Electric tool and printed circuit board

Abstract

The utility model discloses an electric tool and a printed circuit board, and the electric tool comprises the printed circuit board. A printed circuit board is positioned within a housing of the power tool. The printed circuit board includes a switching network and a current sensing network. A switching network is mounted to the printed circuit board and electrically coupled to a brushless direct current ("DC") motor. A current sense resistor network is mounted to the printed circuit board and is configured to measure a current delivered to the brushless DC motor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 337,916 filed on May 3, 2022 and U.S. Provisional Patent Application No. 63 / 380,634 filed on October 24, 2022, the entire contents of each of which are incorporated herein by reference. Technical Field

[0003] Embodiments described herein relate to sensing current of a power tool. Background Art

[0004] Sensing current is an important feature of power tools, which can be used, for example, to detect a fault condition of the power tool. Conventional power tools, such as rotary hammers, are generally configured to include a housing, a printed circuit board "PCB", and a power supply assembly. However, it is now known that the space for the printed circuit board located within the housing of the power tool is limited. Therefore, there is an urgent need for a device that can sense the current of the power tool (for example, to detect a fault condition or other use) while also taking into account the space constraints of the printed circuit board of the power tool. Utility Model Content

[0005] Embodiments described herein provide a power tool, such as a rotary impact hammer.

[0006] The power tool described herein provides a power tool comprising a housing, a first variable speed input, a second variable speed input, a brushless DC ("DC") motor, a switch network, a user input, an acceleration sensor, and an electronic processor. The housing comprises a motor housing portion, a handle portion, and a battery pack interface. The first variable speed input is configured to set a maximum operating speed of the power tool. The second variable speed input is configured to control the operating speed of the power tool with the maximum operating speed of the power tool as an upper limit. The brushless DC ("DC") motor is in the motor housing portion and has a rotor and a stator. The rotor is configured to drive the motor shaft rotationally around an axis of rotation. The switch network is electrically connected to the brushless DC motor. The user input is configured to set a sensitivity level for out-of-control detection. The acceleration sensor is located on a printed circuit board. The acceleration sensor is configured to measure the acceleration of the housing of the power tool. The electronic processor is connected to the switch network and the sensor. The electronic processor is configured to control a switch network to drive a brushless DC motor based on a speed of a first variable speed input and a second variable speed input, receive one or more signals regarding acceleration of a housing of the power tool from an acceleration sensor, determine that the one or more signals exceed an acceleration threshold corresponding to a sensitivity level for loss of control detection, and control the switch network to brake the brushless DC motor in response to the one or more signals exceeding the acceleration threshold.

[0007] In some aspects, the power tool further includes a printed circuit board positioned at an angle within the housing. The acceleration sensor is located on the printed circuit board. The acceleration sensor is configured to measure acceleration of the housing of the power tool relative to at least two axes.

[0008] In some aspects, the first variable speed input is a dial.

[0009] In some aspects, the first variable speed input is configured by an external device.

[0010] In some aspects, a power tool includes at least one indicator positioned on a housing of the power tool.

[0011] In some aspects, the at least one indicator is configured to flash in a first pattern when a command for the power tool is received.

[0012] In some aspects, the at least one indicator is configured to flash in a second pattern when the sensitivity level of the loss of control detection is changed to a second level.

[0013] In some aspects, the at least one indicator is configured to flash in a third pattern when the sensitivity level of the loss of control detection is changed to a third level.

[0014] In some aspects, a sensitivity level for loss of control detection varies based on a predetermined number of activations of the second variable speed input.

[0015] The method described herein includes receiving a first variable speed input by an electronic processor. The first variable speed input is the maximum operating speed of the power tool. The method further includes receiving a second variable speed input by the electronic processor. The second variable speed input is the operating speed of the power tool, with an upper limit of the maximum operating speed of the power tool. The method further includes receiving a user input by the electronic processor. The user input is a sensitivity level for loss of control detection. The method further includes controlling a switch network of the power tool by the electronic processor to drive a brushless direct current ("DC") motor based on the operating speed of the first variable speed input and the second variable speed input. The method further includes receiving one or more signals about the acceleration of the housing of the power tool from an acceleration sensor by the electronic processor. The method further includes determining by the electronic processor that one or more signals exceed an acceleration threshold corresponding to the sensitivity level for loss of control detection. The method further includes controlling the switch network to brake the brushless DC motor by the electronic processor in response to the one or more signals exceeding the acceleration threshold.

[0016] In some aspects, the method includes causing, by an electronic processor, an indicator of a housing of the power tool to flash in a first pattern when a command for the power tool is received.

[0017] In some aspects, the indicator of the housing of the power tool is caused by the electronic processor to flash according to a third pattern when the sensitivity level of the runaway detection is changed to a third level.

[0018] In some aspects, a sensitivity level for loss of control detection is modified by the electronic processor based on a predetermined number of activations of the second variable speed input.

[0019] In some aspects, the first variable speed input is received by the electronic processor from an external device.

[0020] Embodiments described herein provide a power tool comprising a housing, a first variable speed input, a second variable speed input, a brushless DC ("DC") motor, a switch network, a printed circuit board, a user input, an acceleration sensor, and an electronic processor. The housing comprises a motor housing portion, a handle portion, and a battery pack interface. The first variable speed input is configured to set a maximum operating speed of the power tool. The second variable speed input is configured to control the operating speed of the power tool with the maximum operating speed of the power tool as an upper limit. The brushless DC ("DC") motor is within the motor housing portion and has a rotor and a stator. The rotor is configured to drive the motor shaft rotationally around a rotation axis. The switch network is electrically coupled to the brushless DC motor. The printed circuit board is angularly positioned within the housing. The user input is configured to set a sensitivity level for runaway detection. The acceleration sensor is located on the printed circuit board. The acceleration sensor is configured to measure the acceleration of the housing of the power tool relative to at least two axes. The electronic processor is connected to the switch network and the sensor. The electronic processor is configured to control a switch network to drive a brushless DC motor based on a speed of a first variable speed input and a second variable speed input, receive one or more signals regarding acceleration of a housing of the power tool from an acceleration sensor, determine that the one or more signals exceed an acceleration threshold corresponding to a sensitivity level for loss of control detection, and control the switch network to brake the brushless DC motor in response to the one or more signals exceeding the acceleration threshold.

[0021] Embodiments described herein provide a power tool (e.g., a rotary hammer) configured to detect a runaway event. The power tool includes a housing having a motor housing portion, a handle portion, a trigger, and a battery pack interface. The power tool further includes a brushless direct current ("DC") motor within the motor housing portion and having a rotor and a stator. The rotor is configured to drive the motor shaft rotationally about an axis of rotation. The power tool further includes a switch network electrically connected to the brushless DC motor. The power tool further includes an angled printed circuit board ("PCB") positioned at an angle within the power tool. The power tool further includes a receiver and a sensor, the receiver being configured to receive a set sensitivity level for runaway detection, the sensor being configured on the printed circuit board and configured to measure acceleration of the housing relative to at least two axes. The power tool includes an electronic processor coupled to a switch network and a sensor and configured to achieve loss of control of the power tool, wherein the electronic processor is configured to control the switch network to drive a brushless DC motor at a speed equal to or less than a maximum operating speed set by a variable speed input, receive acceleration measurements of a housing of the power tool from the sensor, and determine at least one predetermined threshold value corresponding to a set loss of control sensitivity level. The electronic processor is further configured to determine that a plurality of acceleration measurements of the housing of the power tool exceed at least one predetermined acceleration threshold value corresponding to the set loss of control sensitivity level. The electronic processor controls the switch network to brake the brushless DC motor in response to determining that the plurality of acceleration measurements exceed the threshold value.

[0022] Embodiments described herein provide a power tool comprising a housing having a motor housing portion, a handle portion, and a battery pack interface. The power tool further comprises a brushless direct current ("DC") motor within the motor housing portion and having a rotor and a stator. The rotor is configured to drive the motor shaft rotationally about an axis of rotation. The power tool further comprises a switch network electrically connected to the brushless DC motor. The power tool further comprises a user input function to set a loss of control sensitivity level. The power tool further comprises an electronic processor. The user selects a loss of control sensitivity level, and the electronic processor determines a set of predetermined thresholds corresponding to the set sensitivity level. The electronic processor then detects a loss of control event and stops the motor operation.

[0023] Embodiments described herein provide a power tool comprising a housing having a motor housing portion, a handle portion, and a battery pack interface. The power tool further comprises a brushless direct current ("DC") motor within the motor housing portion and having a rotor and a stator. The rotor is configured to drive the motor shaft rotationally around the axis of rotation. The power tool further comprises a switch network electrically connected to the brushless DC motor. The power tool further comprises an out-of-control detection feature. Out-of-control sensitivity detection is set by a user. The out-of-control sensitivity level corresponds to a plurality of predetermined thresholds. The power tool further comprises at least one indicator located on the power tool housing. The indicator is configured to flash in a first mode, for example, when a user sends a command for the power tool. The indicator is further configured to flash in a second mode when the sensitivity level of out-of-control detection changes to a different sensitivity level. The indicator is also configured to flash in a third mode when the sensitivity level of out-of-control detection changes to the original sensitivity level.

[0024] Embodiments described herein provide a power tool comprising a housing having a motor housing portion, a handle portion, and a battery pack interface. The power tool further comprises a brushless direct current ("DC") motor within the motor housing portion and having a rotor and a stator. The rotor is configured to drive the motor shaft rotationally around an axis of rotation. The power tool further comprises a switch network electrically connected to the brushless DC motor. The power tool further comprises a first variable speed input. The first variable speed input is configured to select a maximum operating speed of the power tool. The power tool further comprises a second variable speed input, which controls the operating speed of the power tool. Between the first variable speed input and the second variable speed input, the power tool operates under a selected speed condition.

[0025] Embodiments described herein provide an electric tool comprising a housing, a brushless direct current ("DC") motor, and a current sensing resistor network. The brushless direct current ("DC") motor is within a motor housing portion and has a rotor and a stator. The rotor is configured to drive a motor shaft rotationally about an axis of rotation. The current sensing resistor network is mounted to a printed circuit board. The current sensing resistor network includes a first current sensing resistor, a second current sensing resistor, and a third current sensing resistor. The second current sensing resistor forms an angle of approximately 45 degrees relative to the first current sensing resistor and the second current sensing resistor. The current sensing resistor network is configured to measure the current transmitted to the brushless DC motor.

[0026] Embodiments described herein provide a method for operating a power tool. The method includes receiving a first variable speed input by an electronic processor. The first variable speed input is a maximum operating speed of the power tool. The method further includes receiving a second variable speed input by the electronic processor. The second variable speed input is an operating speed of the power tool, with an upper limit of the maximum operating speed of the power tool. The method further includes receiving a user input by the electronic processor. The user input is a sensitivity level for loss of control detection. The method further includes controlling a switch network of the power tool by the electronic processor to drive a brushless direct current ("DC") motor based on the operating speed of the first variable speed input and the second variable speed input. The method further includes receiving one or more signals about the acceleration of a housing of the power tool from an acceleration sensor by the electronic processor. The acceleration sensor is located on a printed circuit board and measures the acceleration of the housing of the power tool relative to at least two axes. The printed circuit board is angularly positioned within the housing. The method further includes determining by the electronic processor that one or more signals exceed an acceleration threshold corresponding to the sensitivity level for loss of control detection. The method further includes controlling the switch network to brake the brushless DC motor by the electronic processor in response to the one or more signals exceeding the acceleration threshold.

[0027] Embodiments described herein provide a method for operating a power tool. The method includes receiving a first variable speed input by an electronic processor. The first variable speed input is a maximum operating speed of the power tool. The method further includes receiving a second variable speed input by the electronic processor. The second variable speed input is an operating speed of the power tool, with an upper limit of the maximum operating speed of the power tool. The method further includes receiving a user input by the electronic processor. The user input is a sensitivity level for loss of control detection. The method further includes controlling a switch network of the power tool by the electronic processor to drive a brushless direct current ("DC") motor based on the operating speed of the first variable speed input and the second variable speed input. The method further includes receiving one or more signals about the acceleration of a housing of the power tool from an acceleration sensor by the electronic processor. The acceleration sensor is located on a printed circuit board and measures the acceleration of the housing of the power tool relative to at least two axes. The printed circuit board is angularly positioned within the housing. The method further includes determining by the electronic processor that one or more signals exceed an acceleration threshold corresponding to the sensitivity level for loss of control detection. The method further includes controlling the switch network to brake the brushless DC motor by the electronic processor in response to the one or more signals exceeding the acceleration threshold. The method further includes causing, by the electronic processor, an indicator of the housing of the power tool to flash in a first pattern when a command for the power tool is received. The method further includes causing, by the electronic processor, an indicator of the housing of the power tool to flash according to a second pattern when the sensitivity level of out-of-control detection changes to a second level. The method further includes causing, by the electronic processor, an indicator of the housing of the power tool to flash according to a third pattern when the sensitivity level of out-of-control detection changes to a third level.

[0028] The power tool described herein includes a printed circuit board positioned within a housing of the power tool. The printed circuit board includes a switch network mounted to the printed circuit board. The switch network is electrically coupled to a brushless direct current ("DC") motor. The printed circuit board includes a current sensing resistor network mounted to the printed circuit board. The current sensing resistor network is configured to measure current delivered to the brushless DC motor.

[0029] In some aspects, the current sensing resistor network is positioned on the printed circuit board proximate to the switch network.

[0030] In some aspects, the current sensing resistor network includes a first current sensing resistor, a second current sensing resistor, and a third current sensing resistor. The second current sensing resistor is positioned equidistantly between the first current sensing resistor and the third current sensing resistor.

[0031] In some aspects, the second current sensing resistor is positioned to form an angle of approximately 45 degrees relative to the first current sensing resistor and the third current sensing resistor.

[0032] In some aspects, the switch network includes a first field effect transistor ("FET") associated with a first phase of a brushless DC motor, a second FET associated with a second phase of the brushless DC motor, and a third FET associated with a third phase of the brushless DC motor.

[0033] In some aspects, the first FET, the second FET, and the third FET are positioned to form a line proximate to the current sensing resistor network.

[0034] In some aspects, the first current sensing resistor is positioned at an angle of approximately 135 degrees relative to the line formed near the current sensing resistor network, the second current sensing resistor is positioned at an angle of approximately 90 degrees relative to the line formed near the current sensing resistor network, and the third current sensing resistor is positioned at an angle of approximately 45 degrees relative to the line formed near the current sensing resistor network.

[0035] A printed circuit board described herein includes a switch network mounted to the printed circuit board and a current sensing resistor network mounted to the printed circuit board, the current sensing resistor network being configured for measuring current delivered to a brushless direct current ("DC") motor based on the switch network.

[0036] In some aspects, the current sensing resistor network includes a first current sensing resistor, a second current sensing resistor, and a third current sensing resistor, and wherein the second current sensing resistor is positioned equidistantly between the first current sensing resistor and the third current sensing resistor.

[0037] In some aspects, the second current sensing resistor is positioned to form an angle of approximately 45 degrees relative to the first current sensing resistor and the third current sensing resistor.

[0038] In some aspects, the switch network includes a first field effect transistor ("FET") associated with a first phase of a brushless DC motor, a second FET associated with a second phase of the brushless DC motor, and a third FET associated with a third phase of the brushless DC motor.

[0039] In some aspects, the first FET, the second FET, and the third FET are positioned to form a line proximate to the current sensing resistor network.

[0040] In some aspects, the first current sensing resistor is positioned at an angle of approximately 135 degrees relative to the line formed near the current sensing resistor network, the second current sensing resistor is positioned at an angle of approximately 90 degrees relative to the line formed near the current sensing resistor network, and the third current sensing resistor is positioned at an angle of approximately 45 degrees relative to the line formed near the current sensing resistor network.

[0041] In some aspects, the first FET is positioned at an angle of approximately 135 degrees relative to the line formed near the current sensing resistor network, the second FET is positioned at an angle of approximately 90 degrees relative to the line formed near the current sensing resistor network, and the third FET is positioned at an angle of approximately 45 degrees relative to the line formed near the current sensing resistor network.

[0042] Before explaining any embodiment in detail, it should be understood that the embodiment does not limit its application to the configuration details and component arrangements set forth in the following description or shown in the accompanying drawings. The embodiments can be practiced or implemented in a variety of different ways. It should also be understood that the words and terms used herein are for illustrative purposes and should not be considered restrictive. The use of "including", "comprising" or "having" and variations thereof is intended to cover the items listed below and their equivalents, as well as additional items. Unless otherwise specified or limited, the terms "mount", "connect", "support" and "couple", and variations thereof are widely used and cover both direct mounting, connection, support and coupling and indirect mounting, connection, support and coupling.

[0043] In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules, which, for the purpose of discussion, may be shown and described as if most components are implemented only in hardware. However, those of ordinary skill in the art will recognize, based on reading this detailed description, that in at least one embodiment, electronic-based aspects may be implemented in software (e.g., stored on a non-transient computer-readable medium) that may be executed by one or more processing units (e.g., microprocessors and / or application-specific integrated circuits ("ASICs")). Thus, it should be noted that embodiments may be implemented using a plurality of hardware- and software-based devices and a plurality of different structural components. For example, the "server," "computing device," "controller," "processor," etc. 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 a plurality of different connectors (e.g., a system bus) connecting components.

[0044] Relative terms used in conjunction with quantities or conditions, such as "about", "approximately", "substantially", etc., will be understood by those of ordinary skill in the art to include the values ​​described and have the meaning dictated by the context (e.g., the terms include at least the degree of error associated with the precision of the measurements, the tolerance associated with the specific values ​​[e.g., manufacturing, assembly, use, etc.], etc.). Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the expression "about 2 to about 4" also discloses a range of "2 to 4". Relative terms can refer to percentages (e.g., 1%, 5%, 10%, or more) of the indicated values ​​plus or minus.

[0045] It should be understood that although some drawings show the hardware and software in a particular device, these depictions are for illustrative purposes only. The function described herein as being performed by a component can be performed in a distributed manner by multiple components. Likewise, the function performed by multiple components can be merged and performed by a single component. In some embodiments, the components shown can be combined or divided into separate software, firmware and / or hardware. For example, logic and processing can be distributed between multiple electronic processors, rather than being located in a single electronic processor and performed by it. Regardless of how hardware components and software components are combined or divided, hardware components and software components can be located on the same computing device or can be distributed between different computing devices connected by one or more networks or other suitable communication links. Similarly, components described as performing a specific function can also perform additional functions not described herein. For example, a device or structure that is "configured" in a certain way is configured at least in this way, but can also be configured in a way that is not explicitly listed.

[0046] Other aspects of the embodiments will become apparent by consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 An embodiment of a power tool is shown.

[0048] Figure 2 Shown Figure 1 An embodiment of a communication network for power tools.

[0049] Figure 3 Shown Figure 1 An embodiment of a controller for an electric tool.

[0050] Figure 4 Shown Figure 1 Embodiment of a switching network of a power tool.

[0051] Figure 5 Shown Figure 1 Embodiment of an angled printed circuit board for a power tool.

[0052] Fig. 6A and Figure 6B A runaway event movement is shown according to some embodiments.

[0053] Figure 7 A method of detecting a loss of control event according to some embodiments is presented.

[0054] Figure 8 A method of selecting a runaway sensitivity level according to some embodiments is presented.

[0055] Fig. 9 Methods for selecting and indicating runaway sensitivity levels are demonstrated.

[0056] Fig.10 The configuration according to some embodiments is shown Figure 1 Method of maximum speed of power tools.

[0057] Fig.11A Demonstrating some embodiments Figure 1 Configuration of components of the printed circuit board of an electric tool.

[0058] Fig. 11B Demonstrating some embodiments Figure 1 A linear center-mount current sense resistor configuration for components of a power tool's printed circuit board.

[0059] Fig. 11C Demonstrating some embodiments Figure 1 A center mounted current sensing resistor configuration of a component of a power tool's printed circuit board. DETAILED DESCRIPTION

[0060] Figure 1A power tool 100 (e.g., a rotary hammer) is shown that includes a brushless direct current ("DC") electric motor 105 and an output housing 140. The output housing 140 includes a gear train 140a that receives torque from the motor 105 to rotate a spindle 145 and a reciprocating mechanism 140b that is operable to apply an axial impact to an output shaft 150 (e.g., a drill bit) driven by the spindle 145. The motor 105 receives power from a power source (e.g., a battery pack 135). The battery pack 135 can include any of a number of different nominal voltages (e.g., 12V, 18V, etc.) and can be configured to have any of a number of different chemistries (e.g., lithium ion, nickel cadmium, pouch cells, etc.). In some embodiments, the battery pack 135 is removably coupled to the power tool housing 160. Alternatively, the motor 105 can be powered by a remote power source (e.g., an electrical outlet) via a power cord. The power tool 100 further includes a first variable speed input or trigger 165 for controlling the motor 105. Once the trigger 165 is depressed, the trigger 165 drives the motor 105. In some embodiments, the deeper the trigger 165 is depressed, the faster the motor 105 rotates, thereby increasing the rotation speed of the spindle 145.

[0061] The power tool 100 includes a mode selection member 175 that an operator can rotate to switch between a plurality of modes. For example, the mode selection member 175 can be used to select a hammer drill mode, a drill mode, or a hammer-only mode.

[0062] The power tool 100 also includes a printed circuit board ("PCB") 115 and an onboard power source (e.g., a battery pack 135) positioned within a PCB housing 110 (e.g., a heat sink). A bottom wall 125 encloses a plurality of electrical components and allows the PCB 115 to be secured at an angle within a power tool housing 160. The power tool further includes a second variable speed input (e.g., a dial) 170. The dial 170 (described in further detail below) is operable to set the maximum speed of the power tool 100. Wires W electrically connect the motor 105, the PCB 115, the dial 170, and the battery pack 135. The interior 120 of the PCB housing 110 includes a plurality of switches, such as field effect transistors ("FETs") 130, mounted on a first surface 115a of the PCB 115 and operable to function as an inverter bridge circuit to direct current from the battery pack 135 to the motor 105. During use of the power tool 100, the FETs 130 are switched rapidly and sequentially (which generates heat) to transfer power from the battery pack 135 to the motor 105. The PCB 115 includes an opposing second surface 115b on which other electrical components are mounted.

[0063] Figure 2A communication system 200 of a power tool 100 is shown. The communication system 200 includes a power tool 100 and an external device 206. Each power tool 100 and the power tool battery pack 135 and the external device 206 can communicate wirelessly when they are within the communication range of each other. Each power tool 100 can transmit power tool status, power tool operation statistics, power tool identification, stored power tool usage information, power tool maintenance data, etc. Therefore, using the external device 206, the user can access the stored power tool usage or power tool maintenance data. Using this tool data, the user can determine the way the power tool 100 has been used, whether maintenance is recommended or has been performed in the past, and identify faulty parts or other causes of certain performance problems. The external device 206 is also configured to transmit data to the power tool 100 for power tool configuration, firmware update, or sending commands (e.g., turning on the work light, setting the maximum speed, setting the out-of-control sensitivity, etc.). The external device 206 also allows the user to set operating parameters, safety parameters, select tool modes, etc. for the power tool 100.

[0064] The external device 206 can be, for example, a smart phone (as shown), a laptop computer, a tablet computer, a personal digital assistant ("PDA"), or another electronic device capable of wirelessly communicating with the power tool 100 and providing a user interface. The external device 206 provides a user interface and allows a user to access and interact with the power tool 100. The external device 206 is configured to receive user input to determine operating parameters, enable or disable features, etc. The user interface of the external device 206 provides an easy-to-use interface for the user to control and customize the operation of the power tool 100.

[0065] The external device 206 includes a communication interface that is compatible with the wireless communication interface of the power tool 100. The communication interface of the external device 206 may include a wireless communication controller (e.g., Module) or similar components. Therefore, the external device 206 allows the user to access data related to the power tool 100 and provides a user interface so that the user can interact with the electronic processor of the power tool 100.

[0066] In addition, if Figure 2As shown in , the external device 206 can also share information obtained from the power tool 100 with a remote server 212 connected via a network 214. The remote server 212 can be used to store data obtained from the external device 206, provide additional functions and services to the user, or a combination thereof. In one embodiment, storing information on the remote server 212 allows the user to access the information from multiple different locations. In another embodiment, the remote server 212 can collect information about their power tools from various users and provide statistical information or statistical metrics to the user based on the information obtained from different power tools. For example, the remote server 212 can provide statistical data on the experience efficiency of the power tool 100, the typical use of the power tool 100, and other relevant characteristics and / or metrics of the power tool 100. The network 214 may include various networking elements (routers, hubs, switches, cellular towers, wired connections, wireless connections, etc.) for connecting to, for example, the Internet, a cellular data network, a local area network, or a combination thereof. In some embodiments, the power tool 100 may be configured to communicate directly with the remote server 212 via an additional wireless interface or the same wireless interface that the power tool 100 uses to communicate with the external device 206 .

[0067] In some embodiments, the power tool 100 and the power tool battery pack 135 can communicate wirelessly with each other via corresponding wireless transceivers within each device. For example, the power tool battery pack 135a can transmit battery characteristics to the power tool 100 (e.g., battery pack identification, battery pack type, battery pack weight, current output capacity, etc.). Such communication can occur when the battery pack 135 is connected to the power tool 100. Additionally or alternatively, when the battery pack 135 is connected to the power tool 100, the battery pack 135 and the power tool 100 can communicate with each other using a communication terminal.

[0068] Figure 3 A control system for a power tool 100 is shown. The control system includes a controller 300. The controller 300 is electrically and / or communicatively connected to various modules or components of the power tool 100. For example, the controller 300 shown is electrically connected to the motor 105, the battery pack interface 310, the trigger switch 315 (connected to the trigger 165), one or more sensors or sensing circuits 325, one or more indicators 330, a user input module 335, a power input module 340, a communication module 345 (e.g., for communicating with an external device 206), and a switch module 350 (e.g., including multiple switch FETs 130). The controller 300 includes a combination of hardware and software that are particularly operable to control the operation of the power tool 100, monitor the operation of the power tool 100, activate one or more indicators 330 (e.g., LEDs), etc.

[0069] The controller 300 includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 300 and / or the power tool 100. For example, the controller 300 includes, among other things, a processing unit 355 (e.g., a microprocessor, a microcontroller, an electronic processor, an electronic controller, or another suitable programmable device), a memory 360, an input unit 365, and an output unit 370. The processing unit 355 includes, among other things, a control unit 375, an arithmetic logic unit ("ALU") 380, and a plurality of registers 385, and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 355, the memory 360, the input unit 365, and the output unit 370, as well as the various modules or circuits connected to the controller 300, are connected via one or more control buses and / or data buses (e.g., a common bus 390). For illustrative purposes, in Figure 3 A control bus and / or a data bus are generally shown in FIG. In view of the present invention described herein, those skilled in the art will appreciate the use of one or more control buses and / or data buses for interconnection and communication between various modules, circuits and components.

[0070] The memory 360 is a non-transitory computer-readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area may include a combination of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card or other suitable magnetic storage device, optical storage device, physical storage device or electronic storage device. The processing unit 355 is connected to the memory 360 and executes software instructions, which can be stored in the RAM of the memory 360 (e.g., during execution), the ROM of the memory 360 (e.g., on a generally permanent basis) or another non-transitory computer-readable medium such as another memory or disk. The software included in the embodiment of the power tool 100 can be stored in the memory 360 of the controller 300. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules and other executable instructions. The controller 300 is configured to retrieve from the memory 360 and also execute instructions related to the control process and method described herein. In other configurations, the controller 300 includes additional components, fewer components or different components.

[0071] The battery pack interface 310 includes a combination of mechanical components (e.g., tracks, grooves, latches, etc.) and electrical components (e.g., one or more terminals) that are configured and operable to interface (e.g., mechanically, electrically, and communicatively connect) the power tool 100 with a battery pack (e.g., battery pack 135). For example, power provided to the power tool 100 by the battery pack 135 is provided to the power input module 340 via the battery pack interface 310. The power input module 340 includes a combination of active and passive components to regulate or control the power received from the battery pack 135 before providing the power to the controller 300. The battery pack interface 310 also supplies power to the switch module 350 to supply power to the motor 105. The battery pack interface 310 also includes, for example, a communication line 395 for providing a communication line or link between the controller 300 and the battery pack 135.

[0072] The indicator 330 includes, for example, one or more light emitting diodes ("LEDs"). The indicator 330 can be configured to display the condition of the power tool 100 or information related to the power tool. For example, the indicator 330 is configured to indicate the measured electrical characteristics of the power tool 100, the status of the power tool 100, the loss of control sensitivity level, the operating mode of the power tool 100, etc. The user input module 335 is operably connected to the controller 300 to, for example, select a forward operating mode or a reverse operating mode, select a torque and / or speed setting of the power tool 100 (e.g., using a torque and / or speed switch), etc. In some embodiments, the user input module 335 includes a combination of digital and analog input or output devices required to achieve the desired operating level of the power tool 100, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc.

[0073] The controller 300 is configured to determine whether a fault condition exists with the power tool 100 and to generate one or more control signals associated with the fault condition. For example, the sensing circuit 325 includes one or more current sensors, one or more speed sensors, one or more Hall effect sensors, one or more temperature sensors, one or more acceleration sensors, a gyroscope, an inertial measurement unit ("IMU"), etc. The controller 300 calculates or includes in the memory 360 predetermined operating thresholds and limits for the operation of the power tool 100. For example, when the controller 300 detects or predicts a potential thermal failure (e.g., thermal failure of a FET, motor 105, etc.), power to the motor 105 may be limited or interrupted until the likelihood of thermal failure is reduced. Similarly, if the controller 300 determines that the power tool 100 is experiencing a runaway event, the controller may brake the motor 105 to help mitigate the runaway event. If the controller 300 detects one or more such fault conditions of the power tool 100 or determines that the fault condition of the power tool 100 no longer exists, the controller 300 is configured to provide information and / or control signals to another component of the battery pack 135 (e.g., the battery pack interface 310, the indicator 330, etc.).

[0074] Figure 4A control diagram 400 of the FET switch module 350 is shown. The FET switch module 350 includes a plurality of high-side power switch elements 402 and a plurality of low-side power switch elements 404. The controller 300 provides control signals to control the high-side FETs 402 and the low-side FETs 404 to drive the motor 105 based on motor feedback information and user control as described above. For example, in response to detecting a pull of the trigger 165, the controller 300 provides control signals to selectively (e.g., sequentially, in pairs) enable and disable the FETs 402 and 404 so that power from a power source (e.g., the battery pack 135) is selectively applied to the stator coils of the motor 105 to cause rotation of the rotor. More specifically, to drive the motor 105, the controller 300 enables a first high-side FET 402 and a first low-side FET 404 pair (e.g., by providing a voltage at the gate terminals of the FETs) for a first time period. In response to determining that the rotor of the motor 105 has rotated based on the pulses from the sensing circuit 325, the controller 300 disables the first FET pair and enables the second high-side FET 402 and the second low-side FET 404. In response to determining that the rotor of the motor 105 has rotated based on the pulses from the sensing circuit 325, the controller 300 disables the second FET pair and enables the third high-side FET 402 and the third low-side FET 404. This sequence of cyclically enabling the pairs of high-side FETs 402 and low-side FETs 404 is repeated to drive the motor 105. Further, in some embodiments, the control signal includes a pulse width modulation (“PWM”) signal having a duty cycle that is set in proportion to the amount of trigger pull of the trigger 165, thereby controlling the speed or torque of the motor 105.

[0075] Figure 5 A side view 500 of the PCB 115 is shown. The PCB 115 is positioned within the power tool 100 at an inclined angle within the power tool housing 160 structure of the power tool 100. Each side of the PCB housing 110 (or heat sink) contacts, for example, a wall of the power tool housing 160. In some embodiments, each side of the PCB housing 110 contacts the wall of the power tool housing 160 at a different contact point, thereby securing the PCB 115 at an inclined angle relative to the normal orientation of the power tool 100. This ensures that the PCB 115 is tilted relative to the normal operating plane of the power tool 100 (e.g., Figure 5 For example, it is suggested that the normal operating plane is along the X-axis to move the power tool 100 horizontally (e.g., so that the output shaft 150 is perpendicular to the work surface). The normal operating plane also includes a Y-axis to represent the vertical movement of the power tool 100.

[0076] PCB 115 includes a sensor 505 (e.g., a gyroscope that measures angular velocity or rate, one or more acceleration sensors, an inertial measurement unit ("IMU"), etc.) coupled to the first surface 115a. Because the PCB 115 is inserted into the tool at such an angle, the sensor will also have a detection axis that is angled relative to the normal operating plane. In some embodiments, the sensor 505 is a gyroscope. The sensor 505 is configured to generate an output signal related to the movement of the power tool 100. In a preferred embodiment, the sensor 505 is configured to generate a plurality of output signals, including an X-component output signal and a Y-component output signal. By tilting the sensor, the PCB 115 is able to determine a composite vector 510 generated by the X-component and the Y-component. By using the composite vector, the power tool 100 is able to detect a loss of control of the power tool 100 relative to at least two axes, rather than just the vertical or horizontal (relative to the normal operating plane) values ​​from the non-angled PCB.

[0077] Fig. 6A and Figure 6B Movement of the power tool 100 that triggers loss of control detection in some embodiments is shown. Fig. 6A , the power tool 100 is shown in a side view to demonstrate movement along the X-axis. A sensor 505 is located on the PCB 115 to detect a first value along the X-axis. In some embodiments, the first value is an acceleration value (e.g., measured using an accelerometer). In some embodiments, the first value is an angular velocity value (e.g., measured using a gyroscope). The power tool 100 can also be shown as moving on the Y-axis. A sensor is located on the PCB 115 to detect a second value along the Y-axis. In some embodiments, the second value is an acceleration value (e.g., measured using an accelerometer). In some embodiments, the second value is an angular velocity value (e.g., measured using a gyroscope). Given these two component values, the controller 300 can then determine a resultant vector. Since the PCB 115 is tilted relative to the normal operating plane, the PCB 115 can determine whether the resultant vector exceeds a predetermined threshold, and if so, a loss of control is detected. In addition, in Figure 6B , the power tool 100 is shown from a rear view angle. The power tool 100 can rotate from one side to the other about the output shaft (for example, in the event of a kickback condition). This rotational movement can be caused by a normal operating measure (for example, the user rotating the tool), or the rotational movement may be the result of a loss of control (for example, kickback). If the sensor 505 detects that the movement of the power tool 100 exceeds a predetermined threshold of rotational movement based on the resultant vector, the power tool 100 will consider this action to be a loss of control and, in some embodiments, brake the motor 105. By using two axis detection, loss of control can be detected from movement in the X direction only, movement in the Y direction only, or a combination of the X and Y directions, as long as the resultant vector reaches or exceeds the predetermined threshold.

[0078] Figure 7 A method 700 of detecting a loss of control event of the power tool 100 is shown. For example, the power tool includes a sensor 505 located on the PCB 115 that monitors the movement of the power tool 100. The PCB 115 can detect the loss of control via an output signal of the sensor 505.

[0079] The sensor 505 does this by detecting a first value on a first axis (step 705). In some embodiments, the first value is an acceleration value (e.g., measured using an accelerometer). In some embodiments, the first value is an angular velocity value (e.g., measured using a gyroscope). In some embodiments, the first axis is Figure 5 The sensor then detects a second value on a second axis (step 710). In some embodiments, the second value is an acceleration value (e.g., measured using an accelerometer). In some embodiments, the second value is an angular velocity value (e.g., measured using a gyroscope). In some embodiments, the second axis is Figure 5 . Using the first value on the first axis and the second value on the second axis, the controller 300 determines a resultant vector value (step 715). The controller 300 then compares the determined resultant vector value with a predetermined threshold (step 720). If the vector value does not exceed the predetermined threshold, the sensor will return to detecting the value on each axis. If the vector value exceeds the predetermined threshold, the controller 300 will determine that a loss of control event has occurred. The controller 300 will then use the FET 130 to stop the motor 105 (step 725) and stop any further rotation of the power tool 100.

[0080] Figure 8A method 800 for detecting that an out-of-control event has occurred for a power tool 100 is shown. For method 800, a user can select whether an out-of-control detection feature is available during use of the power tool 100. In some embodiments, a user input module 335 is used to enable or disable out-of-control detection. In some embodiments, an external device 206 is used to enable or disable out-of-control detection. If the user turns on the out-of-control feature (step 805), the user will be able to select a specific sensitivity level that will activate the out-of-control detection feature within the power tool 100 (step 810). For example, if the workpiece is particularly hard, the power tool 100 may be prone to excessive movement (e.g., rotation) of the power tool 100 without the user losing control of the power tool 100. In this case, a higher out-of-control threshold can be expected. Once the user selects an out-of-control sensitivity level, the controller 300 will determine a predetermined out-of-control threshold for the selected sensitivity level (step 815). For example, if the user selects a high sensitivity level, the predetermined threshold will be higher than when the user selects a low sensitivity level (e.g., a larger value of the composite vector of the sensor 505).

[0081] Once the selection of the sensitivity level has occurred, the sensor 505 will continue to monitor the first value on the first axis and the second value on the second axis. Figure 7 In the method 700 described, the controller 300 will determine the resultant vector and then compare the resultant vector value to a predetermined threshold. The predetermined threshold may vary depending on the sensitivity level selected, but if the resultant vector value exceeds the predetermined threshold, the controller 300 will stop the motor from operating (step 825). In some embodiments, the controller 300 will brake the motor 105.

[0082] Fig. 9 A method 800 for setting an out-of-control sensitivity level for a power tool 100 is shown. Once the power tool 100 begins operating (step 905), the user is able to send interactive commands to the power tool 100 (step 910). In some embodiments, the user uses an external device 206 to set the sensitivity level of the power tool 100. For example, there are two sensitivity modes: a default sensitivity mode and a low sensitivity mode. The default sensitivity mode includes an average predetermined threshold for the operation of the power tool 100 under normal and average operating conditions. The low sensitivity mode includes a lower predetermined threshold for the operation of the power tool 100 under specific conditions. Selecting the low sensitivity mode may be a result of working on a specific type of workpiece. In other embodiments, additional sensitivity levels (e.g., a high sensitivity level) may be included.

[0083] In another embodiment, the user pulls the trigger 165 a predetermined number of times (e.g., five times) in succession during operation of the power tool 100. The series of inputs or trigger activations causes the power tool to adjust the fail-safe sensitivity from a first level to a second level. The power tool receives the user input (e.g., from the external device 206 or from the trigger pull) and sets the sensitivity level of the power tool 100 (step 915). In response to receiving the command to set the sensitivity level, at least one indicator (e.g., an LED located on the power tool housing 160) flashes in a first light pattern (e.g., the indicator flashes a light once) (step 920).

[0084] At any point in the operation of the power tool 100, the user can change the sensitivity level without interrupting operation. The need to change the sensitivity level can be the result of, for example, a change in the composition of the workpiece. If the user wishes to change the sensitivity level during operation of the power tool 100 (step 925), the user can communicate with the power tool to change the sensitivity level to high sensitivity or low sensitivity. In one embodiment, the user changes the sensitivity level via the external device 206. In another embodiment, the user changes the sensitivity level by pulling the trigger 165 multiple times in succession. Once the power tool 100 receives the command, at least one indicator flashes in a second mode (e.g., flashes twice) to communicate that the power tool 100 has entered a different sensitivity mode (step 930).

[0085] The user can select a third sensitivity level or return to the original sensitivity level at any point in the operation. The user communicates with the power tool 100 again to change the sensitivity level to, for example, a high sensitivity level or a low sensitivity level. In one embodiment, the user changes the sensitivity level via the external device 206. In another embodiment, the user changes the sensitivity level by pulling the trigger 165 multiple times in succession. Once the power tool 100 receives this command (step 935), at least one indicator flashes in a third mode (e.g., flashes four times), thereby conveying that the power tool 100 is entering a different sensitivity mode (step 940).

[0086] Fig.10A method 1000 of controlling the output of the power tool 100 of the power tool 100 is shown. In some embodiments, the user is able to select the maximum operating speed of the power tool 100. This allows the power tool 100 to operate more controlled to ensure that the spindle 145 will not exceed the appropriate rotational speed depending on the user's needs. The user first begins to select the maximum operating speed via a first variable speed input (e.g., a dial 170) (step 1005). In some embodiments, the user can select the maximum operating speed through an external device 206 (e.g., a smart phone). Additionally or alternatively, the power tool 100 includes a dial 170 located on the power tool 100. The dial 170 is configured so that the maximum speed output is set by turning the dial 170 to the desired maximum output (e.g., corresponding to a number between 1 and 10). The user can then control the operating speed of the power tool 100 via a second variable speed input (e.g., a variable speed trigger 320) (step 1010). In some embodiments, the second variable speed input includes a variable speed trigger 320. The variable speed trigger 320 allows the user to adjust the speed based on the position of the variable speed trigger 320. For example, the rotational speed of the output shaft 150 increases as the variable speed trigger 320 is pressed toward the inward position, and the rotational speed of the output shaft 150 decreases as the variable speed trigger is released toward the outward position. Once the maximum operating speed is set and the user is controlling the operating speed via the second variable speed input, the user is able to operate the power tool 100 at the selected speed condition (step 1015). For example, the target maximum speed of the power tool 100 is achieved when the variable speed trigger is moved to the maximum inward position, but the target maximum speed is not exceeded. This allows controlled operational use and optimal operating performance.

[0087] Fig.11AA configuration of components of a PCB 115 of a power tool 100 is shown. The PCB 115 includes a configuration 1100 of circuit components. In this embodiment, the configuration 1100 includes FETs 130 (e.g., FETs 130-1, FETs 130-2, and FETs 130-3) and a current sensing resistor network 1110, which includes current sensing resistors (e.g., current sensing resistors 1112, current sensing resistors 1114, and current sensing resistors 1116). In some embodiments, FET 130-1 is associated with a first phase of a motor 105, FET 130-2 is associated with a second phase of the motor 105, and FET 130-3 is associated with a third phase of the motor 105. The FETs 130 are mounted to, for example, a first surface 115a of the PCB 115 and are positioned to form a trace 1118 on the PCB 115. FET 130 - 2 is positioned equidistantly between FET 130 - 1 and FET 130 - 3 on formed line 1118 .

[0088] The current sensing resistor (“CSR”) network 1110 is configured to measure the current transmitted to the load (e.g., the motor 105) via the FET 130. Due to the space constraints on the first surface 115a of the PCB 115, the current sensing resistors of the current sensing resistor network 1110 are mounted to the first surface 115a of the PCB 115 and are positioned to form corresponding lines 1120, 1122, 1124 on the PCB 115 near the FET 130-3. The current sensing resistor 1114 is positioned equidistantly between the current sensing resistor 1112 and the current sensing resistor 1116, and the lines 1120, 1122, 1124 formed by the current sensing resistors 1112-1116 are oriented to form an angle (e.g., approximately 45 degrees) with the line 1118 of the formed FET 130. In addition, a current sensing tap is applied to the center current sensing resistor (e.g., the current sensing resistor 1114) of the current sensing resistor network 1110.

[0089] In this embodiment, configuration 1100 causes the hardware over-current ("HWOC") trip point of the power tool 100 to be lower than an expected threshold (e.g., approximately 80% of the expected trip point). The effect of circuit board impedance is that the effective impedance of the CSR network 1110 is different depending on the phase activated. In some examples, the circuit board impedance of PCB 115 between the current sensing resistors causes the effective impedance of the current sensing resistor to rise to a suitable level. However, if the effective resistance of the current sensing resistor increases (e.g., from 0.33 mΩ to 0.43 mΩ), the HWOC trip point returns to the expected value.

[0090] In an example, the PCB 115 includes a single-layer circuit board that has an expected impedance difference of 9% in the corresponding effective CSR impedance between the first phase 130-1 of the FET and the third phase 130-3 of the FET. Therefore, the stall currents of the FET 130-1 and the FET 130-3 are theoretically 9% different, and the effective CSR impedance of the third phase 130-3 of the FET is expected to be approximately equal to, for example, 406 mΩ. In this example, the current sensing resistor network 1110 measures the current of the third phase 130-3 of the FET (e.g., 217 amperes) and the current of the first phase 130-1 of the FET (e.g., 207 amperes), which is a 5% difference in the stall currents of the FET 130-1 and the FET 130-3, resulting in a measured effective CSR impedance (e.g., 0.415 mΩ) that is higher than the effective CSR impedance of the third phase 130-3 of the FET (e.g., 406 mΩ).

[0091] Fig. 11B A linear center mounted current sensing resistor configuration 1130 of a component of a PCB 115 of a power tool 100 is shown. The PCB 115 includes a linear current sensing resistor network configuration. In this embodiment, the linear configuration 1130 includes a FET 130 and a current sensing resistor network 1132, which includes a current sensing resistor. In the example, FET 130-1 is associated with a first phase of the motor 105, FET 130-2 is associated with a second phase of the motor 105, and FET 130-3 is associated with a third phase of the motor 105. The FET 130 is mounted to a first surface 115a of the PCB 115 and is positioned to form a line 1118 (e.g., a line 1118) on the PCB 115. Fig.11A ), or may be angled relative to each other (e.g., FET 130-1 and FET 130-3 form an angle of approximately 45 degrees relative to FET 130-2). In some embodiments, FET 130-1 is positioned to form an angle (e.g., approximately 135 degrees) relative to formed line 1118, and FET 130-3 is angled relative to formed line 1118 (e.g., approximately 45 degrees).

[0092] The current sensing resistor network 1132 is configured to measure the current transmitted to the load (e.g., the motor 105) via the FET 130. Due to the phase balance and size constraints of the configuration 1100, the current sensing resistors of the current sensing resistor network 1132 are mounted to the first surface 115a of the PCB 115 and are positioned to form three parallel lines 1120, 1122, 1124 on the PCB 115. The lines 1120, 1122, 1124 of the current sensing resistors are formed parallel to each other and perpendicular to the line 1118 of the FET 130. The current sensing resistor 1114 is positioned equidistantly between the current sensing resistor 1112 and the current sensing resistor 1116 of the current sensing resistor network 1132. The stack height or length of the current sensing resistor network 1132 is close to and parallel to the FET 130-2. Additionally, a current sensing tap is applied to a center current sensing resistor (eg, current sensing resistor 1114 ) of the current sensing resistor network 1132 .

[0093] In some examples, the current sensing resistor network 1132 near the FET 130-2 is configured to balance the capacitor return paths on both sides of the inverter bridge circuit. The estimated phase difference of the current sensing resistor network 1132 is about 12%, where the first phase 130-1 of the FET and the third phase 130-3 of the FET have a CSR impedance of, for example, .404 mΩ, and the second phase 130-2 of the FET has a CSR impedance of, for example, .362 mΩ.

[0094] Fig. 11C A center mounted current sensing resistor configuration 1150 of a component of a PCB 115 of a power tool 100 is shown. The PCB 115 includes a center current sensing resistor network configuration. In this embodiment, the center configuration 1150 includes FETs 130 and a current sensing resistor network 1152, which includes current sensing resistors. In the example, FET 130-1 is associated with a first phase of the motor 105, FET 130-2 is associated with a second phase of the motor 105, and FET 130-3 is associated with a third phase of the motor 105. The FETs 130 are mounted to a first surface 115a of the PCB 115 and are positioned to form a line 1118 (e.g., a line 1118) on the PCB 115. Fig.11A ), or may be angled relative to each other (e.g., FET 130-1 and FET 130-3 form an angle of approximately 45 degrees relative to FET 130-2). In some embodiments, FET 130-1 is positioned to form an angle (e.g., approximately 135 degrees) relative to formed line 1118, and FET 130-3 is angled relative to formed line 1118 (e.g., approximately 45 degrees).

[0095] The current sensing resistor network 1152 is configured to measure the current transmitted to the load (e.g., the motor 105) via the FET 130. Due to the phase balance and size constraints of the configuration 1100, the current sensing resistors of the current sensing resistor network 1152 are mounted to the first surface 115a of the PCB 115. The current sensing resistor 1112 is positioned close to the FET 130-2 and is angled (e.g., approximately 135 degrees) relative to the line 1118 of the FET 130 formed. The current sensing resistor 1116 is positioned close to the FET 130-2 and is angled (e.g., approximately 45 degrees) relative to the line 1118 of the FET 130 formed. The current sensing resistor 1114 is positioned close to and is angled (e.g., approximately 90 degrees or perpendicular) relative to the line 1118 of the FET 130 formed. Current sensing resistor 1114 is also positioned equidistantly between current sensing resistor 1112 and current sensing resistor 1116 and forms an angle of approximately 45 degrees relative to current sensing resistors 1112 and 1116 .

[0096] Various embodiments of the present disclosure recognize that the CSR network layout needs to be such that the size impact of the PCB assembly is reduced and the impedance difference between phases is reduced. In some implementations, the current sensing resistor network 1152 enables the size of the PCB 115 to be compact and improves phase balance at the expense of increasing the length and width of the current sensing resistor network 1152. The current sensing resistor network 1152 increases the CSR output impedance that is always present and reduces the input impedance to each CSR, which reduces the impedance difference based on the phase, regardless of which phase the current path is from.

[0097] For a minor sacrifice in the length and width of the CSR network 1152, the width of the PCB 115 can be slightly reduced due to the impedance paths at the ends of the two flanking CSRs (e.g., current sense resistor 1112 and current sense resistor 1116). For example, the estimated phase impedance difference of the current sense resistor network 1152 is approximately .2%, where the effective phase impedance of the first phase 130-1 of the FET and the third phase 130-3 of the FET is, for example, .405 mΩ, and the effective phase impedance of the second phase 130-2 of the FET is, for example, .404 mΩ.

[0098] Thus, the embodiments described herein provide, among other things, a power tool having a current sensing resistor network. Various features and advantages are set forth in the appended claims.

Claims

1. An electric tool comprising: A printed circuit board is positioned within the housing of the power tool, the printed circuit board comprising: a switch network mounted to the printed circuit board, the switch network electrically coupled to the brushless DC motor; and A current sensing resistor network mounted to the printed circuit board, the current sensing resistor network being configured to measure current delivered to the brushless DC motor, characterized in that, The current sensing resistor network includes three current sensing resistors spaced equidistantly from each other.

2. The electric tool according to claim 1, wherein: The current sensing resistor network is positioned on the printed circuit board proximate to the switch network.

3. The electric tool according to claim 2, wherein: The current sensing resistor network includes a first current sensing resistor, a second current sensing resistor, and a third current sensing resistor, and wherein the second current sensing resistor is positioned equidistantly between the first current sensing resistor and the third current sensing resistor.

4. The electric tool according to claim 3, wherein: The second current sensing resistor is positioned to form an angle of approximately 45 degrees with respect to the first current sensing resistor and the third current sensing resistor.

5. The electric tool according to claim 4, wherein: The switch network includes a first field effect transistor associated with a first phase of the brushless DC motor, a second field effect transistor associated with a second phase of the brushless DC motor, and a third field effect transistor associated with a third phase of the brushless DC motor.

6. The electric tool according to claim 5, wherein: The first field effect transistor, the second field effect transistor, and the third field effect transistor are positioned to form a line proximate to the current sensing resistor network.

7. The electric tool according to claim 6, wherein: The first current sensing resistor is positioned at an angle of approximately 135 degrees relative to the line formed near the current sensing resistor network, the second current sensing resistor is positioned at an angle of approximately 90 degrees relative to the line formed near the current sensing resistor network, and the third current sensing resistor is positioned at an angle of approximately 45 degrees relative to the line formed near the current sensing resistor network.

8. A printed circuit board, comprising: a switch network mounted to the printed circuit board; as well as A current sensing resistor network mounted to the printed circuit board, the current sensing resistor network being configured to measure a current delivered to the brushless DC motor based on the switch network, characterized in that, The current sensing resistor network includes three current sensing resistors spaced equidistantly from each other.

9. The printed circuit board according to claim 8, wherein: The current sensing resistor network includes a first current sensing resistor, a second current sensing resistor, and a third current sensing resistor, and wherein the second current sensing resistor is positioned equidistantly between the first current sensing resistor and the third current sensing resistor.

10. The printed circuit board according to claim 9, wherein The second current sensing resistor is positioned to form an angle of approximately 45 degrees with respect to the first current sensing resistor and the third current sensing resistor.

11. The printed circuit board according to claim 10, wherein: The switch network includes a first field effect transistor associated with a first phase of the brushless DC motor, a second field effect transistor associated with a second phase of the brushless DC motor, and a third field effect transistor associated with a third phase of the brushless DC motor.

12. The printed circuit board according to claim 11, wherein The first field effect transistor, the second field effect transistor, and the third field effect transistor are positioned to form a line proximate to the current sensing resistor network.

13. The printed circuit board according to claim 12, wherein: The first current sensing resistor is positioned at an angle of approximately 135 degrees relative to the line formed near the current sensing resistor network, the second current sensing resistor is positioned at an angle of approximately 90 degrees relative to the line formed near the current sensing resistor network, and the third current sensing resistor is positioned at an angle of approximately 45 degrees relative to the line formed near the current sensing resistor network.

14. The printed circuit board according to claim 13, wherein: The first field effect transistor is positioned at an angle of approximately 135 degrees relative to the line formed near the current sensing resistor network, the second field effect transistor is positioned at an angle of approximately 90 degrees relative to the line formed near the current sensing resistor network, and the third field effect transistor is positioned at an angle of approximately 45 degrees relative to the line formed near the current sensing resistor network.

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