JP2020203331A - Power tool - Google Patents

Abstract

To provide a power tool capable of improving workability by suppressing switching of an operation mode when an operator does not intend to switch the operation mode.SOLUTION: A power tool includes: a motor 3; an operation section 7 which is for controlling start and stop of the motor 3; and a control section 10 which detects a load state of the motor 3 and controls the motor 3 on the basis of an operation for the operation section 7. The control section 10 is configured so that an operation mode of the power tool 1 can be switched between a plurality of modes including a first mode and a second mode. When a specific operation is performed for the operation section 7 in a state that the operation mode is in the first mode, and the load state after starting the specific operation satisfies a prescribed condition, the operation mode is switched from the first mode to the second mode. When the prescribed condition is not satisfied even when the specific operation is performed for the operation section 7 in a state that the operation mode is in the first mode, the operation mode is maintained in the first mode.SELECTED DRAWING: Figure 5

Description

The present invention relates to a power tool.

Conventionally, an electric tool configured to start and stop a motor by operating an operation unit provided on a tool body has been widely used. As such a power tool, for example, the impact driver described in Patent Document 1 is known. The impact driver described in Patent Document 1 includes a motor, a trigger switch configured to be retractable, and a control unit that controls the drive of the motor. The control unit is configured to control the start and stop of the motor based on the signal from the trigger switch, and the operation mode of the impact driver can be switched between a plurality of modes based on the signal from the trigger switch. It is configured in.

When switching the operation mode in the above impact driver, the operator performs a specific operation such as pulling in the trigger switch a plurality of times within a short period of time or pressing and holding the trigger switch.

JP-A-2015-47646

In the above impact driver, the operator operates the trigger switch regardless of whether the motor is started or the operation mode is switched. Therefore, even if the operator operates the trigger switch with the intention of starting the motor, if the operation is the same as a specific operation for switching the operation mode, it is against the intention of the operator. There is a problem that the operation mode is switched and the workability is lowered. For example, when the operation mode is switched by pulling the trigger switch a predetermined number of times within a short period of time, the operator intends to repeatedly start and stop the motor within a short period of time. It is conceivable to pull the trigger switch a predetermined number of times. In this case, since the operation and the operation mode switching operation are the same operation, the operation mode may be switched against the intention of the operator, and there is a problem that workability is lowered.

Therefore, an object of the present invention is to provide a power tool capable of improving workability by suppressing the switching of the operation mode when the operator does not intend to switch the operation mode. To do.

In order to solve the above problems, the present invention detects the motor, the operation unit for controlling the start and stop of the motor, the load state of the motor, and controls the motor based on the operation on the operation unit. A power tool including a control unit for operating the power tool, wherein the control unit is configured so that the operation mode of the power tool can be switched between a plurality of modes including a first mode and a second mode. When a specific operation is performed on the operation unit in the state of the first mode and the load state after the start of the specific operation satisfies a predetermined condition, the operation mode is changed from the first mode to the second mode. If the predetermined condition is not satisfied even when the specific operation is performed on the operation unit while the operation mode is the first mode, the operation mode is changed to the first mode. We provide power tools that are characterized by maintaining.

According to the above configuration, when a specific operation is performed on the operation unit, the control unit can switch the operation mode according to the load state of the motor, so that workability can be improved. Become.

In the above configuration, the operation unit is configured to be switchable between an on state and an off state, and the specific operation determines an on operation for switching the operation unit from the on state to the off state within a predetermined period. It is preferable that the operation is performed a number of times.

In the above configuration, the load state after the start of the specific operation is in the first specific period starting from the time when the first on operation, which is one of the on operations performed a predetermined number of times in the specific operation, is performed. The starting point is the time when the first load state, which is the load state in the included first load monitoring period, and the second on operation, which is another one of the on operations performed a predetermined number of times in the specific operation, are performed. It is preferable to include the second load state, which is the load state in the second load monitoring period included in the second specific period.

According to the above configuration, the load state in two periods can be detected as the load information for the motor generated by the on operation, so that the load state of the motor can be reliably detected as compared with the case where only the load state in one period is detected. It becomes possible to grasp.

The first load monitoring period is a period starting from the time when the first on operation is performed, and the second load monitoring period is a time after the time when the second on operation is performed. It is preferable that the period is the starting point.

According to the above configuration, it is possible to detect two types of load states, the load state of the motor immediately after the on operation and the motor load state after a lapse of a predetermined period from the on operation, so that only one of the load states is detected. It is possible to grasp the load state of the motor more reliably than in the case of doing so.

The first load monitoring period is a period starting from a time point after the time when the first on operation is performed, and the second load monitoring period is a time when the second on operation is performed. It is preferable that the period is the starting point.

According to the above configuration, it is possible to detect two types of load states, the load state of the motor immediately after the on operation and the motor load state after a lapse of a predetermined period from the on operation, so that only one of the load states is detected. It is possible to grasp the load state of the motor more reliably than in the case of doing so.

In the above configuration, the load state after the start of the specific operation is in the third specific period starting from the time when the third on operation, which is one of the on operations performed a predetermined number of times in the specific operation, is performed. It is preferable to include a third load state, which is the load state in the included third load monitoring period, and a fourth load state, which is the load state in the fourth load monitoring period included in the third specific period.

According to the above configuration, it is possible to more reliably grasp the load state for the same specific period.

In the above configuration, the third load monitoring period is a period starting from the time when the third on operation is performed, and the fourth load monitoring period is a predetermined period after the end of the third load monitoring period. It is preferable that the period starts from the time point of.

According to the above configuration, it is possible to more reliably grasp the load state for the same specific period.

In the above configuration, the control unit detects the motor current flowing through the motor as the load state, and the predetermined condition is that the motor current in the third load monitoring period indicating the third load state is the first current threshold value. It is preferable that the motor current is satisfied when the motor current does not exceed the second current threshold value which is smaller than the first current threshold value in the fourth load monitoring period indicating the fourth load state.

According to the above configuration, the current threshold value for the period immediately after the motor is started is set to a value larger than the current threshold value for the period after the elapse of a predetermined period from the on operation, and the load after the mode switching operation is started according to the driving condition of the motor. By determining the state, the load state of the motor can be grasped more reliably.

In the above configuration, the load state after the start of the specific operation includes the fifth load state, which is the load state in the fifth load monitoring period starting from the time when the first on operation in the specific operation is performed. The sixth load state, which is the load state in the sixth load monitoring period starting from a predetermined time point after the end of the fifth load monitoring period, and the time point when the second on operation in the specific operation is performed are The seventh load state, which is the load state in the seventh load monitoring period as the starting point, and the eighth load state, which is the load state in the eighth load monitoring period starting from a predetermined time point after the end of the seventh load monitoring period. It is preferable to include a load state.

According to the above configuration, it is possible to detect the load state for four periods including the two load monitoring periods immediately after the two on operations, so that the load state detection period is less than four. It is possible to reliably grasp the load state of the motor.

In the above configuration, the control unit detects the motor current flowing through the motor as the load state, and the predetermined conditions are the motor current and the seventh load in the fifth load monitoring period indicating the fifth load state. The motor current in the 7th load monitoring period indicating the state does not exceed the 3rd current threshold, and the motor current in the 6th load monitoring period indicating the 6th load state and the 8th load state indicating the state are indicated. It is preferable that the motor current is satisfied when the motor current in the eighth load monitoring period does not exceed the fourth current threshold, which is smaller than the third current threshold.

According to the above configuration, the load state for four periods including the two load monitoring periods immediately after the two on operations is detected, and the load state after the start of the mode switching operation is determined according to the motor drive status. By performing the above, the load state of the motor can be grasped more reliably.

In the above configuration, it is preferable that the control unit detects the motor current flowing through the motor as the load state.

In the above configuration, it is preferable that the control unit detects the rotation speed of the motor as the load state.

In the above configuration, in the first mode, when the operation unit is in the on state, the control unit supplies electric power to the motor, and when the operation unit is in the off state, the control unit is said. It is a mode in which the supply of electric power to the motor is stopped, and the second mode is preferably a mode in which the control unit supplies electric power to the motor even when the operation unit is in the off state.

According to the above configuration, the operator can work in a mode in which power is supplied to the motor even when the operation unit is off, if necessary, thus improving operability. be able to.

In the above configuration, there is further an irradiation unit configured to be able to irradiate light, the second mode is a mode in which light is irradiated from the irradiation unit, and in the first mode, the irradiation unit is light. It is preferable that the mode is such that the irradiation of the light is stopped.

In the above configuration, it is preferable that the operation unit is a trigger switch.

According to the present invention, it is possible to provide a power tool capable of improving workability by suppressing the switching of the operation mode when the operator does not intend to switch the operation mode. ..

It is a vertical sectional view which shows the internal structure of the screw tightening machine which concerns on 1st Embodiment of this invention. It is a block diagram which shows the electrical structure of the screw tightening machine which concerns on 1st Embodiment of this invention. It is a figure which shows the time-dependent change of a motor current and a start signal at the time of performing a mode switching operation in a no-load state in the screw tightening machine which concerns on 1st Embodiment of this invention. It is a figure which shows the time-dependent change of a motor current and a start signal at the time of the screw tightening machine which concerns on 1st Embodiment of this invention, when an operator performs a trigger operation similar to a mode switching operation during a tightening operation. .. It is a flowchart explaining the determination of whether or not the operation mode can be switched by the microcomputer, and the process of switching an operation mode in 1st Embodiment of this invention. It is a flowchart explaining the process of the drive control of the motor by the microcomputer by the 1st Embodiment of this invention. It is a figure which shows the correspondence relationship between the condition of the current threshold value which the microcomputer which concerns on 1st modification of 1st Embodiment of this invention refers to in determining the possibility of switching an operation mode, and the possibility of mode switching. It is a figure which shows the correspondence relationship between the condition of the current threshold value which the microcomputer which concerns on the 2nd modification of the 1st Embodiment of this invention is referred to for determining whether or not operation mode switching is possible, and the possibility of mode switching. It is a figure which shows the time-dependent change of the motor rotation speed and the start signal at the time of performing a mode switching operation in a no-load state in the screw tightening machine which concerns on 2nd Embodiment of this invention. In the screw tightening machine according to the second embodiment of the present invention, it is a figure which shows the time-dependent change of a motor rotation speed and a start signal when an operator performs a trigger operation similar to a mode switching operation during a tightening operation. is there.

Hereinafter, the screw tightening machine 1 which is an example of the power tool according to the embodiment of the present invention will be described with reference to FIGS. 1 to 10. The screw tightening machine 1 is an electric power tool for screwing a plate material such as gypsum board to a ceiling or a wall, for example.

In the following description, "front" shown in the figure is defined as forward, "rear" is defined as backward, "up" is defined as upward, and "down" is defined as downward. Further, when the screw tightening machine 1 is viewed from the rear, "right" is defined as the right direction, and "left" is defined as the left direction. Further, regarding the rotatable member, the rotation in the clockwise direction is defined as "forward rotation" and the rotation in the counterclockwise direction is defined as "reversal" in the rear view of the screw tightening machine 1. When the dimensions, numerical values, etc. are referred to in the present specification, not only the dimensions and numerical values that completely match the dimensions and numerical values, but also the dimensions, numerical values, etc. that substantially match (for example, within the range of manufacturing error). Case) shall be included. Similarly, for "identical", "orthogonal", "parallel", "match", "plane", "same diameter", etc., "approximately identical", "approximately orthogonal", "approximately parallel", "approximately coincident", etc. It shall include "approximately flush", "approximately the same diameter", etc.

As shown in FIG. 1, the screw tightening machine 1 is an output shaft to which a housing 2, a motor 3, a clutch portion 5, and a tip tool P can be attached and detached and which can rotate about an axis B extending in the front-rear direction. A unit 6, a trigger switch 7, and a microcomputer 10 are mainly provided.

The housing 2 forms the outer shell of the screw tightening machine 1, and mainly includes a motor housing 21, a handle housing 22, a gear housing 23, and a cover 24.

The motor housing 21 has a cylindrical shape extending in the front-rear direction, and houses the motor 3 and the substrate portion 4. A plurality of intake ports are formed at the rear portion of the motor housing 21 (not shown).

The handle housing 22 is formed in a substantially U-shape in a side view, and has a grip portion 221, a first connection portion 222, and a second connection portion 223.

The grip portion 221 is a portion that can be gripped by an operator, and has a substantially cylindrical shape extending in the vertical direction as shown in FIG. A start signal output unit 22B is housed in the upper part of the grip portion 221 and a trigger switch 7 configured to be manually operated is provided in front of the start signal output unit 22B.

The second connecting portion 223 connects the lower portion of the grip portion 221 and the lower portion of the rear portion of the motor housing 21, and has a substantially cylindrical shape extending in the front-rear direction. The forward / reverse signal output unit 22D is housed in the front portion of the second connection portion 223, and can be manually operated at a position behind the forward / reverse signal output unit 22D on the right side surface of the second connection portion 223. The changeover switch 22C is provided.

The trigger switch 7 is a manually operable switch for controlling the start and stop of the motor 3, and is configured to be switchable between an on state and an off state. In the present embodiment, the state of the trigger switch 7 shown in FIG. 1 is an off state, and a pull operation is performed on the trigger switch 7 from the off state, and the trigger switch 7 is moved backward (not). (Shown) is on. In the following, the operation of switching the trigger switch 7 from the off state to the on state is referred to as "on operation", and the operation of switching from the on state to the off state is referred to as "off operation". The trigger switch 7 is an example of the "operation unit" in the present invention.

The start signal output unit 22B is connected to the microcomputer 10 and is configured to detect a pulling operation on the trigger switch 7 and output a start signal to the microcomputer 10. Specifically, the start signal output unit 22B continues to output the start signal to the microcomputer 10 when the trigger switch 7 is on, and stops the output of the start signal when the trigger switch 7 is off. To do.

The forward / reverse signal output unit 22D is connected to the microcomputer 10, and is configured to detect an operation on the changeover switch 22C and output a forward / reverse signal to the microcomputer 10. Specifically, when the changeover switch 22C is tilted in the clockwise direction of the paper in FIG. 1, the forward / reverse signal output unit 22D transmits a signal for switching the rotation direction of the motor 3 to "forward rotation" to the microcomputer 10. It is configured. Further, when the changeover switch 22C is tilted in the counterclockwise direction of the paper shown in FIG. 1, the forward / reverse signal output unit 22D is configured to transmit a signal for switching the rotation direction of the motor 3 to "reverse" to the microcomputer 10. There is.

Further, the power cord 2A extends from the lower part of the rear portion of the second connection portion 223. The power cord 2A has a connection plug (not shown) that can be connected to the external power supply Q, and is configured to be connectable to the external power supply Q (FIG. 2). In the present embodiment, the external power supply Q is a commercial AC power supply.

The gear housing 23 is formed in a substantially funnel shape that extends in the front-rear direction and tapers from the rear end toward the front. The rear portion of the gear housing 23 is connected to the front end portion of the motor housing 21 via a plurality of screws 2B (the point that a plurality of screws 2B are provided is not shown). The gear housing 23 houses the front portion of the motor 3, the clutch portion 5, and the rear portion of the output shaft portion 6. Further, a plurality of exhaust ports (not shown) are formed at the rear portion of the gear housing 23.

Further, a spring clutch 25 is fixed inside the gear housing 23. The spring clutch 25 has a substantially cylindrical shape extending in the front-rear direction, and the output shaft portion 6 is inserted therethrough. The spring clutch 25 is configured so that the regulation and the permissible of the forward rotation of the output shaft portion 6 can be switched according to the position of the output shaft portion 6 in the front-rear direction.

The cover 24 is made of resin and is formed in a substantially funnel shape that tapers from the rear end toward the front. The cover 24 is fitted into the gear housing 23 so as to cover the outer peripheral surface of the front portion of the gear housing 23.

The motor 3 is a three-phase brushless DC motor configured so that the rotation direction (forward rotation and reverse rotation) can be switched, and is a drive source for the screw tightening machine 1. The motor 3 has a rotating shaft 31, a pinion 32, a rotor 33, a stator 34, a sensor substrate 35, and a fan 36.

The rotation shaft 31 extends in the front-rear direction. The rear end of the rotating shaft 31 is supported by the motor housing 21 via the bearing 31B, and the front end of the rotating shaft 31 is supported by the gear housing 23 via the bearing 31A. In other words, the rotating shaft 31 is rotatably supported by the housing 2 about the axis A, and is rotated by the drive of the motor 3 to generate a rotational force. Here, the axis A is a line that extends in the front-rear direction and passes through the axis of the rotating shaft 31.

The pinion 32 is provided at the front end of the rotating shaft 31 so as to be integrally rotatable with the rotating shaft 31. Further, behind the pinion 32, a fan 36 is provided so as to be rotatable coaxially with the rotating shaft 31. In the present embodiment, when the fan 36 rotates, outside air is taken into the housing 2 from an intake port (not shown) formed in the motor housing 21, and the gear housing 23 cools each component of the motor 3. It is configured to exhaust air from an exhaust port (not shown) formed in the housing.

The rotor 33 has a permanent magnet 33A, and is coaxially fixed to the rotating shaft 31 so as to rotate coaxially with the rotating shaft 31. Further, a sensor magnet (not shown) is provided at the rear end of the rotor 33 so as to rotate integrally with the rotor 33.

The stator 34 has a substantially cylindrical shape extending in the front-rear direction, and has star-shaped connected stator coils U, V, and W (FIG. 2). Each of the upper portion and the lower portion of the outer peripheral portion of the stator 34 is fixed to the motor housing 21 by bolts (not shown).

The sensor substrate 35 is a substrate having an annular shape when viewed from the front, and is provided behind the stator 34 of the motor 3. Three Hall elements 35A, 35B, and 35C for detecting the rotational position of the rotor 33 are mounted on the front surface of the sensor substrate 35.

The three Hall elements 35A, 35B, and 35C are provided on the front surface of the sensor substrate 35, and are arranged side by side at intervals of approximately 60 ° in the circumferential direction of the rotating shaft 31. Each of the three Hall elements 35A, 35B, and 35C is connected to the microcomputer 10, and outputs a signal for detecting the rotation position of the sensor magnet to the microcomputer 10.

As shown in FIG. 1, the substrate portion 4 is provided at the rear portion of the motor 3 and has a substrate case 40. The substrate case 40 has a substantially rectangular parallelepiped shape with the front open, and is arranged in the motor housing 21 so that the shortest side thereof is parallel to the front-rear direction. A circuit board (not shown) is housed in the board case 40. The circuit board is arranged in the board case 40 so that both sides thereof are orthogonal to the front-rear direction, and a microcomputer 10 or the like for controlling the motor 3 is mounted.

As shown in FIG. 1, the clutch portion 5 has a clutch drum 51 and a multi-plate friction clutch 52. The clutch drum 51 has a substantially cylindrical shape extending in the front-rear direction and having an opening formed in the front portion, and is rotatably supported about the axis B via a bearing 5A and a bearing metal 5B. Here, the axis B is a line extending in the front-rear direction and passing through the axis of the output shaft portion 6. An engaging portion 51A is provided on the inner peripheral surface of the front portion of the clutch drum 51, a gear portion 51B is provided on the outer peripheral surface of the substantially central portion, and a one-way clutch 51C is provided on the inner peripheral surface of the substantially central portion. , A spring 51D is housed in the rear part.

The engaging portion 51A extends in the front-rear direction on the inner peripheral surface of the front portion of the clutch drum 51. Although not shown in detail in the figure, the engaging portion 51A has a groove that is recessed outward in the radial direction of the clutch drum 51 from the inner peripheral surface of the clutch drum 51 and extends in the front-rear direction in the entire circumferential direction of the clutch drum 51. It is formed at predetermined intervals.

The gear portion 51B has a plurality of gear teeth and meshes with the pinion 32 of the motor 3. As a result, the rotational force from the motor 3 is transmitted to the clutch drum 51 to drive the clutch drum 51 in rotation. The one-way clutch 51C has an outer ring portion fixed (press-fitted) to the inner peripheral surface of the clutch drum 51, and an inner ring portion in which normal rotation is restricted with respect to the outer ring portion and reverse rotation is permitted.

The spring 51D is arranged inside the rear portion of the clutch drum 51 so as to be expandable and contractible in the front-rear direction. The rear end of the spring 51D is in contact with the wall forming the rear end of the clutch drum 51, and the front end is in contact with the rear end of the output shaft 6 to urge the output shaft 6 forward.

The multi-plate friction clutch 52 is housed in a clutch drum 51, and is configured by alternately laminating an outer plate formed in a substantially disk shape and an inner plate formed in a substantially disk shape in the front-rear direction. Although not shown in detail in the figure, each of the plurality of outer plates has a substantially annular shape in the front view, and an engaged portion capable of engaging with the engaging portion 51A of the clutch drum 51 is formed on the outer peripheral portion of the outer plate. It is provided at predetermined intervals in the circumferential direction. Further, each of the plurality of inner plates has a substantially annular shape in the front view, and an engaged portion that projects inward in the radial direction of the inner plate is provided on the inner peripheral portion thereof. The engaged portions of the inner plate are provided at predetermined intervals in the circumferential direction of the inner plate. Further, since the outer plate and the inner plate are laminated in the front-rear direction, a through hole 52a extending in the front-rear direction is formed at a substantially central portion in the radial direction of the multi-plate friction clutch 52.

The multi-plate friction clutch 52 is configured to be able to transmit the rotational force of the clutch drum 51 that rotates by receiving the rotational force of the motor 3 to the output shaft portion 6 by being pressed in the front-rear direction. Specifically, the multi-plate friction clutch 52 is provided between the clutch drum 51 and the output shaft portion 6 in the transmission path of the driving force (rotational force) of the motor 3, and the output shaft portion 6 moves rearward. In addition to being pressed, the driving force of the motor 3 is transmitted to the output shaft portion 6 in response to the pressing force.

As shown in FIG. 1, the rear portion of the output shaft portion 6 is housed in the gear housing 23, and the front portion thereof extends forward from the front portion of the gear housing 23. The output shaft portion 6 has a spline shaft 61 and a bit mounting portion 62.

The bit mounting portion 62 has a substantially cylindrical shape extending in the front-rear direction, and is supported by a spring clutch 25 so as to be rotatable around the axis B as a rotation center and movable in the front-rear direction. The bit mounting portion 62 is formed with a through hole 62a extending in the front-rear direction.

The spline shaft 61 has a substantially cylindrical shape extending in the front-rear direction, and is inserted into a through hole 52a of the multi-plate friction clutch 52. The front end of the spline shaft 61 is press-fitted into the through hole 62a of the bit mounting portion 62, and the rear end of the spline shaft 61 is supported by a one-way clutch 51C provided on the clutch drum 51 so as to be rotatable and movable in the front-rear direction. Has been done.

Further, an engaging portion 61A extending in the front-rear direction is provided at a substantially central portion of the spline shaft 61 in the front-rear direction. The engaging portion 61A is formed with projecting portions extending outward in the radial direction of the spline shaft 61 from the outer peripheral surface of the spline shaft 61 and extending in the front-rear direction at predetermined intervals over the entire circumferential direction of the spline shaft 61. The engaging portion 61A is engaged with an engaging portion (not shown) provided on the plurality of inner plates, and when the plurality of inner plates rotate, the engaging portion 61A and the plurality of inner plates, the spline shaft 61, and the bit mounting portion 62 Rotates integrally.

Next, the electrical configuration of the screw tightening machine 1 will be described. The screw tightening machine 1 has a power supply circuit 9 and a microcomputer 10 as shown in FIG. The power supply circuit 9 and the microcomputer 10 are mounted on a circuit board housed in a board case 40.

The power supply circuit 9 is configured to be able to supply the power of the external power supply Q to the motor 3, and includes a noise filter circuit 42, a rectifier circuit 43, a plus line 44, a minus line 46, a smoothing circuit 47, and a shunt. It has a resistor 45, an inverter circuit 48, and a constant voltage power supply circuit 49.

The noise filter circuit 42 is a circuit for reducing noise, and has a first terminal 42B, a second terminal 42C, a choke coil 42D, and a capacitor 42E. The first terminal 42B and the second terminal 42C are terminals to which the voltage of the external power supply Q is applied while the power cord 2A is connected to the external power supply Q.

The choke coil 42D and the capacitor 42E are filter elements for reducing noise propagating from the external power supply Q to the power supply circuit 9. The choke coil 42D is connected in series between the rectifier circuit 43 and the external power supply Q, and the capacitor 42E is connected in parallel with the external power supply Q.

The rectifier circuit 43 is a diode bridge circuit having four diodes 43A (four rectifier elements), and rectifies the AC voltage output from the external power supply Q via the noise filter circuit 42 and outputs the AC voltage to the smoothing circuit 47. In other words, the rectifier circuit 43 converts the AC voltage of the external power supply Q into a DC voltage and outputs it to the smoothing circuit 47.

The plus line 44 connects the rectifier circuit 43 and the inverter circuit 48. Further, the minus line 46 is connected to a GND (not shown), and also connects the rectifier circuit 43 and the inverter circuit 48.

The smoothing circuit 47 is connected between the rectifier circuit 43 and the inverter circuit 48, smoothes the DC voltage output from the rectifier circuit 43, and outputs the DC voltage to the inverter circuit 48. The smoothing circuit 47 has a first capacitor 47A, a second capacitor 47B, and a resistor 47C.

The first capacitor 47A is a polar electrolytic capacitor and is connected between the plus line 44 and the minus line 46.

The second capacitor 47B is a non-polar film capacitor and is connected between the plus line 44 and the minus line 46.

The resistor 47C is a resistor for discharging, is connected between the plus line 44 and the minus line 46, and is connected in parallel with the second capacitor 47B.

The shunt resistor 45 is provided between the smoothing circuit 47 and the inverter circuit 48 on the minus line 46. The shunt resistor 45 is a resistor used to detect the current flowing through the motor 3, and both ends of the shunt resistor 45 are connected to the microcomputer 10.

The inverter circuit 48 has six switching elements Q1 to Q6 connected in a three-phase bridge type. In the present embodiment, the switching elements Q1 to Q6 are MOSFETs (Metal Oxide Semiconductor Field Effect Transistor), but are not limited to these, and may be switching elements such as an IGBT (Insulated Gate Bipolar Transistor).

Each gate of the switching elements Q1 to Q6 is connected to the microcomputer 10, and performs a switching operation based on a control signal input from the microcomputer 10. Further, each drain or each source of the switching elements Q1 to Q6 is connected to the stator coils U, V, and W.

As shown in FIG. 2, the constant voltage power supply circuit 49 is connected between the plus line 44 and the minus line 46. The constant voltage power supply circuit 49 has a diode 49A, a capacitor 49B, an IPD circuit 49C, a capacitor 49D, and a regulator 49E, and converts the DC voltage output from the rectifier circuit 43 to generate a stabilized reference voltage. Then, it is supplied to the microcomputer 10 and the like.

The microcomputer 10 has a calculation unit, a ROM, a RAM, and the like (not shown), and is configured to control the inverter circuit 48 to drive the motor 3. The microcomputer 10 detects the rotational position of the rotor 33 by detecting the rotational position of the sensor magnet based on the signals output from each of the three Hall elements 35A, 35B, and 35C, and the switching element is based on the detection result. A control signal for switching on / off of each of Q1 to Q6 is formed. The microcomputer 10 outputs the control signal to the switching elements Q1 to Q6, sequentially switches the energized coil among the stator coils U, V, and W, and drives the rotor 33 to rotate in the rotation direction set by the changeover switch 22C. Let me.

Further, the microcomputer 10 is configured to be able to detect load information indicating the load of the motor 3. In the present embodiment, the microcomputer 10 detects the motor current flowing through the motor 3 as load information, monitors the load of the motor 3 based on the motor current, and controls the motor 3 based on the operation of the trigger switch 7. It is configured in. The microcomputer 10 detects the motor current by taking in the voltage drop value of the shunt resistor 45 and calculating the value of the current flowing through the shunt resistor 45 based on the voltage drop value. The microcomputer 10 has a timekeeping function and can store information about the timed period.

The microcomputer 10 is configured so that the operation mode of the screw tightening machine 1 can be switched between a plurality of modes. In the present embodiment, the screw tightening machine 1 has a "normal mode" and an "on-lock mode" as operation modes. In the normal mode, when the trigger switch 7 is in the on state, power is supplied to the motor 3 to drive the motor 3, and when the trigger switch 7 is in the off state, the power supply to the motor 3 is stopped to stop the motor 3. This is the operation mode. On the other hand, the on-lock mode is an operation mode in which the microcomputer 10 supplies electric power to the motor 3 to drive the motor 3 even when the trigger switch 7 is off. Switching the operation mode from the normal mode to the on-lock mode by the microcomputer 10 is performed when a specific operation is performed on the trigger switch 7 and the load state of the motor after the start of the specific operation satisfies a predetermined condition. Only done in. The details of mode switching will be described later. The microcomputer 10 is an example of the "control unit" in the present invention.

Next, with reference to FIG. 1, the screw tightening work and the operation of the screw tightening machine 1 during the tightening work using the screw tightening machine 1 to a work material (plate material or the like) (not shown) will be described. In the following description, unless otherwise specified, it is assumed that the direction in which the tip tool P is pressed against the screw (that is, the direction in which the screw tightening machine 1 is pushed toward the screw) and the forward direction are the same.

When tightening the screw, the operator first attaches the tip tool P to the through hole 62a of the bit mounting portion 62 of the output shaft portion 6, tilts the changeover switch 22C counterclockwise on the paper surface, and triggers the switch 7. Perform a pull operation on. Then, electric power is supplied from the external power source Q to the motor 3 via the power cord 2A, and the motor 3 starts driving. When the motor 3 starts driving, the rotating shaft 31 and the pinion 32 reverse around the axis A as the center of rotation. As the pinion 32 is reversed, the clutch drum 51 rotates forward about the axis B via the gear portion 51B that meshes with the pinion 32. Along with the normal rotation of the clutch drum 51, the plurality of outer plates engaged (engaged) with the engaging portion 51A of the clutch drum 51 rotate forward with the axis B as the rotation axis.

In this state, the operator engages the tip of the tip tool P with a groove (for example, a cross groove) formed in the screw head of the screw. After that, the operator pushes the main body of the screw tightening machine 1 toward the screw and pushes the tip tool P against the screw. At this time, the output shaft portion 6 (spline shaft 61 and bit mounting portion 62) moves rearward against the urging force of the spring 51D. When the output shaft portion 6 moves rearward, the rear end of the bit mounting portion 62 and the inner plate located at the foremost end of the multi-plate friction clutch 52 come into contact with each other. At this time, the adjacent outer plates and inner plates of the multi-plate friction clutch 52 come into contact with each other.

In this state, when the output shaft portion 6 moves further rearward as the main body of the screw tightening machine 1 is further pushed into the screw, the surface pressure on the contact surface between the outer plate and the inner plate adjacent to each other in the front-rear direction increases. To rise. At this time, due to the frictional force generated between the outer plate and the inner plate due to the normal rotation of the outer plate, the rotational force of the motor 3 transmitted to the outer plate is transmitted to the inner plate, and the output rotates integrally with the inner plate. The shaft portion 6 rotates. Then, the rotational force from the motor 3 is transmitted to the tip tool P via the bit mounting portion 62 of the output shaft portion 6, and the screw can be tightened to the work piece (not shown).

Further, when the screw tightening work is completed and the operator separates the tip tool P from the screw head of the screw, the output shaft portion 6 moves forward by the urging force of the spring 51D. As a result, the pressure on the multi-plate friction clutch 52 in the front-rear direction is eliminated, and the surface pressure on the contact surfaces of the adjacent outer plates and inner plates in the front-rear direction is reduced, so that the pressure is generated between the adjacent outer plates and the inner plates. Friction is reduced.

On the other hand, when loosening the screw, the changeover switch 22C is tilted clockwise on the paper to pull the trigger switch 7. At this time, if the operator can sufficiently press the tip tool P against the screw, the output shaft portion 6 moves backward by pressing the tip tool P against the screw. Then, as the rear end portion of the bit mounting portion 62 of the output shaft portion 6 presses the multi-plate friction clutch 52 rearward, the surface pressure between the outer plate and the inner plate adjacent to each other in the front-rear direction increases. Friction occurs between the adjacent outer plate and inner plate as the outer plate is inverted. Due to this friction, the inner plate is inverted, and the output shaft portion 6 is also inverted due to the engagement between the engaged portion (not shown) of the inner plate and the engaging portion 61A of the spline shaft 61. Therefore, the rotational force from the motor 3 is transmitted to the tip tool P via the bit mounting portion 62 of the output shaft portion 6, and the screw can be loosened.

When loosening a screw, the screw head of the screw does not protrude from the work material (for example, when the screw is buried in the work material), and the operator sufficiently attaches the tip tool P to the screw. If it cannot be pressed, the bit mounting portion 62 cannot be sufficiently moved rearward, and sufficient friction does not occur between the outer plate and the inner plate. In this case, the rotational force of the motor 3 cannot be transmitted from the clutch drum 51 to the output shaft portion 6 via the outer plate and the inner plate, but the clutch drum 51 is inverted, so that the clutch drum 51 is inverted, so that the clutch drum 51 is reversed via the one-way clutch 51C. The rotational force is transmitted from the clutch drum 51 to the spline shaft 61, and the screws can be loosened.

Next, switching of the operation mode will be described. The above-mentioned specific operation for switching the operation mode from the normal mode to the on-lock mode is an operation in which the trigger switch 7 is turned on a predetermined number of times within a predetermined period TS. In the present embodiment, the predetermined period TS is 400 ms, and the predetermined number of times is 2, but the present invention is not limited to this, and can be appropriately set. In the following description, a specific operation for switching the operation mode from the normal mode to the on-lock mode is referred to as a "mode switching operation".

However, even when the operator performs normal work (work not intended to switch the operation mode) using the screw tightening machine 1, the trigger switch 7 may perform the same operation as the mode switching operation. .. For example, when an operator tightens a screw on a plate material, in order to increase the certainty of tightening the screw, a pull on the trigger switch 7 is performed with the tip of the tip tool P engaged in a groove formed in the screw head. The operation may be repeated within a short period of time (hereinafter referred to as “tightening”). The operation on the trigger switch 7 when the operator performs the tightening and the mode switching operation (on operation twice within 400 ms) in the present embodiment both pull the trigger switch 7 a plurality of times within a short period of time. Since it involves an operation, the operation mode may be unintentionally switched and the workability may be deteriorated even when the operator is performing the tightening work.

When the operator is performing the screw tightening work using the screw tightening machine 1, the tip tool P is in a state of being pressed against the screw head, so that the tip tool P is not in contact with the screw head. The load on the motor 3 is larger than that in the case where the motor is driven in the (hereinafter, no load state). Therefore, in the screw tightening machine 1 of the present embodiment, when the operator performs the mode switching operation, the load state of the motor 3 is monitored, and when the load is larger than the predetermined value, the operation mode is switched. It is configured to switch the operation mode to the on-lock mode when the load is smaller than the predetermined value without performing the operation.

In the state where the operation mode is the normal mode, the microcomputer 10 performs a mode switching operation on the trigger switch 7, and satisfies a predetermined condition regarding a specific load state which is a load state of the motor 3 after the mode switching operation is started. In this case, the operation mode is configured to switch from the normal mode to the on-lock mode. Further, even if the specific operation is performed on the trigger switch 7 while the operation mode is the normal mode, the microcomputer 10 sets the operation mode to the normal mode when the predetermined condition is not satisfied. It is configured to maintain. Hereinafter, regarding the specific load state that must be satisfied in order for the microcomputer 10 to switch the operation mode to the on-lock mode when the operation mode is the normal mode and the mode switching operation is performed on the trigger switch 7. The predetermined condition of is called "mode switching permission condition".

In the present embodiment, the specific load state includes the load state for four periods. Specifically, the period T1 starting from the time when the first on operation (first on operation) of the two on operations included in the mode switching operation is performed, and the end point of the period T1 as the starting point. The period from the time when the first on operation is performed until the period T2 elapses, and the time when the second on operation (second on operation) of the two on operations included in the mode switching operation is performed. The load state of the motor 3 is included in the period T3 starting from the period T3 and the period from the time when the second on operation is performed to the elapse of the period T4 starting from the end point of the period T3. In the present embodiment, the period T1 and the period T3 are 160 ms, and the period T2 and the period T4 are 210 ms. In the present embodiment, the load information indicating the load state of the motor 3 detected by the microcomputer 10 is the current flowing through the motor 3 (hereinafter referred to as the motor current).

In the present embodiment, the mode switching operation is performed on the trigger switch 7 in the state where the operation mode is the normal mode, and the condition of the current threshold value provided corresponding to each of the four periods is satisfied. In this case, the microcomputer 10 is configured to switch the operation mode from the normal mode to the on-lock mode.

In the present embodiment, when the microcomputer 10 determines whether to switch the operation mode from the normal mode to the on-lock mode, the conditions of the current threshold values provided corresponding to each of the four periods are satisfied. Judge according to whether or not there is. In the microcomputer 10, when the mode switching operation is performed, the motor current in the four periods (load monitoring period) for monitoring the load of the motor 3 is equal to or higher than the current threshold value provided corresponding to each of the four periods. It is configured to determine if.

For example, if each of the motor currents in the four load monitoring periods is less than the corresponding threshold, it is highly likely that the operator is performing a mode switching operation to switch the operation mode to the on-lock mode in the no-load state. Conceivable. On the other hand, when even one of the motor currents in the four load monitoring periods is equal to or higher than the corresponding threshold value, the operator switches the trigger switch to perform the tightening work with the tip tool P in contact with the screw head. It is highly probable that the on state and the off state of 7 are repeated within a short period of time. In the latter case of the tightening work, it is considered that a larger load is generated on the motor 3 as compared with the former case of no load. Therefore, in the present embodiment, the microcomputer 10 switches the operation mode to the on-lock mode when the motor current is less than the threshold value corresponding to each of the four periods in all the four load monitoring periods, and the motor current. Is configured to maintain the normal mode without switching the operation mode when there is at least one load monitoring period in which is equal to or greater than the corresponding threshold value.

FIG. 3 shows a motor in a no-load state (a state in which the tip tool P of the screw tightening machine 1 is not in contact with the screw head) and the operator performs a mode switching operation to switch the operation mode to the on-lock mode. The time course of the current (I) (vertical axis) and the time course of the start signal (vertical axis) are shown (horizontal axis: time t). In FIG. 3, the trigger switch 7 is turned on a total of two times at the time points t11 and t15, and the trigger switch 7 is turned off a total of two times at the time points t13 and t18. Further, the second on operation (t15) is performed from the time t11 when the first on operation is performed until the elapse of the predetermined period TS.

The microcomputer 10 determines whether or not each of the motor currents in the four load monitoring periods shown in FIG. 3 is less than the corresponding threshold value. The four load monitoring periods are the first period (t11 to t12) from the time when the first on operation is performed (t11) to the time when the period T1 elapses (t12), starting from t12 and performing the first on operation. The second period (t12 to t14) from the time when the period T2 elapses (t14), and the third period (t17) from the time when the second on operation is performed (t15) to the time when the period T3 elapses (t17). It is the fourth period (t17 to t19) from the time when the second on operation is performed to the time when the period T4 elapses (t19) starting from t15 to t17) and t17.

As shown in FIG. 3, the current threshold of the first period (t11 to t12) is I1, the current threshold of the second period (t12 to t14) is I2, and the current threshold of the third period (t15 to t17) is I2. I3, the current threshold of the fourth period is I4. The first period and the third period are periods immediately after the on operation is performed, and are periods for monitoring the starting current flowing through the motor 3. The second period and the fourth period are periods starting from a time point when a predetermined period has elapsed from the on operation (motor start), and are periods for monitoring the motor current flowing in a steady state. Since the starting current that flows immediately after the on operation (immediately after starting the motor) is usually larger than the motor current that flows in the steady state, the current thresholds I1 and I3 in the first and third periods are the currents in the second and fourth periods. Values larger than the thresholds I2 and I4 are set. In this embodiment, the current thresholds I1 and I3 are 40A, and the current thresholds I2 and I4 are 20A.

As shown in FIG. 3, the motor current is less than the current threshold value of each period in any of the first to fourth periods. In this case, since the on operation is performed twice within the predetermined period TS (time points t11 and t15) and the motor current is less than the corresponding current threshold value in all four load monitoring periods, the microcomputer 10 switches the mode. It is determined that the permission condition is satisfied, and the operation mode of the screw tightening machine 1 is switched to the on-lock mode.

On the other hand, FIG. 4 shows a state in which the tip tool P of the screw tightening machine 1 is in contact with the screw head, and the trigger switch 7 is turned on and off for a short period of time so that the operator can perform additional tightening work. The change in the motor current (I) (vertical axis) and the change over time (vertical axis) of the start signal when repeated in the above direction are shown (horizontal axis: time t). As shown in FIG. 4, a total of two on operations are performed on the trigger switch 7 at time points t21 and t25, and a total of two off operations are performed on the trigger switch 7 at time points t23 and t28. It has been. Further, the second on operation (t25) is performed from the time t21 when the first on operation is performed until the elapse of the predetermined period TS.

In FIG. 4, the four load monitoring periods in which the microcomputer 10 determines the motor current are the fifth period (t21 to t22) from the time when the first on operation is performed (t21) to the time when the period T1 elapses (t22). ), The sixth period (t22 to t24) from the time when the first on operation is performed to the time when the period T2 elapses (t24), and the period from the time when the second on operation is performed (t25). The seventh period (t25 to t27) up to the time when T3 has passed (t27), and the eighth period (t27 to t27) from the time when the second on operation is performed to the time when the period T4 has passed (t29) starting from t27. t29).

As shown in FIG. 4, the motor currents in the 5th, 7th, and 8th periods exceed the current thresholds of the respective periods. In this case, although the on-operation is performed twice within the period TS, the microcomputer 10 uses the screw tightening machine 1 because the condition for the current threshold value provided corresponding to each load monitoring period is not satisfied. Do not switch the operation mode of to the on-lock mode, and maintain the normal mode.

Next, the determination of whether or not the operation mode can be switched by the microcomputer 10 and the process of switching the operation mode will be described in detail with reference to the flowchart shown in FIG.

When the operator connects the connection plug of the power cord 2A to the external power supply Q, power is supplied to the microcomputer 10, and the process shown in the flowchart of FIG. 5 is started with this as an opportunity.

In step S101, the microcomputer 10 sets the operation mode of the screw tightening machine 1 to the normal mode, which is the initial mode. After that, the microcomputer 10 determines whether or not the ON state of the trigger switch 7 is detected, that is, whether or not the start signal is output from the start signal output unit 22B (step S103).

When it is determined in step S103 that the ON state of the trigger switch 7 has not been detected (step S103: NO), the microcomputer 10 again determines in step S103. That is, the microcomputer 10 repeats the determination in step S103 until it detects the ON state of the trigger switch 7.

When it is determined in step S103 that the on state of the trigger switch 7 has been detected (step S103: YES), the microcomputer 10 has detected the on state of the trigger switch 7 in step S103 (the first on operation is detected). It is determined whether or not the elapsed period TA from the time when it is determined to be) is the period T1 or more (step S105). When the microcomputer 10 determines that the elapsed period TA is less than the period T1 (step S105: NO), the microcomputer 10 determines whether the motor current is equal to or greater than the current threshold value I1 (step S107). When the motor current is equal to or higher than the current threshold value I1 (step S107: YES), the microcomputer 10 returns to step S103 and makes a determination.

If the motor current is less than the current threshold value I1 in step S107 (step S107: NO), the microcomputer 10 again determines S105. As long as the elapsed period TA is less than the period T1, the microcomputer 10 determines whether the motor current is equal to or greater than the current threshold value I1.

In step S105, when it is determined that the elapsed period TA is the period T1 or more (step S105: YES), the microcomputer 10 determines whether the elapsed period TA is the period T2 or more (step S109). When the microcomputer 10 determines that the elapsed period TA is less than the period T2 (step S109: NO), the microcomputer 10 determines whether the motor current is equal to or greater than the current threshold value I2 (step S111). When the motor current is equal to or higher than the current threshold value I2 (step S111: YES), the microcomputer 10 returns to step S103 and makes a determination.

When it is determined in step S111 that the motor current is less than the current threshold value I2 (step S111: NO), the microcomputer 10 again determines S109. That is, the microcomputer 10 determines whether or not the motor current is the current threshold value I2 or more in the period when the elapsed period TA is the period T1 or more and the period T2 or less.

When it is determined in step S109 that the elapsed period TA is the period T2 or more (step S109: YES), the microcomputer 10 determines whether the elapsed period TA is the period TS or more (step S113). When the microcomputer 10 determines that the elapsed period TA is equal to or longer than the period TS (step S113: YES), the microcomputer 10 returns to step S103 and makes a determination. When the elapsed period TA is equal to or longer than the predetermined period TS, it means that the second on operation was not detected within the period from the time when the first on operation was performed until the period TS elapsed, and the mode switching operation was not performed. ing.

When it is determined in step S113 that the elapsed period TA is less than the period TS (step S113: NO), that is, when the elapsed period from the time when the first on operation is performed is less than the period TS, the microcomputer 10 determines. It is determined whether or not the off state of the trigger switch 7 is detected (step S115). Here, the determination in step S115 indicates whether or not the trigger switch 7 is turned off during the detection determination of the on state of the trigger switch 7 in step S103 and step S119 described later. In other words, if the affirmative judgment is made in all of steps S103, S115, and S119, the off operation is not performed after the first on operation and the on state of the trigger switch 7 is not maintained, but two on operations are performed. Indicates that it is being done.

If the microcomputer 10 has not detected the off state of the trigger switch 7 in step S115 (step S115: NO), the microcomputer 10 determines step S113 again. On the other hand, when the microcomputer 10 determines that the off state of the trigger switch 7 is detected (step S115: YES), the microcomputer 10 determines whether the elapsed period TA is the period TS or more (step S117). When it is determined that the elapsed period TA is equal to or longer than the period TS (step S117: YES), the process returns to step S103 to make a determination.

When it is determined in step S117 that the elapsed period TA is less than the period TS (step S117: NO), the microcomputer 10 determines whether or not the ON state of the trigger switch 7 is detected (step S119). If the microcomputer 10 has not detected the ON state of the trigger switch 7 (step S119: NO), the microcomputer 10 determines step S117 again. On the other hand, when the microcomputer 10 determines that the trigger switch 7 is in the ON state (step S119: YES), the microcomputer 10 determines in step S121.

Whether the period TB from the time when the microcomputer 10 determines in step S121 that the on state of the trigger switch 7 is detected in step S103 to the time when it is determined that the on state of the trigger switch 7 is detected in step S119 is the period TS or more. Judge whether or not. That is, in step S121, the microcomputer 10 determines whether the period TB is equal to or longer than the period TS. When it is determined that the period TB is equal to or longer than the period TS (step S121: YES), the microcomputer 10 determines that the mode switching operation (twice on operation within the predetermined period TS) has not been performed, and returns to step S103. Make a decision.

When the microcomputer 10 determines in step S121 that the elapsed period TB is less than the period TS (step S121: NO), a mode switching operation (two on operations within a predetermined period (period TS)) has been detected. Is shown. In this case, the microcomputer 10 determines whether or not the elapsed period TC from the time when it is determined that the ON state of the trigger switch 7 is detected in step S119 is the period T3 or more (step S123). When the microcomputer 10 determines that the elapsed period TC is less than the period T3 (step S123: NO), that is, when the microcomputer 10 determines that the elapsed period from the time when the second on operation is performed is less than the period T3, the motor current. Determines if is greater than or equal to the predetermined current threshold I3 (step S125). When the motor current is equal to or higher than the current threshold value I3 (step S125: YES), the microcomputer 10 returns to step S103 and makes a determination.

If the motor current is less than the current threshold value I3 in step S125 (step S125: NO), the microcomputer 10 makes the determination in step S123 again. In the microcomputer 10, as long as the elapsed period TC is less than the period T3 (step S123: NO), that is, during the period from the time when the second on operation is performed until the period T3 elapses, whether or not the motor current is the current threshold value I3 or more Make a decision.

When it is determined in step S123 that the elapsed period TC is the period T3 or more (step S123: YES), the microcomputer 10 determines whether the elapsed period TC is the predetermined period (T4) or more (step S127). When the microcomputer 10 determines that the elapsed period TC is less than the period T4 (step S127: NO), that is, when the microcomputer 10 determines that the elapsed period from the time when the second on operation is performed is less than the period T4, the motor current is predetermined. It is determined whether or not the current threshold value is I4 or more (step S129). When the motor current is equal to or higher than the current threshold value I4 (step S129: YES), the microcomputer 10 returns to step S103 and makes a determination.

When the motor current is less than the current threshold value I4 in step S129 (step S129: NO), the microcomputer 10 again determines S127. As long as the elapsed period TC from the time when the microcomputer 10 determines that the ON state of the trigger switch 7 is detected in step S119 is the period T3 or more and less than the period T4, that is, the elapsed time from the time when the second ON operation is performed. As long as the period TC is the period T3 or more and less than the period T4, it is determined whether or not the motor current is the current threshold value I4 or more.

When the microcomputer 10 determines in step S127 that the elapsed period TC is the period T4 or more (step S127: YES), it means that the mode switching operation is performed and the mode switching permission condition is satisfied. In this case, the microcomputer 10 switches the operation mode of the screw tightening machine 1 from the normal mode to the on-lock mode (step S131).

After that, the microcomputer 10 determines whether or not the off state of the trigger switch 7 is detected (step S133), and if the off state of the trigger switch 7 is not detected (step S133: NO), the determination of step S133 is made again. Do. The microcomputer 10 repeats the determination in step S133 until it detects the ON state of the trigger switch 7 in step S133.

When it is determined in step S133 that the off state of the trigger switch 7 is detected (step S133: YES), it is determined whether or not the on state of the trigger switch 7 is detected (step S135), and the on state of the trigger switch 7 is detected. If not (step S135: NO), the determination in step S135 is performed again. The microcomputer 10 repeats the determination in step S135 until it detects the ON state of the trigger switch 7 in step S135.

When the microcomputer 10 determines in step S135 that the trigger switch 7 is in the ON state (step S135: YES), the microcomputer 10 switches the operation mode of the screw tightening machine 1 from the on-lock mode to the normal mode (step S137). After that, the microcomputer 10 determines whether or not the off state of the trigger switch 7 is detected (step S139).

When it is determined in step S139 that the off state of the trigger switch 7 has not been detected (step S139: NO), the microcomputer 10 again determines in step S139. That is, the microcomputer 10 repeats the determination in step S139 until the off state of the trigger switch 7 is detected in step S139. On the other hand, when the off state of the trigger switch 7 is detected in step S139 (step S139: YES), the microcomputer 10 returns to step S103 and makes a determination.

Next, the process of driving control of the motor 3 by the microcomputer 10 will be described in detail with reference to the flowchart shown in FIG.

The microcomputer 10 determines in step S201 whether or not the trigger switch 7 is in the ON state. When it is determined that the trigger switch 7 is not in the ON state (step S201: NO), the determination in step S201 is performed again. That is, the microcomputer 10 repeats the determination in step S201 until it detects the ON state of the trigger switch 7.

When detecting the ON state of the trigger switch 7 in step S201 (step S201: YES), the microcomputer 10 starts the motor 3 (step S203). Specifically, the microcomputer 10 outputs a control signal to the switching elements Q1 to Q6, and controls the motor 3 so as to supply electric power. After that, the microcomputer 10 detects whether or not the trigger switch 7 is in the off state in step S205. When it is determined in step 205 that the trigger switch 7 is not in the off state (step S205: NO), the determination in step S205 is performed again. The microcomputer 10 repeats the determination in step S205 until it detects the off state of the trigger switch 7.

When it is determined in step 205 that the trigger switch 7 is in the off state (step S205: YES), the microcomputer 10 has a period (TD) elapsed from the time when the on state of the trigger switch 7 is detected in step S201 is a period T4 or more. Whether or not it is determined (step S207). When it is determined that the elapsed period TD is less than the period T4 (step S207: NO), the microcomputer 10 again determines in step S207. That is, the microcomputer 10 repeats the determination in step S207 from the time when the ON state of the trigger switch 7 is detected in step S201 until the period T4 elapses.

Here, the determination in step S207 corresponds to the determination in step S127 in FIG. That is, when the ON state of the trigger switch 7 in step S201 corresponds to the second ON operation (step S119 in FIG. 5) of the mode switching operations, the period T4 from the time when the ON operation is performed. Until that time elapses, the operation mode does not switch to the on-lock mode (that is, whether or not switching is possible is not determined). Therefore, by repeating the determination in step S207, the microcomputer 10 waits until it is determined whether or not the operation mode can be switched, and suppresses the determination in step S209 before the operation mode is switched. As a result, even though the operation mode is the on-lock mode, the motor drive control corresponding to the on-lock mode (step S213 described later) is not executed, and the motor drive control corresponding to the normal mode (step S211 described later) is not executed. Is prevented from being done.

When it is determined in step S207 that the elapsed period TD is the period T4 or more (step S207: YES), the microcomputer 10 determines whether the operation mode is the on-lock mode (step S209). When it is determined that the operation mode is not the on-lock mode (step S209: NO), the microcomputer 10 stops driving the motor 3. That is, when it is determined in step S205 that the off state of the trigger switch 7 is detected and it is determined in step S209 that the operation mode is the on-lock release mode, the drive of the motor 3 is stopped in step S211. Specifically, the microcomputer 10 controls the switching elements Q1 to Q6 so as to stop the supply of electric power to the motor 3. The microcomputer 10 stops driving the motor 3 in step S211 and then returns to step S201.

When it is determined in step S209 that the operation mode is the on-lock mode (step S209: YES), the microcomputer 10 determines whether or not the trigger switch 7 is in the ON state (step S213). When it is determined that the trigger switch 7 is not in the ON state, the microcomputer 10 again determines in step S213. That is, the microcomputer 10 repeats the determination in step S213 until it detects the ON state of the trigger switch 7. On the other hand, when it is determined that the ON state of the trigger switch 7 is detected in step 213 (step S213: YES), the microcomputer 10 controls the motor 3 to stop (step S215).

In other words, even if it is determined in step S205 that the off state of the trigger switch 7 is detected, if it is determined in step S209 that the operation mode is the on-lock mode, the drive of the motor 3 is not stopped. , The driving of the motor 3 is continued until the ON state of the trigger switch 7 is detected in step S213.

After stopping the motor in step S215, the microcomputer 10 determines whether or not the off state of the trigger switch has been detected (step S217). When it is determined that the trigger switch 7 is not in the off state, the microcomputer 10 makes the determination in step 217 again. That is, the microcomputer 10 repeats the determination in step S217 until it detects the off state of the trigger switch 7. When it is determined that the off state of the trigger switch 7 is detected in step S217 (step S217: YES), the microcomputer 10 returns to step S201 and makes a determination.

According to the first embodiment, the microcomputer 10 is configured to be able to switch the operation mode of the screw tightening machine 1 between the on-lock mode and the on-lock release mode, but the present invention is not limited to this. For example, the screw tightening machine 1 includes a lighting unit configured to be able to irradiate light, and the microcomputer 10 has a light ON mode in which the lighting unit irradiates light and a light OFF mode in which the light stops irradiating light. It may be configured so that the operation mode can be switched between and. In this case, the microcomputer 10 may switch the operation mode of the screw tightening machine 1 from the light OFF mode to the light ON mode only when the above-mentioned mode switching operation is performed and the mode switching permission condition is satisfied. Further, for example, the microcomputer 10 has a mode between a "high rotation speed mode" in which the rotation speed of the motor 3 is higher than the "normal mode" and the "on-lock mode", a "low rotation speed mode" in which the rotation speed is lower, and the like. It may be configured to be switchable. In this case, the microcomputer 10 may switch from the "low rotation speed mode" to the "high rotation speed mode" only when the above-mentioned mode switching operation is performed and the mode switching permission condition is satisfied.

As described above, the screw tightening machine 1 detects the motor 3, the trigger switch 7 for controlling the start and stop of the motor 3, the load state of the motor 3, and operates the motor 3 based on the operation on the trigger switch 7. It includes a microcomputer 10 to control. The microcomputer 10 is configured so that the operation mode of the screw tightening machine 1 can be switched between a plurality of modes including an on-lock release mode and an on-lock mode, and the trigger switch 7 is in a state where the operation mode is the on-lock release mode. When the mode switching operation is performed and the mode switching permission condition is satisfied, the operation mode is switched from the on-lock release mode to the on-lock mode, and the mode is set to the trigger switch 7 while the operation mode is the on-lock release mode. If the mode switching permission condition is not satisfied even when the switching operation is performed, the operation mode is maintained in the on-lock release mode.

According to the above configuration, when the mode switching operation is performed on the trigger switch 7, the microcomputer 10 can switch the operation mode according to the load state of the motor 3, thus improving workability. Is possible.

The trigger switch 7 is configured to be switchable between an on state and an off state, and the mode switching operation is an operation of performing an on operation for switching the trigger switch 7 from the on state to the off state a predetermined number of times within a predetermined period TS. ..

Further, the load state after the start of the mode switching operation is the period T1 or the period included in the period T2 starting from the time when the first on operation, which is one of the on operations performed a predetermined number of times in the mode switching operation, is performed. The period T3 or the period t17 to included in the period T4 starting from the time when the motor current in t12 to t14 and the second on operation, which is one of the on operations performed a predetermined number of times in the mode switching operation, is performed. Includes motor current at t19. The period T2 is an example of the "first specific period" in the present invention. The period T1 and the periods t12 to t14 are examples of the "first load monitoring period" in the present invention. The motor currents of the periods T1 and t12 to t14 are examples of the "first load state" in the present invention. The period T4 is an example of the "second specific period" in the present invention. The period T3 and the periods t17 to t19 are examples of the "second load monitoring period" in the present invention. The motor currents of the periods T3 and t17 to t19 are examples of the "second load state" in the present invention.

According to the above configuration, the load state in two periods can be detected as the load information for the motor 3 generated by the on operation, so that the load state of the motor is more reliable than in the case of detecting only the load state in one period. It becomes possible to grasp.

Further, the period T1 is a period starting from the time when the first on operation is performed, and the periods t17 to t19 are periods starting from a time after the time when the second on operation is performed. .. The period T1 is an example of the "first load monitoring period" in the present invention. The periods t17 to t19 are an example of the "second load monitoring period" in the present invention.

Further, the periods t12 to t14 are periods starting from a time point after the first on operation is performed, and the period T3 is a period starting from the time point when the second on operation is performed. .. The periods t12 to t14 are an example of the "first load monitoring period" in the present invention. The period T3 is an example of the "second load monitoring period" in the present invention.

According to the above configuration, it is possible to detect two types of load states, that is, the load state of the motor 3 immediately after the on operation and the motor load state after a lapse of a predetermined period from the on operation. Therefore, only one of the load states can be detected. It is possible to grasp the load state of the motor 3 more reliably than in the case of detection.

Further, the load state after the start of the mode switching operation is the motor in the period T1 included in the period T2 starting from the time when the first on operation, which is one of the on operations performed a predetermined number of times in the mode switching operation, is performed. The current and the motor current in the periods t12 to t14 included in the period T2 are included. The motor current in period T1 is an example of the "third load state" in the present invention. The motor current in the periods t12 to t14 is an example of the "fourth load state" in the present invention. The period T2 is an example of the "third specific period" in the present invention.

According to the above configuration, it is possible to more reliably grasp the load state for the same specific period.

The period T2 is a period starting from the time when the first on operation is performed, and the periods t12 to t14 are periods starting from a predetermined time point after the end of the period T1. The first on operation is an example of the "third on operation" in the present invention. The period T1 is an example of the "third load monitoring period" in the present invention. The periods t12 to t14 are an example of the "fourth load monitoring period" in the present invention.

Further, the microcomputer 10 detects the motor current flowing through the motor 3 as load information, and the mode switching permission condition is that the motor current in the period T1 does not exceed the current threshold I1 and the motor current in the periods t12 to t14 is the current threshold. It is satisfied when the current threshold I2, which is smaller than I1, is not exceeded. The current threshold value I1 is an example of the "first current threshold value" in the present invention. The current threshold value I2 is an example of the "second current threshold value" in the present invention. The mode switching permission condition is an example of the "predetermined condition" in the present invention.

According to the above configuration, the load state can be grasped more reliably by determining the load state of the motor 3 according to the driving state of the motor 3.

The load state after the start of the mode switching operation is the motor current in the period T1 starting from the time when the first on operation in the specific operation is performed, and the period t12 to the starting point starting from the predetermined time after the end of the period T1. The motor current in t14, the motor current in the period T3 starting from the time when the second ON operation in the mode switching operation is performed, and the motor in the periods t17 to t19 starting from the predetermined time after the end of the period T3. Including current. The period T1 is an example of the "fifth load monitoring period" in the present invention. The motor current in period T1 is an example of the "fifth load state" in the present invention. The periods t12 to t14 are an example of the "sixth load monitoring period" in the present invention. The motor current in the periods t12 to t14 is an example of the "sixth load state" in the present invention. The period T3 is an example of the "seventh load monitoring period" in the present invention. The motor current in period T3 is an example of the "seventh load state" in the present invention. The periods t17 to t19 are an example of the "eighth load monitoring period" in the present invention. The motor current in the periods t17 to t19 is an example of the "eighth load state" in the present invention.

According to the above configuration, it is possible to detect the load state for four periods including the two load monitoring periods immediately after the two on operations, so that the load state detection period is less than four. It is possible to reliably grasp the load state of the motor 3.

Further, the microcomputer 10 detects the motor current flowing through the motor 3 as load information, and the mode switching permission condition is that the motor current in the period T1 and the motor current in the period T3 do not exceed the current threshold I1 and the periods t12 to t14. Is satisfied when the motor current in the above and the motor current in the periods t17 to t19 do not exceed the current threshold I2 smaller than the current threshold I3. The current threshold I1 is an example of the "third current threshold" in the present invention. The current threshold I2 is an example of the "fourth current threshold" in the present invention.

According to the above configuration, the load state for four periods including the two load monitoring periods immediately after the two on operations is detected, and the load state after the start of the mode switching operation is determined according to the motor drive status. By performing the above, the load state of the motor can be grasped more reliably.

Further, in the first mode, when the trigger switch 7 is in the ON state, the microcomputer 10 supplies electric power to the motor 3, and when the trigger switch 7 is in the OFF state, the microcomputer 10 supplies electric power to the motor 3. This is the mode to stop. The second mode is a mode in which the microcomputer 10 supplies electric power to the motor 3 even when the trigger switch 7 is off.

According to the above configuration, the operator can work in a mode in which power is supplied to the motor even when the operation unit is off, if necessary, thus improving operability. be able to.

Further, as described above, the screw tightening machine 1 further has an irradiation unit configured to be able to irradiate light, the second mode is a mode in which light is irradiated from the irradiation unit, and the first mode is This is a mode in which the irradiation unit stops irradiating light.

Next, a first modification of the first embodiment will be described. In the first modification, the above-mentioned mode switching permission condition regarding the load state after the mode switching operation is different from that of the first embodiment. Specifically, in the first embodiment described above, if the motor current exceeds the corresponding current threshold value even in one of the four load monitoring periods, it is determined that the mode switching permission condition is not satisfied. In this modification, if the motor current is less than the corresponding threshold value in three or more of the four load monitoring periods, it is determined that the mode switching permission condition is satisfied. That is, even if the motor current is equal to or greater than the corresponding current threshold in one load monitoring period, if the motor current is less than the corresponding current threshold in all other load monitoring periods, the microcomputer 10 is screwed. The operation mode of the tightening machine 1 is switched to the on-lock mode.

For example, as shown in FIG. 7, in the microcomputer 10, even if the motor current in the first period is equal to or higher than the current threshold value I1, the motor currents in the second to fourth periods are less than the corresponding current threshold values I2 to I4. In the case of, the operation mode is switched to the on-lock mode. When the motor current is equal to or higher than a predetermined threshold value in two or more of the first to fourth periods, the microcomputer 10 does not switch the operation mode of the screw tightening machine 1 to the on-lock mode and does not switch to the on-lock release mode. Keep in.

Next, a second modification of the first embodiment will be described. In the second modification, the above-mentioned mode switching permission condition regarding the load state after the mode switching operation is different from that of the first embodiment. Specifically, in the first embodiment described above, if the motor current exceeds the corresponding current threshold value even in one of the four load monitoring periods, it is determined that the mode switching permission condition is not satisfied. In this modified example, if the motor current is less than a predetermined corresponding threshold value in the two load monitoring periods after the second on operation, it is determined that the mode switching permission condition is satisfied. More specifically, the microcomputer 10 detects only the motor currents of the two load monitoring periods after the time when the second on operation is performed, and switches the operation mode if it is less than the corresponding current threshold value of each period. Do. That is, the microcomputer 10 switches the mode if the motor currents of the third period and the fourth period are less than the corresponding current thresholds of the respective periods, but determines the motor currents of the first period and the second period. Not done (Fig. 8).

When the motor currents in the third period and the fourth period are less than a predetermined threshold value, the microcomputer 10 switches the operation mode of the screw tightening machine 1 to the on-lock mode. When the motor current in the third period or the fourth period is equal to or higher than a predetermined threshold value, the microcomputer 10 does not switch the operation mode of the screw tightening machine 1 to the on-lock mode, but maintains the on-lock release mode.

Next, the screw tightening machine 100 according to the second embodiment will be described. In the second embodiment, the mode switching permission condition is different from that of the first embodiment. Specifically, in the first embodiment described above, it was determined that the mode switching permission condition was satisfied when the motor currents of the four load monitoring periods were less than the corresponding current threshold values. In the embodiment of the above, it is determined that the mode switching permission condition is satisfied when the rotation speed of the motor during the four load monitoring periods is larger than the corresponding rotation speed threshold value.

The screw tightening machine 100 of the second embodiment includes a microcomputer 110 instead of the microcomputer 10. The microcomputer 110 detects the rotation speed of the motor 3 in each of the four load monitoring periods as load information, and if it is larger than the corresponding rotation speed threshold value, it is determined that the mode switching permission condition is satisfied, and the operation mode is determined. To switch.

When the motor rotation speed is equal to or higher than a predetermined threshold value, the operator switches the operation mode to the on-lock mode in a state where the tip tool P of the screw tightening machine 100 is not in contact with the screw head (no load state). It is highly probable that the switching operation is being performed. On the other hand, when the motor rotation speed is less than a predetermined threshold value, the operator of the trigger switch 7 performs the additional tightening work in a state where the tip tool P of the screw tightening machine 100 is in contact with the screw head. It is highly probable that the operation of switching between the on state and the off state within a short period of time is being performed. Therefore, in the present embodiment, the microcomputer 10 switches the operation mode to the on-lock mode when the motor rotation speed is less than the predetermined threshold value in all the four load monitoring periods, and the motor rotation speed is equal to or higher than the predetermined threshold value. If there is even one load monitoring period, the operation mode is not switched.

FIG. 9 shows the time-dependent change (vertical axis) of the motor rotation speed (R) and the time-dependent change of the start signal when the operator performs a mode switching operation to switch the operation mode to the on-lock mode in the no-load state. (Vertical axis) is shown (horizontal axis: time t). In FIG. 9, the trigger switch 7 is turned on at the time points t31 and t35, and the trigger switch 7 is turned off at the time points t33 and t38. Further, the second on operation (t35) is performed from the time t31 when the first on operation is performed until the period TS elapses.

In FIG. 9, the four load monitoring periods in which the microcomputer 110 determines the rotation speed of the motor are the ninth period (t31) from the time when the first on operation is performed (t31) to the time when the period T1 elapses (t32). ~ T32), the tenth period (t32 to t34) from the time when the first on operation is performed to the time when the period T2 elapses (t34), and the time when the second on operation is performed (t35). The eleventh period (t35 to t37) from the time when the period T3 elapses (t37), and the twelfth period (t39) from the time when the second on operation is performed to the time when the period T4 elapses (t39) starting from t37. t37 to t39).

As shown in FIG. 9, the rotation speed threshold in the 9th period (t31 to t32) is R1, the rotation speed threshold in the 10th period (t32 to t34) is R2, and the rotation speed in the 11th period (t35 to t37). The number threshold is R3, and the rotation speed threshold in the twelfth period is R4. The rotation speed thresholds R2 and R4 in the tenth period and the twelfth period are set to values larger than the rotation speed thresholds R1 and R3 in the ninth period and the eleventh period immediately after the motor is started. In this embodiment, R1 and R3 are 10,000 rpm, and R2 and R4 are 20,000 rpm.

As shown in FIG. 9, the motor rotation speed is equal to or higher than a predetermined threshold value in all the periods from the 9th to the 12th periods. In this case, the microcomputer 110 is turned on twice within a predetermined period (TS) (time points t31 and t35), and satisfies the mode switching permission condition for the motor rotation speed in all four load monitoring periods. Therefore, the operation mode of the screw tightening machine 100 is switched to the on-lock mode.

On the other hand, in FIG. 10, in a state where the tip tool P of the screw tightening machine 100 is in contact with the screw head, the operator turns the trigger switch 7 on and off within a short period of time in order to perform the tightening work. The time-dependent change (vertical axis) of the motor rotation speed (R) and the time-dependent change (vertical axis) of the start signal when repeated are shown (horizontal axis: time t). As shown in FIG. 10, the trigger switch 7 is turned on at the time points t41 and t45, and the trigger switch 7 is turned off at the time points t43 and t48. Further, the second on operation is performed from the time t41 when the first on operation is performed until the period TS elapses (time point t45).

In FIG. 10, the four load monitoring periods in which the microcomputer 110 determines the motor rotation speed are the thirteenth period (t41-) from the time when the first on operation is performed (t41) to the time when the period T1 elapses (t42). t42), the 14th period (t42 to t44) from the time when the first on operation is performed to the time when the period T2 elapses (t44), starting from the time point t42, and the time when the second on operation is performed (t45). The 15th period (t45 to t47) from the time when the period T3 elapses (t47), and the 16th period (t49) from the time when the second on operation is performed to the time when the period T4 elapses (t49) starting from t47. t47 to t49). As shown in FIG. 10, the motor rotation speed is less than the rotation speed threshold of each period in the entire period from the 13th to the 16th period.

In this case, even if the microcomputer 110 is turned on twice within the predetermined period (TS) (time points t41 and t45), the mode switching permission condition for the motor rotation speed in the load monitoring period is not satisfied. The operation mode of the screw tightening machine 100 is not switched to the on-lock mode, and the on-lock release mode is maintained.

As described above, the microcomputer 110 detects the rotation speed of the motor as load information.

Next, the screw tightening machine 200 according to the third embodiment will be described. In the third embodiment, the mode switching operation is different from that of the first embodiment. Specifically, in the first embodiment described above, the mode switching operation is to perform the on operation twice within 400 ms, but in the present embodiment, the mode switching operation is performed twice within 400 ms. The trigger switch 7 is pulled longer than a predetermined period in the second ON operation. In the present embodiment, the microcomputer 210 is provided instead of the microcomputer 10. The microcomputer 210 is configured to monitor the period during which the operator is pulling the trigger switch 7 (the period during which the operator is in the ON state).

More specifically, in the microcomputer 210, when the operator performs the on operation twice within the predetermined period (TS), the mode switching permission condition for the load state of the motor 3 is satisfied, and the second time. When the interval between the time when the on operation is performed and the time when the second off operation is performed (hereinafter, the on operation period) is longer than the predetermined period (TU), the operation mode of the screw tightening machine 200 is switched. It is configured. In this embodiment, the period TU is 150 ms.

On the other hand, the on-operation period is shorter than the predetermined period even when the operator performs the on-operation twice within the predetermined period (TS) and the mode switching permission condition for the load state of the motor is satisfied. In this case, the microcomputer 210 is configured to maintain the on-lock release mode without switching the operation mode of the screw tightening machine 200.

1, 100, 200 ... Screw tightening machine 3 ... Motor 7 ... Trigger switch 10, 110, 210 ... Microcomputer

Claims (15)

With the motor
An operation unit for controlling the start and stop of the motor, and
An electric tool including a control unit that detects a load state of the motor and controls the motor based on an operation on the operation unit.
The control unit
The operation mode of the power tool is configured to be switchable between a plurality of modes including the first mode and the second mode.
When a specific operation is performed on the operation unit while the operation mode is the first mode and the load state after the start of the specific operation satisfies a predetermined condition, the operation mode is changed from the first mode. Switch to the second mode,
If the predetermined condition is not satisfied even when the specific operation is performed on the operation unit while the operation mode is the first mode, the operation mode is maintained in the first mode. A power tool featuring. The operation unit is configured to be switchable between an on state and an off state.
The power tool according to claim 1, wherein the specific operation is an operation of performing an on operation for switching the operation unit from the on state to the off state a predetermined number of times within a predetermined period. The load state after the start of the specific operation is
The load state in the first load monitoring period included in the first specific period starting from the time when the first on operation, which is one of the on operations performed a predetermined number of times in the specific operation, is performed. 1 load state and
In the load state in the second load monitoring period included in the second specific period starting from the time when the second on operation, which is another one of the on operations performed a predetermined number of times in the specific operation, is performed. The power tool according to claim 2, wherein a second load state is included. The first load monitoring period is a period starting from the time when the first on operation is performed.
The power tool according to claim 3, wherein the second load monitoring period is a period starting from a time point after the time point at which the second on operation is performed. The first load monitoring period is a period starting from a time point after the time point when the first on operation is performed.
The power tool according to claim 3, wherein the second load monitoring period is a period starting from a time when the second on operation is performed. The load state after the start of the specific operation is
The load state in the third load monitoring period included in the third specific period starting from the time when the third on operation, which is one of the on operations performed a predetermined number of times in the specific operation, is performed. 3 load conditions and
The power tool according to claim 2, further comprising a fourth load state, which is the load state in the fourth load monitoring period included in the third specific period. The third load monitoring period is a period starting from the time when the third on operation is performed.
The power tool according to claim 6, wherein the fourth load monitoring period is a period starting from a predetermined time point after the end of the third load monitoring period. The control unit detects the motor current flowing through the motor as the load state, and determines the load state.
Under the predetermined conditions, the motor current in the third load monitoring period indicating the third load state does not exceed the first current threshold value, and the motor current in the fourth load monitoring period indicating the fourth load state is satisfied. The power tool according to claim 7, wherein the power tool is satisfied when the second current threshold value smaller than the first current threshold value is not exceeded. The load state after the start of the specific operation is
The fifth load state, which is the load state in the fifth load monitoring period starting from the time when the first on operation in the specific operation is performed, and
The sixth load state, which is the load state in the sixth load monitoring period starting from a predetermined time point after the end of the fifth load monitoring period, and
The seventh load state, which is the load state in the seventh load monitoring period starting from the time when the second on operation in the specific operation is performed, and
The power tool according to claim 2, further comprising an eighth load state, which is the load state in the eighth load monitoring period starting from a predetermined time point after the end of the seventh load monitoring period. The control unit detects the motor current flowing through the motor as the load state, and determines the load state.
The predetermined conditions are that the motor current in the fifth load monitoring period indicating the fifth load state and the motor current in the seventh load monitoring period indicating the seventh load state do not exceed the third current threshold value. , The fourth current threshold in which the motor current in the sixth load monitoring period indicating the sixth load state and the motor current in the eighth load monitoring period indicating the eighth load state are smaller than the third current threshold. The power tool according to claim 9, wherein the electric tool is satisfied when the value is not exceeded. The power tool according to any one of claims 2 to 7, wherein the control unit detects a motor current flowing through the motor as the load state. The power tool according to any one of claims 2 to 7, wherein the control unit detects the rotation speed of the motor as the load state. In the first mode, when the operation unit is in the ON state, the control unit supplies electric power to the motor, and when the operation unit is in the OFF state, the control unit supplies electric power to the motor. It is a mode to stop the supply of
The electric power according to any one of claims 2 to 12, wherein the second mode is a mode in which the control unit supplies electric power to the motor even when the operation unit is in the off state. tool. It also has an irradiation unit configured to irradiate light.
The second mode is a mode in which light is emitted from the irradiation unit.
The power tool according to any one of claims 1 to 12, wherein the first mode is a mode in which the irradiation unit stops irradiating light. The power tool according to any one of claims 1 to 14, wherein the operation unit is a trigger switch.

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