Electric work machine

Abstract

To provide an electrically-driven work machine which is superior in convenience.SOLUTION: An electrically-driven work machine comprises a motor, a current detector, and a controller. The controller sets a respective upper limit value of at least one correction amount for cases where at least one control parameter to be used in controlling the motor is corrected according to at least one correction amount. The controller calculates at least one correction amount using the respective upper limit values as the upper limit, if determined that a value of a driving current has exceeded a limit threshold value.SELECTED DRAWING: Figure 5A

Description

Technical Field

[0004] ,

[0006] , , , , , ,

[0005] , , , , , <00,00003> The present disclosure relates to a power-operated work machine.

Background Art

[0002] In the electric equipment described in Patent Document 1, when the drive current of the motor exceeds a preset current threshold value, the control parameter is corrected to suppress the drive current of the motor. As a result, when the motor receives an instantaneous large load, the drive current is suppressed while avoiding the stop of the motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above electric equipment, when the motor continuously receives a relatively large load, the drive current continues to be suppressed. As a result, the output torque becomes insufficient, and the work by the electric equipment may not be continued.

[0005] One aspect of the present disclosure provides a power-operated work machine with excellent convenience. <>

Means for Solving the Problems

[0006] An electric work machine in one aspect of the present disclosure comprises a motor, a current detection unit, and a control unit. The current detection unit is configured to detect the value of the motor's drive current. The control unit is configured to set upper limits for each of at least one correction amount when correcting at least one control parameter used to control the motor with at least one correction amount. The control unit is configured to determine whether the value of the drive current detected by the current detection unit exceeds a limit threshold. If the control unit determines that the value of the drive current exceeds the limit threshold, it is configured to calculate at least one correction amount, with each upper limit as the upper limit, so that the motor's drive current decreases. The control unit is configured to correct at least one control parameter with the calculated at least one correction amount. The control unit is configured to drive the motor based on at least one control parameter.

[0007] In the aforementioned electric work machine, an upper limit is set for the correction amount of each control parameter. When it is determined that the drive current value exceeds the limit threshold, the correction amount for each control parameter is calculated, using the respective upper limit as the upper limit. Then, each control parameter is corrected based on the calculated correction amount. Therefore, if the motor is subjected to a very large load instantaneously, the drive current can be suppressed to continue driving the motor. Furthermore, if the motor is subjected to a relatively large load continuously, the drive current can be increased as needed to avoid continuous suppression of the drive current. Thus, excellent convenience can be achieved. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the external appearance of an electric work machine according to the first embodiment. [Figure 2] This is a cross-sectional view showing the internal configuration of an electric work machine according to the first embodiment. [Figure 3] This is a block diagram showing the electrical configuration of an electric work machine according to the first embodiment. [Figure 4] This is a flowchart showing the procedure for the motor drive process according to the first embodiment. [Figure 5A] This is a part of a flowchart showing the procedure for output limiting processing according to the first embodiment. [Figure 5B] This is the remaining portion of the flowchart showing the procedure for output limiting processing according to the first embodiment. [Figure 6A] This is an example of a table showing the limit threshold, whether or not there is a limit upper limit, the upper limit of the rotational speed limit, and the upper limit of the duty cycle limit in the drill mode, clutch mode, high-speed gear mode, and low-speed gear mode according to the first embodiment. [Figure 6B] This is another example of a table showing the limit threshold, whether or not there is a limit upper limit, the upper limit of the rotational speed limit, and the upper limit of the duty cycle limit in the drill mode, clutch mode, high-speed gear mode, and low-speed gear mode according to the first embodiment. [Figure 6C] This is another example of a table showing the limit threshold, whether or not there is a limit upper limit, the upper limit of the rotational speed limit, and the upper limit of the duty cycle limit in the drill mode, clutch mode, high-speed gear mode, and low-speed gear mode according to the first embodiment. [Figure 7] This is a flowchart showing the output processing procedure according to the first embodiment. [Figure 8] This map shows the upper limit duty cycle and target rotational speed with respect to the trigger pull amount in the drill mode and clutch mode according to the first embodiment. [Figure 9] This is a map showing the reference duty cycle for the target rotational speed according to the first embodiment. [Figure 10] This is a time chart showing the time variation of the motor rotation speed, PWM duty cycle, and drive current according to the first embodiment. [Figure 11] This is a time chart showing the time variation of motor rotation speed, PWM duty cycle, and drive current for a reference example. [Figure 12] This is a flowchart showing the output processing procedure according to the second embodiment. [Figure 13] This is a map showing the target duty cycle for trigger pull amount in the drill mode and clutch mode according to the second embodiment. [Modes for carrying out the invention]

[0009] [Summary of Embodiment] An electric working machine in an embodiment may include a motor, a current detection unit, and a control unit.

[0010] The control unit may be configured to calculate a change amount from the difference between the value of the drive current detected by the current detection unit and a limit threshold value and a predetermined gain. Further, the control unit may be configured to calculate a correction amount by integrating the calculated change amount.

[0011] By calculating the change amount from the difference and the predetermined gain, particularly by multiplying the difference by the predetermined gain to calculate the change amount, when the motor instantaneously receives a very large load, the drive current can be instantaneously suppressed.

[0012] Also, by integrating the change amount to calculate the correction amount, when the motor continuously receives a relatively large load, the drive current can be intermittently suppressed. Furthermore, by setting an upper limit on the correction amount, when the torque becomes insufficient due to the suppression of the drive current, the drive current can be increased, preventing torque deficiency.

[0013] At least one control parameter may include the rotational speed of the motor, and / or the voltage applied to the motor, and / or the duty of the pulse voltage. By correcting the rotational speed of the motor, and / or the applied voltage, and / or the duty, the drive current can be suppressed.

[0014] The control unit may be configured to obtain a selection mode selected by the user from a plurality of operation modes. The control unit may be configured to change the upper limit value according to the obtained selection mode. The control unit may be configured to drive the motor based on the obtained selection mode. By changing the upper limit value according to the selection mode, better convenience can be realized.

[0015] Multiple operating modes may include a specific mode. The control unit may be configured not to set an upper limit depending on whether the selected mode is a specific mode. This allows the drive current to be continuously suppressed when the motor is subjected to a relatively large load for an extended period in the specific mode.

[0016] Multiple operating modes may include a drill mode for drilling holes in a workpiece and / or a clutch mode for fastening screws. The control unit may be configured to set the upper limit corresponding to the drill mode to a different value from the upper limit corresponding to the clutch mode.

[0017] When multiple operating modes include drill mode and clutch mode, there is a difference in the magnitude of the load the motor receives between drill mode and clutch mode. By changing the upper limit in drill mode to match the upper limit in clutch mode, greater convenience can be achieved.

[0018] The control unit may be configured to set the upper limit corresponding to the drill mode to be greater than the upper limit corresponding to the clutch mode. In drill mode, the motor is subjected to a greater load than in clutch mode. Therefore, by setting the upper limit in drill mode higher than the upper limit in clutch mode, the instantaneous large drive current can be appropriately suppressed in drill mode.

[0019] The control unit may be configured to set a limit threshold for drill mode to a different value from the limit threshold for clutch mode. By changing the limit threshold in drill mode from the limit threshold in clutch mode, greater convenience can be achieved.

[0020] The control unit may be configured to set the limit threshold corresponding to the drill mode to be smaller than the limit threshold corresponding to the clutch mode. By setting the limit threshold in drill mode to be smaller than the limit threshold in clutch mode, the difference between the drive current and the limit threshold increases, and the correction amount reaches the upper limit more quickly. Therefore, in drill mode, after limiting the output, the drive current can be increased quickly as needed.

[0021] An electric work machine in one embodiment may further include an output shaft, and / or a transmission unit, and / or a reduction ratio setting unit. The transmission unit may be configured to transmit the rotation of the motor to the output shaft at a first reduction ratio or a second reduction ratio greater than the first reduction ratio. The reduction ratio setting unit may be configured to set the reduction ratio of the transmission unit to the first reduction ratio or the second reduction ratio. The control unit may be configured to set the upper limit when the first reduction ratio is set by the reduction ratio setting unit to a different value from the upper limit when the second reduction ratio is set by the reduction ratio setting unit. When an electric work machine further includes an output shaft, a transmission unit, and a reduction ratio, greater convenience can be achieved by changing the upper limit when the first reduction ratio is set from the upper limit when the second reduction ratio is set.

[0022] The control unit may be configured such that the upper limit when the first reduction ratio is set by the reduction ratio setting unit is greater than the upper limit when the second reduction ratio is set by the reduction ratio setting unit.

[0023] By making the upper limit when the first reduction ratio is set greater than the upper limit when the second reduction ratio is set, instantaneous large drive currents can be appropriately suppressed when the first reduction ratio is set.

[0024] The control unit may be configured to set a limit threshold value different from the limit threshold value when a first reduction ratio is set by the reduction ratio setting unit compared to the limit threshold value when a second reduction ratio is set by the reduction ratio setting unit. By changing the limit threshold value when a first reduction ratio is set compared to the limit threshold value when a second reduction ratio is set, greater convenience can be achieved.

[0025] The control unit may be configured such that the limit threshold when a first reduction ratio is set by the reduction ratio setting unit is greater than the limit threshold when a second reduction ratio is set by the reduction ratio setting unit.

[0026] By making the limiting threshold when a first reduction ratio is set greater than the limiting threshold when a second reduction ratio is set, the drive current can be quickly increased as needed after output limiting when a first reduction ratio is set.

[0027] In some embodiments, the above-described features may be combined in any way. Also, in some embodiments, any of the above-described features may be omitted. Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0028] (1. First Embodiment) <1-1. Structure> The mechanical configuration of the electric work machine 10 according to this embodiment will be described with reference to Figures 1 and 2. In this embodiment, the electric work machine 10 is a driver drill.

[0029] The electric work machine 10 includes a housing 11. Various components are housed inside the housing 11. The housing 11 includes a motor housing 14. The motor housing 14 is located at the rear of the housing 11 (left side in the diagram).

[0030] The motor housing 14 houses the motor 50. The motor 50 is a three-phase brushless motor. The housing 11 houses the gear case 31 in front of the motor housing 14. The gear case 31 houses the reduction mechanism 30. The reduction mechanism 30 has an output shaft 7. Details of the reduction mechanism 30 will be described later. In this embodiment, the reduction mechanism 30 is an example of the transmission unit of this disclosure.

[0031] The electric work machine 10 is equipped with a chuck section 16. The chuck section 16 protrudes from the tip (right side in the diagram) of the housing 11. The chuck section 16 attaches the tool bit to the output shaft 7. The electric work implement 10 includes a torque selection unit 29. The torque selection unit 29 is located on the rear side of the chuck unit 16. The torque selection unit 29 is a rotatable annular member that is rotated by the user to set the magnitude of the torque (i.e., the tightening force) in the clutch mode described later.

[0032] The electric work machine 10 has a mode selection section 27 It includes a mode selection section. 27 It is located behind the torque selection unit 29. Mode selection unit 27 This is a rotatable annular member that is rotated by the user to set the operating mode. In this embodiment, the operating modes include a drill mode and a clutch mode. The drill mode is the operating mode for drilling holes in a workpiece. The clutch mode is the operating mode for tightening screws. When the clutch mode is selected, when the output torque reaches the torque value selected via the torque selection unit 29, the clutch is disengaged so that no torque exceeding the selected torque value is output.

[0033] The electric work implement 10 is equipped with a grip 12 for the user to hold by hand. The grip 12 protrudes downward from the housing 11. The grip 12 is equipped with a trigger 21. The trigger 21 is equipped with an operating part 21a that is pulled by the user holding the grip 12. The trigger 21 is also equipped with a speed setting part 21b which includes a sliding resistor.

[0034] The electric work implement 10 is equipped with a forward / reverse selector switch 22. The forward / reverse selector switch 22 is located above the trigger 21 and at the lower end of the housing 11. The forward / reverse selector switch 22 is a switch for switching the rotation direction of the motor 50 to the forward or reverse direction. The above-described operating modes may include a forward rotation mode and a reverse rotation mode. In the forward rotation mode, the motor 50 rotates in the forward direction, and in the reverse rotation mode, the motor 50 rotates in the reverse direction.

[0035] The electric work machine 10 is equipped with an illuminator 23. The illuminator 23 is located above the trigger 21 and in front of the lower end of the housing 11. The illuminator 23 includes one or more light-emitting diodes (hereinafter referred to as LEDs) and illuminates the area in front of the electric work machine 10 when the operating part 21a is pulled.

[0036] Furthermore, the electric work implement 10 is equipped with a connection part 28 located on the underside of the bottom of the grip 12. The connection part 28 is a sliding type, and the battery pack 160 is connected to it by sliding it in.

[0037] The battery pack 160 includes a battery 162 of a predetermined voltage. The battery 162 is a rechargeable secondary battery, such as a lithium-ion battery. Furthermore, a remaining capacity indicator 24 is provided on the upper surface of the bottom of the grip 12. The remaining capacity indicator 24 includes one or more LEDs and displays the remaining capacity of the battery 162.

[0038] Next, the details of the reduction mechanism 30 will be described with reference to Figure 2. The reduction mechanism 30 comprises internal gears 32A, 32B, and 32C, and a plurality of planetary gears 33A, a plurality of planetary gears 33B, and a plurality of planetary gears 33C. The internal gears 32A, 32B, and 32C are fixed to the inner circumferential surface of the gear case 31. The plurality of planetary gears 33A revolve within the internal gear 32A. The plurality of planetary gears 33B revolve within the internal gear 32B. The plurality of planetary gears 33C revolve within the internal gear 32C.

[0039] The internal gears 32A, 32B, and 32C are arranged in this order along the rotation axis of the motor 50, from the motor 50 to the front of the housing 11. Similarly, the multiple planetary gears 33A, 33B, and 33C are arranged in this order along the rotation axis of the motor 50, from the motor 50 to the front of the housing 11. The multiple planetary gears 33A, 33B, and 33C are each arranged at predetermined angular intervals around the rotation axis of the motor 50.

[0040] The reduction gear mechanism 30 comprises carriers 34A, 34B, and 34C. The carriers 34A, 34B, and 34C are arranged in this order along the rotation axis of the motor 50 and are rotatable around the rotation axis of the motor 50. Carrier 34A is positioned between a plurality of planetary gears 33A and a plurality of planetary gears 33B, rotatably supporting the plurality of planetary gears 33A and is fitted to the plurality of planetary gears 33B. Carrier 34B is positioned between a plurality of planetary gears 33B and a plurality of planetary gears 33C, rotatably supporting the plurality of planetary gears 33B and is fitted to the plurality of planetary gears 33C. Carrier 34C is positioned at the leading end of the plurality of planetary gears 33C and rotatably supports the plurality of planetary gears 33C.

[0041] Furthermore, multiple planetary gears 33A are mated with pinion gears 50A fixed to the rotating shaft of the motor 50. The output shaft 7 is fixed to the carrier 34C. Because the electric work machine 10 is equipped with a reduction mechanism 30, the rotation of the motor 50 is reduced in three stages by multiple planetary gears 33A to 33C and carriers 34A to 34C, and transmitted to the output shaft 7.

[0042] The reduction gear mechanism 30 also includes a slide ring 35. The slide ring 35 is movable within the gear case 31 along the rotation axis of the motor 50. The internal gear 32B is fixed to the slide ring 35.

[0043] The slide ring 35 is physically connected to the gear operating section 25. The gear operating section 25 is located on the upper surface of the housing 11. By moving the gear operating section 25 in the forward and backward direction, the slide ring 35 moves along the rotation axis of the motor 50.

[0044] When the user operates the gear operating unit 25 to move the slide ring 35 from the front position to the rear position, the multiple planetary gears 33B and the carrier 34A are connected by the internal gear 32B. As a result, the carriers 34A and 34B rotate together. Consequently, the reduction mechanism 30 reduces the rotation of the motor 50 in two stages using the multiple planetary gears 33A, 33C and the carriers 34A, 34C, and transmits it to the output shaft 7.

[0045] Therefore, when the gear operating unit 25 is moved backward, the rotation of the motor 50 is reduced by a first reduction ratio (i.e., two stages), causing the output shaft 7 to rotate at high speed. Conversely, when the gear operating unit 25 is moved forward, the rotation of the motor 50 is reduced by a second reduction ratio (i.e., three stages), causing the output shaft 7 to rotate at low speed. The second reduction ratio is greater than the first reduction ratio. Hereinafter, the mode in which the first reduction ratio is selected will be referred to as the high-speed gear mode, and the mode in which the second reduction ratio is selected will be referred to as the low-speed gear mode. In this embodiment, the gear operating unit 25 is an example of the reduction ratio setting unit of this disclosure.

[0046] Such speed switching is performed as appropriate by the user through the operation of the gear operating unit 25. When the motor 50 is rotating at a low speed in which it is reduced in three stages, the torque corresponding to the drive current is greater than when the motor 50 is rotating at a high speed in which it is reduced in two stages.

[0047] Next, the electrical configuration of the electric work machine 10 will be explained with reference to Figure 3. The electric work machine 10 is equipped with a position sensor 51. The position sensor 51 comprises three Hall ICs arranged to correspond to the stators of each phase of the motor 50. The Hall ICs output a rotation detection signal to a position detection circuit 71, which will be described later, each time the rotor of the motor 50 rotates by a predetermined angle.

[0048] The electric work machine 10 also includes a switch unit 200. The switch unit 200 includes a power switch 210a. The power switch 210a outputs a power-on signal to the power supply circuit 41 and the switch input determination unit 62, which will be described later, depending on whether the amount pulled by the operating part 21a of the trigger 21 is greater than or equal to a predetermined amount. The power switch 210a also outputs a power-off signal to the power supply circuit 41 and the switch input determination unit 62 depending on whether the amount pulled by the operating part 21a is less than a predetermined amount.

[0049] The switch unit 200 also includes a speed setting unit 21b. The speed setting unit 21b includes a sliding resistor and outputs a resistance value corresponding to the amount the operating unit 21a is pulled to the target value calculation unit 61.

[0050] The switch unit 200 also includes a forward / reverse switch 22. The forward / reverse switch 22 outputs a forward signal to the drive control unit 65 (described later) when the rotation direction is switched to the forward direction, and outputs a reverse signal to the drive control unit 65 when the rotation direction is switched to the reverse direction.

[0051] The mode selection unit 27 outputs an operation mode signal to the switch input determination unit 62 corresponding to the selected operation mode (specifically, drill mode or clutch mode). The gear operation unit 25 outputs a gear mode signal to the switch input determination unit 62 corresponding to the selected gear mode.

[0052] Furthermore, the electric work implement 10 includes a work implement circuit 100. The work implement circuit 100 includes a power supply circuit 41. The power supply circuit 41 is connected to a battery 162. When a power-on signal is input to the power supply circuit 41, it generates a predetermined power supply voltage Vcc from the input power and supplies the power supply voltage Vcc to various circuits within the work implement circuit 100, such as the control circuit 60.

[0053] The work machine circuit 100 includes a motor driver 42. The motor driver 42 is a three-phase full-bridge circuit including three switching elements on the high side and three switching elements on the low side. The motor driver 42 is connected between the battery 162 and the motor 50, and receives power from the battery 162 to supply current to the windings of each phase of the motor 50. Each switching element of the motor driver 42 is turned on or off in response to a control command output from the control circuit 60, which will be described later.

[0054] The work machine circuit 100 includes a current detection circuit 43. The current detection circuit 43 detects the value of the drive current flowing to the motor 50 and outputs a detection signal corresponding to the detected drive current value to the PWM generation unit 63.

[0055] The work machine circuit 100 includes a position detection circuit 71. The position detection circuit 71 detects the rotational position of the rotor of the motor 50 based on the rotation detection signal input from the position sensor 51. The position detection circuit 71 outputs a position signal corresponding to the detected rotational position to the control circuit 60.

[0056] The work machine circuit 100 includes a control circuit 60. The control circuit 60 includes a CPU 60a, ROM 60b, RAM 60c, and I / O, etc. The various functions of the control circuit 60 are realized by the CPU 60a executing a program stored in a non-transitional physical recording medium. In this embodiment, ROM 60b corresponds to the non-transitional physical recording medium. By executing this program, a method corresponding to the program is executed. Note that some or all of the functions executed by the CPU 60a may be configured in hardware by one or more ICs, etc. Furthermore, the control circuit 60 may consist of a single microcomputer or multiple microcomputers. In this embodiment, the control circuit 60 corresponds to an example of a control unit.

[0057] The control circuit 60 includes, as various functions, a target value calculation unit 61, a switch input determination unit 62, a PWM generation unit 63, a rotation speed calculation unit 64, a drive control unit 65, and a display control unit 66. In this embodiment, the control circuit 60 includes all of the above-mentioned functions, but in another embodiment, any of the above-mentioned functions may be omitted.

[0058] The target value calculation unit 61 calculates the target rotational speed of the motor 50 based on the input resistance value. The switch input determination unit 62 determines whether the power is on or off based on the input power-on signal or power-off signal, and outputs the determination result to the PWM generation unit 63 and the display control unit 66. The switch input determination unit 62 also determines the selected operating mode based on the input operating mode signal, and outputs the determination result to the PWM generation unit 63 and the display control unit 66. The switch input determination unit 62 also determines the selected gear mode based on the input gear mode signal, and outputs the determination result to the PWM generation unit 63 and the display control unit 66.

[0059] The rotation speed calculation unit 64 calculates the rotation speed of the motor 50 based on the position signal input from the position detection circuit 71 and outputs the calculation result to the PWM generation unit 63. The PWM generation unit 63 generates a PWM signal based on the power on / off determination result, the operation mode determination result, the gear mode determination result, the detection signal, and the calculation result. The PWM generation unit 63 outputs the generated PWM signal to the drive control unit 65.

[0060] The drive control unit 65 generates a control command based on the PWM signal output from the PWM generation unit 63 and the forward or reverse signal output from the forward / reverse switch 22. The control command instructs each switch included in the motor driver 42 to turn on or off. The drive control unit 65 outputs the generated control command to the motor driver 42. As a result, pulse voltages based on the PWM signal are applied to the windings of each phase of the motor 50.

[0061] The electric work machine 10 also includes a mode display unit 130. The mode display unit 130 includes at least one LED. The work machine circuit 100 also includes a display circuit 72. The display control unit 66 notifies the operating mode via the display circuit 72 using the mode display unit 130, based on the result of the input operating mode determination. That is, the display control unit 66 turns the mode display unit 130 on, blinks, or turns it off according to the operating mode. The display control unit 66 also turns the illuminator 23 on, blinks, or turns it off via the display circuit 72, based on the input power on / off determination result, the operating mode determination result, and the gear mode determination result.

[0062] <1-2. Processing> <1-2-1. Motor drive processing> Next, the motor drive process performed by the control circuit 60 will be explained using the flowchart in Figure 4. The control circuit 60 starts this process when the power is turned on and it starts up.

[0063] First, in S10, the motor 50 is stopped. Next, in S20, the current power limit is cleared; that is, the power limit is set to zero. The power limit includes the rotational speed limit and / or duty cycle limit, which will be described later.

[0064] Next, in S30, it is determined whether the operating part 21a of the trigger 21 has been pulled by a predetermined amount or more. If it is determined that the operating part 21a has been pulled by a predetermined amount or more, the process proceeds to S40. If it is determined that the operating part 21a has not been pulled by a predetermined amount or more, the process returns to S10.

[0065] In S40, the input operating mode and gear mode are acquired. In this embodiment, the operating mode is either drill mode or clutch mode, and the gear mode is either high-speed gear mode or low-speed gear mode. If the operating mode includes forward rotation mode and reverse rotation mode in addition to drill mode and clutch mode, then either drill mode or clutch mode and either forward rotation mode or reverse rotation mode are acquired as the operating mode.

[0066] Next, in S50, the amount of pull on the operating unit 21a is obtained based on the resistance value output from the speed setting unit 21b. Next, in S60, output limiting processing is performed. Output limiting processing is a process that limits the output of motor 50 in order to prevent the drive current from increasing excessively and damaging the motor 50 or the work equipment circuit 100. Details of the output limiting processing will be described later.

[0067] Next, in S70, output processing is performed. That is, the output of motor 50 is controlled based on the output limit amount calculated in the output limit processing. Details of the output processing will be described later. After processing in S70, the process returns to S30.

[0068] <1-2-2. Output Limiting Process> Next, the output limiting process performed by the control circuit 60 will be explained with reference to the flowcharts in Figures 5A and 5B.

[0069] First, S100 obtains the current drive current value (hereinafter referred to as the drive current value) Inow. Next, in S110, the difference ΔI between Inow, acquired in S100, and the limit threshold Ith is calculated. The limit threshold Ith is set according to the operating mode and gear mode and is stored in ROM 60b. Figures 6A and 6B show examples of limit threshold Ith in drill mode, clutch mode, high-speed gear mode, and low-speed gear mode, respectively. Figures 6A and 6B show examples where the operating mode does not include forward rotation mode and reverse rotation mode, and four sets of various parameters are set according to the combination of the four modes. Figure 6C shows an example where the operating mode includes forward rotation mode and reverse rotation mode. In Figure 6C, eight sets of various parameters are set according to the combination of forward rotation drill mode, reverse rotation drill mode, forward rotation clutch mode, reverse rotation clutch mode, high-speed gear mode, and low-speed gear mode. The various parameters include the limit threshold Ith, the presence or absence of an upper limit (described later), the upper limit L_smax for the rotation speed limit, and the upper limit L_dmax for the duty cycle limit.

[0070] As shown in Figures 6A and 6B, the limit threshold Ith in drill mode is different from the limit threshold Ith in clutch mode. Specifically, the limit threshold Ith in drill mode is smaller than the limit threshold Ith in clutch mode. Also, as shown in Figure 6C, the limit threshold Ith in drill mode in the forward rotation direction is different from the limit threshold Ith in drill mode in the reverse rotation direction. Specifically, the limit threshold Ith in drill mode in the forward rotation direction is smaller than the limit threshold Ith in the reverse rotation direction.

[0071] Furthermore, as shown in Figures 6A and 6B, in drill mode, the limit threshold Ith in high-speed gear mode is different from the limit threshold Ith in low-speed gear mode. Specifically, in drill mode, the limit threshold Ith in high-speed gear mode is greater than the limit threshold Ith in low-speed gear mode. As shown in Figure 6C, in drill mode in the forward rotation direction, the limit threshold Ith in high-speed gear mode is different from the limit threshold Ith in low-speed gear mode. Specifically, in drill mode in the forward rotation direction, the limit threshold Ith in high-speed gear mode is greater than the limit threshold Ith in low-speed gear mode.

[0072] Next, in S120, the change in the rotational speed limit ΔL_sp and the change in the duty cycle limit ΔL_du are calculated. Specifically, the difference ΔI calculated in S110 is multiplied by the speed gain Gs to calculate the change in the rotational speed limit ΔL_sp. Also, the difference ΔI is multiplied by the duty cycle gain Gd to calculate the change in the duty cycle limit ΔL_du. If the current drive current value Inow is greater than the limit threshold Ith, the change in the rotational speed limit ΔL_sp and the change in the duty cycle limit ΔL_du will be positive values ​​to further limit the output. On the other hand, if the current drive current Inow is less than the limit threshold Ith, the change in the rotational speed limit ΔL_sp and the change in the duty cycle limit ΔL_du will be negative values ​​to relax the output limit.

[0073] Next, in S130, the current rotation speed limit L_sp is updated by adding the change amount ΔL_sp calculated in S20. In other words, the rotation speed limit L_sp corresponds to the cumulative value of the change amount ΔL_sp.

[0074] Next, in S140, it is determined whether the rotation speed limit L_sp, which was updated in S130, is less than 0 (i.e., a negative value). If it is determined that the rotation speed limit L_sp is 0 or greater, the process proceeds to S150. If it is determined that the rotation speed limit L_sp is less than 0, the process proceeds to S145.

[0075] In S145, the rotation speed limit L_sp is set to 0, and the process proceeds to S150. In S150, it is determined whether or not there is an upper limit to the rotational speed limit L_sp, that is, whether or not an upper limit is set for the rotational speed limit L_sp. Whether or not there is an upper limit to the rotational speed limit L_sp is set according to the operating mode and gear mode and is stored in ROM 60b. Figures 6A and 6B show examples of whether or not there is an upper limit in the drill mode, clutch mode, high-speed gear mode, and low-speed gear mode, respectively. Figure 6C also shows examples of whether or not there is an upper limit in the forward rotation drill mode, reverse rotation drill mode, forward rotation clutch mode, reverse rotation clutch mode, high-speed gear mode, and low-speed gear mode. In the example shown in Figure 6A, all mode combinations have an upper limit. On the other hand, in the example shown in Figure 6B, the combination of drill mode and high-speed gear mode does not have an upper limit, while all other mode combinations have an upper limit. In the example shown in Figure 6C, the combination of forward rotation drill mode and high-speed gear mode does not have an upper limit, while all other mode combinations have an upper limit. Whether or not there is a limit is set according to the operating mode and gear mode, as well as according to the type of electric work implement 10. Figures 6A, 6B, and 6C each show the settings for different types of electric work implements 10. In the example shown in Figure 6B, the drill mode corresponds to an example of a specific mode, and in the example shown in Figure 6C, the drill mode in the forward rotation direction corresponds to an example of a specific mode.

[0076] If it is determined in S150 that there is an upper limit to the rotation speed limit L_sp, the process proceeds to S160. If it is determined that there is no upper limit to the rotation speed limit L_sp, the process proceeds to S180.

[0077] In S160, it is determined whether the rotational speed limit L_sp, which was updated in S130, is greater than or equal to the upper limit L_smax of the rotational speed limit. The upper limit L_smax of the rotational speed limit is set according to the operating mode and gear mode and is stored in ROM 60b. Figures 6A and 6B show examples of the upper limit L_smax of the rotational speed limit in drill mode, clutch mode, high-speed gear mode, and low-speed gear mode, respectively. Figure 6C shows examples of the upper limit L_smax of the rotational speed limit in drill mode in forward rotation, drill mode in reverse rotation, clutch mode in forward rotation, clutch mode in reverse rotation, high-speed gear mode, and low-speed gear mode.

[0078] As shown in Figures 6A and 6B, the upper limit L_smax of the rotational speed limit in drill mode is different from the upper limit L_smax of the rotational speed limit in clutch mode. Specifically, the upper limit L_smax of the rotational speed limit in drill mode is greater than the upper limit L_smax of the rotational speed limit in clutch mode. Also, as shown in Figure 6C, the upper limit L_smax of the rotational speed limit in drill mode in the forward rotation direction is different from the upper limit L_smax of the rotational speed limit in drill mode in the reverse rotation direction. Specifically, the upper limit L_smax of the rotational speed limit in drill mode in the forward rotation direction is greater than the upper limit L_smax of the rotational speed limit in drill mode in the reverse rotation direction.

[0079] If, in S160, it is determined that the rotation speed limit L_sp is greater than or equal to the upper limit L_smax, the process proceeds to S170. In S170, an upper limit L_smax is set for the rotational speed limit L_sp. That is, even if the drive current Inow remains higher than the limit threshold Ith, the limit L_sp will not increase further once it reaches the upper limit L_smax.

[0080] This allows for suppression of instantaneous suppression of the drive current when the motor 50 is subjected to a very large load instantaneously, and allows for an increase in the drive current as needed when the motor 50 is subjected to a relatively large load continuously.

[0081] For example, when drilling a hole in wood with the electric work tool 10, if the tool bit hits a knot in the wood, the motor 50 receives a very large load instantaneously, and its output is limited. As the drilling continues and the hole gets deeper, the motor 50 continues to receive a relatively large load, although smaller than when it hit a knot. At this time, if the drive current of the motor 50 is continuously suppressed, it will not be able to output the necessary torque, and the work will stop. In contrast, by setting the limit amount L_sp to less than or equal to the upper limit L_smax, the drive current of the motor 50 is increased as needed, and the work stops. After processing S170, the process proceeds to S180.

[0082] On the other hand, if it is determined in S160 that the rotation speed limit L_sp is less than the upper limit L_smax, the process proceeds to S180. In S180, the duty cycle limit L_du is set to: S120 The change amount ΔL_du calculated in the previous step is added to update the duty cycle limit L_du. In other words, the duty cycle limit L_du corresponds to the cumulative value of the change amounts ΔL_du.

[0083] Next, in S190, it is determined whether the duty cycle limit L_du, which was updated in S180, is less than 0 (i.e., a negative value). If it is determined that the duty cycle limit L_du is 0 or greater, the process proceeds to S210. If it is determined that the duty cycle limit L_du is less than 0, the process proceeds to S200.

[0084] In S200, the duty cycle limit L_du is set to 0, and the process proceeds to S210. In S210, it is determined whether or not an upper limit is set for the duty cycle limit L_du. Similar to the presence or absence of an upper limit for the rotational speed limit L_sp, the presence or absence of an upper limit for the duty cycle limit L_du is set according to the operating mode and gear mode and stored in ROM 60b. In this embodiment, as shown in Figures 6A, 6B, and 6C, the presence or absence of an upper limit for the duty cycle limit L_du coincides with the presence or absence of an upper limit for the rotational speed limit L_sp, but the presence or absence of an upper limit for the duty cycle limit L_du may be set independently of the presence or absence of an upper limit for the rotational speed limit L_sp.

[0085] In S210, if it is determined that there is an upper limit on the duty cycle limit L_du, S220 Proceed to the next step. If it is determined that there is no upper limit on the duty cycle limit L_du, terminate this process.

[0086] In S220, it is determined whether the duty cycle limit L_du, updated in S180, is greater than or equal to the duty cycle limit L_dmax. The duty cycle limit L_dmax is set according to the operating mode and gear mode and is stored in ROM60b. Figures 6A and 6B show examples of the duty cycle limit L_dmax in drill mode, clutch mode, high-speed gear mode, and low-speed gear mode, respectively. Figure 6C shows examples of the duty cycle limit L_dmax in forward-rotating drill mode, reverse-rotating drill mode, forward-rotating clutch mode, reverse-rotating clutch mode, high-speed gear mode, and low-speed gear mode.

[0087] As shown in Figures 6A and 6B, the upper limit L_dmax of the duty cycle limit in drill mode is different from the upper limit L_dmax of the duty cycle limit in clutch mode. Specifically, the upper limit L_dmax of the duty cycle limit in drill mode is different from that in clutch mode. DutyIt is greater than the upper limit L_dmax of the duty cycle limit. Also, as shown in Figure 6C, the upper limit L_dmax of the duty cycle limit in the forward rotation drill mode is different from the upper limit L_dmax of the duty cycle limit in the reverse rotation drill mode. Specifically, the upper limit L_dmax of the duty cycle limit in the forward rotation drill mode is different from the upper limit L_dmax of the duty cycle limit in the reverse rotation drill mode. Duty It is greater than the upper limit L_dmax of the limit.

[0088] Furthermore, in drill mode, the upper limit L_dmax of the duty cycle limit in high-speed gear mode is different from the upper limit L_dmax of the duty cycle limit in low-speed gear mode. Specifically, in drill mode, the upper limit L_dmax of the duty cycle limit in high-speed gear mode is different from the upper limit L_dmax in low-speed gear mode. Duty It is greater than the upper limit L_dmax of the limit.

[0089] If, in S220, it is determined that the duty cycle limit L_du is greater than or equal to the upper limit L_dmax, the process proceeds to S230. In S230, an upper limit L_dmax is set for the duty cycle limit L_du. That is, even if the drive current Inow remains above the limit threshold Ith for an extended period, the limit L_du will not increase further once it reaches the upper limit L_dmax. This allows for suppression of instantaneous increases in drive current when the motor 50 is subjected to a very large load instantaneously, and allows for increasing the drive current as needed when the motor 50 is subjected to a relatively large load continuously. After processing in S230, this process is terminated.

[0090] on the other hand, S220 If it is determined that the duty cycle limit L_du is less than the upper limit L_dmax, this process is terminated. <1-2-3. Output Processing> Next, the output processing performed by the control circuit 60 will be explained with reference to the flowchart in Figure 7.

[0091] First, in S300, the upper duty cycle Max_du is obtained based on the mode acquired in S40, the trigger pull amount acquired in S50, and the first map. The first map shows the upper duty cycle Max_du according to the trigger pull amount in drill mode and clutch mode, respectively, and is stored in ROM60b. Figure 8 shows an example of the first map according to this embodiment.

[0092] Next, in S310, the target rotational speed Tg_sp is obtained based on the mode acquired in S40, the trigger pull amount acquired in S50, and the second map. The second map shows the target rotational speed Tg_sp corresponding to the trigger pull amount in both the drill mode and the clutch mode, and is stored in the ROM 60b. Figure 8 shows an example of the second map according to this embodiment.

[0093] In S310, the target rotational speed Tg_sp obtained from the second map is corrected by subtracting the rotational speed limit L_sp. The rotational speed limit L_sp is a value calculated in the output limiting process.

[0094] Next, in S320, the reference duty cycle of the PWM signal is calculated according to the corrected target rotation speed Tg_sp acquired in S310. Bs_du This is obtained. Specifically, the reference duty cycle Bs_du is obtained using a third map that shows the correspondence between the target rotational speed Tg_sp and the reference duty cycle Bs_du. Figure 9 shows an example of the third map according to this embodiment.

[0095] Next, in steps S330 to S360, in order to perform feedback control of the rotational speed of the motor 50 based on proportional-integral control, the proportional correction amount Off_p and the integral correction amount Off_i, which are feedback correction amounts, are calculated.

[0096] First, in S330, the speed difference ΔSP between the target rotational speed Tg_sp and the current actual rotational speed Now_sp is calculated. Next, in S340, the proportional correction amount Off_p is calculated by multiplying the speed difference ΔSP calculated in S330 by the proportional gain Gp.

[0097] Next, in S350, the speed difference ΔSP calculated in S330 is added to the current cumulative difference D_int to update the cumulative difference D_int. Next, in S360, the integral correction amount Off_i is calculated by multiplying the cumulative difference D_int, which was updated in S350, by the integral gain Gi.

[0098] Next, in S370, the baseline duty cycle obtained in S320 Bs_du Then, the proportional correction amount Off_p calculated in S340 and the integral correction amount Off_i calculated in S360 are added to calculate the set duty cycle Set_du.

[0099] Next, in S380, it is determined whether the set duty cycle Set_du calculated in S370 is greater than the upper duty cycle Max_du obtained in S300. If it is determined that the set duty cycle Set_du is less than or equal to the upper duty cycle Max_du, the process proceeds to S400. If it is determined that the set duty cycle Set_du is greater than the upper duty cycle Max_du, the process proceeds to S390.

[0100] In S390, the upper duty cycle Max_du is set to the set duty cycle Set_du. This prevents the drive current from exceeding the protection threshold. Next, in S400, the output duty cycle Out_du is calculated by subtracting the duty cycle limit L_du from the set duty cycle Set_du. The duty cycle limit L_du is a value calculated during the output limiting process. Then, a control command based on the output duty cycle Out_du is generated and output to the motor driver 42.

[0101] <1-3. Operation> Figure 10 shows the actual rotational speed of the motor 50, the duty cycle of the PWM signal, and the time change of the drive current when the motor drive process according to this embodiment is executed.

[0102] In Figure 10, at time t1, the motor 50 is subjected to a load, and its actual rotational speed begins to decrease. In response, the drive current begins to increase in order to bring the actual rotational speed closer to the target rotational speed. At time t2, when the drive current exceeds the limit threshold, output limiting is initiated, the duty cycle decreases from 100%, and the drive current decreases accordingly. Furthermore, from time t3 onwards, the output is continuously limited.

[0103] Then, at time t4, the motor 50 is subjected to a very large load, causing the actual rotational speed to drop sharply and the drive current to rise sharply. Consequently, the output limit increases, the duty cycle drops to 50%, and the drive current decreases significantly. As the output limit increases, the output limit reaches its upper limit, and the duty cycle remains constant at 50%, never dropping below 50%.

[0104] Then, at time t5, a drive current greater than what is being suppressed is required, the duty cycle increases, and the drive current increases. In other words, while suppressing a rapid increase in drive current, the drive current increases as needed.

[0105] For comparison with this embodiment, Figure 11 shows the rotational speed, PWM signal duty cycle, and drive current time variation of the motor 50 according to the reference example. In the reference example, no limiting threshold is set and no output limiting processing is performed.

[0106] In Figure 11, as the motor 50 receives a load and its actual rotational speed begins to decrease, the drive current starts to increase. Then, at time t10, when the drive current exceeds the protection threshold, the duty cycle drops sharply from 100% to 0%, the drive current becomes zero, and the motor 50 stops. The following is a supplement regarding the correspondence between the claims and the configuration of this embodiment. The "target value" in the claims corresponds to the target rotational speed Tg_sp in motor control. The "reduction amount" in the claims corresponds to the rotational speed limit L_sp which is subtracted from the target rotational speed Tg_sp for output limiting, or the duty cycle limit L_du which is subtracted from the set duty cycle Set_du. The "upper limit" in the claims corresponds to the upper limit L_smax of the rotational speed limit, which is set as the maximum value of the rotational speed limit L_sp, or the upper limit L_dmax of the duty cycle limit, which is set as the maximum value of the duty cycle limit L_du.

[0107] <1-4. Effects> The first embodiment described in detail above provides the following effects. (1) Upper limits are set for the rotational speed and duty cycle limits, and when it is determined that the drive current value exceeds the limit threshold, the rotational speed and duty cycle limits are calculated using the upper limits as the upper limit. Then, the target rotational speed and output duty cycle are corrected based on the calculated rotational speed and duty cycle limits. Therefore, if the motor 50 is momentarily subjected to a very large load, the drive current can be suppressed and the motor 50 can continue to be driven. Furthermore, if the motor 50 is continuously subjected to a relatively large load, the drive current can be increased as needed to avoid continuous suppression of the drive current.

[0108] (2) By calculating the limit by accumulating the changes in the rotational speed and duty cycle limits, the drive current can be suppressed instantaneously when the motor 50 is subjected to a very large load instantaneously. In addition, the drive current can be increased as needed when the motor 50 is subjected to a relatively large load continuously.

[0109] (3) By setting the upper limits of the rotational speed and duty cycle in drill mode to be greater than the upper limits of the rotational speed and duty cycle in clutch mode, instantaneous large drive currents can be appropriately suppressed in drill mode.

[0110] (4) The upper limits of the rotational speed and duty cycle in the forward rotation drill mode are set higher than the upper limits of the rotational speed and duty cycle in the reverse rotation drill mode. The reverse rotation drill mode is used to remove the drill bit from a hole after drilling in the forward rotation drill mode. Therefore, it is not expected that a continuous load will be applied to the motor 50 in the reverse rotation drill mode. Consequently, in the reverse rotation drill mode, work efficiency can be increased by reducing the upper limits of the rotational speed and duty cycle.

[0111] (5) The limit threshold in drill mode or forward rotation drill mode is set lower than the limit threshold in clutch mode or reverse rotation drill mode. This increases the difference between the drive current and the limit threshold, causing the rotational speed and duty cycle limits to reach their upper limits more quickly. Therefore, in drill mode or forward rotation drill mode, the drive current can be increased quickly as needed after the output limit has been applied.

[0112] (6) By making the upper limit of the duty cycle limit in high-speed gear mode greater than the upper limit of the duty cycle limit in low-speed gear mode, instantaneous large drive currents can be appropriately suppressed in high-speed gear mode.

[0113] (7) By making the limit threshold in high-speed gear mode greater than the limit threshold in low-speed gear mode, the drive current can be quickly increased as needed after limiting the output in high-speed gear mode.

[0114] (8) When the operating mode is drill mode and high-speed gear mode, or drill mode in the forward rotation direction and high-speed gear mode, there is no upper limit set for the rotational speed and duty cycle. This allows the drive current to be continuously suppressed when the motor 50 is continuously subjected to a relatively large load in drill mode and high-speed gear mode, or drill mode in the forward rotation direction and high-speed gear mode.

[0115] (2. Second Embodiment) <2-1. Differences from the First Embodiment> The second embodiment has the same basic configuration as the first embodiment, so the differences will be explained below. Note that the same reference numerals as in the first embodiment indicate the same components, and refer to the preceding description.

[0116] In the first embodiment described above, the rotational speed of the motor 50 was controlled by feedback. In contrast, the second embodiment differs from the first embodiment in that the rotational speed of the motor 50 is controlled without feedback. That is, in the second embodiment, the output processing of the motor drive process differs from that of the first embodiment.

[0117] Furthermore, in the second embodiment, in the output limiting process, only the duty cycle limit L_du is calculated, and the rotation speed limit L_sp does not need to be calculated. The target value calculation unit 61 calculates the target duty cycle Tg_du based on the resistance value output from the speed setting unit 21b and the operation mode determination result output from the switch input determination unit 62. Also, in the second embodiment, the function of the rotation speed calculation unit 64 is not required.

[0118] <2-2. Output Processing> Next, the output processing performed by the control circuit 60 will be explained with reference to the flowchart in Figure 12.

[0119] First, in S500, the target duty cycle Tg_du is obtained based on the mode acquired in S40, the trigger pull amount acquired in S50, and the fourth map. The fourth map shows the target duty cycle Tg_du corresponding to the trigger pull amount in drill mode and clutch mode, respectively, and is stored in ROM 60b. Figure 13 shows an example of the fourth map according to this embodiment.

[0120] Next, in S510, it is determined whether the target duty cycle Tg_du obtained in S500 is greater than the currently set setting duty cycle Set_du. If it is determined that the target duty cycle Tg_du is less than or equal to the setting duty cycle Set_du, the process proceeds to S520. In S520, the target duty cycle Tg_du is set to the setting duty cycle Set_du, and the process proceeds to S540.

[0121] On the other hand, if in S510 it is determined that the target duty cycle Tg_du is greater than the set duty cycle Set_du, the process proceeds to S530. In S530, the set duty cycle Set_du is updated by adding the increment duty cycle Inc_du to the set duty cycle Set_du, and the process proceeds to S540. The increment duty cycle Inc_du is a predetermined fixed value.

[0122] In S540, the output duty cycle Out_du is calculated by subtracting the duty cycle limit L_du from the set duty cycle Set_du. The duty cycle limit L_du is a value calculated during the output limiting process. Then, a control command based on the output duty cycle Out_du is generated and output to the motor driver 42. The following supplements will be made regarding the correspondence between the claims and the configuration of this embodiment. The "target value" in the claims corresponds to the target duty cycle Tg_du in motor control. The "reduction amount" in the claims corresponds to the duty cycle limit L_du which is subtracted from the set duty cycle Set_du. The "upper limit" in the claims corresponds to the upper limit L_dmax of the duty cycle limit, which is set as the maximum value of the duty cycle limit L_du.

[0123] <2-3. Effects> The second embodiment described in detail above achieves the effects (3) to (6) of the first embodiment described above, and further achieves the following effects.

[0124] (9) An upper limit is set for the duty cycle limit, and when it is determined that the drive current value exceeds the limit threshold, the duty cycle limit is calculated with the upper limit as the upper limit. Then, the output duty cycle is corrected based on the calculated duty cycle limit. Therefore, if the motor 50 is momentarily subjected to a very large load, the drive current can be suppressed and the motor 50 can continue to be driven. Furthermore, if the motor 50 is continuously subjected to a relatively large load, the drive current can be increased as needed to avoid the drive current being continuously suppressed.

[0125] (10) By calculating the limit by accumulating the change in the duty cycle limit, the drive current can be suppressed instantaneously when the motor 50 is subjected to a very large load instantaneously. Also, when the motor 50 is subjected to a relatively large load continuously, the drive current can be increased as needed.

[0126] (3. Other Embodiments) Although embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be implemented in various modified forms.

[0127] (3a) In the above embodiment, the electric work machine 10 has two operating modes, but it may have three or more operating modes. Also, the electric work machine 10 has two gear modes, but it may have three or more gear modes. Furthermore, the multiple operating modes may include an operating mode in which no upper limit value of the limit is set, and the multiple gear modes may include a gear mode in which no upper limit value of the limit is set.

[0128] (3b) In the above embodiment, the motor 50 was controlled by PWM control, but the motor 50 may be controlled by pulse voltage amplitude modulation (PAM) control, not limited to PWM control. When the motor 50 is controlled by PAM control, the control parameters for controlling the motor 50 include the applied voltage applied to the motor 50. In this case, instead of the duty cycle limit L_du, the applied voltage limit is calculated, and instead of the upper limit of the duty cycle limit L_du, an upper limit of the applied voltage limit is set. Then, the applied voltage limit is calculated so that it is less than or equal to the set upper limit.

[0129] (3c) The electric work implement 10 is not limited to a driver drill. The electric work implement 10 can be any electric work implement equipped with a drill bit. For example, the electric work implement 10 can be a power tool such as a reciprocating saw, jigsaw, or hammer drill, or a gardening tool such as a brush cutter.

[0130] (3d) Multiple functions of one component in the above embodiment may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, some of the configuration of the above embodiment may be omitted. Also, at least some of the configuration of the above embodiment may be added to or replaced with the configuration of other above embodiments. [Explanation of Symbols]

[0131] 7…Output shaft, 10…Electric work implement, 21…Trigger, 21a…Operation unit, 21b…Speed ​​setting unit, 22…Forward / reverse switch, 25…Gear operation unit, 27a…Mode selection unit, 29…Torque selection unit, 30…Reduction mechanism, 41…Power supply circuit, 42…Motor driver, 43…Current detection circuit, 50…Motor, 51…Position sensor, 71…Position detection circuit, 60…Control circuit.

Claims

1. A motor configured to drive a tool and having a protective stop function, wherein the protective stop function is a function that stops the motor by cutting off the power supply to the motor when the magnitude of the drive current of the motor exceeds a protection threshold, and A current detection unit configured to repeatedly detect a drive current value corresponding to the magnitude of the aforementioned drive current, A control unit configured to control the applied voltage or rotational speed of the motor according to a target value of the applied voltage or rotational speed of the motor set based on a command value from the user, and to repeatedly perform an output limiting process that reduces the target value of the applied voltage or rotational speed during the control of the applied voltage or rotational speed, The output limiting process includes (i) increasing the amount of decrease in the target value as the cumulative amount of the value obtained by subtracting a limiting threshold from the drive current value detected by the current detection unit increases; (ii) resetting the cumulative amount when the cumulative amount becomes a negative value; and (iii) setting the amount of decrease in the target value to the upper limit if the amount of decrease exceeds a set upper limit, wherein the limiting threshold is a threshold set to start limiting the motor output before the protection stop function is activated, and the upper limit is the maximum value of the decrease amount set to suppress the stopping of work due to a decrease in the motor output. Electric work equipment.

2. The control unit is configured to calculate a change amount from the difference between the drive current value detected by the current detection unit during the rotation of the motor and the limit threshold, and from a predetermined gain, and to calculate the decrease amount by integrating the calculated change amounts. The electric work machine according to claim 1.

3. The control unit is configured to acquire a selected mode chosen by the user from a plurality of operating modes, change the upper limit value according to the acquired selected mode, and drive the motor based on the acquired selected mode. The electric work machine according to claim 1 or 2.

4. The aforementioned plurality of operating modes include a specific mode, The control unit is configured not to set the upper limit value depending on whether the selected mode is the specific mode. The electric work machine according to claim 3.

5. The aforementioned plurality of operating modes include a drill mode for drilling holes in a workpiece and a clutch mode for fastening screws. The control unit is configured to set the upper limit corresponding to the drill mode to a value different from the upper limit corresponding to the clutch mode. The electric work machine according to claim 3 or 4.

6. The control unit is configured such that the upper limit corresponding to the drill mode is greater than the upper limit corresponding to the clutch mode. The electric work machine according to claim 5.

7. The control unit is configured to set the limit threshold corresponding to the drill mode to a value different from the limit threshold corresponding to the clutch mode. The electric work machine according to claim 5 or 6.

8. The control unit is configured to make the limit threshold corresponding to the drill mode smaller than the limit threshold corresponding to the clutch mode. The electric work machine according to claim 7.

9. Output shaft and, A transmission unit configured to transmit the rotation of the motor to the output shaft at a first reduction ratio or a second reduction ratio greater than the first reduction ratio, The system further comprises a reduction ratio setting unit configured to set the reduction ratio of the transmission unit to the first reduction ratio or the second reduction ratio, The control unit is configured to set the upper limit value when the first reduction ratio is set by the reduction ratio setting unit to a value different from the upper limit value when the second reduction ratio is set by the reduction ratio setting unit. An electric work machine according to any one of claims 1 to 8.

10. The control unit is configured such that the upper limit when the first reduction ratio is set by the reduction ratio setting unit is greater than the upper limit when the second reduction ratio is set by the reduction ratio setting unit. The electric work machine according to claim 9.

11. The control unit is configured to set the limit threshold value when the first reduction ratio is set by the reduction ratio setting unit to a value different from the limit threshold value when the second reduction ratio is set by the reduction ratio setting unit. The electric work machine according to claim 9 or 10.

12. The control unit is configured such that the limit threshold when the first reduction ratio is set by the reduction ratio setting unit is greater than the limit threshold when the second reduction ratio is set by the reduction ratio setting unit. The electric work machine according to claim 11.

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