Power tool system, control method, and program

Abstract

The problem to be overcome by the present invention is to improve user-friendliness. An electric tool system (100) includes: a motor (1); an output shaft (5) that can be coupled to a front-end tool (28); a transmission mechanism (4) that transmits the driving force of the motor (1) to the output shaft (5); an acquirer (31) that acquires a torque value related to the output torque provided by the front-end tool (28) based on the current flowing through the motor (1); a trigger switch (70) that receives an operation command input by a user; and a controller (3) that has a torque management mode in which the controller (3) controls the motor (1) according to the operation command input through the trigger switch (70) and prevents the torque value (Tq1) acquired by the acquirer (31) from exceeding an upper limit value (TqL). When the controller (3) finds that a predetermined condition is satisfied in the torque management mode, regardless of the manipulation variable of the trigger switch (70), it controls the motor (1) to make the speed of the motor (1) become a predetermined limit value. The predetermined condition includes the condition that the torque value acquired by the acquirer (31) reaches a threshold value smaller than the upper limit value.

Description

Technical Field

[0001] The present invention generally relates to a power tool system, a control method, and a program. More particularly, the present invention relates to a power tool system including a motor, a control method for controlling the power tool system, and a program. Background Art

[0002] Patent Document 1 discloses an electric power tool that uses electronic clutch control as a control method. According to the electronic clutch control, when the rotation torque detected by the torque detection member becomes equal to or greater than a predetermined torque setting value, the rotation of the motor is stopped.

[0003] The electronic clutch control enables the user to change the torque setting value. Specifically, according to the electronic clutch control, torque setting values corresponding to nine levels are provided so that the user can select any one of these torque setting values. In addition, according to the electronic clutch control, a maximum number of revolutions is defined for each of these torque setting values of the nine levels. Therefore, according to the electronic clutch control, when the user selects any one of the torque setting values 1 to 9, the controller controls while setting the maximum number of revolutions defined for the selected torque setting value as an upper limit. In the event that it is found that the detected rotational torque is equal to or greater than the torque setting value, the controller forces the motor to stop running regardless of the number of revolutions at that point in time, even if the trigger switch has been pulled.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-139800 Summary of the invention

[0007] The object of the present invention is to increase user-friendliness.

[0008] An electric tool system according to one aspect of the present invention includes a motor, an output shaft, a transmission mechanism, a torque acquirer, a trigger switch, and a controller. The output shaft is capable of being coupled to a front-end tool. The transmission mechanism is configured to transmit motive power of the motor to the output shaft. The torque acquirer acquires a torque value related to an output torque provided by the front-end tool based on a current flowing through the motor. The trigger switch receives an operation command input by a user. The controller has a torque management mode in which the controller controls the motor according to the operation command input through the trigger switch and prevents the torque value acquired by the torque acquirer from exceeding an upper limit value. When the controller finds that a predetermined condition is satisfied in the torque management mode, regardless of the manipulation variable of the trigger switch, the controller controls the motor to change the speed of the motor to a predetermined limit value. The predetermined condition includes a condition that the torque value acquired by the torque acquirer reaches a threshold value smaller than the upper limit value.

[0009] A control method according to another aspect of the present invention is a control method for controlling an electric tool system. The electric tool system includes a motor, an output shaft, a transmission mechanism, a torque acquirer, and a trigger switch. The output shaft is capable of being coupled to a front-end tool. The transmission mechanism transmits motive power of the motor to the output shaft. The torque acquirer acquires a torque value related to an output torque provided by the front-end tool based on a current flowing through the motor. The trigger switch receives an operation command input by a user. The control method includes: controlling the motor in a torque management mode in which the motor is controlled according to the operation command input through the trigger switch and preventing the torque value acquired by the torque acquirer from exceeding an upper limit value. The control method further includes: when it is found that a predetermined condition is satisfied in the torque management mode, regardless of the manipulation variable of the trigger switch, controlling the motor to change the speed of the motor to a predetermined limit value. The predetermined condition includes a condition that the torque value acquired by the torque acquirer reaches a threshold value smaller than the upper limit value.

[0010] A program according to still another aspect of the present invention is designed to cause one or more processors to perform the above control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of an electric tool system according to an exemplary embodiment;

[0012] Figure 2 is a block diagram of the electric tool system;

[0013] Figure 3 illustrates how the controller of the electric tool system performs control;

[0014] Figure 4It is a block diagram of a setter included in a controller of the power tool system;

[0015] Figure 5 It is a graph showing the relationship between the current threshold value and the upper limit value of the power tool system;

[0016] Figure 6 It is a flowchart showing how the controller of the power tool system operates; and

[0017] Figure 7 It is a graph showing an exemplary operation of the power tool system. Detailed Description of the Invention

[0018] Next, the power tool system 100 according to a typical embodiment will be described with reference to the accompanying drawings. Note that the embodiments to be described below are merely typical embodiments among various embodiments of the present invention and should not be construed as restrictive. On the contrary, the typical embodiments can be easily modified in various ways according to design choices or any other factors without departing from the scope of the present invention. The accompanying drawings to be referred to in the following description of the embodiments are all schematic representations. Therefore, the ratio of the dimensions (including thickness) of each component illustrated in the drawings does not always reflect their actual dimensional ratio.

[0019] (1) Overview

[0020] As Figure 1 and Figure 2 shown, the power tool system 100 includes a motor 1, an output shaft 5, a transmission mechanism 4, an acquirer 31, a trigger switch 70, a controller 3, and a power source 8. In the present embodiment, the acquirer 31 is provided for the controller 3.

[0021] The motor 1 operates (rotates) using the electric power supplied from the power source 8 under the control of the controller 3.

[0022] The output shaft 5 is coupled to the front-end tool 28.

[0023] The transmission mechanism 4 transmits the driving force of the motor 1 to the output shaft 5.

[0024] The acquirer 31 acquires a torque value Tq1 related to the output torque provided by the front-end tool 28 based on the current flowing through the motor 1.

[0025] The trigger switch 70 receives the operation command input by the user.

[0026] The controller 3 controls the motor 1.

[0027] In the power tool system 100, the controller 3 has a torque management mode as an operation mode. In the torque management mode, the controller 3 controls the motor 1 according to an operation command input through the trigger switch 70, and also prevents the torque value Tq1 acquired by the acquirer 31 from exceeding the upper limit value TqL. That is to say, in the torque management mode, the so-called "electronic clutch control" is implemented to stop the motor 1 when the torque value Tq1 reaches the upper limit value TqL. In the following description, the torque management mode will be hereinafter referred to as the "electronic clutch mode".

[0028] In addition, in the power tool system 100 according to the present embodiment, when the controller 3 finds that a predetermined condition is satisfied in the electronic clutch mode, regardless of the manipulation variable of the trigger switch 70, it controls the motor 1 to make the speed (rotation speed or number of revolutions) of the motor 1 become a predetermined limit value ωc. The predetermined conditions include the condition that the torque value Tq1 acquired by the acquirer 31 reaches a threshold value smaller than the upper limit value TqL. Therefore, in this power tool system 100, before stopping the motor 1 in response to the torque value Tq1 reaching the upper limit value TqL, the speed of the motor 1 is controlled to the limit value ωc in response to the torque value Tq1 reaching the threshold value. That is to say, in this power tool system 100, the motor 1 is not stopped until the control to make the speed of the motor 1 approach the limit value ωc is performed. This makes it possible to reduce the dispersion of the speed of the motor 1 immediately before stopping the motor 1. This makes it possible to reduce, for example, the dispersion of the tightening torque to be output to the fastening member (such as a screw) in the case of performing a fastening operation (such as a screw tightening operation) on the fastening member using the front-end tool 28. This improves the user-friendliness of the power tool system 100.

[0029] If a motor rotating at a relatively high speed is stopped, sometimes the electronic clutch control cannot be performed due to the inertia of the motor. Figure 5 An exemplary relationship between the upper limit value TqL and the current threshold in the electronic clutch control is shown. As used herein, the "current threshold" refers to the threshold at which the controller 3 stops the motor when the current flowing through the motor reaches this threshold. In Figure 5 ,"X1" represents the characteristic when the motor speed is 23500 [rpm], and "X2" represents the characteristic when the motor speed is 900 [rpm].

[0030] For example, as Figure 5As shown in the figure, if the upper limit value TqL is set to 8 [Nm] when the motor speed is 900 [rpm], the controller determines that the output torque has reached the upper limit value TqL when the current flowing through the motor reaches 54 [A]. On the other hand, if the upper limit value TqL is set to 4 [Nm] when the motor speed is 900 [rpm], the controller determines that the output torque has reached the upper limit value TqL when the current flowing through the motor reaches 24 [A].

[0031] That is, according to electronic clutch control, if the motor speed is constant, there is a linear relationship between the upper limit value TqL and the current threshold. The motor's output torque depends on the current flowing through the motor. Therefore, setting the current threshold to a value that increases as the upper limit value TqL increases increases the final output torque provided by the output shaft when the motor is stopped.

[0032] In addition, if Figure 5 As shown, if the upper limit value TqL is set to 8 [Nm] when the motor speed is 23500 [rpm], the controller determines that the output torque has reached the upper limit value TqL when it finds that the current flowing through the motor has reached 9 [A].

[0033] That is, according to the electronic clutch control, the current threshold for the same upper limit value TqL (8 [Nm] in this example) decreases as the motor speed increases. This phenomenon is caused by motor inertia (ie, the characteristic of the motor that keeps the motor rotating).

[0034] This is why, for example, when the motor speed is 23,500 rpm, there is no current threshold corresponding to the case where the upper limit value TqL is set to a value of 4 Nm (i.e., the current threshold becomes a negative value). In short, if the motor speed is relatively high, electronic clutch control cannot be performed due to the motor inertia (i.e., its inertia moment).

[0035] To overcome this problem, for example, as in the electric power tool of Patent Document 1, a maximum rotational speed can be individually set for each of a plurality of torque setting values (upper limit value TqL). However, in this case, if the upper limit value TqL is a relatively small value, the maximum rotational speed will also be set to a relatively small value. This results in a decrease in the operating rate and an increase in the operating time.

[0036] In the power tool system 100 according to the present embodiment, when the controller 3 detects that a predetermined condition is satisfied, regardless of the manipulation variable of the trigger switch 70, the controller 3 controls the motor 1 to change the rotational speed of the motor 1 to a predetermined limit value ωc. Then, the controller 3 controls the speed of the motor 1 according to the manipulation variable of the trigger switch 70 until the predetermined condition is satisfied. Compared with the power tool of Patent Document 1, this makes it possible to shorten the operation time and thereby improve user-friendliness.

[0037] (2) Details

[0038] (2.1) Power tool system

[0039] Next, the power tool system 100 according to the present embodiment will be described in more detail with reference to the accompanying drawings. The power tool system 100 according to the present embodiment is an electric drill screwdriver.

[0040] As Figure 1 and Figure 2 shown, the power tool system 100 includes a motor 1, an inverter circuit unit 2, a controller 3, a transmission mechanism 4, an output shaft 5, an input / output interface 7, a power source 8, a current measurement device 110, and a motor rotation measurement device 25.

[0041] The motor 1 is a brushless motor. In particular, the motor 1 according to the present embodiment is a synchronous motor. More specifically, the motor 1 may be a permanent magnet synchronous motor (PMSM). As Figure 2 shown, the motor 1 includes a rotor 23 having a permanent magnet 231 and a stator 24 having coils 241. The rotor 23 includes a rotating shaft 26 that outputs rotational power. Due to the electromagnetic interaction between the coils 241 and the permanent magnet 231, the rotor 23 rotates relative to the stator 24.

[0042] The power source 8 is a power source for driving the motor 1. The power source 8 is a DC power source. In the present embodiment, the power source 8 includes a secondary battery. The power source 8 is a so-called "battery pack". The power source 8 can also be used as the power source for the inverter circuit unit 2 and the controller 3.

[0043] The inverter circuit unit 2 is a circuit for driving the motor 1. The inverter circuit unit 2 converts the voltage V dc supplied from the power source 8 into a drive voltage V a used by the motor 1. In the present embodiment, the drive voltage V a is a three-phase AC voltage including a U-phase voltage, a V-phase voltage, and a W-phase voltage. In the following description, the U-phase voltage, the V-phase voltage, and the W-phase voltage will be represented by v u , v v , and v w as needed. These voltages v u , v v and vw is a sinusoidal voltage.

[0044] The inverter circuit unit 2 can be implemented using a PWM inverter and a PWM converter. The PWM converter generates a voltage V a (including U phase voltage v u 、V phase voltage v v and W phase voltage v w ) target value (voltage command value) v u *、v v *、v w *To generate a pulse width modulated PWM signal. The PWM inverter converts the driving voltage V corresponding to the PWM signal a (v u ,v v ,v w ) is applied to the motor 1, thereby driving the motor 1. More specifically, the PWM inverter includes a half-bridge circuit corresponding to the three phases and a driver. In the PWM inverter, the driver turns on (ON) and off (OFF) the switching elements in each half-bridge circuit in response to the PWM signal, thereby converting the voltage command value v u *、v v *、v w * Driving voltage V a (v u ,v v ,v w ) is applied to the motor 1. As a result, the motor 1 is supplied with a driving voltage V a (v u ,v v ,v w ) corresponding to the driving current. The driving current includes the U phase current i u , V phase current i v and W phase current i w More specifically, the U-phase current i u , V phase current i v and W phase current i w These are the current flowing through the U-phase armature winding, the current flowing through the V-phase armature winding, and the current flowing through the W-phase armature winding in the stator 24 of the motor 1 .

[0045] The current measuring device 110 includes two phase current sensors 11. In this embodiment, the two phase current sensors 11 respectively measure the U-phase current i of the drive current supplied from the inverter circuit unit 2 to the motor 1. u and V phase current i v Note that it can be based on the U phase current i u and V phase current i v To calculate the W phase current i wAlternatively, instead of the phase current sensor 11, the current measuring device 110 may include, for example, a current detector using a shunt resistor.

[0046] The transmission mechanism 4 is provided between the rotating shaft 26 of the motor 1 and the output shaft 5. The transmission mechanism 4 transmits the driving force of the motor 1 to the output shaft 5. The transmission mechanism 4 may include, for example, a reduction mechanism that can change the transmission ratio in response to an operation of the speed selector switch.

[0047] The output shaft 5 is a part that rotates by the driving force of the motor 1. The front-end tool 28 may be attached to the output shaft 5 via a chuck 50, for example.

[0048] The front-end tool 28 rotates together with the output shaft 5. The power tool system 100 rotates the front-end tool 28 by rotating the output shaft 5 using the driving force of the motor 1. In other words, the power tool system 100 is a tool for driving the front-end tool 28 using the driving force of the motor 1. Among various types of front-end tools 28, the front-end tool 28 is selected according to the intended use and attached to the chuck 50 for use. Alternatively, the front-end tool 28 may be directly attached to the output shaft 5. Still alternatively, the output shaft 5 and the front-end tool 28 may also be integrated together. Examples of the front-end tool 28 include a screwdriver bit, a drill bit, and a socket wrench. In this example, the front-end tool 28 is a screwdriver bit.

[0049] The input / output interface 7 is a user interface. The input / output interface 7 includes a device for displaying information related to the operation of the power tool system 100, inputting settings related to the operation of the power tool system 100, and operating the power tool system 100.

[0050] In the present embodiment, the input / output interface 7 includes a trigger switch (trigger trigger) 70 and an operation panel 71 for receiving an operation command from the user.

[0051] The trigger switch 70 is a push-button switch. The on / off state of the motor 1 can be switched by operating the trigger switch 70 to be pulled. In addition, the target value ω1* of the speed of the motor 1 can be changed by the manipulation variable of the operation of pulling the trigger switch 70. As a result, the speeds of the motor 1 and the output shaft 5 can be adjusted by the manipulation variable of the operation of pulling the trigger switch 70. The deeper the trigger switch 70 is pulled, the higher the speeds of the motor 1 and the output shaft 5 become.

[0052] More specifically, the trigger switch 70 includes a multi-stage switch or a continuously variable switch (variable resistor) for outputting an operation signal. The operation signal changes according to the manipulation variable of the trigger switch 70 (i.e., how deep the trigger switch 70 is pulled).

[0053] The input / output interface 7 determines the target value ω1* in response to an operation signal supplied from the trigger switch 70, and provides the target value ω1* to the controller 3. The controller 3 starts or stops the operation of the motor 1 and controls the speed of the motor 1 according to the target value ω1* supplied from the input / output interface 7.

[0054] The operation panel 71 has a function of setting the operation mode of the power tool system 100. The operation mode of the power tool system 100 includes at least an electronic clutch mode (torque management mode). The electronic clutch mode is a mode that monitors the output torque of the output shaft 5 (i.e., the output torque provided by the front-end tool 28) and controls the operation of the motor 1 to prevent the output torque from exceeding the set upper limit value TqL. The power tool system 100 according to the present embodiment has the electronic clutch mode as its only operation mode.

[0055] The operation panel 71 also has a function of setting the upper limit value TqL. The operation panel 71 includes, for example, two operation buttons (i.e., an up button and a down button) for setting the upper limit value TqL and a display device. The upper limit value TqL can be selected from a plurality of candidate upper limit values. The currently selected upper limit value TqL is displayed on the display device. For example, when the up button is pressed, the value of the upper limit value TqL displayed on the display device increases. When the down button is pressed, the value of the upper limit value TqL displayed on the display device decreases. The operation panel 71 outputs the value displayed on the display device as the upper limit value TqL to the controller 3.

[0056] That is to say, the power tool system 100 includes an upper limit value setting unit (operation panel 71) for setting one of the plurality of candidate upper limit values as the upper limit value TqL.

[0057] The motor rotation measuring device 25 measures the rotation angle of the motor 1. As the motor rotation measuring device 25, for example, an optical encoder or a magnetic encoder can be used. Based on the rotation angle of the motor 1 measured by the motor rotation measuring device 25 and its change, the rotor position θ and speed ω of the motor 1 (rotor 23) can be obtained.

[0058] The controller 3 determines the command value ω2* of the speed of the motor 1. In particular, the controller 3 determines the command value ω2* of the speed of the motor 1 based on the target value ω1* of the speed of the motor 1 provided by the trigger switch 70. In addition, the controller 3 also determines the target value (voltage command value) v a * of the drive voltage V u *, v v *, and v w * such that the speed of the motor 1 coincides with the command value ω2*, and gives these target values to the inverter circuit unit 2.

[0059] (2.2) Controller

[0060] Next, the controller 3 will be described in more detail. In this embodiment, the controller 3 controls the motor 1 through vector control. Vector control is a motor control method in which the motor current is decomposed into a current component that generates torque (rotational power) and a current component that generates magnetic flux, and these current components are controlled independently of each other.

[0061] Figure 3 An analytical model of the motor 1 according to vector control is shown. Figure 3 , the armature winding fixed axes of the U-phase, V-phase, and W-phase are shown. According to vector control, a rotating coordinate system is considered, which rotates at a rotation speed as high as the rotation speed of the magnetic flux generated by the permanent magnet 231 provided for the rotor 23 of the motor 1. In the rotating coordinate system, the direction of the magnetic flux generated by the permanent magnet 231 is defined by the d-axis, and the rotation axis corresponding to the d-axis in control is defined by the γ-axis. The q-axis is set at a phase that is 90 degrees ahead of the d-axis in electrical angle. The δ-axis is set at a phase that is 90 degrees ahead of the γ-axis in electrical angle. The rotating coordinate system corresponding to the real axis is a coordinate system that selects the d-axis and the q-axis as its coordinate axes (which will be referred to as the "dq-axis" hereinafter). The rotating coordinate system in control is a coordinate system that selects the γ-axis and the δ-axis as its coordinate axes (which will be referred to as the "γδ-axis" hereinafter).

[0062] The dq axis has rotated, and the rotation speed of the dq axis is specified by ω. The γδ axis has also rotated, and the rotation speed of the γδ axis is specified by ωe. In addition, in the dq axis, the angle (phase) of the d axis as viewed from the U-phase armature winding fixed axis is specified by θ. In the same way, in the γδ axis, the angle (phase) of the γ axis as viewed from the U-phase armature winding fixed axis is specified by θe. The angles specified by θ and θe are angles as electrical angles, and are generally referred to as "rotor positions" or "magnetic pole positions". The rotation speed specified by ω and ωe is the angular velocity expressed in electrical angles. In the following description, θ or θe will sometimes be referred to as "rotor position" hereinafter, and ω or ωe will be simply referred to as "speed" hereinafter.

[0063] Basically, the controller 3 performs vector control so that θ and θe are consistent with each other. If θ and θe are consistent with each other, the d-axis and the q-axis are consistent with the γ-axis and the δ-axis, respectively. In the following description, the drive voltage V a The γ-axis component and δ-axis component will be respectively determined by the γ-axis voltage v γ and the delta axis voltage v δ Indicated by, and the γ-axis component and δ-axis component of the driving current will be respectively represented by the γ-axis current i γ and the δ-axis current i δ express.

[0064] In addition, the γ-axis voltage vγ and the delta axis voltage v δ The voltage command values of each target value will be respectively determined by the γ-axis voltage command value v γ * and the δ-axis voltage command value v δ * indicates. In addition, it indicates the γ-axis current i γ and the δ-axis current i δ The current command values of each target value will be respectively determined by the γ-axis current command value i γ * and the δ-axis current command value i δ *express.

[0065] Controller 3 performs vector control so that the γ-axis voltage v γ and the delta axis voltage v δ The values follow the γ-axis voltage command value v γ * and the δ-axis voltage command value v δ *, and make the γ-axis current i γ and the δ-axis current i δ The values follow the γ-axis current command value i γ * and the δ-axis current command value i δ *.

[0066] The controller 3 includes a computer system including one or more processors and memory. At least some of the functions of the controller 3 are performed by having the computer system's processor execute a program stored in the computer system's memory. The program may be pre-stored in the memory. Alternatively, the program may be downloaded via an electrical communication line such as the Internet, or distributed after being stored in a non-transitory storage medium such as a memory card.

[0067] like Figure 2 As shown, the controller 3 includes a coordinate converter 12, a subtractor 13, another subtractor 14, a current controller 15, a magnetic flux controller 16, a speed controller 17, another coordinate converter 18, yet another subtractor 19, a position and speed estimator 20, a step-out detector 21, and a setter 22. Note that the coordinate converter 12, the subtractors 13, 14, 19, the current controller 15, the magnetic flux controller 16, the speed controller 17, the coordinate converter 18, the position and speed estimator 20, the step-out detector 21, and the setter 22 represent respective functions to be performed by the controller 3. Therefore, the respective constituent elements of the controller 3 can freely use the respective values generated inside the controller 3.

[0068] The setter 22 generates a command value ω2* for the speed of the motor 1. The setter 22 determines the command value ω2* based on the target value ω1* and other values provided by the input / output interface 7. The setter 22 will be described in detail later in the "(2.3) Command Value" section.

[0069] The coordinate converter 12 is based on the rotor position θ e To calculate the U phase current i on the γδ axis u and V phase current i v Perform coordinate transformation to calculate and output the γ-axis current i γ and the δ-axis current i δ As used herein, the γ-axis current i γ It is an excitation current that corresponds to the d-axis current and hardly contributes to the torque. On the other hand, the δ-axis current i δ The current that corresponds to the q-axis current and contributes significantly to the torque. e is calculated by the position and velocity estimator 20 .

[0070] The subtracter 19 refers to the speed ωe and the command value ω2* and calculates a speed deviation (ω2*−ωe) between the speed ωe and the command value ω2*. The speed ωe is calculated by the position and speed estimator 20.

[0071] The speed controller 17 calculates the delta axis current command value i by, for example, proportional integral control. δ *, so that the speed deviation (ω2*–ωe) converges to zero, and outputs the δ-axis current command value i thus calculated δ *.

[0072] The magnetic flux controller 16 determines the γ-axis current command value i γ *, and the γ-axis current command value i γ * Output to the subtractor 13. For example, the γ-axis current command value i γ * can have any of various values depending on the type of vector control performed by the controller 3 and the speed ω of the motor 1. For example, if 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. On the other hand, if the field weakening control is performed while the d-axis current is allowed to flow, the γ-axis current command value i γ * is set to a negative value corresponding to the speed ωe. In the following description, the γ-axis current command value i γ * is zero.

[0073] The subtractor 13 calculates the γ-axis current command value i provided by the magnetic flux controller 16. γ *Subtract the γ-axis current i provided by the coordinate converter 12 γ , and calculate the current error (i γ *–i γ ). The subtractor 14 subtracts the value i provided by the speed controller 17 from δ *Subtract the δ-axis current i provided by the coordinate converter 12δ , from which the current error (i δ *–i δ ) is calculated.

[0074] The current controller 15 performs current feedback control, for example, by proportional-integral control, such that both the current errors (i γ *–i γ ) and (i δ *–i δ ) converge to zero. In this case, the current controller 15 calculates the γ-axis voltage command value v γ * and the δ-axis voltage command value v δ * by using non-interference control for eliminating interference between the γ-axis and the δ-axis, so that both (i γ *–i γ ) and (i δ *–i δ ) converge to zero.

[0075] Based on the rotor position θe provided by the position and speed estimator 20, the coordinate converter 18 performs coordinate conversion on the γ-axis voltage command value v γ * and the δ-axis voltage command value v δ * provided by the current controller 15 on the fixed coordinate axes of three phases, thereby calculating and outputting the voltage command values (v u *, v v * and v w *).

[0076] The inverter circuit unit 2 supplies the three-phase voltage corresponding to the voltage command values (v u *, v v * and v w *) supplied by the coordinate converter 18 to the motor 1. In response, the motor 1 is driven by the electric power (three-phase voltage) supplied from the inverter circuit unit 2 and generates rotational power.

[0077] The position and speed estimator 20 estimates the rotor position θe and the speed ωe. More specifically, the position and speed estimator 20 can perform, for example, proportional-integral control by using some or all of i γ and i δ provided by the coordinate converter 12 and v γ * and v δ * provided by the current controller 15. The position and speed estimator 20 estimates the rotor position θe and the speed ωe such that the axis error (θe–θ) between the d-axis and the γ-axis converges to zero. Note that various methods for estimating the rotor position θe and the speed ωe have been proposed in the art. The position and speed estimator 20 can adopt any of these various known methods.

[0078] The out-of-step detector 21 determines whether an out-of-step (asynchronism) has occurred in the motor 1. More specifically, the out-of-step detector 21 determines whether an out-of-step has occurred in the motor 1 based on the magnetic flux of the motor 1. It is possible to obtain the magnetic flux of the motor 1 based on 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 *. When it is found that the amplitude of the magnetic flux of the motor 1 is less than the threshold value, the out-of-step detector 21 may determine that an out-of-step has occurred in the motor 1. Note that the threshold value can be appropriately determined based on the amplitude of the magnetic flux generated by the permanent magnet 231 of the motor 1. Various known methods for detecting out-of-step have been proposed in the art. The out-of-step detector 21 can adopt any of these various known methods.

[0079] (2.3) Command value

[0080] As described above, the controller 3 controls the operation of the motor 1 such that the speed ωe of the motor 1 coincides with the command value ω2* of the speed of the motor 1 generated by the setter 22. Next, how the setter 22 performs the operation for generating the command value ω2* will be described.

[0081] The setter 22 determines the command value ω2* based on the target value ω1* and the upper limit value TqL provided by the input / output interface 7, the speed ωe of the motor 1, and the torque value Tq1 acquired by the acquirer 31.

[0082] In the present embodiment, as Figure 4 shown, the acquirer 31 is included in the setter 22 in the present embodiment. The acquirer 31 acquires the value of the δ-axis current i δ from the coordinate converter 12. As described above, the δ-axis current i δ corresponds to the q-axis current and is a current component that makes a significant contribution to the torque. The acquirer 31 acquires the torque value Tq1 related to the output torque provided by the front-end tool 28 based on the δ-axis current i δ . In the following description, for convenience, the δ-axis current i δ will be hereinafter referred to as "torque current". In short, the acquirer 31 acquires the torque value Tq1 based on the torque current (δ-axis current i δ ) flowing through the motor 1.

[0083] In this case, the acquirer 31 corrects the δ-axis current i δ based on the acceleration of the motor 1, and acquires the torque value Tq1 based on the value thus obtained (i.e., the corrected δ-axis current). That is, if the speed of the motor 1 changes (i.e., if the motor 1 accelerates or decelerates), the δ-axis current i δIt includes not only the current component for generating the output torque of the output shaft 5, but also the current component for changing the speed of the motor 1. Therefore, the acquirer 31 corrects the δ-axis current i according to the acceleration of the motor 1 δ to obtain the current component for generating the output torque of the output shaft 5, and obtains the torque value Tq1 based on the current component thus obtained.

[0084] The present inventor has conducted extensive research and found that the current component of the δ-axis current i for changing the speed of the motor 1 δ has a linear relationship with the acceleration of the motor 1 (i.e., the change in the number of revolutions). The present inventor has found that in one experimental example, the equation Y = 0.095x + 2.5 is satisfied, where Y [A] is the current component of the δ-axis current i for changing the speed of the motor 1 δ and x [rpm / s] is the acceleration (change in the number of revolutions) of the motor 1. Therefore, the current component for generating the output torque of the output shaft 5 (i.e., the corrected δ-axis current) in the δ-axis current i δ can be obtained by subtracting the Y value as the correction value from the value of the δ-axis current i δ . In the following description, for convenience, the corrected δ-axis current will be hereinafter referred to as "corrected torque current".

[0085] The setter 22 has a normal operation mode and a constant speed operation mode.

[0086] When the power tool system 100 starts to operate, the setter 22 operates in the normal operation mode. In the normal operation mode, the setter 22 sets the target value ω1* provided by the input / output interface 7 as the command value ω2*. In the normal operation mode, the command value ω2* is consistent with the target value ω1*.

[0087] When a predetermined condition is satisfied while the setter 22 is operating in the normal operation mode, the operation mode of the setter 22 is switched from the normal operation mode to the constant speed operation mode.

[0088] In the constant speed operation mode, the setter 22 sets the "limit value ωc" as the command value ω2*. The limit value ωc is a value to be determined according to the upper limit value TqL set by the upper limit value setting unit (operation panel 71). In the constant speed operation mode, the command value ω2* is consistent with the limit value ωc.

[0089] In addition, in both the normal operation mode and the constant speed operation mode, when the torque value Tq1 obtained by the acquirer 31 reaches the upper limit value TqL, the setter 22 sets the command value ω2* to zero to stop the operation of the motor 1 (i.e., perform electronic clutch control).

[0090] More specifically, as Figure 4As shown, the setter 22 includes not only the acquirer 31, but also a first threshold setter 221, a speed setter 222, a switching determiner 223, a second threshold setter 224, a stop determiner 225, and a command value generator 226.

[0091] The first threshold setter 221 sets a first threshold Th1 based on the upper limit value TqL set by the upper limit value setting unit (see Figure 7 ). The first threshold Th1 is a value to be compared with the corrected torque current (i.e., the corrected δ-axis current) by the switching determiner 223 when the setter 22 is operating in the normal operation mode. A plurality of candidate first thresholds corresponding one-to-one to a plurality of candidate upper limit values are registered in advance. The candidate first threshold corresponding to the upper limit value TqL set by the upper limit value setting unit is selected as the first threshold Th1. If the corrected torque current reaches the first threshold Th1, it means that the output torque has reached the threshold. In short, the threshold is a value depending on the upper limit value set by the upper limit value setting unit.

[0092] The speed setter 222 sets a limit value ωc based on the upper limit value TqL set by the upper limit value setting unit. The limit value ωc is the value set as the command value ω2* by the setter 22 when the setter 22 is operating in the constant speed operation mode. In addition, the limit value ωc is also a value to be compared with the speed ωe of the motor 1 by the switching determiner 223 when the setter 22 is operating in the normal operation mode. A plurality of candidate limit values corresponding one-to-one to a plurality of candidate upper limit values are registered in advance. The candidate limit value corresponding to the upper limit value TqL set by the upper limit value setting unit is selected as the limit value ωc. In short, the limit value ωc is a value depending on the upper limit value set by the upper limit value setting unit.

[0093] The switching determiner 223 determines whether to switch the operation mode of the setter 22 from the normal operation mode to the constant speed operation mode. When it is found that a predetermined condition is satisfied, the switching determiner 223 switches the operation mode of the setter 22 from the normal operation mode to the constant speed operation mode. In this case, the predetermined condition includes a first condition and a second condition.

[0094] The first condition is the condition that the torque value Tq1 acquired by the acquirer 31 reaches the threshold. In particular, the first condition is the condition that the torque value Tq1 increases from a value smaller than the threshold to reach the threshold.

[0095] In this case, switching determiner 223 compares the correction torque current (i.e., the corrected delta-axis current) with a first threshold value Th1. Upon finding that the correction torque current has reached the first threshold value Th1, switching determiner 223 determines that torque value Tq1 has reached the threshold value. In other words, the output torque of motor 1 depends on the correction torque current flowing through motor 1. Therefore, switching determiner 223 is configured to determine that torque value Tq1 has reached the threshold value upon finding that the correction torque current has reached the first threshold value Th1.

[0096] In the normal operation mode, the switching determiner 223 compares the correction torque current with the first threshold Th1 as needed to determine whether the correction torque current has reached the first threshold Th1 .

[0097] The second condition is a condition that the speed ωe (or speed ω) of the motor 1 is equal to or greater than the limit value ωc set by the speed setter 222. The switching determiner 223 compares the speed ωe of the motor 1 with the limit value ωc in the normal operation mode to determine whether the speed ωe is equal to or greater than the limit value ωc.

[0098] In short, the predetermined conditions include the condition (as a first condition) that the torque value Tq1 acquired by the acquirer 31 reaches a threshold value smaller than the upper limit value TqL. The predetermined conditions also include the condition (as a second condition) that the speed ωe of the motor 1 is equal to or greater than the limit value ωc.

[0099] Upon finding both the first condition and the second condition satisfied, the switch determiner 223 determines that the predetermined condition is satisfied, and switches the operation mode of the setter 22 from the normal operation mode to the constant speed operation mode.

[0100] The second threshold value setter 224 sets the second threshold value Th2 based on the upper limit value TqL set by the upper limit value setting unit and the speed ωe (or speed ω) of the motor 1 (see Figure 7 The second threshold Th2 is a value to be compared with the correction torque current (ie, the corrected delta-axis current) by the stop determiner 225 when the setter 22 is operating in each of the normal operation mode and the constant speed operation mode. The second threshold Th2 is greater than the first threshold Th1.

[0101] The second threshold value setter 224 sets the second threshold value Th2 for a certain upper limit value TqL set by the upper limit value setting unit so that the second threshold value Th2 decreases as the speed ωe of the motor 1 increases. Furthermore, the second threshold value setter 224 also sets the second threshold value Th2 for a certain speed ωe of the motor 1 so that the second threshold value Th2 increases as the upper limit value TqL increases.

[0102] As described above, in the constant speed operating mode, the speed ωe of the motor 1 is controlled toward the limit value ωc, and therefore the second threshold value Th2 is also controlled toward a value corresponding to the set upper limit value TqL. That is, in the constant speed operating mode, the second threshold value Th2 remains constant unless the upper limit value TqL changes.

[0103] On the other hand, in the normal operation mode, the speed ωe of the motor 1 varies with time according to the target value ω1* provided by the input / output interface 7. Therefore, in the normal operation mode, the second threshold Th2 may vary with time.

[0104] The stop determiner 225 determines whether a stop condition is satisfied in the normal operation mode and the constant speed operation mode. The stop condition includes a condition that the correction torque current (ie, the corrected delta-axis current) reaches a second threshold value Th2.

[0105] The stop determiner 225 compares the correction torque current with the second threshold Th2 as needed. When the correction torque current reaches the second threshold Th2, the stop determiner 225 determines that the torque value Tq1 has reached the upper limit value TqL and issues a command to the command value generator 226 to stop the motor 1.

[0106] The command value generator 226 generates the command value ω2*. In the normal operation mode, the command value generator 226 sets the target value ω1* provided by the input / output interface 7 as the command value ω2*. On the other hand, in the constant speed operation mode, the command value generator 226 sets the limit value ωc generated by the speed setter 222 as the command value ω2*.

[0107] Furthermore, command value generator 226 sets command value ω2* to zero upon receiving a command to stop motor 1 from stop determiner 225. That is, controller 3 stops motor 1 upon finding that torque value Tq1 has reached upper limit value TqL.

[0108] Next, refer to Figure 6 The flowchart shown briefly explains how the setter 22 operates.

[0109] When the trigger switch 70 is turned on, the setter 22 starts operating in the normal operation mode (in S1), acquires the upper limit value TqL from the input / output interface 7, and generates and sets the first threshold value Th1, the second threshold value Th2, and the limit value ωc based on the upper limit value TqL thus acquired. Then, the setter 22 outputs the target value ω1* that depends on the depth to which the trigger switch 70 is pulled as the command value ω2* (in S2) to start the operation of the motor 1. After the motor 1 has started operating, the setter 22 acquires the speed ωe and the torque current (δ-axis current i ) of the motor 1 as needed. δ ).

[0110] In the normal operation mode, the setter 22 determines as needed whether a stop condition is satisfied (at S3). If the stop condition is satisfied (if the answer at S3 is "yes"), the setter 22 outputs 0 [rpm] as the command value ω2* and stops the motor 1 from running (at S8). On the other hand, unless the stop condition is satisfied (if the answer at S3 is "no"), the setter 22 determines whether a predetermined condition (including a first condition and a second condition) is satisfied (at S4). Unless the predetermined condition is satisfied (if the answer at S4 is "no"), the setter 22 continues to operate in the normal operation mode.

[0111] On the other hand, if the predetermined condition is satisfied (if the answer at S4 is "yes"), the setter 22 starts to operate in the constant speed operation mode (at S5). If the upper limit value TqL has been changed by the upper limit value setting unit, the setter 22 acquires the upper limit value TqL from the input / output interface 7 and sets the first threshold Th1, the second threshold Th2, and the limit value ωc. Then, the setter 22 outputs the limit value ωc as the command value ω2* (at S6). The setter 22 operates the motor 1 such that the speed of the motor 1 becomes equal to the limit value ωc, and then acquires the speed ωe and the torque current (δ-axis current i δ ) of the motor 1 as needed.

[0112] When operating in the constant speed operation mode, the setter 22 determines as needed whether a stop condition is satisfied (at S7). Unless the stop condition is satisfied (if the answer at S7 is "no"), the setter 22 continues to operate in the constant speed operation mode. On the other hand, if the stop condition is satisfied (if the answer at S7 is "yes"), the setter 22 outputs 0 [rpm] as the command value ω2* to stop the motor 1 from running (at S8).

[0113] (2.4) Exemplary operation

[0114] Next, the exemplary operation of the power tool system 100 will be described with reference to Figure 7 .

[0115] In Figure 7 , "A1" represents the speed ω [rpm] of the motor 1, "A2" represents the command value ω2* [rpm], and "A3" represents the corrected torque current [A]. Note that "A4" represents the torque current (δ-axis current i δ ) [A] that has not been corrected by the acquirer 31.

[0116] In addition, in Figure 7where “B1” represents the limit value ωc [rpm] of the speed of motor 1, “Th1” represents the first threshold Th1 [A], and “Th2” represents the second threshold Th2 [A]. In Figure 7 the example shown, the limit value ωc of the speed of motor 1 is set to 10000 [rpm], and the first threshold Th1 is set to 15 [A]. Further, the second threshold Th2 is set to 20 A from time point t3. Note that the time period from time point t0 to time point t3 is a mask period during which the stop determiner 225 does not operate. That is, even if the correction torque current exceeds the second threshold Th2 during the mask period, the controller 3 does not stop the operation of motor 1. This can reduce the possibility that motor 1 cannot start operating. In Figure 7 it, the second threshold Th2 of 0 [A] indicates that the stop determiner 225 does not operate (during the time period from time point t0 to time point t3).

[0117] When the user operates the pull trigger switch 7 with the front-end tool 28 placed on the head of a fastening member (e.g., a wood screw), the setter 22 starts operating in the normal operation mode, and motor 1 starts running (at time point t0). Accordingly, current starts to be supplied to motor 1, and the torque current increases. Thereafter, from not later than approximately time point t1 to approximately time point t4, the command value ω2* continues to increase. As a result, the speed ω of motor 1 also continues to increase. Note that the time period from time point t1 to time point t4 is a time period during which the wood screw is to be screwed into the guide hole. Accordingly, during this time period, the torque current includes, as its main component, a current component that changes the speed of motor 1 (i.e., accelerates motor 1), and the correction torque current is approximately equal to 0 [A].

[0118] When operating in the normal operation mode, the setter 22 stably determines as needed whether a predetermined condition (including a first condition and a second condition) is satisfied. In this example, at time point t2, the speed ω of motor 1 reaches the limit value ωc, and thus the second condition is satisfied from time point t2.

[0119] At time point t5, the wood screw reaches the bottom of the guide hole. From this time point, the torque current and the correction torque current increase, and the speed of motor 1 decreases.

[0120] When it is found that the correction torque current has reached the first threshold Th1 (at time point t6), the controller 3 (setter 22) determines that the first condition (and the second condition) is satisfied, and switches the operation mode to the constant speed operation mode. This enables the command value ω2* to be forcibly controlled toward the limit value ωc. In this case, the controller 3 (setter 22) changes the speed (command value ω2*) of motor 1 to the limit value ωc in a single step.

[0121] Thereafter, when it is detected that the correction torque current has reached the second threshold Th2 (at time point t7), the setter 22 sets the command value ω2* to 0 [rpm] and stops the motor 1.

[0122] Note that in the operation of tightening the screw, if the correction torque current reaches the second threshold Th2 (at time point t7), this may mean that the head of the screw has been fixed to the work object.

[0123] As can be seen from the above description, in the power tool system 100 according to the present embodiment, when it is detected that a predetermined condition is satisfied in the electronic clutch mode (at time point t6), regardless of the manipulation variable of the trigger switch 70, the controller 3 controls the motor 1 such that the speed of the motor 1 becomes equal to the predetermined limit value ωc (10,000 [rpm]). This makes it possible to avoid a situation where electronic clutch control cannot be performed. In addition, this can also reduce the dispersion of the speed of the motor 1 immediately before stopping the motor 1. This makes it possible to reduce the dispersion of the tightening torque output from the front-end tool 28 to the work object, thereby improving the user-friendliness of the power tool system 100.

[0124] (3) Modification Example

[0125] Note that the above-described embodiment is merely a typical example among various embodiments of the present invention and should not be construed as restrictive. On the contrary, without departing from the scope of the present invention, the typical example can be easily modified in various ways according to design choices or any other factors. Next, modification examples of the typical example will be listed one by one.

[0126] The functions performed by the controller 3 of the power tool system 100 can also be implemented as a method for controlling the power tool system 100, a (computer) program, or a non-transitory storage medium storing the program.

[0127] According to one aspect, a control method is a control method for controlling an electric tool system 100. The electric tool system 100 includes a motor 1, an output shaft 5, a transmission mechanism 4, an acquirer 31, and a trigger switch 70. The output shaft 5 is capable of being connected to a front end tool 28. The transmission mechanism 4 transmits the motive force of the motor 1 to the output shaft 5. The acquirer 31 acquires a torque value Tq1 related to the output torque provided by the front end tool 28 based on the current flowing through the motor 1. The trigger switch 70 receives an operation command input by a user. The control method includes: controlling the motor 1 in a torque management mode, in which the motor 1 is controlled according to the operation command input through the trigger switch 70, and preventing the torque value Tq1 acquired by the acquirer 31 from exceeding an upper limit value TqL. The control method also includes: when it is found that a predetermined condition is satisfied in the torque management mode, regardless of the manipulated variable of the trigger switch 70, controlling the motor 1 so that the speed of the motor 1 becomes a predetermined limit value ωc. The predetermined condition includes a condition that the torque value Tq1 acquired by the acquirer 31 reaches a threshold value smaller than the upper limit value TqL.

[0128] A program according to another aspect is designed to cause one or more processors to perform the above-described method for controlling the power tool system 100. The program may be distributed after being stored in a non-transitory storage medium.

[0129] The main body that performs the functions of the above-described controller 3 includes a computer system. The computer system includes a processor and a memory as main hardware components. A part of the functions of the controller 3 according to the present invention can be performed by causing the processor to execute a program stored in the memory of the computer system. The program can be pre-stored in the memory of the computer system. Alternatively, the program can also be downloaded via an electrical communication line, or can be distributed after being recorded on some non-transitory storage medium such as a memory card, an optical disc, or a hard disk drive (any of which is readable by the computer system). The processor of the computer system can be implemented as a single or multiple electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). As used herein, an "integrated circuit" such as an IC or an LSI is referred to by different names depending on its degree of integration. Examples of integrated circuits include system LSI, very large-scale integrated circuit (VLSI), and ultra-large-scale integrated circuit (ULSI). Optionally, a field-programmable gate array (FPGA) that is to be programmed after manufacturing the LSI, or a reconfigurable logic device that allows reconfiguration of connections or circuit sections inside the LSI can also be used as the processor. These electronic circuits can be integrated together on a single chip or distributed on multiple chips, either of which is appropriate. These multiple chips can be aggregated together in a single device or distributed in multiple devices without limitation. As used herein, a "computer system" includes a microcontroller that includes one or more than one processor and one or more than one memory. Therefore, the microcontroller can also be implemented as a single or multiple electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0130] Furthermore, in the above-described embodiment, the multiple functions of the controller 3 are aggregated together in a single housing. However, this is not a necessary configuration. Alternatively, these constituent elements of the controller 3 can be distributed in multiple different housings. Still alternatively, as in the above basic example, the multiple functions of the controller 3 can be aggregated together in a single housing. In addition, at least some of the functions of the controller 3 can also be implemented as a cloud computing system.

[0131] In a modified example, when it is found that a predetermined condition is satisfied, the controller 3 (the setter 22) can gradually change the speed (command value ω2*) of the motor 1 to the limit value ωc in multiple steps. When it is found that a predetermined condition is satisfied, the controller 3 (the setter 22) can linearly or over time change the speed (command value ω2*) of the motor 1 to the limit value ωc in an S-curve, concave-down, or concave-up shape.

[0132] In another modification example, the predetermined condition consists only of the first condition. In this case, if the first condition is satisfied when the motor 1 is rotating at a low speed that does not satisfy the second condition (i.e., when the speed of the motor 1 is less than the limit value ωc), the speed (command value ω2*) of the motor 1 is increased to the limit value ωc.

[0133] In yet another modification example, even when only one of the first condition and the second condition is satisfied first and then only the other of the first condition and the second condition is satisfied, the controller 3 (the setter 22) may determine that the predetermined condition is not satisfied. For example, when it is found that the first condition is satisfied, the controller 3 sets the first flag. When it is found that the second condition is satisfied, the controller 3 sets the second flag. Then, when it is found that both the first flag and the second flag are set, the controller 3 determines that the predetermined condition is satisfied. For example, when it is found that only the first flag is set because the first condition is only satisfied at a certain time point while the second condition is not satisfied, the controller 3 will reset the first flag later. When it is found that only the second condition is satisfied at a subsequent time point while the first condition is not satisfied, the controller 3 determines that only the second flag is set and the predetermined condition is not satisfied.

[0134] Conversely, when only one of the first condition and the second condition is satisfied first and then only the other of the first condition and the second condition is satisfied, the controller 3 (the setter 22) may determine that the predetermined condition is satisfied. In this case, when it is found that only the first flag is set because the first condition is only satisfied at a certain time point while the second condition is not satisfied, the controller 3 does not reset the first flag.

[0135] In yet another modification example, the operation mode of the power tool system 100 may include at least one other mode in addition to the electronic clutch mode. Examples of other modes may include, for example, the basic mode. In the basic mode, regardless of the magnitude of the output torque provided by the output shaft 5, the power tool system 100 always rotates the motor 1 at a speed that varies according to the depth at which the trigger switch 70 is pulled. The operation mode of the power tool system 100 can be changed, for example, by operating a selector switch provided for the operation panel 71.

[0136] In yet another modification example, the first threshold Th1 may be proportional to the second threshold Th2. For example, the first threshold Th1 may be a value 0.5 to 0.7 times larger than the second threshold Th2.

[0137] In yet another modification example, the setter 22 does not have to obtain the corrected torque current. That is, the setter 22 (including the switching determination unit 223 and the stop determination unit 225) may compare the torque current rather than the corrected torque current with the first threshold Th1 and the second threshold Th2.

[0138] In yet another modification, the setter 22 (switching determination unit 223) may compare, in the normal operation mode, the command value ω2* of the speed of the motor 1 rather than the speed of the motor 1 with the limit value ωc.

[0139] In yet another modification, it is possible to determine whether a certain threshold value (which may be the first threshold value Th1, the second threshold value Th2, or the limit value ωc) has been reached or whether the value in question is equal to or greater than the certain threshold value based on determinations made a plurality of times (e.g., five times). This can reduce the influence of noise.

[0140] In yet another modification, when it is found that the target value ω1* is less than the limit value ωc during operation in the constant speed operation mode, the setter 22 may switch its operation mode to the normal operation mode.

[0141] (4) Aspects

[0142] The above-described embodiments, their modifications, and their equivalents may be specific implementations of the following aspects of the present invention.

[0143] An electric power tool system (100) according to a first aspect includes a motor (1), an output shaft (5), a transmission mechanism (4), an acquirer (31), a trigger switch (70), and a controller (3). The output shaft (5) is connectable to a front-end tool (28). The transmission mechanism (4) transmits the motive power of the motor (1) to the output shaft (5). The acquirer (31) acquires a torque value (Tq1) related to the output torque provided by the front-end tool (28) based on the current flowing through the motor (1). The trigger switch (70) receives an operation command input by a user. The controller (3) has a torque management mode in which the controller (3) controls the motor (1) according to the operation command input through the trigger switch (70) and prevents the torque value (Tq1) acquired by the acquirer (31) from exceeding an upper limit value (TqL). The controller (3) controls the motor (1) to make the speed of the motor (1) become a predetermined limit value (ωc) regardless of the manipulation variable of the trigger switch (70) when a predetermined condition is satisfied in the torque management mode. The predetermined condition includes a condition that the torque value (Tq1) acquired by the acquirer (31) reaches a threshold value smaller than the upper limit value (TqL).

[0144] According to this aspect, before the motor (1) is stopped in response to the torque value (Tq1) reaching the upper limit value (TqL), the speed of the motor (1) is controlled to the limit value (ωc) in response to the torque value (Tq1) reaching the threshold value. That is, the motor (1) is not stopped until the speed of the motor (1) once approaches the limit value (ωc). This makes it possible to reduce the dispersion of the speed (ωe) of the motor (1) immediately before the motor (1) is stopped, thereby improving user-friendliness.

[0145] The electric tool system (100) according to the second aspect, which can be implemented in combination with the first aspect, further includes an upper limit value setting unit (operation panel 71). The upper limit value setting unit sets one of a plurality of candidate upper limit values as the upper limit value (TqL).

[0146] This aspect enables the user to select the upper limit value (TqL) he or she desires.

[0147] In the electric tool system (100) according to the third aspect, which can be implemented in combination with the second aspect, the limit value (ωc) is a value that depends on the upper limit value (TqL) set by the upper limit value setting unit.

[0148] This aspect enables the setting of a limit value (ωc) that depends on the upper limit value (TqL), thereby enabling the motor 1 to operate at a speed (limit value ωc) suitable for the magnitude (upper limit value TqL) of the desired fastening torque.

[0149] In the electric tool system (100) according to the fourth aspect, which can be implemented in combination with the second aspect or the third aspect, the threshold value is a value that depends on the upper limit value (TqL) set by the upper limit value setting unit.

[0150] This aspect enables the setting of a threshold value that depends on the upper limit value (TqL).

[0151] In the electric tool system (100) according to the fifth aspect, which can be implemented in combination with any one of the first aspect to the fourth aspect, the controller (3) controls the motor (1) by vector control. The acquirer (31) acquires a torque value (Tq1) based on the torque current flowing through the motor (1).

[0152] This aspect enables the acquisition of the torque value (Tq1) by using the torque current used in vector control and does not require the provision of, for example, an additional dedicated sensor, thus contributing to simplifying the configuration.

[0153] In the electric tool system (100) according to the sixth aspect, which can be implemented in combination with any one of the first aspect to the fifth aspect, the controller (3) controls the speed of the motor (1) according to the manipulation variable of the trigger switch (70) in the torque management mode until a predetermined condition is satisfied.

[0154] This aspect enables the shortening of the operation time, thereby improving user-friendliness.

[0155] In the electric tool system (100) according to the seventh aspect, which can be implemented in combination with any one of the first aspect to the sixth aspect, when the controller (3) finds that a predetermined condition is satisfied, it performs control to gradually change the speed of the motor (1) to the limit value (ωc) in a plurality of stages.

[0156] This aspect enables improvement in user-friendliness.

[0157] In the electric tool system (100) according to the eighth aspect, which can be implemented in combination with any one of the first to sixth aspects, the controller (3) performs control to change the speed of the motor (1) to a limit value (ωc) in a single step when a predetermined condition is found to be satisfied.

[0158] This aspect enables improvement in user-friendliness.

[0159] In the electric tool system (100) according to the ninth aspect, which can be implemented in combination with any one of the first to eighth aspects, the predetermined condition further includes a condition that the speed of the motor (1) is equal to or greater than a limit value.

[0160] This aspect enables improvement in user-friendliness.

[0161] In the electric tool system (100) according to the tenth aspect that can be implemented in combination with the ninth aspect, the controller (3) determines that the predetermined condition is not satisfied even when only one of the first condition and the second condition is satisfied and then only the other of the first condition and the second condition is satisfied. The first condition is a condition that the torque value (Tq1) reaches a threshold value. The second condition is a condition that the speed of the motor (1) becomes equal to or greater than the limit value (ωc).

[0162] This aspect enables improvement in user-friendliness.

[0163] In the electric tool system (100) according to the eleventh aspect which can be implemented in combination with any one of the first to tenth aspects, the controller (3) stops the motor (1) when the torque value (Tq1) reaches the upper limit value (TqL).

[0164] This aspect enables so-called "electronic clutch control".

[0165] The control method according to the twelfth aspect is a control method for controlling an electric tool system (100). The electric tool system (100) includes a motor (1), an output shaft (5), a transmission mechanism (4), an acquirer (31), and a trigger switch (70). The output shaft (5) can be coupled to a front-end tool (28). The transmission mechanism (4) transmits the driving force of the motor (1) to the output shaft (5). The acquirer (31) acquires a torque value (Tq1) related to the output torque provided by the front-end tool (28) based on the current flowing through the motor (1). The trigger switch (70) receives an operation command input by a user. The control method includes: controlling the motor (1) in a torque management mode, in which the motor (1) is controlled according to the operation command input through the trigger switch (70), and preventing the torque value (Tq1) acquired by the acquirer (31) from exceeding an upper limit value (TqL). The control method further includes: when it is found that a predetermined condition is satisfied in the torque management mode, regardless of the manipulation variable of the trigger switch (70), controlling the motor (1) to make the speed of the motor (1) become a predetermined limit value (ωc). The predetermined condition includes the condition that the torque value (Tq1) acquired by the acquirer (31) reaches a threshold value smaller than the upper limit value (TqL).

[0166] According to this aspect, before the motor (1) is stopped in response to the torque value (Tq1) reaching the upper limit value (TqL), the speed of the motor (1) is controlled to the limit value (ωc) in response to the torque value (Tq1) reaching the threshold value. That is, the motor (1) is not stopped until the speed of the motor (1) once approaches the limit value (ωc). This makes it possible to reduce the dispersion of the speed (ωe) of the motor (1) immediately before the motor (1) is stopped, thereby improving user-friendliness.

[0167] The program according to the thirteenth aspect is designed to cause one or more processors to perform the control method according to the twelfth aspect.

[0168] This aspect makes it possible to improve user-friendliness.

[0169] Description of reference numerals

[0170] 1 Motor

[0171] 3 Controller

[0172] 4 Transmission mechanism

[0173] 5 Output shaft

[0174] 28 Front-end tool

[0175] 31 Acquirer

[0176] 70 Trigger switch

[0177] 100 Electric tool system

[0178] Tq1 Torque value

[0179] TqL Upper limit value

[0180] ωc Limit value

[0181] ωe Speed

Claims

1. An electric tool system, comprising: A motor; An output shaft that can be coupled to a front-end tool; A transmission mechanism configured to transmit the driving force of the motor to the output shaft; An acquirer configured to acquire a torque value related to the output torque provided by the front-end tool based on the current flowing through the motor; A trigger switch configured to receive an operation command input by a user; And A controller having a torque management mode in which the controller controls the motor according to the operation command input through the trigger switch and prevents the torque value acquired by the acquirer from exceeding an upper limit value, wherein the controller is configured to, when it is found that a predetermined condition is satisfied in the torque management mode, control the motor to make the speed of the motor become a predetermined limit value regardless of the manipulation variable of the trigger switch, the predetermined condition includes the condition that the torque value acquired by the acquirer reaches a threshold value smaller than the upper limit value.

2. The electric tool system according to claim 1, further comprising an upper limit value setting unit configured to set one of a plurality of candidate upper limit values as the upper limit value.

3. The electric tool system according to claim 2, wherein the limit value is a value depending on the upper limit value set by the upper limit value setting unit.

4. The electric tool system according to claim 2 or 3, wherein the threshold value is a value depending on the upper limit value set by the upper limit value setting unit.

5. The electric tool system according to any one of claims 1 to 3, wherein the controller is configured to control the motor by vector control, and the acquirer is configured to acquire the torque value based on the torque current flowing through the motor.

6. The electric tool system according to any one of claims 1 to 3, wherein the controller is configured to control the speed of the motor according to the manipulation variable of the trigger switch in the torque management mode until the predetermined condition is satisfied.

7. The electric tool system according to any one of claims 1 to 3, wherein the controller is configured to, when it is found that the predetermined condition is satisfied, perform control to gradually change the speed of the motor to the limit value in a plurality of steps.

8. The electric tool system according to any one of claims 1 to 3, wherein the controller is configured to, when it is found that the predetermined condition is satisfied, perform control to change the speed of the motor to the limit value in a single step.

9. The electric tool system according to any one of claims 1 to 3, wherein the predetermined condition further includes the condition that the speed of the motor is equal to or greater than the limit value.

10. The electric tool system according to claim 9, wherein The controller is configured to determine that the predetermined condition is not satisfied even when only one of the first condition and the second condition is satisfied and then only the other of the first condition and the second condition is satisfied, where the first condition is a condition that the torque value reaches the threshold value, and the second condition is a condition that the speed of the motor becomes equal to or greater than the limit value.

11. The power tool system according to any one of claims 1 to 3, wherein the controller is configured to stop the motor from operating when the torque value reaches the upper limit value.

12. A control method for controlling an electric tool system, the electric tool system comprising: A motor; An output shaft that can be coupled to a front-end tool; A transmission mechanism configured to transmit the motive power of the motor to the output shaft; An acquirer configured to acquire a torque value related to the output torque provided by the front-end tool based on the current flowing through the motor; And a trigger switch configured to receive an operation command input by a user, the control method comprising: Controlling the motor in a torque management mode, in which the motor is controlled according to the operation command input through the trigger switch, and preventing the torque value acquired by the acquirer from exceeding an upper limit value; And When it is found that a predetermined condition is satisfied in the torque management mode, regardless of the manipulation variable of the trigger switch, controlling the motor so that the speed of the motor becomes a predetermined limit value, The predetermined condition includes a condition that the torque value acquired by the acquirer reaches a threshold value smaller than the upper limit value.

13. A non-transitory storage medium storing a program designed to cause one or more processors to perform the control method according to claim 12.

14. A computer program product including a computer program designed to cause a processor to perform the control method according to claim 12 when executed by the processor.

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