JP2019150897A - Electric tool - Google Patents

Abstract

To provide an electric tool that can be improved in workability while performing control by which a kickback generated in an electric tool main body is detected and driving of a motor is stopped.SOLUTION: The electric tool comprises a controller 51A that can switch control of a motor 3 between first control by which driving of the motor 3 is stopped when at least either one of a first condition relating to rotation speed detected by a detecting part in a state where the motor 3 is driven and a second condition relating to acceleration detected by the detecting part is satisfied and second control by which the driving of the motor 3 is continued even if the at least either one of the first condition and the second condition is satisfied. The controller 51A, after predetermined time elapses after driving of the motor is started, switches control of the motor 3 from the second control to the first control.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a power tool.

  Conventionally, a drilling hole is formed in a workpiece (for example, concrete, steel, wood, etc.) by rotating the tip tool by driving a motor, or crushing by applying a striking force to the tip tool. Electric tools are widely known. As an example of such an electric tool, as an operation mode, an impact mode in which only the impact force is applied to the tip tool and the workpiece is crushed, the above impact force is applied to the tip tool, and a rotational force is transmitted to the tip tool. A hammer drill that can be mechanically switched between a rotation mode and a striking mode in which a workpiece is drilled by rotating a tip tool is known.

  In such a hammer drill, the tip tool may be caught in a hard part of the workpiece during drilling in the rotation / blow mode, and the tip tool may be locked. As a result, workability may be deteriorated.

  In order to cope with the kickback, a hammer drill is known in which a clutch mechanism is provided on the driving force transmission path so as to cut off transmission of the driving force. For example, the hammer drill disclosed in Patent Document 1 is configured such that two or more slip clutches having different slip characteristics are disposed on a rotation transmission path, and the slip clutch to be operated can be selected. Similarly, in order to cope with the kickback, the acceleration generated in the electric tool body is detected, and when the acceleration exceeds the threshold, it is determined that the kickback has occurred, and the control unit stops the rotation of the motor. Hammer drills that perform swing prevention control are known. Further, it is known that the clutch mechanism and the swing prevention control are used in combination.

JP 2002-254224 A

  On the other hand, in a large-sized electric tool, there is a demand for driving the tip tool with a torque near a boundary where the load torque is large and the clutch mechanism interrupts (actuates) the transmission of the rotational force. However, in the electric tool having the clutch mechanism as described above and performing the swing prevention control as described above, depending on the work content of the electric tool, before a sufficient time has elapsed for the clutch mechanism to operate. In other words, there is a possibility that the control unit detects kickback while the motor rotation speed is low and torque is not sufficiently generated, and stops driving of the motor, thereby reducing workability.

  Therefore, an object of the present invention is to provide an electric tool capable of improving workability while performing control for detecting kickback generated in the electric tool body and stopping driving of the motor.

  In order to solve the above-described problems, the present invention provides a housing, a motor housed in the housing and having a rotating shaft, an output unit that is driven by the motor and to which a tip tool can be attached and detached, and between the motor and the output unit. A power transmission unit having a clutch mechanism capable of transmitting the driving force of the motor to the output unit and interrupting transmission of the driving force when a load greater than a predetermined value is applied to the output unit; A detection unit that detects at least one of a rotational speed of a shaft and an acceleration generated in the housing; a first condition relating to the rotational speed detected by the detection unit when the motor is driven; and the detection unit A first control for stopping driving of the motor when at least one of the second conditions relating to the acceleration detected by the step is satisfied; A control unit capable of switching the control of the motor between the second control for continuing the driving of the motor even when at least one of the first condition and the second condition is satisfied, The control unit provides an electric tool characterized in that the control of the control unit is switched from the second control to the first control after a predetermined time has elapsed from the start of driving of the motor.

  According to the electric tool having the above-described configuration, the first control for stopping the motor drive is not performed for a predetermined time from the start of the motor drive, so that a kickback occurs when an operation with a large load torque is performed. In this case, the operator holding the electric power tool main body is sufficiently pressed against the workpiece by the tip tool, and the clutch mechanism generates a predetermined torque that can interrupt (activate) the transmission of the driving force of the motor. In such a case, the operation can be continued without stopping the motor by operating the clutch mechanism during a predetermined time. In addition, when the operator holding the power tool body is not sufficiently pressed against the workpiece by the tip tool, and the predetermined torque is not applied to the clutch mechanism, the control of the control unit performs the first control after a predetermined time has elapsed. It is possible to stop the driving of the motor. Thereby, workability | operativity can be improved.

  In the above configuration, the predetermined time is determined based on characteristics of the clutch mechanism, and the clutch mechanism interrupts transmission of the driving force when a load greater than the predetermined value is applied to the output unit. It is preferable that the time is sufficient.

  According to such a configuration, the first control for stopping the driving of the motor is not performed based on the characteristics of the clutch for a time sufficient for the clutch to interrupt the transmission of the driving force from the start of the driving of the motor. Therefore, when a kickback occurs during work with a large load torque, the operator holding the power tool body is sufficiently pressed against the workpiece by the tip tool, and the clutch mechanism When a predetermined torque that can cut off the transmission of the torque is applied to the clutch mechanism, the clutch mechanism cuts off the transmission of the rotational force during a predetermined time, so that the operation can be continued without stopping the motor. Become. Thereby, workability | operativity can be improved.

  The predetermined time is preferably 50 ms or more and less than 200 ms.

  According to such a configuration, workability can be further improved.

  The power transmission unit may generate a striking force in the first direction on the tip tool by converting the rotational movement of the rotating shaft into a reciprocating motion in the first direction and striking the tip tool. And capable of generating a rotational force in the second direction intersecting the first direction in the tip tool by transmitting the rotational movement of the rotary shaft to the output unit, The power transmission state can be switched between a first power transmission state in which the impact force is transmitted while the rotational force is not transmitted and a second power transmission state in which at least the rotational force is transmitted to the tip tool, It is preferable that the clutch mechanism is provided on a transmission path of the rotational force.

  According to such a configuration, in accordance with the number of rotations of the rotating shaft of the motor and the acceleration generated in the housing that greatly change when kickback occurs in the drilling operation in the second power transmission state in which the rotational force is transmitted to the tip tool. In order to stop the drive of the motor, only the striking force is transmitted to the tip tool, and the impact of the worker during the chiseling operation in the first power transmission state in which the change in the rotational speed of the motor rotation shaft is small compared with the drilling operation. Unexpected motor drive stop due to a change in acceleration caused by a swinging operation or the like of the work implement body is suppressed, and workability is improved.

  In addition, the first condition is that the rotational speed is smaller than a first threshold value relating to the rotational speed, and the second condition is that the acceleration in the second direction generated in the housing is greater than a second threshold value. It is preferable that the condition is also large.

  According to such conditions, it is possible to accurately detect the kickback that occurs during the drilling operation and to suitably stop the motor.

  Moreover, it is preferable that the said control part stops the said motor regardless of whether the said 2nd condition is satisfy | filled when the said 1st condition is satisfy | filled after the said predetermined time progress.

  According to such a configuration, the rotating shaft according to the number of rotations (rotational speed) of the rotating shaft of the motor that greatly changes when a kickback occurs in the drilling operation in the second power transmission state in which the rotational force is transmitted to the tip tool. In order to stop the rotation of the power tool, only the striking force is transmitted to the tip tool, and the power tool of the operator during the chiseling operation in the first power transmission state in which the change in the rotational speed of the motor rotation shaft is small compared with the drilling operation. Unexpected motor drive stop due to the swinging operation of the main body is suppressed, and workability can be improved.

  The control unit preferably stops the motor when the first condition is satisfied and the second condition is satisfied after the predetermined time has elapsed.

  According to such a configuration, since the motor driving is stopped when the condition regarding the acceleration generated in the housing is satisfied at the same time as the condition regarding the rotation speed of the rotating shaft is satisfied, the driving of the motor is more accurately performed. The kickback that occurs during the drilling operation can be detected and the drive of the motor can be stopped. As a result, only the striking force is transmitted to the tip tool, and the operator swings the power tool body during the chiseling operation in the first power transmission state in which the change in the rotational speed of the motor rotation shaft is small compared with the drilling operation. An unexpected stop of the motor drive due to a change in acceleration caused by the above or the like is suppressed, and workability can be improved.

  In addition, after the control unit starts executing the first process for determining whether the acceleration detected by the detection unit satisfies the second condition, the rotation number detected by the detection unit is It is preferable to execute a second process for determining whether or not the first condition is satisfied.

  When a kickback occurs, the rotational speed generally decreases with an increase in acceleration. According to such a configuration, the control unit determines whether or not the second condition regarding acceleration is satisfied first. It is possible to effectively use a data storage area such as a RAM.

  Moreover, it is preferable to further have a switching operation unit that can be manually operated and mechanically switch the power transmission state of the power transmission unit.

  According to the above configuration, since the driving of the motor is stopped according to at least one of the rotational speed (rotational speed) of the rotating shaft of the motor and the acceleration generated in the housing, the power transmission state of the electric tool as described above In the case where the switching operation unit is mechanically switched, there is no need to provide a sensor or the like for determining the power transmission state in the switching operation unit. That is, it is possible to detect kickback that occurs during drilling work in the second power transmission state without increasing the number of parts.

  According to the electric tool of the present invention, it is possible to improve workability while performing control for detecting kickback generated in the electric tool main body and stopping driving of the motor.

It is a whole sectional view showing an internal structure of a hammer drill concerning a 1st embodiment of the present invention. It is an expanded sectional view of a torque transmission mechanism and a clutch mechanism. It is the III-III sectional view taken on the line of FIG. 1 is a plan view of a hammer drill according to a first embodiment of the present invention. FIG. 2 is a partial enlarged cross-sectional view of FIG. 1, showing a mode in which the acceleration sensor support portion of the hammer drill according to the first embodiment of the present invention supports the acceleration sensor. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5 and shows a mode in which the acceleration sensor support portion of the hammer drill according to the first embodiment of the present invention supports the acceleration sensor. It is the arrow VII direction view of FIG. 1, and the aspect which the acceleration sensor support part of the hammer drill concerning the 1st Embodiment of this invention supports an acceleration sensor is shown. It is a circuit diagram which shows the electrical constitution of the hammer drill concerning the 1st Embodiment of this invention. It is a flowchart which shows the drive control of the motor by the controller of the control part of the hammer drill concerning the 1st Embodiment of this invention. (A) is a graph which shows the relationship between the elapsed time from the time of a motor drive start at the time of the operation | work using the hammer drill concerning embodiment of this invention, and the rotation speed of the rotating shaft of a motor, (b), It is a graph which shows the relationship between the elapsed time from the time of a motor drive start, and the acceleration of the rotation direction which generate | occur | produces in a housing. (A) is a figure which shows the state of the clutch mechanism at the time of a normal operation | work, (b) is a figure which shows the mode of operation | movement of a clutch mechanism when the load beyond a predetermined value is applied to a front-end tool. It is a flowchart which shows the drive control of the motor by the controller of the control part of the hammer drill concerning the 2nd Embodiment of this invention.

  A hammer drill 1 that is an example of an electric power tool according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 11. The hammer drill 1 is an electric power tool for forming a drilled hole in a workpiece (for example, concrete, steel, wood, etc.) or crushing it by applying a striking force. The hammer drill 1 has two modes of operation: a “rotation / striking mode” in which the tip tool P rotates and pierces the workpiece and strikes the workpiece, and a “blow mode” in which the tip tool P strikes the workpiece. ".

  In the following description, “up” shown in FIG. 1 is defined as an upward direction, “down” is defined as a downward direction, “front” is defined as a forward direction, and “rear” is defined as a backward direction. Further, when the hammer drill 1 is viewed from the rear, “right” is defined as the right direction, and “left” is defined as the left direction. References to dimensions, numerical values, and the like in this specification include not only dimensions and numerical values that completely match the relevant dimensions and numerical values, but also substantially identical dimensions and numerical values (for example, within the range of manufacturing errors). ). The same applies to “same”, “perpendicular”, “parallel”, “match”, “same”, “constant”, etc. It includes “substantially equal”, “substantially constant”, and the like.

  As shown in FIG. 1, the hammer drill 1 includes a housing 2, a motor 3, an inverter circuit board part 4, a control part 5, a power transmission part 6, an output part 7, an acceleration sensor 8, An operation mode switching unit 9 is mainly included.

  As shown in FIG. 1, the housing 2 includes a motor housing 21, a gear housing 22, a back cover 23, a handle housing 24 to which the battery pack Q can be attached and detached, and an acceleration sensor support portion 25. ing. The housing 2 is an example of the “housing” in the present invention.

  The motor housing 21 has a substantially cylindrical shape extending in the vertical direction, and houses the motor 3 and the inverter circuit board portion 4.

  The motor 3 is a DC brushless motor, and includes a rotating shaft 31, a rotor 32, a stator 33, and a fan 34. The motor 3 is an example of the “motor” in the present invention.

  The rotary shaft 31 extends in the vertical direction and is rotatably supported by the housing 2 via a plurality of bearings. A pinion 31 </ b> A that rotates integrally with the rotation shaft 31 is fixed to the upper end portion of the rotation shaft 31. Gear teeth are formed on the pinion 31A. The rotating shaft 31 is an example of the “rotating shaft” in the present invention.

  The rotor 32 is a rotor having a permanent magnet (not shown), and is provided on the rotary shaft 31 so as to be rotatable integrally with the rotary shaft 31.

  The stator 33 is a stator having a stator winding 33A (FIG. 8). The stator 33 is fixed to the inner peripheral surface of the motor housing 21. Further, the stator winding 33A has three-phase coils U, V, and W that are star-connected.

  The fan 34 is fixed to the rotary shaft 31 so as to be integrally rotatable with the rotary shaft 31 below the pinion 31A. A magnet 34 </ b> A is fixed to the lower portion of the fan 34.

  The inverter circuit board portion 4 is provided above the stator 33 of the motor 3. The inverter circuit board unit 4 has a board 40. On the substrate 40, a switching circuit 41 for supplying the electric power of the battery pack Q to the motor 3 and controlling the rotation of the motor 3, a magnetic sensor unit 42 capable of detecting the magnetic field of the magnet 34A of the fan 34, and the like are mounted. (See FIG. 8).

  The gear housing 22 is made of metal, is connected to the upper portion of the motor housing 21, and extends in the front-rear direction. The gear housing 22 accommodates therein the power transmission unit 6, the output unit 7, and a part of the operation mode switching unit 9. Further, a side handle 2 </ b> A that is held by an operator is attached to the gear housing 22.

  The power transmission unit 6 is interposed between the motor 3 and the output unit 7. The power transmission unit 6 includes a power conversion mechanism 61 and a rotational force transmission mechanism 62 having a substantially cylindrical shape extending in the vertical direction and having a bevel gear formed at the upper end portion. The rotary motion of the rotary shaft 31 is converted into a reciprocating motion in the front-rear direction, and the output unit 7 hits the tip tool P, so that the tip tool P can generate a striking force in the front-back direction. By transmitting this rotational motion to the output unit 7, it is possible to generate a rotational force in the rotational direction about the axis A on the tip tool P. Moreover, the power transmission part 6 is comprised so that the drive state of the front-end tool P can be changed by switching a power transmission state. Specifically, the power transmission unit 6 has a “blow mode” in which a striking force is transmitted to the tip tool P while a rotational force is not transmitted, and a “rotation / striking” in which a striking force and a rotational force are transmitted to the tip tool P. The power transmission state can be switched between “mode” and “mode”. It should be noted that the power transmission state is between the “blow mode” in which the striking force is transmitted to the tip tool but no rotational force is transmitted and the “rotation mode” in which the striking force is not transmitted to the tip tool. It may be configured to be switchable. In the following description, the “rotation direction about the axis A” is simply referred to as “rotation direction”. As shown in FIG. 3, the rotational force transmission mechanism 62 is formed with a groove that is recessed in a substantially rectangular shape radially inward from the outer peripheral surface and extends in the vertical direction. The power transmission unit 6 is an example of the “power transmission unit” in the present invention. The front-rear direction is an example of the “first direction” in the present invention, and the rotation direction is an example of the “second direction intersecting the first direction” in the present invention. The batting mode is an example of the “first power transmission state” in the present invention, and the rotary batting mode is an example of the “second power transmission state” in the present invention.

  As shown in FIGS. 1 to 3, the power transmission unit 6 has a clutch mechanism 63. The clutch mechanism 63 is interposed between the motor 3 and the output unit 7. Specifically, the clutch mechanism 63 is provided in the rotational force transmission mechanism 62. In other words, the clutch mechanism 63 is provided on the transmission path of the rotational force of the rotation shaft of the motor 3. The clutch mechanism 63 is configured to be able to transmit the driving force of the motor 3 to the output unit 7 and to block transmission of the driving force of the motor 3 to the output unit 7. The clutch mechanism 63 is an example of the “clutch mechanism” in the present invention.

  As shown in FIG. 3, the clutch mechanism 63 includes an outer ring portion 63A, an inner ring portion 63B, a plurality of springs 63C, a plurality of balls 63D, and a key member 63E.

  The outer ring portion 63A has a substantially cylindrical shape extending in the vertical direction, and gear teeth that mesh with the gear teeth of the pinion 31A provided on the rotating shaft 31 of the motor 3 are formed on the outer periphery thereof. The outer ring portion 63A has a plurality of engaging portions 63F.

  The plurality of engaging portions 63F are provided approximately every 36 degrees in the circumferential direction of the outer ring portion 63A. That is, in the present embodiment, ten engaging portions 63F are provided. Each of the plurality of engaging portions 63F has a surface that is recessed outward in the radial direction of the outer ring portion 63A as it proceeds from the downstream side to the upstream side in the rotation direction of the outer ring portion 63A (the direction of arrow B in FIG. 3). Yes. Further, a protrusion projecting radially inward from the inner periphery of the outer ring portion 63A is provided at the upstream end portion in the arrow B direction of each engaging portion 63F. The protrusion of each engagement portion 63F is configured to be able to engage with each ball 63D.

  The inner ring portion 63B is formed in a substantially disc shape with a hole formed in the center thereof, and is located radially inward of the outer ring portion 63A. A plurality of grooves 63a are formed in the inner ring portion 63B so as to extend radially in plan view at intervals of approximately 36 degrees in the circumferential direction. That is, in the present embodiment, the grooves 63a are formed at 10 places every 36 degrees. A set of springs 63C and balls 63D are arranged in each groove 63a. The inner ring portion 63B has a cylindrical portion 63G. A through hole may be used instead of the groove 63a.

  The cylindrical portion 63G is formed in a substantially cylindrical shape that extends in the vertical direction. An insertion hole 63b having the same diameter as the outer diameter of the rotational force transmission mechanism 62 is formed in the cylindrical portion 63G so as to extend in the vertical direction. Further, the cylindrical portion 63G is formed with a groove that is recessed in a substantially rectangular shape radially outward from the inner peripheral surface thereof and extends in the vertical direction.

  The key member 63E is a member formed in a prismatic shape extending in the vertical direction. In the present embodiment, the key member 63E is disposed in a space defined by the groove formed in the cylindrical portion 63G and the groove formed in the rotational force transmission mechanism 62, so that the inner ring portion 63B has a rotational force. The transmission mechanism 62 is configured so as not to rotate relative to the transmission mechanism 62. In other words, the inner ring portion 63B and the rotational force transmission mechanism 62 can rotate together.

  Each of the plurality of springs 63C is disposed in each of the plurality of grooves 63a of the inner ring portion 63B so as to extend radially in plan view. That is, in this embodiment, ten springs 63C are provided. Each spring 63C is immovable in the circumferential direction of the inner ring portion 63B. An end portion of each spring 63C located radially inward of the inner ring portion 63B is seated on the outer peripheral surface of the cylindrical portion 63G.

  Each of the plurality of balls 63D is disposed in each of the plurality of grooves 63a of the inner ring portion 63B. That is, in the present embodiment, ten balls 63D are provided. Each ball 63D is immovable in the circumferential direction of the inner ring portion 63B with respect to the inner ring portion 63B. Each ball 63D is in contact with the radially outer end of each spring 63C. In the present embodiment, each ball 63D receives a biasing force radially outward from each spring 63C, so that each ball 63D is engaged with a protrusion of each engagement portion 63F of the outer ring portion 63A. Is configured to be held.

  In addition, when a load torque sufficient to operate the clutch mechanism 63 (a load torque applied to the tip tool P or a load torque applied to the motor 3 via the tip tool P) is applied, the clutch mechanism 63 is connected to the motor 3. The time required to cut off the transmission of the rotational force is determined based on the characteristics of the clutch mechanism 63, and is 50 to 70 [ms] in the present embodiment (see FIG. 10). In this specification, “the clutch mechanism operates” is synonymous with “the clutch mechanism operates so as to cut off transmission of driving force (or rotational force)”.

  As shown in FIG. 1, the output unit 7 is disposed above the rotational force transmission mechanism 62 in the gear housing 22 and is driven by the motor 3. The output unit 7 includes a striker 71, a cylinder 72, and a mounting part 73 to which the tip tool P can be attached and detached.

  The striker 71 is configured to be able to reciprocate by the power conversion mechanism 61. Specifically, the front end of the striker 71 is configured to be able to contact the rear end of the tip tool P mounted on the mounting portion 73, and the tip tool P is reciprocated in the front-rear direction. The striking force is transmitted to.

  The cylinder 72 is configured to be rotatable about the axis A (in the rotational direction) by receiving the rotational force of the motor 3 via the rotational force transmission mechanism 62. Further, the mounting portion 73 is rotated by the rotation of the cylinder 72, and the tip tool P mounted on the mounting portion 73 is configured to be rotatable about the axis A (in the rotation direction).

  As shown in FIGS. 1 and 4, the operation mode switching unit 9 is located at the upper part of the rear portion of the gear housing 22 and is configured to be able to mechanically switch the power transmission state of the power transmission unit 6. . More specifically, the operation mode switching unit 9 transmits the rotational motion to the output unit 7 via the rotational force transmission mechanism 62 and transmits the rotational motion to the output unit 7 via the rotational force transmission mechanism 62. By switching the state to be shut off, the striking mode and the rotation / striking mode can be switched. Moreover, in this Embodiment, the transmission of the striking force to the tip tool P via the power conversion mechanism 61 at the time of work is comprised so that interruption | blocking is impossible. As shown in FIG. 1, the operation mode switching unit 9 includes an operation unit 91 and a sleeve 92. The operation mode switching unit 9 is an example of the “switching operation unit” in the present invention.

  The operation unit 91 is a part operated by an operator when switching the operation mode, and has a substantially circular shape in a top view as shown in FIG. The operation unit 91 is configured to be rotatable in the clockwise direction and the counterclockwise direction of FIG.

  As shown in FIG. 1, the sleeve 92 has a substantially cylindrical shape extending in the front-rear direction. A bevel gear that can mesh with the bevel gear of the rotational force transmission mechanism 62 is formed at the front end of the sleeve 92. The inner diameter of the sleeve 92 is configured to be slightly larger than the outer diameter of the cylinder 72. A cylinder 72 is inserted through the sleeve 92. The sleeve 92 is configured to be movable relative to the cylinder 72 in the front-rear direction in response to an operation on the operation unit 91 (the rotation of the operation unit 91 in the clockwise direction in FIG. 4 or the rotation in the counterclockwise direction). Yes. The sleeve 92 is configured to be able to rotate integrally with the cylinder 72.

  The back cover 23 extends in the vertical direction and is disposed so as to cover the rear portions of the motor housing 21 and the gear housing 22. The back cover 23 is provided with an insertion portion 23A and a connection portion 23B. Further, the lower portion of the back cover 23 covers the acceleration sensor 8.

  The inserted portion 23 </ b> A protrudes rearward at the lower portion of the back cover 23. A through-hole penetrating in the left-right direction is formed in the insertion portion 23A.

  The connection portion 23 </ b> B extends in the front-rear direction at the upper end portion of the back cover 23.

  A control unit 5 is fixed in the back cover 23. The control unit 5 is configured to perform various controls of the hammer drill 1. The control unit 5 has a flat board 51, and various circuits for controlling the hammer drill 1 are mounted on the board (see FIG. 8).

  As shown in FIG. 1, the handle housing 24 has a substantially U-shape when viewed from the side, and is located behind the back cover 23. The handle housing 24 includes a grip portion 24A, a first connection portion 24B, and a second connection portion 24C.

  The grip portion 24A is a portion that is gripped by an operator during work and extends in the vertical direction. A manually operable trigger 24D for controlling the start and stop of the motor 3 is provided on the upper front portion of the grip portion 24A. A switch mechanism (not shown) connected to the control unit 5 is provided inside the gripping unit 24A. When the trigger 24D is pulled, that is, started (for example, pushed into the handle housing 24 by an operator's finger), the switch mechanism outputs a tool start signal for starting the motor 3 to the controller 5. When the pulling operation on the trigger 24D is released, that is, when the stopping operation is performed (for example, when the operator releases the pulling operation by releasing the finger from the trigger 24D), the output of the tool start signal is stopped. Has been.

  The first connection portion 24B extends forward from the lower end portion of the grip portion 24A. A shaft 24E extending in the left-right direction is provided inside the front portion of the first connection portion 24B. The shaft 24E is inserted through the through hole of the inserted portion 23A. The handle housing 24 is configured to be rotatable about a shaft 24E. In addition, a battery mounting portion 24F to which the battery pack Q can be mounted is provided below the first connection portion 24B. The hammer drill 1 is configured to be driven by power supply from the battery pack Q mounted on the battery mounting portion 24F.

  The second connection portion 24C extends forward from the upper end portion of the grip portion 24A. The second connection portion 24C is provided with a vibration reduction mechanism 2B having an unillustrated elastic body, and the second connection portion 24C is connected to the connection portion 23B of the back cover 23 via the vibration reduction mechanism 2B. Even when the output portion 7 is vibrated in the front-rear direction, the handle housing 24 rotates about the shaft 24E, and the elastic body (not shown) of the vibration reduction mechanism 2B is expanded and contracted to absorb the vibration in the front-rear direction. Thus, it is possible to suppress the vibration in the front-rear direction from being transmitted to the operator who holds the holding portion 24A.

  The acceleration sensor support portion 25 is provided below the rear wall portion of the motor housing 21 and supports the acceleration sensor 8. As shown in FIGS. 6 and 7, the acceleration sensor support portion 25 is configured symmetrically. As shown in FIGS. 5 to 7, the acceleration sensor support portion 25 includes a housing wall portion 251, an elastic body 252, and a pressing portion 253 having a screw.

  As shown in FIG. 6, the housing wall 251 is substantially U-shaped when viewed from the rear, and protrudes rearward from the rear wall of the motor housing 21 as shown in FIG. 5.

  As shown in FIG. 5, the elastic body 252 is housed in the housing wall 251. The spring constant of the elastic body 252 is configured to be smaller than the left and right side walls of the housing wall portion 251.

  The acceleration sensor 8 is disposed in the accommodation wall portion 251 of the acceleration sensor support portion 25 and is configured to detect respective accelerations in a plurality of directions of the housing 2. As shown in FIG. 1, the acceleration sensor 8 is electrically connected to the control unit 5 via a conductor 8A and controls an acceleration signal corresponding to the detected direction and magnitude of the acceleration of the housing 2. The unit 5 can be output. In the present embodiment, the acceleration sensor 8 is configured to be able to independently detect at least accelerations in the front-rear direction and the rotational direction (left-right direction) of the housing 2. Further, the acceleration sensor 8 is located at a position away from the axis A of the tip tool P. More specifically, the acceleration sensor 8 is provided so that the position in the vertical direction overlaps the battery pack Q. Thereby, it is possible to appropriately detect the acceleration in the rotation direction (left-right direction) generated in the housing 2. The acceleration sensor 8 has a substrate 81 and a case 82. The acceleration sensor 8 is an example of the “detection unit” in the present invention.

  The case 82 is made of resin, and is configured symmetrically as shown in FIG. 5 and symmetrically as shown in FIG. The substrate 81 is disposed in the case 82. The substrate 81 has a flat plate shape extending in the vertical direction and the horizontal direction. Various elements for detecting the acceleration of the housing 2 are mounted on the rear surface of the substrate 81.

  As shown in FIG. 5, the case 82 is fixed to the housing 2 by the pressing portion 253 with the front and rear side surfaces thereof in contact with the elastic body 252. In addition, as shown in FIG. 6, the left and right side surfaces of the case 82 are in direct contact with the left and right side walls of the housing wall portion 251.

  Here, since the spring constant of the elastic body 252 is configured to be smaller than the left and right side walls of the accommodating wall portion 251, the acceleration sensor 8 has an allowable movement amount in the front-rear direction with respect to the housing 2 of the acceleration sensor 8. 2 is supported by the acceleration sensor support 25 so as to be larger than the allowable movement amount in the rotational direction with respect to 2. Accordingly, it is possible to appropriately detect the acceleration of the housing 2 in the rotational direction while suppressing the vibration of the housing 2 in the striking direction of the tip tool P.

  Next, the electrical configuration of the hammer drill 1 and the battery pack Q will be described with reference to FIG.

  As shown in FIG. 8, the battery pack Q accommodates a plurality of batteries serving as power sources for the motor 3, the control unit 5, and the like.

  The battery pack Q has a plus terminal and a minus terminal. When the battery pack Q is mounted on the battery mounting portion 24F of the handle housing 24, the positive terminal and the negative terminal of the battery pack Q are connected to predetermined terminals on the hammer drill 1 body side, respectively, and the voltage of the battery pack Q is set to the predetermined level. It is comprised so that it may apply between these terminals.

  The switching circuit 41 is an inverter circuit for supplying the electric power of the battery pack Q to the motor 3 and controlling the rotation of the motor 3, and is connected between the battery pack Q and the motor. The six switching members constituting the switching circuit 41 are connected in a three-phase bridge form, each gate is connected to the control unit 5, and each drain or each source is a coil U of the stator winding 33A of the motor 3. , V, W. The six switching members perform a switching operation for rotating the rotor 32 in a predetermined rotation direction based on a drive signal (gate signal) output from the control unit 5.

  The magnetic sensor unit 42 has three magnetic sensors. The three magnetic sensors are, for example, Hall elements. Each of the three magnetic sensors is configured to detect the magnetic field of the magnet 34 </ b> A fixed to the fan 34. When the magnetic field of the magnet 34 </ b> A is detected, each of the three magnetic sensors outputs a signal to the control unit 5. The magnetic sensor unit 42 is an example of the “detection unit” in the present invention.

  The acceleration sensor 8 has an acceleration detection circuit 80. The acceleration detection circuit 80 is a circuit that outputs a signal (acceleration signal) indicating the detected acceleration value (magnitude) in the front-rear direction and the rotation direction of the housing 2 to the control unit 5.

  The substrate 51 of the controller 5 includes a controller 51A, a control signal output circuit 51B, a rotor position detection circuit 51C, a temperature detection circuit 51D, a battery voltage detection circuit 51E, a current detection circuit 51F, a step-down circuit 51G, and a control system power supply circuit 51H. A communication circuit 51I, a battery temperature detection circuit 51J, and an overdischarge detection circuit 51K are mounted.

  The controller 51A stores a processing unit (not shown) having a central processing unit (CPU) that performs processing based on a processing program and various data used for controlling the motor 3, and the processing program, various data, various threshold values, and the like. (Not shown) and a control unit having a RAM (not shown) for temporarily storing data. The controller 51A controls the motor 3 according to the processing program.

  The controller 51 </ b> A performs rotational drive control as basic control for the motor 3. The rotation drive control is control for rotating the rotor 32 of the motor 3 in a predetermined rotation direction, and is performed by outputting a control signal to the control signal output circuit 51B. More specifically, the controller 51A forms a control signal for alternately switching the switching member to be conducted among the switching members based on the rotational position signal output from the rotor position detection circuit 51C, and the control signal Is output to the control signal output circuit 51B. In the rotational drive control, the controller 51A outputs a control signal for driving the switching member as a pulse width modulation signal (PWM) signal. The controller 51A is an example of the “control unit” in the present invention.

  In the present embodiment, the rotational speed [rpm] (in the following description, simply referred to as “rotational speed”) of the rotating shaft 31 of the motor 3 is a target rotational speed corresponding to each operation mode. Rotation drive control is performed while feedback control is performed so that the number becomes equal. More specifically, the controller 51A calculates the rotation speed of the rotating shaft 31 based on the rotation position signal output from the rotor position detection circuit 51C, compares the calculated rotation speed with the target rotation speed, and compares the comparison. Based on the result, constant rotation speed control is performed by repeatedly executing at high speed the process of changing the duty ratio of the PWM signal so that the rotation speed of the rotating shaft 31 becomes the target rotation speed.

  In the present embodiment, the rotational speed of the rotating shaft 31 of the motor 3 does not depend on the pressing amount of the trigger 24D. Since the number of rotations of the rotating shaft 31 of the motor 3 is controlled by the control unit 5 regardless of the pressing amount of the trigger 24D, it is possible to suitably perform work according to the operation mode.

  The control signal output circuit 51B is connected to the respective gates of the six switching members and the controller 51A. The control signal output circuit 51B is a circuit that outputs a drive signal to each gate of the six switching members based on the control signal output from the controller 51A.

  The rotor position detection circuit 51C is a circuit that detects the rotational position of the rotor 32 based on the signal output from the magnetic sensor unit 42, and outputs a signal indicating the detected rotational position (rotational position signal) to the controller 51A. . In the present embodiment, the rotational position of the rotary shaft 31 is detected by detecting the magnetic field of the magnet 34A attached to the fan 34 that rotates integrally with the rotary shaft 31. The rotation position may be directly detected.

  The temperature detection circuit 51D is a circuit for detecting the temperature of the switching circuit 41, and includes a temperature sensitive element such as a thermistor (not shown) provided in the vicinity of the switching circuit 41. The temperature detection circuit 51D is a circuit that outputs a signal (circuit temperature signal) indicating the detected temperature value to the controller 51A.

  The battery voltage detection circuit 51E is a circuit that detects the battery voltage of the battery pack Q and outputs a signal (battery voltage signal) indicating the value of the detected voltage to the controller 51A.

  The current detection circuit 51F detects the current (motor current) flowing in the motor 3 using the voltage drop value of the shunt resistor 50 provided between the switching circuit 41 and the battery pack Q, and the detected motor current This circuit outputs a signal indicating a value (current value signal) to the controller 51A.

  The step-down circuit 51G is a circuit that steps down a voltage (for example, 5V) input from the battery of the battery pack Q and outputs it to the control system power supply circuit 51H.

  The control system power supply circuit 51H is a constant voltage circuit for supplying a power supply voltage to the controller 51A. The control system power supply circuit 51H stabilizes the voltage (voltage after step-down) input from the step-down circuit 51G and supplies it to the controller 51A.

  The communication circuit 51I is a circuit that inputs and outputs battery identification information and tool identification information between the controller 51A and a microcomputer provided in the battery pack Q.

  The battery temperature detection circuit 51J is a circuit that detects the temperature of the battery of the battery pack Q and outputs a signal (battery temperature signal) indicating the detected temperature value to the controller 51A.

  The overdischarge detection circuit 51K is a circuit that can detect overdischarge of the battery pack Q and outputs a signal indicating overdischarge to the controller 51A when overdischarge is detected.

  Next, the operation mode switching work of the hammer drill 1 will be described with reference to FIGS. 1 and 4. In the present embodiment, as shown in FIG. 4, when the triangular mark 91 </ b> A formed on the operation unit 91 faces substantially rearward, the rotation hitting mode is selected. On the other hand, when the triangular mark 91 </ b> A formed on the operation unit 91 faces substantially forward, the hitting mode is selected.

  Specifically, as shown in FIG. 4, when the triangular mark 91 </ b> A formed on the operation portion 91 faces substantially rearward, the sleeve 92 shown in FIG. When the bevel gear of the sleeve 92 meshes with the bevel gear of the rotational force transmission mechanism 62, the output portion 7 (batter 71) is rotationally moved via the rotational force transmission mechanism 62, and the tip tool P is subjected to rotational force. Can be transmitted. In the present embodiment, at the same time, the striking force can be transmitted to the tip tool P by reciprocating the output portion 7 (striking element 71) via the power conversion mechanism 61. That is, it becomes a rotation impact mode in which the impact force and the rotational force can be transmitted to the tip tool P.

  When the triangular mark 91 </ b> A formed on the operation portion 91 faces substantially forward, the sleeve 92 moves rearward with respect to the cylinder 72, and the bevel gear of the sleeve 92 and the bevel gear of the rotational force transmission mechanism 62 are When the meshing is released, the transmission of the rotational force to the output unit 7 (cylinder 72) via the rotational force transmission mechanism 62 is interrupted. At this time, the output unit 7 is reciprocated via the power conversion mechanism 61 to be in a striking mode in which only the striking force can be transmitted to the tip tool P.

  Next, drive control of the motor 3 by the controller 51A of the control unit 5 will be described in detail along the flowchart shown in FIG. In addition, the graph shown in FIG. 10 is referred suitably.

  When the operator attaches the battery pack Q to the battery attachment portion 24F of the handle housing 24, power is supplied to the controller 51A (control portion 5), and the process shown in the flowchart of FIG.

  In step S101, the controller 51A determines whether or not a pulling operation is being performed on the trigger 24D. This determination is made based on whether or not a tool start signal is output from a switch mechanism (not shown).

  In step S101, when it is determined that the pull operation is not performed on the trigger 24D (step S101: NO), the controller 51A repeatedly performs the determination process of step S101. Note that at the start of the work (immediately after the pulling operation is performed on the trigger 24D), the motor 3 is not driven, and thus the process of step S107 is not executed. On the other hand, when it is determined in step S101 that the pulling operation is performed on the trigger 24D (step S101: YES), the controller 51A starts motor drive control (constant speed control) in step S102.

  Specifically, in step S102, the control signal output circuit 51B of the control unit 5 outputs a drive signal to each gate of each switching member of the switching circuit 41 based on the signal output from the controller 51A. The switching member starts a switching operation for rotating the rotor 32 in a predetermined rotation direction based on the drive signal output from the control signal output circuit 51B. As a result, the motor 3 is driven, and the driving force of the motor 3 is transmitted to the output unit via the power transmission unit 6, and the tip tool P starts to rotate and strike according to the operation mode selected by the operator.

  Next, the controller 51A determines whether or not the elapsed time from the start of driving of the motor 3 has exceeded the “predetermined time” (step S103). In the present embodiment, the predetermined time is 90 [ms] (indicated by time T [ms] in the graph of FIG. 10). In the present embodiment, 90 [ms] is determined in consideration of the time during which the operator presses the hammer drill 1 against the workpiece, and when the predetermined torque is applied, the clutch mechanism 63 rotates the torque of the motor 3. Sufficient time to shut off (activate). The predetermined time is an example of the “predetermined time” in the present invention. In the present embodiment, the predetermined time is 90 ms, but may be set between 50 ms and 200 ms (50 ms or more and less than 200 ms) based on characteristics of the clutch mechanism or the like.

  If it is determined in step S103 that 90 [ms] has not elapsed since the start of driving of the motor 3 (step S103: NO), the controller 51A determines whether or not the trigger 24D has been pulled (step S103: NO). Step S104). This determination is made based on whether or not a tool start signal is output from a switch mechanism (not shown) as in step S101 described above.

  In step S104, when it is determined that the pull operation is performed on the trigger 24D (step S104: YES), the controller 51A repeatedly performs the determination process of step S103. On the other hand, when it is determined in step S104 that the pull operation is not performed on the trigger 24D (step S104: NO), the controller 51A stops driving the motor 3 in step S107. Thereafter, the controller 51A repeatedly executes the processing from step S101 to step S104 as long as 90 [ms] has elapsed from the start of driving of the motor 3 as long as the trigger 24D is being pulled. That is, in the present embodiment, control (swing prevention control) for stopping the motor 3 is performed as long as the trigger 24D is operated until 90 [ms] has elapsed since the start of driving of the motor 3. Not performed. The control for repeatedly executing the processes in steps S101 to S104 is an example of the “second control” in the present invention.

  If it is determined in step S103 that 90 [ms] has elapsed since the start of driving of the motor 3 (step S103: YES), the controller 51A is based on the rotational position signal output from the rotor position detection circuit 51C. The number of rotations of the rotation shaft 31 of the motor 3 calculated as described above is compared with the “first threshold value” (step S105). In the present embodiment, the first threshold value is 5000 [rpm], and is indicated by X [rpm] in FIG. The first threshold is an example of the “first threshold” in the present invention.

  If it is determined in step S105 that the rotational speed of the rotary shaft 31 is greater than 5000 [rpm] (step S105: NO), the controller 51A continues the constant speed control of the motor 3, and thereafter the motor 3 stops. Up to the above, the processing of step S101 to step S106 is repeatedly executed. The control for repeatedly executing the processes in steps S101 to S106 is an example of the “first control” in the present invention.

  If it is determined in step S105 that the rotational speed of the rotating shaft 31 is smaller than 5000 [rpm] (step S105: YES), the controller 51A determines that kickback has occurred and stops the motor (step S105). S107). “The rotational speed of the rotating shaft 31 is smaller than 5000 [rpm]” is an example of the “first condition” in the present invention.

  Next, the effect of the hammer drill 1 according to the present embodiment will be described in detail with reference to FIGS. Note that (i) in FIG. 10 shows the relationship between the rotational speed of the rotating shaft 31 and the acceleration in the rotational direction generated in the housing 2 and the elapsed time from the start of driving of the motor 3 when kickback does not occur. ing. Further, (ii) shows that when the kickback occurs at the start of driving of the motor 3, the rotary shaft 31 of the rotary shaft 31 when the operator holding the hammer drill 1 main body is sufficiently pressed against the workpiece. The relationship between the rotational speed and the acceleration in the rotational direction generated in the housing 2 and the elapsed time from the start of driving of the motor 3 is shown. (Iii) is the rotation of the rotary shaft 31 when the operator holding the hammer drill 1 body is not sufficiently pressed against the workpiece by kicking back when the motor 3 starts to be driven. The relationship between the number and the acceleration in the rotational direction generated in the housing 2 and the elapsed time from the start of driving of the motor 3 is shown.

  As shown by the solid line (i) in FIG. 10A, when kickback does not occur, the rotational speed of the rotating shaft 31 of the motor 3 is set to the target rotational speed (in this embodiment, 20000). [rpm]) increases linearly. Specifically, as shown in FIG. 11A, the outer ring portion 63A of the clutch mechanism 63 that meshes with the pinion 31A provided on the rotating shaft 31 of the motor 3 rotates in the direction of arrow B. The clutch mechanism 63 and the rotational force transmission mechanism 62 rotate integrally through the engagement between the plurality of engaging portions 63F and the plurality of balls 63D, and the rotational force is transmitted.

  On the other hand, when kickback occurs at the start of driving of the motor 3, that is, when a load of a predetermined value or more is applied to the tip tool P (output unit 7) (in other words, the motor 3 exceeds a predetermined value). When the load is applied), as shown in FIG. 11B, the rotation of the rotational force transmission mechanism 62 and the inner ring portion 63B is restricted as the tip tool P is locked. In this state, the operator holding the hammer drill 1 main body is sufficiently pressed against the workpiece by the tip tool P, and the clutch mechanism 63 has a predetermined torque that can interrupt the transmission of the rotational force of the motor 3. When the mechanism 63 is applied, the protrusions of the plurality of engaging portions 63F of the outer ring portion 63A push the plurality of balls 63D inward in the radial direction of the inner ring portion 63B against the urging force of the plurality of springs 63C. The part 63A rotates in the arrow B direction relative to the inner ring part 63B. That is, the clutch mechanism 63 interrupts transmission of the rotational force of the motor 3. In the present embodiment, as indicated by a dotted line (ii) in FIG. 10B, the clutch is operated between 50 [ms] and 70 [ms], and the torque of the motor 3 is transmitted. It is configured to block.

  As described above, in the present embodiment, the control for stopping the motor 3 (prevention of swinging) is performed as long as the trigger 24D is operated until 90 [ms] has elapsed since the start of driving of the motor 3. Control). As a result, when a kickback occurs during an operation with a large load torque, the pressing force of the operator holding the hammer drill 1 main body against the work piece of the tip tool P is sufficient, and the clutch mechanism 63 is When a predetermined torque that can interrupt the transmission of the rotational force of the motor 3 is applied to the clutch mechanism 63, the clutch mechanism 63 interrupts the transmission of the rotational force of the motor 3 during a predetermined time (90 [ms]). Thus, it is possible to continue the operation without stopping the motor 3. Thereby, workability | operativity can be improved.

  On the other hand, when kickback occurs, that is, when a load of a predetermined value or more is applied to the tip tool P (output unit 7) (in other words, a load of a predetermined value or more is applied to the motor 3). In this case, the operator holding the hammer drill 1 main body is not sufficiently pressed against the workpiece by the tip tool P, and the clutch mechanism 63 generates a predetermined torque capable of interrupting transmission of the rotational force of the motor 3 to the clutch mechanism 63. If not, after 90 [ms] has elapsed since the start of driving of the motor, the actual rotational speed of the rotating shaft 31 and the rotational speed threshold value X [rpm] (5000 [rpm] in the present embodiment) are set. Compare. As shown in (iii) of FIG. 10A, when the actual rotational speed is smaller than 5000 [rpm], it is determined that kickback has occurred, and the motor 3 Stop driving.

  As described above, in the present embodiment, when the operator holding the hammer drill 1 main body is insufficiently pressed against the workpiece by the tip tool P and the predetermined torque is not applied to the clutch mechanism 63, the predetermined time is reached. (90 [ms]) After the lapse of time, the control of the control unit is switched from the second control (control to repeat step S101 to step S104) to the first control (control to repeat step S101 to step S106), and the drive of the motor 3 is stopped. be able to. Thereby, workability | operativity can be improved.

  In the present embodiment, the controller 51A determines the occurrence of kickback depending on whether the rotational speed of the rotating shaft 31 is less than 5000 [rpm] after 90 [ms] has elapsed. In this way, the rotation of the rotary shaft 31 is stopped according to the rotation speed (rotational speed) of the rotary shaft 31 that changes greatly when kickback occurs during drilling in the rotation / blow mode in which the rotational force is transmitted to the tip tool P. In order to prevent this, only the striking force is transmitted to the tip tool, and the hammering operation of the hammer drill 1 is carried out by the worker during the crushing (crushing) operation in the striking mode in which the change in the rotational speed of the rotary shaft 31 is small compared to the drilling operation Unexpected stoppage of the motor 3 due to the above is suppressed, and workability can be improved.

  In the present embodiment, the occurrence of kickback is determined based on whether or not the rotational speed of the rotary shaft 31 is below 5000 [rpm], but the rate of decrease in the rotational speed of the rotary shaft 31 is related to the rotational speed. The occurrence of kickback may be determined based on whether or not a predetermined threshold is exceeded.

  In the present embodiment, the threshold value X (5000 [rpm]) is set for the rotational speed of the rotating shaft 31, but a threshold value (for example, 2 [G]) for the acceleration in the rotational direction is set to actually set the housing. 2 may be configured to determine that kickback has occurred when the actual acceleration exceeds the threshold.

  Next, a hammer drill that is an example of an electric power tool according to a second embodiment of the present invention will be described with reference to FIG. The hammer drill according to the second embodiment has the same configuration as the hammer drill 1 according to the first embodiment. As shown in the flowchart of FIG. Unlike the hammer drill 1 according to the first embodiment, the same effects as in the first embodiment are obtained in other respects. Therefore, in the following description, when referring to the configuration, the description will be made using the same reference numerals as those in the first embodiment. In addition, the graph shown in FIG. 10 is referred suitably.

  Hereinafter, the drive control of the motor 3 by the controller 51A of the control unit 5 will be described in detail with reference to the flowchart shown in FIG. Since the processing from step S201 to step S204 is the same as the processing from step S101 to step S104 in the hammer drill 1 according to the first embodiment, the description thereof will be omitted and the processing after step S205 will be mainly described. . The control for repeating the processes from step S201 to step S204 corresponds to the “second control” in the present invention.

  In step S205, the controller 51A determines whether or not the magnitude of the rotational acceleration generated in the housing 2 exceeds the “second threshold”. In the present embodiment, the second threshold value is 2 [G], and is indicated by Y [G] in FIG. The second threshold only needs to be in an appropriate range for determining the occurrence of kickback, and may be a value larger or smaller than 2 [G], for example. The second threshold is an example of the “second threshold” in the present invention.

  In step S205, when it is determined that the magnitude of the acceleration generated in the housing 2 is smaller than 2 [G] (step S205: NO), the controller 51A continues the constant speed control of the motor 3.

  In step S205, when it is determined that the magnitude of the acceleration generated in the housing 2 is larger than 2 [G] (step S205: YES), the controller 51A continuously executes the process of step S206. “The magnitude of the acceleration generated in the housing 2 is larger than 2 [G]” is an example of the “second condition” in the present invention.

  In step S206, the controller 51A compares the rotation number of the rotation shaft 31 of the motor 3 calculated based on the rotation position signal output from the rotor position detection circuit 51C with the “first threshold value” (step S206). ). In the present embodiment, the first threshold value is 5000 [rpm], and is indicated by X [rpm] in FIG. The first threshold is an example of the “first threshold” in the present invention.

  If it is determined in step S206 that the rotational speed of the rotating shaft 31 is greater than 5000 [rpm] (step S206: No), the controller 51A continues the constant speed control of the motor 3, and thereafter the motor 3 stops. Until, the processing of step S201 to step S207 is repeatedly executed. The control for repeatedly executing the processes in steps S201 to S207 is an example of the “first control” in the present invention.

  If it is determined in step S206 that the rotation speed of the rotating shaft 31 is smaller than 5000 [rpm] (step S105: YES), the controller 51A determines that kickback has occurred and stops the motor (step S105). S208). “The rotational speed of the rotating shaft 31 is smaller than 5000 [rpm]” is an example of the “first condition” in the present invention.

  As described above, in the second embodiment, the controller 51A is generated in the housing 2 continuously from the start of the first control (control to repeat the processing of step S201 to step S207) to the stop of driving of the motor 3. It is determined whether or not the acceleration in the rotating direction is “the magnitude of the acceleration generated in the housing 2 is larger than 2 [G]”. When kickback occurs, generally, the rotational speed of the rotating shaft of the motor decreases after the acceleration in the rotational direction generated in the housing increases. According to such a configuration, the change in acceleration is controlled by the first control. Since monitoring is always performed from the start, the motor 3 can be stopped by preferably detecting kickback. Thereby, workability | operativity can be improved. Step S205 corresponds to the “first process” in the present invention.

  Further, after starting execution of step S205, the controller 51A continues until the motor 3 is stopped, and whether or not the rotational speed of the rotary shaft 31 is “the rotational speed of the rotary shaft 31 is smaller than 5000 [rpm]”. Is determined (step S206). As described above, when kickback occurs, the rotational speed generally decreases with an increase in acceleration. According to such a configuration, whether or not the condition regarding the acceleration in the rotational direction generated in the housing 2 is satisfied. Therefore, it is possible to effectively utilize the data storage area such as the RAM of the control unit 5. Step S206 corresponds to the “second process” in the present invention.

  Next, the effect of the hammer drill according to the present embodiment will be described with reference to FIG.

  As described above, in the present embodiment, when kickback occurs, that is, when a load of a predetermined value or more is applied to the tip tool P (output unit 7) (in other words, the motor 3 has a predetermined value or more). A predetermined torque that allows the clutch mechanism 63 to cut off the transmission of the rotational force of the motor 3 because the operator holding the hammer drill is not sufficiently pressed against the workpiece, and the clutch mechanism 63 can interrupt the transmission of the rotational force of the motor 3. In the case where the mechanism 63 is not applied, after 90 [ms] has elapsed since the start of driving of the motor, the rotational acceleration actually generated in the housing 2 and the acceleration threshold Y [G] (in this embodiment, 2 [ G]). When the actual acceleration is larger than 2 [G] as shown in (iii) of FIG. 10B, the actual rotational speed of the rotary shaft 31 and the rotational speed threshold value X [rpm] (this embodiment) In this embodiment, 5000 [rpm]) is compared. As shown in (iii) of FIG. 10A, when the actual rotational speed is smaller than 5000 [rpm], it is determined that kickback has occurred, and the motor 3 Stop driving.

  As described above, in the present embodiment, the drive of the motor 3 is stopped when the condition regarding the rotational speed generated in the housing 2 is satisfied at the same time as the condition regarding the rotational speed of the rotating shaft 31 is satisfied. Since it is comprised, the kickback which generate | occur | produces at the time of a drilling operation can be detected more accurately, and the drive of the motor 3 can be stopped. Thereby, workability | operativity can be improved.

  Further, by using the rotation speed flag and the acceleration flag indicating whether or not the respective conditions of the rotation speed and the acceleration are satisfied, a predetermined value (for example, “1”) is set in both the rotation speed flag and the acceleration flag. In this case, the motor may be configured to stop.

  In the present specification, the above embodiment has been described as an example, but the present invention can be modified in various ways within the scope of the claims in each component and each processing process of the above embodiment. It is understood by those skilled in the art.

DESCRIPTION OF SYMBOLS 1 ... Hammer drill 2 ... Housing 3 ... Motor 4 ... Inverter circuit board part 5 ... Control part 6 ... Power transmission part 7 ... Output part 8 ... Acceleration sensor 9 ... Operation mode switching part

Claims (9)

A housing;
A motor housed in the housing and having a rotating shaft;
An output unit that is driven by the motor and is attachable / detachable with a tip tool;
A clutch mechanism that is interposed between the motor and the output unit and is capable of transmitting the driving force of the motor to the output unit and interrupting transmission of the driving force when a load of a predetermined value or more is applied to the output unit. A power transmission unit having
A detection unit that detects at least one of the number of rotations of the rotation shaft and the acceleration generated in the housing;
When at least one of the first condition relating to the rotation speed detected by the detection unit and the second condition relating to the acceleration detected by the detection unit are satisfied in a state where the motor is driven Control of the motor between a first control for stopping the driving of the motor and a second control for continuing the driving of the motor even when at least one of the first condition and the second condition is satisfied. A switchable control unit,
The said control part switches the control of the said control part from said 2nd control to said 1st control after predetermined time progress from the drive start of a motor, The electric tool characterized by the above-mentioned.   The predetermined time is determined based on characteristics of the clutch mechanism, and is a time sufficient for the clutch mechanism to cut off transmission of the driving force when a load greater than the predetermined value is applied to the output unit. The power tool according to claim 1, wherein the power tool is provided.   The power tool according to claim 2, wherein the predetermined time is 50 ms or more and less than 200 ms. The power transmission unit can generate a striking force in the first direction on the tip tool by converting the rotational movement of the rotating shaft into a reciprocating motion in the first direction and striking the tip tool. In addition, by transmitting the rotational movement of the rotary shaft to the output unit, the tip tool can be configured to generate a rotational force in a second direction that intersects the first direction. The power transmission state can be switched between a first power transmission state in which force is transmitted while the rotational force is not transmitted and a second power transmission state in which at least the rotational force is transmitted to the tip tool,
The electric tool according to claim 2, wherein the clutch mechanism is provided on a transmission path of the rotational force. The first condition is that the rotational speed is smaller than a first threshold value related to the rotational speed,
The electric power tool according to claim 4, wherein the second condition is that the acceleration in the second direction generated in the housing is larger than a second threshold value.   6. The control unit according to claim 5, wherein when the first condition is satisfied after the predetermined time has elapsed, the control unit stops the motor regardless of whether the second condition is satisfied. The electric tool described.   The electric power tool according to claim 5, wherein the control unit stops the motor when the first condition is satisfied and the second condition is satisfied after the predetermined time has elapsed.   The control unit starts execution of a first process for determining whether the acceleration detected by the detection unit satisfies the second condition, and then the rotation number detected by the detection unit is the first number. The power tool according to claim 7, wherein a second process for determining whether or not one condition is satisfied is executed.   The power tool according to any one of claims 4 to 8, further comprising a switching operation unit that is manually operable and capable of mechanically switching the power transmission state of the power transmission unit.

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