JP7296587B2 - Electric tool, control method and program - Google Patents

Description

TECHNICAL FIELD The present disclosure generally relates to an electric power tool, control method, and program, and more particularly to an electric power tool that controls a motor using vector control, an electric power tool control method, and a program.

Patent Literature 1 discloses a clamping tool that rotates an anvil by striking the anvil with a hammer.

A control board for the tightening tool described in Patent Document 1 incorporates a sound receiving section that receives the sound of collision between the hammer and the anvil. When the microcomputer attached to the control board drives the motor in the reverse direction, which is the direction in which nuts are loosened, the motor stops after a predetermined period of time after the collision between the hammer and the anvil is no longer detected by the sound receiving section. It controls the operation of the motor and the sound receiving section based on the control program. As a result, the motor automatically stops before the nuts are completely removed from the bolts or the like.

JP-A-2001-269874

In an electric power tool such as the tightening tool described in Patent Document 1, looseness of nuts or the like is detected by the collision sound between the hammer and the anvil. Therefore, depending on the environment in which the power tool is used, such as an environment in which the sound receiving section is difficult to receive the impact sound, it may be difficult to detect the looseness of the nuts, and there is room for improvement in usability.

The present disclosure has been made in view of the above reasons, and aims to improve usability of electric power tools.

A power tool according to an aspect of the present disclosure includes a motor, an operation section, a control section, an output shaft, and a transmission mechanism. The operation unit receives an operation from a user. The control section uses vector control to control the rotation of the motor according to the operation of the operation section. The output shaft is connected with the tip tool. The tip tool rotates the tightening member. The transmission mechanism transmits the rotational force of the motor to the output shaft. The transmission mechanism does not have an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft. The control section has a looseness detection function. In the loosening detection function, the control unit detects the tightening member based on the exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool. Detect loose parts. The control unit detects the looseness of the tightening member by detecting the peak in the opposite direction after detecting the peak of the excitation current. The controller reduces the speed of the motor or stops the motor when the looseness of the tightening member is detected.
A power tool according to an aspect of the present disclosure includes a motor, an operation section, a control section, an output shaft, and a transmission mechanism. The operation unit receives an operation from a user. The control section uses vector control to control the rotation of the motor according to the operation of the operation section. The output shaft is connected with the tip tool. The tip tool rotates the tightening member. The transmission mechanism transmits the rotational force of the motor to the output shaft. The transmission mechanism has an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft. The control section has a looseness detection function. In the loosening detection function, the control unit detects the tightening member based on the exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool. Detect loose parts. The control unit determines that the tightening member is loosened when the amplitude of the exciting current within a predetermined unit time changes from being equal to or greater than a threshold to being less than the threshold. The controller reduces the speed of the motor or stops the motor when the looseness of the tightening member is detected.

A control method according to an aspect of the present disclosure is a control method for a power tool. The power tool includes a motor, an operation section, an output shaft, and a transmission mechanism. The operation unit receives an operation from a user. The output shaft is connected with the tip tool. The tip tool rotates the tightening member. The transmission mechanism transmits the rotational force of the motor to the output shaft. The transmission mechanism does not have an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft. The control method includes using vector control to control the rotation of the motor according to the operation of the operation unit. The control method detects loosening of the tightening member based on an exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool. Including. Detecting the looseness of the tightening member includes detecting the looseness of the tightening member by detecting a reverse peak after detecting a peak of the excitation current. The control method includes slowing or stopping the motor upon detecting the loosening of the tightening member.
A control method according to an aspect of the present disclosure is a control method for a power tool. The power tool includes a motor, an operation section, an output shaft, and a transmission mechanism. The operation unit receives an operation from a user. The output shaft is connected with the tip tool. The tip tool rotates the tightening member. The transmission mechanism transmits the rotational force of the motor to the output shaft. The transmission mechanism has an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft. The control method includes using vector control to control the rotation of the motor according to the operation of the operation unit. The control method detects loosening of the tightening member based on an exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool. Including. In detecting the loosening of the tightening member, it is determined that the tightening member is loosened when the amplitude of the excitation current within a predetermined unit time changes from being equal to or greater than a threshold to being below the threshold. including doing The control method includes slowing or stopping the motor upon detecting the loosening of the tightening member.

A program according to one aspect of the present disclosure is a program for causing one or more processors to execute the control method.

According to the present disclosure, there is an advantage that the usability of the power tool can be improved.

FIG. 1 is a block diagram of a power tool according to one embodiment. FIG. 2 is a schematic diagram of the power tool same as the above. FIG. 3 is an explanatory diagram of vector control by the control unit of the electric power tool. FIG. 4 is a graph showing an operation example of the power tool. FIG. 5 is a flow chart showing a control method for the electric power tool. FIG. 6 is a graph showing an operation example of the power tool according to the modification.

A power tool 1 according to an embodiment will be described below with reference to the drawings. However, the embodiment described below is but one of the various embodiments of the present disclosure. The embodiments described below can be modified in various ways according to design and the like as long as the objects of the present disclosure can be achieved. Each drawing described in the following embodiments is a schematic drawing, and the ratio of the size and thickness of each component in the drawing does not necessarily reflect the actual dimensional ratio. .

(1) Outline As shown in FIGS. 1 and 2 , the power tool 1 includes a motor 15 , an operation section 29 , a control section 4 , an output shaft 21 and a transmission mechanism 18 .

The operation unit 29 receives operations from the user. The control unit 4 uses vector control to control the rotational operation of the motor 15 according to the operation of the operation unit 29 . The output shaft 21 is connected with a tip tool 28 that rotates the tightening member 30 . The transmission mechanism 18 transmits the torque of the motor 15 to the output shaft 21 . The tightening member 30 is a member that is tightened against the object 100 . The tightening member 30 is, for example, a bolt, nut, screw (such as a wood screw), Torx (registered trademark), or the like. The tip tool 28 is, for example, a socket bit, a wrench bit, a driver bit, a torx bit, or the like. The object 100 is, for example, a piece of wood, a wall, a bolt for a nut, or the like.

The control unit 4 has a looseness detection function. The looseness detection function detects looseness of the fastening member 30 based on the exciting current (d-axis current) when the fastening member 30 fastened to the workpiece 100 is loosened from the workpiece 100 by the tip tool 28. It is a function. When the looseness of the tightening member 30 is detected by the looseness detection function, the controller 4 reduces the speed of the motor 15 or stops the motor 15 .

The looseness detection function of the power tool 1 detects looseness of the tightening member 30 from the object 100 based on the exciting current supplied to the motor 15 . Therefore, according to the power tool 1 of the present embodiment, the reliability of detecting looseness of the tightening member 30 such as a screw can be improved, and the usability of the power tool 1 can be improved.

The value of the exciting current is also used for vector control of the motor 15 . Therefore, there is no need to newly add a looseness detection sensor or the like, and the size and cost of the power tool 1 can be reduced.

(2) Details (2.1) Power tool Hereinafter, the power tool 1 of the present embodiment will be described in more detail with reference to the drawings. The power tool 1 of this embodiment is a so-called impact tool. Impact tools are used, for example, as impact drivers, hammer drills, impact drills, impact drill drivers or impact wrenches. In this embodiment, as a typical example, a case where the power tool 1 is used as an impact driver will be described.

As shown in FIGS. 1 and 2, the electric power tool 1 includes a motor 15, an output shaft 21, a transmission mechanism 18, a socket 23, a tip tool 28, a power supply section 32, an operation section 29, and a control section. 4 , an inverter circuit section 51 , and a forward/reverse switch 9 .

Motor 15 is a brushless motor. In particular, the motor 15 of this embodiment is a synchronous motor, more specifically, a permanent magnet synchronous motor (PMSM). Motor 15 includes a rotor 13 having permanent magnets 131 and a stator 14 having coils 141 . The rotor 13 has a rotating shaft 16 that outputs rotational power. Electromagnetic interaction between the coils 141 and the permanent magnets 131 causes the rotor 13 to rotate with respect to the stator 14 .

The output shaft 21 is a portion rotated by driving force transmitted from the motor 15 via the transmission mechanism 18 . The socket 23 is fixed to the output shaft 21 . A tip tool 28 is detachably attached to the socket 23 . The tip tool 28 rotates together with the output shaft 21 . The power tool 1 rotates the tip tool 28 by rotating the output shaft 21 with the driving force of the motor 15 . In other words, the power tool 1 is a tool that drives the tip tool 28 with the driving force of the motor 15 . Among various kinds of tip tools 28, the tip tool 28 corresponding to the application is attached to the socket 23 and used. Note that the tip tool 28 may be attached directly to the output shaft 21 . With the tip tool 28 in contact with the fastening member 30 (bolt, screw, etc.), the fastening member 30 can be fastened to the object 100 by rotating the tip tool 28 in the normal direction. In addition, while the tip tool 28 is in contact with the tightening member 30 (bolt, screw, etc.), the tip tool 28 rotates in the reverse direction (opposite direction to the normal rotation direction), thereby rotating the tightening member 30 as a target. The object 100 can be loosened.

The power tool 1 of the present embodiment includes the socket 23 so that the tip tool 28 can be replaced depending on the application, but it is not essential that the tip tool 28 is replaceable. For example, the power tool 1 may be a tool that can use only a specific tip tool 28 .

The tip tool 28 of this embodiment is a driver bit for tightening or loosening the tightening member 30 (screw). More specifically, the tip tool 28 is a Phillips screwdriver bit with a tip portion 280 formed in a + (plus) shape. That is, the output shaft 21 holds a driver bit for tightening or loosening screws and is powered by the motor 15 to rotate.

The transmission mechanism 18 has an impact mechanism 17 , a planetary gear mechanism 25 and a drive shaft 22 . The transmission mechanism 18 transmits the rotational power of the rotary shaft 16 of the motor 15 to the output shaft 21 . More specifically, the transmission mechanism 18 adjusts the rotational power of the rotating shaft 16 of the motor 15 and outputs it as rotation of the output shaft 21 .

A rotating shaft 16 of the motor 15 is connected to a planetary gear mechanism 25 . The drive shaft 22 is connected to the planetary gear mechanism 25 and the impact mechanism 17 . The planetary gear mechanism 25 reduces the rotational power of the rotating shaft 16 of the motor 15 at a predetermined reduction ratio, and outputs it as rotation of the drive shaft 22 .

The impact mechanism 17 is connected with the output shaft 21 . The impact mechanism 17 transmits the rotational power of the motor 15 (rotating shaft 16 ) received via the planetary gear mechanism 25 and the drive shaft 22 to the output shaft 21 .

The impact mechanism 17 performs an impact operation according to the magnitude of torque applied to the output shaft 21 . The impact mechanism 17 applies impact force to the output shaft 21 in the impact operation.

As shown in FIG. 2, the impact mechanism 17 includes a hammer 19, an anvil 20, and a spring 24. As shown in FIG. The hammer 19 is attached to the drive shaft 22 via a cam mechanism. The anvil 20 is in contact with the hammer 19 and rotates together with the hammer 19 . A spring 24 pushes the hammer 19 toward the anvil 20 . Anvil 20 is formed integrally with output shaft 21 . The anvil 20 may be formed separately from the output shaft 21 and fixed to the output shaft 21 .

When the load (torque) applied to the output shaft 21 is smaller than a predetermined magnitude, the impact mechanism 17 continuously rotates the output shaft 21 by the rotational power of the motor 15 . That is, in this case, the drive shaft 22 and the hammer 19 connected by the cam mechanism rotate together, and furthermore, the hammer 19 and the anvil 20 rotate together. 21 rotates together with the drive shaft 22 .

On the other hand, when the output shaft 21 is subjected to a load of a predetermined magnitude or more, the impact mechanism 17 performs an impact operation. The impact mechanism 17 converts the rotational power of the motor 15 into pulsed torque to generate an impact force in the impact operation. That is, in the striking operation, the hammer 19 retreats (separates from the anvil 20) against the spring 24 while being regulated by the cam mechanism between it and the drive shaft 22. When the hammer 19 retreats and the coupling between the hammer 19 and the anvil 20 is released, the hammer 19 moves forward while rotating (moves to the output shaft 21 side) and applies a rotational impact force to the anvil 20, thereby outputting an output. Axis 21 is rotated. That is, the impact mechanism 17 applies a rotational impact around the shaft (output shaft 21 ) to the output shaft 21 via the anvil 20 . In the striking operation of the impact mechanism 17, the hammer 19 repeatedly applies an impact force to the anvil 20 in the rotational direction. Each time the hammer 19 moves backward and forward, one impact force is generated.

The power supply unit 32 supplies current for driving the motor 15 . The power supply unit 32 is, for example, a battery pack. The power supply unit 32 includes, for example, one or more secondary batteries.

The operation unit 29 has a trigger switch. By pulling the trigger switch, the motor 15 can be turned on and off. In addition, the rotation speed of the motor can be adjusted by the amount of pull when the trigger switch is pulled. As a result, it is possible to adjust the rotation speed of the output shaft 21 by the amount of retraction of the operation of pulling the trigger switch. As the retraction amount increases, the rotational speeds of the motor 15 and the output shaft 21 increase. The control unit 4 rotates or stops the motor 15 and the output shaft 21 and controls the rotation speeds of the motor 15 and the output shaft 21 according to the amount of pull of the operation of pulling the trigger switch. In this electric power tool 1 , the tip tool 28 is connected to the output shaft 21 through the socket 23 . The rotation speed of the tip tool 28 is controlled by controlling the rotation speed of the motor 15 and the output shaft 21 by operating the trigger switch.

More specifically, the trigger switch includes a multistep switch or stepless switch (variable resistor) that outputs an operation signal. The operation signal changes according to the amount of operation (pull-in amount) to the trigger switch. The trigger switch determines a target value ω ₁ ^* of the speed (rotational speed) of the motor 15 according to the operation signal and gives it to the control unit 4 . The control unit 4 controls rotation of the motor 15 based on the target value ω ₁ ^* received from the trigger switch.

The forward/reverse selector switch 9 switches the rotation direction of the output shaft 21 between the forward rotation direction and the reverse rotation direction opposite to the forward rotation direction. The forward rotation direction is the direction in which the fastening member 30 is fastened to the object 100 (the direction in which the fastening member 30 rotates clockwise when viewed from the head side of the fastening member 30). The reverse direction is the direction in which the fastening member 30 is loosened from the object 100 (the direction in which the fastening member 30 rotates counterclockwise when viewed from the head side of the fastening member 30).

The forward/reverse selector switch 9 switches the direction of rotation of the rotating shaft 16 of the motor 15 here. The forward/reverse selector switch 9 switches the direction of current supplied from the power source 32 to the motor 15, for example, to switch the rotation direction of the rotating shaft 16 of the motor 15 between forward and reverse.

The inverter circuit section 51 is a circuit for driving the motor 15 . The inverter circuit section 51 converts the voltage _Vdc from the power supply section 32 into the drive voltage _Va for the motor 15 . In this embodiment, the drive voltage _Va is a three-phase AC voltage including a U-phase voltage, a V-phase voltage and a W-phase voltage. Hereinafter, the U-phase voltage is represented by v _u , the V-phase voltage by v _v , and the W-phase voltage by v _w as necessary. Each voltage v _u , v _v , v _w is a sinusoidal voltage.

The inverter circuit section 51 can be realized using a PWM inverter and a PWM converter. The PWM converter generates pulses according to target values (voltage command values) v _u ^* , v v *, ^v _w ^* of drive voltages V _a (U-phase voltage v _u , V-phase voltage _{v v} , W-phase voltage v _w ). Generate a width modulated PWM signal. The PWM inverter drives the motor 15 by applying a driving voltage V _a (v _u , v _v , v _w ) corresponding to the PWM signal to the motor 15 . More specifically, the PWM inverter includes three-phase half-bridge circuits and drivers. In the PWM inverter, the driver ^turns on/off the switching elements in ^each _half -bridge circuit in accordance with the _PWM signal, so that the drive voltage _{V a} ⁽ v _u , _{v v 1} , v _w ) are provided to the motor 15 . As a result, the motor 15 is supplied with a drive current corresponding to the drive voltage V _a (v _u , v _v , v _w ). The drive currents include U-phase current i _u , V-phase current i _v , and W-phase current i _w . More specifically, the U-phase current i _u , the V-phase current i _v , and the W-phase current i _w are the current of the U-phase armature winding, the V-phase armature winding, and and the current of the W-phase armature winding.

The controller 4 obtains a speed command value ω ₂ ^* of the motor 15 . In particular, the control unit 4 obtains the command value ω ₂ ^* for the speed of the motor 15 based on the target value ω ₁ ^* for the speed of the motor 15 given from the operation unit 29 . Further, the control unit 4 determines _target values (voltage command values) _vu ^* , _vv ^* , _vw ^* of the drive voltage Va such that the speed of the motor 15 matches the command value _ω2 ^* , and controls the inverter. It is applied to the circuit section 51 .

(2.2) Control Unit Hereinafter, the control unit 4 will be described in further detail. The control unit 4 controls the motor 15 using vector control in this embodiment. Vector control is a motor control method that separates the motor current into a current component that generates torque (rotational force) (torque current) and a current component that generates magnetic flux (excitation current), and controls each current component independently. is a kind of

FIG. 3 is an analysis model diagram of the motor 15 in vector control. FIG. 3 shows U-phase, V-phase, and W-phase armature winding fixed shafts. Vector control considers a rotating coordinate system that rotates at the same speed as the magnetic flux generated by the permanent magnet 131 provided in the rotor 13 of the motor 15 . In the rotating coordinate system, the direction of the magnetic flux generated by the permanent magnet 131 is taken as the d-axis, and the rotation axis for control corresponding to the d-axis is taken as the γ-axis. Also, the q-axis is taken at a phase leading 90 electrical degrees from the d-axis, and the δ-axis is taken at a phase leading 90 electrical degrees from the γ-axis. A rotating coordinate system corresponding to the real axes is a coordinate system in which the d-axis and the q-axis are selected as coordinate axes, and the coordinate axes are called dq-axes. A rotating coordinate system for control is a coordinate system in which the γ-axis and the δ-axis are selected as coordinate axes, and the coordinate axes are called γδ-axes.

The dq-axes are rotating and their rotational speed is represented by ω. The γδ axis is also rotating, and its rotational speed is represented by _ωe . In the dq-axis, the angle (phase) of the d-axis viewed from the U-phase armature winding fixed axis is represented by θ. Similarly, on the γδ-axis, the angle (phase) of the γ-axis viewed from the U-phase armature winding fixed axis is represented by _θe . The angles denoted by θ and θ _e are angles in electrical degrees, and they are also commonly referred to as rotor positions or magnetic pole positions. The rotational velocities represented by ω and ω _e are angular velocities in electrical angles. Hereinafter, θ or _θe may be referred to as the rotor position, and ω or _ωe may simply be referred to as the speed, as required.

The control unit 4 basically performs vector control so that θ and _θe match. When θ and _θe match, the d-axis and q-axis match the γ-axis and δ-axis, respectively. In the following description, the γ-axis component and the δ-axis component of the drive voltage _Va are represented by the γ-axis voltage _vγ and the δ-axis voltage _vδ , respectively, and the γ-axis component and the δ-axis component of the drive current The components are denoted by γ-axis current i _γ and δ-axis current i _δ , respectively.

Also, the voltage command values representing the target values of the γ-axis voltage v _γ and the δ-axis voltage v _δ are represented by the γ-axis voltage command value v _γ ^* and the δ-axis voltage command value v _δ ^* , respectively. Current command values representing the target values of the γ-axis current i _γ and the δ-axis current i _δ are represented by the γ-axis current command value i _γ ^* and the δ-axis current command value i _δ ^* , respectively.

The control unit 4 causes the values of the γ-axis voltage v _γ and the δ-axis voltage v _δ to follow the γ-axis voltage command value v _γ ^* and the δ-axis voltage command value v _δ ^* , respectively, and the γ-axis current i _γ and the δ-axis current Vector control is performed such that the value of i _δ follows the γ-axis current command value i _γ ^* and the δ-axis current command value i _δ ^* , respectively.

Control unit 4 includes a computer system having one or more processors and memory. At least part of the functions of the control unit 4 are realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in memory, may be provided through an electric communication line such as the Internet, or may be recorded and provided in a non-temporary recording medium such as a memory card.

As shown in FIG. 1, the control unit 4 includes coordinate converters 411, 412, subtractors 421, 422, 423, a current control unit 43, a magnetic flux control unit 44, a speed control unit 45, a position/speed An estimation unit 46 , a step-out detection unit 47 , and a command value generation unit 48 are provided. Note that the coordinate converter 411, the subtractors 421, 422, 423, the current controller 43, the magnetic flux controller 44, the speed controller 45, the position/speed estimator 46, the step-out detector 47, and the command value generator 48 are , does not necessarily indicate a tangible composition. These indicate functions realized by the control unit 4 . Therefore, each element of the control unit 4 can freely use each value generated within the control unit 4 . The power tool 1 also includes a plurality of (two in FIG. 1) current sensors 61 and 62 .

Each of the plurality of current sensors 61, 62 includes, for example, a Hall element current sensor or a shunt resistance element. A plurality of current sensors 61 and 62 measure the current supplied from the power supply section 32 to the motor 15 via the inverter circuit section 51 . A plurality of current sensors 61 and 62 measure at least two phase currents. In FIG. 1, current sensor 61 measures U-phase current i _u and current sensor 62 measures V-phase current _iv . The W-phase current _iw can be obtained from the U-phase current _iu and the V-phase current _iv .

A coordinate converter (first coordinate converter) 411 converts the U-phase current _iu and the V-phase current _iv onto the γδ-axis based on the rotor position _θe , thereby converting the γ-axis currents _iγ and δ-axis current i _δ is calculated and output. Here, the γ-axis current i _γ corresponds to the d-axis current, is an exciting current, and is a current that hardly contributes to the torque. The δ-axis current i _δ is a current that corresponds to the q-axis current and greatly contributes to the torque. The rotor position θ _e is calculated by the position/speed estimator 46 .

The subtractor 423 refers to the speed ω _e and the command value ω ₂ ^* to calculate the speed deviation (ω ₂ ^* - ω _e ) between them. The velocity ω _e is calculated by the position/velocity estimator 46 .

The speed control unit 45 uses proportional integral control or the like to calculate and output the δ-axis current command value i _δ ^* so that the speed deviation (ω ₂ ^* - ω _e ) converges to zero.

The magnetic flux control unit 44 determines the γ-axis current command value i _γ ^* and outputs it to the subtractor 421 . The γ-axis current command value i _γ ^* can take various values depending on the type of vector control executed by the control unit 4 and the speed ω of the motor 15 . For example, when maximum torque control is performed with the d-axis current set to zero, the γ-axis current command value i _γ ^* is set to zero. Further, when the flux-weakening control is performed by passing the d-axis current, the γ-axis current command value i _γ ^* is set to a negative value corresponding to the speed ω _e . The following description deals with the case where the γ-axis current command value i _γ ^* is zero.

The subtractor 421 subtracts the _γ -axis current i γ output from the coordinate converter 411 from the γ-axis current command value i _γ ^* output from the magnetic flux control unit 44 to obtain a current error (i _γ ^* −i _γ ). calculate. A subtractor 422 subtracts the δ-axis current i _δ output from the coordinate converter 411 from the value i _δ ^* output from the speed control unit 45 to calculate a current error (i _δ ^* −i _δ ).

The current control unit 43 performs current feedback control using proportional integral control or the like so that both the current errors (i _γ ^* −i _γ ) and (i _δ ^* −i _δ ) converge to zero. At this time, non-interference control is used to eliminate interference between the γ-axis and the δ-axis so that (i _γ ^* -i _γ ) and (i _δ ^* -i _δ ) both converge to zero. γ-axis voltage command value v _γ ^* and δ-axis voltage command value v _δ ^* are calculated.

A coordinate converter (second coordinate _{converter) 412 converts γ-axis voltage command values v γ *} ^and δ The voltage command values (v _u ^* , v _v ^* and v _w ^* ) are calculated and output by coordinate-transforming the shaft voltage command values v _δ ^* onto three-phase fixed coordinate axes.

A position/speed estimator 46 estimates the rotor position θ _e and speed ω _e . More specifically, the position/velocity estimation unit 46 uses all or part of i _γ and i _δ from the coordinate converter 411 and v _γ ^* and v _δ ^* from the current control unit 43 to calculate the proportional Perform integral control, etc. The position/speed estimator 46 estimates the rotor position θ _e and the rotor speed ω _e such that the axis error (θ _e −θ) between the d-axis and the γ-axis converges to zero. Various methods have been conventionally proposed as methods for estimating the rotor position θ _e and the rotor speed ω _e , and the position/speed estimator 46 can employ any known method.

The out-of-step detector 47 determines whether the motor 15 is out of step. More specifically, the step-out detector 47 determines whether the motor 15 is out of step based on the magnetic flux of the motor 15 . The magnetic flux of the motor 15 is obtained from the d-axis current, the q-axis current, the γ-axis voltage command value v _γ ^* , and the δ-axis voltage command value v _δ ^* . The step-out detector 47 may determine that the motor 15 is out of step if the amplitude of the magnetic flux of the motor 15 is less than the threshold. Note that the threshold is appropriately determined based on the amplitude of the magnetic flux produced by the permanent magnet of the motor 15 . Various methods have been conventionally proposed as a method for detecting a step-out, and the step-out detection unit 47 can employ any known method.

The command value generator 48 is a part of the controller 4 that obtains the command value ω ₂ ^* of the speed of the motor 15 . The command value generator 48 obtains the command value ω ₂ ^* based on the target value ω ₁ ^* received from the operation unit 29 .

The command value generator 48 has a normal mode and a low speed mode as operation modes.

In the normal mode, the command value generator 48 sets the target value ω ₁ ^* received from the operation unit 29 as the command value ω ₂ ^* . In normal mode, the command value ω ₂ ^* matches the target value ω ₁ ^* .

In the low speed mode, the command value generator 48 determines the command value ω ₂ ^* based on the target value ω ₁ ^* and a predetermined upper limit value. In the low speed mode, the command value generator 48 uses the target value ω ₁ ^* as the command value ω ₂ ^* when the received target value ω ₁ ^* is smaller than the upper limit value. On the other hand, when the target value ω ₁ ^* is greater than or equal to the upper limit, the command value generator 48 uses the upper limit as the command value ω ₂ ^* . In short, the command value generator 48 limits the command value ω ₂ ^* to the upper limit value or less in the low speed mode. Therefore, in the low speed mode, the speed (angular speed) of the motor 15 is limited to the upper limit value or less.

The command value generator 48 sets the operation mode based on the rotation direction of the output shaft 21 set by the forward/reverse selector switch 9 .

That is, the command value generator 48 operates in the normal mode when the forward/reverse selector switch 9 sets the rotation direction of the output shaft 21 to the forward rotation direction.

On the other hand, when the direction of rotation of the output shaft 21 is set to the reverse direction by the forward/reverse selector switch 9, the command value generator 48 selects the operation mode based on the result of detection by the looseness detection function described below. switch. Specifically, the command value generator 48 operates in the normal mode before detecting looseness of the tightening member 30 by the looseness detection function, and shifts to the low speed mode when looseness of the tightening member 30 is detected. In other words, before detecting the loosening of the tightening member 30, the control unit 4 controls the operation of the motor 15 according to the operation amount of the operation unit 29 (trigger switch) to detect the loosening of the tightening member 30. Then, the speed of the motor 15 is limited to a predetermined upper limit or less. The control unit 4 of the present embodiment enables the looseness detection function only when the direction of rotation of the tip tool 28 is set to the reverse direction by the normal/reverse selector switch 9 .

The looseness detection function is a function of detecting that the tightening member 30 to be worked on has been loosened from the object 100 when the rotation direction of the output shaft 21 is set to the reverse direction.

Based on at least one of the δ-axis current i _δ (that is, torque current) and γ-axis current i _γ (that is, excitation current) obtained by the coordinate converter 411, the control unit 4 adjusts the tightening member 30 from the object 100 can be detected. The control unit 4 of the present embodiment detects loosening of the tightening member 30 from the object 100, particularly based on the γ-axis current i _γ (excitation current).

FIG. 4 schematically shows changes in the δ-axis current i _δ (torque current) and the γ-axis current i _γ (excitation current) when the fastening member 30 is loosened from the object 100 by the power tool 1 . In FIG. 4, the motor 15 starts operating at time t0, and the impact mechanism 17 starts impacting at time t1. Also, at time t2, the tightening member 30 is loosened and the load applied to the output shaft 21 is reduced, so that the impact mechanism 17 finishes the striking operation.

In the period (time t1 to t2) before the tightening member 30 is loosened, the striking operation by the impact mechanism ₁₇ is seen as a current value oscillation as shown in FIG. appear. Specifically, in the striking operation of the impact mechanism 17, the load applied to the rotary shaft 16 of the motor 15 gradually increases while the hammer 19 moves backward. When the hammer 19 and the anvil 20 are disconnected, the load applied to the rotating shaft 16 of the motor 15 is reduced. As described above, the control unit 4 performs control so that the rotor position θ on the dq axes and the rotor position _θe on the γδ axes match. Therefore, when the load applied to the rotating shaft 16 of the motor 15 increases _or decreases, the control unit 4 performs control so as to compensate for the difference between θ and _θe caused by this increase or decrease. increases or decreases. Specifically, immediately after the load applied to the motor 15 becomes small, the measured value of the γ-axis current i _γ increases and becomes a positive value. The measured value of _γ decreases to a negative value.

The control unit 4 of the present embodiment detects the start and end of the striking operation of the impact mechanism 17 by detecting the start and end of oscillation of the γ-axis current i _γ (excitation current). Then, the control unit 4 indirectly detects the looseness of the tightening member 30 when the impact mechanism 17 finishes the striking operation. In short, the control unit 4 detects looseness of the tightening member 30 based on the amplitude of the excitation current in the looseness detection function. More specifically, in the looseness detection function, the control unit 4 detects the amplitude of the γ-axis current i _γ (for example, 1/2 of the difference between the maximum value and the minimum value within a predetermined unit time) and a predetermined threshold value. comparison. When the amplitude of the γ-axis current i _γ changes from the threshold value or more to below the threshold value, it is determined that the tightening member 30 has loosened.

Further, as shown in FIG. 4, from time t0 to t1, a load is applied to the output shaft 21, so that the torque applied to the rotating shaft 16 of the motor 15 increases and the δ-axis current i _δ increases. Then, when the tightening member 30 is loosened from the object 100 at time t2, the load (torque) applied to the output shaft 21 is reduced, thereby reducing the δ-axis current i _δ (torque current).

Therefore, the control unit 4, for example, compares the δ-axis current i _δ with the threshold Th1, and detects that the absolute value of the δ-axis current i _δ once exceeds the threshold Th1 and then falls below the threshold Th1. , it is possible to detect looseness of the tightening member 30 .

Furthermore, in the period before the tightening member 30 is loosened (time points t1 to t2), the striking operation by the impact mechanism ₁₇ has a current value as shown in FIG. Appears as vibration. Specifically, the measured value of the δ-axis current i _δ decreases immediately after the load applied to the motor 15 becomes small, and the measured value of the δ-axis current i _δ decreases immediately after the load applied to the motor 15 increases. To increase.

Therefore, the control unit 4 detects the end of the impact operation of the impact mechanism 17 by detecting the end of oscillation of the δ-axis current i _δ (torque current), and based on this, loosens the tightening member 30. Indirect detection is also possible.

In short, the control unit 4 may detect looseness of the tightening member 30 further based on the torque current supplied to the motor 15 in the looseness detection function.

The control unit 4 may detect looseness of the tightening member 30 based on the logical sum of the detection result based on the exciting current and the detection result based on the torque current, or may detect the looseness of the tightening member 30 based on the logical product. Looseness may be detected.

As described above, the command value generator 48 shifts from the normal mode to the low speed mode when the looseness of the tightening member 30 is detected by the looseness detection function. Accordingly, when looseness of the tightening member 30 is detected, the speed of the motor 15 is limited to the upper limit value or less. Therefore, when the clamping member 30 is loosened, the motor 15 slows down before the clamping member 30 is completely removed from the object 100 . Therefore, it is possible to prevent a situation in which the fastening member 30 falls off from the object 100 and, for example, the fastening member 30 is lost. Note that the control unit 4 may stop the motor 15 when looseness of the tightening member 30 is detected. In this case, the occurrence of situations such as loss of the tightening member 30 can be further suppressed.

(3) Modifications Embodiments of the present disclosure are not limited to the above embodiments. The above-described embodiment can be modified in various ways according to design and the like, as long as the object of the present disclosure can be achieved. Modifications of the above embodiment are listed below.

A function similar to that of the control unit 4 of the power tool 1 may be embodied by a control method of the power tool 1, a (computer) program, or a non-temporary recording medium recording the program.

A method of controlling the electric power tool 1 according to one aspect includes controlling the rotational operation of the motor 15 according to the operation of the operation unit 29 using vector control. Further, the control method is such that when the fastening member 30 fastened to the object 100 is loosened from the object 100 by the tip tool 28, the loosening of the fastening member 30 is controlled based on the exciting current supplied to the motor 15. Including detecting. The control method also includes reducing the speed of the motor 15 or stopping the motor 15 upon detecting loosening of the tightening member 30 .

Specifically, as shown in FIG. 5, the controller 4 first determines whether or not the rotation direction of the motor 15 is set to the forward rotation direction (ST1).

When the rotation direction of the motor 15 is the forward rotation direction (ST1: Yes), the control unit 4 performs vector control of the motor 15 using the command value ω ₂ ^* set according to the operation amount of the operation unit 29 ( ST6).

When the rotation direction of the motor 15 is the reverse direction (ST1: No), the control unit 4 vector-controls the motor 15 according to the operation amount of the operation unit 29 (ST2), and determines the excitation current used in the vector control. (Comparison of the amplitude of the excitation current and the threshold value) is performed (ST3). The control unit 4 determines whether looseness of the tightening member 30 is detected based on the determination result in step ST3 (ST4). When looseness is detected (ST4: Yes), the control unit 4 sets the command value ω ₂ ^* based on the upper limit to decelerate or stop the motor 15 (ST5).

A program according to one aspect is a program for causing one or more processors to execute the control method for the power tool 1 described above.

The execution subject of the control unit 4 described above includes a computer system. A computer system is mainly composed of a processor and a memory as hardware. Part of the function of the control unit 4 in the present disclosure is realized by the processor executing a program recorded in the memory of the computer system. The program may be recorded in advance in the memory of the computer system, may be provided through an electric communication line, or may be recorded in a non-temporary recording medium such as a computer system-readable memory card, optical disk, or hard disk drive. may be provided. A processor in a computer system consists of one or more electronic circuits, including semiconductor integrated circuits (ICs) or large scale integrated circuits (LSIs). The integrated circuit such as IC or LSI referred to here is called differently depending on the degree of integration, and includes integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). In addition, a field-programmable gate array (FPGA) that is programmed after the LSI is manufactured, or a logic device capable of reconfiguring the bonding relationship inside the LSI or reconfiguring the circuit partitions inside the LSI may also be adopted as the processor. can be done. A plurality of electronic circuits may be integrated into one chip, or may be distributed over a plurality of chips. A plurality of chips may be integrated in one device, or may be distributed in a plurality of devices. A computer system, as used herein, includes a microcontroller having one or more processors and one or more memories. Accordingly, the microcontroller also consists of one or more electronic circuits including semiconductor integrated circuits or large scale integrated circuits.

Moreover, it is not an essential configuration that the plurality of functions of the control unit 4 are integrated in one housing. The constituent elements of the control unit 4 may be distributed over a plurality of housings. Conversely, multiple functions of the control unit 4 may be integrated in one housing as in the basic example. Furthermore, at least part of the functions of the control unit 4 may be realized by a cloud (cloud computing) or the like.

(3-1) Modification 1
A power tool 1 according to Modification 1 will be described below. In the power tool 1 of this modified example, the same reference numerals are given to the same configurations as in the embodiment, and the description thereof is omitted.

The power tool 1 of this modification differs from the power tool 1 of the embodiment in that the transmission mechanism 18 does not include the impact mechanism 17 and, for example, the drive shaft 22 and the output shaft 21 are integrally coupled. . The power tool 1 of this modified example is, for example, a drill driver.

FIG. 6 shows changes in the δ-axis current i _δ (torque current) and the γ-axis current i _γ (excitation current) when the tightening member 30 is loosened from the object 100 by the power tool 1 of this modified example. .

In FIG. 6, the motor 15 starts operating at time t0. At time t1, a difference occurs between the rotor position θ on the dq axis and the rotor position _θe on the γδ axis. Peaks (extreme points in the current waveform) occur in i _δ and γ-axis current i _γ .

Further, when the fastening member 30 is loosened at time t2, a difference occurs between the rotor position θ on the dq axis and the rotor position _θe on the γδ axis, and the control unit 4 performs control to compensate for this difference. By doing so, a peak occurs in the γ-axis current _iγ . The control unit 4 detects the looseness of the fastening member 30 by detecting the occurrence of the peak of the γ-axis current _iγ based on the comparison between the γ-axis current _iγ and a predetermined threshold value.

As in the power tool 1 of this modified example, even in the power tool 1 other than the impact tool, the control unit 4 can detect looseness of the tightening member 30 based on the excitation current supplied to the motor 15. .

Note that the control unit 4 detects that the δ-axis current i _δ (torque current) has become smaller than the threshold value Th1 at time t3, thereby detecting loosening of the tightening member 30 further based on the torque current. is also possible.

The control unit 4 may detect looseness of the tightening member 30 based on the logical sum of the detection result based on the exciting current and the detection result based on the torque current, or may detect the looseness of the tightening member 30 based on the logical product. Looseness may be detected.

(3-2) Modification 2
The power tool 1 according to Modification 2 will be described below. In the power tool 1 of this modified example, the same reference numerals are given to the same configurations as in the embodiment, and the description thereof is omitted.

When the control unit 4 detects loosening of the tightening member 30, in addition to setting an upper limit value to the command value ω ₂ ^* of the speed of the motor 15, the command value ω ₂ ^* of the speed of the motor 15 is set to Decrease from the command value ω ₂ ^* before detection. That is, when the control unit 4 detects looseness of the tightening member 30, it reduces the speed of the motor 15 based on the speed before the looseness is detected.

For example, when detecting looseness of the tightening member 30, the control unit 4 multiplies the command value ω ₂ ^* at the time of detecting the looseness by a predetermined positive value smaller than 1 (for example, 0.8). may be used as the new command value ω ₂ ^* . Alternatively, when the control unit 4 detects loosening of the tightening member 30, the control unit 4 subtracts a predetermined value (for example, 2000 [rpm]) from the command value ω ₂ ^* at the time when the loosening is detected, and uses it as a new command value. ω ₂ ^* may be used. However, the control unit 4 appropriately adjusts the predetermined value so that the command value ω ₂ ^* is equal to or greater than zero.

Further, the control unit 4 may set the speed of the motor 15 to a predetermined value when looseness of the tightening member 30 is detected. That is, when the control unit 4 detects looseness of the tightening member 30, the command value ω ₂ ^* may be set to a predetermined value, thereby setting the speed of the motor 15 to a predetermined speed.

According to this modified example, even when the amount of retraction of the trigger switch is relatively small (when the command value ω ₂ ^* is smaller than the upper limit value), the command value ω ₂ ^* and the speed of the motor 15 can be decreased.

(3-3) Modification 3
A power tool 1 according to Modification 3 will be described below. In the power tool 1 of this modified example, the same reference numerals are given to the same configurations as in the embodiment, and the description thereof is omitted.

The control unit 4 controls the speed of the motor 15 to a predetermined speed regardless of the pull amount of the trigger switch. For example, the control unit 4 sets the command value ω ₂ ^* of the speed of the motor 15 to the first value after the trigger switch is pulled and the motor 15 is started until the looseness of the tightening member 30 is detected. do. Further, for example, when looseness of the tightening member 30 is detected, the control unit 4 sets the command value ω ₂ ^* to a second value (<first value). When the user stops pulling the trigger switch, the controller 4 sets the command value ω ₂ ^* to 0 [rpm].

According to the power tool 1 of this modified example, the speed of the motor 15 can be controlled regardless of the user's proficiency level.

(3-4) Other Modifications In one modification, the power tool 1 may not include the forward/reverse selector switch 9 . In this case, the power tool 1 may be fixed such that the rotation direction of the output shaft 21 is reversed (the direction in which the tightening member 30 is loosened).

In a modified example, the normal/reverse selector switch 9 may be configured to switch the rotation direction of the output shaft 21 using a mechanism within the transmission mechanism 18 . That is, the direction of rotation of the motor 15 and the direction of rotation of the output shaft 21 may be switched between the same direction and the opposite direction by operating the forward/reverse selector switch 9 .

In a modified example, the control unit 4 may enable the looseness detection function even when the rotation direction of the output shaft 21 is set to the forward rotation direction by the forward/reverse selector switch 9 . For example, it can be used when loosening a reverse screw (left-hand screw), or when an adapter for reversing the direction of rotation is provided between the tip tool 28 and the clamping member 30, or the like.

In a modified example, the power tool 1 may include a switching section that switches between enabling and disabling the looseness detection function. The switching unit may include, for example, a switch that receives a user's operation.

(4) Aspects The following aspects are disclosed from the above-described embodiments, modifications, and the like.

A power tool (1) of a first aspect includes a motor (15), an operation section (29), a control section (4), an output shaft (21), and a transmission mechanism (18). An operation unit (29) receives an operation from a user. The control section (4) uses vector control to control the rotation of the motor (15) according to the operation of the operation section (29). The output shaft (21) is connected with the tip tool (28). The tip tool (28) rotates the clamping member (30). A transmission mechanism (18) transmits the rotational force of the motor (15) to the output shaft (21). The control section (4) has a looseness detection function. In the loosening detection function, the control unit (4) controls the motor (15) when the fastening member (30) fastened to the object (100) is loosened from the object (100) by the tip tool (28). Looseness of the tightening member (30) is detected based on the supplied excitation current. The control section (4) reduces the speed of the motor (15) or stops the motor (15) when the loosening of the tightening member (30) is detected.

According to this aspect, the reliability of detecting looseness of the tightening member (30) is improved, and the usability of the power tool (1) can be improved.

In the electric tool (1) of the second aspect, in the first aspect, the rotation direction of the output shaft (21) is the forward rotation direction for fastening the tightening member (30) to the object (100) and the tightening member ( 30) is further provided with a forward/reverse changeover switch (9) for switching between a reverse direction to loosen the object (100). The control section (4) enables the looseness detection function only when the direction of rotation of the tip tool (28) is set to the reverse direction by the forward/reverse selector switch (9).

According to this aspect, when the tightening member (30) is being tightened, unintentional deceleration or stopping of the motor (15) is suppressed.

In the power tool (1) of the third aspect, in the first or second aspect, the transmission mechanism (18) impacts the output shaft (21) according to the magnitude of the torque applied to the output shaft (21). It has an impact mechanism (17) that performs a striking action that applies force.

According to this aspect, the usability of the so-called impact tool having the impact mechanism (17) can be improved.

In the power tool (1) of the fourth aspect, in any one of the first to third aspects, the control section (4), in the looseness detection function, controls the tightening member (30) based on the amplitude of the exciting current. Detect looseness.

According to this aspect, the reliability of looseness detection can be improved, for example, compared to the case where looseness of the tightening member (30) is detected based on the amplitude of the torque current.

In the power tool (1) of the fifth aspect, in any one of the first to fourth aspects, the operating section (29) has a trigger switch. The control section (4) controls the operation of the motor (15) according to the amount of operation of the trigger switch before detecting looseness of the tightening member (30). When the control section (4) detects looseness of the tightening member (30), it limits the speed of the motor (15) to a predetermined upper limit or less.

According to this aspect, the motor (15) can be reliably decelerated when the looseness of the tightening member (30) is detected.

In the electric power tool (1) of the sixth aspect, in any one of the first to fifth aspects, the controller (4), upon detecting loosening of the tightening member (30), speeds up the motor (15) is reduced based on the speed before slack is detected.

According to this aspect, the motor (15) can be reliably decelerated when the looseness of the tightening member (30) is detected.

In the electric power tool (1) of the seventh aspect, in the sixth aspect, when the control section (4) detects loosening of the tightening member (30), the speed of the motor (15) is reduced to a predetermined value. to

According to this aspect, the speed of the motor (15) can be set to an appropriate value regardless of the user's proficiency in operating the power tool (1).

In the electric power tool (1) of the eighth aspect, in any one of the first to seventh aspects, the control section (4), in the looseness detection function, further based on the torque current supplied to the motor (15) to detect loosening of the tightening member (30).

According to this aspect, the reliability of detection of loosening of the tightening member 30 can be further improved.

A power tool (1) according to a ninth aspect is, in any one of the first to eighth aspects, provided with a switching section for switching between enabling and disabling the looseness detection function.

According to this aspect, when the looseness detection function is unnecessary, the function can be disabled, and the usability of the power tool 1 can be improved.

A control method according to a tenth aspect is a control method for a power tool (1). A power tool (1) includes a motor (15), an operating portion (29), an output shaft (21), and a transmission mechanism (18). An operation unit (29) receives an operation from a user. The output shaft (21) is connected with the tip tool (28). The tip tool (28) rotates the clamping member (30). A transmission mechanism (18) transmits the rotational force of the motor (15) to the output shaft (21). The control method includes using vector control to control the rotational movement of the motor (15) in accordance with the operation of the operating section (29). The control method is based on the excitation current supplied to the motor (15) when the clamping member (30) clamped to the object (100) is loosened from the object (100) by the tip tool (28). , detecting loosening of the tightening member (30). The control method includes slowing or stopping the motor (15) upon detecting loosening of the tightening member (30).

According to this aspect, the reliability of detecting looseness of the tightening member (30) is improved, and the usability of the power tool (1) can be improved.

A program of the eleventh aspect is a program for causing one or more processors to execute the control method of the tenth aspect.

According to this aspect, the reliability of detecting looseness of the tightening member (30) is improved, and the usability of the power tool (1) can be improved.

REFERENCE SIGNS LIST 1 electric tool 4 control unit 9 forward/reverse switching switch 15 motor 17 impact mechanism 18 transmission mechanism 21 output shaft 28 tip tool 29 operation unit 30 clamping member 100 object

Claims (12)

a motor;
an operation unit that receives an operation from a user;
a control unit that uses vector control to control the rotational operation of the motor according to the operation of the operation unit;
an output shaft coupled with a tip tool that rotates the tightening member;
a transmission mechanism that transmits the rotational force of the motor to the output shaft;
with
The transmission mechanism does not have an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft,
The control unit
A loosening detection function is provided for detecting loosening of the tightening member based on an exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool. death,
slowing or stopping the motor when the looseness of the tightening member is detected ;
The control unit detects the looseness of the tightening member by detecting a reverse peak after detecting a peak of the excitation current.
Electric tool. wherein, in the looseness detection function, the control unit detects the looseness of the tightening member further based on a torque current supplied to the motor;
The control unit detects the loosening of the tightening member based on a change in the torque current from a state larger than the threshold to a state smaller than the threshold.
The power tool according to claim 1. a motor;
an operation unit that receives an operation from a user;
a control unit that uses vector control to control the rotational operation of the motor according to the operation of the operation unit;
an output shaft coupled with a tip tool that rotates the tightening member;
a transmission mechanism that transmits the rotational force of the motor to the output shaft;
with
The transmission mechanism has an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft,
The control unit
A loosening detection function is provided for detecting loosening of the tightening member based on an exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool. death,
slowing or stopping the motor when the looseness of the tightening member is detected;
The control unit determines that the tightening member is loosened when the amplitude of the excitation current within a predetermined unit time changes from being equal to or greater than a threshold to falling below the threshold.
Electric tool. wherein, in the looseness detection function, the control unit detects the looseness of the tightening member further based on a torque current supplied to the motor;
The control unit
detecting the loosening of the tightening member based on a change in the torque current from a state greater than a threshold to a state less than the threshold; or
detecting the end of the striking action of the impact mechanism by detecting the end of oscillation of the torque current, thereby detecting the loosening of the tightening member;
The power tool according to claim 3. further comprising a forward/reverse selector switch for switching the rotation direction of the output shaft between a forward direction for tightening the tightening member to the object and a reverse direction for loosening the tightening member from the object;
The control unit enables the looseness detection function only when the direction of rotation of the tip tool is set to the reverse direction by the forward/reverse selector switch.
The power tool according to any one of claims 1 to 4. The operation unit includes a trigger switch,
The control unit
before detecting the looseness of the tightening member, controlling the operation of the motor according to the amount of operation of the trigger switch;
limiting the speed of the motor to a predetermined upper limit or less when the looseness of the tightening member is detected;
The power tool according to any one of claims 1-5. When the control unit detects the looseness of the tightening member, the control unit reduces the speed of the motor based on the speed before the looseness is detected.
The power tool according to any one of claims 1-6. When the control unit detects the loosening of the tightening member, the control unit sets the speed of the motor to a predetermined value.
The power tool according to claim 7. A switching unit that switches between enabling and disabling the looseness detection function,
The power tool according to any one of claims 1-8. A control method for a power tool, comprising:
The power tool is
a motor;
an operation unit that receives an operation from a user;
an output shaft coupled with a tip tool that rotates the tightening member;
a transmission mechanism that transmits the rotational force of the motor to the output shaft;
with
The transmission mechanism does not have an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft,
The control method is
using vector control to control the rotational movement of the motor according to the operation of the operation unit;
detecting loosening of the tightening member based on an exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool;
slowing or stopping the motor upon detecting the looseness of the tightening member;
including
Detecting the looseness of the tightening member includes detecting the looseness of the tightening member by detecting a reverse peak after detecting a peak of the excitation current.
control method. A control method for a power tool, comprising:
The power tool is
a motor;
an operation unit that receives an operation from a user;
an output shaft coupled with a tip tool that rotates the tightening member;
a transmission mechanism that transmits the rotational force of the motor to the output shaft;
with
The transmission mechanism has an impact mechanism that performs an impact operation that applies an impact force to the output shaft according to the magnitude of the torque applied to the output shaft,
The control method is
using vector control to control the rotational movement of the motor according to the operation of the operation unit;
detecting loosening of the tightening member based on an exciting current supplied to the motor when the tightening member tightened to the object is loosened from the object by the tip tool;
slowing or stopping the motor upon detecting the looseness of the tightening member;
including
In detecting the loosening of the tightening member, it is determined that the tightening member is loosened when the amplitude of the excitation current within a predetermined unit time changes from being equal to or greater than a threshold to being below the threshold. including to
control method. A program for causing one or more processors to execute the control method according to claim 10 or 11.

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