WO2010087054A1 - Electric tool - Google Patents

Electric tool Download PDF

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Publication number
WO2010087054A1
WO2010087054A1 PCT/JP2009/066085 JP2009066085W WO2010087054A1 WO 2010087054 A1 WO2010087054 A1 WO 2010087054A1 JP 2009066085 W JP2009066085 W JP 2009066085W WO 2010087054 A1 WO2010087054 A1 WO 2010087054A1
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WIPO (PCT)
Prior art keywords
motor
operation switch
turned
control circuit
switching element
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PCT/JP2009/066085
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French (fr)
Japanese (ja)
Inventor
秀和 須田
卓也 草川
翔洋 大村
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株式会社マキタ
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Publication of WO2010087054A1 publication Critical patent/WO2010087054A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • B25F5/001—Gearings, speed selectors, clutches or the like specially adapted for rotary tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose

Definitions

  • the present invention includes a plurality of switching elements that drive a DC motor, a control circuit that operates the switching elements based on an input signal, and a changeover switch that inputs a signal for switching the rotation direction of the DC motor to the control circuit; And a trigger-type operation switch that inputs a signal for starting the DC motor to the control circuit.
  • the control circuit 106 operates the switching elements FET1 to FET4 based on signals from the operation switch 104 and the changeover switch 105. That is, when the changeover switch 105 is switched to the forward rotation direction and the operation switch 104 is turned on, the switching elements FET1 and FET4 are turned on as shown in FIG.
  • the applied voltage 102 is controlled by a pulse width modulation (PWM) method. As a result, the DC motor 102 rotates in the forward direction.
  • PWM pulse width modulation
  • the present invention has been made to solve the above problems, and the problem to be solved by the present invention is to reduce the size of the switching element and further reduce the cost by minimizing the maximum current flowing through the switching element. It is to plan.
  • the invention according to claim 1 inputs a plurality of switching elements for driving the DC motor, a control circuit for operating the switching elements based on an input signal, and a signal for switching the rotation direction of the DC motor to the control circuit.
  • An electric tool comprising a changeover switch and a trigger type operation switch for inputting a signal for starting the DC motor to the control circuit, wherein the DC motor is rotated by an inertial force after the operation switch is turned off.
  • the rotation speed of the DC motor decreases to 50% or less of the rotation speed when the operation switch is turned on. Operates the switching element based on an ON signal of the operation switch.
  • the DC motor can be operated in the reverse rotation direction when the rotation speed when the DC motor is rotating by inertia force is reduced to 50% or less of the rotation speed when the operation switch is turned on. It becomes. That is, when the electromotive force of the DC motor when rotating by inertia force is halved, the switching element operates and a power supply voltage is applied to the DC motor. For this reason, compared with the conventional method which applies the power supply voltage of reverse polarity in the state with a large electromotive force of a DC motor, the electric current which flows into a switching element at the time of reverse rotation of a DC motor can be restrained small. As a result, it is not necessary to use a switching element for large current as in the prior art, and the switching element can be reduced in size and cost can be reduced.
  • the control circuit controls the switching element based on the ON signal of the operation switch. It is characterized by operating.
  • the switching element is operated by turning on the operation switch, so that the DC motor rotates following the operation of the operation switch. That is, the responsiveness of the electric tool can be maintained.
  • the rotation direction is the same direction, since the polarities of the power source and the DC motor are the same, a very large current does not flow through the switching element.
  • the control circuit operates the switching element based on the ON signal of the operation switch.
  • a plurality of switching elements that drive the DC motor, a control circuit that operates the switching elements based on an input signal, and a signal that switches the rotation direction of the DC motor are input to the control circuit.
  • An electric tool comprising a changeover switch and a trigger type operation switch for inputting a signal for starting the DC motor to the control circuit, wherein the DC motor is rotated by an inertial force after the operation switch is turned off.
  • the control circuit detects the switching element based on the ON signal of the operation switch after a predetermined time from when the operation switch is turned off. It is characterized by operating.
  • the switching element since the current flowing through the switching element during the reverse rotation of the DC motor can be suppressed, it is not necessary to use a switching element for a large current as in the prior art, and the switching element can be reduced in size and cost can be reduced. Can be planned.
  • the electric tool 10 is a rotary tool that uses a DC brushless motor 20 (hereinafter referred to as a DC motor 20) as a drive source.
  • a DC motor 20 a DC brushless motor 20
  • the housing 11 of the electric tool 10 includes a cylindrical housing main body 12 and a grip portion 15 formed so as to protrude from a side portion (lower portion in FIG. 2) of the housing main body 12.
  • the grip portion 15 includes a grip portion 15h that is gripped by the user when using the electric power tool 10, and a lower end portion 15p that is positioned below (tip end side) the grip portion 15h.
  • a trigger-type operation switch 18 is provided at the proximal end of the grip portion 15h, which is pulled by a user with a fingertip.
  • a changeover switch 19 for switching the rotation direction of the DC motor 20 is provided behind the operation switch 18.
  • a connection mechanism (not shown) to which the battery pack 16 is connected is provided at the lower end portion 15p of the grip portion 15.
  • a DC motor 20 is accommodated in the rear part of the housing body 12, and a drive mechanism 24 for amplifying the rotational force of the DC motor 20 and transmitting it to the tip tool 12 is accommodated in front of the DC motor 20.
  • the DC motor 20 includes a rotor 22 having a permanent magnet, a stator 23 having a drive coil 23c, and three magnetic sensors for detecting the positions of the magnetic poles of the rotor 22. 32.
  • the magnetic sensor 32 is attached to the electric circuit board 30 provided at the rear end of the stator 23 at 120 ° intervals so as to surround the rotor 22.
  • the electric circuit board 30 is attached with a three-phase bridge circuit portion 45 of a motor drive circuit 40 which will be described later.
  • the motor drive circuit 40 is an electric circuit for driving the DC motor 20, and as shown in FIG. 1, a three-phase bridge circuit unit 45 including six switching elements 44, an operation switch 18, and a changeover switch. And a control circuit 46 for controlling the switching element 44 of the three-phase bridge circuit unit 45 based on the 19 signals.
  • the three-phase bridge circuit unit 45 includes three (U-phase, V-phase, W-phase) output lines 41, and these output lines 41 correspond to the drive coils 23 c (U-phase, V-phase) corresponding to the DC motor 20. , W phase).
  • the three magnetic sensors 32 are positioned with respect to each drive coil 23c of the DC motor 20 with a phase shifted by 60 °.
  • the switching element 44 of the three-phase bridge circuit unit 45 for example, a field effect transistor (FET) is used. Therefore, in the following description, the six switching elements 44 are represented by FETs 1 to 6.
  • the magnetic sensor 32 is represented by Ha, Hb, and Hc.
  • FIG. 3 is a time chart showing a state when the operation switch 18 is turned on and the DC motor 20 is rotating forward with the changeover switch 19 switched to the forward rotation side.
  • the U-phase positive-side FET 1 is turned on at a timing T1 when the magnetic sensor Ha changes from L to H.
  • the U-phase FET 1 is turned off at the timing T2 when the rotor 22 rotates 120 ° forward (right rotation in FIG. 1) and the magnetic sensor Hb changes from L to H, and the V-phase positive FET 3 Turns on.
  • the V-phase FET 3 is turned off and the W-phase positive-side FET 5 is turned on at the timing T3 when the rotor 22 is rotated 120 ° to the right and the magnetic sensor Hc is changed from L to H.
  • the W-phase FET 5 is turned off at a timing T4 when the rotor 22 further rotates clockwise by 120 ° and the magnetic sensor Ha changes from L to H.
  • the negative-side FET 2 of the U phase is turned on at a timing T5 when the magnetic sensor Ha is changed from H to L, and is turned off at a timing T6 when the magnetic sensor Hb is changed from H to L.
  • the negative-side FET 4 of the V phase is turned on at a timing T6 when the magnetic sensor Hb is changed from H to L, and is turned off at a timing T7 when the magnetic sensor Hc is changed from H to L.
  • the negative-side FET 6 of the W phase is turned on at a timing T7 when the magnetic sensor Hc is changed from H to L, and is turned off at a timing T8 when the magnetic sensor Ha is changed from H to L.
  • FIG. 4 is a time chart showing a state when the operation switch 18 is turned on and the DC motor 20 is reversely rotated in a state where the changeover switch 19 is switched to the reverse side.
  • the U-phase positive-side FET 1 is turned on at a timing T1 when the magnetic sensor Hb changes from L to H.
  • the U-phase FET 1 is turned off and the W-phase positive-side FET 5 is turned off at the timing T2 when the rotor 22 rotates backward by 120 ° (left rotation in FIG. 1) and the magnetic sensor Ha changes from L to H. Turn on.
  • the W-phase FET 5 is turned off and the V-phase positive-side FET 3 is turned on at the timing T3 when the rotor 22 is rotated 120 ° counterclockwise and the magnetic sensor Hc is changed from L to H.
  • the V-phase FET 3 is turned off at a timing T4 when the rotor 22 further rotates counterclockwise by 120 ° and the magnetic sensor Hb changes from L to H.
  • the negative-side FET 2 of the U phase is turned on at a timing T5 when the magnetic sensor Hb is changed from H to L, and is turned off at a timing T6 when the magnetic sensor Ha is changed from H to L.
  • the negative-side FET 6 of the W phase turns on at timing T6 when the magnetic sensor Ha changes from H to L, and turns off at timing T7 when the magnetic sensor Hc changes from H to L.
  • the V-phase negative side FET 4 is turned on at a timing T7 when the magnetic sensor Hc is changed from H to L, and is turned off at a timing T8 when the magnetic sensor Hb is changed from H to L.
  • electromotive forces whose phases are shifted by 120 ° in the order of the U phase, the W phase, and the V are induced in the drive coils 23c of the U phase, the W phase, and the V phase, and the counterclockwise rotating magnetic field is generated by the electromotive force. Will occur.
  • the rotor 22 rotates counterclockwise by the counterclockwise rotating magnetic field (reverse operation of the DC motor 20).
  • step S101 a constant CF representing the rotation direction of the DC motor 20 and a constant NF representing the rotation state of the DC motor 20 are cleared (0).
  • the constant CF is “0” when the rotation direction of the DC motor 20 is the same as the rotation direction in the previous operation, and “1” when the rotation direction is different.
  • the constant NF is “0” when the DC motor 20 is stopped, and “1” when the DC motor 20 is rotating.
  • whether or not the DC motor 20 is stopped is determined based on how the magnetic sensors Ha, Hb, and Hc change.
  • the determination in step S117 is YES, and the process returns to step S103 to determine forward rotation.
  • the determination in step S103 is NO, and the DC motor 20 operates in the reverse rotation direction (step S118).
  • the DC motor 20 can be restarted only after it is stopped.
  • the DC motor 20 cannot be operated in the reverse direction unless the DC motor 20 is stopped. That is, when the electromotive force of the DC motor 20 becomes almost zero, the FETs 1 to 6 operate and a power supply voltage is applied to the DC motor 20. For this reason, compared to the conventional method of applying a power supply voltage having a reverse polarity while the electromotive force of the DC motor 20 is large, the current flowing through the FETs 1 to 6 during the reverse rotation of the DC motor 20 can be suppressed.
  • the switching element FET As a result, it is not necessary to use a switching element FET for large current as in the prior art, and the switching element FET can be reduced in size and cost can be reduced. Further, when the rotation direction is not switched, the switching elements FET1 to FET6 operate following the ON operation of the operation switch 18, and the DC motor 20 is restarted. Thereby, the responsiveness of the electric tool 10 can be maintained.
  • the present invention is not limited to the above-described embodiment, and can be modified without departing from the gist of the present invention.
  • the rotation direction of the DC motor 20 when the rotation direction of the DC motor 20 is switched, an example in which the DC motor 20 can be restarted only after it has stopped has been shown.
  • the rotational speed of the DC motor 20 after the rotational speed of the DC motor 20 is reduced to, for example, 50% or less, 25% or less, or 10% or less of the rotational speed when the operation switch is turned on, the DC motor 20 can be restarted in the reverse direction.
  • the electric tool 10 using the DC brushless motor 20 is illustrated, but the present invention can also be applied to an electric tool using a brushed DC motor.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Direct Current Motors (AREA)
  • Portable Power Tools In General (AREA)

Abstract

Further cost reduction is achieved by reducing the size of a switching element by keeping the maximum current flowing through the switching element as low as possible. An electric tool is provided with a switching element (44) for driving a DC motor, a control circuit (46) for operating the switching element (44), a changeover switch (19), and a trigger-type operation switch (18), wherein when the rotational direction is changed by the changeover switch (19) and the operation switch (18) is turned on again while the DC motor (20) is rotating by inertial force after the operation switch (18) is turned off, the control circuit (46) operates the switching element (44) on the basis of an on signal of the operation switch (18) after the number of rotations of the DC motor (20) decreases to 50 percent or less of the number of rotations thereof when the operation switch (18) is on.

Description

電動工具Electric tool
　本発明は、ＤＣモータを駆動させる複数のスイッチング素子と、入力信号に基づいてそれらのスイッチング素子を動作させる制御回路と、前記ＤＣモータの回転方向を切替える信号を前記制御回路に入力する切替えスイッチと、前記ＤＣモータを起動させる信号を前記制御回路に入力するトリガ形式の操作スイッチとを備える電動工具に関する。 The present invention includes a plurality of switching elements that drive a DC motor, a control circuit that operates the switching elements based on an input signal, and a changeover switch that inputs a signal for switching the rotation direction of the DC motor to the control circuit; And a trigger-type operation switch that inputs a signal for starting the DC motor to the control circuit.
　ネジ締めを行なうドライバ等の電動工具は、例えば、図８（Ａ）に示すように、スイッチの引き代に応じてＤＣモータ１０２の回転数を制御するトリガ形式の操作スイッチ１０４と、前記ＤＣモータ１０２の回転方向を切替える切替えスイッチ１０５とを備えている。
　操作スイッチ１０４と切替えスイッチ１０５の信号は制御回路１０６に入力される。前記制御回路１０６は操作スイッチ１０４、切替えスイッチ１０５の信号に基づいてスイッチング素子ＦＥＴ１～ＦＥＴ４を動作させる。即ち、切替えスイッチ１０５が正転方向に切替えられて操作スイッチ１０４がオンすると、図８（Ｂ）に示すように、スイッチング素子ＦＥＴ１、ＦＥＴ４がオンし、操作スイッチ１０４の引き代に応じてＤＣモータ１０２の印加電圧がパルス幅変調（ＰＷＭ）方式にて制御される。これにより、ＤＣモータ１０２は正転方向に回転するようになる。 As shown in FIG. 8A, for example, an electric tool such as a screwdriver for tightening a screw includes a trigger type operation switch 104 that controls the rotation speed of the DC motor 102 in accordance with the pulling margin of the switch, and the DC motor. And a change-over switch 105 that changes the rotation direction of 102.
Signals from the operation switch 104 and the changeover switch 105 are input to the control circuit 106. The control circuit 106 operates the switching elements FET1 to FET4 based on signals from the operation switch 104 and the changeover switch 105. That is, when the changeover switch 105 is switched to the forward rotation direction and the operation switch 104 is turned on, the switching elements FET1 and FET4 are turned on as shown in FIG. The applied voltage 102 is controlled by a pulse width modulation (PWM) method. As a result, the DC motor 102 rotates in the forward direction.
　次に、この状態で、操作スイッチ１０４をオフすると、図８（Ｃ）に示すように、スイッチング素子ＦＥＴ１、ＦＥＴ４がオフし、ＤＣモータ１０２は慣性力で継続して正転方向に回転する。このとき、ＤＣモータ１０２に通電している電流はスイッチング素子ＦＥＴ２、ＦＥＴ３のダイオードを通して電源に返される。さらに、ＤＣモータ１０２が慣性力で回転しているときに、切替えスイッチ１０５が逆転方向に切替えられて操作スイッチ１０４がオンすると、図８（Ｄ）に示すように、スイッチング素子ＦＥＴ２、ＦＥＴ３がオンする。これにより、ＤＣモータ１０２に対して逆極性の電源電圧が印加され、ＤＣモータ１０２は逆転方向に回転力を受けるようになる。このとき、スイッチング素子ＦＥＴ２、ＦＥＴ３には瞬間的に過大な電流が流れる。
　特許文献１に記載の電動工具では、上記した過大電流に耐えられる仕様のスイッチング素子が使用されている。 Next, when the operation switch 104 is turned off in this state, as shown in FIG. 8C, the switching elements FET1 and FET4 are turned off, and the DC motor 102 continues to rotate in the forward rotation direction with the inertial force. At this time, the current applied to the DC motor 102 is returned to the power supply through the diodes of the switching elements FET2 and FET3. Further, when the changeover switch 105 is switched in the reverse direction and the operation switch 104 is turned on while the DC motor 102 is rotating with inertial force, the switching elements FET2 and FET3 are turned on as shown in FIG. 8D. To do. As a result, a power supply voltage having a reverse polarity is applied to the DC motor 102, and the DC motor 102 receives a rotational force in the reverse direction. At this time, an excessively large current flows instantaneously through the switching elements FET2 and FET3.
In the electric power tool described in Patent Document 1, a switching element having a specification capable of withstanding the excessive current described above is used.
特開２００７－２８３４４７号公報JP 2007-283447 A
　しかし、上記した過大電流に耐えられる仕様のスイッチング素子は大型であり、コスト的にも高くなる。
　本発明は、上記問題点を解決するためになされたものであり、本発明が解決しようとする課題は、スイッチング素子に流れる最大電流を極力低く抑えることで、スイッチング素子を小型化し、さらにコスト低減を図ることである。 However, a switching element having a specification capable of withstanding the excessive current described above is large in size and high in cost.
The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to reduce the size of the switching element and further reduce the cost by minimizing the maximum current flowing through the switching element. It is to plan.
　上記した課題は、各請求項の発明によって解決される。
　請求項１の発明は、ＤＣモータを駆動させる複数のスイッチング素子と、入力信号に基づいてそれらのスイッチング素子を動作させる制御回路と、前記ＤＣモータの回転方向を切替える信号を前記制御回路に入力する切替えスイッチと、前記ＤＣモータを起動させる信号を前記制御回路に入力するトリガ形式の操作スイッチとを備える電動工具であって、前記操作スイッチのオフ後、前記ＤＣモータが慣性力で回転しているときに、前記切替えスイッチにより回転方向が切替えられ、前記操作スイッチが再度オンしたときには、前記ＤＣモータの回転数が前記操作スイッチのオン時の回転数の５０パーセント以下まで低下した後に、前記制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させることを特徴とする。 The above-described problems are solved by the inventions of the claims.
The invention according to claim 1 inputs a plurality of switching elements for driving the DC motor, a control circuit for operating the switching elements based on an input signal, and a signal for switching the rotation direction of the DC motor to the control circuit. An electric tool comprising a changeover switch and a trigger type operation switch for inputting a signal for starting the DC motor to the control circuit, wherein the DC motor is rotated by an inertial force after the operation switch is turned off. When the rotation direction is switched by the change-over switch and the operation switch is turned on again, the rotation speed of the DC motor decreases to 50% or less of the rotation speed when the operation switch is turned on. Operates the switching element based on an ON signal of the operation switch.
　本発明によると、ＤＣモータが慣性力で回転しているときの回転数が操作スイッチのオン時の回転数の５０パーセント以下まで低下したときに、前記ＤＣモータを逆転方向に動作させることが可能となる。即ち、慣性力で回転しているときのＤＣモータの起電力が半減した段階で、スイッチング素子が動作し、前記ＤＣモータに対して電源電圧が加わるようになる。
　このため、ＤＣモータの起電力が大きな状態で逆極性の電源電圧を印加する従来の方法と比較して、ＤＣモータの逆転時にスイッチング素子に流れる電流を小さく抑えることができる。これにより、従来のように大電流用のスイッチング素子を使用する必要がなくなり、スイッチング素子の小型化、さらにコスト低減を図ることができる。 According to the present invention, the DC motor can be operated in the reverse rotation direction when the rotation speed when the DC motor is rotating by inertia force is reduced to 50% or less of the rotation speed when the operation switch is turned on. It becomes. That is, when the electromotive force of the DC motor when rotating by inertia force is halved, the switching element operates and a power supply voltage is applied to the DC motor.
For this reason, compared with the conventional method which applies the power supply voltage of reverse polarity in the state with a large electromotive force of a DC motor, the electric current which flows into a switching element at the time of reverse rotation of a DC motor can be restrained small. As a result, it is not necessary to use a switching element for large current as in the prior art, and the switching element can be reduced in size and cost can be reduced.
　請求項２の発明によると、操作スイッチのオフ後、ＤＣモータが慣性力で回転しているときに、切替えスイッチが操作されないときは、制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させることを特徴とする。
　このように、回転方向が同方向の場合には操作スイッチのオン操作によりスイッチング素子が動作するため、操作スイッチの操作に追従してＤＣモータが回転するようになる。即ち、電動工具の応答性を保持することができる。
　なお、回転方向が同方向の場合には、電源とＤＣモータの極性が等しいため、スイッチング素子にさほど大きな電流は流れない。 According to the second aspect of the present invention, when the changeover switch is not operated when the DC motor is rotating with inertial force after the operation switch is turned off, the control circuit controls the switching element based on the ON signal of the operation switch. It is characterized by operating.
As described above, when the rotation direction is the same direction, the switching element is operated by turning on the operation switch, so that the DC motor rotates following the operation of the operation switch. That is, the responsiveness of the electric tool can be maintained.
When the rotation direction is the same direction, since the polarities of the power source and the DC motor are the same, a very large current does not flow through the switching element.
　請求項３の発明によると、操作スイッチのオフ後、ＤＣモータが慣性力で回転しているときに、切替えスイッチにより回転方向が切替えられ、前記操作スイッチが再度オンしたときには、前記ＤＣモータの回転が停止した後に、制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させることを特徴とする。
　このように、ＤＣモータの逆転は、そのＤＣモータの停止後、即ち、前記ＤＣモータの起電力がほぼ零になった段階で行われるため、前記ＤＣモータの逆転時にスイッチング素子に流れる電流をさらに小さく抑えることができる。 According to the invention of claim 3, after the operation switch is turned off, when the DC motor is rotated by inertial force, the rotation direction is switched by the changeover switch, and when the operation switch is turned on again, the rotation of the DC motor is turned on. After the stop, the control circuit operates the switching element based on the ON signal of the operation switch.
As described above, since the reverse rotation of the DC motor is performed after the DC motor is stopped, that is, at the stage where the electromotive force of the DC motor becomes almost zero, the current flowing through the switching element during the reverse rotation of the DC motor is further increased. It can be kept small.
　請求項４の発明は、ＤＣモータを駆動させる複数のスイッチング素子と、入力信号に基づいてそれらのスイッチング素子を動作させる制御回路と、前記ＤＣモータの回転方向を切替える信号を前記制御回路に入力する切替えスイッチと、前記ＤＣモータを起動させる信号を前記制御回路に入力するトリガ形式の操作スイッチとを備える電動工具であって、前記操作スイッチのオフ後、前記ＤＣモータが慣性力で回転しているときに、前記切替えスイッチにより回転方向が切替えられ、前記操作スイッチが再度オンしたときには、前記操作スイッチがオフした時から所定時間後に、前記制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させることを特徴とする。 According to a fourth aspect of the present invention, a plurality of switching elements that drive the DC motor, a control circuit that operates the switching elements based on an input signal, and a signal that switches the rotation direction of the DC motor are input to the control circuit. An electric tool comprising a changeover switch and a trigger type operation switch for inputting a signal for starting the DC motor to the control circuit, wherein the DC motor is rotated by an inertial force after the operation switch is turned off. When the direction of rotation is switched by the change-over switch and the operation switch is turned on again, the control circuit detects the switching element based on the ON signal of the operation switch after a predetermined time from when the operation switch is turned off. It is characterized by operating.
　本発明によると、ＤＣモータの逆転時にスイッチング素子に流れる電流を小さく抑えることができるため、従来のように大電流用のスイッチング素子を使用する必要がなくなり、スイッチング素子の小型化、さらにコスト低減を図ることができる。 According to the present invention, since the current flowing through the switching element during the reverse rotation of the DC motor can be suppressed, it is not necessary to use a switching element for a large current as in the prior art, and the switching element can be reduced in size and cost can be reduced. Can be planned.
本発明の実施形態１に係る電動工具におけるモータ駆動回路の構成を表す図面である。It is drawing showing the structure of the motor drive circuit in the electric tool which concerns on Embodiment 1 of this invention. 本発明の実施形態１に係る電動工具の模式側面図である。It is a model side view of the electric tool which concerns on Embodiment 1 of this invention. 前記モータ駆動回路によりＤＣモータを正転動作させたときのタイムチャート図である。It is a time chart figure when a DC motor is normally rotated by the motor drive circuit. 前記モータ駆動回路によりＤＣモータを逆転動作させたときのタイムチャート図である。It is a time chart figure when a DC motor is reversely operated by the motor drive circuit. 前記モータ駆動回路によりＤＣモータを正転方向から逆転方向に再起動させたときのタイムチャート図である。It is a time chart when the DC motor is restarted from the normal rotation direction to the reverse rotation direction by the motor drive circuit. 前記モータ駆動回路によりＤＣモータを正転状態で再起動させたときのタイムチャート図である。It is a time chart figure when a DC motor is restarted in the normal rotation state by the motor drive circuit. 本発明の実施形態１に係る電動工具の制御フローチャートである。It is a control flowchart of the electric tool which concerns on Embodiment 1 of this invention. 従来の電動工具におけるモータ駆動回路の構成を表す模式図（Ａ図）、スイッチング素子の切替え状態を表す模式図（Ｂ図、Ｃ図、Ｄ図）である。It is a schematic diagram (A figure) showing the structure of the motor drive circuit in the conventional electric tool, and a schematic diagram (B figure, C figure, D figure) showing the switching state of a switching element.
［実施形態１］
　以下、図１から図７に基づいて、本発明の実施形態１に係る電動工具の説明を行なう。
＜電動工具の概要について＞
　本実施形態に係る電動工具１０は、ＤＣブラシレスモータ２０（以下、ＤＣモータ２０という）を駆動源とする回転工具である。図２に示すように、電動工具１０のハウジング１１は、筒状のハウジング本体部１２と、そのハウジング本体部１２の側部（図２では下部）から突出するように形成されたグリップ部１５とから構成されている。グリップ部１５は、使用者が電動工具１０を使用する際に握る握り部位１５ｈと、その握り部位１５ｈよりも下側（先端側）に位置する下端部位１５ｐとから構成されている。そして、握り部位１５ｈの基端部に使用者が指先で引き操作するトリガ形式の操作スイッチ１８が設けられている。また、操作スイッチ１８の後方にはＤＣモータ２０の回転方向を切替える切替えスイッチ１９が設けられている。さらに、グリップ部１５の下端部位１５ｐには、電池パック１６が連結される連結機構（図示省略）が設けられている。 [Embodiment 1]
Hereinafter, based on FIGS. 1-7, the electric tool which concerns on Embodiment 1 of this invention is demonstrated.
<About the outline of electric tools>
The electric tool 10 according to the present embodiment is a rotary tool that uses a DC brushless motor 20 (hereinafter referred to as a DC motor 20) as a drive source. As shown in FIG. 2, the housing 11 of the electric tool 10 includes a cylindrical housing main body 12 and a grip portion 15 formed so as to protrude from a side portion (lower portion in FIG. 2) of the housing main body 12. It is composed of The grip portion 15 includes a grip portion 15h that is gripped by the user when using the electric power tool 10, and a lower end portion 15p that is positioned below (tip end side) the grip portion 15h. A trigger-type operation switch 18 is provided at the proximal end of the grip portion 15h, which is pulled by a user with a fingertip. A changeover switch 19 for switching the rotation direction of the DC motor 20 is provided behind the operation switch 18. Furthermore, a connection mechanism (not shown) to which the battery pack 16 is connected is provided at the lower end portion 15p of the grip portion 15.
　ハウジング本体部１２の後部にはＤＣモータ２０が収納されており、そのＤＣモータ２０の前方にＤＣモータ２０の回転力を増幅して先端工具１２に伝達するための駆動機構２４が収納されている。
　ＤＣモータ２０は、図１等に示すように、永久磁石を備える回転子２２と、駆動コイル２３ｃを備える固定子２３と、前記回転子２２の磁極の位置を検出するための三個の磁気センサ３２とから構成されている。磁気センサ３２は、図２に示すように、固定子２３の後端部に設けられた電気回路基板３０に回転子２２を囲むように120°間隔で取付けられている。また、前記電気回路基板３０には、後記するモータ駆動回路４０の三相ブリッジ回路部４５等が取付けられている。 A DC motor 20 is accommodated in the rear part of the housing body 12, and a drive mechanism 24 for amplifying the rotational force of the DC motor 20 and transmitting it to the tip tool 12 is accommodated in front of the DC motor 20. .
As shown in FIG. 1 and the like, the DC motor 20 includes a rotor 22 having a permanent magnet, a stator 23 having a drive coil 23c, and three magnetic sensors for detecting the positions of the magnetic poles of the rotor 22. 32. As shown in FIG. 2, the magnetic sensor 32 is attached to the electric circuit board 30 provided at the rear end of the stator 23 at 120 ° intervals so as to surround the rotor 22. The electric circuit board 30 is attached with a three-phase bridge circuit portion 45 of a motor drive circuit 40 which will be described later.
＜モータ駆動回路４０ついて＞
　モータ駆動回路４０は、ＤＣモータ２０を駆動させるための電気回路であり、図１に示すように、６個のスイッチング素子４４から構成された三相ブリッジ回路部４５と、操作スイッチ１８と切替えスイッチ１９の信号に基づいて前記三相ブリッジ回路部４５のスイッチング素子４４を制御する制御回路４６とを備えている。
　三相ブリッジ回路部４５は、三本（Ｕ相、Ｖ相、Ｗ相）の出力線４１を備えており、それらの出力線４１がＤＣモータ２０の対応する駆動コイル２３ｃ（Ｕ相、Ｖ相、Ｗ相）に接続されている。また、３個の磁気センサ３２は、ＤＣモータ２０の各々の駆動コイル２３ｃに対してそれぞれ60°位相をずらした状態で位置決めされている。
　ここで、三相ブリッジ回路部４５のスイッチング素子４４としては、例えば、電界効果型トランジスタ（ＦＥＴ）が使用される。このため、以下の説明では、６台のスイッチング素子４４をＦＥＴ１～６で表すことにする。また、磁気センサ３２をＨａ、Ｈｂ、Ｈｃで表すことにする。 <About the motor drive circuit 40>
The motor drive circuit 40 is an electric circuit for driving the DC motor 20, and as shown in FIG. 1, a three-phase bridge circuit unit 45 including six switching elements 44, an operation switch 18, and a changeover switch. And a control circuit 46 for controlling the switching element 44 of the three-phase bridge circuit unit 45 based on the 19 signals.
The three-phase bridge circuit unit 45 includes three (U-phase, V-phase, W-phase) output lines 41, and these output lines 41 correspond to the drive coils 23 c (U-phase, V-phase) corresponding to the DC motor 20. , W phase). In addition, the three magnetic sensors 32 are positioned with respect to each drive coil 23c of the DC motor 20 with a phase shifted by 60 °.
Here, as the switching element 44 of the three-phase bridge circuit unit 45, for example, a field effect transistor (FET) is used. Therefore, in the following description, the six switching elements 44 are represented by FETs 1 to 6. The magnetic sensor 32 is represented by Ha, Hb, and Hc.
＜モータ駆動回路４０の動作について＞
　次に、図３から図６に基づいてモータ駆動回路４０の動作について簡単に説明する。
　図３は、切替えスイッチ１９が正転側に切替えられた状態で操作スイッチ１８がオンし、ＤＣモータ２０が正転しているときの状態を表すタイムチャートである。
　正転時には、図３に示すように、磁気センサＨａがＬ→Ｈに変化したタイミングＴ１でＵ相の正側のＦＥＴ１がオンする。また、この状態から回転子２２が120°正転（図１において右回転）して磁気センサＨｂがＬ→Ｈに変化したタイミングＴ２でＵ相のＦＥＴ１がオフし、Ｖ相の正側のＦＥＴ３がオンする。さらに、回転子２２が120°右回転して磁気センサＨｃがＬ→Ｈに変化したタイミングＴ３でＶ相のＦＥＴ３がオフし、Ｗ相の正側のＦＥＴ５がオンする。Ｗ相のＦＥＴ５は、回転子２２がさらに120°右回転して磁気センサＨａがＬ→Ｈに変化したタイミングＴ４でオフする。
　また、Ｕ相の負側のＦＥＴ２は磁気センサＨａがＨ→Ｌに変化したタイミングＴ５でオンし、磁気センサＨｂがＨ→Ｌに変化したタイミングＴ６でオフする。Ｖ相の負側のＦＥＴ４は磁気センサＨｂがＨ→Ｌに変化したタイミングＴ６でオンし、磁気センサＨｃがＨ→Ｌに変化したタイミングＴ７でオフする。Ｗ相の負側のＦＥＴ６は磁気センサＨｃがＨ→Ｌに変化したタイミングＴ７でオンし、磁気センサＨａがＨ→Ｌに変化したタイミングＴ８でオフする。
　これにより、Ｕ相、Ｖ相、Ｗ相の各駆動コイル２３ｃには、Ｕ相、Ｖ相、Ｗ相の順番に位相が120°ずれた起電力が誘導され、前記起電力により右回りの回転磁界が発生する。そして、前記右回りの回転磁界により回転子２２が右回に回転するようになる（ＤＣモータ２０の正転動作）。 <Operation of Motor Drive Circuit 40>
Next, the operation of the motor drive circuit 40 will be briefly described with reference to FIGS.
FIG. 3 is a time chart showing a state when the operation switch 18 is turned on and the DC motor 20 is rotating forward with the changeover switch 19 switched to the forward rotation side.
During forward rotation, as shown in FIG. 3, the U-phase positive-side FET 1 is turned on at a timing T1 when the magnetic sensor Ha changes from L to H. Further, from this state, the U-phase FET 1 is turned off at the timing T2 when the rotor 22 rotates 120 ° forward (right rotation in FIG. 1) and the magnetic sensor Hb changes from L to H, and the V-phase positive FET 3 Turns on. Further, the V-phase FET 3 is turned off and the W-phase positive-side FET 5 is turned on at the timing T3 when the rotor 22 is rotated 120 ° to the right and the magnetic sensor Hc is changed from L to H. The W-phase FET 5 is turned off at a timing T4 when the rotor 22 further rotates clockwise by 120 ° and the magnetic sensor Ha changes from L to H.
Further, the negative-side FET 2 of the U phase is turned on at a timing T5 when the magnetic sensor Ha is changed from H to L, and is turned off at a timing T6 when the magnetic sensor Hb is changed from H to L. The negative-side FET 4 of the V phase is turned on at a timing T6 when the magnetic sensor Hb is changed from H to L, and is turned off at a timing T7 when the magnetic sensor Hc is changed from H to L. The negative-side FET 6 of the W phase is turned on at a timing T7 when the magnetic sensor Hc is changed from H to L, and is turned off at a timing T8 when the magnetic sensor Ha is changed from H to L.
As a result, electromotive forces whose phases are shifted by 120 ° in the order of the U phase, the V phase, and the W phase are induced in the U-phase, V-phase, and W-phase drive coils 23c, and the electromotive force rotates clockwise. Magnetic field is generated. Then, the rotor 22 rotates clockwise by the clockwise rotating magnetic field (forward rotation operation of the DC motor 20).
　図４は、切替えスイッチ１９が逆転側に切替えられた状態で操作スイッチ１８がオンし、ＤＣモータ２０が逆転しているときの状態を表すタイムチャートである。
　逆転時には、図４に示すように、磁気センサＨｂがＬ→Ｈに変化したタイミングＴ１でＵ相の正側のＦＥＴ１がオンする。また、この状態から回転子２２が120°逆転（図１において左回転）して磁気センサＨａがＬ→Ｈに変化したタイミングＴ２でＵ相のＦＥＴ１がオフし、Ｗ相の正側のＦＥＴ５がオンする。さらに、回転子２２が120°左回転して磁気センサＨｃがＬ→Ｈに変化したタイミングＴ３でＷ相のＦＥＴ５がオフし、Ｖ相の正側のＦＥＴ３がオンする。Ｖ相のＦＥＴ３は、回転子２２がさらに120°左回転して磁気センサＨｂがＬ→Ｈに変化したタイミングＴ４でオフする。
　また、Ｕ相の負側のＦＥＴ２は磁気センサＨｂがＨ→Ｌに変化したタイミングＴ５でオンし、磁気センサＨａがＨ→Ｌに変化したタイミングＴ６でオフする。Ｗ相の負側のＦＥＴ６は磁気センサＨａがＨ→Ｌに変化したタイミングＴ６でオンし、磁気センサＨｃがＨ→Ｌに変化したタイミングＴ７でオフする。Ｖ相の負側のＦＥＴ４は磁気センサＨｃがＨ→Ｌに変化したタイミングＴ７でオンし、磁気センサＨｂがＨ→Ｌに変化したタイミングＴ８でオフする。
　これにより、Ｕ相、Ｗ相、Ｖ相の各駆動コイル２３ｃには、Ｕ相、Ｗ相、Ｖの順番に位相が120°ずれた起電力が誘導され、前記起電力により左回りの回転磁界が発生する。そして、前記左回りの回転磁界により回転子２２が左回に回転するようになる（ＤＣモータ２０の逆転動作）。 FIG. 4 is a time chart showing a state when the operation switch 18 is turned on and the DC motor 20 is reversely rotated in a state where the changeover switch 19 is switched to the reverse side.
At the time of reverse rotation, as shown in FIG. 4, the U-phase positive-side FET 1 is turned on at a timing T1 when the magnetic sensor Hb changes from L to H. Further, from this state, the U-phase FET 1 is turned off and the W-phase positive-side FET 5 is turned off at the timing T2 when the rotor 22 rotates backward by 120 ° (left rotation in FIG. 1) and the magnetic sensor Ha changes from L to H. Turn on. Further, the W-phase FET 5 is turned off and the V-phase positive-side FET 3 is turned on at the timing T3 when the rotor 22 is rotated 120 ° counterclockwise and the magnetic sensor Hc is changed from L to H. The V-phase FET 3 is turned off at a timing T4 when the rotor 22 further rotates counterclockwise by 120 ° and the magnetic sensor Hb changes from L to H.
Further, the negative-side FET 2 of the U phase is turned on at a timing T5 when the magnetic sensor Hb is changed from H to L, and is turned off at a timing T6 when the magnetic sensor Ha is changed from H to L. The negative-side FET 6 of the W phase turns on at timing T6 when the magnetic sensor Ha changes from H to L, and turns off at timing T7 when the magnetic sensor Hc changes from H to L. The V-phase negative side FET 4 is turned on at a timing T7 when the magnetic sensor Hc is changed from H to L, and is turned off at a timing T8 when the magnetic sensor Hb is changed from H to L.
As a result, electromotive forces whose phases are shifted by 120 ° in the order of the U phase, the W phase, and the V are induced in the drive coils 23c of the U phase, the W phase, and the V phase, and the counterclockwise rotating magnetic field is generated by the electromotive force. Will occur. The rotor 22 rotates counterclockwise by the counterclockwise rotating magnetic field (reverse operation of the DC motor 20).
　次に、ＤＣモータ２０が正転しているときに、操作スイッチ１８をオフし、ＤＣモータ２０が慣性力で正転方向に回転しているときに、仮に、ＤＣモータ２０を逆転させたときの状態を、図５のタイムチャートに基づいて説明する。
　図５のタイミングＴ１の時点で操作スイッチ１８をオフすると、この時点でＦＥＴ１～６がオフして、ＤＣモータ２０の各相の駆動コイル２３ｃには電源電圧が印加されなくなる。しかし、ＤＣモータ２０の回転子２２は慣性力で正転方向（右回り）に回転しているため、各相の駆動コイル２３ｃには起電力が発生している。図５の下側には代表してＵ相の起電力を例示している。この状態で、回転方向を切替え（タイミングＴ２参照）、操作スイッチ１８をオンすると（タイミングＴ３）、タイミングＴ３では磁気センサＨｂがＨレベル状態であるため、Ｕ相の正側のＦＥＴ１とＶ相の負側のＦＥＴ４がオンする（図４のタイムチャート参照）。これにより、例えば、タイミングＴ３においてＵ相におけるＤＣモータ２０の起電力の状態と三相ブリッジ回路部４５が印加する電圧の状態との電位差に起因してＦＥＴ１とＦＥＴ４とには過大な電流が流れるようになる。
　これに対し、回転方向を変えずに再起動する場合には、図６に示すように、再起動時（タイミングＴ１）における電位差は小さいため、ＦＥＴ３とＦＥＴ２とに過大な電流が流れるようなことがない。 Next, when the DC motor 20 is rotating forward, the operation switch 18 is turned off, and when the DC motor 20 is rotating in the forward rotation direction by inertia force, the DC motor 20 is reversely rotated. This state will be described based on the time chart of FIG.
When the operation switch 18 is turned off at the timing T1 in FIG. 5, the FETs 1 to 6 are turned off at this time, and the power supply voltage is not applied to the drive coils 23c of the respective phases of the DC motor 20. However, since the rotor 22 of the DC motor 20 is rotating in the normal rotation direction (clockwise) by the inertial force, an electromotive force is generated in the drive coil 23c of each phase. The lower side of FIG. 5 illustrates the U-phase electromotive force as a representative. In this state, when the rotation direction is switched (see timing T2) and the operation switch 18 is turned on (timing T3), the magnetic sensor Hb is in the H level state at timing T3. The negative FET 4 is turned on (see the time chart in FIG. 4). Thereby, for example, an excessive current flows in the FET 1 and the FET 4 due to the potential difference between the state of the electromotive force of the DC motor 20 in the U phase and the state of the voltage applied by the three-phase bridge circuit unit 45 at the timing T3. It becomes like this.
On the other hand, when restarting without changing the rotation direction, as shown in FIG. 6, since the potential difference at the time of restarting (timing T1) is small, an excessive current flows through FET3 and FET2. There is no.
＜本実施形態に係る電動工具１０の制御方法について＞
　次に、図７のフローチャートに基づいて本実施形態に係る電動工具１０の制御方法について説明する。
　先ず、ステップＳ１０１でＤＣモータ２０の回転方向を表す定数ＣＦとＤＣモータ２０の回転状態を表す定数ＮＦとをクリア（０）する。ここで、定数ＣＦは、ＤＣモータ２０の回転方向が前回の動作時における回転方向と同じ場合には「０」、異なる場合には「１」となる。また、定数ＮＦは、ＤＣモータ２０が停止中であれば「０」、回転中であれば「１」となる。ここで、ＤＣモータ２０が停止したか否かは、磁気センサＨａ，Ｈｂ，Ｈｃの変化具合により判定する。
　操作スイッチ１８（Ｔｒｉｇ）が引き操作されて（ステップＳ１０２　ＹＥＳ）、切替えスイッチ１９が正転方向に設定されていると（ステップＳ１０３　ＹＥＳ）、ＤＣモータ２０が正転する（ステップＳ１０４、ステップＳ１０５　ＹＥＳ）。これにより、定数ＮＦ＝１になる（ステップＳ１０６）。
　この状態で、操作スイッチ１８がオフすると（ステップ１０８　ＹＥＳ）、ＤＣモータ２０は慣性力で正転方向に回転を維持するようになる。 <About the control method of the electric tool 10 according to the present embodiment>
Next, a control method of the electric power tool 10 according to the present embodiment will be described based on the flowchart of FIG.
First, in step S101, a constant CF representing the rotation direction of the DC motor 20 and a constant NF representing the rotation state of the DC motor 20 are cleared (0). Here, the constant CF is “0” when the rotation direction of the DC motor 20 is the same as the rotation direction in the previous operation, and “1” when the rotation direction is different. The constant NF is “0” when the DC motor 20 is stopped, and “1” when the DC motor 20 is rotating. Here, whether or not the DC motor 20 is stopped is determined based on how the magnetic sensors Ha, Hb, and Hc change.
When the operation switch 18 (Trig) is pulled (YES in step S102) and the changeover switch 19 is set in the forward rotation direction (YES in step S103), the DC motor 20 rotates forward (step S104, step S105 YES). ). As a result, the constant NF = 1 (step S106).
In this state, when the operation switch 18 is turned off (YES in Step 108), the DC motor 20 maintains its rotation in the forward rotation direction by the inertial force.
　この状態で、切替えスイッチ１９が逆転方向に操作されると（ステップＳ１０９　ＹＥＳ）、定数ＣＦ＝１になる（ステップＳ１１０）。ＤＣモータ２０が慣性力で回転している場合には、ステップＳ１１２の判断がＮＯとなり、定数ＮＦ＝１となる（ステップＳ１１４）。この状態で、操作スイッチ１８をオン操作しても（ステップＳ１１５　ＹＥＳ）、定数ＣＦと定数ＮＦは「１」であるため、処理はステップＳ１１６からステップＳ１１７を経由して、ステップＳ１０９に戻される。即ち、ＤＣモータ２０が慣性力で回転している間（ＮＦ＝１である間）はステップＳ１１５、Ｓ１１６、Ｓ１１７、Ｓ１０９・・・Ｓ１１５の処理が繰り返し行われ、ＤＣモータ２０の逆転は行われない。 In this state, when the changeover switch 19 is operated in the reverse direction (YES in step S109), the constant CF = 1 (step S110). If the DC motor 20 is rotating with inertial force, the determination in step S112 is NO and the constant NF = 1 (step S114). Even if the operation switch 18 is turned on in this state (YES in step S115), since the constant CF and the constant NF are “1”, the process returns from step S116 to step S109 via step S117. That is, while the DC motor 20 is rotating with inertial force (while NF = 1), the processes of steps S115, S116, S117, S109,... S115 are repeated, and the reverse rotation of the DC motor 20 is performed. Absent.
　しかし、ＤＣモータ２０が停止すると（ステップＳ１１２　ＹＥＳ）、定数ＮＦ＝０になり（ステップＳ１１３）、操作スイッチ１８をオン操作すると（ステップＳ１１５　ＹＥＳ）、ステップＳ１１７でＮＦ＝０が判定される。現段階では、ＮＦ＝０であるからステップＳ１１７の判断がＹＥＳになり、処理はステップＳ１０３に戻されて正転判定される。前述のように、切替えスイッチ１９が逆転方向に操作されているため、ステップＳ１０３の判定はＮＯになり、ＤＣモータ２０は逆転方向に動作するようになる（ステップＳ１１８）。
　このように、ＤＣモータ２０の回転方向を切替える場合には、ＤＣモータ２０が停止後でなければ再起動できないように構成されている。 However, when the DC motor 20 is stopped (step S112 YES), the constant NF = 0 is set (step S113), and when the operation switch 18 is turned on (step S115 YES), NF = 0 is determined in step S117. At the current stage, since NF = 0, the determination in step S117 is YES, and the process returns to step S103 to determine forward rotation. As described above, since the changeover switch 19 is operated in the reverse rotation direction, the determination in step S103 is NO, and the DC motor 20 operates in the reverse rotation direction (step S118).
As described above, when the rotation direction of the DC motor 20 is switched, the DC motor 20 can be restarted only after it is stopped.
　また、ステップ１１８でＤＣモータ２０を逆転動作させた後、操作スイッチ１８をオフすると（ステップ１２２　ＹＥＳ）、ＤＣモータ２０は慣性力で逆転方向に回転を維持する。このとき、切替えスイッチ１９が操作されなければ（ステップＳ１０９　ＮＯ）、定数ＣＦ＝０になる（ステップＳ１１１）。
　そして、ＤＣモータ２０が慣性力で逆転している状態で（ステップＳ１１２　ＮＯ）、操作スイッチ１８がオン操作されると（ステップＳ１１５　ＹＥＳ）、定数ＣＦ＝０であるからステップＳ１１６の判断がＹＥＳになり、処理はステップＳ１０３に戻される。そして、ステップＳ１１８で再びＤＣモータ２０の逆転動作が行われる。
　このように、ＤＣモータ２０が慣性力で回転している状態であっても、同方向に回転させる場合には操作スイッチ１８の引き操作（オン操作）に追従してＤＣモータ２０を再起動できるようになる。 If the operation switch 18 is turned off after the DC motor 20 is rotated in the reverse direction in step 118 (YES in step 122), the DC motor 20 maintains the rotation in the reverse direction by the inertial force. At this time, if the changeover switch 19 is not operated (NO in step S109), the constant CF = 0 (step S111).
Then, when the operation switch 18 is turned on (step S115: YES) while the DC motor 20 is reversely rotated by the inertial force (step S112: YES), the constant CF = 0, so the determination in step S116 is YES. Thus, the process returns to step S103. In step S118, the reverse operation of the DC motor 20 is performed again.
As described above, even when the DC motor 20 is rotated by the inertial force, the DC motor 20 can be restarted following the pulling operation (ON operation) of the operation switch 18 when rotating in the same direction. It becomes like this.
＜本実施形態に係る電動工具１０の長所について＞
　本実施形態に係る電動工具１０によると、ＤＣモータ２０が停止した後でなければ、ＤＣモータ２０を逆転方向に動作させることができない。即ち、ＤＣモータ２０の起電力がほぼ零になった段階で、ＦＥＴ１～６が動作し、ＤＣモータ２０に対して電源電圧が加わるようになる。
　このため、ＤＣモータ２０の起電力が大きな状態で逆極性の電源電圧を印加する従来の方法と比較して、ＤＣモータ２０の逆転時にＦＥＴ１～６に流れる電流を小さく抑えることができる。これにより、従来のように大電流用のスイッチング素子ＦＥＴを使用する必要がなくなり、スイッチング素子ＦＥＴの小型化、さらにコスト低減を図ることができる。
　また、回転方向の切替えを行わない場合には操作スイッチ１８のオン操作に追従してスイッチング素子ＦＥＴ１～６が動作し、ＤＣモータ２０が再起動するようになる。これにより、電動工具１０の応答性を保持することができる。 <Advantages of the electric power tool 10 according to the present embodiment>
According to the electric tool 10 according to the present embodiment, the DC motor 20 cannot be operated in the reverse direction unless the DC motor 20 is stopped. That is, when the electromotive force of the DC motor 20 becomes almost zero, the FETs 1 to 6 operate and a power supply voltage is applied to the DC motor 20.
For this reason, compared to the conventional method of applying a power supply voltage having a reverse polarity while the electromotive force of the DC motor 20 is large, the current flowing through the FETs 1 to 6 during the reverse rotation of the DC motor 20 can be suppressed. As a result, it is not necessary to use a switching element FET for large current as in the prior art, and the switching element FET can be reduced in size and cost can be reduced.
Further, when the rotation direction is not switched, the switching elements FET1 to FET6 operate following the ON operation of the operation switch 18, and the DC motor 20 is restarted. Thereby, the responsiveness of the electric tool 10 can be maintained.
＜変更例＞
　ここで、本発明は上記実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲における変更が可能である。例えば、本実施形態では、ＤＣモータ２０の回転方向を切替える場合には、ＤＣモータ２０が停止後でなければ再起動できないように構成する例を示した。しかし、ＤＣモータ２０の回転数が、例えば、操作スイッチのオン時の回転数の５０パーセント以下、あるいは２５パーセント以下、あるいは１０パーセント以下まで低下した後に、ＤＣモータ２０を逆転方向に再起動させられるように構成することも可能である。
　また、本実施形態では、ＤＣブラシレスモータ２０を使用する電動工具１０を例示したが、ブラシ付ＤＣモータを使用する電動工具に本発明を適用することも可能である。
　また、ＤＣモータ２０の回転方向を切替える場合、ＤＣモータ２０が停止後、あるいは回転数が所定値以下になった後、再起動させる例を示したが、操作スイッチ１８をオフした後、一定時間後に再起動可能にする構成でも可能である。 <Example of change>
Here, the present invention is not limited to the above-described embodiment, and can be modified without departing from the gist of the present invention. For example, in the present embodiment, when the rotation direction of the DC motor 20 is switched, an example in which the DC motor 20 can be restarted only after it has stopped has been shown. However, after the rotational speed of the DC motor 20 is reduced to, for example, 50% or less, 25% or less, or 10% or less of the rotational speed when the operation switch is turned on, the DC motor 20 can be restarted in the reverse direction. It is also possible to configure as described above.
In the present embodiment, the electric tool 10 using the DC brushless motor 20 is illustrated, but the present invention can also be applied to an electric tool using a brushed DC motor.
Also, in the case where the rotation direction of the DC motor 20 is switched, an example in which the DC motor 20 is restarted after the DC motor 20 stops or after the rotation speed becomes a predetermined value or less has been shown. A configuration in which restarting is possible later is also possible.
１０・・・・電動工具
１８・・・・操作スイッチ
１９・・・・切替えスイッチ
２０・・・・ＤＣモータ
４４・・・・スイッチング素子（ＦＥＴ１～６）
４６・・・・制御回路
                                                                                 10 .... Electric tool 18 .... Operating switch 19 .... Switch 20 ...... DC motor 44 ... Switching elements (FETs 1 to 6)
46... Control circuit

Claims (4)

  1. ＤＣモータを駆動させる複数のスイッチング素子と、入力信号に基づいてそれらのスイッチング素子を動作させる制御回路と、前記ＤＣモータの回転方向を切替える信号を前記制御回路に入力する切替えスイッチと、前記ＤＣモータを起動させる信号を前記制御回路に入力するトリガ形式の操作スイッチとを備える電動工具であって、
    　前記操作スイッチのオフ後、前記ＤＣモータが慣性力で回転しているときに、前記切替えスイッチにより回転方向が切替えられ、前記操作スイッチが再度オンしたときには、前記ＤＣモータの回転数が前記操作スイッチのオン時の回転数の５０パーセント以下まで低下した後に、前記制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させる構成であることを特徴とする電動工具。     A plurality of switching elements for driving the DC motor; a control circuit for operating the switching elements based on an input signal; a changeover switch for inputting a signal for switching the rotation direction of the DC motor to the control circuit; and the DC motor A trigger-type operation switch that inputs a signal to activate the control circuit to the control circuit,
    After the operation switch is turned off, the rotation direction is switched by the changeover switch when the DC motor is rotating with inertial force, and when the operation switch is turned on again, the rotation speed of the DC motor is changed to the operation switch. An electric tool characterized in that the control circuit operates the switching element on the basis of an ON signal of the operation switch after the rotational speed is reduced to 50% or less of the on-state rotation speed.
  2. 請求項１に記載の電動工具であって、
    　前記操作スイッチのオフ後、前記ＤＣモータが慣性力で回転しているときに、前記切替えスイッチが操作されないときは、前記制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させる構成であることを特徴とする電動工具。     The electric tool according to claim 1,
    A configuration in which the control circuit operates the switching element based on an ON signal of the operation switch when the switch is not operated when the DC motor rotates with inertial force after the operation switch is turned off. The electric tool characterized by being.
  3. 請求項１又は請求項２のいずれかに記載の電動工具であって、
    　前記操作スイッチのオフ後、前記ＤＣモータが慣性力で回転しているときに、前記切替えスイッチにより回転方向が切替えられ、前記操作スイッチが再度オンしたときには、前記ＤＣモータの回転が停止した後に、前記制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させる構成であることを特徴と電動工具。     The electric tool according to claim 1 or 2,
    After the operation switch is turned off, when the DC motor is rotated by inertia force, the rotation direction is switched by the changeover switch, and when the operation switch is turned on again, after the rotation of the DC motor is stopped, The power tool, wherein the control circuit is configured to operate the switching element based on an ON signal of the operation switch.
  4. ＤＣモータを駆動させる複数のスイッチング素子と、入力信号に基づいてそれらのスイッチング素子を動作させる制御回路と、前記ＤＣモータの回転方向を切替える信号を前記制御回路に入力する切替えスイッチと、前記ＤＣモータを起動させる信号を前記制御回路に入力するトリガ形式の操作スイッチとを備える電動工具であって、
    　前記操作スイッチのオフ後、前記ＤＣモータが慣性力で回転しているときに、前記切替えスイッチにより回転方向が切替えられ、前記操作スイッチが再度オンしたときには、前記操作スイッチがオフした時から所定時間後に、前記制御回路が前記操作スイッチのオン信号に基づいて前記スイッチング素子を動作させる構成であることを特徴とする電動工具。
                                                                                         A plurality of switching elements for driving the DC motor; a control circuit for operating the switching elements based on an input signal; a changeover switch for inputting a signal for switching the rotation direction of the DC motor to the control circuit; and the DC motor A trigger-type operation switch that inputs a signal to activate the control circuit to the control circuit,
    After the operation switch is turned off, when the DC motor is rotating with inertial force, the rotation direction is switched by the changeover switch, and when the operation switch is turned on again, the operation switch is turned off for a predetermined time. An electric tool characterized in that the control circuit is configured to operate the switching element based on an ON signal of the operation switch.
PCT/JP2009/066085 2009-01-29 2009-09-15 Electric tool WO2010087054A1 (en)

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JP2017135950A (en) * 2016-01-29 2017-08-03 株式会社マキタ Electric work machine
WO2017208709A1 (en) * 2016-05-31 2017-12-07 日立工機株式会社 Electric power tool

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000117649A (en) * 1998-10-08 2000-04-25 Maeda Metal Industries Ltd Forward and reverse rotation switching device of motor- driven fastening tool
JP2002305897A (en) * 2001-03-30 2002-10-18 Matsushita Electric Works Ltd Control circuit for electric elevator

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000117649A (en) * 1998-10-08 2000-04-25 Maeda Metal Industries Ltd Forward and reverse rotation switching device of motor- driven fastening tool
JP2002305897A (en) * 2001-03-30 2002-10-18 Matsushita Electric Works Ltd Control circuit for electric elevator

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