JP2021066003A

JP2021066003A - Power tools

Info

Publication number: JP2021066003A
Application number: JP2019195444A
Authority: JP
Inventors: 翔太渡邊; Shota Watanabe; 隼人榊原; Hayato Sakakibara
Original assignee: Nitto Kohki Co Ltd
Current assignee: Nitto Kohki Co Ltd
Priority date: 2019-10-28
Filing date: 2019-10-28
Publication date: 2021-04-30
Anticipated expiration: 2039-10-28
Also published as: JP7291602B2

Abstract

【課題】分解することなくクラッチ機構の摩耗状態を監視できるようにした動力工具を提供する。【解決手段】電動ドライバ１は、電動モータ１２の回転駆動軸１８に連結された遊星歯車機構２０と、ドライバビットが取り付けられる出力軸１６との間にクラッチ機構２２が配置されている。クラッチ機構２２に所定の最大トルク以上の負荷が作用すると、円柱状係合部材６０によって球状係合部材６８が変位部材７０とともに回転軸線Ｒの方向で変位される。これにより円柱状係合部材６０と球状係合部材６８との回転方向での係合が解除されて、回転トルクの伝達が解除される。回転トルクの伝達が解除されるときにセンサピン８０がブレーキ用光電センサ２６の投光部と受光部２６ａとの間に進入してブレーキ用光電センサ２６の出力値が上昇する。演算部３０は、このときの出力値に基づいてクラッチ機構２２の摩耗状態を判定する。【選択図】図３PROBLEM TO BE SOLVED: To provide a power tool capable of monitoring a wear state of a clutch mechanism without disassembling. SOLUTION: In an electric driver 1, a clutch mechanism 22 is arranged between a planetary gear mechanism 20 connected to a rotary drive shaft 18 of an electric motor 12 and an output shaft 16 to which a driver bit is attached. When a load of a predetermined maximum torque or more acts on the clutch mechanism 22, the cylindrical engaging member 60 displaces the spherical engaging member 68 together with the displacement member 70 in the direction of the rotation axis R. As a result, the engagement between the columnar engaging member 60 and the spherical engaging member 68 in the rotational direction is released, and the transmission of the rotational torque is released. When the transmission of the rotational torque is released, the sensor pin 80 enters between the light emitting portion and the light receiving portion 26a of the brake photoelectric sensor 26, and the output value of the brake photoelectric sensor 26 increases. The calculation unit 30 determines the wear state of the clutch mechanism 22 based on the output value at this time. [Selection diagram] Fig. 3

Description

本発明は、クラッチ機構を備える動力工具に関する。 The present invention relates to a power tool including a clutch mechanism.

電動モータを駆動部とする電動ドライバやエアモータを駆動部とするエアドリルなどの動力工具において、駆動部の回転駆動軸とドライバビットやドリルビットなどの加工工具が取り付けられる出力軸との間にクラッチ機構を設けて、駆動部から出力軸に加わる最大の回転トルクを制限するようにしたものがある（特許文献１、２）。例えば電動ドライバにクラッチ機構を設けることにより、ドライバビットを介してネジに加わる回転トルクを制限してネジが破損することを防止できる。また、ネジが着座して急激に回転トルクが大きくなることによりクラッチ機構が駆動連結を解除したときに、ねじ締めが完了したと判断してモータの駆動を停止させたりねじ締め本数をカウントしたりするようにすることもできる。 In a power tool such as an electric driver whose drive unit is an electric motor or an air drill whose drive unit is an air motor, a clutch mechanism is provided between the rotary drive shaft of the drive unit and the output shaft to which a machining tool such as a driver bit or a drill bit is attached. Is provided to limit the maximum rotational torque applied to the output shaft from the drive unit (Patent Documents 1 and 2). For example, by providing the electric driver with a clutch mechanism, it is possible to limit the rotational torque applied to the screw via the driver bit and prevent the screw from being damaged. In addition, when the clutch mechanism releases the drive connection due to the screw seating and the rotational torque suddenly increases, it is judged that the screw tightening is completed and the motor drive is stopped or the number of screw tightening is counted. You can also do it.

例えば上述の電動ドライバに設けられたクラッチ機構は、出力軸側に配置したクラッチボールが回転駆動軸側のクラッチ部材に回転方向で係合するように配置され、クラッチボールをスプリングによってクラッチ部材の側に付勢してクラッチボールがクラッチ部材に係合する状態を維持するようになっている。クラッチボールがクラッチ部材に回転方向で係合している間は回転駆動軸から出力軸に回転トルクが伝達され、過大な回転トルクが作用するとクラッチボールがスプリングの付勢力に抗して回転軸線の方向に変位してクラッチボールとクラッチ部材との回転方向での係合が解除され、回転トルクの伝達が解除されるようになっている。また、クラッチボールが回転軸線の方向で変位したことをセンサで検知することによりクラッチ機構が解除されたことを検出して、モータの駆動を停止させるなどの制御を行うようになっている。 For example, in the clutch mechanism provided in the electric driver described above, the clutch ball arranged on the output shaft side is arranged so as to engage with the clutch member on the rotation drive shaft side in the rotational direction, and the clutch ball is placed on the side of the clutch member by a spring. The clutch ball is urged to maintain the state of being engaged with the clutch member. While the clutch ball is engaged with the clutch member in the rotational direction, the rotational torque is transmitted from the rotational drive shaft to the output shaft, and when an excessive rotational torque acts, the clutch ball resists the urging force of the spring and becomes the rotational axis. By shifting in the direction, the engagement between the clutch ball and the clutch member in the rotational direction is released, and the transmission of the rotational torque is released. Further, by detecting that the clutch ball is displaced in the direction of the rotation axis with a sensor, it is detected that the clutch mechanism is released, and control such as stopping the driving of the motor is performed.

国際公開２０１７／０３８８４６号公報International Publication No. 2017/038846 特開２０１７−４２８７８号公報Japanese Unexamined Patent Publication No. 2017-42878

クラッチ機構は、上述のように各部品が機械的に接触しながら動作し、またクラッチ機構が解除される際には係合部材同士が強い力で擦れ合う。したがって、クラッチ機構は動作を続けるうちに各部品が摩耗していく。しかしながら、クラッチ機構を構成する部品の摩耗が進行していくと、一方の係合部材が他方の係合部材を乗り上げるときの回転軸線の方向での変位量が低下して、伝達される最大トルクが小さくなったりクラッチ機構が解除されたことを検知できなくなったりする虞がある。上述の動力工具においては、クラッチ機構の摩耗状態を確認するためには、動力工具を分解してクラッチ機構を構成する部品を直接確認する必要があるが、そのような作業は非常に煩雑である。 As described above, the clutch mechanism operates while the parts are in mechanical contact with each other, and when the clutch mechanism is released, the engaging members rub against each other with a strong force. Therefore, each part of the clutch mechanism wears as it continues to operate. However, as the wear of the parts constituting the clutch mechanism progresses, the amount of displacement in the direction of the rotation axis when one engaging member rides on the other engaging member decreases, and the maximum torque transmitted. May become smaller or it may not be possible to detect that the clutch mechanism has been disengaged. In the above-mentioned power tool, in order to check the wear state of the clutch mechanism, it is necessary to disassemble the power tool and directly check the parts constituting the clutch mechanism, but such work is very complicated. ..

そこで本発明は、動力工具を分解することなくクラッチ機構の摩耗状態を監視できるようにした動力工具を提供することを目的とする。 Therefore, an object of the present invention is to provide a power tool capable of monitoring a wear state of a clutch mechanism without disassembling the power tool.

すなわち本発明は、
回転駆動軸を有する駆動部と、
加工工具が取り付けられる工具取付部を有し、該駆動部の駆動に伴って回転軸線の周りで回転駆動される出力軸と、
該回転駆動軸と該出力軸とのうちの一方に駆動連結されて回転軸線の周りで回転される第１クラッチ係合部材、該回転駆動軸と該出力軸とのうちの他方に駆動連結されて該回転軸線の周りで回転される第２クラッチ係合部材、及び該第２クラッチ係合部材に当接した変位部材を有し、該第１クラッチ係合部材と該第２クラッチ係合部材とが回転方向で係合して該回転駆動軸から該出力軸に回転トルクを伝達し、所定の最大回転トルク以上の負荷が作用したときには第１クラッチ係合部材によって該第２クラッチ係合部材が該変位部材とともに回転軸線の方向で変位されて該第１クラッチ係合部材と該第２クラッチ係合部材との該回転方向での係合が解除されて該回転トルクの伝達が解除されるようにされた、クラッチ機構と、
該変位部材の該回転軸線の方向での位置を検出する位置センサと、
該クラッチ機構が該回転トルクの伝達を解除したときの該位置センサの出力値に基づいて、該クラッチ機構の摩耗状態を判定するようにされた演算部と、
を備える動力工具を提供する。 That is, the present invention
A drive unit with a rotary drive shaft and
An output shaft that has a tool mounting part to which a machining tool is mounted and is rotationally driven around a rotating axis as the driving part is driven.
A first clutch engaging member that is driven and connected to one of the rotation drive shaft and the output shaft and is rotated around the rotation axis, and is driven and connected to the other of the rotation drive shaft and the output shaft. It has a second clutch engaging member that is rotated around the rotation axis, and a displacement member that is in contact with the second clutch engaging member, and the first clutch engaging member and the second clutch engaging member. Is engaged in the rotational direction to transmit rotational torque from the rotational drive shaft to the output shaft, and when a load equal to or greater than a predetermined maximum rotational torque is applied, the first clutch engaging member causes the second clutch engaging member. Is displaced in the direction of the rotation axis together with the displacement member, the engagement between the first clutch engaging member and the second clutch engaging member in the rotation direction is released, and the transmission of the rotation torque is released. The clutch mechanism and
A position sensor that detects the position of the displacement member in the direction of the rotation axis, and
A calculation unit that determines the wear state of the clutch mechanism based on the output value of the position sensor when the clutch mechanism releases the transmission of the rotational torque.
Provide a power tool equipped with.

当該動力工具においては、クラッチ機構が回転トルクの伝達を解除したときの位置センサの出力値に基づいてクラッチ機構の摩耗状態を判定するようになっている。そのため、動力工具を分解することなくクラッチ機構の摩耗状態を監視することが可能となり、この判定結果に基づいて、クラッチ機構が解除される回転トルクの大きさを再調整したり、クラッチ機構の交換やメンテナンスの必要性を判断したりすることも可能となる。 In the power tool, the wear state of the clutch mechanism is determined based on the output value of the position sensor when the clutch mechanism releases the transmission of the rotational torque. Therefore, it is possible to monitor the wear state of the clutch mechanism without disassembling the power tool, and based on this determination result, readjust the magnitude of the rotational torque that releases the clutch mechanism or replace the clutch mechanism. It is also possible to judge the necessity of maintenance.

また、該演算部が、該クラッチ機構が該回転トルクの伝達を解除したときの該位置センサの出力値を所定の摩耗判定基準値と比較して、該出力値が該摩耗判定基準値にまで至らなかった場合にはエラー信号を発するようにすることもできる。 Further, the calculation unit compares the output value of the position sensor when the clutch mechanism releases the transmission of the rotational torque with a predetermined wear determination reference value, and the output value reaches the wear determination reference value. If it does not reach, an error signal can be issued.

このような構成により、エラー信号に基づいて駆動部の駆動を停止させたり、エラー表示部にエラーを表示したりするなどの対応を取ることが可能となる。 With such a configuration, it is possible to take measures such as stopping the driving of the driving unit or displaying an error on the error display unit based on the error signal.

具体的には、該位置センサの出力値が所定の解除判定基準値を超えて変化してから該解除判定基準値の範囲内に戻ったときに、該クラッチ機構が該回転トルクの伝達を解除したと判断して該駆動部の駆動を停止させるとともに、該位置センサの出力値が該解除判定基準値を超えてから該解除判定基準値内に戻るまでの間の該位置センサの出力値のうちで該解除判定基準値からの差が最も大きい出力値を記憶し、該駆動部の駆動が停止された後に該駆動部の駆動開始を指示する信号を受信したときに、記憶している出力値を該摩耗判定基準値と比較して、該記憶している出力値が該摩耗判定基準値にまで至っていなかった場合には該駆動部の駆動を開始せず、該記憶している出力値が該摩耗判定基準値にまで至っていた場合には該駆動部の駆動を開始するようにすることができる。 Specifically, when the output value of the position sensor changes beyond a predetermined release determination reference value and then returns to the range of the release determination reference value, the clutch mechanism releases the transmission of the rotational torque. The drive of the drive unit is stopped, and the output value of the position sensor during the period from when the output value of the position sensor exceeds the release determination reference value to when it returns to the release determination reference value. The output value that has the largest difference from the release determination reference value is stored, and when a signal instructing the start of driving of the driving unit is received after the driving of the driving unit is stopped, the stored output is stored. The value is compared with the wear determination reference value, and if the stored output value does not reach the wear determination reference value, the driving unit is not started and the stored output is not started. When the value reaches the wear determination reference value, the driving of the driving unit can be started.

また、該クラッチ機構が、該変位部材を介して該第２クラッチ係合部材を該回転軸線の方向で該第１クラッチ係合部材の側に付勢するクラッチスプリングをさらに有するようにすることができる。 Further, the clutch mechanism may further have a clutch spring for urging the second clutch engaging member toward the first clutch engaging member in the direction of the rotation axis via the displacement member. it can.

さらに、該位置センサが対向する投光部と受光部を有する光電センサであり、該第２クラッチ係合部材が変位したときに該変位部材の一部が該光電センサの該投光部と該受光部との間に進入して、該投光部から該受光部に向かって投光された光を部分的に遮るようにされ、該光電センサは該受光部で受光した光量に応じて出力値が変化するようにすることができる。 Further, the position sensor is a photoelectric sensor having a light emitting portion and a light receiving portion facing each other, and when the second clutch engaging member is displaced, a part of the displacement member is the light emitting portion of the photoelectric sensor and the light receiving portion. It enters between the light receiving unit and partially blocks the light projected from the light emitting unit toward the light receiving unit, and the photoelectric sensor outputs light according to the amount of light received by the light receiving unit. The value can be changed.

また、該クラッチ機構が、該回転駆動軸に駆動連結されて該回転軸線の周りで回転される第１クラッチプレートと、該第１クラッチプレートに対して該回転軸線の方向で対向して配置され、該出力軸に駆動連結されて該回転軸線の周りで該出力軸と共に回転する第２クラッチプレートと、を備え、該第１クラッチプレートが該第２クラッチプレートに対向する面に保持凹部を有し、該第２クラッチプレートが該回転軸線の方向で貫通した保持孔を有し、該第１クラッチ係合部材が該保持凹部に保持されて該第１クラッチプレートとともに回転するようにされ、該第２クラッチ係合部材が該保持孔内において該回転軸線の方向で変位可能に保持されて該第２クラッチプレートとともに回転するようにすることができる。 Further, the clutch mechanism is arranged so as to face the first clutch plate, which is driven and connected to the rotation drive shaft and rotates around the rotation axis, and faces the first clutch plate in the direction of the rotation axis. A second clutch plate that is driven and connected to the output shaft and rotates with the output shaft around the rotation axis is provided, and the first clutch plate has a holding recess on a surface facing the second clutch plate. The second clutch plate has a holding hole penetrating in the direction of the rotation axis, and the first clutch engaging member is held in the holding recess so as to rotate with the first clutch plate. The second clutch engaging member can be displaceably held in the holding hole in the direction of the rotation axis so as to rotate with the second clutch plate.

この場合には、該第１クラッチ係合部材が該回転軸線の放射方向に延びる円柱状係合部材であり、該第２クラッチ係合部材が球状係合部材であるようにすることができる。 In this case, the first clutch engaging member may be a columnar engaging member extending in the radial direction of the rotation axis, and the second clutch engaging member may be a spherical engaging member.

以下、本発明に係る動力工具の実施形態を添付図面に基づき説明する。 Hereinafter, embodiments of the power tool according to the present invention will be described with reference to the accompanying drawings.

本発明の一実施形態に係る電動ドライバの断面図である。It is sectional drawing of the electric driver which concerns on one Embodiment of this invention. 図１の電動ドライバの機能ブロック図である。It is a functional block diagram of the electric driver of FIG. 図１の電動ドライバのクラッチ機構の周囲の拡大図である。It is an enlarged view around the clutch mechanism of the electric driver of FIG. 出力軸の筒状軸部が押込まれた状態を示す、クラッチ機構の周囲の拡大図である。It is an enlarged view around the clutch mechanism which shows the state which the tubular shaft part of an output shaft is pushed. クラッチ機構を構成する部品の上方から見た分解斜視図である。It is an exploded perspective view seen from above of the component which constitutes a clutch mechanism. クラッチ機構を構成する部品の下方から見た分解斜視図である。It is an exploded perspective view seen from the bottom of the component constituting a clutch mechanism. クラッチ機構が回転トルクの伝達を解除した状態と示す、クラッチ機構の周囲の拡大図である。It is an enlarged view around the clutch mechanism which shows the state which the clutch mechanism has released the transmission of the rotational torque. 摩耗状態を判定する際の動作を示すフローチャートである。It is a flowchart which shows the operation at the time of determining the wear state. 内側保持孔に小径の球状係合部材を配置したときの、クラッチ機構の周囲の拡大図である。It is an enlarged view around the clutch mechanism when a small-diameter spherical engaging member is arranged in the inner holding hole. 図９のクラッチ機構においてクラッチが回転トルクの伝達を解除した状態を示す、クラッチ機構の周囲の拡大図である。It is an enlarged view around the clutch mechanism which shows the state which the clutch has released the transmission of the rotational torque in the clutch mechanism of FIG.

本発明の一実施形態に係る電動ドライバ（動力工具）１は、図１に示すように、工具ハウジング１０と、工具ハウジング１０内に配置された電動モータ（駆動部）１２と、ドライバビット（加工工具）が着脱可能に取り付けられる工具取付部１４を有する出力軸１６と、電動モータ１２の回転駆動軸１８の回転を減速して伝達する遊星歯車機構２０と、遊星歯車機構２０と出力軸１６との間に配置されたクラッチ機構２２とを備える。電動モータ１２の回転トルクは、遊星歯車機構２０及びクラッチ機構２２を介して出力軸１６に伝達される。工具ハウジング１０内にはさらに、電動モータ１２の駆動を開始させるためのスタート用光電センサ２４と、電動モータ１２の駆動を停止させるためのブレーキ用光電センサ（位置センサ）２６とが設けられており、後述するようにこれらの光電センサ２４、２６の出力値に基づいて電動モータ１２の駆動と停止を制御するようになっている。 As shown in FIG. 1, the electric driver (power tool) 1 according to the embodiment of the present invention includes a tool housing 10, an electric motor (drive unit) 12 arranged in the tool housing 10, and a driver bit (machining). An output shaft 16 having a tool mounting portion 14 to which a tool) can be detachably attached, a planetary gear mechanism 20 that decelerates and transmits the rotation of the rotation drive shaft 18 of the electric motor 12, a planetary gear mechanism 20, and an output shaft 16. It is provided with a clutch mechanism 22 arranged between the two. The rotational torque of the electric motor 12 is transmitted to the output shaft 16 via the planetary gear mechanism 20 and the clutch mechanism 22. Further, a start photoelectric sensor 24 for starting the drive of the electric motor 12 and a brake photoelectric sensor (position sensor) 26 for stopping the drive of the electric motor 12 are provided in the tool housing 10. As will be described later, the drive and stop of the electric motor 12 are controlled based on the output values of the photoelectric sensors 24 and 26.

工具ハウジング１０内に配置された制御回路２８には、図２に示すように、演算部３０と、電動モータ１２の駆動制御を行うためのモータ制御部３２と、制御プログラムや制御パラメータ等を記憶するためのメモリ３４が設けられている。スタート用光電センサ２４及びブレーキ用光電センサ２６は演算部３０に接続され、演算部３０がスタート用光電センサ２４及びブレーキ用光電センサ２６の出力値に基づいて、電動モータ１２の駆動の開始と停止を制御する。また、当該電動ドライバ１は、ＬＥＤの発光で何らかのエラーが生じたことを表示するように作業者から見やすい位置に配置されたエラー表示部３６も備える。なお、スタート用光電センサ２４は、互いに対向する投光部（図示しない）と受光部２４ａを有し、投光部から出射された光を受光部２４ａで受けて、受光部２４ａが受光した光量に応じた出力値を出力するようになっている。ブレーキ用光電センサ２６も同様に、互いに対向する投光部（図示しない）と受光部２６ａを有し、投光部から出射された光を受光部２６ａで受けて、受光部２６ａが受光した光量に応じた出力値を出力するようになっている。当該実施形態においては、スタート用光電センサ２４及びブレーキ用光電センサ２６は、受光部２４ａ、２６ａで受光する光量が低下するとそれに応じて出力値が上昇するように構成されている。 As shown in FIG. 2, the control circuit 28 arranged in the tool housing 10 stores a calculation unit 30, a motor control unit 32 for performing drive control of the electric motor 12, a control program, control parameters, and the like. A memory 34 is provided for this purpose. The start photoelectric sensor 24 and the brake photoelectric sensor 26 are connected to the calculation unit 30, and the calculation unit 30 starts and stops driving the electric motor 12 based on the output values of the start photoelectric sensor 24 and the brake photoelectric sensor 26. To control. The electric screwdriver 1 also includes an error display unit 36 arranged at a position that is easy for the operator to see so as to indicate that some error has occurred due to the light emission of the LED. The start photoelectric sensor 24 has a light projecting unit (not shown) and a light receiving unit 24a facing each other, and receives light emitted from the light emitting unit by the light receiving unit 24a, and the amount of light received by the light receiving unit 24a. The output value is output according to. Similarly, the photoelectric sensor 26 for a brake also has a light emitting unit (not shown) and a light receiving unit 26a facing each other, and the light emitted from the light emitting unit is received by the light receiving unit 26a, and the amount of light received by the light receiving unit 26a. The output value is output according to. In the embodiment, the start photoelectric sensor 24 and the brake photoelectric sensor 26 are configured so that the output value increases as the amount of light received by the light receiving units 24a and 26a decreases.

図３に示すように、出力軸１６は、クラッチ機構２２に連結された中実軸部３８と、中実軸部３８の外周面３８ａ上を摺動するように配置された筒状軸部４０とからなる。中実軸部３８と筒状軸部４０とは回転方向では固定されている。筒状軸部４０に形成された施錠子保持孔４２内には球状の施錠子４４が配置され、筒状軸部４０の外周面４０ａ上にはスリーブ４６が配置されている。スリーブ４６が図示の位置から先端側（図で見て下側）に変位すると施錠子４４が径方向外側に変位可能となる。この状態でドライバビットを筒状軸部４０の挿入孔４８内に挿入してスリーブ４６を元の位置に戻すと、ドライバビットが出力軸１６に固定される。このように、出力軸１６の工具取付部１４は、筒状軸部４０、施錠子４４、及びスリーブ４６によって構成されている。ドライバビットが工具取付部１４に取り付けられた状態で工具ハウジング１０を把持してドライバビットをネジに押し付けるように操作すると、図４に示すように、出力軸１６の筒状軸部４０が工具ハウジング１０内に押込まれる。筒状軸部４０が押込まれると、筒状軸部４０の後端部５０に配置されたスイッチプレート５２も筒状軸部４０を一緒に変位する。そうすると、スイッチプレート５２がスタート用光電センサ２４の投光部と受光部２４ａとの間に進入して、投光部から受光部２４ａに向かって投光された光を部分的に遮るようになる。スイッチプレート５２の進入量が大きくなるに従い受光部２４ａが受光する光量が小さくなり、そうするとスタート用光電センサの出力値は上昇していく。演算部３０は、所定のスタート閾値よりも大きい出力値（駆動開始を指示する信号）をスタート用光電センサ２４から受信したときに電動モータ１２の駆動を開始する。 As shown in FIG. 3, the output shaft 16 has a solid shaft portion 38 connected to the clutch mechanism 22 and a tubular shaft portion 40 arranged so as to slide on the outer peripheral surface 38a of the solid shaft portion 38. It consists of. The solid shaft portion 38 and the tubular shaft portion 40 are fixed in the rotational direction. A spherical locker 44 is arranged in the locker holding hole 42 formed in the tubular shaft portion 40, and a sleeve 46 is arranged on the outer peripheral surface 40a of the tubular shaft portion 40. When the sleeve 46 is displaced from the position shown in the drawing to the tip side (lower side when viewed in the drawing), the locker 44 can be displaced outward in the radial direction. In this state, when the driver bit is inserted into the insertion hole 48 of the tubular shaft portion 40 and the sleeve 46 is returned to the original position, the driver bit is fixed to the output shaft 16. As described above, the tool mounting portion 14 of the output shaft 16 is composed of the tubular shaft portion 40, the locker 44, and the sleeve 46. When the tool housing 10 is gripped and the driver bit is pressed against the screw while the driver bit is attached to the tool mounting portion 14, the tubular shaft portion 40 of the output shaft 16 becomes the tool housing as shown in FIG. It is pushed into 10. When the tubular shaft portion 40 is pushed in, the switch plate 52 arranged at the rear end portion 50 of the tubular shaft portion 40 also displaces the tubular shaft portion 40 together. Then, the switch plate 52 enters between the light emitting unit and the light receiving unit 24a of the start photoelectric sensor 24, and partially blocks the light projected from the light emitting unit toward the light receiving unit 24a. .. As the amount of penetration of the switch plate 52 increases, the amount of light received by the light receiving unit 24a decreases, and then the output value of the start photoelectric sensor increases. The calculation unit 30 starts driving the electric motor 12 when it receives an output value (a signal instructing drive start) larger than a predetermined start threshold value from the start photoelectric sensor 24.

クラッチ機構２２は、遊星歯車機構２０を介して電動モータ１２の回転駆動軸１８に駆動連結された第１クラッチプレート５４と、出力軸１６の中実軸部３８に固定して駆動連結された第２クラッチプレート５６とを備える。第１クラッチプレート５４と第２クラッチプレート５６とは、それぞれ回転軸線Ｒの周りで回転可能に配置されている。また第２クラッチプレート５６は第１クラッチプレート５４に対して対向するように配置されている。図５及び図６に示すように、第２クラッチプレート５６に対向する第１クラッチプレート５４の対向面５５には、径方向に延びる保持溝（保持凹部）５８が形成されており、保持溝５８内において回転軸線Ｒの放射方向に延びる円柱状係合部材（第１クラッチ係合部材）６０が回転可能に保持されるようになっている。第２クラッチプレート５６には、回転軸線Ｒの方向で貫通した２つの内側保持孔６２と、内側保持孔６２よりも径方向外側の位置で回転軸線Ｒの方向で貫通した２つの外側保持孔６４が形成されている。外側保持孔６４は、内側保持孔６２よりも大径となっている。内側保持孔６２には小径の球状係合部材（第２クラッチ係合部材）６６が保持されるようになっており、外側保持孔６４には小径の球状係合部材６６よりも大径とされた大径の球状係合部材（第２クラッチ係合部材）６８が保持されるようになっている。ただし、使用されるのは一方の係合部材だけであり、当該電動ドライバ１を組み立てる際に、内側保持孔６２に対応した小径の球状係合部材６６と外側保持孔６４に対応した大径の球状係合部材６８とのうちの一方の係合部材を選択して、選択された係合部材のみを対応した保持孔内に配置する。図１及び図３においては、外側保持孔６４に大径の球状係合部材６８が選択的に配置されている。図６に示すように、第１クラッチプレート５４の対向面５５には、内側保持孔６２内に小径の球状係合部材６６が配置されたときに小径の球状係合部材６６と係合する内側係合面５５ａと、外側保持孔６４内に大径の球状係合部材６８が配置されたときに大径の球状係合部材６８と係合する外側係合面５５ｂとが形成されている。内側係合面５５ａは、小径の球状係合部材６６と大径の球状係合部材６８との直径の差の分だけ、外側係合面５５ｂよりも第２クラッチプレート５６の側に突出している。これにより、内側保持孔６２内に小径の球状係合部材６６を配置したときに小径の球状係合部材６６が第２クラッチプレート５６から突出する高さと、外側保持孔６４内に大径の球状係合部材６８を配置したときに大径の球状係合部材６８が第２クラッチプレート５６から突出する高さとが同じになる。 The clutch mechanism 22 is driven and connected to the first clutch plate 54, which is drive-connected to the rotary drive shaft 18 of the electric motor 12 via the planetary gear mechanism 20, and the solid shaft portion 38, which is the output shaft 16. 2 Clutch plate 56 is provided. The first clutch plate 54 and the second clutch plate 56 are rotatably arranged around the rotation axis R, respectively. The second clutch plate 56 is arranged so as to face the first clutch plate 54. As shown in FIGS. 5 and 6, a holding groove (holding recess) 58 extending in the radial direction is formed on the facing surface 55 of the first clutch plate 54 facing the second clutch plate 56, and the holding groove 58 is formed. Inside, a columnar engaging member (first clutch engaging member) 60 extending in the radial direction of the rotation axis R is rotatably held. The second clutch plate 56 has two inner holding holes 62 penetrating in the direction of the rotation axis R and two outer holding holes 64 penetrating in the direction of the rotation axis R at positions radially outside the inner holding hole 62. Is formed. The outer holding hole 64 has a larger diameter than the inner holding hole 62. A small-diameter spherical engaging member (second clutch engaging member) 66 is held in the inner holding hole 62, and the outer holding hole 64 has a larger diameter than the small-diameter spherical engaging member 66. A large-diameter spherical engaging member (second clutch engaging member) 68 is held. However, only one engaging member is used, and when assembling the electric screwdriver 1, a small diameter spherical engaging member 66 corresponding to the inner holding hole 62 and a large diameter corresponding to the outer holding hole 64 are used. One of the spherical engaging members 68 is selected and only the selected engaging member is placed in the corresponding holding hole. In FIGS. 1 and 3, a large-diameter spherical engaging member 68 is selectively arranged in the outer holding hole 64. As shown in FIG. 6, the facing surface 55 of the first clutch plate 54 has an inner side that engages with the small-diameter spherical engaging member 66 when the small-diameter spherical engaging member 66 is arranged in the inner holding hole 62. An engaging surface 55a and an outer engaging surface 55b that engages with the large-diameter spherical engaging member 68 when the large-diameter spherical engaging member 68 is arranged in the outer holding hole 64 are formed. The inner engaging surface 55a protrudes toward the second clutch plate 56 from the outer engaging surface 55b by the difference in diameter between the small diameter spherical engaging member 66 and the large diameter spherical engaging member 68. .. As a result, the height at which the small-diameter spherical engaging member 66 protrudes from the second clutch plate 56 when the small-diameter spherical engaging member 66 is arranged in the inner holding hole 62, and the large-diameter spherical engaging member 66 in the outer holding hole 64. When the engaging member 68 is arranged, the height at which the large-diameter spherical engaging member 68 protrudes from the second clutch plate 56 is the same.

図３に示すように、クラッチ機構２２はさらに、第２クラッチプレート５６及び出力軸１６の中実軸部３８に対して回転軸線Ｒの方向で変位可能に配置された変位部材７０を備える。変位部材７０は、中実軸部３８の外周面３８ａ上を回転軸線Ｒの方向に摺動するスライド部材７２と、ベアリング７４によってスライド部材７２に対して回転可能とされたスラスト受け部材７６と、スプリング７８によってスラスト受け部材７６に押圧されてスライド部材７２及びスラスト受け部材７６と共に回転軸線Ｒの方向で変位するように配置されたセンサピン８０とを有する。変位部材７０のスラスト受け部材７６は、クラッチスプリング８２によって伝達ピン８４を介して第２クラッチプレート５６の側に押圧されている。大径の球状係合部材６８は、スライド部材７２の係合面７２ａに当接しているため、スラスト受け部材７６及びスライド部材７２を介して第１クラッチプレート５４及び円柱状係合部材６０の側に付勢されている。 As shown in FIG. 3, the clutch mechanism 22 further includes a displacement member 70 displaceable in the direction of the rotation axis R with respect to the solid shaft portion 38 of the second clutch plate 56 and the output shaft 16. The displacement member 70 includes a slide member 72 that slides on the outer peripheral surface 38a of the solid shaft portion 38 in the direction of the rotation axis R, and a thrust receiving member 76 that is made rotatable with respect to the slide member 72 by the bearing 74. It has a sensor pin 80 that is pressed by a thrust receiving member 76 by a spring 78 and is arranged so as to be displaced in the direction of the rotation axis R together with the slide member 72 and the thrust receiving member 76. The thrust receiving member 76 of the displacement member 70 is pressed toward the second clutch plate 56 by the clutch spring 82 via the transmission pin 84. Since the large-diameter spherical engaging member 68 is in contact with the engaging surface 72a of the slide member 72, the side of the first clutch plate 54 and the cylindrical engaging member 60 via the thrust receiving member 76 and the slide member 72. Is being urged to.

図４に示すように出力軸１６の筒状軸部４０が押込まれて電動モータ１２の駆動が開始されると、電動モータ１２の回転駆動軸１８に遊星歯車機構２０を介して駆動連結された第１クラッチプレート５４及び円柱状係合部材６０が回転軸線Ｒの周りで回転される。そうすると、円柱状係合部材６０が球状係合部材６８と回転方向で係合して、球状係合部材６８を介して回転トルクが第２クラッチプレート５６に伝達される。第２クラッチプレート５６は、出力軸１６の中実軸部３８に固定されているため、回転トルクは出力軸１６に伝達される。円柱状係合部材６０と球状係合部材６８は曲面で係合しており、回転トルクが伝達されている状態では、球状係合部材６８は円柱状係合部材６０から回転軸線Ｒの方向で円柱状係合部材６０から離れる向きに力を受ける。一方で、球状係合部材６８はクラッチスプリング８２によって第１クラッチプレート５４の側に付勢されている。そのため、円柱状係合部材６０から受ける力がクラッチスプリング８２の付勢力の範囲内である間は球状係合部材６８は回転軸線Ｒの方向に変位せず、円柱状係合部材６０と球状係合部材６８とが回転方向で係合して回転トルクが伝達される状態が維持される。 As shown in FIG. 4, when the tubular shaft portion 40 of the output shaft 16 is pushed in and the drive of the electric motor 12 is started, the drive is connected to the rotary drive shaft 18 of the electric motor 12 via the planetary gear mechanism 20. The first clutch plate 54 and the columnar engaging member 60 are rotated around the rotation axis R. Then, the columnar engaging member 60 engages with the spherical engaging member 68 in the rotational direction, and the rotational torque is transmitted to the second clutch plate 56 via the spherical engaging member 68. Since the second clutch plate 56 is fixed to the solid shaft portion 38 of the output shaft 16, the rotational torque is transmitted to the output shaft 16. The cylindrical engaging member 60 and the spherical engaging member 68 are engaged on a curved surface, and in a state where the rotational torque is transmitted, the spherical engaging member 68 is in the direction of the rotation axis R from the cylindrical engaging member 60. The force is applied in the direction away from the columnar engaging member 60. On the other hand, the spherical engaging member 68 is urged toward the first clutch plate 54 by the clutch spring 82. Therefore, while the force received from the columnar engaging member 60 is within the range of the urging force of the clutch spring 82, the spherical engaging member 68 does not displace in the direction of the rotation axis R, and the cylindrical engaging member 60 and the spherical engaging member 60 are engaged. A state in which the coupling member 68 is engaged in the rotational direction and the rotational torque is transmitted is maintained.

クラッチ機構２２に所定の最大回転トルク以上の負荷が作用すると、球状係合部材６８は円柱状係合部材６０によって回転軸線Ｒの方向に押されて、クラッチスプリング８２を圧縮しながら変位部材７０とともに第１クラッチプレート５４から離れる向き（図で見て下向き）に変位する。図７に示すように、球状係合部材６８が円柱状係合部材６０に完全に乗り上げた状態にまで変位すると、円柱状係合部材６０と球状係合部材６８との回転方向での係合が解除され、第１クラッチプレート５４から第２クラッチプレート５６への回転トルクの伝達も一時的に解除される。このとき、変位部材７０のセンサピン８０がブレーキ用光電センサ２６の投光部と受光部２６ａとの間に進入する。これにより、投光部から受光部２６ａに向かって投光された光をセンサピン８０が部分的に遮るようになる。当該実施形態においては、受光部２６ａで受光される光量が低下すると、その低下した光量に応じてブレーキ用光電センサ２６の出力値が上昇するようになっている。そのため、演算部３０は、ブレーキ用光電センサ２６の出力値に基づいて、投光部と受光部２６ａとの間におけるセンサピン８０の位置を検出することができる。演算部３０は、ブレーキ用光電センサ２６の出力値が所定の解除判定基準値を超えたときに、クラッチ機構２２が回転トルクの伝達を解除したと判断し、電動モータ１２の駆動を停止する。 When a load equal to or greater than a predetermined maximum rotational torque acts on the clutch mechanism 22, the spherical engaging member 68 is pushed in the direction of the rotation axis R by the cylindrical engaging member 60, and the clutch spring 82 is compressed together with the displacement member 70. It is displaced in a direction away from the first clutch plate 54 (downward as seen in the figure). As shown in FIG. 7, when the spherical engaging member 68 is displaced to a state where it completely rides on the cylindrical engaging member 60, the cylindrical engaging member 60 and the spherical engaging member 68 are engaged in the rotational direction. Is released, and the transmission of rotational torque from the first clutch plate 54 to the second clutch plate 56 is also temporarily released. At this time, the sensor pin 80 of the displacement member 70 enters between the light emitting portion and the light receiving portion 26a of the photoelectric sensor 26 for braking. As a result, the sensor pin 80 partially blocks the light projected from the light emitting unit toward the light receiving unit 26a. In the embodiment, when the amount of light received by the light receiving unit 26a decreases, the output value of the brake photoelectric sensor 26 increases according to the decreased amount of light. Therefore, the calculation unit 30 can detect the position of the sensor pin 80 between the light emitting unit and the light receiving unit 26a based on the output value of the brake photoelectric sensor 26. When the output value of the brake photoelectric sensor 26 exceeds a predetermined release determination reference value, the calculation unit 30 determines that the clutch mechanism 22 has released the transmission of the rotational torque, and stops driving the electric motor 12.

クラッチ機構２２において、特に円柱状係合部材６０と球状係合部材６８とは比較的に大きな力を受けながら擦れ合う。そのため、当該電動ドライバ１を繰り返し使用していくと、円柱状係合部材６０及び球状係合部材６８が徐々に摩耗していく。また、球状係合部材６８とスライド部材７２との間や、スライド部材７２とスラスト受け部材７６との間でも互いに擦れ合う動きが生じ得るため、これら部材も摩耗していく虞がある。このようにしてクラッチ機構２２を構成する部材が摩耗していくと、円柱状係合部材６０に球状係合部材６８が乗り上げてクラッチ機構２２による回転トルクの伝達が解除されたときにセンサピン８０がブレーキ用光電センサ２６の投光部と受光部２６ａとの間に進入する量が小さくなっていく。当該電動ドライバ１においては、演算部３０がブレーキ用光電センサ２６の出力値を監視しており、ブレーキ用光電センサ２６の出力値に基づいて投光部と受光部２６ａとの間でセンサピン８０の位置を検出して、クラッチ機構２２の摩耗状態を判定するようになっている。 In the clutch mechanism 22, the columnar engaging member 60 and the spherical engaging member 68 rub against each other while receiving a relatively large force. Therefore, as the electric screwdriver 1 is used repeatedly, the columnar engaging member 60 and the spherical engaging member 68 gradually wear. Further, since movements of rubbing against each other may occur between the spherical engaging member 68 and the slide member 72 and between the slide member 72 and the thrust receiving member 76, these members may also wear. When the members constituting the clutch mechanism 22 are worn in this way, the sensor pin 80 is released when the spherical engaging member 68 rides on the cylindrical engaging member 60 and the transmission of the rotational torque by the clutch mechanism 22 is released. The amount of entry between the light emitting portion and the light receiving portion 26a of the photoelectric sensor 26 for the brake becomes smaller. In the electric driver 1, the calculation unit 30 monitors the output value of the photoelectric photoelectric sensor 26 for the brake, and the sensor pin 80 is located between the light emitting unit and the light receiving unit 26a based on the output value of the photoelectric sensor 26 for the brake. The position is detected to determine the wear state of the clutch mechanism 22.

当該電動ドライバ１における摩耗状態の判定は、具体的には図８のフローチャートに示す動作により行われる。当該電動ドライバ１を電源に接続すると演算部３０が起動する（Ｓ１０）。演算部３０は、スタート用光電センサ２４の出力値を監視し、スタート用光電センサ２４の出力値が所定のスタート閾値よりも大きくなったら（Ｓ１２）、工具取付部１４に取り付けられたドライバビットが押し込まれたと判断して電動モータ１２の回転駆動を開始する（Ｓ１４）。次に演算部３０は、ブレーキ用光電センサ２６の出力値を監視して、ブレーキ用光電センサ２６の出力値が所定の解除判定基準値よりも大きくなり（Ｓ１６）その後に解除判定基準値以下の値に戻ったときに（Ｓ１７）、その間の出力値のうちの解除判定基準値からの差が最も大きい最大出力値をメモリ３４に記憶して（Ｓ１８）、電動モータ１２の駆動を停止させる（Ｓ２０）。演算部３０は、再びスタート用光電センサ２４の出力値を監視し、スタート用光電センサ２４の出力値がスタート閾値よりも大きい値にまで変化したら（Ｓ２２）、メモリ３４に記憶されているブレーキ用光電センサ２６の最大出力値を所定の摩耗判定基準値と比較する（Ｓ２４）。最大出力値が摩耗判定基準値にまで上昇して摩耗判定基準値以上となっていた場合には、センサピン８０は十分に大きく変位していてクラッチ機構２２はそれほど摩耗していないと判断して、電動モータ１２の駆動を再び開始する（Ｓ１４）。一方で、最大出力値が摩耗判定基準値にまで至っておらず、よって摩耗判定基準値よりも小さい場合には、センサピン８０が十分に変位しておらずクラッチ機構２２が摩耗していると判断して、エラー信号を発する（Ｓ２６）。エラー信号が発せられると、クラッチ機構２２の摩耗が一定以上進行していることを示すようにエラー表示部３６が発光する。またこの場合には電動モータ１２の駆動は開始されない。なお、スタート用光電センサ２４及びブレーキ用光電センサ２６は、受光部２６ａで受光する光量が低下したときに出力値が低下するようになっていてもよい。この場合には、スタート用光電センサ２４の出力値がスタート閾値よりも小さな値にまで変化したときに電動モータ１２の駆動が開始される。またブレーキ用光電センサ２６の出力値が、解除判定基準値よりも小さな値にまで変化してから解除判定基準値以上の値に戻ったときにクラッチ機構２２が解除されたと判断し、その間の出力値のうちの解除判定基準値からの差が最も大きい最小出力値が摩耗判定基準値以下にまで至らず摩耗判定基準値よりも大きい値であった場合にはエラー信号が発せられる。 The wear state of the electric screwdriver 1 is specifically determined by the operation shown in the flowchart of FIG. When the electric screwdriver 1 is connected to a power source, the calculation unit 30 is activated (S10). The calculation unit 30 monitors the output value of the start photoelectric sensor 24, and when the output value of the start photoelectric sensor 24 becomes larger than a predetermined start threshold value (S12), the driver bit attached to the tool attachment unit 14 is released. It is determined that the motor 12 has been pushed in, and the rotary drive of the electric motor 12 is started (S14). Next, the calculation unit 30 monitors the output value of the brake photoelectric sensor 26, and the output value of the brake photoelectric sensor 26 becomes larger than the predetermined release determination reference value (S16) and then equal to or less than the release determination reference value. When the value is returned (S17), the maximum output value having the largest difference from the release determination reference value among the output values during that period is stored in the memory 34 (S18), and the drive of the electric motor 12 is stopped (S17). S20). The calculation unit 30 monitors the output value of the start photoelectric sensor 24 again, and when the output value of the start photoelectric sensor 24 changes to a value larger than the start threshold value (S22), the brake is stored in the memory 34. The maximum output value of the photoelectric sensor 26 is compared with a predetermined wear determination reference value (S24). When the maximum output value rises to the wear judgment reference value and exceeds the wear judgment reference value, it is determined that the sensor pin 80 is sufficiently displaced and the clutch mechanism 22 is not worn so much. The drive of the electric motor 12 is restarted (S14). On the other hand, if the maximum output value has not reached the wear determination reference value and is therefore smaller than the wear determination reference value, it is determined that the sensor pin 80 is not sufficiently displaced and the clutch mechanism 22 is worn. Then, an error signal is issued (S26). When the error signal is issued, the error display unit 36 emits light so as to indicate that the wear of the clutch mechanism 22 has progressed by a certain amount or more. Further, in this case, the driving of the electric motor 12 is not started. The output value of the start photoelectric sensor 24 and the brake photoelectric sensor 26 may decrease when the amount of light received by the light receiving unit 26a decreases. In this case, the driving of the electric motor 12 is started when the output value of the start photoelectric sensor 24 changes to a value smaller than the start threshold value. Further, when the output value of the brake photoelectric sensor 26 changes to a value smaller than the release determination reference value and then returns to a value equal to or higher than the release determination reference value, it is determined that the clutch mechanism 22 has been released, and the output during that period. If the minimum output value having the largest difference from the release judgment reference value among the values does not reach the wear judgment reference value or less and is larger than the wear judgment reference value, an error signal is issued.

図９及び図１０に示すように、大径の球状係合部材６８に代えて、小径の球状係合部材６６を内側保持孔６２内に選択的に配置して組み立てることもできる。上述のように、内側保持孔６２内に配置された小径の球状係合部材６６は、第１クラッチプレート５４の対向面５５において、外側係合面５５ｂよりも突出した内側係合面５５ａと係合する。これにより、クラッチ機構２２が解除されていない図９の状態において、クラッチ機構２２の変位部材７０は、大径の球状係合部材６８を配置した図３の状態と同じ位置となる。よって、ブレーキ用光電センサ２６に対するセンサピン８０の位置も同じになる。一方で、クラッチ機構２２が解除された図１０の状態においては、大径の球状係合部材６８を配置した図７の状態よりも変位部材７０の変位量が小さい。よって、センサピン８０がブレーキ用光電センサ２６の投光部と受光部２６ａとの間に進入する量は、図７の場合よりも小さい。そのため、小径の球状係合部材６６を選択的に配置した場合には、解除判定基準値と摩耗判定基準値は大径の球状係合部材６８を選択的に配置したときに比べて、大きな値に設定される。 As shown in FIGS. 9 and 10, instead of the large-diameter spherical engaging member 68, a small-diameter spherical engaging member 66 can be selectively arranged and assembled in the inner holding hole 62. As described above, the small-diameter spherical engaging member 66 arranged in the inner holding hole 62 engages with the inner engaging surface 55a protruding from the outer engaging surface 55b on the facing surface 55 of the first clutch plate 54. It fits. As a result, in the state of FIG. 9 in which the clutch mechanism 22 is not released, the displacement member 70 of the clutch mechanism 22 is in the same position as in the state of FIG. 3 in which the large-diameter spherical engaging member 68 is arranged. Therefore, the position of the sensor pin 80 with respect to the brake photoelectric sensor 26 is also the same. On the other hand, in the state of FIG. 10 in which the clutch mechanism 22 is released, the displacement amount of the displacement member 70 is smaller than that in the state of FIG. 7 in which the large-diameter spherical engaging member 68 is arranged. Therefore, the amount of the sensor pin 80 entering between the light emitting portion and the light receiving portion 26a of the photoelectric sensor 26 for the brake is smaller than that in the case of FIG. Therefore, when the small diameter spherical engaging member 66 is selectively arranged, the release determination reference value and the wear determination reference value are larger than when the large diameter spherical engaging member 68 is selectively arranged. Is set to.

クラッチ機構２２が解除されるときの変位部材７０の変位量が小さい方がより小さい回転トルクでクラッチ機構２２が解除されることになる。また円柱状係合部材６０に対して球状係合部材６６、６８が係合する位置が、回転軸線Ｒに対してより径方向内側にある方がより小さい回転トルクでクラッチ機構２２が解除されることになる。したがって、小径の球状係合部材６６を内側保持孔６２に選択的に配置した場合には、大径の球状係合部材６８を外側保持孔６４に選択的に配置した場合に比べて、より小さな回転トルクでクラッチ機構２２が解除されることになる。すなわち、大径の球状係合部材６８を外側保持孔６４に配置するか、小径の球状係合部材６６を内側保持孔６２に配置するかで、クラッチ機構２２が伝達可能な最大回転トルクの大きさを変更することが可能となる。 The smaller the displacement amount of the displacement member 70 when the clutch mechanism 22 is released, the smaller the rotational torque is used to release the clutch mechanism 22. Further, the clutch mechanism 22 is released with a smaller rotational torque when the positions where the spherical engaging members 66 and 68 are engaged with the cylindrical engaging member 60 are inward in the radial direction with respect to the rotation axis R. It will be. Therefore, when the small-diameter spherical engaging member 66 is selectively arranged in the inner holding hole 62, it is smaller than when the large-diameter spherical engaging member 68 is selectively arranged in the outer holding hole 64. The clutch mechanism 22 is released by the rotational torque. That is, the maximum rotational torque that can be transmitted by the clutch mechanism 22 is large depending on whether the large-diameter spherical engaging member 68 is arranged in the outer holding hole 64 or the small-diameter spherical engaging member 66 is arranged in the inner holding hole 62. It is possible to change the torque.

当該電動ドライバ１においては、クラッチ機構２２が回転トルクの伝達を解除したときのブレーキ用光電センサ２６の出力値に基づいてクラッチ機構２２の摩耗状態を判定するようになっている。この判定結果に基づいて、クラッチスプリング８２の圧縮量を大きくしてクラッチ機構２２が解除される際の回転トルクの大きさを調整したり、クラッチ機構２２の交換やメンテナンスの必要性を判断したりすることが可能となる。なお、摩耗状態の判定は、摩耗が一定量を超えたか否かの２つの状態だけを示すのではなく、ブレーキ用光電センサ２６の出力値に基づいて摩耗の進行具合を３段階以上またはアナログ的に無段階で示すようにしてもよい。 In the electric driver 1, the wear state of the clutch mechanism 22 is determined based on the output value of the braking photoelectric sensor 26 when the clutch mechanism 22 releases the transmission of the rotational torque. Based on this determination result, the amount of compression of the clutch spring 82 is increased to adjust the magnitude of the rotational torque when the clutch mechanism 22 is released, and the necessity of replacement or maintenance of the clutch mechanism 22 is determined. It becomes possible to do. It should be noted that the determination of the wear state does not only indicate two states of whether or not the wear exceeds a certain amount, but also determines the progress of the wear in three or more stages or analog based on the output value of the photoelectric sensor 26 for the brake. It may be shown steplessly.

以上に本発明の実施形態について説明をしたが、本発明はこれら実施形態に限定されるものではない。例えば、第１クラッチ係合部材としての円柱状係合部材は、円柱形状ではなく例えば球状とするなど他の形状の部材としてもよいし、第１クラッチプレートと一体に形成して第１クラッチプレートから突出した突部としてもよい。第２クラッチ係合部材としての球状係合部材も同様に、他の形状としたり変位部材と一体に形成したりしてもよい。また、第１クラッチ部材を出力軸に駆動連結し、第２クラッチ係合部材を電動モータの回転駆動軸に駆動連結して、クラッチ機構が解除されるときに変位部材が回転駆動軸側に変位するように構成することもできる。さらには、変位部材の位置を検出するための位置センサとして、磁気センサやメカニカルスイッチなどの他の形態のセンサを使用することもできる。さらには、上記実施形態においては本発明にかかる動力工具を、電動モータを駆動部とする電動ドライバを例として説明をしているが、例えば電動ドリルや電動研磨機などの電動ドライバ以外の電動工具とすることもできるし、エアモータを駆動部とするエアー工具のような他の動力工具とすることもできる。 Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the columnar engaging member as the first clutch engaging member may be a member having another shape such as a spherical shape instead of a cylindrical shape, or may be integrally formed with the first clutch plate to form a first clutch plate. It may be a protrusion protruding from the surface. Similarly, the spherical engaging member as the second clutch engaging member may have another shape or may be integrally formed with the displacement member. Further, the first clutch member is driven and connected to the output shaft, the second clutch engaging member is driven and connected to the rotary drive shaft of the electric motor, and the displacement member is displaced to the rotary drive shaft side when the clutch mechanism is released. It can also be configured to do so. Further, as a position sensor for detecting the position of the displacement member, a sensor of another form such as a magnetic sensor or a mechanical switch can be used. Further, in the above embodiment, the power tool according to the present invention is described by taking an electric screwdriver having an electric motor as a drive unit as an example, but for example, an electric tool other than the electric screwdriver such as an electric drill or an electric grinding machine. It can also be used as another power tool such as an air tool whose drive unit is an air motor.

１電動ドライバ（動力工具）
１０工具ハウジング
１２電動モータ（駆動部）
１４工具取付部
１６出力軸
１８回転駆動軸
２０遊星歯車機構
２２クラッチ機構
２４スタート用光電センサ
２４ａ受光部
２６ブレーキ用光電センサ（位置センサ）
２６ａ受光部
２８制御回路
３０演算部
３２モータ制御部
３４メモリ
３６エラー表示部
３８中実軸部
３８ａ外周面
４０筒状軸部
４０ａ外周面
４２施錠子保持孔
４４施錠子
４６スリーブ
４８挿入孔
５０後端部
５２スイッチプレート
５４第１クラッチプレート
５５対向面
５５ａ内側係合面
５５ｂ外側係合面
５６第２クラッチプレート
５８保持溝（保持凹部）
６０円柱状係合部材（第１クラッチ係合部材）
６２内側保持孔
６４外側保持孔
６６小径の球状係合部材（第２クラッチ係合部材）
６８大径の球状係合部材（第２クラッチ係合部材）
７０変位部材
７２スライド部材
７２ａ係合面
７４ベアリング
７６スラスト受け部材
７８スプリング
８０センサピン
８２クラッチスプリング
８４伝達ピン
Ｒ回転軸線 1 Electric screwdriver (power tool)
10 Tool housing 12 Electric motor (drive unit)
14 Tool mounting part 16 Output shaft 18 Rotational drive shaft 20 Planetary gear mechanism 22 Clutch mechanism 24 Start photoelectric sensor 24a Light receiving part 26 Brake photoelectric sensor (position sensor)
26a Light receiving unit 28 Control circuit 30 Calculation unit 32 Motor control unit 34 Memory 36 Error display unit 38 Solid shaft part 38a Outer peripheral surface 40 Cylindrical shaft part 40a Outer peripheral surface 42 Locker holding hole 44 Locker 46 Sleeve 48 Insertion hole 50 After End 52 Switch plate 54 First clutch plate 55 Facing surface 55a Inner engaging surface 55b Outer engaging surface 56 Second clutch plate 58 Holding groove (holding recess)
60 Cylindrical engaging member (first clutch engaging member)
62 Inner holding hole 64 Outer holding hole 66 Small diameter spherical engaging member (second clutch engaging member)
68 Large diameter spherical engaging member (second clutch engaging member)
70 Displacement member 72 Slide member 72a Engagement surface 74 Bearing 76 Thrust receiving member 78 Spring 80 Sensor pin 82 Clutch spring 84 Transmission pin R Rotation axis

Claims

A drive unit with a rotary drive shaft and
An output shaft that has a tool mounting part to which a machining tool is mounted and is rotationally driven around a rotating axis as the driving part is driven.
A first clutch engaging member that is driven and connected to one of the rotation drive shaft and the output shaft and is rotated around the rotation axis, and is driven and connected to the other of the rotation drive shaft and the output shaft. It has a second clutch engaging member that is rotated around the rotation axis, and a displacement member that is in contact with the second clutch engaging member, and the first clutch engaging member and the second clutch engaging member. Is engaged in the rotational direction to transmit rotational torque from the rotational drive shaft to the output shaft, and when a load equal to or greater than a predetermined maximum rotational torque is applied, the first clutch engaging member causes the second clutch engaging member. Is displaced in the direction of the rotation axis together with the displacement member, the engagement between the first clutch engaging member and the second clutch engaging member in the rotation direction is released, and the transmission of the rotation torque is released. The clutch mechanism and
A position sensor that detects the position of the displacement member in the direction of the rotation axis, and
A calculation unit that determines the wear state of the clutch mechanism based on the output value of the position sensor when the clutch mechanism releases the transmission of the rotational torque.
Power tools equipped with.

The calculation unit compares the output value of the position sensor when the clutch mechanism releases the transmission of the rotational torque with a predetermined wear determination reference value, and the output value does not reach the wear determination reference value. The power tool according to claim 1, wherein an error signal is emitted in the case of the case.

When the calculation unit returns to the range of the release determination reference value after the output value of the position sensor changes beyond a predetermined release determination reference value, the clutch mechanism releases the transmission of the rotational torque. The drive of the drive unit is stopped, and the output value of the position sensor during the period from when the output value of the position sensor exceeds the release determination reference value to when it returns to the release determination reference value. The output value that has the largest difference from the release determination reference value is stored, and when a signal instructing the start of driving of the driving unit is received after the driving of the driving unit is stopped, the stored output is stored. The value is compared with the wear determination reference value, and if the stored output value does not reach the wear determination reference value, the driving unit is not started and the stored output is not started. The power tool according to claim 2, wherein the drive of the drive unit is started when the value reaches the wear determination reference value.

The clutch mechanism further includes a clutch spring that urges the second clutch engaging member toward the first clutch engaging member in the direction of the rotation axis via the displacement member, according to claims 1 to 3. The power tool according to any one item.

The position sensor is a photoelectric sensor having a light emitting portion and a light receiving portion facing each other, and when the second clutch engaging member is displaced, a part of the displacement member is the light emitting portion and the light receiving portion of the photoelectric sensor. The light is partially blocked from the light projecting unit toward the light receiving unit, and the photoelectric sensor has an output value according to the amount of light received by the light receiving unit. The power tool according to any one of claims 1 to 4, which is adapted to be changed.

The clutch mechanism is arranged so as to face the first clutch plate, which is driven and connected to the rotation drive shaft and is rotated around the rotation axis, and the first clutch plate in the direction of the rotation axis. It comprises a second clutch plate that is drive-coupled to the output shaft and rotates with the output shaft around the rotation axis, and the first clutch plate has a holding recess on a surface facing the second clutch plate. The second clutch plate has a holding hole penetrating in the direction of the rotation axis, and the first clutch engaging member is held in the holding recess so as to rotate with the first clutch plate. The power tool according to any one of claims 1 to 5, wherein the clutch engaging member is displaceably held in the holding hole in the direction of the rotation axis so as to rotate together with the second clutch plate. ..

The power tool according to claim 6, wherein the first clutch engaging member is a columnar engaging member extending in the radial direction of the rotation axis, and the second clutch engaging member is a spherical engaging member.