Circular saw

Abstract

A circular saw may include a base plate and a blade guard assembly coupled to the base plate, the blade guard assembly including an upper blade guard and a lower blade guard movable between an extended position and a retracted position. A circular saw may include a housing assembly coupled to a saw blade guard assembly, an output shaft, and a saw blade clamp coupled to the output shaft, the saw blade clamp configured to hold a saw blade. The circular saw may include a brushless direct current (DC) motor positioned within the housing assembly and operable to rotate the output shaft. The circular saw may include an electronic controller configured to perform a field weakening operation on the brushless DC motor.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to co-pending U.S. Provisional Patent Application No. 63 / 639,251, filed April 26, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This utility model relates to power tools, and more specifically to circular saws. Background Technology

[0004] Electric cutting tools, such as portable circular saws, can rotate a circular saw blade to cut workpieces made of various materials such as, for example, metal, plastic, fiber, wood, etc. Utility Model Content

[0005] In one aspect, the present invention provides a circular saw configured to operate a saw blade with a diameter of 5-3 / 8 inches. The circular saw includes: a shoe defining a slot and a workpiece contact surface; a saw blade guard assembly coupled to the shoe, the saw blade guard assembly including an upper saw blade guard and a lower saw blade guard, the lower saw blade guard being movable between an extended position where the lower saw blade guard extends through the slot and a retracted position where the lower saw blade guard is positioned above the workpiece contact surface; a housing assembly coupled to the saw blade guard assembly; an output shaft; a saw blade clamp coupled to the output shaft, the saw blade clamp configured to hold the saw blade; a brushless DC motor positioned within the housing assembly and operable to rotate the output shaft; and an electronic controller configured to: set the conduction angle of the brushless DC motor, provide a pulse width modulation (“PWM”) signal with a duty cycle to the brushless DC motor to control the current of the brushless DC motor, and perform field weakening operations. The circular saw is configured to operate using a battery pack with a nominal rated voltage of approximately 12 volts; wherein, in response to the lower saw blade guard residing in the retracted position, the circular saw is fully assembled within a volume defined by a cuboid; wherein the brushless DC motor is configured to generate peak power; and wherein the power-to-volume ratio of the peak power to the volume is greater than or equal to 1.00 watts per cubic inch and less than or equal to 2.00 watts per cubic inch.

[0006] On the other hand, this utility model provides a circular saw configured to operate a saw blade with a diameter of 5-3 / 8 inches. The circular saw includes: a base plate defining a slot and a workpiece contact surface; a saw blade guard assembly coupled to the base plate, the saw blade guard assembly including an upper saw blade guard and a lower saw blade guard, the lower saw blade guard being movable between an extended position where the lower saw blade guard extends through the slot and a retracted position where the lower saw blade guard is positioned above the workpiece contact surface; a housing assembly coupled to the saw blade guard assembly; an output shaft; a saw blade clamp coupled to the output shaft, the saw blade clamp being configured to hold the saw blade; and a brushless DC motor. A brushless DC motor is positioned within a housing assembly and operable to rotate an output shaft; an electronic controller is configured to: set the conduction angle of the brushless DC motor, provide a pulse width modulation (“PWM”) signal with a duty cycle to the brushless DC motor to control the current of the brushless DC motor, and perform a magnetic field weakening operation to modify the conduction angle of the brushless DC motor; the circular saw is configured to operate using a battery pack with a nominal rated voltage of approximately 12 volts; the circular saw has a defined weight; the brushless DC motor is configured to generate peak power; and the power-to-weight ratio of the peak power to the weight is greater than or equal to 105 watts / pound and less than or equal to 150 watts / pound.

[0007] On the other hand, this utility model provides a circular saw configured to operate a saw blade with a diameter of 5-3 / 8 inches. The circular saw includes: a base plate defining a slot and a workpiece contact surface; a saw blade guard assembly coupled to the base plate, the saw blade guard assembly including an upper saw blade guard and a lower saw blade guard, the lower saw blade guard being movable between an extended position in which the lower saw blade guard extends through the slot and a retracted position in which the lower saw blade guard is positioned above the workpiece contact surface; and a housing assembly coupled to the saw blade guard. Components; an output shaft; a saw blade clamp coupled to the output shaft, the saw blade clamp configured to hold the saw blade; and a brushless DC motor, the brushless DC motor being positioned within the housing assembly and operable to rotate the output shaft; wherein the circular saw is configured to operate using a battery pack having a nominal rated voltage of approximately 12 volts; wherein, in response to the lower saw blade guard residing in the retracted position, the circular saw is entirely assembled within a volume defined by a cuboid; wherein the brushless DC motor is configured to generate peak power; wherein the volume is less than or equal to 450 cubic inches (in 3 ); and the power-to-volume ratio of peak power to volume is greater than or equal to 1.00 watts per cubic inch and less than or equal to 2.00 watts per cubic inch.

[0008] Before explaining any implementation in detail, it should be understood that the implementation is 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 implementation 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 restrictive. The use of "comprising," "including," or "having," and variations thereof, is intended to cover the items listed thereafter and their equivalents and 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.

[0009] Unless the context explicitly 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 preceding it introduced by the indefinite article “a” or “an,” “the” and “said” mean “at least one” or “one or more,” unless the usage explicitly indicates otherwise.

[0010] Furthermore, it should be understood that implementations may include hardware, software, and electronic components or modules, which may be shown and described for the purposes of discussion as if most components were implemented solely in hardware. However, those skilled in the art will recognize from this detailed description that, in at least one implementation, the electronic aspects may be implemented in software (e.g., stored on a non-transitory computer-readable medium) that 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 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 the 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 connecting components.

[0011] Related terms used in conjunction with quantities or conditions, such as “about,” “approximately,” “generally,” etc., will be understood by a person skilled in the art to include the stated value and have a meaning prescribed by the context (e.g., the term includes at least the degree of error associated with measurement accuracy, tolerances 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 statement “about 2 to about 4” also discloses a range of “2 to 4.” Related terms may refer to percentages added to or subtracted from the indicated value (e.g., 1%, 5%, 10%).

[0012] It should be understood that although some figures illustrate hardware and software within a particular device, these descriptions are for illustrative purposes only. Functions described in this invention 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 in this invention. For example, a device or structure "configured" in a certain way is at least configured in that way, but can also be configured in a way not explicitly listed.

[0013] 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 as claimed to achieve, for example, any one or more of the multiple functions, such that the one or more elements together perform multiple functions as a set.

[0014] Other aspects of this invention will become apparent upon careful reading of the detailed description and accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a front perspective view of an embodiment of the circular saw according to the present invention.

[0016] Figure 2 yes Figure 1Rear-view perspective of a circular saw.

[0017] Figure 3 Is it possible to... Figure 1 A side view of the saw blade operating together with a circular saw.

[0018] Figure 4 and Figure 5 They are Figure 1 The bottom and top views of the circular saw.

[0019] Figure 6 It is along Figure 1 The line 6-6 was cut Figure 1 A cross-sectional view of a circular saw.

[0020] Figure 7 It is along Figure 1 The line 7-7 was cut Figure 1 Another cross-sectional view of the circular saw.

[0021] Figure 8 It is along Figure 1 The line 8-8 cut Figure 1 Another cross-sectional view of the circular saw

[0022] Figure 9 yes Figure 1 A diagram of a circular saw.

[0023] Figure 10 It is by Figure 1 A block diagram of the magnetic field weakening technique executed by the controller of the circular saw.

[0024] Figure 11 It is a display Figure 1 A graph showing the commutation curve of the brushless motor of a circular saw.

[0025] Figure 12 It shows the combination Figure 10 and Figure 11 A graph depicting the relationship between torque and speed in a magnetic field attenuation technique.

[0026] Figure 13 Is it possible to... Figure 1 A three-dimensional view of a battery pack, such as a low-capacity battery pack, operated in conjunction with a circular saw.

[0027] Figure 14 schematically shown Figure 13 A group of units in a battery pack.

[0028] Figure 15 Is it possible to... Figure 1 A three-dimensional view of a battery pack, such as a high-capacity battery pack, operated in conjunction with a circular saw.

[0029] Figure 16 schematically shown Figure 15 A group of units in a battery pack.

[0030] Figure 17 It shows Figure 1 The circuit diagram of the switching module of the circular saw.

[0031] Figures 18A-18C The diagram shows the methods for determining battery packs (such as...) Figure 15 and 17 A flowchart of the impedance method for a battery pack.

[0032] Figure 19 This illustrates the classification used to control the battery pack. Figure 1 A flowchart of a method for weakening the magnetic field of an electric motor in a circular saw.

[0033] Figure 20-22 They are Figure 1 Side view, front view and top view of a circular saw configured to remove the battery pack and with the lower saw blade guard in the retracted position.

[0034] Figure 23 and 24 They are Figure 1 Front and rear perspective views of a circular saw configured with the battery pack removed and the lower saw blade guard in the retracted position.

[0035] Figure 25 yes Figure 1 Side view of a circular saw. Figure 15 The battery pack is connected to it and the lower saw blade guard is in the retracted position.

[0036] Figure 26 yes Figure 1 Rear-view perspective of the circular saw. Figure 15 The battery pack is connected to it and the lower saw blade guard is in the retracted position.

[0037] Before explaining any embodiment of this utility model in detail, it should be understood that the application of this utility model is not limited to the details of the construction and arrangement of the components described in the following description or shown in the drawings. This utility model is capable of supporting other embodiments and can be practiced or implemented in various ways. Furthermore, it should be understood that the wording and terminology used in this utility model are for illustrative purposes and should not be considered restrictive. In addition, when used in this utility model, the terms "upper," "lower," and other directional terms are not intended to require any particular orientation, but are used only for illustrative purposes. Detailed Implementation

[0038] Figure 1 and Figure 2A power tool in the form of a circular saw 100 is shown. The circular saw 100 includes a base or bottom plate 102, a saw blade guard assembly 104 adjustablely coupled to the bottom plate 102, and a housing assembly 106 coupled to the saw blade guard assembly 104. The circular saw 100 is removably coupled to a saw blade 108. Figure 3 When coupled, the saw blade 108 resides at least partially within the saw blade guard assembly 104. The diameter of the saw blade 108 may be, for example, 5-3 / 8 inches. The circular saw 100 is operable to rotate the saw blade 108 at a high speed to cut workpieces.

[0039] The base plate 102 defines the workpiece contact surface 110. Figure 4 The workpiece contact surface 110 is generally flat and contacts the workpiece during the cutting operation. The base plate 102 also defines a slot 112 through which portions of the saw blade 108 and the saw blade guard assembly 104 can protrude to different degrees.

[0040] See also Figure 1 and Figure 2 The saw blade guard assembly 104 includes an upper saw blade guard 114 and a lower saw blade guard 116 pivotally attached to the upper saw blade guard 114. When the saw blade 108 is coupled to the circular saw 100, the upper saw blade guard 114 is fixedly attached to the housing assembly 106 and covers the upper portion of the saw blade 108. The lower saw blade guard 116 selectively covers the lower portion of the saw blade 108 below the base plate 102, thereby exposing only a small portion of the saw blade 108 when the circular saw 100 is not in use. The lower saw blade guard 116 is rotatable relative to the upper saw blade guard 114 about a rotation axis 118 to selectively expose the lower portion of the saw blade 108. During cutting operations, the lower saw blade guard 116 engages the workpiece, and forward displacement of the circular saw 100 causes the lower saw blade guard 116 to pivot to expose the lower portion of the saw blade 108 to the workpiece.

[0041] The base plate 102 is adjustablely coupled to the upper saw blade guard 114 and supports the circular saw 100 on the workpiece. The base plate 102 is pivotable relative to the upper saw blade guard 114 about a first pivot axis 120 extending parallel to the rotation axis 118. Figure 1 Pivoting. The base plate 102 is pivoted relative to the upper saw blade guard 114 about a first pivot axis 120, causing the base plate to move generally toward or away from the housing assembly 106, and adjusting the degree to which the saw blade 108 protrudes through the slot 112, thereby adjusting the cutting depth of the saw blade 108. The base plate 102 can also pivot relative to the upper saw blade guard 114 about a second pivot axis 124. Figure 1The second pivot axis 124 extends parallel to the rotation axis 118 and perpendicular to the first pivot axis 120. The base plate 102 pivots relative to the upper saw blade guard 114 about the second pivot axis 124 to adjust the angle measured between the saw blade 108 and the workpiece contact surface 110.

[0042] See Figure 1 and Figure 2 The upper saw blade guard 114 includes a guard portion 126 surrounding the upper part of the saw blade 108 and a hub portion 128 fixedly attached (e.g., by threaded fasteners) to the housing assembly 106. The housing assembly 106 includes a first clamshell housing half 130 and a second clamshell housing half 132. The first clamshell housing half 130 is fixedly attached to the hub portion 128, and the second clamshell housing half 132 is fixedly attached (e.g., by threaded fasteners) to the first clamshell housing half 130. The housing assembly 106 also defines a motor housing portion 134 and a handle portion 135. The handle portion 135 includes a main handle portion 136 and a secondary handle portion 138. The motor housing portion 134 contains an electric motor 140 (…). Figure 6 The motor housing portion 134 also houses a printed circuit board assembly 142 (PCBA 142), which controls the operation of the electric motor 140 and other features of the circular saw 100.

[0043] See Figure 2 The main handle portion 136 is connected to the motor housing portion 134 and extends between a first end 144 and a second end 146. The main handle portion 136 supports a trigger 148 and a locking mechanism 150 adjacent to the first end 144, and defines a battery socket 152 at the second end 146. The battery socket 152 selectively and removably receives a battery pack, such as those combined in this invention. Figure 13-16 Battery packs 700 and 800 are described. When coupled to battery socket 152, the battery packs supply power to the electrical components of circular saw 100, such as electric motor 140, printed circuit board assembly 142, etc. The main handle portion 136 further defines a first gripping area 154, which a user can grip to hold, carry, and operate the circular saw 100. A secondary handle portion 138 is connected to the main handle portion 136 and protrudes generally away from the first end 144. The auxiliary handle portion 138 defines a second gripping area 156.

[0044] See Figure 6The electric motor 140 is positioned within a motor housing portion 134 and includes a stator assembly 158, a rotor assembly 160 rotating within the stator assembly 158, and a motor shaft 162 supporting the rotor assembly 160 for co-rotation therewith. In the illustrated embodiment, the electric motor 140 is a brushless direct current (BLDC) electric motor 140, which is electronically commutated by a controller supported on a PCBA 142 as described herein. The stator assembly 158 includes a plurality of coils 164, which are selectively excited by current supplied from a battery pack.

[0045] The stator assembly 158 is fixedly supported by a motor frame 166, which is attached to the upper saw blade guard 114. The motor frame 166 and the upper saw blade guard 114 define corresponding motor bearing recesses 168, 170, which receive corresponding motor bearings 172, 174. The motor bearings 172, 174 support the motor shaft 162 for rotation relative to the stator assembly 158, the upper saw blade guard 114, and the motor frame 166. An output gear 176, such as a pinion, is fixed to (or integrally formed with) the end of the motor shaft 162.

[0046] See Figure 7 and 8 The circular saw 100 also includes an output shaft 178 or a main shaft, which is rotatably supported adjacent to a motor shaft 162. The output shaft 178 supports a driven gear 180, which is fixed to the output shaft 178 for co-rotation. An output gear 176 meshes with the driven gear 180 to transmit torque from the motor shaft 162 to the output shaft 178 and achieve gear reduction. The output shaft 178 supports a saw blade clamp 182, which is operable to selectively secure a saw blade 108 to the output shaft 178. Thus, the output shaft 178 selectively supports and rotatably drives the saw blade 108 during operation of the circular saw 100.

[0047] Figure 9 An electromechanical diagram of a circular saw 100 including a controller 200 is shown. The controller 200 may be supported on a PCBA 142 and electrically and / or communicatively connected to various modules or components of the circular saw 100. For example, the controller 200 shown is connected to a power supply 205 (e.g., one of battery packs 700, 800), a switch bridge 210, an electric motor 140, a Hall effect sensor 220 (also called a Hall sensor), one or more current sensors 225, a user input device 230 (e.g., a trigger 148), other components 235 (e.g., a battery fuel gauge, a work light [e.g., an LED], a current / voltage sensor, etc.), one or more indicators 240 (e.g., LEDs), and a wireless communication controller 245 (e.g., a transceiver) configured to communicate with an external device 250 (e.g., a smartphone, tablet computer, laptop computer, etc.).

[0048] The controller 200 includes a combination of hardware and software operable to control, in particular, the operation of the circular saw 100, control the power supplied to the electric motor 140, etc. In some embodiments, the controller 200 includes a plurality of electrical and electronic components that provide power, operational control, and protection to components and modules within the controller 200 and / or the circular saw 100. For example, the controller 200 particularly includes a processing unit 255 (e.g., a microprocessor, microcontroller, or other suitable programmable device), a memory 260, an input unit 265, and an output unit 270. The processing unit 255 particularly includes a control unit 275, an arithmetic logic unit (“ALU”) 280, and a plurality of registers 285 (in Figure 2 The system is shown as a set of registers and is implemented using a known computer architecture (e.g., a modified Harvard architecture, von Neumann architecture, etc.). Processing unit 255, memory 260, input unit 265, and output unit 270, as well as various modules connected to controller 200, are connected via one or more control and / or data buses (e.g., common bus 290). For illustrative purposes, the data is shown as a set of registers and is implemented using a known computer architecture (e.g., a modified Harvard architecture, von Neumann architecture, etc.). Figure 2 The control and / or data bus is roughly shown in the diagram. Given the embodiments described herein, the use of one or more control and / or data buses for interconnection and communication between various modules and components will be known to those skilled in the art.

[0049] Memory 260 is a non-transitory computer-readable medium that includes, 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 read-only memory (“ROM”), random access memory (“RAM”) (e.g., dynamic RAM [“DRAM”], synchronous DRAM [“SDRAM”], etc.), electrically erasable programmable read-only memory (“EEPROM”), flash memory, hard disk, SD card, or other suitable magnetic, optical, physical, or electronic memory devices. Processing unit 255 is connected to memory 260 and executes software instructions that can be stored in the RAM of memory 260 (e.g., during execution), the ROM of memory 260 (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 circular saw 100 may be stored in memory 260 of controller 200. Software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 200 is configured to retrieve from memory and execute instructions, etc., related to the control of the circular saw 100 described in this invention. In other configurations, the controller 200 includes additional, fewer, or different components.

[0050] Power supply 205 provides DC power to various components of circular saw 100. In some embodiments, power supply 205 is a battery pack (e.g., one of battery packs 700, 800), which is rechargeable and uses, for example, lithium-ion battery cell technology. In some embodiments, circular saw 100 includes, for example, a communication line 295 for providing a communication line or link between controller 200 and power supply 205.

[0051] Each of the Hall effect sensors 220 outputs motor feedback information, such as indications (e.g., pulses) related to when the magnets of the rotor assembly 160 rotate on the surface of the Hall effect sensor 220. Based on the motor feedback information from the Hall effect sensors 220, the controller 200 is able to determine the rotational position, speed, and acceleration of the rotor assembly 160. One or more current sensors 225 output information about the current supplied to the electric motor 140 and / or the circular saw 100.

[0052] The circular saw 100 is configured to operate in various modes. For example, the controller 200 receives user control from user input 230, such as by pressing trigger 148 or actuating any other user input 230 of the circular saw 100. In response to motor feedback information and user control, the controller 200 generates control signals to control the switching bridge 210 (e.g., a FET switching bridge) to drive the electric motor 140. For example, the switching bridge 210 may include a plurality of high-side switching elements (e.g., FETs) and a plurality of low-side switching elements. By selectively enabling and disabling the switching of the switching bridge 210, power from the power supply 205 is selectively applied to the coils 164 of the electric motor 140 to cause rotation of the rotor assembly 160. Although not explicitly shown, one or more current sensors 225 and other components of the circular saw 100 are electrically coupled to the power supply 205, which allows the power supply 205 to supply power to those components.

[0053] In some implementations, the controller 200 also controls other aspects of the circular saw 100, such as recording usage data and communicating with external devices.

[0054] In some embodiments, the circular saw 100 is configured to control the operation of the electric motor 140 based on a detected current supplied by the power supply 205. For example, in some embodiments, the controller 200 is configured to monitor the current supplied by the power supply 205 via information output from one or more current sensors 225. The controller 200 can then control the electric motor 140 based on the detected current supplied by the power supply 205. By monitoring the electric motor 140 and the power supply 205, the controller 200 can control the electric motor 140 with maximum efficiency while achieving the highest available torque with the lowest possible current across the entire range of input voltage (e.g., battery pack voltage) and motor speed.

[0055] Figure 10 A block diagram of current-based field weakening control performed by controller 200 according to some embodiments is shown. Field weakening control techniques for electric motors in power tools are described in more detail in, for example, U.S. Patent Application No. 2024 / 0048085, published February 8, 2024, entitled “POWER TOOL INCLUDING CURRENT-BASED FIELD WEAKENING” and International Patent Application No. WO2023 / 137412, published July 20, 2023, entitled “POWER TOOL CONTROLLING FIELD WEAKENING”, the entire contents of which are incorporated herein by reference.

[0056] exist Figure 10In the illustrated embodiment, controller 200 further includes (e.g., stored in memory 260) a proportional-integral (“PI”) controller 510 and a magnetic field weakening controller 520. As previously described, one or more current sensors 225 sense information regarding the current supplied to electric motor 140 and / or circular saw 100. Controller 200 receives signals indicative of the current supplied to electric motor 140 via one or more current sensors 225. Controller 200 generates a current command 505, which is combined with a sensed current feedback signal from current sensor 225 and provided to PI controller 510. Based on current command 505 and sensed current from current sensor 225, PI controller 510 generates one or more magnetic field weakening reference signals 515 and provides them to magnetic field weakening controller 520. In some embodiments, magnetic field weakening controller 520 determines one or more motor control signals 525 to provide to processing unit 255. For example, one or more motor control signals 525 may indicate a pulse width modulation (“PWM”) signal having a duty cycle and / or conduction angle (e.g., conduction angle in degrees) to be provided to the electric motor 140 to perform control operations. Based on one or more motor control signals 525, processing unit 255 determines, for example, a PWM signal having a duty cycle and conduction angle to be applied to the electric motor 140. A sensed current feedback signal, along with a subsequently generated current command 505, is provided to PI controller 510 to initiate subsequent control operations. In some embodiments, the subsequent magnetic field weakening operation includes a first change in the PWM signal applied to the electric motor 140. In some embodiments, controller 200 receives a sensed current feedback signal via one or more current sensors 225, which indicates the current supplied by the electric motor 140 during control operations when the conduction angle is used to increase the current applied to the electric motor 140. This current feedback signal, along with the subsequently generated current command 505, is again provided to PI controller 510 to initiate subsequent control operations. In some implementations, the subsequent magnetic field weakening operation includes a first change in the conduction angle applied to the electric motor 140 (e.g., an increase in the conduction angle).

[0057] In some implementations, the conduction angle of the electric motor 140 can be varied to increase the conduction angle. Typically, the conduction angle applied to a BLDC motor (e.g., electric motor 140) is set to a default value (e.g., approximately 105°, approximately 120°, between 90° and 120°, etc.). However, to increase speed, for example by weakening it with a magnetic field, the conduction angle for a given phase can be increased to a maximum value, such as 180°.

[0058] Figure 11An embodiment of commutation applied to a BLDC motor such as electric motor 140 is shown. During operation of electric motor 140, a back electromotive force (“BEMF”) 600 is generated and is typically tracked using a conduction angle 605. Figure 6 As shown, the conduction angle 605 can be approximately 120° and can be applied to either a high-side switch (such as a high-side FET) or a low-side switch (such as a low-side FET) as described above to drive the electric motor 140. Figure 11 As further shown, to increase speed, the conduction angle 605 can be increased from 120° to a maximum value, such as 180°, via magnetic field attenuation (as shown by the optional conduction region 610). Furthermore, as shown by the phase advance line 615, the conduction angle 605 can be shifted to occur earlier in the conduction cycle (i.e., phase advance). In some embodiments, the controller 200 can use a single magnetic field attenuation method or a combination of magnetic field attenuation methods of this invention to control the electric motor 140.

[0059] Figure 12 This is a graph 650 showing the relationship between torque and speed (i.e., revolutions per minute ("RPM") of motor 140 for high-capacity battery packs (e.g., battery pack 800 of this invention) and low-capacity battery packs (i.e., battery pack 700 of this invention). Specifically, graph 650 shows an increase in torque of motor 140 as the speed of motor 140 decreases substantially. Line 655 shows the relationship between torque and speed during normal operation of circular saw 100 with high-capacity battery packs when magnetic field weakening techniques are not implemented. Line 660 shows the relationship between torque and speed during operation with high-capacity battery packs while implementing current-based magnetic field weakening techniques of this invention, wherein, for example, the conduction angle is increased (or maximized) and the current is limited. Line 660 may represent a maximum power magnetic field weakening technique. Figure 12 As shown, compared to conventional operation without magnetic field weakening (represented by line 655), the power output of motor 140 (which can be considered as the product of speed and torque) increases approximately for line 660. This increase in maximum power of motor 140 is achieved through magnetic field weakening technology, at the cost of reduced efficiency and faster depletion of the battery pack throughput. Line 665 shows the relationship between torque and speed during normal operation of the circular saw 100 with a low-capacity battery pack when magnetic field weakening technology is not implemented. Due to the lower capacity of the low-capacity battery pack, controller 200 may not implement maximum power magnetic field weakening technology to maintain battery capacity and extend operating time.

[0060] Additional or alternative techniques for controlling magnetic field weakening in power tools can also be implemented. For example, magnetic field weakening can be controlled based on characteristics of the battery pack, such as impedance or nominal capacity. Such magnetic field weakening control techniques for electric motors in power tools are described in more detail, for example, in International Patent Application No. WO2023 / 137412, published on July 20, 2023, entitled “POWER TOOL CONTROLLING FIELD WEAKENING”, the entire contents of which are incorporated herein by reference.

[0061] In other embodiments, the controller 200 may alternatively be based on the Hall effect sensor 220 ( Figure 9 Instead of the current-based magnetic field weakening control described herein, the controller 200 uses the input of a current-based input to execute a position-based magnetic field weakening control scheme. In these embodiments, the controller 200 directly monitors the position of the rotor assembly 160 and, based on the rotor position, executes the position-based magnetic field weakening control scheme by operating the switch bridge 210 to change or increase the conduction angle.

[0062] Figure 13 A rechargeable battery pack 700 according to some embodiments is shown. The rechargeable battery pack 700 includes a housing 705 and a device interface portion 710 for connecting the rechargeable battery pack 700 to a device (e.g., a power tool, a circular saw 100, etc.). The rechargeable battery pack 700 includes a plurality of battery cells 715 within the housing 705.

[0063] Figure 14 A group 720 of battery cells 715 is shown, comprising, for example, six individual battery cells 715. The battery cells 715 may be housed within a housing 705 of a rechargeable battery pack 700. In some embodiments, the rechargeable battery pack 700 includes more or fewer than three battery cells within the housing 705. In the illustrated embodiment, the battery pack 700 is a “3S” or “3S1P” battery pack with three cells 715 connected in series. The battery pack 700 may have a nominal rated voltage of approximately 12 volts (V) and a nominal rated capacity of 2.5 ampere-hours (Ah). In some embodiments, the nominal rated voltage of approximately 12V may include 12V plus or minus 25% of the nominal rated voltage. For the purposes of this invention, the battery pack 700 may be considered a low-capacity battery pack.

[0064] Figure 15 A battery pack 800 according to some embodiments is shown. The battery pack 800 includes a housing 805 and a device interface portion 810 for connecting the rechargeable battery pack 800 to a device (e.g., a power tool, a circular saw 100, etc.). The rechargeable battery pack 800 includes a plurality of battery cells 815 within the housing 805.

[0065] Figure 16 A group 820 of battery cells 815 is shown, comprising, for example, six individual battery cells 815. The battery cells 815 may be located within a housing 805 of a rechargeable battery pack 800. In some embodiments, the rechargeable battery pack 800 includes more or fewer than six battery cells within the housing 805. In the illustrated embodiment, the battery pack 800 is a “3S2P” battery pack having two groups of batteries 815 connected in parallel, with three batteries 815 in each group connected in series. The battery pack 800 may have a nominal rated voltage of 12 volts (V) and a nominal rated capacity of 5 ampere-hours (Ah). In some embodiments, the nominal rated voltage of approximately 12V may include 12V plus or minus 25% of the nominal rated voltage. When used in this invention, the battery pack 800 can be considered a high-capacity battery pack.

[0066] Figure 17 A circuit diagram 900 of the switch bridge 210 is shown. The switch bridge 210 includes a number of high-side power switching elements 1002 (high-side FETs 1002) and a number of low-side power switching elements 1004 (low-side FETs 1004). As described above, the controller 200 provides control signals to control the high-side FETs 1002 and low-side FETs 1004 to drive the electric motor 140 based on motor feedback information and user control. Circuit diagram 900 further shows a battery pack (e.g., such as battery pack 700, 800) electrically coupled to a battery socket 152, which is electrically connected to the switch bridge 210.

[0067] Figures 18A-18C A method 3400, executed by controller 200, is shown to determine the impedance of a battery pack (e.g., battery pack 700, 800) coupled to battery socket 152. Controller 200 activates circular saw 100 (step 3405) to initialize method 3400. Controller 200 receives or measures the battery pack voltage, and controller 200 determines or calculates the initial battery pack voltage V. start (Step 3410). The controller 200 then receives one or more signals from one or more sensors (e.g., Hall effect sensor 220) related to the rotational position of the rotor assembly 160. Data corresponding to the one or more signals is stored in memory 260 for determining the rotor position (step 3415). Using the data received from the Hall effect sensor 220, the controller 200 initiates power supply to one or more high-side FETs 1002 and one or more low-side FETs 1004, thereby allowing current to flow through the motor 140 (step 3420). A delay is then established to allow current to flow through the system (step 3425). The delay allows the current to rise to a level that can be reliably read with sufficient resolution. Figure 18BA continuation of method 3400 performed by controller 200 is shown. After implementing a delay at step 3425, controller 200 samples the current-sensing input to the analog-to-digital converter (“ADC”) and receives or measures a second voltage (e.g., samples the voltage-sensing input to the ADC). In some embodiments, multiple samples are acquired in a single measurement. Controller 200 then uses the sampled current-sensing input to calculate the current I of the rechargeable battery pack. bat Second voltage measurement result V end (Step 3430). Then, controller 200 turns off low-side FET 1004 to allow freewheeling current in high-side FET 1002 (step 3435). Another delay is used to allow high-side power switch 1002 to freewheeling current for a certain amount of time (step 3440).

[0068] Using the initial battery voltage from step 3410, the second battery voltage from step 3430, and the calculated current of the rechargeable battery pack 12 from step 3430, the controller 200 is configured to determine the impedance of the rechargeable battery pack (step 3445). The impedance of the rechargeable battery pack 12 can be calculated by the controller 200 using, for example, equation (1).

[0069]

[0070] Although equation (1) provides one example of how to determine battery pack impedance, other techniques for determining battery pack impedance can also be used.

[0071] In another embodiment of estimating battery pack impedance, the rate of voltage drop and the rate of current rise can be correlated with the system's inductance. The voltage drop is measured at least twice, and a fixed inductance is assumed. In another embodiment of estimating battery pack impedance, the approximate impedance of the battery pack can also be estimated using only the measured current. In yet another embodiment of estimating battery pack impedance, the integral of the measured current over time can be used to find an estimate of the battery pack impedance. Similarly, the integral of the voltage over time can be used to find an estimate of the battery pack impedance. Similarly, the derivative of the rising current and / or the derivative of the falling voltage can also be used to find an estimate of the battery pack impedance.

[0072] In another implementation of estimating battery pack impedance, during surge current techniques, voltage and current samples are measured to perform slope calculations to find the impedance. The slope calculations can be fed into another algorithm (e.g., a neutral network, filter function, etc.) to derive multiple aspects of the impedance (e.g., resistance, capacitance, inductive load, etc.). Furthermore, surge techniques can be used with multiple surge spikes, and the results can be combined for a more accurate output.

[0073] Figure 18CThis is a continuation of method 3400. In step 3450, controller 200 determines the measured battery pack impedance Z. pack Whether it is less than a predetermined value. If the impedance calculated at step 3450 is greater than or equal to a predetermined value (e.g., a value of 50 to 80 milliohms), then controller 200 is configured to determine that the rechargeable battery pack is a first type of battery pack (step 3455). The first type of battery pack may correspond to battery pack 800, i.e., a high-capacity battery pack. If the impedance calculated at step 3450 is less than a predetermined value, then controller 200 is configured to determine that the rechargeable battery pack is a second type of battery pack (step 3460). The second type of battery pack may correspond to battery pack 700, i.e., a low-capacity battery pack. In some embodiments, multiple impedance thresholds are included for determining the type of battery pack. In some embodiments, impedance is a continuous parameter used to identify the type of battery pack (e.g., using a lookup table). In another embodiment, the voltage and / or current of the system can be measured by the battery pack. In other embodiments, the voltage and / or current measurement results can be transmitted to a tool (e.g., via a digital or analog interface). In other embodiments, the battery pack can self-calculate its own impedance. The battery pack can transmit the self-calculated impedance of the battery pack to the power tool. In another implementation, the power tool can calculate the impedance of the battery pack and then transmit the calculation results to the battery pack.

[0074] Figure 19A method 3600 executed by a controller 200 of a circular saw 100 is illustrated. The circular saw 100 is energized (step 3605) to initialize method 3600 via the controller 200. For example, the circular saw 100 can be activated by detecting the activation of a trigger 148, which causes the attached battery pack to supply power to the circular saw 100. The controller 200 then determines parameters of the rechargeable battery pack (step 3610), for example, using one of the methods described above. Parameters of the rechargeable battery pack may include, for example, battery pack impedance, battery pack capacity (e.g., ampere-hour capacity), battery pack state of charge (SOC), battery pack identifier, etc. For example, the controller 200 may determine the impedance or type of the rechargeable battery pack according to the method 3400 of this invention. The controller 200 then assigns a category to the rechargeable battery pack based on the parameters determined in step 3610 (step 3615). The category of the rechargeable battery pack may be, for example, a high-capacity battery category or a low-capacity battery category. In some implementations, when the battery pack's capacity exceeds, for example, a 3 Ah threshold, the controller 200 classifies the battery pack as a high-capacity battery. Thus, the controller 200 determines that battery pack 800 is a high-capacity battery pack according to method 3600. In other implementations, when the battery pack's capacity is less than or equal to the 3 Ah threshold, the controller 200 classifies the battery pack as a low-capacity battery. Therefore, the controller 200 determines that battery pack 700 is a low-capacity battery pack according to method 3600. In various implementations, the classification is related to predetermined parameters of the rechargeable battery.

[0075] Then, controller 200 controls the magnetic field weakening of the electric motor 140 of the circular saw 100 based on the classification of the rechargeable battery pack (e.g., using one of the methods described above) (step 3620). For example, controlling the magnetic field weakening of the electric motor 140 includes enabling, disabling, dynamically modifying, or setting a fixed amount of magnetic field weakening applied to the electric motor 140. In one instance, if controller 200 determines that the rechargeable battery pack is classified as a high-capacity category (e.g., battery pack 800), controller 200 enables the magnetic field weakening of motor 140. For example, controller 200 may implement the present invention in combination with... Figure 12 The described maximum power magnetic field weakening technique aims to achieve a greater maximum power output for motor 140 because the reduced efficiency is acceptable for high-capacity battery packs. In another instance, if controller 200 determines that the rechargeable battery pack is classified as low-capacity, controller 200 disables magnetic field weakening of motor 140. In yet another instance, if controller 200 determines that the rechargeable battery pack is classified as low-capacity, magnetic field weakening can still be implemented, but controller 200 can enable a weaker magnetic field weakening of motor 140.

[0076] See Figure 20-24Compared to most conventional circular saws, the circular saw 100 has a relatively compact arrangement or small "shape factor," as conventional circular saws are configured to work using a saw blade 108 with a diameter of approximately 5-3 / 8 inches. In other words, the circular saw 100 occupies a relatively small three-dimensional space compared to this similar conventional circular saw. For example, Figure 20-24 A circular saw 100 is shown, arranged to remove the battery pack and with the lower saw blade guard 116 moved to a fully retracted position, where the lower saw blade guard 116 is positioned above the workpiece contact surface 110. In this configuration, the circular saw 100 can be fully residing within the workpiece contact surface 110. Figure 23 and 24 The rectangular parallelogram 4000 shown is within the three-dimensional space defined by the rectangle.

[0077] In the illustrated embodiment, the rectangular parallelogram 4000 has approximately 424 cubic inches (in) 3 The volume 4005 of the rectangular parallelogram 4000 is 4005. In some embodiments, the volume 4005 of the rectangular parallelogram 4000 may be less than or equal to 550 cubic inches to maintain a compact arrangement. In other embodiments, to maintain a compact arrangement, the volume 4005 of the rectangular parallelogram 4000 may be less than or equal to 500 cubic inches, or less than or equal to 475 cubic inches, or less than or equal to 450 cubic inches, or less than or equal to 425 cubic inches, or less than or equal to 424 cubic inches. In a further embodiment, to maintain a compact arrangement, the volume 4005 of the rectangular parallelogram 4000 may be less than or equal to 550 cubic inches and greater than or equal to 300 cubic inches. In other embodiments, the volume 4005 may be less than or equal to 500 cubic inches and greater than or equal to 350 cubic inches. In a further embodiment, the volume 4005 may be less than or equal to 450 cubic inches and greater than or equal to 400 cubic inches.

[0078] like Figure 20-24 As shown, the rectangular parallelogram 4000 is defined by six planes arranged in parallel pairs. These six planes include the first XZ plane 4010, the second XZ plane 4015, the first XY plane 4020, the second XY plane 4025, the first YZ plane 4030, and the second YZ plane 4035.

[0079] like Figure 20 and Figure 21As shown, the first XZ plane 4010 is defined by the workpiece contact surface 110 of the base plate 102. The second XZ plane 4015 extends parallel to the first XZ plane 4010 and is tangent to a first vertex 4040 of the circular saw 100 defined on the handle portion 135. The first vertex 4040 is the point on the surface of the circular saw 100 furthest from the first XZ plane 4010 along a direction perpendicular to the first XZ plane 4010. Although in the illustrated embodiment the first vertex 4040 is defined by the housing assembly 106, in other embodiments, the first vertex 4040 may be defined by another functional component of the circular saw 100 (e.g., a guard assembly, etc.). A first dimension or height 4045 of the circular saw 100 is measured between and perpendicular to the first XZ plane 4010 and the second XZ plane 4015. In the illustrated embodiment, the height 4045 is 6.8125 inches (in).

[0080] like Figure 20 and 22 As shown, the first XY plane 4020 extends tangentially to the leading edge 4050 of the saw blade 102 in the cutting direction of the circular saw 100. The first XY plane 4020 is also perpendicular to the first XZ plane 4010. The second XY plane 4025 extends parallel to the first XY plane 4020 and is tangential to the second vertex 4055 of the circular saw 100, which is defined at or near the battery socket 152 on the housing assembly 106. The second vertex 4055 is the point on the surface of the circular saw 100 that is furthest from the first XY plane 4020 along a direction perpendicular to the first XY plane 4020. Although the second vertex 4055 is defined by the housing assembly 106 in the illustrated embodiment, in other embodiments, the second vertex 4055 may be defined by another functional component of the circular saw 100 (e.g., a protective component, a base plate, etc.). The second dimension or length 4060 of the circular saw 100 is measured between and perpendicular to the first XY plane 4020 and the second XY plane 4025. In the illustrated embodiment, the length 4060 is 10.8125 inches (in).

[0081] like Figure 21 and 22As shown, the first YZ plane 4030 extends tangentially to the side edge 4065 of the base plate 102. The side edge 4065 extends generally parallel to the longitudinal axis of the base plate 102, adjacent to the saw blade guard assembly 104, and away from the housing assembly 106. The first YZ plane 4030 is also perpendicular to the first XZ plane 4010 and the first XY plane 4020. The second YZ plane 4035 extends parallel to the first YZ plane 4030 and is tangential to the third vertex 4070 of the circular saw 100, which is defined at or near the motor housing portion 134 on the housing assembly 106. The third vertex 4070 is the point on the surface of the circular saw 100 that is furthest from the first YZ plane 4030 along a direction perpendicular to the first YZ plane 4030. Although the third vertex 4070 is defined by the housing assembly 106 in the illustrated embodiment, in other embodiments, the third vertex 4070 may be defined by another functional component of the circular saw 100 (e.g., a protective assembly, a base plate, etc.). The third dimension or width 4075 of the circular saw 100 is measured between and perpendicular to the first YZ plane 4030 and the second YZ plane 4035. In the illustrated embodiment, the width 4075 is 5.75 inches (in). In some embodiments, the width 4075 is less than or equal to 6.00 inches.

[0082] As discussed in this invention, the circular saw 100 is configured to work in conjunction with a controller 200, which implements magnetic field weakening control techniques to regulate the speed, torque, and / or power output by the electric motor 140. Therefore, the electric motor 140 is able to operate under the control implemented by the controller 200 (as discussed in this invention). Figure 12 The maximum power field weakening technique described herein outputs a peak power P of approximately 505 watts to maximize the power output of the electric motor (e.g., by increasing the conduction angle and / or regulating the current as described in this invention). In some embodiments, the peak power P is greater than or equal to 500 watts. The 505-watt peak power P can be achieved using battery pack 800 (i.e., a high-capacity battery pack). However, when the circular saw 100 operates with battery pack 700 (i.e., a low-capacity battery pack), the peak power P may be lower because, when using a low-capacity battery pack, the controller 200 may not implement the maximum power field weakening technique to save power throughput and increase tool uptime. Whether a high-capacity or low-capacity battery pack is connected to the circular saw 100 can be determined by the controller 200 according to method 3600 described in this invention or according to other methods.

[0083] In other embodiments, the circular saw 100 can operate using an improved high-capacity battery pack (not shown) that has improved characteristics compared to the battery pack 800 described in this invention. For example, the improved high-capacity battery pack may have the same capacity as the battery pack 800 (e.g., 5 Ah), but may have a greater peak power delivery. In other embodiments, both the capacity and peak power delivery of the improved high-capacity battery pack may be greater than those of the battery pack 800. When operated using the improved high-capacity battery pack, the circular saw 100 is configured to operate using a controller 200 implementing magnetic field weakening control technology to regulate the speed, torque, and / or power output of the electric motor 140. Thus, using the improved high-capacity battery pack, the electric motor 140 can be operated by the controller 200 (in conjunction with this invention) Figure 12 The maximum power magnetic field attenuation technique described herein outputs a peak power P of approximately 563 watts to maximize the power output of the electric motor (e.g., by increasing the conduction angle and / or regulating the current, as described in this invention). In some embodiments, the peak power P is greater than or equal to 550 watts.

[0084] As discussed in this utility model, in Figure 20-24 In the configuration of the circular saw 100 shown, that is, when the battery pack and saw blade 108 are removed, the circular saw 100 can reside completely in the position provided by the battery pack. Figure 23 and 24Within the three-dimensional space defined by the rectangular parallelogram 4000 shown, the circular saw 100 can have a peak power P to volume 4005 ratio (i.e., power-to-volume ratio PV). In the illustrated embodiment, when operating with a high-capacity battery pack such as the battery pack 800 described herein, the power-to-volume ratio PV is approximately 1.19 watts per cubic inch. In another embodiment, when operating with an improved high-capacity battery pack as described herein, the power-to-volume ratio PV is approximately 1.33 watts per cubic inch. In other embodiments, the power-to-volume ratio PV can be greater than or equal to 1.19 watts per cubic inch. In a further embodiment, the power-to-volume ratio PV can be greater than or equal to 1.00 watts per cubic inch and less than or equal to 2.00 watts per cubic inch. In other embodiments, the power-to-volume ratio PV can be greater than or equal to 1.10 watts per cubic inch and less than or equal to 1.19 watts per cubic inch. In some embodiments, the power-to-volume ratio PV can be greater than or equal to 1.00 watts per cubic inch and less than or equal to 1.50 watts per cubic inch. In some embodiments, the power-to-volume ratio PV can be greater than or equal to 1.10 watts per cubic inch and less than or equal to 1.40 watts per cubic inch. Due to the compact arrangement of the circular saw 100 and the relatively high peak power P achieved in part due to the magnetic field weakening technology described in this invention, the circular saw 100 has a higher power-to-volume ratio PV than conventional circular saws that can operate using the saw blade 108.

[0085] exist Figure 20-24 In the illustrated configuration of the circular saw 100, i.e., with the battery pack and saw blade 108 removed, the circular saw 100 has a weight W of approximately 4.47 pounds (lbs.). In some embodiments, the weight W is less than or equal to 4.50 pounds. The circular saw 100 may have a peak power P to weight W ratio (i.e., power-to-weight ratio PW). In the illustrated embodiment, when operating with a high-capacity battery pack such as the battery pack 800 described herein, the power-to-weight ratio PW is approximately 113 watts / pound. In another embodiment, when operating with an improved high-capacity battery pack as described herein, the power-to-weight ratio PW is approximately 126 watts / pound. In other embodiments, the power-to-weight ratio PW may be greater than or equal to 113 watts / pound. In yet another embodiment, the power-to-weight ratio PW may be greater than or equal to 105 watts / pound and less than or equal to 150 watts / pound. In still another embodiment, the power-to-weight ratio PW may be greater than or equal to 110 watts / pound and less than or equal to 113 watts / pound. Due to the compact arrangement of the circular saw 100 and the relatively high peak power P achieved in part due to the magnetic field weakening technology described in this invention, the circular saw 100 has a higher power-to-weight ratio PW than conventional circular saws that can operate using the saw blade 108.

[0086] Figure 25 and 26A circular saw 100 is shown, arranged with a battery pack 800 connected thereto, and a lower saw blade guard 116 moved to a fully retracted position, in which the lower saw blade guard 116 is positioned above the workpiece contact surface 110. In this configuration, the circular saw 100 can be fully residing within the workpiece contact surface 110. Figure 26 The rectangular parallelogram 4000A shown is defined within a three-dimensional space. The rectangular parallelogram 4000A is substantially similar to the present invention regarding... Figure 20-24 The rectangular parallelogram 4000 is described, and the same features are assigned the same reference numerals. Rectangular parallelogram 4000A differs from rectangular parallelogram 4000 because the second XY plane 4025A is defined by a second vertex 4055A located on the battery pack 800 rather than on the housing assembly 106. Therefore, in this configuration, the length 4060A of the circular saw 100 is different from the previously described length 4060 (i.e., longer than length 4060). Specifically, in the illustrated embodiment, the length 4060A is 12.3125 inches (in).

[0087] exist Figure 25 and Figure 26 In the configuration shown, the rectangular parallelogram 4000A has approximately 482 cubic inches (in) 3 The volume of the rectangular parallelogram 4000A is 4005A. In some embodiments, the volume of the rectangular parallelogram 4005A may be less than or equal to 550 cubic inches to maintain a compact arrangement. In other embodiments, to maintain a compact arrangement, the volume of the rectangular parallelogram 4000A may be less than or equal to 500 cubic inches, or less than or equal to 490 cubic inches, or less than or equal to 485 cubic inches, or less than or equal to 482 cubic inches. In a further embodiment, to maintain a compact arrangement, the volume of the rectangular parallelogram 4000A may be less than or equal to 550 cubic inches and greater than or equal to 300 cubic inches. In other embodiments, the volume 4005A may be less than or equal to 500 cubic inches and greater than or equal to 350 cubic inches. In a further embodiment, the volume 4005A may be less than or equal to 49 cubic inches and greater than or equal to 460 cubic inches.

[0088] exist Figure 25-26 In the configuration of the circular saw 100 shown, i.e., with the battery pack 800 connected thereto and the saw blade 108 removed, the circular saw 100 can reside entirely in the position provided by the battery pack 800. Figure 26Within the three-dimensional space defined by the rectangular parallelogram 4000A shown. In this configuration, the circular saw 100 can have a peak power P to volume 4005A ratio (i.e., power-to-volume ratio PV2). In the illustrated embodiment, the power-to-volume ratio PV2 is approximately 1.05 watts per cubic inch. In other embodiments, the power-to-volume ratio PV2 can be greater than or equal to 1.05 watts per cubic inch. In a further embodiment, the power-to-volume ratio PV2 can be greater than or equal to 0.90 watts per cubic inch and less than or equal to 2.00 watts per cubic inch. In other embodiments, the power-to-volume ratio PV2 can be greater than or equal to 0.90 watts per cubic inch and less than or equal to 1.50 watts per cubic inch. In other embodiments, the power-to-volume ratio PV2 can be greater than or equal to 1.00 watts per cubic inch and less than or equal to 1.05 watts per cubic inch. Due to the compact arrangement of the circular saw 100 and the relatively high peak power P achieved in part due to the magnetic field weakening technology described in this invention, the circular saw 100 has a higher power-to-volume ratio PV than conventional circular saws that can operate using the saw blade 108.

[0089] Table 1 below compares the characteristics of the circular saw 100 described in this invention with three conventional prior art circular saws, which are also configured with saw blades having an operating diameter of 5-3 / 8 inches. The characteristics of the circular saw 100 listed in Table 1 include operating voltage, weight W, height 4045, length 4060, width 4075, peak power P, volume 4005, power-to-volume ratio PV, and power-to-weight ratio PW.

[0090] Table 1

[0091]

[0092] The various features of this utility model are described in the appended claims.

Claims

1. A circular saw configured to operate a saw blade having a diameter of 5-3 / 8 inches, the circular saw comprising: A base plate that defines a slot and a workpiece contact surface; A saw blade protection assembly coupled to the base plate, the saw blade protection assembly including an upper saw blade protection and a lower saw blade protection, the lower saw blade protection being movable between an extended position in which the lower saw blade protection extends through the slot and a retracted position in which the lower saw blade protection is positioned above the workpiece contact surface; Housing assembly, the housing assembly being coupled to the saw blade guard assembly; Output shaft; A saw blade clamp, the saw blade clamp being coupled to the output shaft, the saw blade clamp being configured to hold the saw blade; A brushless direct current (DC) motor, the brushless DC motor being positioned within the housing assembly and operable to rotate the output shaft; Electronic controller, the electronic controller being configured as follows: Set the conduction angle of the brushless DC motor. A pulse width modulation ("PWM") signal with a duty cycle is provided to the brushless DC motor to control the current of the brushless DC motor, and Perform a magnetic field weakening operation to modify the conduction angle of the brushless DC motor; The circular saw is configured to operate using a battery pack with a nominal rated voltage of approximately 12 volts. In response to the lower saw blade guard being stationed in the retracted position, the circular saw is fully assembled within the volume defined by the cuboid. The brushless DC motor described herein is configured to generate peak power; and The peak power to volume ratio is greater than or equal to 1.00 watts per cubic inch and less than or equal to 2.00 watts per cubic inch.

2. The circular saw as described in claim 1, characterized in that, The cuboid is defined by the following: A first XZ plane, the first XZ plane being defined by the workpiece contact surface; A second XZ plane extends parallel to the first XZ plane and is tangent to a first vertex on the circular saw, the first vertex being located at the furthest point from the first XZ plane along a direction perpendicular to the first XZ plane; A first XY plane extends perpendicularly to the first XZ plane and is tangent to the foremost edge of the base plate; A second XY plane extends parallel to the first XY plane and is tangent to a second vertex on the circular saw. The second vertex is located at the position farthest from the first XY plane along a direction perpendicular to the first XY plane. A first YZ plane extends perpendicularly to the first XZ plane and is tangent to the outermost edge of the base plate; A second YZ plane extends parallel to the first YZ plane and is tangent to a third vertex on the circular saw, the third vertex being located at the furthest point from the first YZ plane along a direction perpendicular to the first YZ plane.

3. The circular saw as described in claim 2, characterized in that, The width of the circular saw is measured perpendicularly from the first YZ plane to the second YZ plane, and the width is less than or equal to 6.00 inches (in.).

4. The circular saw as described in claim 1, characterized in that: The electronic controller is configured to determine whether the capacity of the battery pack exceeds a threshold capacity. and When the capacity of the battery pack exceeds the threshold capacity, the electronic controller performs a magnetic field weakening operation; and When the capacity of the battery pack does not exceed the threshold capacity, the electronic controller does not perform the magnetic field weakening operation.

5. The circular saw as described in claim 4, characterized in that, The threshold capacity is 3 amp-hours.

6. The circular saw as described in claim 1, characterized in that, The electronic controller is configured to increase the conduction angle of the phase of the brushless DC motor to a maximum conduction angle of 180°.

7. The circular saw as described in claim 1, characterized in that, The volume is less than or equal to 450 cubic inches (in 3 ).

8. The circular saw as described in claim 7, characterized in that, The peak power is greater than or equal to 500 watts.

9. The circular saw as described in claim 1, characterized in that, The circular saw is limited to a weight of less than or equal to 4.50 pounds (lbs.).

10. The circular saw as described in claim 1, characterized in that, The peak power to volume ratio is greater than or equal to 1.10 watts per cubic inch and less than or equal to 1.40 watts per cubic inch.

11. A circular saw configured to operate a saw blade having a diameter of 5-3 / 8 inches, the circular saw comprising: A base plate that defines a slot and a workpiece contact surface; A saw blade protection assembly coupled to the base plate, the saw blade protection assembly including an upper saw blade protection and a lower saw blade protection, the lower saw blade protection being movable between an extended position in which the lower saw blade protection extends through the slot and a retracted position in which the lower saw blade protection is positioned above the workpiece contact surface; Housing assembly, the housing assembly being coupled to the saw blade guard assembly; Output shaft; A saw blade clamp, the saw blade clamp being coupled to the output shaft, the saw blade clamp being configured to hold the saw blade; A brushless direct current (DC) motor, the brushless DC motor being positioned within the housing assembly and operable to rotate the output shaft; Electronic controller, the electronic controller being configured as follows: Set the conduction angle of the brushless DC motor. A pulse width modulation ("PWM") signal with a duty cycle is provided to the brushless DC motor to control the current of the brushless DC motor, and Perform a magnetic field weakening operation to modify the conduction angle of the brushless DC motor; The circular saw is configured to operate using a battery pack with a nominal rated voltage of approximately 12 volts. The circular saw is defined by a weight. The brushless DC motor is configured to generate peak power; and The peak power to weight ratio is greater than or equal to 105 watts per pound and less than or equal to 150 watts per pound.

12. The circular saw as described in claim 11, characterized in that: In response to the lower saw blade guard being positioned in the retracted position, the circular saw is fully assembled within the volume defined by the cuboid; and The peak power to volume ratio is greater than or equal to 1.00 watts per cubic inch and less than or equal to 2.00 watts per cubic inch.

13. The circular saw as described in claim 12, characterized in that, The cuboid is defined by the following: A first XZ plane, the first XZ plane being defined by the workpiece contact surface; A second XZ plane extends parallel to the first XZ plane and is tangent to a first vertex on the circular saw, the first vertex being located at the furthest point from the first XZ plane along a direction perpendicular to the first XZ plane; A first XY plane extends perpendicularly to the first XZ plane and is tangent to the foremost edge of the base plate; A second XY plane extends parallel to the first XY plane and is tangent to a second vertex on the circular saw. The second vertex is located at the position farthest from the first XY plane along a direction perpendicular to the first XY plane. A first YZ plane extends perpendicularly to the first XZ plane and is tangent to the outermost edge of the base plate; A second YZ plane extends parallel to the first YZ plane and is tangent to a third vertex on the circular saw, the third vertex being located at the furthest point from the first YZ plane along a direction perpendicular to the first YZ plane.

14. The circular saw as described in claim 13, characterized in that, The width of the circular saw is measured perpendicularly from the first YZ plane to the second YZ plane, and the width is less than or equal to 6.00 inches (in.).

15. The circular saw as described in claim 11, characterized in that: The electronic controller is configured to determine whether the capacity of the battery pack exceeds a threshold capacity. and When the capacity of the battery pack exceeds the threshold capacity, the electronic controller performs a magnetic field weakening operation; and When the capacity of the battery pack does not exceed the threshold capacity, the electronic controller does not perform the magnetic field weakening operation.

16. The circular saw as described in claim 15, characterized in that, The threshold capacity is 3 amp-hours.

17. The circular saw as claimed in claim 11, characterized in that, The electronic controller is configured to increase the conduction angle of the phase of the brushless DC motor to a maximum conduction angle of 180°.

18. A circular saw configured to operate a saw blade having a diameter of 5-3 / 8 inches, the circular saw comprising: A base plate that defines a slot and a workpiece contact surface; A saw blade protection assembly coupled to the base plate, the saw blade protection assembly including an upper saw blade protection and a lower saw blade protection, the lower saw blade protection being movable between an extended position in which the lower saw blade protection extends through the slot and a retracted position in which the lower saw blade protection is positioned above the workpiece contact surface; Housing assembly, the housing assembly being coupled to the saw blade guard assembly; Output shaft; A saw blade clamp, the saw blade clamp being coupled to the output shaft, the saw blade clamp being configured to hold the saw blade; A brushless direct current (DC) motor, the brushless DC motor being positioned within the housing assembly and operable to rotate the output shaft; The circular saw is configured to operate using a battery pack with a nominal rated voltage of approximately 12 volts. In response to the lower saw blade guard being stationed in the retracted position, the circular saw is fully assembled within the volume defined by the cuboid. The brushless DC motor is configured to generate peak power; The volume is less than or equal to 450 cubic inches (in 3 );as well as The peak power to volume ratio is greater than or equal to 1.00 watts per cubic inch and less than or equal to 2.00 watts per cubic inch.

19. The circular saw as described in claim 18, characterized in that, The circular saw has a defined weight, and the power-to-weight ratio of the peak power to the weight is greater than or equal to 105 watts / pound and less than or equal to 150 watts / pound.

20. The circular saw as claimed in claim 1, characterized in that, It further includes an electronic controller, the electronic controller being configured to: Set the conduction angle of the brushless DC motor. A pulse width modulation ("PWM") signal with a duty cycle is provided to the brushless DC motor to control the current of the brushless DC motor, and A magnetic field weakening operation is performed to modify the conduction angle of the brushless DC motor.

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