JP2016158394A - Electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric tool enabling the miniaturization of a device while setting an upper limit voltage to be applicable to a motor higher.SOLUTION: The electric tool includes: a motor including a rotor and a coil to rotate the rotor; switching means for switching on/off power to be supplied to the motor; operation means capable of changing an operation amount; and control means for controlling the switching means. The control means supplies power to the motor through the switching means, so that it can execute first control to rotate the motor. The control means executes step-up operation using the switching means and the coil, and supplies the step-up power to the motor through the switching means, so that it can execute second control to rotate the motor. The control means can selectively execute the first control or the second control according to the operation amount.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power tool.

  Conventionally (see, for example, Patent Document 1), an electric tool that boosts a voltage from a battery pack by a booster circuit and applies the boosted voltage to a motor is known.

JP 2014-69252 A

  The booster circuit needs to be provided with a dedicated booster coil for boosting. In general, since the booster coil is large, there is a problem that the power tool becomes large. On the other hand, assuming a configuration in which a booster circuit is not provided in order to reduce the size of the device, the upper limit of the voltage that can be applied to the motor is lowered, and the upper limit value of the motor rotation speed and the upper limit value of the output torque are also lowered.

  In view of such circumstances, the present invention is intended to provide an electric tool that can increase the upper limit of the voltage that can be applied to a motor without the need for providing a dedicated booster coil. It is another object of the present invention to provide an electric tool that can be downsized.

  To achieve the above object, the present invention provides a motor having a rotor and a coil for rotating the rotor, switching means for turning on and off the power supplied to the motor, operation means capable of changing an operation amount, Control means for controlling the switching means, wherein the control means is capable of executing a first control for rotating the motor by supplying electric power to the motor via the switching means. The means can execute a second control for rotating the motor by performing a boosting operation using the switching means and the coil and supplying the boosted power to the motor via the switching means. The control means is capable of selectively executing the first control and the second control according to the operation amount. It provides an electric tool that.

  According to such a power tool, it is possible to apply an appropriate voltage according to the operation amount to the motor without providing a dedicated booster circuit.

  And further comprising a capacitor, wherein in the second control, the control means accumulates electric charge in the capacitor by the boosted power, and supplies the electric power from the capacitor to the motor via the switching means. The motor is preferably rotated. With such a configuration, the boosted power can be stored in the capacitor.

  Preferably, the control means executes the first control when the operation amount is less than a predetermined value, and executes the second control when the operation amount is equal to or greater than the predetermined value. With such a configuration, appropriate control according to the operation amount can be performed.

  In the second control, it is preferable that the control means sets a target voltage value and boosts the power so that the voltage of the capacitor becomes the target voltage value. With such a configuration, the voltage of the capacitor can be set to a voltage suitable for the operation amount.

  The target voltage value is preferably increased according to the operation amount.

  The control means controls the switching means by supplying a switching signal to the switching means, and in the second control, the control means changes the duty ratio of the switching signal, thereby It is preferable to control the rotation speed. With such a configuration, the rotational speed of the motor can be finely controlled.

It is preferable that a grip portion that can be gripped by a user is further included, and the capacitor is accommodated in the grip portion. With such a configuration, an increase in size of the electric tool can be suppressed.
In order to achieve the above object, the present invention provides a motor having a rotor and a coil that rotates the rotor, and a plurality of switching devices that are connected to one end of the coil and that turn on and off the power supplied from the battery to the motor. An inverter circuit having an element, and a control means for controlling the switching element, wherein a capacitor is connected in parallel to the input side of the inverter circuit, and the positive side of the battery is connected to the positive electrode via a switch and a first diode. The battery is connected to the other end of the coil, the negative electrode side of the battery is connected to the ground of the inverter circuit, and the voltage of the battery is boosted via the switch, the first diode, the coil, and the inverter circuit to An electric tool characterized by being configured to charge a capacitor is provided.
According to such a power tool, since it is not necessary to provide a dedicated booster circuit, the power tool can be downsized. A first path having a second diode connected between a positive electrode of the battery and a positive electrode of the capacitor, and supplying power supplied to the inverter circuit from the battery via the second diode; It is preferable that the battery can be arbitrarily switched between the battery, the switch, the first diode, the coil, and the second path supplied via the capacitor. In addition, when the operation amount of the operation means is less than a predetermined value, electric power is supplied to the inverter circuit via the first path, and the operation amount is predetermined. In the case where the value is greater than or equal to the value, it is preferable that power is supplied to the inverter circuit via the second path.

  According to the electric tool of the present invention, it is possible to increase the upper limit of the voltage that can be applied to the motor without using a dedicated booster coil. In addition, it is possible to provide an electric tool that can be downsized.

Schematic of the cordless power tool of the present embodiment. The circuit diagram which showed the electrical structure of the electric tool of this Embodiment. The graph which showed the voltage with respect to the trigger operation amount of this Embodiment, the duty ratio, and the rotation speed of the motor. FIG. 3A shows a graph showing the number of rotations of the motor with respect to the trigger operation amount, and a graph of voltage (maximum voltage that can be applied to the motor among the battery voltage and the capacitor voltage) with respect to the trigger operation amount. . FIG. 3B shows a graph showing the rotation speed of the motor with respect to the trigger operation amount and a graph of the FET duty ratio with respect to the trigger operation amount. FIG. 3C shows a trigger operation amount and a switch state (ON or OFF). The flowchart of the rotation control of this Embodiment. The flowchart of the pressure | voltage rise control of FIG. 5 is a flowchart of motor control described in FIG. 4. The graph which showed the voltage with respect to the trigger operation amount, the duty ratio, and the rotation speed of the motor in a modification. FIG. 7A shows a graph showing the number of rotations of the motor with respect to the trigger operation amount, and a graph of voltage (maximum voltage that can be applied to the motor among the battery voltage and the capacitor voltage) with respect to the trigger operation amount. . FIG. 7B shows a graph showing the number of rotations of the motor with respect to the trigger operation amount, and a graph of the FET duty ratio with respect to the trigger operation amount. FIG. 7C shows a trigger operation amount and a switch state (ON or OFF).

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view of a cordless power tool 1 according to the present embodiment. The electric power tool 1 is driven by electric power supplied from the battery pack 70. For example, the electric tool 1 is an impact driver. The electric power tool 1 has a case 50. The case 50 has a motor storage part 51, a grip part 52, and a battery attachment part 53. The grip portion 52 is provided between the motor storage portion 51 and the battery attachment portion 53.

  Inside the motor storage 51, the switching substrate 20, the motor 3, and the driving force transmission mechanism 40 are provided. A bit attachment portion 60 is provided in the motor storage portion 51. A bit 80 can be attached to and detached from the bit attachment portion 60. The switching substrate 20 corresponds to the switching means of the present invention.

    The motor 3 is a three-phase brushless DC motor. The motor 3 includes a stator 30, a rotor 35, and a sensor 37. The sensor 37 detects the rotational position (rotation angle) of the rotor 35.

  The driving force transmission mechanism 40 can transmit the rotation of the motor 3 to the bit mounting portion 60.

  The grip portion 52 is configured to be gripped by the user. The grip 5 is provided with a trigger 5. The trigger switch 15 and the capacitor 27 are accommodated in the grip portion 52. The trigger switch 15 is electrically connected to the trigger 5 and can detect an operation amount of the trigger 5 (hereinafter, “trigger operation amount”). The trigger operation amount is an amount indicating the pulling amount of the trigger 5, that is, an amount indicating how much the user has pulled the trigger 5 toward the grip portion 52. The trigger 5 and the trigger switch 15 correspond to the operating means of the present invention.

  The battery attachment part 53 can attach and detach the battery pack 70. A control board 7 is provided inside the battery mounting portion 53. When the battery pack 70 is attached to the battery mounting portion 53, the power of the secondary battery 71 (FIG. 2) inside the battery pack 70 can be supplied to the motor 3. The user grips the grip portion 52 and pulls the trigger 5 to rotate the motor 3. The rotation of the motor 3 is transmitted to the bit mounting portion 60 by the driving force transmission mechanism 40. As a result, the bit mounting portion 60 rotates together with the bit 80.

  FIG. 2 is a circuit diagram showing the electrical connection of the electric power tool 1. FIG. 2 shows a circuit when the battery pack 70 is attached to the electric tool 1. As shown in FIG. 2, the control board 7, the switching board 20 (inverter circuit), the trigger switch 15, the capacitor 27, the stator 30 of the motor 3, and the secondary battery 71 are electrically connected. . This will be described in detail below.

  The control board 7 includes a microcomputer 11, diodes 17 and 19, and a switch 18. The switching substrate 20 has six FETs 21 to 26 and a driver circuit 13. The driver circuit 13 may be provided on the control board 7 instead of the switching board 20.

  The battery pack 70 includes a secondary battery 71. In the present embodiment, the battery pack 70 has a rated voltage of 14.4V. In addition, a rated voltage is not limited to 14.4V, For example, the voltage between 14.4V-36V etc. may be sufficient. Hereinafter, the voltage of the secondary battery 71 is referred to as a battery voltage. The microcomputer 11 corresponds to the control means of the present invention.

  The secondary battery 71 is connected to the capacitor 27 via the diode 17. Specifically, the anode of the diode 17 is connected to the plus terminal of the secondary battery 71, and the cathode of the diode 17 is connected to the plus terminal of the capacitor 27. The secondary battery 71 is connected to the motor 3 through the switch 18 and the diode 19. The diode 19 is connected in parallel with the diode 17. That is, the anode of the diode 19 is connected to the plus terminal of the secondary battery 71 via the switch 18, and the cathode of the diode 19 is connected to the neutral point N of the motor 3. The electric power of the secondary battery 71 is supplied to the capacitor 27 via the diode 17. Further, when the switch 18 is on, the power of the secondary battery 71 can be supplied to the capacitor 27 via the diode 19 (described later).

  The negative terminal of the secondary battery 71 and the negative terminal of the capacitor 27 are connected to the ground.

  In the present embodiment, the stator 30 has three-phase coils 31, 32 and 33. The coils 31, 32, and 33 are connected at a neutral point N by star connection. The rotor 35 can be rotated by electric power stored in the capacitor 27 (charged electric power) or electric power supplied from the secondary battery 71.

  The FETs 21 to 26 are connected in a three-phase bridge format. That is, the source of the FET 21 is connected to the drain of the FET 24 at the connection point P1, the source of the FET 22 is connected to the drain of the FET 25 at the connection point P2, and the source of the FET 23 is connected to the drain of the FET 26 at the connection point P3. The connection points P1, P2, and P3 are connected to the coils 31, 32, and 33, respectively. The drains of the FETs 21, 22, and 23 are connected to the positive side of the capacitor 27, and the sources of the FETs 24, 25, and 26 are connected to the ground. The gates of the FETs 21 to 26 are connected to the driver circuit 13.

  The microcomputer 11 detects the trigger operation amount via the trigger switch 15. The microcomputer 11 controls the switching operation of the FETs 21 to 26 via the driver circuit 13. That is, the microcomputer 11 detects the rotational position of the rotor 35 (FIG. 1) via the sensor 37 (FIG. 1), performs switching control of the FETs 21 to 26 according to the rotational position, and performs predetermined control among the coils 31 to 33. The coil is energized alternately. Specifically, based on the control signal from the microcomputer 11, the driver circuit 13 outputs a switching signal for switching the FETs 21 to 26 on and off. As a result, the coils 31, 32 and 33 are alternately energized to rotate the rotor 35 (FIG. 1).

  The microcomputer 11 detects the trigger operation amount, and changes the duty ratio of the switching signal according to the operation amount. Here, the duty ratio is the ratio of the ON period to the period of the switching signal. By changing the duty ratio, the rotor 35 of the motor 3 can be rotated at a desired torque and rotational speed.

  The microcomputer 11 can control on / off of the switch 18. The switch 18 is, for example, an FET.

  Regardless of whether the switch 18 is on or off, the secondary battery 71 is connected to the capacitor 27 via the diode 17. For this reason, the power of the secondary battery 71 can always be supplied to the capacitor 27.

  When driving the motor 3, by driving the FETs 21 to 26 by a switching operation, the electric power of the capacitor 27 is supplied to the motor 3 and the motor 3 is driven. When zero-phase control (or boost control) described later is not performed, the capacitor 27 is equipotential with the secondary battery 71, and thus it can be said that the motor 3 is driven by electric power from the secondary battery 71.

  In the present embodiment, by turning on the switch 18, zero phase control is performed in which the power of the secondary battery 71 is supplied via the diode 19, the motor 3 (coils 31 to 33), and the FETs 21 to 26. That is, the zero-phase control is a control for boosting the voltage applied to the coils 31 to 33 and generating a high voltage for driving the motor 3 at a high speed. In the present embodiment, the electric power generated by the zero phase control is stored in the capacitor 27.

  Specifically, in the zero phase control, the switch 18 is turned on. Next, the upper arm side FETs 21 to 23 are turned off, and the lower arm side FETs 24 to 26 are turned on. As a result, current flows to the FETs 24, 25, and 26 via the coils 31, 32, and 33, respectively.

  Next, the FETs 24 to 26 are turned off while the FETs 21 to 23 are turned off. Thereby, an electromotive force is generated in the coils 31 to 33. Due to the electromotive force, a current flows through the diode in the FETs 21 to 23 (a diode having an anode on the source side and a cathode on the drain side) to the capacitor 27. At this timing, the FETs 21 to 23 may be turned on without keeping the FETs 21 to 23 off. The capacitor 27 is applied at a voltage higher than the battery voltage by the electromotive force generated from the coils 31 to 33. Thereby, electric charge is accumulated in the capacitor 27, and the voltage of the capacitor 27 becomes higher than the voltage of the secondary battery 71 (14.4 V in the present embodiment).

The above operation is the zero phase control. In the present embodiment, the microcomputer 11 performs control such that the voltage of the capacitor 27 reaches the target voltage by zero-phase control. The target voltage is set as a voltage that can realize the maximum rotation speed of the motor 3. In the present embodiment, the target voltage in the zero-phase control is a value larger than twice the initial voltage of the secondary battery 71. Here, the initial voltage may be a battery voltage when the trigger operation is started (no-load voltage in a state where no load is applied to the motor 3) or a rated voltage of the secondary battery 71. Zero phase control corresponds to the step-up operation of the present invention.
When a sufficient charge cannot be supplied to the capacitor 27 by one zero-phase control, that is, when the voltage Vdc of the capacitor 27 does not reach the target voltage, the zero-phase control is continuously performed several times in a short time. The voltage Vdc of the capacitor 27 may reach the target voltage.

  The switch 18 is turned off in a state where the voltage of the capacitor 27 reaches the target voltage by the zero phase control. In this state, the driver circuit 13 starts the switching operation of the FETs 21 to 26 and rotates the motor 3. As a result, the motor 3 can be driven at high speed and high torque by the electric power stored in the capacitor 27. In the zero-phase control, since current is simultaneously supplied to the coils 31 to 33, the magnetic force generated from the coils 31 to 33 is canceled out, so that the deceleration force does not act on the rotor 35.

  With reference to FIGS. 3A to 3C, the rotation control of the motor 3 according to the present embodiment will be described in more detail. 3A to 3C, the horizontal axis indicates the trigger operation amount. FIG. 3A shows a graph showing the number of rotations of the motor 3 with respect to the trigger operation amount and a graph of a voltage (maximum voltage that can be applied to the motor 3 among the battery voltage and the capacitor voltage) with respect to the trigger operation amount. ing. FIG. 3B shows a graph showing the number of rotations of the motor 3 with respect to the trigger operation amount, and a graph of the duty ratios of the FETs 21 to 26 with respect to the trigger operation amount. The relationship between the trigger operation amount and the duty ratio is stored in advance as a table in which a correspondence relationship is registered, or a relational expression that defines the relationship between the trigger operation amount and the duty ratio, based on the table or the relational expression. , Based on the current trigger operation amount. FIG. 3C shows the trigger operation amount and the state of the switch 18 (ON or OFF).

  As shown in FIG. 3C, in the rotation control, the microcomputer 11 turns off the switch 18 until the trigger operation amount reaches a predetermined amount. That is, zero phase control is not performed in this state. When the trigger operation amount reaches a predetermined amount, the microcomputer 11 turns on the switch 18 to perform zero-phase control.

  Specifically, in FIGS. 3A to 3C, when the trigger operation amount is less than the predetermined amount, the microcomputer 11 performs normal control, and when the trigger operation amount becomes equal to or greater than the predetermined value, performs the boost control. ing. In normal control, the microcomputer 11 supplies the electric power of the secondary battery 71 to the motor 3 by performing the switching operation of the FETs 21 to 26 without performing the zero-phase control. That is, electric power is supplied from the secondary battery 71 to the switching substrate 20 through the first path via the diode 17. In the step-up control, the microcomputer 11 selectively executes the zero-phase control and the switching operation, so that the electric power stored in the capacitor 27 can be supplied to the motor 3. That is, the boosted power is supplied from the secondary battery 71 to the switching substrate 20 through the second path passing through the switch 18, the diode 19, the coils 31 to 33, the inverter substrate 20, and the capacitor 27. The normal control corresponds to the first control of the present invention, and the boost control corresponds to the second control of the present invention.

  The normal control will be described. When the trigger 5 is operated from the state in which the trigger operation amount is zero, the microcomputer 11 performs the switching operation of the FETs 21 to 26 with the switch 18 turned off. Thereby, the motor 3 rotates. As shown in FIG. 3B, the microcomputer 11 increases the duty ratio in proportion to the trigger operation amount until the trigger operation amount reaches a predetermined amount. Note that the battery voltage slightly varies by rotating the motor 3. As shown in FIG. 3A, the battery voltage slightly decreases as the trigger operation amount increases. This schematically shows the fluctuation of the battery voltage. The duty control is performed so that the duty ratio becomes 100% when the trigger operation amount reaches a predetermined amount. In other words, the predetermined amount is an operation amount of the trigger when the duty ratio becomes 100% in the normal control. That is, when the predetermined amount is reached, the rotation speed of the motor 3 is the maximum rotation speed that can be achieved in the normal control, and even if the normal control is maintained, the rotation speed higher than the maximum rotation speed can be realized. I can't. Therefore, boost control is performed in order to realize a rotational speed that is equal to or greater than the maximum rotational speed.

  The boost control will be specifically described. When the operation amount of the trigger reaches a predetermined amount, the microcomputer 11 reduces the duty ratio to the same level as when the motor 3 starts rotating and performs zero-phase control. The voltage of the capacitor 27 reaches the target voltage (or higher than the target voltage) by the zero phase control. If the voltage of the capacitor 27 does not reach the target voltage even if the zero-phase control is performed once, the zero-phase control is continuously performed a plurality of times so that the voltage of the capacitor 27 reaches the target voltage. Thereafter, in order to supply the electric power stored in the capacitor 27 to the motor 3, a switching operation and duty control are performed. Specifically, the microcomputer 11 performs a switching operation while performing duty control that increases the duty ratio in proportion to the trigger operation amount. As shown in FIG. 3A, the voltage of the capacitor 27 decreases as the motor 3 rotates.

  In step-up control, the microcomputer 11 alternately performs zero-phase control and switching operation. That is, when the voltage of the capacitor 27 falls below twice the battery voltage (or the lower limit voltage value) as the motor 3 rotates, the microcomputer 11 performs zero-phase control again at least once. Here, the lower limit voltage value is a value smaller than the target voltage value by a predetermined allowable width. Thereby, the voltage of the capacitor 27 increases, and the voltage of the capacitor 27 can reach the target voltage. Thereafter, the microcomputer 11 performs the switching operation of the FETs 21 to 26 similarly to the normal control, and rotates the motor 3 by the electric power stored in the capacitor 27. When the voltage of the capacitor 27 falls below twice the battery voltage (or the lower limit voltage value), the switching operation is stopped and the zero-phase control is performed again. Thereafter, the switching operation and the zero phase control are similarly repeated. In the present embodiment, the voltage when the rotation speed of the motor 3 becomes maximum is boosted so that the microcomputer 11 is twice the initial voltage. Here, the initial voltage may be a battery voltage when the trigger operation is started, or may be a rated voltage of the secondary battery 71. In the boost control, the duty control is performed so that the duty ratio becomes 100% when the rotation speed of the motor 3 is maximum.

  FIG. 4 is a flowchart of the above rotation control. In S <b> 1 of FIG. 4, the microcomputer 11 receives a signal from the trigger switch 15 and detects a trigger operation amount. The microcomputer 11 sets a target voltage corresponding to the trigger operation amount. Specifically, when the trigger operation amount is smaller than a predetermined value, the target voltage is set to the current battery voltage, and when the trigger operation amount is greater than or equal to the predetermined value, the target voltage is set to be twice or more the initial battery voltage. As described above, the initial battery voltage may be the battery voltage when the trigger operation is started or the rated voltage of the secondary battery 71. Boost control is performed in S3, and motor control is performed in S5. After S5, the process returns to S1.

  FIG. 5 is a flowchart showing details of the boost control in S3. In S31, it is determined whether or not the voltage Vdc of the capacitor 27 is smaller than the target voltage. When the voltage Vdc of the capacitor 27 is smaller than the target voltage (S31: YES), zero phase control is performed. As described above, if the trigger operation amount is equal to or greater than the predetermined amount, the target voltage value is equal to or greater than twice the initial voltage. If the voltage Vdc does not reach the target voltage by one zero-phase control, the zero-phase control is continuously performed a plurality of times until the voltage Vdc reaches the target voltage. When the voltage Vdc is equal to or higher than the target voltage (S31: NO), or when S33 ends, the boost control ends. As described above, when the trigger operation amount is less than the predetermined amount, since the current voltage value is the target voltage value, a negative determination is made in S31.

  FIG. 6 is a flowchart showing details of the motor control in S5. In S51, the microcomputer 11 detects the current trigger operation amount. Note that S51 may be omitted, and the subsequent control may be performed based on the trigger operation amount detected in S1. In S <b> 53, the microcomputer 11 detects the rotational position of the rotor 35 of the motor 3 via the sensor 37. In S55, the microcomputer 11 performs a switching operation based on the detection position. By switching operation, on / off of the FETs 21 to 26 is controlled, and any one of the three-phase coils 31 to 33 is conducted to rotate the motor 3. At this time, duty control corresponding to the trigger operation amount is performed on the switching signal.

  According to the above-described embodiment, the electric power tool 1 boosts the voltage using the coils 31 to 33 without providing a dedicated booster circuit, thereby increasing the voltage higher than the battery voltage according to the trigger operation amount. 3 can be applied. Thereby, the motor 3 can be rotated with the high rotation speed and high torque along a user's request | requirement. In addition, a dedicated booster circuit generally requires a smoothing capacitor and a choke coil. In particular, a large coil is provided. In contrast, in the present application, a dedicated booster circuit is not provided. For this reason, it is not necessary to prepare a space for arranging the capacitor of the booster circuit and the large choke coil, and the power tool 1 can be downsized.

  Also, when the voltage of the capacitor 27 is set higher than the battery voltage, the rotational speed of the motor 3 can be finely controlled by performing duty control.

  The capacitor 27 is provided in the grip portion 52. The capacitor 27 is a relatively large electronic component. However, by providing the capacitor 27 in the grip portion 52, the electric tool 1 can be prevented from increasing in size.

    The power tool 1 according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims.

  In the above embodiment, as shown in FIGS. 3A and 3B, when the trigger operation amount is equal to or larger than the predetermined amount, the capacitor voltage is boosted to the target voltage and then the trigger operation amount is set. Thus, the rotational speed of the motor 3 is increased by increasing the duty ratio. However, as shown in FIGS. 7A to 7C, when the trigger operation amount is equal to or greater than a predetermined value, the target of the capacitor 27 is proportional to the trigger operation amount while the duty ratio is fixed at 100%. You may make it perform the zero phase control which changes a voltage. That is, the target voltage is set to a value corresponding to the target rotational speed of the motor 3. For example, the voltage is boosted up to the target voltage corresponding to the trigger operation amount by changing the number of times that the zero-phase control is continuously performed.

  In the present embodiment, the electric power tool 1 has the three-phase brushless motor 3, but the electric power tool 1 may have the brushless motor 3 having a plurality of phases other than the three-phase.

DESCRIPTION OF SYMBOLS 1 Electric tool 3 Motor 5 Trigger 7 Control board 11 Microcomputer 13 Driver circuit 15 Trigger switch 20 Switching board 18 Switch 27 Capacitor 30 Stator 31-33 Coil 70 Battery pack

Claims (10)

A motor having a rotor and a coil for rotating the rotor;
Switching means for turning on and off the power supplied to the motor;
An operation means capable of changing the operation amount;
Control means for controlling the switching means,
The control means is capable of executing a first control for rotating the motor by supplying electric power to the motor via the switching means,
The control means can execute a boosting operation using the switching means and the coil, and execute a second control for rotating the motor by supplying the boosted power to the motor via the switching means. And
The electric power tool characterized in that the control means can selectively execute the first control and the second control according to the operation amount. Further having a capacitor;
In the second control, the control means accumulates electric charge in the capacitor by the boosted electric power, and supplies the electric power from the capacitor to the motor via the switching means, thereby rotating the motor. The power tool according to claim 1.   The control means executes the first control when the operation amount is less than a predetermined value, and executes the second control when the operation amount is equal to or greater than the predetermined value. The electric tool according to claim 1 or 2.   3. The power tool according to claim 2, wherein, in the second control, the control unit sets a target voltage value and boosts electric power so that a voltage of the capacitor becomes the target voltage value.   The power tool according to claim 4, wherein the target voltage value increases in accordance with the operation amount. The control means controls the switching means by supplying a switching signal to the switching means;
5. The control according to claim 1, wherein, in the second control, the control unit controls the number of revolutions of the motor by changing a duty ratio of the switching signal. 6. Electric tool. It further has a grip part that can be gripped by the user,
The power tool according to claim 2, wherein the capacitor is accommodated in the grip portion. A motor having a rotor and a coil for rotating the rotor;
One end of the coil is connected, an inverter circuit having a plurality of switching elements for turning on and off the power supplied from the battery to the motor;
Control means for controlling the switching element,
Connect a capacitor in parallel to the input side of the inverter circuit,
The positive side of the battery is connected to the other end of the coil via a switch and a first diode, and the negative side of the battery is connected to the ground of the inverter circuit,
A power tool configured to charge the capacitor by boosting the voltage of the battery via the switch, the first diode, the coil, and the inverter circuit. A second diode connected between the positive electrode of the battery and the positive electrode of the capacitor;
A first path for supplying power supplied to the inverter circuit from the battery via the second diode, and a second path for supplying power from the battery via the switch, the first diode, the coil, and the capacitor The power tool according to claim 8, wherein the power tool can be arbitrarily switched. It has an operation means that can change the operation amount,
When the operation amount of the operation means is less than a predetermined value, power is supplied to the inverter circuit via the first path, and when the operation amount is greater than or equal to a predetermined value, the power is supplied via the second path. The power tool according to claim 9, wherein power is supplied to the inverter circuit.

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