Electronic spindle lock for power tool

Abstract

To provide spindle locking technique that reduces the length, cost and complexity of the overall design of a power tool.SOLUTION: Electronic spindle lock for a power tool is provided. One embodiment provides a power tool including: a housing; a bit receiving portion provided on the housing for receiving a power tool bit; a motor within the housing configured to rotate the bit receiving portion; and a controller coupled to the motor. The controller is configured to enter an electronic spindle lock mode, and detect rotation of the bit receiving portion in a first direction. The controller is also configured to control the motor to rotate in a second direction in response to detecting rotation of the bit receiving portion in the first direction.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 977,596, filed February 17, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] A conventional power tool includes a chuck that receives a tool bit of the power tool. The chuck includes chuck jaws that hold the tool bit. To receive the tool bit, the chuck is manually rotated by a user to loosen the chuck jaws. After the tool bit is interposed between the chuck jaws, the chuck is rotated again to clamp the chuck jaws around the tool bit. Summary of the Invention [Problem to be solved by the invention]

[0003] Mechanical spindle locks are traditionally provided to resist or prevent rotation of the power tool drivetrain when a user manually applies torque to the chuck to tighten or loosen the chuck jaws. Mechanical spindle locks are mechanical components that are added between the power tool drivetrain and the chuck. As a result, mechanical spindle locks add length, cost, and complexity to the overall design of the power tool.

[0004] The embodiments described herein provide a spindle locking technique that reduces the length, cost, and complexity of the overall design of a power tool. [Means for solving the problem]

[0005] A power tool described herein includes a housing, a bit receiving portion disposed in the housing, a motor within the housing configured to rotate the bit receiving portion, and a controller coupled to the motor. The controller is configured to enter an electronic spindle lock mode and, in response to entering the electronic spindle lock mode, activate a spindle lock control loop. The spindle lock control loop includes detecting rotation of the bit receiving portion in a first direction and, in response to detecting rotation of the bit receiving portion in the first direction, controlling the motor to rotate in a second direction.

[0006] In some aspects, the power tool further includes a trigger, and the controller is further configured to enter an electronic spindle lock mode when the trigger is released to stop operation of the power tool.

[0007] In some aspects, the controller is further configured to determine that the power tool is stopped, activate a spindle lock control loop in response to determining that the power tool is stopped, detect movement of the power tool using one or more sensors for a delay time after activating the spindle lock control loop, and enter a sleep mode if no movement of the power tool is detected after the delay time.

[0008] In some embodiments, the one or more sensors include at least one selected from the group consisting of an accelerometer, a capacitive sensor, and an inductive sensor.

[0009] In some aspects, the spindle lock control loop is deactivated in the sleep mode.

[0010] In some aspects, the controller is further configured to determine when a wake-up signal is received when in sleep mode, perform normal motor operation if the wake-up signal is received from the trigger, and activate a spindle lock control loop if the wake-up signal is received from one or more sensors.

[0011] In some aspects, normal motor operation includes controlling the motor according to trigger depresses of a trigger.

[0012] In some aspects, the power tool further includes an electronic spindle lock button, and the controller is further configured to enter the electronic spindle lock mode when the electronic spindle lock button is actuated.

[0013] In some aspects, rotation of the bit-receiving portion in the first direction is detected based on sensing a parameter indicative of rotation of the bit-receiving portion.

[0014] In some aspects, the parameter is rotor position.

[0015] In some embodiments, the motor rotates in a second direction to maintain a stationary rotational position.

[0016] In some aspects, the controller is further configured to enforce a maximum time limit for the electronic spindle lock mode, such that the spindle lock control loop ceases operation after the maximum time limit.

[0017] In some aspects, the electronic processor is further configured to detect an impulse when in the electronic spindle lock mode and to disable the spindle lock control loop in response to detecting the impulse.

[0018] In some aspects, the power tool further includes a battery pack that provides operating power to the motor.

[0019] In some aspects, the electronic processor is further configured to detect a voltage level of the battery pack and, in response to the voltage level being below a predetermined low voltage threshold, disable the spindle lock control loop.

[0020] A power tool described herein includes a housing, a bit-receiving portion disposed in the housing, a motor within the housing configured to rotate the bit-receiving portion, and a controller coupled to the motor. The controller is configured to enter an electronic spindle lock mode and to control the motor as a brake in response to entering the spindle lock mode. The motor generates a counter torque in response to a torque applied to the bit-receiving portion.

[0021] In some aspects, the power tool further includes a trigger, and the controller is further configured to enter an electronic spindle lock mode when the trigger is released to stop operation of the power tool.

[0022] In some aspects, the power tool further includes an electronic spindle lock button, and the controller is further configured to enter the electronic spindle lock mode when the electronic spindle lock button is actuated.

[0023] In some aspects, controlling the motor as a brake includes shorting the motor windings of the motor.

[0024] In some aspects, the power tool further includes a metal oxide semiconductor field effect transistor (MOSFET) coupled across the motor windings.

[0025] In some aspects, the power tool further includes a battery pack providing operating power to the motor, the MOSFET being a depletion mode MOSFET that is normally closed when the battery pack is removed, and the controller is further configured to open the depletion mode MOSFET when the battery pack is connected to the power tool.

[0026] In some aspects, the power tool further includes a battery pack that provides operating power to the motor, the motor further including a secondary winding configured to generate a voltage when the bit receiving portion is rotated relative to the housing and the battery pack is disconnected from the power tool.

[0027] In some aspects, the voltage on the secondary winding is used to charge a capacitor, and when the capacitor becomes sufficiently charged, the capacitor is used to short out a motor winding of the motor.

[0028] A method described herein for operating an electronic spindle lock of a power tool includes entering an electronic spindle lock mode with a controller of the power tool, and in response to entering the electronic spindle lock mode with the controller, initiating a spindle lock control loop including detecting rotation of a bit receiving portion of the power tool in a first direction, and in response to detecting rotation of the bit receiving portion in the first direction, controlling a motor of the power tool to rotate in a second direction.

[0029] In some aspects, the method further includes detecting, with the controller, a release of a trigger of the power tool to stop the power tool, and entering an electronic spindle lock mode if the trigger is released.

[0030] In some aspects, the method further includes determining that the power tool is stopped; activating a spindle lock control loop in response to determining that the power tool is stopped; detecting movement of the power tool using one or more sensors for a delay time after activating the spindle lock control loop; and entering a sleep mode if no movement of the power tool is detected after the delay time.

[0031] In some embodiments, the one or more sensors include at least one selected from the group consisting of an accelerometer, a capacitive sensor, and an inductive sensor.

[0032] In some aspects, the method further includes disabling operation of a spindle lock control loop in the sleep mode.

[0033] In some aspects, the method further includes determining when in sleep mode that a wake-up signal is received, performing normal motor operation if the wake-up signal is received from the trigger, and activating a spindle lock control loop if the wake-up signal is received from the one or more sensors.

[0034] In some aspects, normal motor operation includes controlling the motor according to trigger depresses of a trigger.

[0035] In some aspects, the method further includes detecting activation of an electronic spindle lock button, and entering an electronic spindle lock mode if the electronic spindle lock button is activated.

[0036] In some aspects, the method further includes detecting rotation of the bit-receiving portion in the first direction based on sensing a parameter indicative of rotation of the bit-receiving portion.

[0037] In some aspects, the parameter is rotor position.

[0038] In some embodiments, the motor rotates in a second direction to maintain a stationary rotational position.

[0039] In some aspects, the method further includes enforcing a maximum time limit for the electronic spindle lock mode, such that the spindle lock control loop ceases operation after the maximum time limit.

[0040] In some aspects, the method further includes detecting an impulse when in the electronic spindle lock mode, and disabling the spindle lock control loop in response to detecting the impulse.

[0041] In some aspects, the method further includes detecting a voltage level of a battery pack providing operating power to the motor, and disabling the spindle lock control loop in response to the voltage level being below a predetermined low voltage threshold.

[0042] A method described herein for operating an electronic spindle lock of a power tool includes entering an electronic spindle lock mode with a controller of the power tool and, in response to entering the spindle lock mode, controlling a motor of the power tool with the controller as a brake, the motor providing a counter torque in response to torque applied to a bit receiving portion.

[0043] In some aspects, the method further includes detecting, with the controller, a release of a trigger of the power tool to stop the power tool, and entering an electronic spindle lock mode if the trigger is released.

[0044] In some aspects, the method further includes detecting activation of an electronic spindle lock button, and entering an electronic spindle lock mode if the electronic spindle lock button is activated.

[0045] In some aspects, controlling the motor as a brake includes shorting a motor winding of the motor.

[0046] In some aspects, the method further includes connecting a metal oxide semiconductor field effect transistor (MOSFET) across the motor windings.

[0047] In some aspects, the MOSFET is a depletion mode MOSFET that is normally closed when a battery pack is removed from the power tool, and the method further includes opening the depletion mode MOSFET when the battery pack is connected to the power tool.

[0048] In some aspects, the method further includes generating a voltage on a secondary winding of the motor when the bit receiving portion is rotated relative to the housing of the power tool and when a battery pack of the power tool is disconnected from the power tool.

[0049] In some aspects, the method further includes charging a capacitor with the voltage on the secondary winding and then shorting a motor winding of the motor when the capacitor is sufficiently charged.

[0050] A power tool described herein includes a housing, a bit-receiving portion disposed in the housing for receiving a power tool bit, a motor within the housing configured to rotate the bit-receiving portion, and a controller coupled to the motor. The controller is configured to enter an electronic spindle lock mode and detect rotation of the bit-receiving portion in a first direction. The controller is also configured to control the motor to rotate in a second direction in response to detecting rotation of the bit-receiving portion in the first direction.

[0051] A method described herein is provided for operating an electronic spindle lock of a power tool. The method includes entering an electronic spindle lock mode with a controller of the power tool and detecting rotation of a bit receiving portion of the power tool in a first direction. The method also includes controlling, with the controller, a motor of the power tool to rotate in a second direction in response to detecting rotation of the bit receiving portion in the first direction.

[0052] A method described herein is provided for operating an electronic spindle lock of a power tool. The method includes entering an electronic spindle lock mode with a controller of the power tool and configuring a motor of the power tool as a brake in response to entering the electronic spindle lock mode. The method also includes using the motor to generate a counter torque in response to torque applied to a bit receiving portion.

[0053] Before describing any embodiment in detail, it is to be understood that the embodiment is not limited in its application to the details of the construction and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The embodiments can be practiced or carried out in various ways. It is also to be understood that the phrases and terms used herein are for purposes of description and should not be regarded as limiting. The use of "containing", "including", "having" and variations thereof is intended to encompass the items listed thereafter and their equivalents as well as additional items. Unless otherwise expressly stated or limited, the terms "mounted", "connected", "supported" and "coupled" and variations thereof are used in the broadest sense and include both direct and indirect mounting, connecting, supporting, and coupling.

[0054] In addition, it should be understood that the embodiments may include hardware, software, and electronic components or modules, which may be illustrated and described as if the majority of the components were implemented solely in hardware for purposes of discussion. However, those skilled in the art will recognize based on reading this detailed description that in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored in a non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and / or an application-specific integrated circuit ("ASIC"). Thus, it should be noted that a number of hardware and software-based apparatuses and a number of different structural components may be utilized to implement the embodiments. For example, the "server" and "computing device" described herein may include one or more processing units, one or more computer-readable media modules, one or more input / output interfaces, and various connections (e.g., a system bus) connecting the components together.

[0055] Other aspects of the embodiments will become apparent by consideration of the detailed description and accompanying drawings. [Brief description of the drawings]

[0056] [Figure 1] 1 illustrates a handheld power tool according to some embodiments. [Figure 2A] 1 illustrates a handheld power tool according to some embodiments. [Figure 2B] 1 illustrates a handheld power tool according to some embodiments. [Figure 3A] 1 illustrates a handheld power tool according to some embodiments. [Figure 3B] 1 illustrates a handheld power tool according to some embodiments. [Figure 4] 4 illustrates a battery pack for powering the power tools of FIGS. 1-3, according to some embodiments. [Diagram 5] 1 illustrates a control system for a power tool according to some embodiments. [Figure 6] FIG. 1 is a flow diagram of a method for operating an electronic spindle lock according to some embodiments. [Figure 7] FIG. 1 is a flow diagram of a method for operating an electronic spindle lock according to some embodiments. [Figure 8] 1 illustrates a spindle lock control loop according to some embodiments. [Figure 9] 6 illustrates torque signatures observed on the hand-held power tools of FIGS. 1-5 according to some embodiments. [Figure 10] 6 illustrates torque signatures observed on the hand-held power tools of FIGS. 1-5 according to some embodiments. [Figure 11] 6 illustrates torque signatures observed on the hand-held power tools of FIGS. 1-5 according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] The embodiments described herein relate to an electronic spindle lock implemented by control of the power tool motor to resist or prevent movement of the power tool drive train when the bit receiving portion is rotated.

[0058] The cordless handheld power tool shown in FIG. 1 is a hammer drill / driver ("hammer drill") 100. The hammer drill 100 includes an upper body 105, a handle portion 110, a battery pack receiving portion 115, a mode selection portion 120 (e.g., for selecting among a drilling mode, a driving mode, a hammer mode, etc.), a torque adjustment dial or ring 125, an output driver or mechanism (e.g., a chuck) 130, a forward / reverse selection button 135, and a trigger 140. The battery pack receiving portion 115 receives a battery pack (e.g., battery pack 400 of FIG. 4). The chuck 130 receives one of a number of tool bits for use in drilling and driving operations with the hammer drill 100. The chuck 130 includes chuck jaws 150 that open and close (e.g., loosen and tighten) to receive and release the tool bit. To open the chuck jaws 150, a user manually rotates the chuck 130 in a first, or counterclockwise direction. To close the chuck jaws 150, a user manually rotates the chuck 130 in a second, or clockwise direction. Conventional hammer drills include a mechanical spindle lock provided between the chuck 130 and the power tool drive train to resist or prevent rotation of the drive train when a user manually rotates the chuck 130. In the present hammer drill 100, the mechanical spindle lock may be eliminated.

[0059] The cordless handheld power tool shown in Figures 2A and 2B is a saw (e.g., a circular saw) 200. The circular saw 200 includes a saw body 205, a handle portion 215, a battery pack receiving portion 220, a spindle lock button 225, a trigger 230, a blade bolt 240, a blade flange 245, and a blade accessory 250. The battery pack receiving portion 220 receives a battery pack (e.g., the battery pack 400 of Figure 4). As shown in Figure 2B, the blade accessory 250 is disposed between the blade flange 245 and a spindle 255. The blade bolt 240 secures the blade flange 245 and the blade accessory 250 to the spindle 255. The spindle 255 is rotated by a motor of the circular saw 200 to rotate the blade accessory 250 for a cutting action. To remove the blade accessory 250, a user presses the spindle lock button 225 and, while holding the spindle lock button 225, manually rotates the blade bolt 240 counterclockwise using a wrench provided on the circular saw 200. To install the blade accessory 250, a user places the blade accessory 250 on the spindle 255 and, while holding the spindle lock button 225, manually rotates the blade bolt 240 clockwise using a wrench. The spindle lock button 225 activates a mechanical spindle locking mechanism (not shown) to resist or prevent rotation of the spindle 255 when a user manually tightens or loosens the blade bolt 240. In the circular saw 200, the mechanical spindle locking mechanism may be removed.

[0060] The cordless handheld power tool shown in FIG. 3 is a grinder 300. The grinder 300 includes a grinder body 305, a handle portion 310, a side handle 315, a battery pack receiving portion 320, a spindle lock button 325, a trigger 330, a guard 335, and a grinder accessory (e.g., a grinding wheel, abrasive disk, etc.) 340. The battery pack receiving portion 320 receives a battery pack (e.g., the battery pack 400 of FIG. 4). As shown in FIG. 3B, the grinder accessory 340 is mounted on a spindle 345 between a flange 350 and a flange nut 355. The flange nut 355 secures the grinder accessory 340 to the spindle 345. The spindle 345 is rotated by a motor of the grinder 300 to rotate the grinder accessory 340 for grinding or polishing operations. To remove the grinder accessory 340, a user presses the spindle lock button 325 and, while holding the spindle lock button 325, manually rotates the flange nut 355 in a counterclockwise direction. To install the grinder accessory 340, a user places the grinder accessory 340 on the spindle 345 and, while holding the spindle lock button 325, manually rotates the flange nut 355 in a clockwise direction. The spindle lock button 325 activates a mechanical spindle locking mechanism (not shown) to resist or prevent rotation of the spindle when a user manually tightens or loosens the flange nut 355. In the present grinder 300, the mechanical spindle locking mechanism may be removed.

[0061] FIG. 4 shows a battery pack 400 including a housing 405 and an interface portion 410 for connecting the battery pack 400 to a device (e.g., power tool 100, 200, 300). In some embodiments, the battery pack 400 has a nominal voltage of about 18 volts (V) with a maximum voltage of about 20V. In other embodiments, the battery pack 400 may have other nominal and maximum voltages (e.g., 12V-14.4V, 36V-40V, etc.). The same battery pack 400 may be used to power each of the power tool devices 100, 200, 300. As a result, a single battery pack 400 may power the entire power tool system, allowing compatibility between the different power tools 100, 200, 300.

[0062] 5 illustrates a control system for the power tools 100, 200, 300. The control system includes a controller 500. The controller 500 is electrically and / or communicatively connected to various modules or components of the power tools 100, 200, 300. For example, the illustrated controller 500 is electrically connected to a motor 505, a battery pack interface 510, a trigger switch 515 (connected to a trigger 520), one or more sensors or sensing circuits 525, one or more indicators 530, a user input module 535, a power input module 540, and a FET switching module 550 (e.g., including a plurality of switching FETs). The controller 500 includes a combination of hardware and software operable to, among other things, control the operation of the power tools 100, 200, 300, monitor the operation of the power tools 100, 200, 300, activate one or more indicators 530 (e.g., LEDs), etc.

[0063] The controller 500 includes a number of electrical and electronic components that provide power, operational control, and protection to the controller 500 and / or the components and modules within the power tools 100, 200, 300. For example, the controller 500 includes, among other things, a processing unit 555 (e.g., a microprocessor, a microcontroller, an electronic processor, an electronic controller, or another suitable programmable device), a memory 560, an input unit 565, and an output unit 570. The processing unit 555 includes, among other things, a control unit 575, an ALU 580, and a number of registers 585 (shown as a group of registers in FIG. 5 ), and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 555, the memory 560, the input unit 565, and the output unit 570, as well as the various modules or circuits connected to the controller 500, are connected by one or more control buses and / or data buses (e.g., a common bus 590). The control and / or data buses are shown generally in FIG. 5 for purposes of illustration. The use of one or more control and / or data buses for interconnection and communication between the various modules, circuits, and components will be apparent to those of skill in the art in view of the embodiments described herein. In some embodiments, the controller 500 is implemented in part or in whole in a field programmable gate array (FPGA), application specific integrated circuit (ASIC), or the like.

[0064] The memory 560 is a non-transitory computer-readable medium, including, 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, optical, physical, or electronic memory devices. The processing unit 555 is coupled to the memory 560 and executes software instructions, which may be stored in the RAM of the memory 560 (e.g., during execution), in the ROM of the memory 560 (e.g., typically permanently), or in another non-transitory computer-readable medium, such as another memory or a disk. Software included in the implementation of the power tools 100, 200, 300 may be stored in the memory 560 of the controller 500. The software may include, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 500 is configured to read and execute instructions from the memory 560, which may be associated with the control processes and methods described herein, among other things. In other configurations, the controller 500 includes additional, fewer, or different components.

[0065] The battery pack interface 510 includes a combination of mechanical (e.g., rails, grooves, latches, etc.) and electrical (e.g., one or more terminals) components configured and operable to interface (e.g., mechanically, electrically, and communicatively connect) the power tool 100, 200, 300 with a battery pack (e.g., the battery pack 400). For example, power provided to the power tool 100, 200, 300 by the battery pack 400 is provided to the power input module 540 via the battery pack interface 510. The power input module 540 includes a combination of active and passive components to condition and control the power received from the battery pack 400 before the power is provided to the controller 500. The battery pack interface 510 also provides power to the FET switching module 550, which is switched by the switching FET to selectively provide power to the motor 505. The battery pack interface 510 also includes a communication line 595, for example, to provide a communication line or link between the controller 500 and the battery pack 400.

[0066] The indicators 530 may include, for example, one or more light emitting diodes ("LEDs"). The indicators 530 may be configured to display a status of or information related to the power tool 100, 200, 300. For example, the indicators 530 may be configured to indicate a measured electrical characteristic of the power tool 100, 200, 300, a device status, etc. The user input module 535 is operably coupled to the controller 500 to select, for example, a forward or reverse operating mode, a torque and / or speed setting of the power tool 100, 200, 300 (e.g., with torque and / or speed switches), etc. In some embodiments, the user input module 535 includes a combination of digital and analog input or output devices necessary to achieve a desired level of operation of the power tool 100, 200, 300, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc.

[0067] The motor 505 is, for example, a brushless direct current (BLDC) motor. Operating power to the motor 505 is provided via a FET switching module 550. The controller 500 controls the FET switching module 550 to control the amount of power delivered to the motor 505 to rotate the motor based on one or more inputs received by the controller 500. For example, the controller 500 receives the amount of trigger pull from the trigger 520 and the rotor position from a Hall effect sensor of the motor 505 to control the activation and pulse width modulation (PWM) duty ratio of the FETs of the FET switching module 550. The PWM duty ratio may be controlled in proportion to the amount of trigger pull to provide different operating speeds of the motor 505 based on the trigger pull.

[0068] The trigger switch 515 is coupled to a trigger 520 (e.g., trigger 140, 230, 330) to control the power provided to the motor 505 through a FET switching module 550. In some embodiments, the amount of trigger pull detected by the trigger switch 515 is related to or corresponds to a desired rotational speed of the motor 505. In other embodiments, the amount of trigger pull detected by the trigger switch 515 is related to or corresponds to a desired torque.

[0069] As discussed above, mechanical spindle locking mechanisms are used in conventional power tools to resist or prevent rotation of the drive train (e.g., spindle 255, 345) when the bit receiving portion (e.g., chuck 130, blade bolt 240, and flange nut 355) is manually rotated by a user. However, mechanical spindle locking mechanisms add to the form factor, cost, and complexity of the power tools 100, 200, 300. Embodiments of the power tools 100, 200, 300 eliminate the need for a mechanical spindle lock. Instead, the power tools 100, 200, 300 implement an electronic spindle lock by controlling the motor 505 to resist or prevent movement of the drive train when the bit receiving portion is rotated.

[0070] FIG. 6 is a flow diagram of an example method 600 for operating an electronic spindle lock for a power tool 100, 200, 300. In the illustrated embodiment, the method 600 includes entering (at block 610) an electronic spindle lock mode. In some embodiments, the electronic spindle lock mode may be entered automatically by the controller 500. For example, the power tool 100 enters the electronic spindle lock mode when the trigger is released to stop operation of the power tool 100. The controller 500 detects that the trigger has been released and enters the electronic spindle lock mode. In other embodiments, the electronic spindle lock mode is entered manually, for example, based on user input. For example, the power tool 200, 300 may enter the electronic spindle lock mode when the spindle lock button 225, 325 is activated by a user. In one embodiment, the electronic spindle lock mode is activated only while the spindle lock button 225, 325 is activated. In other embodiments, the power tool 200, 300 switches between an electronic spindle lock mode and a normal mode (e.g., a mode in which the spindle is not locked and the motor rotates with the tool bit) when a user activates the spindle lock button 225, 325. In some embodiments, the spindle lock button 225, 325 may be a two-position switch that allows a user to select between the electronic spindle lock mode and the normal mode based on the position of the spindle lock button 225, 325.

[0071] The method 600 also includes detecting (at block 620) a rotation of the bit receiving portion (e.g., the chuck 130, the blade bolt 240, or the flange nut 355) in a first direction using the sensor 525. Detecting the rotation of the bit receiving portion includes, for example, detecting the rotation of the bit receiving portion relative to a housing of the power tool 100, 200, 300. The rotation may be detected based on sensing a parameter indicative of the rotation of the bit receiving portion. In some embodiments, the parameter is a rotor position of the motor 505. The rotation of the bit receiving portion may induce a rotation of a rotor of the motor 505. This rotor rotation may be used to detect that the bit receiving portion is rotating in a first direction (e.g., counterclockwise or clockwise). In a sensored brushless motor (e.g., including a Hall Effect sensor to detect rotor position), the Hall Effect sensor may be used to monitor the rotation of the bit receiving portion. In a sensorless brushless motor (e.g., not including a Hall effect sensor), a voltage induced in one or more coils of the motor 505 may be used to monitor the rotation of the bit-receiving portion. In other embodiments, the parameter is spindle position. A Hall effect sensor or rotational encoder may be provided on the spindle 255, 345 to detect the rotation of the spindle. In some embodiments, the parameter may be torque induced in the spindle 255, 345 or the motor 505. The torque may be measured using, for example, a torque transducer in the power tool 100, 200, 300.

[0072] The method 600 further includes controlling (at block 620) with the controller 500 to rotate the motor 505 in a second direction in response to detecting rotation of the bit-receiving portion in the first direction. The second direction is opposite to the first direction. For example, if the bit-receiving portion is rotated in a counterclockwise direction, the motor is rotated in a clockwise direction, and vice versa. The controller 500 controls the rotation of the motor 505 to counter the rotation of the bit-receiving portion. The motor 505 is controlled to maintain a stationary rotational position (i.e., 0 RPM). As described above, the controller 500 may provide a PWM signal to the FET switching module 550 to control the rotation of the motor 505. The controller 500 receives feedback from a rotational position sensor (e.g., a Hall effect sensor in a sensored motor and a voltage sensor in a sensorless motor) and uses the feedback from the rotational position sensor to maintain the rotational position of the motor 505.

[0073] Method 600, and particularly blocks 610 and 620, are repeated to maintain the rotational position of motor 505. Method 600 is repeated until the electronic spindle lock mode is exited automatically or manually based on user input.

[0074] FIG. 7 is a flow diagram of an example method 700 for operating an electronic spindle lock for a power tool 100, 200, 300. In the illustrated embodiment, the method 700 includes using the controller 500 to determine (at block 710) that the power tool 100, 200, 300 is stopped. The controller 500 may continuously monitor the trigger switch 515 to determine whether the trigger is pulled. If the controller 500 does not receive a trigger signal from the trigger switch 515, the controller 500 determines that the power tool 100, 200, 300 is stopped. In some embodiments, the controller 500 determines that the power tool 100, 200, 300 is stopped based on a rotational position sensor of the motor 505. In particular, the controller 500 determines that the power tool 100, 200, 300 is stopped based on determining that the motor 505 is stationary in addition to or instead of determining that the trigger 520 is not pulled.

[0075] Method 700 also includes initiating (at block 720) a spindle lock control loop with controller 500 in response to determining that the tool is stopped. As described above with respect to FIG. 6, power tools 100, 200, 300 enter an electronic spindle lock mode when the tool is stopped. When in the spindle lock control loop, controller 500 monitors the rotation of the bit receiving portion. Controller 500 may execute the spindle lock control loop to maintain the rotational position of motor 505, as described below. In some embodiments, controller 500 implements the spindle lock control loop in blocks 610 and 620 of method 600.

[0076] The method 700 includes using the controller 500 to wait (at block 730) a delay time after activating the spindle lock control loop. The controller 500 executes the spindle lock control loop before or during waiting for the delay time. In some embodiments, the controller 500 starts a timer for the delay after the tool is stopped. In some embodiments, the delay time may be pre-programmed into the controller 500 during manufacture. In some embodiments, the delay time may be customizable by a user using an application on a connected smart device (e.g., a smartphone, a tablet computer, a laptop computer, a wearable device, etc.).

[0077] The method 700 includes configuring (at block 740) a sensor with the controller 500 to detect movement of the power tool 100, 200, 300 after a delay time. For example, the power tool 100, 200, 300 includes an accelerometer that detects movement of the power tool 100, 200, 300. The accelerometer may be deactivated during normal operation. The controller 500 may activate or configure the accelerometer to detect movement of the power tool 100, 200, 300 after the delay timer expires. The method 700 includes entering (at block 750) a sleep mode with the controller 500 after the delay time and if no movement of the tool 100, 200, 300 is detected. In the sleep mode, the controller 500 deactivates the spindle lock control loop to protect the battery. If movement of the tool 100, 200, 300 is detected in block 740, the method proceeds to block 760.

[0078] The method 700 includes determining (at block 760) with the controller 500 whether a wake-up signal is received. The controller 500 may receive the wake-up signal from an accelerometer, for example, if the accelerometer detects movement of the power tool 100, 200, 300. The controller 500 may also receive the wake-up signal if the trigger 520 is pulled. The method 700 includes determining (at block 770) with the controller 500 whether a wake-up signal is received from the trigger. If a wake-up signal is received from the trigger 520, the method 700 includes performing normal motor operation with the controller 500 (at block 780). The normal motor operation may include controlling the motor following the trigger pull and / or without performing motor control for spindle lock as described above. If a wake-up signal is not received from the trigger 520, ie, if a wake-up signal is received from an accelerometer or another sensor, the method 700 returns to block 720 to initiate the spindle lock control loop.

[0079] As discussed above, when the power tool 100, 200, 300 enters the electronic spindle lock mode (i.e., locked mode), the power tool 100, 200, 300 operates as if a traditional mechanical spindle lock had been activated. The electronic spindle lock is activated according to a spindle lock control loop. FIG. 8 shows an exemplary spindle lock control loop 800. In the illustrated embodiment, the spindle lock control loop 800 is a proportional integral loop. The spindle lock control loop 800 uses four-quadrant motor control to apply torque in the opposite direction of the bit-receiving portion's motion to maintain the physical position of the motor 505. The spindle lock control loop 800 is executed by the controller 500.

[0080] A spindle lock control loop 800 is implemented to provide control signals to the motor 505 for operation of the motor 505 in an electronic spindle lock mode. Feedback signals are received from the motor 505 and used to provide control signals to operate the motor 505. The feedback signals include, for example, a position feedback signal 805 and a speed feedback signal 810. In a sensored brushless motor, the position feedback signal 805 and the speed feedback signal 810 are received based on readings from a sensor (e.g., a Hall effect sensor) of the sensored brushless motor. For example, the Hall effect sensor indicates the position of the rotor of the motor 505 to the controller 500. Based on the position signal, the controller 500 may determine the position and speed of the rotor of the motor 505. In a sensorless brushless motor, the position feedback signal 805 and the speed feedback signal 810 are received based on readings from a voltage sensor of the sensorless brushless motor. The voltage sensor detects back EMF induced in one or more non-operating windings and provides an indication of the back EMF to the controller 500. The controller 500 determines the position and speed of the rotor of the motor 505 based on the back EMF signal from the voltage sensor. The voltage sensor may detect the back EMF in either the main winding of the motor 505 or a secondary dedicated winding of the motor 505. In some embodiments, the position and speed may also be detected using an external rotary encoder that detects the movement of the spindle or output shaft.

[0081] The spindle lock control loop 800 includes a position block 815 that stores a predicted position of the rotor. For example, the controller 500 may detect the position of the rotor when the tool stops and store the detected position in memory 560. The position block 815 retrieves and outputs predicted position information 820 stored in memory 560. The spindle lock control loop 800 includes a first error estimator 825 that receives the predicted position information 820 from the position block 815 and a position feedback signal 805. The first error estimator 825 outputs a position error signal 830 indicative of a discrepancy between the predicted position and the actual position of the rotor to a position loop controller 835. The position loop controller 835 outputs predicted velocity information 840 based on the position error signal 830.

[0082] The spindle lock control loop 800 includes a second error estimator 845 that receives predicted speed information 840 from the position loop controller 835 and the speed feedback signal 810. The second error estimator 845 outputs a speed error signal 850 indicative of the discrepancy between the predicted and actual speeds of the rotor to a speed loop controller 855. The speed loop controller 855 outputs predicted current information 860 based on the speed error signal 850.

[0083] The spindle lock control loop 800 includes a third error estimator 865 that receives expected current information 860 and a current feedback signal 870 from the speed loop controller 855. A current sensor may be provided by the motor 505 to detect the amount of current flowing through the motor 505 or the FET switching module 550. The current sensor is coupled to the controller 500 and provides the current information to the controller 500. The controller 500 determines the current flowing through the motor based on the current signal received from the current sensor. The third error estimator 865 outputs a current error signal 875 to a current loop controller 880 indicative of a discrepancy between the expected current and the actual current flowing through the motor 505. The current loop controller 880 outputs a PWM control signal 885 to a PWM amplifier 890.

[0084] The PWM amplifier 890 amplifies the PWM control signal 885 from the current loop controller 880 and outputs an amplified PWM control signal 895. The amplified PWM control signal 895 is provided to the FET switching module 550 to control the operation of the motor 505 to implement spindle lock as described above.

[0085] In some embodiments, the controller 500 enforces a maximum time limit on the time the motor 505 is controlled for spindle lock to protect the battery. For example, if the power tool 100, 200, 300 is in transit in a bag or in the back of a truck, movement may cause the accelerometer to detect that the power tool 100, 200, 300 has been lifted. In some instances, movement may result in the controller 500 detecting torque being applied to the bit receiving portion. In these cases, the controller may apply torque to maintain the rotational position for a maximum time limit, for example, up to 30 seconds. In other embodiments, the accelerometer may be a low power accelerometer that detects only gentle power tool movement by the user. In these embodiments, a maximum time limit may not be required.

[0086] In some embodiments, the electronic spindle lock is disabled when multiple rapid and short impulses are detected by the controller 500. FIG. 9 shows an example torque signature 900 detected when a user applies torque to the bit receiving portion but is unable to remove the tool bit. FIG. 10 shows an example torque signature 1000 detected when a user applies torque to the bit receiving portion and is successful in removing the tool bit. However, as shown in FIG. 11, a rapid and short impulse 1100 is detected when the power tool 100, 200, 300 is being transported, for example, in a bag or truck. When the controller 500 detects the rapid and short impulse 1100, the controller 500 may disable the electronic spindle lock to allow the rotor to rotate with the bit receiving portion (e.g., when the user is not gripping the power tool 100, 200, 300).

[0087] In some embodiments, rather than or in addition to an accelerometer, the power tool 100, 200, 300 may include a capacitive or inductive sensor in one of the handles or bit receiving portions of the power tool 100, 200, 300. The capacitive or inductive sensor detects when a user is gripping the handle or bit receiving portion and provides a signal to the controller 500. In some embodiments, the controller 500 enables the electronic spindle lock only in response to detecting that a user is gripping the handle or bit receiving portion.

[0088] In some embodiments, the bit receiving portion includes a gyroscope that monitors a user gripping and rotating the chuck to remove or replace a tool bit. The gyroscope readings may be used to both detect when an electronic spindle lock mode is entered and to detect rotation of the bit receiving portion in a first direction as described above. In some embodiments, the power tool 100, 200, 300 includes an air pressure sensor to detect when an orifice on the power tool 100, 200, 300 is covered. The air pressure sensor readings may be used to detect when an electronic spindle lock mode is entered as described above. The air pressure sensor may be provided, for example, in the handle, the bit receiving portion, and / or another component of the power tool 100, 200, 300.

[0089] In some embodiments, a human machine interface (HMI) element is used to detect a user gripping the bit receiving portion. For example, a push button may be used to allow a user to select the electronic spindle lock mode. In some embodiments, a light pipe is used to detect when a user is gripping the power tool 100, 200, 300. A light detector may be used in conjunction with the light pipe to identify when to enter the electronic spindle lock mode as described above. The light pipe and light detector may be located, for example, on the handle, bit receiving portion, and / or another component of the power tool 100, 200, 300. In some embodiments, a mechanical system is used to sense the back drive force caused by the user moving the bit receiving portion to enter the spindle lock mode.

[0090] In some embodiments, the electronic spindle lock is enabled only when the battery pack 400 is charged above the low voltage threshold. In other embodiments, the electronic spindle lock is enabled when the battery pack 400 is below the low voltage threshold but is charged above the deep discharge threshold. In these embodiments, the electronic spindle lock is disabled when the battery pack 400 is charged below the deep discharge threshold.

[0091] In some embodiments, the electronic spindle lock may be implemented in ways other than those described above. The embodiments described below may be implemented in addition to or instead of the active motor control embodiments described above. In particular, the embodiments described below are applicable when the power tool 100, 200, 300 is not coupled to the battery pack 400 or is not powered by the battery pack 400. For example, the motor windings may be shorted to implement the electronic spindle lock. That is, the motor 505 is configured as a brake in response to entering the spindle lock mode. The motor windings may be shorted when the power tool 100, 200, 300 is not connected to the battery pack 400. As a result, when torque is applied to the bit receiving portion, the motor provides sufficient resistance (i.e., counter torque) to prevent the rotor, and therefore the spindle, from rotating. Shorting the motor windings may be implemented by using depletion mode metal oxide semiconductor field effect transistors (MOSFETs). The depletion mode MOSFET is normally closed such that the depletion mode MOSFET remains closed when the battery pack 400 is disconnected from the power tool 100, 200, 300. The depletion mode MOSFET may be connected in parallel with an N-channel enhancement mode MOSFET used on the low side of the FET switching module 550. When the battery pack 400 is disconnected from the power tool 100, 200, 300, the gate-to-source voltage Vgs of the depletion mode MOSFET is zero. When the depletion mode MOSFET is closed, it creates a short circuit across the motor 505, creating a braking effect on the motor 505. When the battery pack 400 is connected, the depletion mode MOSFET is opened, thereby allowing the motor to operate normally upon trigger pull. Thus, when the battery pack 400 is removed, the electronic spindle lock is implemented by shorting the motor windings. When the battery pack 400 is connected, the electronic spindle lock is implemented by the proportional-integral control loop described above.

[0092] In some embodiments, a secondary winding with additional analog circuitry is added to the motor 505. The secondary winding quickly generates a voltage when the motor 505 rotates (e.g., by rotation of the tool bit or spindle) and the battery pack 400 is disconnected from the power tool 100, 200, 300. The voltage on the secondary winding may be used to charge a capacitor in the analog circuitry. When the capacitor is sufficiently charged, the capacitor may be used to close a low-side MOSFET of the FET switching module 550. The closed low-side MOSFET creates a low-resistance loop across the motor 505, similar to a depletion mode MOSFET. The low-resistance loop acts as a brake for the motor 505, thereby allowing the user to rotate the bit receiver without rotating the rotor. When the battery pack 400 is connected to the power tool 100, 200, 300, the controller 500 may disable the analog circuitry to prevent accidental shorting of the low-side MOSFET during operation.

[0093] In some embodiments, a small battery (e.g., a coin cell battery) may be used to short out the low-side MOSFET when the battery pack 400 is disconnected from the power tool 100, 200, 300 and motor rotation is detected. The small battery may be a rechargeable battery that can be charged the next time the battery pack 400 is connected to the power tool 100, 200, 300.

[0094] Thus, the embodiments described herein provide an electronic spindle lock for a power tool. Various features and advantages are set forth in the following claims.

Claims

1. Housing and A bit receiving portion provided on the housing; a motor within the housing configured to rotate the bit-receiving portion; a controller coupled to the motor, the controller comprising: entering an electronic spindle lock mode for controlling the motor to engage or disengage the bit receiving portion with a tool bit; initiating a spindle lock control loop in response to entering the electronic spindle lock mode; The spindle lock control loop is configured as follows: Detecting a position amount of the motor in a first direction; determining that the position amount differs from an expected position amount of the motor; and controlling the motor to generate a torque in a second direction, the torque maintaining a rotational position of the motor in response to determining that the position quantity differs from the expected position quantity of the motor. Power tools.

2. The controller: determining that the power tool is stopped; initiating the spindle lock control loop in response to determining that the power tool is stalled; using one or more sensors to detect movement of the power tool after a delay time after activating the spindle lock control loop; entering a sleep mode when no movement of the power tool is detected after the delay time; Further configured as follows: The power tool according to claim 1.

3. determining that the position amount differs from the expected position amount of the motor; The controller: and determining an expected rotor position of the motor rotor, the position quantity including an actual position of the rotor; The controller: determining a position error for the motor based on a difference between the predicted position of the rotor and the actual position of the rotor; determining an actual speed of the rotor of the motor; determining an expected speed of the rotor of the motor; determining a speed error for the motor based on a difference between the predicted speed of the rotor and the actual speed of the rotor. Further configured as follows: The power tool according to claim 2.

4. The controller: determining that a wake-up signal is received while in the sleep mode; performing normal motor operation when the wake-up signal is received from a trigger; initiating the spindle lock control loop when the wake-up signal is received from the one or more sensors. and wherein the normal motor operation includes controlling the motor in accordance with a trigger pull of the trigger. The power tool according to claim 2.

5. The controller: determining a predicted current of the motor based on the difference between the predicted speed of the rotor and the actual speed of the rotor; determining an actual amount of current in the motor; determining a current error for the motor based on a difference between the expected current in the motor and an actual amount of current in the motor; Further configured as follows: The power tool according to claim 3.

6. responsive to determining that the position amount differs from the expected position amount of the motor, controlling the motor to rotate in the second direction, the controller generating a pulse width modulated (PWM) signal based on the current error for the motor; Controlling the rotation of the motor based on the PWM signal. Further configured as follows: The power tool according to claim 5.

7. Further comprising an electronic spindle lock button; The controller is further configured to enter the electronic spindle lock mode when the electronic spindle lock button is actuated. The power tool according to claim 1.

8. The power tool of claim 1 , wherein the controller is further configured to enforce the maximum time limit for the electronic spindle lock mode such that the spindle lock control loop is stopped after a maximum time limit.

9. 1. A method of actuating an electronic spindle lock on a power tool including a motor configured to rotate a bit receiving portion, the method comprising: entering, with a controller of the power tool, an electronic spindle lock mode for controlling the motor to engage or disengage the bit-receiving portion with a tool bit; and initiating, with the controller, a spindle lock control loop in response to entering the electronic spindle lock mode, the spindle lock control loop comprising: Determining a position of the motor in a first direction; determining that the position amount differs from an expected position amount of the motor; and controlling the motor to generate a torque in a second direction, the torque maintaining a rotational position of the motor in response to determining that the position quantity differs from the expected position quantity of the motor. method.

10. determining that the power tool is stopped; initiating the spindle lock control loop in response to determining that the power tool is stopped; detecting, with one or more sensors, movement of the power tool after a delay time after activating the spindle lock control loop; entering a sleep mode when no motion of the power tool is detected after the delay time.

10. The method of claim 9.

11. determining when in the sleep mode that a wake-up signal is received; performing a normal motor operation when the wake-up signal is received from a trigger; initiating the spindle lock control loop when the wake-up signal is received from the one or more sensors, and the normal motor operation includes controlling the motor in accordance with a trigger pull of the trigger. The method of claim 10.

12. Determining that the position amount differs from the expected position amount of the motor includes: determining an expected rotor position of a rotor of the motor, the position quantity including an actual position of the rotor; determining a position error for the motor based on a difference between the predicted position of the rotor and the actual position of the rotor; determining an actual speed of the rotor of the motor; determining an expected speed of the rotor of the motor; determining a speed error for the motor based on a difference between the expected speed of the rotor and the actual speed of the rotor. The method of claim 10.

13. determining an expected current of the motor based on the difference between the expected speed of the rotor and the actual speed of the rotor; determining an actual amount of current in the motor; determining a current error for the motor based on a difference between the expected current in the motor and an actual amount of current in the motor. The method of claim 12.

14. Controlling the motor to rotate in the second direction in response to determining that the position amount of the motor differs from the expected position amount of the motor includes: generating a pulse width modulated (PWM) signal based on the current error for the motor; and controlling rotation of the motor based on the PWM signal. The method of claim 13.

15. Housing and A bit receiving portion provided on the housing; a motor within the housing configured to rotate the bit-receiving portion; a sensor configured to detect a position of the motor in a first direction; a controller coupled to the motor, the controller comprising: entering an electronic spindle lock mode for controlling the motor to engage or disengage the bit receiving portion with a tool bit; controlling the motor as a brake in response to entering the electronic spindle lock mode. wherein the motor generates a counter torque to maintain a rotational position of the motor in response to determining a difference between an expected position of the motor and the position of the motor in the first direction. Power tools.

16. Further comprising a trigger; The controller is further configured to enter the electronic spindle lock mode when the trigger is released to stop operation of the power tool, the electronic spindle lock mode preventing movement of a drive train when the bit receiving portion is rotated. The power tool according to claim 15.

17. 16. The power tool of claim 15, further comprising a metal oxide semiconductor field effect transistor (MOSFET) connected between motor windings of the motor.

18. a battery pack for providing operating power to the motor; the MOSFET is a depletion mode MOSFET; when the battery pack is removed, the depletion-mode MOSFET is normally closed; The controller is further configured to open the depletion mode MOSFET when the battery pack is connected to the power tool.

18. The power tool of claim 17.

19. 16. The power tool of claim 15, further comprising a battery pack providing operating power to the motor, the motor further comprising a secondary winding configured to reduce a voltage when the bit receiving portion is rotated relative to the housing and the battery pack is disconnected from the power tool.

20. 20. The power tool of claim 19, wherein the voltage to the secondary winding is used to charge a capacitor, and when the capacitor is fully charged, the capacitor is used to short out a motor winding of the motor.

Images