JP2012171049A - Electric power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power tool capable of suppressing impact of engagement when a reduction gear ratio is changed and capable of rapidly and smoothly completing reduction gear ratio change.SOLUTION: The electric power tool includes a motor 1, a reduction gear mechanism part 2 and a reduction gear ratio switching means switching the reduction gear ratio of the reduction gear mechanism part 2. The reduction gear mechanism part 2 is formed by using a switching member 7 which is freely slidable in an axial direction and a gear member 5 which can be engaged with the switching member 7. The reduction gear ratio switching means has a reduction-gear actuator 6 sliding the switching member 7, a load sensing part sensing an operation load state of the reduction-gear actuator 6 and a control part controlling the motor 1 and the reduction-gear actuator 6. The control part starts the reduction-gear actuator 6 and reduces relative rotary speed of the switching member 7 and the gear member 5 according to the sensing result of the load sensing part.

Description

  The present invention relates to an electric tool provided with a changeable reduction ratio.

  In a power tool provided with a speed reduction mechanism section, there is a structure for switching the engagement state by sliding a switching member such as a ring gear constituting the planetary speed reduction mechanism in the axial direction as a structure for switching the speed reduction ratio of the speed reduction mechanism section. .

  For example, in the electric tools described in Patent Document 1 and Patent Document 2, the sliding operation of the switching member made of a ring gear is automatically performed using a solenoid. In this conventional electric tool, in order to suppress the impact when the switching member engages with another gear member, the rotation of the motor is stopped or reduced when the solenoid is started.

  In the above-described conventional power tool, when a change occurs in the current of the motor serving as the drive source, the control unit that detects this changes the start of the solenoid and the rotation stop of the motor according to the set timing. Is running. Specifically, first, the rotation of the motor for suppressing the impact is reliably stopped, and then the solenoid is activated to take measures to suppress the impact at the time of engagement as much as possible.

JP 2009-56590 A JP 2009-78349 A

  By the way, there is a certain amount of time between the timing at which the switching member is actually engaged with the predetermined gear member and the timing at which the motor is decelerated and the motor actually stops rotating as intended. There is variation. In the conventional electric tool described above, since the solenoid is started after the motor rotation is reliably stopped, it is difficult to complete the reduction ratio change in a short time.

  That is, the conventional electric tool as described above is insufficient to suppress the impact of engagement when changing the reduction ratio and to complete the reduction ratio change smoothly in a short time. Met.

  It is an object of the present invention to provide an electric tool that can suppress the impact of engagement when changing the reduction ratio and that can complete the reduction ratio change quickly and smoothly.

  In order to solve the above-described problems, the power tool of the present invention has the following configuration.

  An electric power tool of the present invention includes an electric motor including a motor as a drive source, a reduction mechanism that transmits the rotational power of the motor after decelerating, and a reduction ratio switching unit that switches a reduction ratio of the reduction mechanism. It is a tool.

  The speed reduction mechanism unit uses a switching member that is slidable in the axial direction, and a gear member that is switched between an engagement state and a non-engagement state with the switching member in accordance with an axial slide position of the switching member. Thus, the reduction ratio is formed to be switched.

  The reduction ratio switching means includes a shift actuator that slides the switching member in the axial direction, a load detection unit that detects an operation load state of the shift actuator, and activates the shift actuator and And a controller that reduces a relative rotational speed of the switching member and the gear member according to a detection result.

  It is preferable that the control unit further changes drive control of the shift actuator according to a detection result of the load detection unit.

  It is preferable that the reduction ratio switching unit further includes a slide position detection unit that detects a slide position of the switching member.

  At this time, the control unit detects the detection result of the load detection unit and the detection of the slide position detection unit when the switching member is not slid to a predetermined target position when the shift actuator is driven. When judged by the result, it is preferable that the sliding direction of the switching member by the speed change actuator is once reversed.

  In addition, when the control unit drives the shift actuator, if the switching member is not slid to a predetermined target position, a detection result of the load detection unit and a detection result of the slide position detection unit It is also preferable to change the slide driving force of the switching member by the shift actuator.

  In addition, when the control unit drives the shift actuator, if the switching member is not slid to a predetermined target position, a detection result of the load detection unit and a detection result of the slide position detection unit Is determined, the relative rotation position of the switching member and the gear member is preferably changed while maintaining the sliding drive of the switching member by the speed change actuator.

  In addition, when the control unit drives the shift actuator, if the switching member is not slid to a predetermined target position, a detection result of the load detection unit and a detection result of the slide position detection unit Is determined, the relative rotation position of the switching member and the gear member is preferably changed in a state in which the sliding drive of the switching member by the shifting actuator is stopped.

  At this time, it is preferable that the controller is configured to increase the rotational power and change the relative rotational position when it is determined that the rotational power is reduced or stopped.

  Furthermore, the control unit increases the rotational acceleration that increases the rotational power when the switching member is sliding compared to when the switching member is not sliding. Is preferred.

  The present invention has an effect that it is possible to suppress the impact of engagement when changing the reduction ratio, and to complete the change of the reduction ratio quickly and smoothly.

It is principal part explanatory drawing of the electric tool of Embodiment 1 of this invention. It is a sectional side view of an electric tool same as the above. It is an internal side view of an electric tool same as the above. It is a back sectional view of an electric tool same as the above. It is a disassembled perspective view of the deceleration mechanism part of an electric tool same as the above. The state of the 1st speed of the deceleration mechanism part same as the above is shown, (a) is a side sectional view, and (b) is a side view. It is a sectional side view which shows the state in the middle of switching of 1st speed and 2nd speed of the deceleration mechanism part same as the above. The 2nd speed state of the deceleration mechanism part same as the above is shown, (a) is a sectional side view, (b) is a side view. It is a sectional side view which shows the state in the middle of the 2nd speed and 3rd speed switching of the deceleration mechanism part same as the above. The state of the 3rd speed of the deceleration mechanism part same as the above is shown, (a) is a side sectional view, and (b) is a side view. It is principal part explanatory drawing of the electric tool of Embodiment 5 of this invention, (a) is the state of 2nd speed, (b) is the state in the middle of switching between 2nd speed and 3rd speed, (c) is in the state of 3rd speed. is there. It is principal part explanatory drawing of the electric tool of Embodiment 6 of this invention. It is principal part explanatory drawing of the electric tool of Embodiment 7 of this invention, (a) is the state of 2nd speed, (b) is the state in the middle of switching between 2nd speed and 3rd speed, (c) is in the state of 3rd speed. is there. It is principal part explanatory drawing of the electric tool of Embodiment 8 of this invention, (a) is the state of 2nd speed, (b) is the state in the middle of switching between 2nd speed and 3rd speed, (c) is in the state of 3rd speed. is there.

  The present invention will be described based on embodiments shown in the accompanying drawings.

<Embodiment 1>
2 to 4 show a first embodiment of the power tool of the present invention. The electric tool of the present embodiment includes a motor (main motor) 1 that is a drive source, a speed reduction mechanism portion 2 that transmits the rotational power of the motor 1 after being decelerated, and a rotation that is transmitted via the speed reduction mechanism portion 2. A drive transmission unit 3 that transmits power to the output shaft 4 is accommodated in the body housing 101. A gripping part housing 102 extends from the body housing 101, and a trigger switch 103 is provided in the gripping part housing 102 so as to be retractable. A main body housing 100 of the electric power tool includes a body housing 101 and a gripping part housing 102.

  The body housing 101 accommodates the speed change actuator 6 so that the axial direction thereof is parallel to the motor 1 and the speed reduction mechanism section 2. The speed change actuator 6 is a rotary actuator, and the switching member 7 of the speed reduction mechanism 2 is slid through the speed change cam plate 8 to switch the speed reduction ratio. This will be described in detail later.

  5 to 10 show the structure of the speed reduction mechanism unit 2 and the like in more detail. The speed reduction mechanism unit 2 of the present embodiment accommodates a three-stage planetary speed reduction mechanism in the gear case 9, and the speed reduction mechanism part 2 is switched by switching between the deceleration state and the non-deceleration state of the planetary speed reduction mechanism of each stage. Change the overall reduction ratio. In the following description, the first, second, and third stage planetary speed reducing mechanisms will be described in order from the side closer to the motor 1.

  The first-stage planetary speed reduction mechanism includes a sun gear 10 (not shown in FIG. 5) that is rotationally driven about the axis by rotational power from the motor 1, a plurality of planetary gears 11 that mesh with the sun gear 10, A ring gear 12 meshing with the planetary gear 11 is provided. The planetary gear 11 is positioned so as to surround the sun gear 10, and the ring gear 12 is positioned so as to surround the plurality of planetary gears 11. The first-stage planetary reduction mechanism further includes a carrier 14 that is rotatably connected to the plurality of planetary gears 11, and a carrier pin 13 that connects the planetary gear 11 and the carrier 14.

  The second-stage planetary reduction mechanism includes a second-stage sun gear 20 (not shown in FIG. 5) coupled to the first-stage sun gear 10, a plurality of planetary gears 21 meshing with the sun gear 20, A first-stage ring gear 12 capable of meshing with the plurality of planetary gears 21 is provided. The planetary gear 21 is positioned so as to surround the sun gear 20. The second-stage planetary speed reduction mechanism further includes a carrier 24 that is rotatably connected to the plurality of planetary gears 21, and a carrier pin 23 that connects the planetary gear 21 and the carrier 24. The tip is connected to the first stage carrier 14.

  Whether the ring gear 12 functions as a member for forming the first-stage planetary speed reduction mechanism or as a member for forming the second-stage planetary speed reduction mechanism is selected depending on the slide position. This is a selectable structure. That is, the ring gear 12 meshes with the first stage planetary gear 11 when in the sliding position on the motor 1 side, and meshes with the second stage planetary gear 21 when in the sliding position on the output shaft 4 side.

  In the following text, the motor 1 side is simply referred to as “input side”, and the output shaft 4 side is simply referred to as “output side”.

  On the inner peripheral surface of the gear case 9, there is provided a guide portion 15 in which the ring gear 12 is slidably and non-rotatably engaged in the axial direction. The ring gear 12 is guided in the axial direction while being guided by the guide portion 15. Move the slide.

  The third-stage planetary speed reduction mechanism includes a third-stage sun gear 30 coupled to the second-stage carrier 24, a plurality of planetary gears 31 that mesh with the sun gear 30, and a ring that meshes with the plurality of planetary gears 31. The planetary gear 31 is positioned so as to surround the sun gear 30. The planetary reduction mechanism at the third stage further includes a carrier 34 that is rotatably connected to the plurality of planetary gears 31, and a carrier pin 33 that connects the planetary gear 31 and the carrier 34.

  The ring gear 32 is slidably and rotatably arranged in the axial direction with respect to the gear case 9. When the ring gear 32 is in the input-side slide position, the ring gear 32 meshes with the outer peripheral edge of the second stage carrier 24. When the ring gear 32 is in the slide position on the output side, the ring gear 32 meshes with the engaging tooth portion 40 formed integrally with the gear case 9. Further, the ring gear 32 meshes with the planetary gear 31 at any sliding position.

  These three-stage planetary reduction mechanisms are connected in the axial direction. That is, the sun gears 10, 20, and 30 in the first to third stages are arranged side by side on the straight line in the axial direction, and the two ring gears 12 and 32 positioned so as to surround them are also arranged on the straight line in the axial direction. Has been.

  Each of the ring gears 12 and 32 is independently slidable in the axial direction, and the reduction ratio is switched corresponding to the sliding position, and the rotation output of the output shaft 4 is changed to the first speed, the second speed, and the third speed. Thus, in this embodiment, each ring gear 12, 32 forms a switching member 7 that is slidable in the axial direction. The first speed here is the state with the smallest reduction ratio, the second speed is the state where the reduction ratio is larger than the first speed, and the third speed is the state where the reduction ratio is larger than the first and second speeds (that is, the smallest reduction ratio). Big state).

  6 shows the state of the first speed, FIG. 7 shows the state during the switching between the first speed and the second speed, FIG. 8 shows the state of the second speed, FIG. 9 shows the state during the switching between the second speed and the third speed, FIG. Shows the state of the third speed.

  In the speed reduction mechanism section 2 at the first speed in FIG. 6, one ring gear 12 forming the switching member 7 is in the input side position, and the other ring gear 32 forming the switching member 7 is also in the input side position. Therefore, only the first stage planetary speed reduction mechanism is in a deceleration state.

  Specifically, the planetary gear 11 meshing with the ring gear 12 rotates and revolves around the sun gear 10 due to the rotation of the sun gear 10 in the first stage, so that the rotational force of the sun gear 10 is decelerated. It is transmitted to the carrier 14. The carrier 14 rotates integrally with the second stage carrier 24, and the entire third stage planetary speed reduction mechanism also rotates integrally with the second stage carrier 24.

  In the second speed reduction mechanism portion 2 in FIG. 8, one ring gear 12 forming the switching member 7 is at the output side position, and the other ring gear 32 forming the switching member 7 is also at the input side position. Therefore, only the second stage planetary speed reduction mechanism is in a deceleration state.

  Specifically, the rotation of the second stage sun gear 20 coupled to the first stage sun gear 10 causes the second stage planetary gear 21 meshing with the ring gear 12 to rotate and revolve around the sun gear 20. Thus, the rotational force of the sun gear 20 is decelerated and transmitted to the carrier 24. The first-stage and third-stage planetary speed reduction mechanisms rotate integrally with the second-stage carrier 24.

  Here, in the first stage planetary speed reduction mechanism and the second stage planetary speed reduction mechanism, the shape and shape of each member are made different so that the speed reduction ratio is larger in the second stage. Therefore, in the case of the second speed, the reduction ratio is larger than that of the first speed, and the rotation speed of the output shaft 4 is reduced.

  In the speed reduction mechanism portion 2 at the third speed in FIG. 10, one ring gear 12 forming the switching member 7 is at the output side position, and the other ring gear 32 forming the switching member 7 is also at the output side position. Therefore, both the second stage planetary deceleration mechanism and the third stage planetary deceleration mechanism are in a decelerating state.

  Specifically, the rotation of the second stage sun gear 20 coupled to the first stage sun gear 10 causes the second stage planetary gear 21 meshing with the ring gear 12 to rotate and revolve around the sun gear 20. Thus, the rotational force of the sun gear 20 is decelerated and transmitted to the carrier 24. The first stage planetary reduction mechanism rotates integrally with the second stage carrier 24. The rotation of the second stage carrier 24 is transmitted to the third stage sun gear 30 coupled thereto. As the third stage planetary gear 31 meshing with the ring gear 32 rotates and revolves around the sun gear 30 due to the rotation of the third stage sun gear 30, the rotational force of the sun gear 30 is further decelerated. It is transmitted to the carrier 34.

  The sliding positions of the two ring gears 12 and 32 constituting the switching member 7 are both determined according to the rotational position of the transmission cam plate 8. The transmission cam plate 8 is a plate having an arcuate cross section along the outer peripheral surface of the cylindrical gear case 9, and is mounted so as to be rotatable around the central axis of the gear case 9.

  The transmission cam plate 8 has two cam grooves 41 and 42 arranged in parallel in the axial direction. The input side cam groove 41 is a through groove having a polygonal line shape corresponding to the sliding movement of the ring gear 12. The tip of the speed change pin 45 inserted through the cam groove 41 is inserted into the gear case 9 through a guide groove 48 (see FIG. 5) penetrating the gear case 9 and is engaged with the concave groove on the outer peripheral surface of the ring gear 12. Match. The guide groove 48 is formed in parallel with the axial direction of the speed reduction mechanism unit 2.

  The output cam groove 42 is a through groove having a polygonal line shape corresponding to the sliding movement of the ring gear 32. The tip of the speed change pin 46 inserted into the cam groove 42 is inserted into the gear case 9 through a guide groove 49 (see FIG. 5) penetrating the gear case 9, and is engaged with the concave groove on the outer peripheral surface of the ring gear 32. Match. The guide groove 49 is formed in parallel with the axial direction of the speed reduction mechanism portion 2 and is formed in a straight line with the other guide groove 48.

  The speed change cam plate 8 has a gear portion 47 that meshes with the rotary speed change actuator 6 at its circumferential end. The speed change actuator 6 includes a dedicated motor (sub motor) 50, a speed reduction mechanism portion 51 that reduces and transmits the rotational power of the motor 50, and an output portion 52 that is rotationally driven by the rotational power transmitted through the speed reduction mechanism portion 51. And have. That is, the speed change actuator 6 slides the switching member 7 in the axial direction via the speed change cam plate 8.

  As described above, in the electric power tool according to the present embodiment, the speed reduction mechanism unit 2 is engaged with the switching member 7 that is slidable in the axial direction and the switching member 7 according to the sliding position of the switching member 7 in the axial direction. And a gear member 5 that can be switched between a state and a non-engaged state.

  The switching member 7 is the ring gears 12 and 32 as described above. The gear member 5 here is the first stage planetary gear 11 and the second stage planetary gear 21 for the ring gear 12, and the second stage carrier 24 for the ring gear 32. It is the denture part 40. The speed reduction ratio of the entire speed reduction mechanism 2 is switched according to the engagement state and the non-engagement state of the switching member 7 and the gear member 5.

  Further, as schematically shown in FIG. 1, a driving state detection unit 60 that detects the driving state of the motor 1, a load detection unit 61 that detects an operation load state of the speed change actuator 6, and a slide position of the switching member 7. And a slide position detecting unit 63 for detecting.

  The driving state detection unit 60 detects the driving state of the motor 1 by detecting at least one of the current value flowing through the motor 1 and the rotation speed of the motor 1, and inputs the detection result to the control unit 62. The load detection unit 61 detects at least one of the current value flowing through the motor 50 and the rotation speed of the motor 50 to detect the operation load state of the speed change actuator 6 and inputs the detection result to the control unit 62.

  Then, the slide position detection unit 63 detects the rotational position of the speed change cam plate 8 that is linked to the switching member 7 with respect to the gear case 9 to indirectly detect the position of the switching member 7 (that is, each of the ring gears 12 and 32). Slide position) is detected, and the detection result is input to the control unit 62. The slide position detection unit 63 may be a non-contact type displacement detection sensor, or may be a contact type that directly contacts the speed change cam plate 8.

  In addition, the electric tool according to the present embodiment includes a control unit 62 that controls driving of the motor 1 and the motor 50. The control unit 62 activates the speed change actuator 6 according to the driving state of the motor 1 detected by the driving state detection unit 60 and slides the switching member 7 to change the reduction ratio of the speed reduction mechanism unit 2. .

  That is, in the electric power tool of the present embodiment, the speed change actuator 6, the drive state detection unit 60, the load detection unit 61, the slide position detection unit 63, and the control unit 62 that activates the speed change actuator 6 are used. The reduction ratio switching means is configured.

  In the control unit 62, when the speed change actuator 6 (that is, the motor 50) is started, the rotational power of the motor 1 is temporarily changed according to the detection result of the load detection unit 61 and the detection result of the slide position detection unit 63. Is controlled to decrease or increase. Here, the rotational power of the motor 1 is reduced or increased because the relative rotational speed at the time of engagement is reduced as much as possible between the switching member 7 that is slid and the gear member 5 that is engaged after sliding (preferably Because it is zero). That is, the control unit 62 reduces the relative rotational speed of the switching member 7 and the gear member 5 during the reduction ratio switching operation so that the switching member 7 can be easily engaged with the gear member 5 that is the engagement partner (easily engaged). ) To control.

  In the following, automatic transmission from 1st speed to 2nd speed, automatic transmission from 2nd speed to 3rd speed, automatic transmission from 3rd speed to 2nd speed, automatic transmission from 2nd speed to 1st speed Cases will be described in turn.

  The automatic shift from the first speed to the second speed is performed as follows. That is, when the motor 1 is rotationally driven in the first speed state shown in FIG. 6, when the driving state detection unit 60 detects that the load applied to the motor 1 has reached a predetermined level, the second speed is set. Automatic shift.

  Specifically, when the current value flowing through the motor 1 becomes a predetermined value or more, when the rotation speed of the motor 1 becomes a predetermined value or less, or this current value and the rotation speed satisfy a predetermined relationship. Is detected, the load applied to the motor 1 has reached a predetermined level.

  The control unit 62 to which the detection result is input starts the motor 50 of the speed change actuator 6 and rotates the speed change cam plate 8. The speed change pin 45 inserted into the input side cam groove 41 of the speed change cam plate 8 is slid to the output side while being guided by the guide groove 48 provided in the gear case 9. The transmission pin 45 slides the ring gear 12 that is the switching member 7 to the output side.

  The ring gear 12 that has been slid is first disengaged from the first stage planetary gear 11 and is in a state of being switched as shown in FIG. At this time, the ring gear 12 is rotationally fixed with respect to the gear case 9. On the other hand, the second stage planetary gear 21, which is the gear member 5 to be engaged next, is driven to rotate about the axis with respect to the gear case 9 in a form depending on the rotational power of the motor 1.

  When the detection result that the ring gear 12 has reached the predetermined switching state in FIG. 7 is input from the load detection unit 61 and the slide position detection unit 63, the control unit 62 supplies the rotational power of the motor 1 at that time. Decrease temporarily (including zero). As a result, when the ring gear 12 is engaged with the second stage planetary gear 21 as shown in FIG. 8, the relative rotational speed between the two gears 12 and 21 is reduced (preferably zero), and the impact during engagement is reduced. Suppress. Therefore, smooth and stable automatic gear shifting is realized, and gear wear and damage due to a collision are also suppressed.

  The control unit 62 may be a control that reduces the rotational power of the motor 1 to some extent from the time when the speed change actuator 6 is activated. In this case, for example, the control unit 62 gradually decreases the rotational power of the motor 1 in synchronization with the activation of the speed change actuator 6, and detects that the ring gear 12 has reached the predetermined switching state in FIG. When the result is input, the rotational power of the motor 1 is further reduced.

  The automatic shift from the second speed to the third speed is performed as follows. That is, when the motor 1 is rotationally driven in the second speed state shown in FIG. 8, when the driving state detection unit 60 detects that the load applied to the motor 1 has reached a predetermined level, the third speed is set. Automatic shift. Specifically, when the current value flowing through the motor 1 becomes a predetermined value or more, when the rotation speed of the motor 1 becomes a predetermined value or less, or this current value and the rotation speed satisfy a predetermined relationship. Is detected, the load applied to the motor 1 has reached a predetermined level.

  The control unit 62 to which the detection result is input starts the motor 50 of the speed change actuator 6 and rotates the speed change cam plate 8. The speed change pin 46 inserted through the cam groove 42 on the output side of the speed change cam plate 8 is slid to the output side while being guided by a guide groove 49 provided in the gear case 9. The transmission pin 46 slides the ring gear 32, which is another switching member 7, to the output side.

  The ring gear 32 that has been slid is first disengaged from the carrier 24 at the second stage, and reaches a state during switching as shown in FIG. At this time, the ring gear 32 is engaged with the third planetary gear 31 and is not rotationally fixed to the gear case 9.

  The ring gear 32 in the midway of switching in FIG. 9 continues to rotate with the rotational inertia when engaged with the carrier 24 at the second speed, but at the same time, the third stage planet driven by the motor 1. The reaction force from the gear 31 receives a rotational force in the direction opposite to this rotational inertia. On the other hand, the engaging tooth portion 40 which is the gear member 5 to which the ring gear 32 is engaged next is fixed to the gear case 9.

  The controller 62 actively uses the rotational force in the opposite direction to reduce the relative rotational speed between the ring gear 32 and the engagement tooth portion 40 (preferably zero). That is, when the load detecting unit 61 and the slide position detecting unit 63 detect that the ring gear 32 has reached the predetermined switching state in FIG. 9, the control unit 62 temporarily slides the ring gear 32 at that time. Stop. And the rotational power of the motor 1 is increased temporarily, and the rotational speed with respect to the gear case 9 of the ring gear 32 is reduced rapidly. After that, the sliding movement of the ring gear 32 is resumed, and when the engagement with the engagement tooth portion 40 is performed, the rotation speed of the ring gear 32 is adjusted to be as close to zero as possible.

  As a result, as shown in FIG. 10, the impact when the ring gear 32 engages with the engaging tooth portion 40 is suppressed, and a smooth and stable automatic transmission is realized, and the wear and damage of the gear due to the collision are also suppressed. be able to.

  Note that the rotational speed may be adjusted by temporarily increasing the rotational power of the motor 1 without temporarily stopping the sliding movement of the ring gear 32. Further, the rotational speed may be adjusted only by temporarily stopping the ring gear 32. Further, as the control for gradually reducing the rotational power of the motor 1 in synchronization with the activation of the speed change actuator 6 and reducing the rotation due to the rotational inertia of the ring gear 32 when engaged with the carrier 24 at the second speed. Also good.

  The automatic transmission from the 3rd speed to the 2nd speed is controlled as follows. That is, when the motor 1 is rotationally driven in the state of the third speed shown in FIG. 10, when the driving state detection unit 60 detects that the load applied to the motor 1 has reached a predetermined level, the second speed is set. Automatic shift.

  Specifically, when the current value flowing through the motor 1 becomes a predetermined value or less, when the rotation speed of the motor 1 becomes a predetermined value or more, or this current value and the rotation speed satisfy a predetermined relationship. Is detected, the load applied to the motor 1 has reached a predetermined level.

  The control unit 62 to which the detection result is input starts the motor 50 of the speed change actuator 6 and rotates the speed change cam plate 8. The shift pin 46 inserted into the cam groove 42 on the output side of the shift cam plate 8 slides the ring gear 32 that is the switching member 7 to the input side.

  The ring gear 32 that has been slid is first disengaged from the engaging tooth portion 40, and reaches a state during switching as shown in FIG. At this time, the ring gear 32 is engaged with the third planetary gear 31 and is not rotationally fixed to the gear case 9.

  The ring gear 32 in the midway of switching in FIG. 9 receives a rotational force in a direction opposite to the rotational direction of the motor 1 due to the reaction force from the third stage planetary gear 31 driven by the motor 1. On the other hand, the second-stage carrier 24 that is the gear member 5 to which the ring gear 32 is engaged next is rotated in the rotation direction of the motor 1.

  When the detection result that the ring gear 32 has reached the predetermined switching state in FIG. 9 is input from the load detection unit 61 and the slide position detection unit 63, the control unit 62 supplies the rotational power of the motor 1 at that time. Decrease temporarily (including zero). As a result, when the ring gear 32 is engaged with the second stage carrier 24 as shown in FIG. 8, the relative rotational speed between the two gears 32 and 24 is reduced (preferably zero), and the impact at the time of engagement is reduced. Suppress. Therefore, smooth and stable automatic gear shifting is realized, and gear wear and damage due to a collision are also suppressed.

  The control unit 62 may be a control that reduces the rotational power of the motor 1 to some extent from the time when the speed change actuator 6 is activated. In this case, for example, the control unit 62 gradually decreases the rotational power of the motor 1 in synchronization with the activation of the speed change actuator 6 and detects that the ring gear 32 has reached the predetermined switching state in FIG. When the result is input, the rotational power of the motor 1 is further reduced.

  The automatic shift from the second speed to the first speed is performed as follows. That is, when the motor 1 is rotationally driven by the speed reduction mechanism unit 2 in the second speed state shown in FIG. 8, the drive state detection unit 60 detects that the load applied to the motor 1 has reached a predetermined level. Sometimes it is automatically shifted to the first speed. Specifically, when the current value flowing through the motor 1 becomes a predetermined value or less, when the rotation speed of the motor 1 becomes a predetermined value or more, or this current value and the rotation speed satisfy a predetermined relationship. Is detected, the load applied to the motor 1 has reached a predetermined level.

  The control unit 62 to which the detection result is input starts the motor 50 of the speed change actuator 6 and rotates the speed change cam plate 8. The shift pin 45 inserted into the cam groove 41 on the input side of the shift cam plate 8 slides the ring gear 12 as the switching member 7 to the input side.

  The ring gear 12 that has been slid is first disengaged from the planetary gear 21 at the second stage, and is in the middle of switching shown in FIG. At this time, the ring gear 12 is rotationally fixed with respect to the gear case 9. On the other hand, the first stage planetary gear 11, which is the gear member 5 to be engaged next, is driven to rotate about the axis with respect to the gear case 9 in a form depending on the rotational power of the motor 1.

  When the detection result that the ring gear 12 has reached the predetermined switching state in FIG. 7 is input from the load detection unit 61 and the slide position detection unit 63, the control unit 62 supplies the rotational power of the motor 1 at that time. Decrease temporarily. As a result, when the ring gear 12 is engaged with the first stage planetary gear 11 as shown in FIG. 6, the relative rotational speed between the two gears 12 and 11 is reduced (preferably zero), and the impact at the time of engagement is reduced. Suppress. Therefore, smooth and stable automatic gear shifting is realized, and gear wear and damage due to a collision are also suppressed.

  The control unit 62 may be a control that reduces the rotational power of the motor 1 to some extent from the time when the speed change actuator 6 is activated. In this case, for example, the control unit 62 gradually decreases the rotational power of the motor 1 in synchronization with the activation of the speed change actuator 6, and detects that the ring gear 12 has reached the predetermined switching state in FIG. When the result is input, the rotational power of the motor 1 is further reduced.

  As described above, the control unit 62 of the present embodiment activates the speed change actuator 6 according to the driving state of the motor 1 and corresponds to the detected current position of the switching member 7 (ring gears 12 and 32). In this way, the rotational power of the motor 1 is temporarily reduced or increased. This reduction in rotational power includes a case where the motor 1 is stopped. As a result, smooth and stable automatic gear shifting is realized, and wear and damage of the gear due to a collision are also suppressed. The control unit 62 may gradually decrease or increase the rotational power of the motor 1 in synchronization with the activation of the speed change actuator 6.

  In addition, in the control unit 62 of the present embodiment, drive control of the speed change actuator 6 is performed in a manner corresponding to the position of the switching member 7 (ring gears 12 and 32) detected by the load detection unit 61 and the slide position detection unit 63. Also control to change this. As a result, smoother and more stable automatic transmission can be realized, and gear wear and damage due to collision can be further suppressed.

  Hereinafter, the control of the speed change actuator 6 will be specifically described.

  The control unit 62 drives the speed change actuator 6 to move the switching member 7 (ring gear 12 or ring gear 32) to the target gear member 5 (planetary gear 11, planetary gear 21, carrier 24 or engaging tooth portion. 40). At this time, the teeth of the switching member 7 and the gear member 5 may not mesh well, and the switching member 7 may not be able to slide to a predetermined target position. In this case, not only the gear shifting does not work well, but the work is not only obstructed, but an excessive load is applied to the gear shifting actuator 6 to cause a failure.

  On the other hand, the control unit 62 determines that the switching member 7 is not slid to the predetermined target position (shift incomplete) based on the detection results input from the load detection unit 61 and the slide position detection unit 63. When rotating, the rotation direction of the motor 50 is once reversed. That is, the direction in which the switching member 7 is slid through the speed change cam plate 8 is reversed for a predetermined time, and the switching member 7 is once separated from the target gear member 5.

  Since the relative rotational position of the switching member 7 and the gear member 5 is changed by the rotational power from the motor 1 while the two members 7 and 5 are separated from each other, the motor 50 of the speed change actuator 6 is rotated forward again to switch. When the member 7 is slid to the gear member 5 side, both the members 7 and 5 are easily meshed. If the situation where the switching member 7 does not slide to the predetermined target position again occurs, the control unit 62 repeats the same control. It should be noted that when the situation where the slide does not move occurs a predetermined number of times, the control unit 62 that has detected this may stop the driving of the motor 1.

  Alternatively, a detection result that the switching member 7 has reached a state during switching or a detection result that the switching member 7 has not slid to a predetermined target position may be input from only the load detection unit 61.

  Next, other embodiments of the electric power tool of the present invention will be described in order. Detailed description of the same configuration as that of the first embodiment will be omitted, and a characteristic configuration different from that of the first embodiment will be mainly described in detail.

<Embodiment 2>
The electric power tool of this embodiment is also provided to change the drive control of the shift actuator 6 when the gears do not mesh well and the shift fails (when the shift is not completed). As a result, smooth and stable automatic gear shifting is realized, and gear wear and breakage due to collision are also suppressed. However, in the present embodiment, the method for changing the drive control of the speed change actuator 6 is different from that in the first embodiment.

  Specifically, when it is determined from the detection results of the load detection unit 61 and the slide position detection unit 63 that the switching member 7 is not slid to the predetermined target position, the control unit 62 includes the speed change actuator 6. The rotational power of the motor 50 is changed so as to increase. That is, by changing the slide driving force that slides the switching member 7 via the speed change cam plate 8, both members 7 and 5 are easily engaged.

  It should be noted that the rotational power of the motor 50 is not only increased, but also decreased, of course, once increased and decreased, once decreased and increased, and the decrease and increase repeated at a predetermined cycle, etc. An appropriate driving force can be changed. In addition, when the switching member 7 does not slide to the predetermined target position even if the slide driving force is changed, the control unit 62 that detects this may be provided so as to stop driving the motor 1.

<Embodiment 3>
In the electric power tool of the present embodiment, when the gears do not mesh well and the shift fails, the relative rotation position of the switching member 7 and the gear member 5 is changed. As a result, smooth and stable automatic gear shifting is realized, and gear wear and breakage due to collision are also suppressed. However, in the present embodiment, the method of changing the control when the shift fails is different from that in the first embodiment.

  Specifically, when it is determined that the switching member 7 has not slid to the predetermined target position and the motor 1 is not substantially driven, the control unit 62 The drive power of the actuator 6 is maintained and the rotational power of the motor 1 is changed. In other words, the control is such that the switching member 7 is brought to the target position based on the detection results of the load detection unit 61 and the slide position detection unit 63 during the driving of the speed change actuator 6 after the rotational power of the motor 1 is once changed. It is performed when it is determined that the slide is not moved.

  Specifically, when it is determined that the shift is incomplete, and based on the detection result of the drive state detection unit 60, if it is determined that the rotational power of the motor 1 is stopped or substantially stopped and the motor 1 is not substantially driven, the shift is performed. The rotational power of the motor 1 is increased with the drive of the actuator 6 being maintained.

  Furthermore, when increasing the rotational power of the motor 1, the control unit 62 changes the rotational acceleration of the rotational power so that the sliding movement is larger than the sliding movement. That is, compared with the rotational acceleration in the state where the gears are not meshed well and the switching member 7 is not slid, the rotational acceleration in the state where the gears can be meshed with each other and the switching member 7 is slidingly moved is increased. To control.

  In addition, it is possible not only to maintain the rotational power of the motor 50, but also to change the driving force appropriately, such as once decreasing and increasing, or repeating the decrease and increase in a predetermined cycle. In addition, when the switching member 7 does not slide to the predetermined target position even if the slide driving force is changed, the control unit 62 that detects this may be provided so as to stop driving the motor 1.

  The state in which the motor 1 is not substantially driven includes not only the case where the rotational power of the motor 1 is reduced at the time of shifting, but also the state where the operation is determined to be completed by the control unit 62 and the driving of the motor 1 is stopped. Specifically, after the load of the motor 1 reaches a predetermined level, the drive of the motor 1 is stopped when the control unit 62 determines that the work is completed or the operation of the trigger switch 103 is released. It is in the state. In the automatic shift in this state, when the shift is unsuccessful, the control unit 62 drives the stopped motor 1 once.

<Embodiment 4>
Also in the electric power tool of this embodiment, when the gears are not meshed well and the shift fails, the relative rotation position of the switching member 7 and the gear member 5 is changed. As a result, smooth and stable automatic gear shifting is realized, and gear wear and breakage due to collision are also suppressed. However, in the present embodiment, the method of changing the control when the shift fails is different from that in the first embodiment. The point that is implemented when it is determined that the switching member 7 does not slide to the predetermined target position and the motor 1 is not substantially driven is the same as in the third embodiment. However, the control method after the determination is different from the third embodiment.

  Specifically, when it is determined that the speed change is not completed and the motor 1 is not substantially driven, the control unit 62 temporarily stops the drive of the speed change actuator 6 and uses the rotational power of the motor 1. After that, the drive of the shift actuator 6 is started again. That is, when the shift fails, the control unit 62 interrupts the drive of the shift actuator 6, increases the rotational power of the motor 1, and then restarts the drive of the shift actuator 6.

  Furthermore, when increasing the rotational power of the motor 1, the control unit 62 changes the rotational acceleration of the rotational power so that the sliding movement is larger than the sliding movement. That is, compared with the rotational acceleration in the state where the gears are not meshed well and the switching member 7 is not slid, the rotational acceleration in the state where the gears can be meshed with each other and the switching member 7 is slidingly moved is increased. To control.

  Note that it is possible to change the driving force as appropriate, such as increasing the rotational power of the motor 1 instead of increasing it once, increasing it once, and repeating the decrease and increase in a predetermined cycle. In addition, when the switching member 7 does not slide to the predetermined target position even if the slide driving force is changed, the control unit 62 that detects this may be provided so as to stop driving the motor 1.

  The state in which the motor 1 is not substantially driven includes not only the case where the rotational power of the motor 1 is reduced at the time of shifting, but also the state where the operation is determined to be completed by the control unit 62 and the driving of the motor 1 is stopped. Specifically, after the load of the motor 1 reaches a predetermined level, the drive of the motor 1 is stopped when the control unit 62 determines that the work is completed or the operation of the trigger switch 103 is released. It is in the state. In the automatic shift in this state, when the shift is unsuccessful, the control unit 62 drives the stopped motor 1 once.

<Embodiment 5>
In the electric tool of the present embodiment, the slide position detection unit 63 is different from that of the first embodiment. The slide position detection unit 63 of the present embodiment does not detect the position of the other member (transmission cam plate 8) interlocked with the switching member 7 as in the first embodiment, but directly detects the position of the switching member 7. It has a structure to do.

  FIG. 11 schematically shows the slide position detection unit 63 of the present embodiment. In the present embodiment, the speed change actuator 6 is a direct acting actuator composed of a solenoid, and the amount of protrusion of the plunger 70 in the axial direction can be changed. The ring gear 32 constituting the switching member 7 is connected to the plunger 70 via the connecting member 71. The ring gear 32 is rotatable about the axis with respect to the connecting member 71 and is configured to slide in the axial direction integrally with the connecting member 71.

  The slide position detection unit 63 is a displacement detection sensor installed in the gear case 9 so as to be positioned on the radially outer side of the ring gear 32. This sensor is a contact type that directly contacts the ring gear 32, but a non-contact type may also be used.

<Embodiment 6>
Also in the electric tool of the present embodiment, the slide position detection unit 63 is different from that of the first embodiment. The slide position detection unit 63 of the present embodiment does not detect the position of the switching member 7 or other members (transmission cam plate 8) interlocked therewith, but detects the drive state of the transmission actuator 6 and the detection result. Based on this, the position of the switching member 7 is indirectly detected.

  FIG. 12 schematically shows the slide position detector 63 of the present embodiment. The slide position detector 63 of the present embodiment is a displacement sensor that detects the rotational position of the output unit 52 of the rotary transmission actuator 6. As this displacement sensor, a contact type that directly contacts the output unit 52 may be used, or a non-contact type may be used.

<Embodiment 7>
Also in the electric tool of the present embodiment, the slide position detection unit 63 is different from that of the first embodiment. The slide position detection unit 63 of the present embodiment indirectly detects the position of the switching member 7 by detecting the drive state of the speed change actuator 6, and in this respect, is the same as that of the sixth embodiment. . However, this embodiment is different from the sixth embodiment in the following points.

  FIG. 13 schematically shows the slide position detector 63 of the present embodiment. In the present embodiment, the speed change actuator 6 is a direct acting actuator composed of a solenoid, and the amount of protrusion of the plunger 70 in the axial direction can be changed. The ring gear 32 constituting the switching member 7 is connected to the plunger 70 via the connecting member 71. The ring gear 32 is rotatable about the axis with respect to the connecting member 71 and is configured to slide in the axial direction integrally with the connecting member 71.

  The slide position detector 63 is a displacement sensor that detects the protruding position of the plunger 70 included in the direct-acting shift actuator 6. The displacement sensor is a contact type that directly contacts the plunger 70, but a non-contact type may be used.

<Eighth embodiment>
Also in the electric tool of the present embodiment, the slide position detection unit 63 is different from that of the first embodiment. The slide position detector 63 of this embodiment detects only the engagement position state of the switching bar 7 and the gear member 5.

  FIG. 14 schematically shows the slide position detector 63 of the present embodiment. In the present embodiment, the slide position detection unit 63 is a tact switch whose detection result is input to the control unit 62 when pressed, and when the switching member 7 is engaged with the gear member 5, the tact switch is switched to the switching member 7. It is configured to be pushed. The slide position detection unit 63 that detects the engagement position state is a contact type that directly contacts the switching member 7, but a non-contact type such as a photo reflector may also be used.

  So far, the detailed structure of the electric tool of Embodiments 1-8 was demonstrated.

  As described above, the switching member 7 and the gear member are activated according to the operation load state of the shifting actuator 6 detected by the load detecting unit 61 when the shifting actuator 6 is activated and the switching member 7 is slid to some extent. The relative rotational speed of 5 is reduced.

  And by having this structure, the relative rotational speed of the switching member 7 and the gear member 5 can be made as small as possible and meshed, and the automatic reduction ratio change with the motor 1 being driven to rotate can be performed. It can be completed smoothly in a short time. Furthermore, since the relative rotational speed is made as small as possible, the impact of engagement when changing the reduction ratio can be suppressed.

  Further, since the slide position detection unit 63 is also provided, the reduction ratio change is controlled by using the detection result of the load detection unit 61 and the detection result of the slide position detection unit 63 in combination. The control unit 62 changes the drive control of the speed change actuator 6 in addition to the reduction in the relative rotational speed of the switching member 7 and the gear member 5.

  That is, control is performed so as to reduce the relative rotational speed of the switching member 7 and the gear member 5 and the drive control of the shifting actuator 6 is changed according to the operating load of the shifting actuator 6 and the sliding position of the switching member 7. It is possible. Therefore, the automatic reduction ratio change while the motor 1 is driven to rotate can be completed more smoothly, and the control unit 62 can also detect whether the switching member 7 is meshing well with the gear member 5. it can.

  Further, in the electric tools of the first and fifth embodiments, the control unit 62 determines that the load detecting unit does not slide the switching member 7 to the predetermined target position when the shift actuator 6 is driven. When judged based on the detection result 61 and the detection result of the slide position detector 63, the sliding direction of the switching member 7 by the speed change actuator 6 is once reversed. As a result, when it is detected that the switching member 7 does not mesh well with the gear member 5, the switching member 7 is once separated from the gear member 5, the relative rotational positions of both the members 7, 5 are changed, and then the meshing is performed again. Matching can be attempted, making it easier to engage.

  In the electric power tool of the second embodiment, the control unit 62 determines that the detection result of the load detection unit 61 and the switching member 7 are not slid to the predetermined target position when the shift actuator 6 is driven. When the determination is made based on the detection result of the slide position detector 63, the slide driving force of the switching member 7 by the speed change actuator 6 is changed. As a result, when the switching member 7 does not mesh well with the gear member 5, for example, by changing the driving force of the speed change actuator 6, the both members 7, 5 are shifted to a state where they can easily mesh. Can do.

  In the electric power tool of the third embodiment, the controller 62 determines that the detection result of the load detector 61 and the switching member 7 are not slid to the predetermined target position when the shift actuator 6 is driven. When it is determined from the detection result of the slide position detector 63, the relative rotational position of the switching member 7 and the gear member 5 is changed in a state where the sliding drive of the switching member 7 by the speed change actuator 6 is maintained. . As a result, the switching member 7 can be easily engaged with the gear member 5, and when the switching member 7 and the gear member 5 are easily engaged with each other, the switching member 7 can be slid and moved quickly. The ratio change can be completed smoothly in a short time.

  In the electric power tool of the fourth embodiment, when the control unit 62 drives the speed change actuator 6, if the switching member 7 does not slide to the predetermined target position, the detection result of the load detection unit 61 and When judged based on the detection result of the slide position detector 63, the relative rotational position of the switching member 7 and the gear member 5 is changed in a state where the sliding drive of the switching member 7 by the speed change actuator 6 is stopped. . Thereby, when the switching member 7 does not mesh well with the gear member 5, the sliding movement of the switching member 7 is temporarily stopped, the relative rotational position of the switching member 7 and the gear member 5 is easily changed, and the relative After changing the rotational position, it is possible to try the meshing again.

  In the electric tools of the third and fourth embodiments, when the rotational power of the motor 1 is increased and the relative rotational position of the switching member 7 and the gear member 5 is changed, the control unit 62 rotates to increase the rotational power. The acceleration is increased when it is determined that the switching member 7 is sliding, compared to when it is determined that the switching member 7 is not sliding. Thereby, it becomes easy to return the rotational power of the motor 1 to the state which can be used for work, and the switching time required for changing the reduction ratio can be shortened.

  Moreover, in the electric tool of Embodiment 1-5, the slide position detection part 63 detects the position of the switching member 7 or the member linked with this. Thereby, the actual slide position of the switching member 7 can be detected more directly.

  In the electric tools of the sixth and seventh embodiments, the slide position detection unit 63 detects the drive state of the speed change actuator 6 and indirectly detects the position of the switching member 7 based on the detection result. It has become. Thereby, the freedom degree of selection becomes high about the arrangement | positioning location, kind, etc. of the sensor which makes the slide position detection part 63. FIG.

  Furthermore, in the electric tool of the sixth embodiment, the speed change actuator 6 is a rotary actuator, and the slide position detection unit 63 detects the rotation state of the speed change actuator 6. Thereby, the sensor which makes the slide position detection part 63 can be comprised compactly with the form which contacted or approached the actuator 6 for speed change.

  In the electric tool according to the seventh embodiment, the speed change actuator 6 is a direct acting actuator, and the slide position detection unit 63 detects the direct movement state of the speed change actuator 6. Also by this, the sensor which makes the slide position detection part 63 can be comprised compactly with the form which contacted or approached the actuator 6 for speed change.

  In the electric tool of the eighth embodiment, the slide position detection unit 63 detects that the switching member 7 has reached the engagement state position with the gear member 5, and determines the state in which both members 7 and 5 are engaged. It is to be detected. Thereby, compared with the sensor which detects the position of the switching member 7 or the member linked with this continuously, it can comprise at low cost and can suppress cost.

  In the electric power tool of each embodiment, the relative rotational speed and the relative rotational position of the switching member 7 and the gear member 5 are changed by decreasing or increasing the rotational power of the motor 1. It is not restricted to adjusting the relative rotational speed by changing the rotational power of 1. For example, power means for changing the rotational speed or relative rotational position of the switching member 7 is provided separately from the motor 1 and the driving of the power means is controlled to reduce the relative rotational speed of the switching member 7 and the gear member 5. Also good. Of course, the speed change actuator 6 may also serve as power means, such as by using the motor 50 to reduce the relative rotational speed.

  In addition, the state in which the rotational power of the motor is stopped when the speed change is unsuccessful means that the motor is stopped in advance and the reduction ratio is initialized for the next work at the end of the work by the electric tool. For example, the state of returning from the third speed to the first speed is also included. In other words, when the gear ratio is failed when the operation of the reduction ratio is performed in a state where the driving of the motor 1 is stopped at the end of the operation, the control unit 61 drives the motor 1 to increase the rotational power. It has become a thing. As a result, the reduction ratio can be quickly initialized, and the working efficiency of the power tool can be improved.

  The present invention has been described above based on the embodiments shown in the accompanying drawings. However, the present invention is not limited to each embodiment, and within the intended scope of the present invention, an appropriate design can be used in each embodiment. It is possible to apply changes and to combine the configurations of the embodiments as appropriate.

  In addition, as long as the reduction ratio is switched using the speed change actuator 6, it is not limited to the automatic speed change type electric tool that activates the speed change actuator 6 according to the detection result of the drive state detection unit 60 as in the present embodiment. Absent. For example, the control unit 62 may activate the speed change actuator 6 when the control unit 62 receives a reduction ratio switching command by an external operation or the like of an operator.

DESCRIPTION OF SYMBOLS 1 Motor 2 Deceleration mechanism part 5 Gear member 6 Shifting actuator 7 Switching member 61 Slide position detection part 62 Control part 63 Load detection part

Claims (9)

A power tool comprising: a motor as a drive source; a speed reduction mechanism that transmits the rotational power of the motor after being decelerated; and a speed reduction ratio switching unit that switches a speed reduction ratio of the speed reduction mechanism,
The speed reduction mechanism unit uses a switching member that is slidable in the axial direction, and a gear member that is switched between an engagement state and a non-engagement state with the switching member in accordance with an axial slide position of the switching member. The speed reduction ratio is switched,
The reduction ratio switching means includes a shift actuator that slides the switching member in the axial direction, a load detection unit that detects an operation load state of the shift actuator, and activates the shift actuator and A power tool comprising: a control unit that reduces a relative rotational speed of the switching member and the gear member according to a detection result. The electric power tool according to claim 1, wherein the control unit further changes drive control of the shift actuator according to a detection result of the load detection unit. The electric power tool according to claim 2, wherein the reduction ratio switching unit further includes a slide position detection unit that detects a slide position of the switching member. The control unit determines from the detection result of the load detection unit and the detection result of the slide position detection unit that the switching member is not slid to a predetermined target position when the shift actuator is driven. The power tool according to claim 3, wherein when the operation is performed, the sliding direction of the switching member by the shift actuator is temporarily reversed. The control unit determines from the detection result of the load detection unit and the detection result of the slide position detection unit that the switching member is not slid to a predetermined target position when the shift actuator is driven. The power tool according to claim 3, wherein when the operation is performed, a slide driving force of the switching member by the shift actuator is changed. The control unit determines from the detection result of the load detection unit and the detection result of the slide position detection unit that the switching member is not slid to a predetermined target position when the shift actuator is driven. 4. The electric motor according to claim 3, wherein when the operation is performed, the relative rotation position of the switching member and the gear member is changed in a state in which the sliding drive of the switching member by the shift actuator is maintained. tool. The control unit determines from the detection result of the load detection unit and the detection result of the slide position detection unit that the switching member is not slid to a predetermined target position when the shift actuator is driven. 4. The electric motor according to claim 3, wherein when the operation is performed, the relative rotation position of the switching member and the gear member is changed in a state in which the sliding drive of the switching member by the shift actuator is stopped. tool. 7. The control unit according to claim 6, wherein the controller is configured to increase the rotational power and change the relative rotational position when it is determined that the rotational power is reduced or stopped. Item 8. The electric tool according to Item 7. The controller is configured to increase the rotational acceleration that increases the rotational power when the switching member is slid compared to when the switching member is not slid. The power tool according to claim 8.

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