JP2019098454A - Striking work machine - Google Patents

Abstract

To provide a striking work machine capable of improving workability by suitably detecting a kick-back caused in a striking work machine body.SOLUTION: A striking work machine comprises a housing 2, a motor 3 stored in the housing 2 and having a rotary shaft 31, an installation part 73 capable of attaching-detaching a tip tool P1, a power transmission part 6 capable of generating striking force in the longitudinal direction in the tip tool P1 by striking the tip tool P1 by converting rotary motion of the rotary shaft 31 into reciprocation in the longitudinal direction and constituted so that torque can be generated in the rotational direction for crossing with the longitudinal direction in the tip tool P1 by transmitting the rotary motion of the rotary shaft 31 to the installation part 73, an acceleration sensor 8 for detecting acceleration generated in the housing 2, and a controller 51A for stopping rotation of the rotary shaft 31 when satisfying a condition on a rotational speed of the rotary shaft 31 and satisfying a condition on the acceleration detected by the acceleration sensor 8.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a striking work machine.

  Hitherto, a striking operation in which a drill bit is formed in a workpiece (for example, concrete, steel, wood, etc.) by rotating a tip tool by driving a motor, or crushing is performed by applying a striking force to the tip tool The machine is widely known. As an example of such an impact working machine, as an operation mode, an impact mode for applying only an impact force to the tip tool to crush a workpiece, applying the above impact force to the tip tool, and rotating the tip tool There is known a hammer drill that can be mechanically switched to a rotation / impact mode for drilling a workpiece by transmitting a force and rotating a tip tool.

  In such a hammer drill, the tip tool may be caught on a hard part of the workpiece at the time of drilling operation in the rotation / strike mode and the tip tool may be locked, and the impact working machine body is largely shaken around by the drive of the tip tool. There is a possibility that back may occur and the workability may deteriorate.

  In order to cope with the kickback, conventionally, the acceleration and / or load current value generated in the striking work machine body is detected, and the kickback is performed when either the acceleration and / or load current value exceeds the threshold value. Control is performed to stop the rotation of the motor. For example, the hammer drill disclosed in Patent Document 1 includes an acceleration sensor that detects the acceleration of the hammer drill main body, and stops driving of the motor when the acceleration detected by the acceleration sensor exceeds a predetermined acceleration threshold. It is configured to let you

International Publication 2017/145643

  However, in the hammering (crushing) work of concrete in the striking mode, the operator himself swings around the striking work machine main body, so the acceleration sensor detects the acceleration caused by the swinging of the striking working machine main body by the worker himself, Although there was no kickback, there was a possibility that the drive of the motor would stop. In addition, in the flunging operation of concrete in the impact mode, the operation of pressing the tip tool against the workpiece and the operation of moving it away are repeated, so the load current fluctuates significantly, and It has been difficult to distinguish between variations and load current variations due to kickback during drilling operations in the spin and hit mode.

  Therefore, an object of the present invention is to provide a striking work machine capable of suitably detecting the kickback generated in the striking work machine main body and improving the workability.

  In order to solve the above problems, the present invention provides a housing, a motor having a rotary shaft housed in the housing, a mounting portion to which a tip tool can be attached and detached, and rotational movement of the rotary shaft in a first direction. It is possible to generate an impact force in the first direction on the tip tool by converting and striking the tip tool, and transmitting the rotational motion of the rotary shaft to the mounting portion to the tip tool. A power transmission unit configured to generate a rotational force in a second direction intersecting the first direction, an acceleration detection unit detecting an acceleration generated in the housing, and detecting the number of rotations of the rotation shaft A rotational speed detection unit and a first condition on the rotational speed detected by the rotational speed detection unit are satisfied, and a second condition on the acceleration detected by the acceleration detection unit is satisfied When it is, providing a striking working machine characterized by comprising a control unit for stopping the rotation of the rotary shaft.

  According to the impact working machine having the above configuration, the tip is stopped in order to stop the rotation of the rotary shaft according to the rotational speed of the rotary shaft of the motor, which largely changes at the time of kickback during drilling operation where rotational force is applied to the tip tool. The change in acceleration caused by the swinging motion of the striking work machine main body of the worker, etc., at the time of the lapping work where the change in rotational speed of the motor's rotary shaft is small compared to the drilling operation where only the striking force is applied to the tool. Unpredicted drive stop of the motor is suppressed, and workability is improved. Further, at the same time as satisfying the condition regarding the rotational speed of the rotating shaft, the rotation of the rotating shaft is stopped when the condition regarding the acceleration generated in the housing is satisfied. It is possible to detect the kickback that occurs and to stop the driving of the motor.

  In the above configuration, it is preferable that the first condition is a condition that the rate of decrease of the rotation speed of the rotation shaft exceeds a first threshold value regarding the rotation speed.

  According to such conditions, it is possible to accurately detect the kickback generated at the time of the drilling operation, and to preferably stop the motor.

  Further, it is preferable that the second condition is a condition that the acceleration in the second direction generated in the housing exceeds a second threshold.

  According to such conditions, it is possible to accurately detect the kickback generated at the time of the drilling operation, and to preferably stop the motor.

  The power transmission unit may transmit a first power transmission state in which the striking force is transmitted to the tip tool 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 power transmission state be switchable between them.

  According to such a configuration, although an acceleration corresponding to the power transmission state is generated in the housing, the motor that largely changes at the time of kickback at the time of drilling operation by the second power transmission state in which the rotational force is transmitted to the tip tool In order to stop the rotation of the rotation shaft according to the rotation speed of the rotation shaft, only the impact force is transmitted to the tip tool, and the first power transmission state according to the first power transmission state in which the change in the rotation speed of the rotation shaft of the motor is smaller than in drilling operation At the time of lapping work, an unexpected stop of the driving of the motor due to the change of the acceleration caused by the swing operation of the striking work machine main body of the worker is suppressed, and the workability is improved. Further, at the same time as satisfying the condition regarding the rotational speed of the rotating shaft, the rotation of the rotating shaft is stopped when the condition regarding the acceleration generated in the housing is satisfied. It is possible to detect the kickback that occurs and to stop the driving of the motor.

  The power transmission state of the power transmission unit may be mechanically operated between the first power transmission state and the second power transmission state according to the operation of the operation portion. It is preferable to further include a switchable switching mechanism.

  According to the above configuration, in order to stop the driving of the motor according to the rotational speed of the rotation shaft of the motor and the acceleration generated in the housing, when the power transmission state of the striking work machine is mechanically switched by the switching mechanism unit, It is not necessary to provide a sensor or the like for determining the power transmission state in the switching mechanism. That is, it is possible to detect the kickback generated at the time of the drilling operation in the second power transmission state without increasing the number of parts.

  Further, the mounting portion has a first portion which can not rotate in the second direction with respect to the housing, and a second portion which can rotate in the second direction with respect to the housing. The first tip tool having the engaging portion and the second tip tool having the second engaged portion are selectively configured to be detachably attachable as the tip tool, and the first portion is configured to receive the first engaged portion. A second engaging portion engageable with the second engaged portion, and the first tip tool is provided with a first engaging portion engageable with the portion; When mounted on the mounting portion, the first tip end tool can not rotate in the second direction with respect to the housing by the engagement of the first engaged portion and the first engaging portion. When the first power transmission state is established and the second tip tool is mounted to the mounting portion, the second engaged state And by the and the second engaging portion is engaged, it said that the second tool bit is rotatable second power transmitting state in the second direction relative to said housing preferred.

  According to the above configuration, the driving of the motor is stopped according to the rotational speed of the rotation shaft of the motor and the acceleration generated in the housing, so even in the case where the power transmission state is switched by selectively attaching and detaching the tip tool. It is possible to preferably detect the kickback that occurs at the time of the drilling operation in the second power transmission state.

  The acceleration detection unit is supported by the housing such that the movement allowance in the first direction with respect to the housing of the acceleration detection unit is larger than the movement allowance in the second direction with respect to the housing of the acceleration detection unit. Is preferred.

  According to such a configuration, the movement allowance of the acceleration detection unit with respect to the housing in the direction intersecting the striking direction of the tip tool is smaller than the movement allowance of the acceleration detection unit in the striking direction of the tip tool Therefore, it is possible to appropriately detect the acceleration of the housing in the rotation direction of the tip tool while suppressing the detection of the vibration of the housing in the striking direction of the tip tool.

  According to the striking work machine of the present invention, it is possible to suitably detect the kickback generated in the striking work machine main body and to improve the workability.

BRIEF DESCRIPTION OF THE DRAWINGS It is whole sectional drawing which shows the internal structure of the hammer drill concerning the 1st Embodiment of this invention. It is a top view of a hammer drill concerning a 1st embodiment of the present invention. It is III partial enlarged sectional view of FIG. 1, and the mode in 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 the IV-IV sectional view taken on the line of FIG. 3, and the mode in which the acceleration sensor support part of the hammer drill concerning 1st Embodiment of this invention supports an acceleration sensor is shown. It is an arrow V direction view of FIG. 1, and the mode in which the acceleration sensor support part of the hammer drill concerning the 1st Embodiment of this invention supports an acceleration sensor is shown. FIG. 1 is a circuit diagram showing an electrical configuration of a hammer drill according to a first embodiment of the present invention. It is a flow chart which shows operation of a hammer drill concerning a 1st embodiment of the present invention. (A) power supply current, (b) acceleration in the rotational direction generated in the housing, and (c) temporal change in the number of rotations of the rotor at the time of operation (fracturing) of hammer drill according to the first embodiment of the present invention Is a graph showing The graph which shows the time change of (a) power supply current at the time of the drilling operation of the hammer drill concerning the 1st Embodiment of this invention, (b) the acceleration of the rotation direction generate | occur | produced in a housing, and (c) the rotation speed of a rotor. It is. It is a whole sectional view showing the internal structure of the hammer drill concerning a 2nd embodiment of the present invention. It is a XI-XI line sectional view of Drawing 10, and the 1st tool attaching part of a hammer drill concerning a 2nd embodiment of the present invention is shown. It is a XII-XII line sectional view of Drawing 10, and the 2nd tool attaching part of a hammer drill concerning a 2nd embodiment of the present invention is shown. It is a figure which shows the front-end tool P2 which can be attached or detached to the mounting part of the hammer drill concerning the 2nd Embodiment of this invention, (a) is a rear elevation, (b) is a side view. It is a figure which shows the front-end tool P3 which can be attached or detached to the mounting part of the hammer drill concerning the 2nd Embodiment of this invention, (a) is a rear view, (b) is a side view.

  A hammer drill 1 which is an example of a striking work machine according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 9. The hammer drill 1 is a motorized striking work machine for forming a drilled hole in a material to be processed (for example, concrete, steel, wood, etc.) or crushing it by applying a striking force. The hammer drill 1 operates as an operation mode in which a tip tool P1 is rotated to pierce a workpiece, and a "rotation / impact mode" for striking the workpiece, and a strike mode in which the tip tool P1 strikes the workpiece "And.

  In the following description, "upper" shown in FIG. 1 is defined as upward, "down" as downward, "front" as front, and "rear" as rear. In addition, when the hammer drill is viewed from the rear, “right” is defined as the right direction, and “left” is defined as the left direction. When dimensions, numerical values, etc. are referred to in this specification, not only dimensions and numerical values that completely coincide with the dimensions, numerical values, etc., but also substantially identical dimensions, numerical values, etc. (for example, when within manufacturing error range Shall be included. Similarly, “substantially the same”, “substantially orthogonal”, “substantially parallel”, “substantially identical”, “identical”, “orthogonal”, “parallel”, “coincidence”, “uniform”, “constant”, etc. It is assumed that “substantially flush”, “substantially constant” and the like are included.

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

  As shown in FIG. 1, the housing 2 has 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 25. ing. The housing 2 is an example of the "housing" in the present invention.

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

  The motor 3 is a DC brushless motor, and has a rotating shaft 31, a rotor 32, a stator 33 and a fan 34.

  The rotating shaft 31 extends vertically and is rotatably supported by the housing 2. A pinion 31A that rotates integrally with the rotation shaft 31 is fixed to the upper end portion of the rotation shaft 31.

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

  The stator 33 is a stator having a stator winding 33A (FIG. 6) not shown. The stator 33 is fixed to the inner circumferential surface of the motor housing 21. The stator winding 33A also has star-connected three-phase coils U, V, W.

  The fan 34 is fixed to the rotating shaft 31 so as to be integrally rotatable with the rotating shaft 31 below the pinion 31A. A magnet 34A is fixed to the lower part of the fan 34.

  The inverter circuit board unit 4 is provided above the stator 33 of the motor 3. The inverter circuit board unit 4 has a board 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, etc. (See Figure 6).

  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, the gear housing 22 is attached with a side handle 2A which is gripped by an operator.

  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 bevel gear formed at the upper end, and converts the rotational movement of the rotation shaft 31 of the motor 3 into a reciprocating motion in the front-rear direction. By striking the tip tool P1, it is possible to generate an impact force in the back and forth direction in the tip tool P1, and by transmitting the rotational motion of the rotary shaft 31 to the output unit 7, the axis A of the tip tool P1. It is possible to generate a rotational force in the direction of rotation centering on. The power transmission unit 6 is configured to be able to change the drive state of the tip tool P1 by switching the power transmission state. Specifically, in the power transmission unit 6, the "impact mode" in which the impact force is transmitted to the tip tool P1 while the rotational force is not transmitted, and the "rotation / impact mode in which the impact force and the rotational force are transmitted to the tip tool And the power transmission state can be switched. It should be noted that the power transmission state is made between the “impact mode” in which the impact force is transmitted to the tip tool while the rotational force is not transmitted, and the “rotation mode” in which the rotational force is transmitted to the tip tool. It may be configured to be switchable. In the following description, the "rotational direction about the axis A" is simply referred to as "rotational 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 striking mode is an example of the “first power transmission state” in the present invention, and the rotation / impact mode is an example of the “second power transmission state” in the present invention.

  The output unit 7 is disposed above the rotational force transmission mechanism 62 in the gear housing 22 and driven by the motor 3. The output unit 7 includes a striker 71, a cylinder 72, and a mounting portion 73 to which the tip tool P1 can be attached and detached.

  The striker 71 is configured to be capable of reciprocating by the power conversion mechanism 61. Specifically, the front end of the striker 71 is configured to be able to abut on the rear end of the tip tool P1 mounted on the mounting portion 73, and along with the striker 71 reciprocating in the longitudinal direction, The striking force is transmitted to the

  The cylinder 72 is configured to be rotatable about an axis A extending in the front-rear direction by receiving the rotational force of the motor 3 via the rotational force transfer mechanism 62. Further, when the cylinder 72 is rotated, the mounting portion 73 is rotated, and the tip tool P1 mounted on the mounting portion 73 is configured to be rotatable around the axis A. The mounting portion 73 is an example of the “mounting portion” in the present invention.

  As shown in FIG. 1 and FIG. 2, the operation mode switching unit 9 is located at the top of the rear of the gear housing 22, and is configured to mechanically switch the power transmission state of the power transmission unit 6. . More specifically, the operation mode switching unit 9 transmits the rotational movement to the output unit 7 via the rotational force transmission mechanism 62 and the transmission of the rotational movement via the rotational force transmission mechanism 62 to the output unit 7. By switching between the shutoff state, it is possible to switch between the striking mode and the rotation / impact mode. Further, in the present embodiment, the transmission of the striking force to the tip tool P1 through the power conversion mechanism 61 at the time of operation is configured so as not to be blocked. As shown in FIGS. 1 and 2, the operation mode switching unit 9 has an operation unit 91 and a sleeve 92. The operation mode switching unit 9 is an example of the “switching mechanism unit” in the present invention.

  The operation unit 91 is a portion operated by the operator when switching the operation mode, and as shown in FIG. 2, has a substantially circular shape in top view. The operation unit 91 is configured to be rotatable. In the present embodiment, no magnetic sensor or the like for determining the state of operation unit 91 is provided, and control unit 5 determines the selected mode from the state of operation mode switching unit 9. It is configured to be disabled. The operation unit 91 is an example of the “operation unit” in the present invention.

  As shown in FIG. 1, the sleeve 92 has a substantially cylindrical shape extending in the front-rear direction. At the front end of the sleeve 92, a bevel gear capable of meshing with the bevel gear of the rotational force transmission mechanism 62 is formed. The inner diameter of the sleeve 92 is slightly larger than the outer diameter of the cylinder 72. The 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 sleeve 92 is configured to be integrally rotatable with the cylinder 72.

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

  The inserted portion 23A protrudes rearward at the lower side 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 extends in the front-rear direction at the upper end portion of the back cover 23.

  Further, the 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 substrate 51, and various circuits and the like for controlling the hammer drill 1 are mounted on the substrate (see FIG. 6).

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

  The gripping portion 24A is a portion gripped by a worker at the time of operation, 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 front upper portion of the grip portion 24A. A switch mechanism (not shown) connected to the control unit 5 is provided inside the grip 24A. The switch mechanism controls the tool start signal for starting the motor 3 when the trigger 24D is pulled or started (for example, when pushed by the operator's finger into the handle housing 24). Output, and is configured to stop the output of the tool start signal when the pulling operation on the trigger 24D is released or stopped (for example, when the operator releases the pulling operation from the trigger 24D). There is.

  The first connection portion 24B extends forward from the lower end portion of the grip portion 24A. Inside the front portion of the first connection portion 24B, a shaft 24E extending in the left-right direction is provided. The shaft 24E is inserted through the through hole of the insertion portion 23A. The handle housing 24 is configured to be rotatable about a shaft 24E. In addition, a battery mounting portion 24F capable of mounting the battery pack Q is provided below the first connection portion 24B. The hammer drill 1 is configured to be drivable by power supply from a battery pack Q mounted to 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 elastic body (not shown), 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 vibration in the direction of the axis A occurs in the output unit 7, the handle housing 24 pivots about the shaft 24E, and the elastic body (not shown) of the vibration reduction mechanism 2B expands and contracts to vibrate in the direction of the axis A. Is absorbed, and transmission of vibration in the direction of the axis A to the worker gripping the grip 24A is reduced.

  The acceleration sensor support 25 is provided on the lower part of the rear wall of the motor housing 21 and supports the acceleration sensor 8. As shown in FIG. 4 and FIG. 5, the acceleration sensor support 25 is configured to be symmetrical in left and right. As shown in FIGS. 3 to 5, 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. 4, the housing wall 251 is substantially U-shaped in a rear view, and protrudes rearward from the rear wall of the motor housing 21 as shown in FIG. 3.

  As shown in FIG. 3, the elastic body 252 is housed in the housing wall 251. The spring constant of the elastic body 252 is smaller than the left and right side walls of the housing wall 251. The elastic body 252 is an example of the "buffer member" in the present invention.

  The acceleration sensor 8 is disposed in the housing wall 251 of the acceleration sensor support 25 and is configured to be able to detect the acceleration in each of the 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 the lead 8A, and controls an acceleration signal according to the detected direction and magnitude of the acceleration of the housing 2. The unit 5 is configured to be able to output. The acceleration sensor 8 is configured to be capable of independently detecting at least acceleration in the front-rear direction and the rotational direction (left-right direction) of the housing 2. Further, in the present embodiment, the acceleration sensor 8 is located at a position separated from the axis A of the tip tool P1. 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 rotational direction (left and 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 "acceleration detection unit" in the present invention.

  The case 82 is made of resin and is symmetrical in the front-rear direction as shown in FIG. 3 and in the left-right symmetry as shown in FIG. The substrate 81 is disposed in the case 82. The substrate 81 is in the form of a flat plate extending in the vertical and horizontal directions. On the rear surface of the substrate 81, various elements for detecting the acceleration of the housing 2 are mounted.

  As shown in FIG. 3, the case 82 is fixed to the housing 2 by the pressing portion 253 in a state in which the front and rear side surfaces are in contact with the elastic body 252. Further, as shown in FIG. 4, the left and right side surfaces of the case 82 are in direct contact with the left and right side walls of the accommodation wall 251.

  Here, since the spring constant of the elastic body 252 is smaller than the left and right side walls of the housing wall 251, the acceleration sensor 8 has an allowance for movement of the acceleration sensor 8 in the front-rear direction relative to the housing 2 of the acceleration sensor 8. It is supported by the acceleration sensor support portion 25 so as to be larger than the movement allowance in the rotational direction about the axis A with respect to the angle 2. Thereby, it is possible to appropriately detect the acceleration of the housing 2 in the rotational direction of the tip tool P1 while suppressing the detection of the vibration of the housing 2 in the striking direction of the tip tool P1.

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

  As shown in FIG. 6, the battery pack Q accommodates a plurality of batteries serving as a power source of 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 plus terminal and the minus terminal of the battery pack Q are respectively connected to the predetermined terminals on the hammer drill 1 main body side, and the voltage of the battery pack Q is the predetermined voltage. It is comprised so that it may be applied between the terminals of.

  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 3. The six switching members constituting the switching circuit 41 are connected in a three-phase bridge type, 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 are connected. The six switching members perform a switching operation of rotating the rotor 32 in a predetermined rotation direction based on the 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 34A fixed to the fan 34. When the magnetic field of the magnet 34A is detected, each of the three magnetic sensors outputs a signal to the control unit 5.

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

  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 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 program (not shown) having a central processing unit (CPU) that performs calculations based on various programs and a processing program used to control the motor 3, the processing program, various data, various threshold values, etc. And a storage unit having a RAM (not shown) for temporarily storing data. The controller 51A controls the motor 3 in accordance with the processing program.

  In addition, the controller 51A performs rotational drive control as basic control on the motor 3. The rotational drive control is control for rotationally driving the rotor 32 of the motor 3 in a predetermined rotational 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 of the switching members to be conductive 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.

  Further, in the present embodiment, the target [rotation speed per unit time [rpm] (in the following description, simply referred to as "rotation speed") of the rotation shaft 31 (motor 3) is a target according to each operation mode Rotational drive control is performed while performing feedback control so that the rotational speed is achieved. More specifically, the controller 51A calculates the number of rotations of the rotary shaft 31 based on the rotation position signal output from the rotor position detection circuit 51C, compares the calculated number of rotations with the target number of rotations, Based on the result, the constant rotation number control is performed by repeatedly and repeatedly executing the process of changing the duty ratio of the PWM signal so that the rotation number of the rotation shaft 31 becomes the target rotation number.

  Further, in the present embodiment, the number of rotations of the rotation shaft 31 of the motor 3 does not depend on the pressing amount of the trigger 24D. Since the number of rotations of the rotation 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 the operation according to the operation mode.

  The control signal output circuit 51B is connected to the 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 the gates 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 (rotational position signal) indicating the detected rotational position 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. It may be configured to directly detect the rotational position of.

  The temperature detection circuit 51D is a circuit for detecting the temperature of the switching circuit 41, and includes a temperature sensing element such as a thermistor (not shown) provided near the switching circuit 41. The temperature detection circuit 51D is a circuit that outputs a signal (circuit temperature signal) indicating the value of the detected temperature 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 through 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 detects the detected motor current. It is a circuit which outputs a signal (current value signal) indicating a value to the controller 51A.

  The step-down circuit 51G is a circuit that steps down (for example, 5 V) the voltage (for example, 14.4 V) input from the battery of the battery pack Q and outputs the voltage 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 voltage reduction) input from the voltage reduction 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 value of the detected temperature 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 operation of the hammer drill 1 will be described with reference to FIGS. 1 and 2.

  When switching the operation mode, the operator rotates the operation unit 91. In the present embodiment, as shown in FIG. 2, when the triangular mark 91A formed on the operation unit 91 is directed substantially backward, the rotation / strike mode is selected. On the other hand, when the triangular mark 91A formed on the operation unit 91 is substantially forward, the striking mode is selected.

  Specifically, as shown in FIG. 2, when the triangular mark 91 </ b> A formed on the operation portion 91 faces substantially backward, the sleeve 92 shown in FIG. The bevel gear of the sleeve 92 meshes with the bevel gear of the rotational force transmission mechanism 62, whereby the output unit 7 (cylinder 72) is rotationally moved via the rotational force transmission mechanism 62 and rotational force is applied to the tip tool P1. It becomes possible to transmit. In the present embodiment, at the same time, the impact force can be transmitted to the tip tool P by reciprocating the output unit 7 (the striker 71) via the power conversion mechanism 61. That is, it becomes rotation / striking mode which can transmit striking force and rotational force to tip tool P. FIG.

  Further, when the triangular mark 91A 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 By releasing the meshing, the transmission of the rotational force to the output unit 7 (the cylinder 72) via the rotational force transmission mechanism 62 is blocked. At this time, the output unit 7 is reciprocated via the power conversion mechanism 61 to be in the striking mode in which only the striking force can be transmitted to the tip tool P1.

  Next, processing for detecting a kickback that occurs during a drilling operation using the rotation / strike mode by the controller 51A of the control unit 5 will be described along the flowchart shown in FIG.

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

  In step S101, the controller 51A determines whether a pull operation is performed on the trigger 24D. The said judgment is judged by whether the tool starting signal is output from the switch mechanism which is not shown in figure.

  When it is determined in step S101 that a pulling operation is not performed on the trigger 24D (step S101: No), the controller 51A repeatedly performs the determination process of step S101. In addition, since the motor 3 is not driven at the time of an operation | work start, the process of step S110 is not performed. On the other hand, when it is determined that the pulling operation is performed on the trigger 24D in step S101 (step S101: Yes), the controller 51A starts the drive control (constant speed control) of the motor in step S102.

  Specifically, in step S102, the control signal output circuit 51B outputs a drive signal to each gate of the switching member of the switching circuit 41 based on the signal output from the controller 51A. The switching member starts the switching operation of rotating the rotor 32 in a predetermined rotation direction based on the drive signal output from the control unit 5. Thereby, the motor 3 is driven, the driving force of the motor 3 is transmitted to the output unit 7 through 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 detects the number of rotations of the rotation shaft 31 and the acceleration in the rotation direction of the housing 2 (step S103). Specifically, the controller 51A calculates the number of rotations of the rotation shaft 31 based on the rotation position signal output from the rotor position detection circuit 51C. The acceleration sensor 8 also detects the acceleration generated in the housing 2 and outputs an acceleration signal indicating the value (magnitude) of the detected acceleration to the controller 51A. The rotor position detection circuit and the controller 51A are examples of the "rotational speed detection unit" in the present invention.

  Next, the controller 51A determines whether the difference between the number of rotations of the rotary shaft 31 detected in step S103 and the number of rotations of the rotary shaft 31 before a predetermined time exceeds a first threshold (step S104). . In other words, the controller 51A determines whether the rate of decrease of the rotational speed of the rotating shaft 31 exceeds a first threshold value regarding the rotational speed. In the present embodiment, the predetermined time is “20 ms”, and the first threshold is “1500 [rpm]”. The predetermined time and the first threshold may be in the appropriate range to determine the occurrence of kickback, and for example, the predetermined time may be shorter or longer than 20 ms. The first threshold is an example of the “first threshold” in the present invention. Further, “whether or not the difference between the number of rotations of the rotor 32 and the number of rotations of the rotor 32 before the predetermined time exceeds a first threshold” is an example of the “first condition” in the present invention.

  When it is determined that the difference between the rotational speed of the rotary shaft 31 detected in step S104 and the rotational speed of the rotary shaft 31 20 ms before exceeds 1500 [rpm] (step S104: Yes), the controller 51A performs the process in step S105. Execute the rotation number flag processing. Here, the rotational speed flag is formed of one bit (binary) indicating whether the difference between the rotational speed of the rotary shaft 31 and the rotational speed of the rotary shaft 31 20 ms before exceeds 1500 [rpm] It is a flag. In the present embodiment, when controller 51A determines that the difference between the number of rotations of rotation shaft 31 and the number of rotations of rotation shaft 31 20 ms before exceeds 1500 [rpm] (step S104: Yes), in step S105. "1" is set. In the present embodiment, "0" is set as the initial value of the rotation number flag. Further, in the present embodiment, when “1” is once set as the rotation speed flag in step S105, the state in which “1” is set is maintained for 100 ms, and after 100 ms has elapsed It is configured to be initialized to "0". In addition, since the rotation speed of the rotating shaft 31 before predetermined time does not exist at the time of a work start, it is comprised so that step S105 may be performed after the said predetermined time progress.

  After performing the number-of-rotations flag process in step S105, or in any case where it is determined in step S104 that the difference between the number of rotations of rotor 32 and the number of rotations of rotor 32 20 ms before does not exceed the first threshold. In step S106, the controller 51A determines whether the magnitude of the acceleration in the rotational direction generated in the housing 2 exceeds the second threshold. In the present embodiment, the second threshold is “4 [G]”. The second threshold may be in a suitable range for determining the occurrence of kickback, and may be, for example, a value larger or smaller than 4G. The second threshold is an example of the “second threshold” in the present invention. In addition, “whether or not the magnitude of the acceleration in the rotational direction generated in the housing 2 exceeds the second threshold” is an example of the “second condition” in the present invention.

  When it is determined in step S105 that the magnitude of the acceleration in the rotational direction generated in the housing 2 exceeds 4 [G] (step S106: Yes), the controller 51A performs acceleration flag processing in step S107. . Here, the acceleration flag is a flag composed of one bit (two values) indicating whether or not the magnitude of the acceleration in the rotational direction generated in the housing 2 exceeds 4 [G]. In the present embodiment, when the controller 51A determines that the acceleration in the rotational direction of the housing 2 exceeds 4 [G] (step S106: Yes), “1” is set in step S107. In the present embodiment, “0” is set as the initial value of the acceleration flag. Further, in the present embodiment, when “1” is once set as the acceleration flag in step S107, the state in which “1” is set is maintained for 100 ms, and “0 It is configured to be initialized to

  After performing the acceleration flag processing in step S107, or in the case where it is determined that the acceleration in the rotational direction generated in the housing 2 does not exceed the second threshold in step S106, the controller 51A performs the process in step S108. It is determined whether "1" is set in any of the rotation number flag and the acceleration flag.

  If it is determined that "1" is set in both the rotation number flag and the acceleration flag (step S108: Yes), the controller 51A determines that kickback is occurring and stops the motor (step S109). ).

  On the other hand, when it is determined that "1" is not set in at least one of the rotation number flag and the acceleration flag (step S108: No), the state of the trigger 24D is monitored thereafter (step S101). Are repeatedly performed (steps S103 to S108). When the pulling operation of the trigger 24D is released (step S101: No), the driving of the motor is stopped (step S110).

  As described above, when the control unit 5 satisfies both the condition related to the rotational speed of the rotary shaft 31 detected by the rotor position detection circuit 51C and the controller 51A and the condition related to the acceleration detected by the acceleration sensor 8 Stop the rotation of the rotary shaft 31. That is, in order to stop the rotation of the rotary shaft 31 according to the rotational speed of the rotary shaft 31 of the motor 3 which largely changes at the time of kicking back at the time of drilling operation where rotational force is added to the front end tool P1, the tip tool P1 is hit. An unexpected motor due to the change in acceleration caused by the swinging movement of the hammer drill main body, etc. at the time of operation with a small amount of change in the rotational speed of the rotary shaft 31 of the motor 3 with a small force. The driving stop of 3 is suppressed and the workability is improved. Further, at the same time as satisfying the condition related to the rotational speed of the rotating shaft 31, the rotation of the rotating shaft 31 is stopped when the condition related to the acceleration generated in the housing 2 is satisfied. It becomes possible to detect the kickback which occurs at the time of drilling operation, and to stop the driving of the motor 3.

  Next, the effects of the hammer drill 1 according to the present embodiment will be described with reference to the graphs shown in FIGS. 8 and 9.

  Conventionally, at the time of drilling operation in the rotation and impact mode (rotation mode) using a hammer drill, the tip tool may be caught on a hard part of the workpiece and the tip tool may be locked. There is a possibility that the kickback which is thrown around may occur and the workability may deteriorate. Therefore, a striking work machine that accurately detects kickback has been desired.

  Here, as shown in FIG. 8 (a), in the hammering (crushing) operation of concrete in the striking mode, the operation of pressing the tip tool against the workpiece and the operation of separating it are repeatedly performed. Therefore, the fluctuation of the current value is severe, and the fluctuation of the current value at the time of the relevant rowing work and the fluctuation of the current value caused by the kickback at the time of drilling operation in the rotation / striking mode (rotation mode) (FIG. 9A). It was difficult to identify. That is, it was difficult to detect the occurrence of kickback from the power supply current value.

  In addition, when only acceleration generated in the housing is used as a reference for determining the occurrence of kickback, the acceleration sensor is used because the worker himself swings around the hammer drill main body in the operation of removing concrete in the striking mode. The acceleration caused by the swinging of the hammer drill main body by the operator himself is detected, and although the kickback does not occur, the driving of the motor is stopped, which may deteriorate the workability. Further, as shown in FIGS. 8 (b) and 9 (b), the value of acceleration in the rotational direction generated in the housing fluctuates even during normal operation in which no kickback occurs, so It was difficult to detect the occurrence of kickback on the basis of acceleration alone.

  Although it is conceivable to provide means (a magnetic sensor or the like) for determining the state of the operation mode switching unit, the number of parts may be increased.

  However, in the present embodiment, the occurrence of kickback is determined based on the rotational speed of the rotating shaft 31. As shown in FIGS. 8 (c) and 9 (c), regardless of whether it is a frying operation or a drilling operation, the number of rotations of the rotating shaft 31 at the time of normal operation in which no kickback occurs Fluctuation is small. That is, in the present embodiment, the rotation of the rotary shaft 31 is stopped according to the rotational speed of the rotary shaft 31 of the motor 3 which changes largely only when kickback occurs during drilling operation where rotational force is applied to the tip tool P1. In order to reduce the change in the rotational speed of the rotary shaft 31 of the motor 3 with a small change in the rotational speed of the motor 3 compared to the drilling operation, only the striking force is added to the tip tool P1. Unpredicted motor drive stoppage due to changes in acceleration is suppressed, and workability is improved.

  Further, as shown in FIG. 9B, when the kickback occurs, the acceleration in the rotational direction of the housing 2 largely fluctuates. In the present embodiment, the condition regarding the rotational speed of the rotary shaft 31 Because the rotation shaft 31 is configured to stop the rotation when the conditions relating to the acceleration generated in the housing 2 are satisfied at the same time, the kickback generated at the time of the drilling operation is detected more accurately, It becomes possible to stop the drive of the motor.

  In addition, since the kickback is detected using an acceleration sensor, a rotational position detection circuit, and the like that are conventionally provided in hammer drills in general, it is possible to suppress an increase in the number of parts.

  Next, a hammer drill 10 which is an example of a striking work machine according to a second embodiment of the present invention will be described with reference to FIGS. 10 to 14. The hammer drill 10 basically has the same configuration as the hammer drill 1 according to the first embodiment, and the description of the same configuration as that of the hammer drill 1 is appropriately omitted, and the different configurations are mainly described. Do. Further, the hammer drill 10 has an electrical configuration similar to that of the hammer drill 1 and performs processing for determining kickback in accordance with the flowchart shown in FIG. 7. In the present embodiment, the configuration corresponding to the operation mode switching unit 9 of the hammer drill 1 according to the first embodiment is not provided.

  As shown in FIG. 7, in the hammer drill 100 according to the second embodiment, an output unit 17 is provided instead of the output unit 7. Further, a gear housing 122 is provided in place of the gear housing 22.

  The output unit 17 includes a striker 171, a cylinder 172, and a mounting unit 173.

  The striker 171 is configured to be capable of reciprocating by the power conversion mechanism 61 of the power transmission unit 6. Specifically, the front end of the striker 171 is configured to be able to abut on the rear end of the tip tool attached to the attachment portion 173, and the striker 171 strikes the tip tool as it reciprocates back and forth. Power is transmitted.

  The cylinder 172 is configured to be rotatable about an axis A extending in the front-rear direction by receiving the rotational force of the motor 3 via the rotational force transmission mechanism 62 of the power transmission unit 6.

  The mounting portion 173 has a first tool holding portion 173A and a second tool holding portion 173B. The mounting portion 173 is an example of the “mounting portion” in the present invention.

  As shown in FIG. 11, the first tool holder 173A is fixed to the gear housing 22 by a fixing member 122A. Thereby, the first tool holding portion 173A is configured to be non-rotatable relative to the housing 2. Further, as shown in FIGS. 10 and 11, the first tool holding portion 173A has a first engaging portion 173C which is a front portion thereof. The first tool holding portion 173A is an example of the "first portion" in the present invention. The first engagement portion 173C is an example of the “first engagement portion” in the present invention.

  As shown in FIGS. 10 and 11, the first engaging portion 173C is formed with an insertion hole 173a formed in a substantially regular hexagonal column shape and extending in the front-rear direction.

  The second tool holding portion 173B is configured to be rotatable integrally with the cylinder 172. In other words, the second tool holder 173 B is configured to be rotatable relative to the housing 2. As shown in FIG. 10 and FIG. 12, the second tool holding portion 173B has a second engaging portion 173D which is a front portion thereof. The second tool holding portion 173B is an example of the “second portion” in the present invention. The second engagement portion 173D is an example of the “second engagement portion” in the present invention.

  As shown in FIGS. 10 and 12, the second engagement portion 173D is formed with an insertion hole 173b which is formed in a substantially regular hexagonal column shape and extends in the front-rear direction.

  Next, with reference to FIG. 13 and FIG. 14, the configurations of the tip tool P2 and the tip tool P3 selectively attachable to and detachable from the mounting portion 173 will be described. The direction will be described based on the state in which the end tool P2 and the end tool P3 are attached to the hammer drill 10. The tip tool P2 is an example of the "first tip tool" in the present invention. The tip tool P3 is an example of the "second tip tool" in the present invention.

  As shown in FIG. 13, the tip tool P2 has a bit portion P21, an engaged portion P22, an extension portion P23, and a restricting portion P24.

  The bit portion P21 has a substantially cylindrical shape extending in the front-rear direction. The front end of the bit portion P21 is formed to be pointed forward as it goes forward.

  As shown in FIG. 13, the engaged portion P <b> 22 is formed in a substantially regular hexagonal prism shape extending in the front-rear direction. The engaged portion P22 is formed to be slightly smaller than the insertion hole 173a formed in the substantially regular hexagonal column shape of the first engaging portion 173C. That is, the distance from the axis A to each surface of the engaged portion P22 is slightly shorter than the distance from the axis A to each surface forming the insertion hole 173a. Thereby, the first engagement portion 173C and the engaged portion P22 can be engaged. Further, the tip tool P2 is configured so as to be incapable of relative rotation with respect to the housing 2 by the engagement of the first engagement portion 173C that is not relatively rotatable with respect to the housing 2 and the engaged portion P22. There is. The engaged portion P22 is an example of the "first engaged portion" in the present invention.

  As shown in FIG. 13, the extending portion P23 is formed in a substantially cylindrical shape extending in the front-rear direction. As shown in FIG. 13A, the radius of the extending portion P23 is shorter than the distance from the axis A to each surface of the engaged portion P22. Further, the radius of the extension portion P23 is shorter than the distance from the axis line A to each surface forming the insertion hole 173b of the second engagement portion 173D.

  The restricting portion P24 is formed in a substantially disc shape slightly extending in the front-rear direction, and provided at the front end of the engaged portion P22. As shown in FIG. 13A, the radius of the restricting portion P24 is longer than the distance from the axis A to each surface of the engaged portion P22.

  As shown in FIG. 14, the tip tool P3 has a bit portion P31, an engaged portion P32, an extension portion P33, and a restricting portion P34.

  The bit portion P31 has a substantially cylindrical shape extending in the front-rear direction. The front end of the bit portion P31 is formed to be pointed forward as it goes forward. Further, on the circumferential surface of the bit portion P31, a spiral rib is provided so as to extend in the axial direction of the tip tool P3.

  As shown in FIG. 14, the engaged portion P32 has a substantially regular hexagonal prism shape extending in the front-rear direction. The engaged portion P32 is formed slightly smaller than the insertion hole 173b formed in the substantially regular hexagonal column shape of the second engagement portion 173D. That is, the distance from the axis A to each surface of the engaged portion P32 is slightly shorter than the distance from the axis A to each surface forming the insertion hole 173b. Thereby, the second engaging portion 173D and the engaged portion P32 can be engaged. In addition, the tip tool P3 is configured to be able to rotate relative to the housing 2 by engaging the second engaging portion 173D that is rotatable relative to the housing 2 and the engaged portion P32. There is. The engaged portion P32 is an example of the “second engaged portion” in the present invention.

  As shown in FIG. 14, the extension P33 is formed in a substantially cylindrical shape extending in the front-rear direction. As shown in FIG. 13A, the radius of the extension P33 is shorter than the distance from the axis A to each surface of the engaged portion P32. The radius of the extension P33 is shorter than the distance from the axis A to each surface of the first engagement portion 173C forming the insertion hole 173a.

  The restriction portion P34 is formed in a substantially disc shape that slightly extends in the front-rear direction, and is provided at the front end of the extension portion P33. As shown in FIG. 14A, the radius of the restricting portion P34 is larger than the radius of the extending portion P33. Although not shown in the figure, the radius of the restricting portion P34 is longer than the distance from the axis A to each surface forming the insertion hole 173a of the first engaging portion 173C.

  Next, the switching operation of the operation mode of the hammer drill 10 will be described.

  In the present embodiment, the configuration corresponding to the operation mode switching unit 9 of the hammer drill 1 in the first embodiment is not provided, and the operation is achieved by selectively attaching and detaching the end tool P2 and the end tool P3. Switch the mode.

  More specifically, when the worker performs a frying operation, the tip tool P2 is brought closer to the insertion hole 173a of the first engagement portion 173C of the first tool holding portion from the side of the extension portion P23 and is inserted . At this time, the tip tool P2 is positioned with respect to the housing 2 by bringing the rear surface of the restriction portion P24 of the tip tool P2 into contact with the front surface of the first engagement portion 173C. In this state, the engaged portion P22 of the tip tool P2 is positioned substantially at the same position as the insertion hole 173a of the first engagement portion 173C in the front-rear direction, and the extension portion P23 is the insertion hole 173b of the second engagement portion 173D. And approximately at the same position in the front-rear direction.

  In this state, the first engaging portion 173C and the engaged portion P22 which can not relatively rotate with respect to the housing 2 are engaged, and the radius of the extending portion P23 is from the axis A to each surface of the engaged portion P22 Since it is configured shorter than the distance to the end, the rotational force is not transmitted to the tip tool P2. On the other hand, the striking force is transmitted to the tip tool P2 as the striker 171 reciprocates in the front-rear direction. At this time, the movement in the striking direction of the tip tool P2 is guided by the inner peripheral surface of the first engaging portion 173C forming the insertion hole 173a. That is, when the tip tool P2 is mounted on the mounting portion 173, the tip tool P2 rotates in the rotational direction with respect to the housing 2 by the engagement of the engaged portion P22 and the first engagement portion 173C. It becomes impossible striking mode.

  In addition, when the worker performs a drilling operation, the tip tool P3 is brought close to the insertion hole 173b of the first engaging portion 173C of the first tool holding portion from the engaged portion P32 side and inserted. At this time, the tip tool P3 is positioned with respect to the housing 2 by bringing the rear surface of the restriction portion P34 of the tip tool P3 into contact with the front surface of the first engagement portion 173C. In this state, the engaged portion P32 of the tip tool P3 is substantially at the same position as the insertion hole 173b of the second engagement portion 173D in the front-rear direction, and the extension portion P33 is the insertion hole 173a of the first engagement portion 173C. And approximately at the same position in the front-rear direction.

  In this state, the second engaging portion 173D and the engaged portion P32 which can rotate relative to the housing 2 are engaged with each other, and the radius of the extending portion P33 is inserted from the axis A into the first engaging portion 173C. Because the distance to each surface forming the hole 173a is shorter than the distance, the rotational force is transmitted to the tip tool P3. Further, as the striker 171 reciprocates in the front-rear direction, an impacting force is transmitted to the tip tool P3. At this time, the movement in the striking direction of the tip tool P3 is guided by the inner peripheral surface of the second engaging portion 173D which forms the insertion hole 173b. That is, when the tip tool P3 is attached to the attachment portion 173, the tip tool P3 can be rotated relative to the housing 2 by engagement between the engaged portion P32 and the second engagement portion 173D. It becomes hitting mode.

  Next, the effect of the present invention at the time of work using hammer drill 10 by a 2nd embodiment is explained. Also in the operation using the hammer drill 10 according to the second embodiment, the power supply current, the acceleration generated in the housing, and the rotational speed of the rotation shaft of the motor are the same as those of the hammer drill 1 according to the first embodiment. It has the characteristics shown in FIG. 8 and FIG.

  In the hammer drill 10 according to the second embodiment, since the operation mode switching unit 9 of the hammer drill 1 according to the first embodiment is not provided, means for determining the state of the operation mode switching unit 9 (magnetic sensor etc.) It was more difficult to detect the kickback that occurs at the time of drilling operation in the rotation and striking mode.

  However, in the present embodiment, the occurrence of kickback is determined based on the rotational speed of the rotary shaft 31 regardless of which tip tool is selected by the operator. Further, as shown in FIGS. 8 (c) and 9 (c), regardless of whether it is a frying operation or a drilling operation, the rotation shaft 31 in the normal operation where no kickback occurs. The fluctuation of the rotational speed is small. That is, in the present embodiment, the rotation of the rotary shaft 31 is stopped according to the rotational speed of the rotary shaft 31 of the motor 3 which changes largely only when kickback occurs during drilling operation where rotational force is applied to the tip tool P3. In order to reduce the change in rotational speed of the rotary shaft 31 of the motor 3 with a small change in the rotational speed of the motor 3 compared to the drilling operation, only the striking force is applied to the tip tool P2. Unpredicted motor drive stoppage due to changes in acceleration is suppressed, and workability is improved.

  Further, as shown in FIG. 9B, when the kickback occurs, the acceleration in the rotational direction of the housing 2 largely fluctuates. In the present embodiment, the condition regarding the rotational speed of the rotary shaft 31 Because the rotation shaft 31 is configured to stop the rotation when the conditions relating to the acceleration generated in the housing 2 are satisfied at the same time, the kickback generated at the time of the drilling operation is detected more accurately, It becomes possible to stop the drive of the motor.

  In the present specification, although the hammer drills 1 and 10 have been described as an example, the present invention is also applicable to a striking work machine driven by a motor other than the hammer drill, for example, a striking work machine such as a vibration drill.

  Further, in the present embodiment, the battery pack Q is used as an example of the drive power supply of the striking work machine, but a general alternating current power supply may be used as the drive power supply.

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 (7)

With the housing,
A motor housed in the housing and having a rotating shaft;
A mounting unit to which the tip tool can be attached and detached;
It is possible to generate an impact force in the first direction on the tip tool by converting the rotary motion of the rotary shaft into a reciprocating motion in the first direction and striking the tip tool, and the rotary motion of the rotary shaft A power transmission unit configured to be capable of causing the tip tool to generate a rotational force in a second direction intersecting the first direction by transmitting the torque to the mounting unit;
An acceleration detection unit that detects an acceleration generated in the housing;
A rotation speed detection unit that detects the number of rotations of the rotation shaft;
Control for stopping the rotation of the rotation shaft when the first condition on the rotation speed detected by the rotation speed detection unit is satisfied and the second condition on the acceleration detected by the acceleration detection unit is satisfied A striking work machine comprising a unit.   The impact working machine according to claim 1, wherein the first condition is that the rate of decrease of the rotational speed of the rotating shaft exceeds a first threshold value for the rotational speed.   The impact working machine according to claim 1 or 2, wherein the second condition is that the acceleration in the second direction generated in the housing exceeds a second threshold.   The power transmission unit has a first power transmission state in which the striking force is transmitted to the tip tool 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 impact working machine according to any one of claims 1 to 3, which is configured to be able to switch between power transmission states.   It has an operation part operated by the worker, and the power transmission state of the power transmission part is mechanically switched between the first power transmission state and the second power transmission state according to the operation of the operation part 5. A striking work implement according to claim 4, further comprising a possible switching mechanism. The mounting portion includes a first portion that can not rotate in the second direction with respect to the housing, and a second portion that can rotate in the second direction with respect to the housing, and the first engaged portion A first tip tool having a second portion and a second tip tool having a second engaged portion are selectively configured to be detachable as the tip tool,
The first portion is provided with a first engaging portion engageable with the first engaged portion,
The second portion is provided with a second engaging portion engageable with the second engaged portion,
When the first tip tool is mounted to the mounting portion, the first tip tool is engaged with the housing by engaging the first engaged portion with the first engaging portion. The first power transmission state can not be rotated in the second direction,
When the second tip tool is mounted on the mounting portion, the second tip tool engages the housing with the second engagement portion engaged with the second engagement portion. The impact working machine according to claim 4, characterized in that the second power transmission state is configured to be rotatable in a second direction. The acceleration detection unit is supported by the housing such that the movement allowance in the first direction with respect to the housing of the acceleration detection unit is larger than the movement allowance in the second direction with respect to the housing of the acceleration detection unit. The impact working machine according to any one of claims 1 to 6, characterized in that.

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