include hardware, software, and electronic components or modules, and for the purpose of discussion, these hardware, software, and electronic components or modules will be shown and described as most of the components are implemented only in hardware. However, based on the reading of the specific embodiments of the present application, those skilled in the art will recognize that in at least one specific embodiment, the electronic-based aspects can be implemented in software (e.g., stored on a non-transient computer-readable medium), and the software can be executed by one or more processing units such as microprocessors and / or application-specific integrated circuits (ASICs). Therefore, it should be noted that these specific embodiments can be implemented using a plurality of hardware- and software-based devices and a plurality of different structural components. For example, the "server", "computing device", "controller" and "processor" in this specification may include one or more processing units, one or more computer-readable medium modules, one or more input / output interfaces, and various connectors (e.g., system buses) connecting these components.

[0032] Relative terms such as "about", "approximately", "substantially", etc., used in relation to quantities or conditions, will be understood by those skilled in the art to include the values, and the meaning of the terms is determined by the context (e.g., the terms include at least the degree of error associated with the precision of the measurements, the tolerance associated with the specific values ​​[e.g., manufacturing, assembly, use, etc.], etc.). Such terms should also be considered to disclose 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 of "from 2 to 4". Relative terms may refer to positive and negative percentages (e.g., 1%, 5%, 10%) of the indicated value.

[0033] It should be understood that although some drawings show hardware and software located in a particular device, these depictions are for illustrative purposes only. The functions performed by a component described in this application can be performed by multiple components in a distributed manner. Similarly, the functions performed by multiple components can be merged and performed by a single component. In some specific embodiments, the components shown can be combined or divided into separate software, firmware and / or hardware. For example, logical operations and processing can be distributed between multiple electronic processors, rather than being in a single electronic processor and performed by a single electronic processor. Regardless of how they are combined or divided, hardware components and software components can be located in the same computing device, or can be distributed between different computing devices connected by one or more networks or other suitable communication links. Similarly, components described as performing specific functions can also perform additional functions not described in this application. For example, a device or structure that is "configured" in a certain way is configured at least in this way, but can also be configured in a way that is not explicitly listed.

[0034] Accordingly, in a claim, if an apparatus, method, or system is stated as, for example, including a controller, a control unit, an electronic processor, a computing device, a logic element, a memory module, a communication channel or network, or other element that is configured in some manner (e.g., configured to perform multiple functions), such claim or element of the claim should be interpreted to mean one or more of such elements, in which any one of the one or more elements is configured as described in the claim, for example, to perform any one or more of the listed multiple functions, so that the one or more elements as a whole collectively perform the multiple functions.

[0035] Other aspects of the embodiments will become apparent by consideration of the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A perspective view of a power tool according to some specific embodiments is shown.

[0037] Figure 2 According to some specific embodiments, Figure 1 Block diagram of the control system of a power tool.

[0038] Figure 3 According to some specific embodiments, Figure 1 Battery packs used in power tools.

[0039] Figure 4 According to some specific embodiments, Figure 3 Block diagram of the battery pack's control system.

[0040] Figure 5A An outer rotor electric machine is shown according to some specific embodiments.

[0041] Figure 5B An outer rotor electric machine is shown according to some specific embodiments.

[0042] Figure 5C An outer rotor electric machine is shown according to some specific embodiments.

[0043] Figure 5D An outer rotor electric machine is shown according to some specific embodiments.

[0044] Figure 6 The relationship between steel loss and output power according to some specific embodiments is shown in graphical form.

[0045] Figure 7 The relationship between steel loss and speed is shown in graphical form according to some embodiments.

[0046] Figure 8 Magnetic flux flow in an outer rotor electric machine and an alternating pole electric machine is shown according to some specific embodiments.

[0047] Fig. 9 The performance of various electric machines according to some specific embodiments is shown in graphical form.

[0048] Fig.10 An inner rotor electric machine is shown according to some specific embodiments.

[0049] Fig.11 According to some specific embodiments, Fig.10 Exploded view of an inner rotor motor.

[0050] Fig.12 An inner rotor motor is shown in an airflow test fixture, according to some embodiments.

[0051] Fig.13 An alternating pole electric machine rotor is shown according to some specific embodiments.

[0052] Fig.14An alternating pole electric machine rotor is shown according to some specific embodiments.

[0053] Fig.15A An interior permanent magnet motor is shown according to some specific embodiments.

[0054] Fig. 15B An interior permanent magnet motor is shown according to some specific embodiments.

[0055] Fig. 15C An alternating-pole electric machine is shown according to some specific embodiments.

[0056] Fig.16 Magnetic flux flow in an alternating pole machine and an interior permanent magnet machine is shown according to some specific embodiments.

[0057] Fig.17 The performance of an alternating pole motor and an interior permanent magnet motor according to some specific embodiments is shown in graphical form.

[0058] Fig.18 The relationship between steel loss and speed for an alternating-pole electric machine according to some embodiments is shown in graphical form.

[0059] Fig.19 The relationship between steel loss and output power of an alternating-pole machine according to some embodiments is shown in graphical form.

[0060] Fig. 20A An alternating-pole electric machine is shown according to some specific embodiments.

[0061] Fig. 20B An alternating-pole electric machine according to some specific embodiments is shown.

[0062] Fig.21 The performance of various alternating-pole electric machines according to some specific embodiments is shown in graphical form.

[0063] Fig. 22 The torque ripple of an alternating-pole electric machine according to some specific embodiments is illustrated in graphical form.

[0064] Fig.23 An interior permanent magnet motor rotor is shown according to some specific embodiments.

[0065] Fig.24A An interior permanent magnet motor is shown according to some specific embodiments.

[0066] Fig. 24B An interior permanent magnet motor is shown according to some specific embodiments.

[0067] Fig.24CAn interior permanent magnet motor is shown according to some specific embodiments.

[0068] Fig.25 An electric machine according to some specific embodiments is shown.

[0069] Fig.26 The performance of different electric machines according to some specific embodiments is shown in graphical form.

[0070] Fig. 27 An alternating-pole electric machine is shown according to some specific embodiments.

[0071] Fig.28 The performance of different electric machines according to some specific embodiments is shown in graphical form.

[0072] Fig.29 An interior permanent magnet motor is shown according to some specific embodiments.

[0073] Fig.30 The performance of various electric machines according to some specific embodiments is shown in graphical form. DETAILED DESCRIPTION

[0074] Figure 1 A power tool 100 including a permanent magnet motor is shown. For example, the power tool 100 is a hammer drill including a housing 102. The housing 102 includes a handle portion 104 and a motor housing portion 106. The power tool 100 further includes an output driver 108 (shown 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 a power tool battery pack or to receive a power tool battery pack (also referred to as a removable and / or rechargeable battery pack). Although Figure 1 An impact drill is shown, but in some embodiments, the components described in this application are incorporated into other types of power tools, including electric drills, impact drills, impact wrenches, angle grinders, circular saws, reciprocating saws, plate compactors, core drills, lawn mowers, leaf blowers, vacuum cleaners, etc. In a permanent magnet motor power tool such as the power tool 100, the switching element is selectively opened and closed by a control signal from a controller to selectively apply power from a power source (e.g., a battery pack) to drive the permanent magnet motor.

[0075] Figure 2A control system 200 for a power tool 100 is shown. The control system 200 includes a controller 202. The controller 202 is electrically and / or communicatively connected to various modules or components of the power tool 100. For example, the controller 202 is shown to be electrically connected to a motor 204, a battery pack interface 206, a trigger switch 208 (connected to a trigger 210), one or more sensors 212 or sensing circuits, one or more indicators 214, a user input module 216, a power input module 218, an inverter bridge or FET switch module 220 (e.g., including a plurality of switching FETs), and a gate driver 224 for driving the FET switch module 220. In some specific embodiments, the motor 204 is a permanent magnet motor. The controller 202 includes a combination of hardware and software that can be operated to (among other things) control the operation of the power tool 100, monitor the operation of the power tool 100, and activate one or more indicators 214 (e.g., LEDs), etc.

[0076] The controller 202 includes a plurality of electrical and electronic components for providing power, operational control, and protection for the components or 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, an input unit 230, and an output unit 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 and a von Neumann architecture, etc.). The processing unit 226, the memory 228, the input unit 230, and the output unit 232, as well as the various modules or circuits connected to the controller 202, are connected via one or more control buses and / or data buses (e.g., a common bus 240). For illustrative purposes, Figure 2 The control bus and / or data bus are generally shown in FIG. For the invention described in this application, it is well known to those skilled in the art to use one or more control buses and / or data buses for interconnection and communication between various modules, circuits and components.

[0077] 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 may include a combination of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card, or other applicable magnetic, optical, physical or electronic storage devices. The processing unit 226 is connected to the memory 228 and executes software instructions, which may be stored in the RAM of the memory 228 (e.g., during execution), the ROM of the memory 228 (e.g., on a generally permanent basis), or other non-transitory computer-readable media such as another memory or an optical disk. The software included in implementing the power tool 100 may be stored in the memory 228 of the controller 202. The software includes, for example, firmware, one or more application programs, program data, filters, rules, one or more program modules, and other executable instructions. The controller 202 is configured to retrieve and execute instructions related to the control process and method described in the present application from the memory 228, among others. In other configurations, the controller 202 includes additional components, fewer components, or different components.

[0078] The battery pack interface 206 includes a combination of mechanical components (e.g., tracks, slots, latches, etc.) and electrical components (e.g., one or more terminals) that are configured and operable to interface (e.g., mechanically, electrically, and communicatively connect) with the battery pack. For example, the battery pack 300 (see Figure 3 ) The power provided to the power tool 100 is provided to the power input module 218 through the battery pack interface 206. The power input module 218 includes a combination of active and passive components to regulate or control the power received from the battery pack 300 before the power is provided to the controller 202. The battery pack interface 206 also supplies power to the FET switch module 220 to selectively provide power to the motor 204 by switching the switching FET. 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.

[0079] The sensor 212 includes one or more current sensors, one or more speed sensors, one or more Hall effect sensors, one or more temperature sensors, etc. The indicator 214 includes, for example, one or more light emitting diodes (LEDs). The indicator 214 can be configured to display the status of the power tool 100 or information associated with the power tool 100. For example, the indicator 214 is configured to indicate the measured electrical characteristics of the power tool 100, the status of the power tool, and the status of the motor 204, etc. The user input module 216 is operably coupled to the controller 202, for example, to select a forward operating mode or a reverse operating mode and a torque and / or speed setting for the power tool 100 (for example, using a torque and / or speed switch), etc. In some specific embodiments, the user input module 216 includes a combination of digital and analog input or output devices required to achieve the desired operating level of the power tool 100, such as one or more knobs, one or more dials, one or more switches, and one or more buttons, etc.

[0080] Figure 3 A battery pack 300 is shown. 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.

[0081] Figure 4 A control system for a battery pack 300 is shown. The control system includes a controller 400. The controller 400 is electrically and / or communicatively connected to various modules or components of the battery pack 300. For example, the controller 400 is shown connected to one or more battery cells 402 and an interface 404 (e.g., Figure 3 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. Controller 400 includes a combination of hardware and software that can be operated to (among other things) control the operation of battery pack 300, monitor the condition of battery pack 300, turn charging of battery pack 300 on or off, turn discharging of battery pack 300 on or off, etc.

[0082] The controller 400 includes a plurality of electrical and electronic components that provide power, operational control, and protection for 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, an input unit 416, and an output unit 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 and a von Neumann architecture, etc.). The processing unit 412, the memory 414, the input unit 416, and the output unit 418, as well as the various modules or circuits connected to the controller 400, are connected via one or more control buses and / or data buses (e.g., a common bus 426). For illustrative purposes, Figure 4 The control bus and / or data bus are generally shown in FIG. For the invention described in this application, it is well known to those skilled in the art to use one or more control buses and / or data buses for interconnection and communication between various modules, circuits and components.

[0083] 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 may include a combination of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card, or other applicable magnetic, optical, physical or electronic storage devices. The processing unit 412 is connected to the memory 414 and executes software instructions, which may be stored in the RAM of the memory 414 (e.g., during execution), the ROM of the memory 414 (e.g., on a generally permanent basis), or other non-transitory computer-readable media such as another memory or an optical disk. The software included in implementing the power tool 300 may be stored in the memory 414 of the controller 400. The software includes, for example, firmware, one or more application programs, program data, filters, rules, one or more program modules, and other executable instructions. The controller 400 is configured to retrieve and execute instructions related to the control process and method described in the present application from the memory 414, among others. In other configurations, the controller 400 includes additional components, fewer components, or different components.

[0084] The interface 404 includes a combination of mechanical components (e.g., tracks, slots, latches, etc.) and electrical components (e.g., one or more terminals) that are configured and operable to interface (e.g., mechanically, electrically, and communicatively connect) 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 be communicatively connected to the controller 400 via a communication line 428.

[0085] Figures 5A to 5B An outer rotor motor according to various specific embodiments is shown. Figure 5A As shown, the motor 500A includes an internal stator 505 and a plurality of stator winding slots 510. The stator also includes a stator tooth portion 513. The plurality of stator winding slots 510 are configured to receive a plurality of windings (also referred to as stator coils) wound around the stator tooth portion 513. The motor 500A also includes an outer rotor 515. The rotor 515 is configured to rotate around the internal stator 505. The rotor 505 includes a plurality of permanent magnets 520 (e.g., magnets composed of rare earth metals) along the inside of the rotor 515 (e.g., along the inner surface) and facing the internal stator 505. In the specific embodiment shown, the rotor includes a total of ten magnets. The outer rotor 515 includes an air slot 525. The air slot 525 has a width 530 and a length 535. The magnet 520 of the rotor 515 is configured to have a north pole 540 and a south pole 545. Figure 5B 5 is a motor 500B in a five magnet outer rotor configuration. In this configuration, the number of magnets 520 can be reduced to reduce the manufacturing cost of the motor 500B and reduce the environmental impact caused by the use of rare earth magnetic materials. In this configuration, the air slot length 535 is larger between the magnets 520, so that the air slot 525 corresponds to the permanent magnets 520 that have been removed from the rotor. Thus, the air slot length 535 is greater than the length of the magnets 520 along the interior of the rotor 515.

[0086] Figure 5C Shown in FIG. 5 is a motor 500C having an optimized alternating pole motor configuration. One of the features of the alternating pole motors described herein (e.g., motor 500C) is the ability to provide variable speed control. For example, by adjusting the current through a plurality of stator windings, motor 500C can be operated at different speeds. This is particularly advantageous in power tool applications where precise speed control is important. In addition, the alternating pole motors described herein (e.g., motor 500C) are more durable, have finer speed regulation, and are generally more compact than conventional motors. Some additional advantages such as Figure 6 and 7, and described in more detail below. In some embodiments, the alternating poles may be iron poles 550. In some embodiments, the alternating poles may be constructed from several rotor laminations.

[0087] Reference Figure 5D , which further shows a motor 500C including an iron pole 550. The iron pole 550 has a width 555 and a length 560. In some embodiments, the length 560 or the width 555 of the iron pole 550 is used to control the performance of the motor 500C. For example, a 5mm iron pole length may have an effect on torque ripple, cogging torque, etc. In some embodiments, the iron pole 550 has a length 560 of 1mm to 12mm. For example, the length 560 of the iron pole 550 may be advantageously designed to be 10mm. In some embodiments, a longer length 560 of the iron pole 550 may provide lower torque ripple than a narrower length 560 of the iron pole 550. Other measurements may also change the performance of the motor 500C. The outer rotor alternating pole motor can be optimized by manipulating the size of the iron pole 550.

[0088] Figure 6 The relationship between steel losses and output power of a conventional outer rotor motor (e.g., motors 500A, 500B) and an alternating pole motor is shown in graphical form. In some embodiments, the alternating pole motor is an alternating pole motor 500C. Graph 600 shows the steel losses 605 of the motor compared to the output power 610 of the motor. For example, steel losses refer to the sum of the iron losses of the stator and the rotor at the peak power level. Graph 600 includes curves between steel losses and output power for a conventional outer rotor motor 615, a conventional five-magnet outer rotor motor 620, and an alternating pole motor 625. In some embodiments, the conventional outer rotor motor 615 and the conventional five-magnet outer rotor motor 620 begin to have approximately the same level of steel losses 605 between 250 Watts and 300 Watts. In some embodiments, the steel losses of the conventional outer rotor motor 615 decrease as the output power 610 increases. Similarly, as the output power 610 increases, the steel losses 605 of the alternating pole motor 625 decrease. Conversely, in some embodiments, steel losses 605 in conventional five-magnet outer rotor motor 620 increase as output power 610 increases. In some embodiments, as output power 610 begins to exceed, for example, about 2500 Watts, steel losses in conventional outer rotor motor 615 begin to increase again.

[0089] Figure 7The relationship between steel loss and speed for a conventional outer rotor motor (e.g., motors 500A, 500B) and an alternating pole motor is shown in graphical form. In some embodiments, the alternating pole motor is alternating pole motor 500C. Graph 700 shows steel loss 705 of a motor compared to a motor speed 710 of the motor. Graph 700 includes curves between steel loss and output power for a conventional outer rotor motor 715, a conventional five-magnet outer rotor motor 720, and an alternating pole motor 725. All motors shown in graph 700 start at the same level of steel loss 705 and motor speed 710, where the motor is stopped at zero revolutions per minute (RPM). In some embodiments, as the motor speed 710 increases, the steel loss 705 of the conventional outer rotor motor 715 increases until it reaches about 18,000 RPM and 300 watts of steel loss, at which point the steel loss 705 begins to decrease. Once the motor speed reaches about 28,000 RPM and the steel loss 705 reaches about 175 watts, the steel loss 705 in the conventional outer rotor motor 715 begins to increase again. In some embodiments, as the motor speed 710 increases, the steel losses 705 of the conventional five-magnet outer rotor motor 720 increase until reaching about 28,000 RPM and 540 watts of steel losses, at which point the steel losses 705 begin to decrease. In some embodiments, as the motor speed 710 increases, the steel losses 705 of the alternating pole motor 725 increase until reaching about 20,000 RPM and 125 watts of steel losses, at which point the steel losses level off. The steel losses 705 begin to increase again at about 30,000 RPM, until leveling off again at about 40,000 RPM and 200 watts of steel losses. As shown, the steel losses of the alternating pole motor are significantly lower than those of the conventional outer rotor motor.

[0090] Figure 8 The flux flow in a conventional outer rotor motor and an alternating pole motor is shown. The diagram 800 includes a conventional ten-magnet outer rotor motor 805, a conventional five-magnet outer rotor motor 810, and an outer rotor alternating pole motor 815 (e.g., motor 500C). The conventional ten-magnet outer rotor motor 805 includes magnetic field lines 820 generated by a magnetic north pole 825 and a south pole 830. The conventional five-magnet outer rotor motor 810 has five fewer magnets, and the magnets are highlighted by a portion 835 of the motor 810. In some embodiments, removing these magnets results in a lower flux line density 840 and a longer flux path 845. In conventional outer rotor motors 805, 810, the flux flow is designed to flow radially outward from the stator to the rotor. The flux flows through the air slots between the stator and the rotor, reacts with the magnetic field of the rotor, and then flows back through the opposite pole to complete the magnetic circuit. The strength and position of the magnetic field are usually fixed based on the physical arrangement of the windings and poles.

[0091] In contrast, in an alternating pole outer rotor motor 815, the stator may include two sets of windings for each physical pole. In this configuration, the number of magnetic poles is effectively doubled without increasing the number of physical poles. When the windings are energized, they produce overlapping magnetic fields. The resulting magnetic field is a combination of the magnetic fields produced by each winding. In some embodiments, the flow of magnetic flux in the alternating pole outer rotor motor 815 is more dynamic and can be controlled by varying the current in the windings. As previously described, this enables controlled variations in the magnetic field strength and pattern, and in turn controls the speed and torque characteristics of the alternating pole outer rotor motor 815, as described above. Fig. 9 As shown and described below.

[0092] Similar to the conventional outer rotor motors 805, 810 described previously, the flux path in the alternating pole outer rotor motor 815 still moves radially from the stator to the rotor, but the overlap and adjustability of the magnetic fields in the alternating pole design provides a more versatile and controllable magnetic interaction. In some embodiments, the outer rotor alternating pole motor 815 includes alternating poles at the removed magnets, resulting in a uniform flux density 850 and a shorter flux path 855. In some specific embodiments, the element size of the outer rotor alternating pole motor 815 is designed to ensure that sufficient flux passes and completes the cycle while not allowing the alternating poles to reach saturation.

[0093] Fig. 9 The performance of conventional outer rotor motors and alternating pole motors is shown in a graph. Graph 900 includes a conventional outer rotor motor 905, a conventional five-magnet outer rotor motor 910, and an alternating pole motor 915 (e.g., motor 500C). In some embodiments, the efficiency of each of the three motors 905, 910, 915 starts at approximately the same level, where the output torque is 0 Newton meters (Nm). The efficiency 920 of the conventional outer rotor motor 905 reaches a peak of about 85% at 0.5 Nm. The efficiency 925 of the conventional five-magnet outer rotor motor 910 reaches a peak of about 70% at 0.25 Nm. The efficiency 930 of the alternating pole motor 915 reaches a peak of about 85% at 0.4 Nm. In some embodiments, the efficiency of each of the three motors 905, 910, 915 starts at approximately the same level, where the output torque is 0 Nm. The output power 935 of the conventional outer rotor motor 905 increases to a peak of about 3325 watts at 1.55 Nm. The output power 940 of the conventional five-magnet external rotor motor 910 increases at 0.7 Nm to a peak of about 1900 Watts. The output power 945 of the alternating pole motor 915 increases at 1.15 Nm to a peak of about 2500 Watts.

[0094] In some embodiments, the speeds of the conventional outer rotor motor 905 and the alternating pole motor 915 start at approximately the same level, with a speed of 39,000 RPM. The speed 950 of the conventional outer rotor motor 905 decreases steadily until it reaches about 19,500 RPM and 1.5 Nm, then it begins to decrease at a faster rate until it reaches 0 at 2.25 Nm. The speed 960 of the alternating pole motor 915 decreases until it reaches about 19,500 RPM at 1.2 Nm, then the speed 955 of the motor 915 decreases at a higher rate. The speed 960 of the conventional five-magnet outer rotor motor 910 decreases until it reaches about 19,500 RPM and 0.8 Nm, then the speed 960 decreases at a faster rate until it reaches 0 at about 1.05 Nm. As evidenced by the graph 900, the efficiency of the alternating pole motor 915 is greater than that of the conventional outer rotor motor 905 and the conventional five-magnet outer rotor motor 910 in the light load region 965 (e.g., about 0.65 Nm or less). In the light load region 965, the speed of the conventional five-magnet outer rotor motor 910 is higher, but the speed drops more rapidly as the load level increases. The relative output power of the conventional five-magnet outer rotor motor 910 in the light load region 965 is also slightly higher, but at a lower efficiency.

[0095] Fig.10 and 11 An inner rotor motor 1000 is shown according to some embodiments. The motor 1000 includes a stator lamination stack 1005 and a rotor lamination stack 1010 encapsulated by a first end cap 1015 and a second end cap 1020. In some embodiments, the first end cap 1015 and the second end cap 1020 are molded as a single integral insulator for the stator lamination stack 1005. A shaft 1025 is mechanically connected to the rotor lamination stack 1010 and extends through the rotor lamination stack 1010. A first bearing 1030 is located on a first side 1035 of the shaft 1025, and a second bearing 1040 is located on a second side 1045 of the shaft 1025. A cooling fan 1050 is located on the first side 1035 of the shaft 1025 and surrounds the shaft 1025.

[0096] Fig.11 1 is an exploded view of the motor 1000. The motor 1000 also includes an O-ring 1055 disposed between the cooling fan 1050 and the rotor lamination stack 1010 on the first side 1035 of the shaft 1025. A bushing 1060 is located at the second end 1045 of the shaft 1025. Also shown are two magnets of a plurality of magnets 1065 located within the rotor lamination stack 1010. In some embodiments, the magnets 1065 are glued into the rotor lamination stack 1010 before the rest of the components are pressed onto the shaft 1025.

[0097] Fig.12An inner rotor motor is shown in an airflow test fixture 1200. The motor 1100 is shown mounted to a base plate 1205.

[0098] Fig.13 A portion of an alternating pole motor 1300 is shown according to some specific embodiments. The rotor 1305 includes a lamination stack 1310 and a plurality of magnet slots 1315. A plastic mold 1320 is molded to the lamination stack 1310 to increase the retention force of the lamination stack 1310. The lamination stack 1310 includes an inner lamination portion 1325 and an outer lamination portion 1330. The inner lamination portion 1325 includes a triangular groove portion 1335, which is configured to retain a first retaining portion 1340 of the plastic mold 1320. The first retaining portion 1340 fits into the triangular groove portion 1335, securing the plastic mold 1320 to the inner lamination portion 1325. Likewise, the outer lamination portion 1330 includes an L-shaped portion 1345, which is configured to retain a second retaining portion 1350 of the plastic mold 1320. The L-shaped portion 1345 and the second retaining portion 1350 are configured to secure the outer lamination portion 1330 to the plastic mold 1320. In some embodiments, the plastic mold 1320 is made of a non-magnetic material 1355. For example, in some embodiments, the plastic mold can be made of aluminum, titanium, or other non-magnetic metals or alloys.

[0099] Fig.14 Portions of an alternating pole motor 1400 are shown according to some embodiments. The rotor 1405 includes a lamination stack 1410 and a plurality of magnet slots 1415. A plastic mold 1420 is molded to the lamination stack 1410 to increase the retention force of the lamination stack 1410. The lamination stack 1410 includes an inner lamination portion 1425 and an outer lamination portion 1430. The inner lamination portion 1425 includes a first dovetail groove portion 1435, which is configured to retain a first retaining portion 1440 of the plastic mold 1420. Similar to the previously described rotor 1305, the first retaining portion 1440 fits into the first dovetail groove portion 1435, securing the plastic mold 1420 to the inner lamination portion 1425. The outer lamination portion 1430 includes a second dovetail portion 1445, which is configured to retain a second retaining portion 1450 of the plastic mold 1420. The second dovetail portion 1445 and the second retaining portion 1450 are configured to secure the outer lamination portion 1430 to the plastic mold 1420. In some embodiments, the inner lamination portion 1425 and the outer lamination portion 1430 may contain additional or alternative retaining configurations (eg, overmolding).

[0100] In some embodiments, the rotor 1405 includes different configurations of slot portions designed to secure the inner lamination portion 1425 and the outer lamination portion 1430 to the plastic mold 1420. For example, the inner lamination portion 1425 may include a combination of a first dovetail slot portion 1435 and a first plurality of triangular slot portions 1455. The outer lamination portion may include a second plurality of triangular slot portions 1460. In some embodiments, the plastic mold 1420 includes an outer lamination retaining portion 1465, an inner lamination retaining portion 1470, and a magnet retaining portion 1475.

[0101] Figures 15A to 15C 1 shows an interior permanent magnet motor 1500A, 1500B, 1500C according to some embodiments. In some embodiments, the motor 1500A, 1500B, 1500C is configured for use with a power tool 100. Fig.15A , the motor 1500A includes a built-in permanent magnet configuration. The motor 1500A includes a stator 1505 and a plurality of stator winding slots 1510. The plurality of stator winding slots 1510 are configured to receive a plurality of windings. The motor 1500A also includes a rotor 1515. In some embodiments, the rotor has an outer diameter of 22 mm. The rotor 1515 includes a plurality of slots 1520, and each slot includes a magnet placement portion 1525 configured to receive a magnet 1530. The magnet 1530 includes a length 1535 and a width 1540. In some embodiments, the length 1535 is between 1.0 mm and 12.0 mm, and the width 1540 is between 2.0 mm and 3.0 mm. For example, the magnet 1530 may have a length 1535 of 10 mm and a width of 2.5 mm. The rotor 1515 further includes a lamination stack 1545 and an air slot 1550. In some embodiments, the air slot 1550 is located within the lamination stack 1545, and the air slot 1550 extends along the length of the rotor 1515 in a direction transverse to the axial direction along the rotor 1515. The air slot 1550 includes a length 1555 and a width 1560. In some embodiments, the size of the air slot 1550 or the length 1555 and width 1560 of the air slot 1550 increases or decreases with the size of the magnet 1530. For example, in order to reduce the manufacturing cost of the motor 1500A, the length 1535 of the magnet 1530 can be reduced. Accordingly, the length 1555 of the air slot will increase as the size of the magnet decreases. Alternatively, in some embodiments, the lamination stack 1545 is configured to occupy the space of the reduced magnet length 1535.

[0102] Fig. 15BAn alternative embodiment 1500B of an interior permanent magnet motor according to some aspects is shown. In this embodiment, only two magnets 1530 are inserted into the plurality of slots 1520. The magnets 1530 are configured to have the same magnetic polarization. The replacement poles are alternating poles. Fig. 15C An embodiment 1500C of an interior permanent magnet motor is shown that includes alternating poles 1565, which are located on a lamination stack 1545. Alternating poles 1565 have a length 1570 and a width 1575. In some embodiments, the length 1555 of the air slots 1550 extends in a direction toward the alternating poles 1565 and at an angle of about 45 degrees away from the length 1535 of the magnets 1530. In some embodiments, the length of the air slots 1550 increases as the length of the magnets 1530 decreases. In addition to reducing manufacturing costs, larger air slots can also prevent magnetic saturation from occurring in the material of the motor 1500C. In some cases, magnetic saturation occurs when the magnets 1530 are fully magnetized. By increasing the length 1555 of the air slots 1550, the magnetic flux density can be more effectively managed, thereby reducing the risk of reaching saturation. In some embodiments, the length 1570 and width 1575 of the alternating poles 1565 can be manipulated to control the performance of the motor 1500C.

[0103] Fig.16 Magnetic flux flow in an alternating pole motor and an interior permanent magnet motor is shown according to some embodiments. Diagram 1600 includes a conventional four-magnet interior permanent magnet (IPM) motor 1605 (e.g., motor 1500A), a conventional two-magnet interior permanent magnet (two-magnet IPM) motor 1610 (e.g., motor 1500B), and an optimized alternating pole motor 1615 (e.g., motor 1500C). Conventional IPM motor 1605 includes magnetic field lines 1620 generated by magnetic north poles 1625 and south poles 1630. Conventional two-magnet IPM motor 1610 has fewer magnets, which are highlighted by portion 1635 of motor 1610. In some embodiments, removing these magnets results in lower flux line density 1640 and longer flux paths 1645. In contrast, optimized alternating pole motor 1615 includes alternating poles at the removed magnets, resulting in uniform flux density 1650 and shorter flux paths 1655.

[0104] Fig.17The performance of an alternating pole motor (e.g., motor 1500C) and an interior permanent magnet motor (e.g., motors 1500A, 1500B) according to some specific embodiments is shown in a chart. Chart 1700 includes a conventional interior permanent magnet (IPM) motor 1705 (e.g., motor 1500A), an optimized alternating pole motor (CPM) 1710 (e.g., motor 1500C), and a conventional two-magnet interior permanent magnet (two-magnet IPM) motor 1715 (e.g., motor 1500B). In some embodiments, the efficiency of the three motors 1705, 1710, 1715 starts at approximately the same level, with an output torque of 0 Nm. The efficiency 1720 of the conventional IPM motor 1705 increases to about 85% of the peak at 0.2 Nm. The efficiency 1725 of the optimized CPM motor 1710 increases to about 82% of the peak at 0.15 Nm. The efficiency 1730 of the two-magnet IPM motor 1715 increases to about 65% of the peak at 0.08 Nm. In some embodiments, the output power of the three motors 1705, 1710, 1715 starts at approximately the same level, with an output torque of 0 Nm. The output power 1735 of the conventional IPM motor 1705 increases to a peak of about 1400 watts at 0.53 Nm. The output power 1740 of the optimized CPM motor 1710 increases to a peak of about 1200 watts at 0.4 Nm. The output power 1745 of the two-magnet IPM motor 1715 increases to a peak of about 600 watts at 0.3 Nm.

[0105] The speed 1750 of the conventional IPM motor 1705 decreases in a non-linear direction until it reaches about 40,000 RPM at 0.25 Nm, at which point the speed 1750 begins to decrease at a more linear rate. The speed 1755 of the optimized CPM motor 1710 decreases in a concave downward manner until it reaches about 40,000 RPM at 0.2 Nm, at which point the speed 1755 begins to decrease at a more linear rate. The speed 1760 of the two-magnet IPM motor 1715 decreases sharply at all torques. As evidenced by the graph 1700, the efficiency of the conventional IPM motor 1705 and the optimized CPM motor 1710 is approximately the same in the expected operating region 1765 (e.g., about 0.2 Nm or less). On the other hand, the efficiency of the two-magnet IPM motor 1715 is substantially equal to that of the motors 1705 and 1710 until after 0.05 Nm, at which point the efficiency 1730 of the two-magnet IPM motor 1715 rapidly decreases to below 65%. In the expected operating region 1765, the conventional IPM motor 1705 and the optimized CPM motor 1710 have approximately the same output power. The output power 1745 of the two-magnet IPM motor 1715 diverges from motors 1705 and 1710 at 0.8 Nm and approximately 450 Watts. This indicates that removing two magnets from the conventional IPM motor 1705 significantly reduces efficiency and output power. However, the optimized CPM motor 1710 does not experience a similar drop in performance, indicating that better performance can be achieved within the expected operating region 1765 without using the conventional IPM motor 1705 (e.g., with less magnetic material).

[0106] Fig.18 The relationship between steel loss and speed for an alternating pole motor according to some specific embodiments is shown in graphical form. Graph 1800 shows steel loss 1805 for a conventional interior permanent magnet (IPM) motor (e.g., motor 1500A), steel loss 1810 for an alternating pole motor (CPM) (e.g., motor 1500C), and a conventional two-magnet interior permanent magnet (two-magnet IPM) motor 1815. In general, steel loss for all three motor types increases with increasing speed. In a conventional two-magnet IPM motor, steel loss generally increases linearly, from 40 watts at about 20,000 RPM to 150 watts at 90,000 RPM. In contrast, steel loss 1810 for a CPM initially increases to about 75 watts at 30,000 RPM, then drops to about 65 watts at 42,500 RPM. From there, steel loss 1810 for a CPM increases again until reaching a peak of 110 watts at about 65,000 RPM. The steel losses 1805 of the conventional IPM motor follow a similar pattern, initially increasing to about 70 Watts at 35,000 RPM, then dropping to 65 Watts at 42,500 RPM. From here, the steel losses 1805 of the conventional IPM motor continue to increase until reaching a peak of 120 Watts at about 70,000 RPM.

[0107] Fig.19 The relationship between steel loss and output power for an alternating pole motor according to some specific embodiments is shown in graphical form. Graph 1900 shows steel loss 1905 for a conventional IPM motor (e.g., motor 1500A), steel loss 1910 for a CPM (e.g., motor 1500C), and steel loss 1915 for a conventional two-magnet IPM motor (e.g., motor 1500B). Compared to the conventional IPM motor, the steel loss 1905 for the conventional IPM motor and the steel loss 1910 for the CPM are approximately the same. For an output power ranging from about 300 watts to 1300 watts, the steel loss 1905 for the conventional IPM motor and the steel loss 1910 for the CPM are both between 60 watts and 80 watts.

[0108] Figures 20A to 20B An alternating pole motor 2000A, 2000B is shown according to some specific embodiments. Fig. 20A , the motor 2000A is configured to be used in the power tool 100. The motor 2000A includes a built-in permanent magnet configuration. The motor 2000A includes a stator 2005 and a plurality of stator winding slots 2010. The plurality of stator winding slots 2010 are configured to receive a plurality of windings. The motor 2000A also includes a rotor 2015. The rotor 2015 includes a plurality of slots 2020, and each slot includes a magnet placement portion 2025 configured to receive a magnet 2030. The magnet 2030 has a length 2035 and a width 2040. In some embodiments, the length 2035 of the magnet 2030 is approximately 15 mm and the width is between 1.5 mm and 3.0 mm. The rotor 2015 further includes a lamination stack 2045 and an air slot 2050. The air slot 2050 has a length 2055 and a width 2060. In some embodiments, the size of the air slot 2050, or the length 2055 and width 2060 of the air slot 2050, increases or decreases with the size of the magnet 2030. For example, in order to reduce the manufacturing cost of the motor 2400, the length 2035 of the magnet 2030 can be reduced. Accordingly, the length 2055 of the air slot will increase as the size of the magnet decreases. Alternatively, in some embodiments, the lamination stack 2045 is configured to occupy the space of the reduced magnet length 2035. The rotor 2015 includes alternating poles 2065. The alternating poles have a length 2070 and a width 2075. In some embodiments, the length 2070 or the width 2075 of the alternating poles 2065 can be controlled in order to control the performance of the motor 2000A. For example, as previously described, an alternating pole width of 4 mm can have an impact on torque fluctuations. In some embodiments, the alternating poles 2065 have a width 2075 of 1 mm to 12 mm. For example, as Fig. 20BAs shown, the motor 2000B has an alternating pole width 2075 of, for example, 10.2 mm. Other measurements may also change the performance of the motors 2000A, 2000B. For example, in some embodiments, when the width 2075 of the alternating pole 2065 is increased to 10.2 mm, the length 2055 of the air slots may be reduced.

[0109] Similar to the motors 1500A to 1500C described previously, for the alternating pole motors 2000A, 2000B, the length 2055 of the air slots 2050 extends in a direction toward the alternating poles 2065 and at an angle of about 45 degrees away from the length 2035 of the magnets 2030. In some embodiments, the length 2055 of the air slots 2055 increases as the length 2035 of the magnets 2030 decreases. In addition to reducing manufacturing costs, larger air slots can also prevent magnetic saturation of the materials of the motors 2000A, 2000B. In some cases, magnetic saturation can occur when the magnets 2030 are fully magnetized. By increasing the length 2055 of the air slots 2050, the magnetic flux density can be more effectively managed, thereby reducing the risk of reaching saturation.

[0110] Fig.21 The performance of an alternating pole motor according to some specific embodiments is shown in a graph. Graph 2100 shows a performance comparison between an alternating pole motor having a higher pole width 2110 (e.g., motor 2000B) and an alternating pole motor having a lower pole width 2105 (e.g., motor 2000A). As shown in graph 2100, the efficiency 2115 of the lower width and the efficiency 2120 of the higher width follow approximately the same efficiency curve until reaching an efficiency of about 80% at 0.2 Nm. At this point, the efficiency 2115 of the lower width diverges until the efficiency is about 0% at 0.48 Nm, while the efficiency 2120 of the higher width is 0% at 5.6 Nm. The output power 2125 of the lower width increases to about 1200 watts at 0.35 Nm and then drops to 0 watts at 0.48 Nm. The output power 2130 of the higher width increases to about 1250 watts at 0.33 Nm and then drops to 0 watts at 0.56 Nm. The lower width speed 2135 decreases at approximately the same rate as the higher width speed 2140, with the lower width speed 2135 terminating at 0 RPM and 0.48 Nm, while the higher width speed 2140 terminates at 0 RPM and 0.56 Nm. As can be seen from the graph 2100, the alternating pole motor including the higher pole width 2110 generally has a greater maximum output power and improved efficiency at higher torque levels.

[0111] Fig. 22The torque ripple of conventional IPM motors and alternating pole motors 2000A, 2000B according to some specific embodiments is shown in a chart. Similar to chart 2200, the width of the alternating poles of the alternating pole motor affects the torque ripple. Chart 2200 shows a narrow alternating pole torque ripple 2205. The amplitude of the narrow alternating pole torque ripple 2205 peaks at about 0.35 Nm and 10 degrees, and peaks again at 130 degrees. The amplitude of the narrow alternating pole torque ripple 2205 is lowest at 0.1 Nm and 85 degrees. On the other hand, the amplitude of the wide alternating pole torque ripple 2210 peaks at 0.25 Nm and about 5 degrees, 50 degrees, 125 degrees and 170 degrees. Chart 2200 includes a conventional permanent magnet torque ripple 2215. As shown in chart 2200, as the alternating poles are widened, the overall torque ripple decreases. In some embodiments, reducing torque ripple by widening the alternating poles can result in reduced noise, reduced vibration, or other performance-enhancing effects in the alternating-pole motor.

[0112] Fig.23 An interior permanent magnet motor rotor 2300 is shown according to some embodiments. Rotor 2300 includes a lamination stack 2305. Lamination stack 2305 includes an inner lamination portion 2310 and an outer lamination portion 2315. Rotor 2300 includes a plurality of slots 2320, and each slot includes a magnet receiving portion 2325 configured to receive a magnet 2330. Magnet 2330 includes a length 2335 and a width 2340. Rotor 2300 also includes a rotor sleeve 2345. In some embodiments, rotor sleeve 2345 is made of a carbon fiber material. In some embodiments, the carbon fiber sleeve is made of another material, such as plastic, non-magnetic metal, polycarbonate, etc.

[0113] Figures 24A to 24C FIG. 2 shows interior permanent magnet motor rotors 2400A, 2400B, and 2400C according to some specific embodiments. Fig.24AAs shown, rotor 2400A includes lamination stack 2405. Lamination stack 2405 includes inner lamination portion 2410 and outer lamination portion 2415. Rotor 2400A includes a plurality of slots 2420, and each slot 2420 includes a magnet receiving portion 2425 configured to receive magnet 2430. Magnet 2430 includes a length 2435 and a width 2440. Inner lamination portion 2410 of lamination stack 2405 includes a first axial support portion 2445. Outer lamination portion 2415 of lamination stack 2405 includes a second axial support portion 2450. In some embodiments, plastic mold 2455 is configured to hold inner lamination portion 2410 and outer lamination portion 2415 of lamination stack 2405. The plastic mold 2455 may include a first retaining portion 2460 configured to retain the plastic mold 2455 on the inner lamination portion 2410 and a second retaining portion 2465 configured to retain the plastic mold on the outer lamination portion 2415. The plastic mold 2455 also includes a plate 2470 configured to connect the first retaining portion 2460 and the second retaining portion 2465 to each other, thereby forming a single fastening element to retain the inner lamination portion 2410, the outer lamination portion 2415, and the magnet 2430.

[0114] Fig. 24B A permanent magnet motor rotor 2400B is shown. In this specific embodiment, the rotor 2400B includes a first axial support portion 2445, a first retaining portion 2460, a second retaining portion 2465, and a plate 2470 made of injection molded plastic, and a second axial support portion 2450 and a plate portion 2475 made of stainless steel. The stainless steel plate portion 2475 is configured to be connected to the second axial support portion 2450.

[0115] Fig.24C Another embodiment of a rotor 2400C is shown. In this embodiment, the first axial support portion 2445 and the second axial support portion 2450 are both made of stainless steel and are configured to be connected to the stainless steel plate portion 2475.

[0116] Fig.25An electric motor 2500 is shown according to some specific embodiments. The electric motor 2500 includes a stator 2505 and a plurality of stator winding slots 2510. The stator also includes stator teeth 2513. The plurality of stator winding slots 2510 are configured to receive a plurality of windings wound on the stator teeth 2513. The electric motor 2500 also includes a rotor 2515. The rotor 2525 includes a plurality of permanent magnet slots 2520 configured to receive permanent magnets 2525. The rotor 2515 includes a plurality of magnetic poles 2530. The magnetic poles 2530 have a length 2535 and a width 2540. In some specific embodiments, the length 2535 or the width 2540 of the magnetic poles 2530 is controlled to affect the performance of the electric motor 2500. The effect of the size of the magnetic poles 2530 is shown in Fig.26 The motor 2500 also includes air slots 2545 between the plurality of magnets 2525 and the poles 2530. In some embodiments, the air slots are surrounded by outer ribs 2550 of the lamination stack 2555.

[0117] Fig.26 The performance of an interior permanent magnet (IPM) motor compared to motor 2500 according to some specific embodiments is shown in a chart. The chart includes IPM motor efficiency 2605, IPM motor output power 2615, IPM motor current 2625, and IPM motor speed 2635 compared to motor torque. The chart also includes motor efficiency 2610, motor output power 2620, motor current 2630, and motor speed 2640 compared to motor torque. Chart 2600 also includes a highlighted operating region 2645, in which the IPM motor and motor 2500 both operate normally. As evidenced by chart 2600, the performance of the IPM motor and motor 2500 are similar in operating region 2645. In some embodiments, the magnet mass of the IPM motor shown in chart 2600 is about 55g, while the mass of motor 2500 is reduced by about 28%, and there is no significant impact on the performance of motor 2500 in operating region 2645.

[0118] Fig. 27An interior permanent magnet motor 2700 is shown according to some embodiments. Motor 2700 includes a stator 2705 and a plurality of stator winding slots 2710. The stator also includes stator teeth 2713. The plurality of stator winding slots 2710 are configured to receive a plurality of windings wound on stator teeth 2713. Stator 2705 includes air slots 2714 between the plurality of stator winding slots 2710. Motor 2700 also includes a rotor 2715. Rotor 2715 includes a plurality of permanent magnet slots 2720 configured to receive permanent magnets 2725. Rotor 2715 includes a plurality of alternating poles 2730. Alternating poles 2730 have a length 2735 and a width 2740. In some embodiments, the length 2735 or the width 2740 of alternating poles 2730 is controlled to affect the performance of motor 2700. The effect of the size of the alternating pole 2730 is shown in Fig.28 The motor 2700 also includes air slots 2745 between the plurality of magnets 2725 and the alternating poles 2730. In some embodiments, the air slots 2745 are surrounded by outer ribs 2750 of the lamination stack 2755.

[0119] Fig.28 A graph 2800 is provided showing a performance comparison between an interior permanent magnet motor and an alternating pole motor 2700. The graph includes an IPM motor efficiency 2805, an IPM motor output power 2815, an IPM motor current 2825, and an IPM motor speed 2835 compared to motor torque. The graph also includes an alternating pole motor efficiency 2810, an alternating pole motor output power 2820, an alternating pole motor current 2830, and an alternating pole motor speed 2840 compared to motor torque. The graph 2800 also includes a target operating load 2845 of about 0.19 Nm and a target operating speed 2850 of about 42,000 RPM. As evidenced by the graph 2800, at higher torque levels, the IPM motor exhibits higher efficiency 2805 and output power 2815 compared to the efficiency 2810 and output power 2820 of the motor 2700. However, the performance of the IPM motor and the motor 2700 is similar in the target operating load 2845 region. In some embodiments, graph 2800 shows an IPM motor with a magnet mass of approximately 79 g, which reduces the mass of motor 2700 by approximately 36% without significantly affecting the performance of motor 2700 within the target operating load 2845 region.

[0120] Fig.29An interior permanent magnet motor 2900 is shown according to some specific embodiments. Motor 2900 includes a stator 2905 and a plurality of stator winding slots 2910. Stator 2905 also includes stator teeth 2913. The plurality of stator winding slots 2910 are configured to receive a plurality of windings wound on stator teeth 2913. Motor 2900 also includes a rotor 2915. Rotor 2915 includes a plurality of slots 2920, and each slot 2920 includes a magnet receiving portion 2925 configured to receive a magnet 2930. Magnet 2930 includes a length 2935 and a width 2940. Rotor 2915 further includes a lamination stack 2945, which includes an inner lamination portion 2950 and an outer lamination portion 2955. The inner lamination portion 2950 of lamination stack 2945 includes a first axial support portion 2960. The outer lamination portion 2955 of the lamination stack 2945 includes a second axial support portion 2965. In some embodiments, as previously described and as Figures 24A to 24C As shown, the plastic mold is configured to hold the inner and outer lamination portions. The motor 2900 does not include outer steel ribs that would surround the magnets 2930.

[0121] Fig.30 Graph 3000 is included, which shows a performance comparison between a conventional interior permanent magnet motor and motor 2900. Graph 3000 includes conventional IPM motor efficiency 3005 compared to motor torque, conventional IPM motor output power 3015, conventional IPM motor current 3025, and conventional IPM motor speed 3035. Graph 3000 also includes motor efficiency 3010, output power 3020, motor current 3030, and motor speed 3040 of motor 2900 compared to motor torque. As evidenced by graph 3000, the conventional IPM motor exhibits approximately the same efficiency 3005 as compared to the efficiency 3010 of motor 2900. However, motor 2900 produces approximately 5% more power than the conventional IPM motor.

[0122] Thus, the specific embodiments described herein provide a power tool including an alternating pole motor. Various features and advantages are set forth in the following claims.

Claims

1. An electric tool, characterized in that: The electric tool comprises: a battery pack interface configured to receive a removable and rechargeable battery pack; and An outer rotor motor, the outer rotor motor comprising: a stator including a plurality of stator teeth configured to receive a plurality of stator coils, and a rotor configured to rotate around the stator, the rotor comprising: a first permanent magnet, the first permanent magnet being disposed on an inner surface of the rotor, a second permanent magnet disposed on the inner surface of the rotor, and An air slot is located between the first permanent magnet and the second permanent magnet on the inner surface of the rotor, the air slot having a length and a width, the length of the air slot being greater than a length of the first permanent magnet or the second permanent magnet.

2. The electric tool according to claim 1, characterized in that: The stator comprises at least twelve stator slots; and The rotor comprises at least five rotor poles.

3. The electric tool according to claim 1, characterized in that: The first permanent magnet and the second permanent magnet are made of rare earth metal.

4. The electric tool according to claim 1, characterized in that: Further included are alternating poles disposed in the air slots.

5. The electric tool according to claim 4, characterized in that: The alternating poles are iron poles.

6. The electric tool according to claim 4, characterized in that: The alternating poles comprise a width of approximately 1 mm to 12 mm.

7. The electric tool according to claim 1, characterized in that: The rotor further comprises: a lamination stack comprising an inner lamination portion and an outer lamination portion, and A plastic mold, wherein the plastic mold is configured to improve the retention force of the lamination stack.

8. The electric tool according to claim 7, characterized in that: The inner lamination portion includes a triangular groove portion configured to retain a first portion of the plastic mold to secure the plastic mold to the inner lamination portion.

9. The electric tool according to claim 8, characterized in that: The outer lamination portion includes an L-shaped portion configured to retain the second portion of the plastic mold to secure the outer lamination portion to the plastic mold.

10. The electric tool according to claim 8, characterized in that: The plastic mold is made of non-magnetic material.

11. An electric tool, characterized in that: The electric tool comprises: a battery pack interface configured to receive a removable and rechargeable battery pack; and A motor, comprising: a stator including a plurality of stator teeth configured to receive a plurality of stator coils, and a rotor configured to rotate within the stator, the rotor comprising: a first permanent magnet, the first permanent magnet being disposed in a first slot of the rotor, a second permanent magnet, the second permanent magnet being disposed in a second slot of the rotor, a first alternating pole disposed between the first permanent magnet and the second permanent magnet, the first alternating pole having a first length and a first width, and A second alternating pole is disposed between the first permanent magnet and the second permanent magnet, the second alternating pole having a second length and a second width.

12. The electric tool according to claim 11, characterized in that: The rotor further includes an outer diameter of approximately 22 mm.

13. The electric tool according to claim 11, characterized in that: The first permanent magnet and the second permanent magnet are made of rare earth metal.

14. The electric tool according to claim 11, characterized in that: The first permanent magnet includes a length of about 1 mm to 12 mm and a width of about 2 mm to 3 mm.

15. The electric tool according to claim 11, characterized in that: The rotor further includes a lamination stack and air slots.

16. The electric tool according to claim 15, characterized in that: The air groove is located in the lamination stack and extends along the rotor in a direction transverse to the axial direction.

17. The electric tool according to claim 15, characterized in that: The air slot includes a length extending approximately 45 degrees away from the first permanent magnet in a direction toward the first alternating pole.

18. An electric tool, characterized in that: The electric tool comprises: a battery pack interface configured to receive a removable and rechargeable battery pack; and A motor, comprising: a stator including a plurality of stator teeth configured to receive a plurality of stator coils, and a rotor configured to rotate within the stator, the rotor comprising: Lamination pack, a first air groove, the first air groove being located in the lamination stack and extending along the rotor in a direction transverse to the axial direction, a second air groove, the second air groove being located in the lamination stack and extending along the rotor in a direction transverse to the axial direction, a first permanent magnet, the first permanent magnet being disposed in a first slot of the rotor, a second permanent magnet, the second permanent magnet being disposed in a second slot of the rotor, a first alternating pole disposed between the first permanent magnet and the second permanent magnet, the first alternating pole having a first length and a first width, and A second alternating pole is disposed between the first permanent magnet and the second permanent magnet, the second alternating pole having a second length and a second width.

19. The electric tool according to claim 18, characterized in that: The first air slot includes a first air slot length extending approximately 45 degrees away from the first permanent magnet in a direction toward the first alternating pole, and wherein the second air slot includes a second air slot length extending approximately 45 degrees away from the second permanent magnet in a direction toward the second alternating pole.

20. The electric tool according to claim 19, characterized in that The first air slot length is sized according to the length of the first permanent magnet, and wherein the second air slot length is sized according to the length of the second permanent magnet.

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