Power tool comprising a memory motor

Abstract

Power tools may include a housing. Power tools may include a motor assembly located within the housing, the motor assembly including a stator and a rotor, the stator having winding slots for receiving stator windings, and the rotor including a first magnet positioned at a first distance from a rotational center of the rotor and a second magnet positioned at a second distance from the rotational center of the rotor, wherein the first magnet is made of a rare-earth material and the second magnet is a low-coercivity magnet.

Description

[0001] Related applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 604,387, filed November 30, 2023, and U.S. Provisional Patent Application No. 63 / 612,128, filed December 19, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to power tools. Summary of the Invention

[0003] The power tool of the present invention includes a housing and a motor assembly positioned within the housing. The motor assembly includes a stator and a rotor. The stator has winding slots for receiving stator windings. The rotor includes a first magnet positioned at a first distance from the rotor's rotation center and a second magnet positioned at a second distance from the rotor's rotation center. The first magnet is made of a rare-earth material, and the second magnet is a low-coercivity magnet.

[0004] In some respects, the rotor further includes an outer rotor portion and an inner rotor portion, and the outer rotor portion and the inner rotor portion are connected to each other by rotor ribs that extend from the outer rotor portion to the inner rotor portion in a radial direction away from the rotor's center of rotation.

[0005] In some respects, the rotor further includes an air slot located between the outer rotor portion and the inner rotor portion.

[0006] In some respects, the first magnet extends a first distance into the air slot, and the second magnet extends a second distance into the air slot.

[0007] In some embodiments, the rotor further includes a magnet housing portion that separates the first magnet from the second magnet.

[0008] In some respects, the magnet housing portion includes a first thickness and a second thickness, wherein the first thickness is greater than the second thickness.

[0009] In some respects, the first magnet includes a first arm that extends from the first magnet at an angle between approximately 30 degrees and approximately 45 degrees.

[0010] In some respects, the first magnet includes a second arm extending from the first magnet, and the length of the second arm is approximately half the length of the first arm.

[0011] In some respects, the first magnet includes a first magnet portion and a second magnet portion, the first magnet portion comprising a rare earth material, and the second magnet portion comprising a low coercivity magnet.

[0012] The power tool of this invention includes a housing and a motor assembly positioned within the housing. The motor assembly includes a stator and a rotor, the stator having winding slots for receiving stator windings. The rotor includes a first magnet and a second magnet; the first magnet includes a first arm having a first arm length and a first arm width, and the second magnet includes a second arm having a second arm length and a second arm width. The first arm extends from the first magnet at approximately a 45-degree angle from the first magnet in a radial direction away from the rotor's center of rotation. The first magnet is made of a rare-earth material, and the second magnet is a low-coercivity magnet.

[0013] In some aspects, the rotor further includes an outer rotor portion and an inner rotor portion, and an air slot located between the outer rotor portion and the inner rotor portion, wherein a first magnet extends into the air slot a first distance and a second magnet extends into the air slot a second distance, and wherein the outer rotor portion and the inner rotor portion are connected to each other by rotor ribs extending from the outer rotor portion to the inner rotor portion in a radial direction away from the rotation center of the rotor.

[0014] In some aspects, the rotor further includes a magnet housing portion that separates the first magnet from the second magnet, the magnet housing portion including a first thickness and a second thickness, the first thickness being greater than the second thickness.

[0015] In some respects, the first magnet includes a third arm extending from the first magnet, and the length of the third arm is approximately half the length of the first arm.

[0016] In some respects, the first magnet includes a first magnet portion and a second magnet portion, the first magnet portion comprising a rare earth material, and the second magnet portion comprising a low coercivity magnet.

[0017] The power tool of this invention includes a housing and a motor assembly positioned within the housing. The motor assembly includes a rotor and a stator having winding slots for receiving stator windings. The rotor includes a first air slot, a first magnet configured in a spoke configuration, and a second magnet including an inner radial length and an outer radial length. The inner radial length refers to a first radial distance positioned away from the rotor's center of rotation, and the outer radial length refers to a second radial distance positioned away from the rotor's center of rotation. The first magnet is separated from the second magnet by the second air slot. The first magnet is made of a rare-earth material, and the second magnet is a low-coercivity magnet.

[0018] In some respects, the first air slot separates the first magnet from the outer rib of the rotor.

[0019] In some respects, the rotor further includes a plurality of first magnets and a plurality of second magnets, each of which is separated by a corresponding second air slot.

[0020] In some aspects, the rotor further includes an inner rotor portion, an outer rotor portion, and a plurality of second air slots, wherein a second magnet extends a magnet length from the inner rotor portion to the outer rotor portion, and wherein a first portion of the second magnet is exposed in a first second air slot among the plurality of second air slots, and a second portion of the second magnet is exposed in a second second air slot among the plurality of second air slots.

[0021] In some respects, the outer radial length is greater than the inner radial length.

[0022] In some respects, the power tool further includes a rotor comprising six first magnets configured in a spoke configuration.

[0023] Before explaining any implementation in detail, it should be understood that the implementations are not limited in application to the details of the configuration and arrangement of the components described in the following description or shown in the drawings. The implementations can be practiced or implemented in various ways. Furthermore, it should be understood that the wording and terminology used in this invention are for illustrative purposes and should not be considered limiting. The use of “comprising,” “including,” or “having,” and variations thereof is intended to cover the items listed thereafter and their equivalents, as well as additional items. Unless otherwise stated or limited, the terms “mounted,” “connected,” “supported,” and “coupled,” and variations thereof are used broadly and cover direct and indirect mounting, connection, support, and coupling.

[0024] Unless the context clearly indicates otherwise, the articles “a,” “an,” and “the” should not be interpreted as meaning “one” or “only one.” Instead, these articles should be interpreted 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 articles “a” or “an,” “the” or “said” means “at least one” or “one or more,” unless the usage clearly indicates otherwise.

[0025] Furthermore, it should be understood that implementations may include hardware, software, and electronic components or modules, which, for the purposes of discussion, may be illustrated and described as if most components were implemented solely in hardware. However, those skilled in the art, based on this detailed description, will recognize that in at least one implementation, the electronic aspects may be implemented as software (e.g., stored on a non-transitory computer-readable medium) executable by one or more processing units (such as microprocessors and / or application-specific integrated circuits (“ASICs”)). Therefore, it should be noted that various implementations may be implemented using a plurality of hardware and software-based devices and a plurality of different structural components. For example, “server,” “computing device,” “controller,” “processor,” etc., as described 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) for connection components.

[0026] Relative terms used in conjunction with quantities or conditions, such as “approximately,” “about,” “generally,” etc., will be understood by a person skilled in the art to include the value and have a meaning defined by the context (e.g., the term includes at least the degree of error associated with measurement accuracy, the tolerance associated with a particular value [e.g., manufacturing, assembly, use, etc.]). Such terms should also be considered to disclose a range defined by the absolute values ​​of two endpoints. For example, the expression “about 2 to about 4” also discloses a range of “2 to 4.” Relative terms may refer to a percentage added to or subtracted from the indicated value (e.g., 1%, 5%, 10%).

[0027] It should be understood that although some figures illustrate hardware and software within a particular device, these depictions are for illustrative purposes only. Functions described herein as being performed by a single component can be performed by multiple components in a distributed manner. Similarly, functions performed by multiple components can be combined and performed by a single component. In some embodiments, the illustrated components can be combined or divided into separate software, firmware, and / or hardware. For example, logic and processing can be distributed among multiple electronic processors, rather than residing within and being performed by a single electronic processor. Regardless of how the hardware and software components are combined or divided, they can reside on the same computing device or be distributed among different computing devices connected via one or more networks or other suitable communication links. Similarly, components described as performing specific functions can also perform additional functions not described herein. For example, a device or structure "configured" in a certain way is at least configured in that manner, but may also be configured in a manner not explicitly listed.

[0028] Therefore, in the claims, if the device, method, or system is claimed to include, for example, a controller, control unit, electronic processor, computing device, logic element, module, memory module, communication channel or network, or other elements configured in a certain way to perform, for example, multiple functions, then the claims or claim elements should be interpreted as referring to one or more such elements, any one of which is configured to, for example, implement any one or more of the multiple functions, such that one or more elements together perform multiple functions.

[0029] Other aspects of the invention will become clear from the detailed description and accompanying drawings. Attached Figure Description

[0030] Figure 1 A perspective view of a power tool according to some embodiments is shown.

[0031] Figure 2 The following are illustrated according to some embodiments. Figure 1 A block diagram of the control system of a power tool.

[0032] Figure 3 The diagram illustrates the relationship with some implementation methods. Figure 1 A battery pack used in conjunction with power tools.

[0033] Figure 4 The following are illustrated according to some embodiments. Figure 3 A block diagram of the control system for the battery pack.

[0034] Figure 5 A memory motor according to some embodiments is shown.

[0035] Figure 6 A memory motor according to some embodiments is shown.

[0036] Figure 7 A memory motor according to some embodiments is shown.

[0037] Figure 8 A memory motor according to some embodiments is shown.

[0038] Figure 9 A memory motor according to some embodiments is shown.

[0039] Figure 10 A memory motor according to some embodiments is shown.

[0040] Figure 11 The illustrations show the performance of various motors according to some implementation methods. Detailed Implementation

[0041] Memory motors are a class of permanent magnet (PM) machines with unique characteristics and capabilities. Specifically, the magnetic flux density of the rotor magnets in a memory motor can be adjusted, and the magnets will maintain an adjusted magnetic flux density level. In some cases, memory motors can be configured as pole-changing memory motors (PCMMs) or variable flux memory motors (VFMMs). In contrast, conventional internal permanent magnet (IPM) machines require a separate demagnetizing current to weaken the magnetic field during operation. For example, in some examples, memory motors include low coercivity (LCF) magnets, which enable magnetic field weakening without requiring the constant field-weakening current required in IPM machines. Because memory motors do not rely on a constant field-weakening current, they offer advantages over IPMs by reducing motor complexity and potential energy losses. For example, memory motors can provide a wider operating range and / or improved power and efficiency over light to medium load ranges. Embodiments provided in this invention detail the advantages and applications of memory motors in power tools. In some embodiments, memory motors can be used instead of motors with, for example, an outer stator diameter of 50 mm or greater. In other embodiments, a memory motor can be used instead of a motor with an outer stator diameter of, for example, 40 mm or greater. When the LCF magnet is demagnetized, the memory motor can, for example, increase the speed by approximately 30%. When the LCF magnet is magnetized, the memory motor can, for example, increase the torque by approximately 30%. The LCF magnet can be magnetized by injecting a high-current pulse into the motor drive signal. A short pulse of high current is sufficient to control the magnetization of the LCF magnet.

[0042] Figure 1 A power tool 100 is shown, including a motor (also called a motor assembly) such as a memory motor. The power tool 100 is, for example, a hammer drill including a housing 102. Although... Figure 1 A hammer drill is shown, but in some embodiments, the components described herein are incorporated into other types of power tools, including drill drives, impact drives, impact wrenches, angle grinders, circular saws, reciprocating saws, plate compactors, core drills, rope trimmers, leaf blowers, vacuum cleaners, or other suitable applications where a weak magnetic field can be used for motor operation. Housing 102 includes a handle portion 104 and a motor housing portion 106. 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 connect to or receive a power tool battery pack. In memory motor power tools 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 the memory motor.

[0043] 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 electrically connected to a motor 204, a battery interface 206, a trigger switch 208 (connected to 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 multiple switching FETs), and a gate driver 224 for driving the FET switching module 220. In some embodiments, the motor 204 is a memory motor. The controller 202 includes a combination of hardware and software operable to control the operation of the power tool 100, monitor the operation of the power tool 100, activate one or more indicators 214 (e.g., LEDs), etc.

[0044] The controller 202 includes a plurality of electrical and electronic components that provide power, operation control, and protection to components and modules within the controller 202 and / or the power tool 100. For example, the controller 202 particularly includes a processing unit 226 (e.g., a microprocessor, microcontroller, electronic controller, electronic processor, or other suitable programmable device), a memory 228, an input unit 230, and an output unit 232. The processing unit 226 particularly includes 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 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 and / or data buses (e.g., a common bus 240). For illustrative purposes, Figure 2 The diagram generally illustrates the control and / or data bus. In view of the inventive features described herein, those skilled in the art will understand that one or more control and / or data buses are used for interconnection and communication between various modules, circuits, and components.

[0045] In some implementations, controller 202 is configured to control gate driver 224 to drive motor 204 using sensored or sensorless field-oriented control (“FOC”) motor control technology.

[0046] Memory 228 is a non-transitory computer-readable medium, including, for example, a program storage area and a data storage area. The program storage area and data storage area may include combinations of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card, or other suitable magnetic, optical, physical, or electronic memory devices. Processing unit 226 is connected to memory 228 and executes software instructions that can be stored in RAM of memory 228 (e.g., during execution), ROM of memory 228 (e.g., on a substantially permanent basis), or another non-transitory computer-readable medium such as another memory or disk. Software included in an implementation of power tool 100 may be stored in memory 228 of controller 202. Software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. Controller 202 is configured to retrieve from memory 228 and execute instructions particularly relevant to the control processes and methods described herein. In other configurations, controller 202 includes additional, fewer, or different components.

[0047] 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 and operable for docking with a battery pack (e.g., mechanical, electrical, and communicative connection). For example, by battery pack 300 (see...) Figure 3 Power supplied to the power tool 100 is provided to the power input module 218 via 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 supplying power to the controller 202. The battery pack interface 206 also supplies power to the FET switching module 220 to selectively supply power to the motor 204 by switching the FET switches. The battery pack interface 206 further includes, for example, a communication line 242 for providing a communication line or link between the controller 202 and the battery pack 300.

[0048] Sensing circuit 212 includes one or more current sensors, one or more speed sensors, one or more Hall effect sensors, one or more temperature sensors, etc. Indicator 214 includes, for example, one or more light-emitting diodes (“LEDs”). Indicator 214 can be configured to display the status of power tool 100 or information associated with power tool 100. For example, indicator 214 is configured to indicate measured electrical characteristics of power tool 100, the status of power tool, the status of motor 204, etc. User input module 216 is operatively coupled to controller 202 to, for example, select forward or reverse operating mode, torque and / or speed settings of power tool 100 (e.g., using a torque and / or speed switch), etc. In some embodiments, user input module 216 includes a combination of digital and analog input or output devices required to achieve a desired operating level of power tool 100, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc.

[0049] 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.

[0050] Figure 4 A control system for a battery pack 300 is shown. This 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 shown is connected to one or more battery cells 402 and an interface 404 (e.g., Figure 3 The interface portion 304 of the battery pack 300 is shown. 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 a combination of hardware and software operable to control, in particular, the operation of the battery pack 300, monitor the condition of the battery pack 300, enable or disable the charging of the battery pack 300, enable or disable the discharging of the battery pack 300, etc.

[0051] The controller 400 includes a plurality of electrical and electronic components that provide power, operational control, and protection to components and modules within the controller 400 and / or battery pack 300. For example, the controller 400 particularly includes a processing unit 412 (e.g., a microprocessor, microcontroller, electronic processor, electronic controller, or other suitable programmable device), a memory 414, an input unit 416, and an output unit 418. The processing unit 412 particularly includes 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, memory 414, input unit 416, and output unit 418, as well as various modules or circuits connected to the controller 400, are connected via one or more control and / or data buses (e.g., a common bus 426). For illustrative purposes, Figure 4 The diagram generally illustrates the control and / or data bus. Those skilled in the art will recognize, based on the embodiments described herein, the use of one or more control and / or data buses for interconnection and communication between various modules, circuits, and components.

[0052] Memory 414 is a non-transitory computer-readable medium, including, for example, a program storage area and a data storage area. The program storage area and data storage area may include combinations of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card, or other suitable magnetic, optical, physical, or electronic memory devices. Processing unit 412 is connected to memory 414 and executes software instructions that can be stored in RAM of memory 414 (e.g., during execution), ROM of memory 414 (e.g., on a substantially permanent basis), or another non-transitory computer-readable medium (such as another memory or disk). Software included in the implementation of battery pack 300 may be stored in memory 414 of controller 400. Software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. Controller 400 is configured to retrieve from memory 414 and execute instructions particularly relevant to the control processes and methods described in this invention. In other configurations, controller 400 includes additional, fewer, or different components.

[0053] Interface 404 includes a combination of mechanical components (e.g., rails, grooves, latches, etc.) and electrical components (e.g., one or more terminals), configured and operable to interface (e.g., mechanically, electrically, and communicatively) the battery pack 300 with another device (e.g., a power tool, a battery charger, etc.). For example, interface 404 is configured to communicatively connect to controller 400 via communication line 428.

[0054] Figure 5 A memory motor 500 according to some embodiments is shown. The motor 500 includes a stator 505 and a plurality of stator winding slots 510 for receiving stator windings. The plurality of stator winding slots 510 are configured to receive a plurality of windings wound around stator teeth 515. The motor 500 also includes a rotor 520. The rotor 520 is configured to receive a first magnet 525 and a second magnet 530. In some examples, the first magnet 525 is referred to as an inner magnet, and the second magnet 530 is referred to as an outer magnet. The first magnet 525 is positioned at a first distance 555 from a rotation center 560 of the rotor 520. The second magnet 530 is positioned at a second distance 565 from the rotation center 560 of the rotor 520. In some examples, the second distance 565 is greater than the first distance 555.

[0055] The first magnet 525 includes a first magnet width 535 and a first magnet length 540. The second magnet 530 includes a second magnet width 545 and a second magnet length 550. In some examples, the first magnet width 535 is greater than the second magnet width 545. In some examples, the first magnet length 540 is greater than the second magnet length 550. As shown in the enlarged view 570 of the first magnet length 540 and the second magnet length 550, the first magnet 525 extends from the second magnet 530 by a distance 575. As described above, in some embodiments, the distance 575 is approximately half the difference between the first magnet length 540 and the second magnet length 550. In other words, in some embodiments, twice the distance 575 is approximately equal to the difference between the first magnet length 540 and the second magnet length 550. In some cases, the first magnet 525 and the second magnet 530 are made of different magnetic materials. For example, the first magnet 525 may be a rare-earth magnet (or a rare-earth material), such as a neodymium magnet or a samarium-cobalt magnet, and the second magnet 530 may be an LCF magnet. Magnets 525 and 530 may alternatively be made of aluminum-nickel-cobalt (Alnico), ferrite, or other such magnetic materials. It should be understood that, in alternative embodiments, any magnetic material comprising magnets 525 and 530 may be changed.

[0056] Rotor 520 includes an outer rotor portion 580 and an inner rotor portion 585. The outer rotor portion 580 and the inner rotor portion 585 are connected to each other by rotor ribs 590 extending from the outer rotor portion 580 to the inner rotor portion 585 in a radial direction away from the rotation center 560 of rotor 520. In some examples, rotor 520 further includes an air slot 595 located between the outer rotor portion 580 and the inner rotor portion 585. The air slot 595 is additionally shown in enlarged view 570. In some cases, the rotor includes more than one air slot 595 or a plurality of air slots. In some examples, each of the first magnet 525 and the second magnet 530 extends into at least one air slot 595.

[0057] Figure 6 A memory motor 600 according to some embodiments is shown. The motor 600 includes a stator 605 and a plurality of stator winding slots 610 for receiving stator windings. The plurality of stator winding slots 610 are configured to receive a plurality of windings wound around stator teeth 615. The motor 600 also includes a rotor 620. The rotor 620 is configured to receive a first magnet 625 and a second magnet 630. In some examples, the first magnet 625 is referred to as an inner magnet, and the second magnet 630 is referred to as an outer magnet. In some cases, the rotor 620 includes a magnet housing portion 633 that separates the first magnet 625 from the second magnet 630. In some examples, the magnet housing portion 633 includes a first thickness 634 and a second thickness 636 separating the first magnet 625 from the second magnet 630. In some cases, the first thickness 634 and the second thickness 636 are different thicknesses. For example, the first thickness 634 may be greater than the second thickness 636, or vice versa. A first magnet 625 is positioned at a first distance 655 from the rotation center 660 of the rotor 620. A second magnet 630 is positioned at a second distance 665 from the rotation center 660 of the rotor 620. In some examples, the second distance 665 is greater than the first distance 655.

[0058] The first magnet 625 includes a first magnet width 635 and a first magnet length 640. In some examples, the first magnet 625 includes a first arm 637 having a first arm length 639. The first arm 637 extends from the first magnet 625 at approximately a 45-degree angle and in a radial direction away from the rotation center 660 of the rotor 620. In some examples, the first arm 637 extends from the first magnet 625 at an angle less than 45 degrees. For example, the first arm 637 may extend from the first magnet 625 at an angle between 30 degrees and 45 degrees.

[0059] The second magnet 630 includes a second magnet width 645 and a second magnet length 650. In some examples, the first magnet width 635 is greater than the second magnet width 645. In some examples, the first magnet length 640 is greater than the second magnet length 650. The second magnet 630 includes a second arm 647 having a second arm length 649. An enlarged view 670 of the motor 600 shows a first magnet 625 including a first arm 637 and a first arm length 639, and a second magnet 630 including a second arm 647 and a second arm length 649. Additionally, the rotor 620 includes an outer rotor portion 680 and an inner rotor portion 685. The outer rotor portion 680 and the inner rotor portion 685 are connected to each other between the first arm 637 and the second arm 647 via a magnet housing portion 633. In some embodiments, the motor 600 generates a high reluctance torque, allowing a smaller amount of magnetic material to produce the same torque value as a conventional motor.

[0060] Figure 7 A memory motor 700 according to some embodiments is shown. The motor 700 includes a stator 705 and a plurality of stator winding slots 710 for receiving stator windings. The plurality of stator winding slots 710 are configured to receive a plurality of windings wound around stator teeth 715. The motor 700 also includes a rotor 720. The rotor 720 is configured to receive a first magnet 725 and a second magnet 730. In some examples, the first magnet 725 is referred to as an inner magnet, and the second magnet 730 is referred to as an outer magnet. In some cases, the rotor 720 includes a magnet housing portion 733 that separates the first magnet 725 from the second magnet 730. In some examples, the magnet housing portion 733 includes a first thickness 734 and a second thickness 736 separating the first magnet 725 from the second magnet 730. In some cases, the first thickness 734 and the second thickness 736 are different thicknesses. For example, the first thickness 734 may be greater than the second thickness 736, or vice versa. A first magnet 725 is positioned at a first distance 755 from the rotation center 760 of the rotor 720. A second magnet 730 is positioned at a second distance 765 from the rotation center 760 of the rotor 720. In some examples, the second distance 765 is greater than the first distance 755.

[0061] The first magnet 725 includes a first magnet width 735 and a first magnet length 740. In some examples, the first magnet 725 includes a first arm 737 having a first arm length 739. The first arm 737 extends from the first magnet 725 at approximately a 45-degree angle and in a radial direction away from the rotation center 760 of the rotor 720. In some examples, the first arm 737 extends from the first magnet 725 at an angle less than 45 degrees. For example, the first arm 737 may extend from the first magnet 725 at an angle between 30 degrees and 45 degrees.

[0062] The second magnet 730 includes a second magnet width 745 and a second magnet length 750. In some examples, the first magnet width 735 is greater than the second magnet width 745. In some examples, the first magnet length 740 is greater than the second magnet length 750. The second magnet 730 includes a second arm 747 having a second arm length 749. An enlarged view 770 of the motor 700 shows a first magnet 725 including a first arm 737 and a first arm length 739, and a second magnet 730 including a second arm 747 and a second arm length 749. In some cases, the first arm 737 of the first magnet 725 may extend from the first magnet 725 by a third arm length 741, and the second arm 747 of the second magnet 730 may extend from the second magnet 730 by a fourth arm length 743.

[0063] The lengths of the third arm 741 and the fourth arm 743 are shown in the enlarged view 770 of the motor 700. In some cases, the length of the third arm 741 is approximately half the length of the first arm 739, and the length of the fourth arm 743 is approximately half the length of the second arm 749. Additionally, the rotor 720 includes an outer rotor portion 780 and an inner rotor portion 785. The outer rotor portion 780 and the inner rotor portion 785 are connected to each other between the first arm 737 and the second arm 747 via a magnet housing portion 733. In some embodiments, the motor 700 produces a high reluctance torque, allowing a smaller amount of magnetic material to produce the same torque value as a conventional motor or motor 600.

[0064] Figure 8 A memory motor 800 according to some embodiments is shown. The motor 800 includes a stator 805 and a plurality of stator winding slots 810 for receiving stator windings. The plurality of stator winding slots 810 are configured to receive a plurality of windings wound around stator teeth 815. The motor 800 also includes a rotor 820. The rotor 820 is configured to receive a first magnet 825 and a second magnet 830. In some examples, the first magnet 825 is referred to as an inner magnet, and the second magnet 830 is referred to as an outer magnet. In some cases, the rotor 820 includes a magnet housing portion 833 that separates the first magnet 825 from the second magnet 830. In some examples, the magnet housing portion 833 includes a first thickness 834 and a second thickness 836 separating the first magnet 825 from the second magnet 830. In some cases, the first thickness 834 and the second thickness 836 are different thicknesses. For example, the first thickness 834 may be greater than the second thickness 836, or vice versa. A first magnet 825 is positioned at a first distance 855 from the rotation center 860 of the rotor 820. A second magnet 830 is positioned at a second distance 865 from the rotation center 860 of the rotor 820. In some examples, the second distance 865 is greater than the first distance 855.

[0065] The first magnet 825 includes a first magnet width 835 and a first magnet length 840. In some examples, the first magnet 825 includes a first arm 837 having a first arm length 839. The first arm 837 extends from the first magnet 825 at approximately a 45-degree angle and in a radial direction away from the rotation center 860 of the rotor 820. In some examples, the first arm 837 extends from the first magnet 825 at an angle less than 45 degrees. For example, the first arm 837 may extend from the first magnet 825 at an angle between 30 degrees and 45 degrees. The second magnet 830 includes a second magnet width 845 and a second magnet length 850. In some examples, the second magnet 830 includes a second arm 847 having a second arm length 849. The second arm 847 extends from the second magnet 830 at approximately a 45-degree angle and in a radial direction away from the rotation center 860 of the rotor 820, extending a second arm length 849. In some examples, the second arm 847 extends from the second magnet 830 at an angle less than 45 degrees. For example, the second arm 847 may extend from the second magnet 830 at an angle between 30 degrees and 45 degrees.

[0066] In some cases, the first magnet 825 includes a first magnetic portion 871 and a second magnetic portion 872. In some examples, the first magnet 825 is made of a variety of magnetic materials. For example, the first magnetic portion 871 may be a rare-earth magnet such as neodymium magnet or samarium cobalt magnet, and the second magnetic portion 872 may be an LCF magnet. In some cases, the second magnet 830 includes a third magnetic portion 873 and a fourth magnetic portion 874. Similar to the first magnet 825, the third magnetic portion 873 and the fourth magnetic portion 874 may be made of a variety of magnetic materials. For example, the third magnetic portion 873 may be a rare-earth magnet (or rare-earth material) such as neodymium magnet or samarium cobalt magnet, and the fourth magnetic portion 874 may be an LCF magnet. In some embodiments, the motor 800 prevents the LCF magnet from being remagnetized by the rare-earth magnet. The motor 800 is well-suited for applications requiring higher torque.

[0067] Additionally, rotor 820 includes an outer rotor portion 880 and an inner rotor portion 885. The outer rotor portion 880 and the inner rotor portion 885 are connected to each other via a magnet housing portion 833 between a first arm 837 and a second arm 847. In some embodiments, motor 800 produces high reluctance torque, allowing less magnetic material to produce the same torque value as a conventional motor or motor 600.

[0068] Figure 9A memory motor 900 according to some embodiments is shown. The motor 900 includes a stator 905 and a plurality of stator winding slots 910 for receiving stator windings. The plurality of stator winding slots 910 are configured to receive a plurality of windings wound around stator teeth 915. The motor 900 also includes a rotor 920. The rotor 920 is configured to receive a first magnet 925 and a second magnet 930. In some examples, the first magnet 925 is referred to as an inner magnet, and the second magnet 930 is referred to as an outer magnet. In some cases, the rotor 920 includes a magnet housing portion 933 that separates the first magnet 925 from the second magnet 930. In some examples, the magnet housing portion 933 includes a first thickness 934 and a second thickness 936 separating the first magnet 925 from the second magnet 930. In some cases, the first thickness 934 and the second thickness 936 are different thicknesses. For example, the first thickness 934 may be greater than the second thickness 936, or vice versa. A first magnet 925 is positioned at a first distance 955 from the rotation center 960 of the rotor 920. A second magnet 930 is positioned at a second distance 965 from the rotation center 960 of the rotor 920. In some examples, the second distance 965 is greater than the first distance 955.

[0069] The first magnet 925 includes a first magnet width 935 and a first magnet length 940. In some examples, the first magnet 925 includes a first arm 937 having a first arm length 939. The first arm 937 extends from the first magnet 925 at approximately a 45-degree angle and in a radial direction away from the rotation center 960 of the rotor 920. In some examples, the first arm 937 extends from the first magnet 925 at an angle less than 45 degrees. For example, the first arm 937 may extend from the first magnet 925 at an angle between 30 degrees and 45 degrees. The second magnet 930 includes a second magnet width 945 and a second magnet length 950. In some examples, the second magnet 930 includes a second arm 947 having a second arm length 949. The second arm 947 extends from the second magnet 930 at approximately a 45-degree angle and in a radial direction away from the rotation center 960 of the rotor 920, extending a second arm length 949. In some examples, the second arm 947 extends from the second magnet 930 at an angle less than 45 degrees. For example, the second arm 947 may extend from the second magnet 930 at an angle between 30 degrees and 45 degrees.

[0070] In some cases, the first magnet 925 includes a first magnetic portion 971 and a second magnetic portion 972. In some examples, the first magnet 925 is made of a variety of magnetic materials. For example, the first magnetic portion 971 may be an LCF magnet, and the second magnetic portion 972 may be a rare-earth magnet (or rare-earth material) such as a neodymium magnet or a samarium cobalt magnet. In some cases, the second magnet 930 includes a third magnetic portion 973 and a fourth magnetic portion 974. Similar to the first magnet 925, the third magnetic portion 973 and the fourth magnetic portion 974 may be made of a variety of magnetic materials. For example, the third magnetic portion 973 may be an LCF magnet, and the fourth magnetic portion 974 may be a rare-earth magnet such as a neodymium magnet or a samarium cobalt magnet. In some embodiments, the motor 900 prevents the LCF magnet from being remagnetized by the rare-earth magnet. The motor 900 is well-suited for high-speed applications. The rotor 920 includes an outer rotor portion 980 and an inner rotor portion 985. The outer rotor portion 980 and the inner rotor portion 985 are connected to each other via the magnet housing portion 933 between the first arm 937 and the second arm 947. In some embodiments, the motor 900 produces a high reluctance torque, so that less magnetic material can produce the same torque value as a conventional motor or motor 600.

[0071] Figure 10 A memory motor 1000 according to some embodiments is shown. The motor 1000 includes a stator 1005 and a plurality of stator winding slots 1010 for receiving stator windings. The plurality of stator winding slots 1010 are configured to receive a plurality of windings wound around stator teeth 1015. The motor 1000 also includes a rotor 1020. The rotor includes an outer rotor portion 1021 and an inner rotor portion 1022. The rotor 1020 is configured to receive a first magnet 1025 and a second magnet 1030. In some embodiments, the magnets 1025 and 1030 are configured in a spoke configuration. In some examples, the first magnet 1025 is referred to as the outer magnet, and the second magnet 1030 is referred to as the inner magnet. In some examples, the rotor 1020 includes an outer rib 1033 configured to hold the first magnet 1025. In some embodiments, a first air slot 1034 separates the first magnet 1025 from the outer rib 1033.

[0072] The first magnet 1025 includes a first magnet width 1035 and a first magnet length 1040. In some embodiments, the rotor 1020 includes six first magnets 1025. The second magnet 1030 includes a second magnet length 1045. In some embodiments, the rotor 1020 includes six second magnets 1030. The second magnets 1030 also include an inner radial length 1047 and an outer radial length 1049. The inner radial length 1047 is positioned at a first radial distance 1051 from the rotation center 1060 of the rotor 1020, and the outer radial length 1049 is positioned at a second radial distance 1053 from the rotation center 1060 of the rotor 1020. In some cases, a second air slot 1062 provides a gap between the second magnets 1030 and the first magnets 1025. In some embodiments, for example... Figure 10 In the illustrated embodiment, there are multiple first magnets 1025 and second magnets 1030. In this type of embodiment, a second air slot 1062 is positioned between the multiple second magnets 1030. For example, a second magnet 1030 may be exposed to one second air slot 1062 on one side and another second air slot 1062 on the other side, as shown. Figure 10 As shown.

[0073] In some cases, the first magnet 1025 and the second magnet 1030 are made of different magnetic materials. For example, the first magnet 1025 may be a rare-earth magnet such as neodymium magnet or samarium cobalt magnet, while the second magnet 1030 may be an LCF magnet. In other cases, the first magnet 1025 may be an LCF magnet, while the second magnet 1030 may be a rare-earth magnet such as neodymium magnet or samarium cobalt magnet. In some embodiments, the motor 1000 is designed to utilize flux concentration effects. As a result, higher torque can be generated using less magnetic material.

[0074] Figure 11 This is a graphical representation of efficiency, current, output power, and speed in revolutions per minute (“RPM”) compared to the torque output of several different motors in power tool 100, according to some embodiments. In some examples, the motor represented in graph 1100 is the motor of power tool 100. Graph 1100 includes a representation of the efficiency of several different motors within power tool 100. Curve 1102 shows the efficiency of one type of motor in power tool 100 (e.g., a standard brushless DC motor including internal rare-earth permanent magnets). Curve 1104 shows the efficiency of a second type of motor in power tool 100 (such as motor 500 including Alnico memory magnets). Curve 1106 shows the efficiency of a third type of motor in power tool 100 (such as motor 500 including ferrite memory magnets).

[0075] In some embodiments, curve 1102 represents the efficiency of an internal permanent magnet (“IPM”) motor as the torque value increases. In some embodiments, curve 1104 represents the efficiency of a motor 500 including an Alnico memory magnet as the torque value increases. In some embodiments, for high torque values, the efficiency of the motor 500 including an Alnico memory magnet decreases at a faster rate than that of the IPM motor. In some embodiments, curve 1106 represents the efficiency of a motor 500 including a ferrite memory magnet as the torque value increases. In some embodiments, for high torque values, the efficiency of the IPM motor decreases at a faster rate than that of the motor 500 including a ferrite memory magnet.

[0076] Graph 1100 additionally includes a representation of the current of several different motors within the power tool 100. Curve 1110 shows the current of one type of motor in the power tool 100 (such as an IPM motor). Curve 1112 shows the current of a second type of motor in the power tool 100 (such as a motor 500 including an Alnico memory magnet). Curve 1114 shows the current of a third type of motor in the power tool 100 (such as a motor 500 including a ferrite memory magnet). In some embodiments, curve 1110 represents the current level of the IPM motor as the torque value increases. In some embodiments, curve 1112 represents the current of the motor 500 including an Alnico memory magnet as the torque value increases. In some embodiments, the current of both the IPM motor and the motor 500 including an Alnico memory magnet is approximately equal for any given torque value as the torque increases. In some embodiments, curve 1114 represents the current of the motor 500 including a ferrite memory magnet as the torque value increases. In some implementations, as torque increases, the current of the IPM motor, the motor 500 including Alnico memory magnets, and the motor 500 including ferrite memory magnets are approximately equal to each other until the torque reaches approximately 1.4 Nm.

[0077] Graph 1100 additionally includes a representation of the RPM of several different motors within the power tool 100. Curve 1118 shows the RPM of one type of motor in the power tool 100 (such as an IPM motor). Curve 1120 shows the RPM of a second type of motor in the power tool 100 (such as a motor 500 including an Alnico memory magnet). Curve 1122 shows the RPM of a third type of motor in the power tool 100 (such as a motor 500 including a ferrite memory magnet). In some embodiments, curve 1118 is the RPM level of the IPM motor as the torque value increases. In some embodiments, curve 1120 is the RPM of the motor 500 including an Alnico memory magnet as the torque value increases. In some embodiments, as the torque increases, for a given torque value, the RPM of the motor 500 including an Alnico memory magnet starts at a higher level and then decreases at a faster rate than the RPM of the IPM motor. In some embodiments, curve 1122 represents the RPM of the motor 500, which includes ferrite memory magnets, as the torque value increases. In some embodiments, for a given torque value, the RPM of the motor 500, which includes ferrite memory magnets, starts at a higher level as the torque increases and then decreases at a slower rate than the RPM of an IPM motor. In some embodiments, each motor operates at approximately the same speed at higher torque.

[0078] Graph 1100 additionally includes a representation of the output power (in watts) of several different motors within the power tool 100. Curve 1128 shows the output power of one type of motor in the power tool 100 (such as an IPM motor). Curve 1130 shows the output power of a second type of motor in the power tool 100 (such as a motor 500 including Alnico memory magnets). Curve 1132 shows the output power of a third type of motor in the power tool 100 (such as a motor 500 including ferrite memory magnets). In some embodiments, curve 1128 is the output power level of the IPM motor as the torque value increases. In some embodiments, curve 1130 is the output power level of the motor 500 including Alnico memory magnets as the torque value increases. In some embodiments, curve 1132 is the output power level of the motor 500 including ferrite memory magnets as the torque value increases. In some embodiments, each motor operates at approximately the same output power level.

[0079] Furthermore, each motor configuration described in this invention may include a low-coercivity magnet. In some embodiments, any magnet within the motor may be a low-coercivity magnet. In some embodiments, the LCF magnet is magnetized to obtain a torque greater than approximately 0.2 Nm. Representative characteristics

[0080] Representative features are set forth in the following clauses, which may exist independently or may be combined in any combination with one or more features disclosed in the text and / or drawings of this invention.

[0081] Clause 1. An electric tool comprising: a housing; and a motor assembly positioned within the housing, the motor assembly including a stator and a rotor, the stator having winding slots for receiving stator windings, the rotor including a first magnet positioned at a first distance from a rotation center of the rotor and a second magnet positioned at a second distance from the rotation center of the rotor; wherein the first magnet is made of a rare earth material and the second magnet is a low coercivity magnet.

[0082] Clause 2. The power tool according to Clause 1, wherein: the rotor further comprises an outer rotor portion and an inner rotor portion; and the outer rotor portion and the inner rotor portion are connected to each other by rotor ribs extending from the outer rotor portion to the inner rotor portion in a radial direction away from the center of rotation of the rotor.

[0083] Clause 3. The power tool according to Clause 2, wherein the rotor further includes an air slot located between the outer rotor portion and the inner rotor portion.

[0084] Clause 4. The power tool according to Clause 3, wherein the first magnet extends a first distance into the air slot, and the second magnet extends a second distance into the air slot.

[0085] Clause 5. The power tool according to Clause 1, wherein the rotor further includes a magnet housing portion that separates the first magnet from the second magnet.

[0086] Clause 6. The power tool according to Clause 5, wherein the magnet housing portion includes a first thickness and a second thickness, the first thickness being greater than the second thickness.

[0087] Clause 7. The power tool according to Clause 1, wherein the first magnet includes a first arm that extends from the first magnet at an angle between approximately 30 degrees and approximately 45 degrees for a length of the first arm.

[0088] Clause 8. The power tool according to Clause 7, wherein: the first magnet includes a second arm extending from the first magnet; and the second arm is approximately half the length of the first arm.

[0089] Clause 9. The power tool according to Clause 1, wherein the first magnet comprises a first magnet portion and a second magnet portion, the first magnet portion comprising a rare earth material, and the second magnet portion comprising a low coercivity magnet.

[0090] Article 10. An electric tool comprising: a housing; and a motor assembly positioned within the housing, the motor assembly including: a stator and a rotor, the stator having winding slots for receiving stator windings, the rotor including a first magnet and a second magnet, the first magnet including a first arm having a first arm length and a first arm width, the second magnet including a second arm having a second arm length and a second arm width, wherein the first arm extends from the first magnet at an angle of approximately 45 degrees in a radial direction away from the rotation center of the rotor beyond the first arm length, wherein the first magnet is made of a rare earth material, and the second magnet is a low coercivity magnet.

[0091] Clause 11. The power tool according to Clause 10, wherein the rotor further comprises: an outer rotor portion and an inner rotor portion, and an air slot located between the outer rotor portion and the inner rotor portion, wherein a first magnet extends into the air slot a first distance and a second magnet extends into the air slot a second distance, and wherein the outer rotor portion and the inner rotor portion are connected to each other by rotor ribs extending from the outer rotor portion to the inner rotor portion in a radial direction away from the rotation center of the rotor.

[0092] Clause 12. The power tool according to Clause 10, wherein the rotor further comprises: a magnet housing portion separating the first magnet from the second magnet, the magnet housing portion comprising a first thickness and a second thickness, the first thickness being greater than the second thickness.

[0093] Clause 13. The power tool according to Clause 10, wherein the first magnet includes a third arm extending from the first magnet; and the length of the third arm is approximately half the length of the first arm.

[0094] Clause 14. The power tool according to Clause 10, wherein the first magnet comprises a first magnet portion and a second magnet portion, the first magnet portion comprising a rare earth material, and the second magnet portion comprising a low coercivity magnet.

[0095] Article 15. An electric tool comprising: a housing; and a motor assembly positioned within the housing, the motor assembly including: a stator and a rotor, the stator having a winding slot for receiving stator windings, the rotor including a first air slot, a first magnet configured in a spoke configuration, and a second magnet including an inner radial length and an outer radial length, wherein the inner radial length is a first radial distance from a center of rotation of the rotor, and the outer radial length is a second radial distance from the center of rotation of the rotor, wherein the first magnet is separated from the second magnet by a second air slot, and wherein the first magnet is made of a rare earth material and the second magnet is a low coercivity magnet.

[0096] Clause 16. The power tool according to Clause 15, wherein the first air slot separates the first magnet from the outer rib of the rotor.

[0097] Clause 17. The power tool according to Clause 15, wherein the rotor further comprises: a plurality of first magnets and a plurality of second magnets, wherein each of the plurality of second magnets is separated by a corresponding second air slot.

[0098] Clause 18. The power tool according to Clause 15, wherein the rotor further comprises: an inner rotor portion; an outer rotor portion; and a plurality of second air slots, wherein a second magnet extends a magnet length from the inner rotor portion to the outer rotor portion, and wherein a first portion of the second magnet is exposed to a first second air slot among the plurality of second air slots, and a second portion of the second magnet is exposed to a second second air slot among the plurality of second air slots.

[0099] Clause 19. The power tool according to Clause 15, wherein the outer radial length is greater than the inner radial length.

[0100] Clause 20. The power tool according to Clause 15, wherein the rotor includes six first magnets configured in a spoke configuration.

[0101] Therefore, the embodiments described herein provide power tools including low coercivity magnets. Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention. Various features and advantages are set forth in the appended claims.

Claims

1. An electric tool, comprising: case; and A motor assembly, positioned within the housing, comprising: Stator, the stator having winding slots for receiving stator windings; and The rotor includes a first magnet and a second magnet, wherein the first magnet is positioned at a first distance from the rotation center of the rotor, and the second magnet is positioned at a second distance from the rotation center of the rotor. The first magnet is made of rare earth material, and the second magnet is a low coercivity magnet.

2. The power tool as claimed in claim 1, wherein: The rotor further includes an outer rotor portion and an inner rotor portion; and The outer rotor portion and the inner rotor portion are connected to each other by rotor ribs that extend from the outer rotor portion to the inner rotor portion in a radial direction away from the rotation center of the rotor.

3. The power tool as claimed in claim 2, wherein, The rotor further includes an air slot located between the outer rotor portion and the inner rotor portion.

4. The power tool as claimed in claim 3, wherein, The first magnet extends a first distance into the air slot, and the second magnet extends a second distance into the air slot.

5. The power tool as claimed in claim 1, wherein, The rotor further includes a magnet housing portion that separates the first magnet from the second magnet.

6. The power tool as claimed in claim 5, wherein, The magnet housing portion includes a first thickness and a second thickness, wherein the first thickness is greater than the second thickness.

7. The power tool as claimed in claim 1, wherein, The first magnet includes a first arm that extends from the first magnet at an angle between approximately 30 degrees and approximately 45 degrees.

8. The power tool as claimed in claim 7, wherein: The first magnet includes a second arm extending from the first magnet; and The length of the second arm is approximately half the length of the first arm.

9. The power tool as claimed in claim 1, wherein, The first magnet includes a first magnet portion and a second magnet portion, the first magnet portion comprising rare earth material, and the second magnet portion comprising a low coercivity magnet.

10. An electric tool, comprising: case; and A motor assembly, positioned within the housing, comprising: Stator, the stator having winding slots for receiving stator windings, and Rotor, the rotor comprising: A first magnet, the first magnet including a first arm having a first arm length and a first arm width; and The second magnet includes a second arm having a second arm length and a second arm width. The first arm extends from the first magnet at an angle of approximately 45 degrees in a radial direction away from the rotation center of the rotor, extending beyond the length of the first arm. The first magnet is made of rare earth material, and the second magnet is a low coercivity magnet.

11. The power tool of claim 10, wherein, The rotor further includes: The outer rotor section and the inner rotor section, and An air duct, located between the outer rotor portion and the inner rotor portion. Wherein, the first magnet extends a first distance into the air groove, and the second magnet extends a second distance into the air groove, and The outer rotor portion and the inner rotor portion are connected to each other by rotor ribs, which extend from the outer rotor portion to the inner rotor portion in a radial direction away from the rotation center of the rotor.

12. The power tool as claimed in claim 10, wherein, The rotor further includes: The magnet housing portion separates the first magnet from the second magnet. The magnet housing portion includes a first thickness and a second thickness, wherein the first thickness is greater than the second thickness.

13. The power tool of claim 10, wherein: The first magnet includes a third arm extending from the first magnet; and The length of the third arm is approximately half the length of the first arm.

14. The power tool as claimed in claim 10, wherein, The first magnet includes a first magnet portion and a second magnet portion, the first magnet portion comprising rare earth material, and the second magnet portion comprising a low coercivity magnet.

15. An electric tool, comprising: case; and A motor assembly, positioned within the housing, comprising: Stator, the stator having winding slots for receiving stator windings, and Rotor, the rotor comprising: First air tank; A first magnet, the first magnet being configured in a spoke configuration; and The second magnet includes an inner radial length and an outer radial length. Wherein, the inner radial length is a first radial distance from the rotation center of the rotor, and the outer radial length is a second radial distance from the rotation center of the rotor. The first magnet is separated from the second magnet by a second air gap, and The first magnet is made of rare earth material, and the second magnet is a low coercivity magnet.

16. The power tool as claimed in claim 15, wherein, The first air slot separates the first magnet from the outer rib of the rotor.

17. The power tool as claimed in claim 15, wherein, The rotor further includes: A plurality of first magnets and a plurality of second magnets, wherein each of the plurality of second magnets is separated by a corresponding second air slot.

18. The power tool as claimed in claim 15, wherein, The rotor further includes: Inner rotor section; External rotor section; and Multiple second air slots, Wherein, the second magnet extends the magnet length from the inner rotor portion to the outer rotor portion, and The first portion of the second magnet is exposed to the first second air slot among the plurality of second air slots, and the second portion of the second magnet is exposed to the second second air slot among the plurality of second air slots.

19. The power tool as claimed in claim 15, wherein, The outer radial length is greater than the inner radial length.

20. The power tool as claimed in claim 15, wherein, The rotor includes six first magnets configured in the spoke configuration.

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