JP6915515B2 - Strike work machine - Google Patents

Description

The present invention relates to a striking work machine.

Conventionally, a striking operation such as forming a hole in a work material (for example, concrete, steel, wood, etc.) by rotating a tip tool by driving a motor, or crushing by applying a striking force to the tip tool. The machine is widely known. As an example of such a striking work machine, as an operation mode, a striking mode for applying only a striking force to the tip tool to crush the work piece, and a striking mode for applying the above striking force to the tip tool and rotating the tip tool. A hammer drill that can be mechanically switched to a rotation / striking mode for drilling a hole in a work material by transmitting a force and rotating a tip tool is known.

In such a hammer drill, the tip tool may get caught in a hard part of the work material and lock the tip tool during drilling work in the rotation / striking mode, and the striking machine body is greatly swung by the drive of the tip tool. There was a possibility that backing would occur and workability would deteriorate.

In order to deal with the above kickback, conventionally, the acceleration and / or the load current value generated in the striking machine main body is detected, and the kickback is performed when either the acceleration and / or the load current value exceeds the threshold value. It is controlled that the rotation of the motor is stopped by judging that the occurrence of the problem has occurred. For example, the hammer drill disclosed in Patent Document 1 has an acceleration sensor that detects the acceleration of the hammer drill body, and stops driving the motor when the acceleration detected by the acceleration sensor exceeds a predetermined acceleration threshold. It is configured to let you.

International Publication No. 2017/145643

However, in the concrete chipping (crushing) work in the striking mode, the operator himself swings the striking machine body, so the acceleration sensor detects the acceleration caused by the swinging of the striking machine body by the operator himself. There was a possibility that the drive of the motor would stop even though kickback did not occur. Further, in the concrete chipping work in the striking mode, since the operation of pressing the tip tool against the work material and the operation of separating the tip tool are repeatedly performed, the load current fluctuates sharply, and the load current during the chipping work is large. It was difficult to distinguish between fluctuations and fluctuations in load current due to kickback during drilling work in the rotation / striking mode.

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

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

According to the striking machine having the above configuration, the tip is stopped in order to stop the rotation of the rotating shaft according to the rotating speed of the rotating shaft of the motor, which changes greatly when kickback occurs during drilling work in which a rotational force is applied to the tip tool. Due to changes in acceleration due to the swinging motion of the striking machine body of the operator during chipping work where the change in the rotation speed of the rotating shaft of the motor is small compared to the drilling work in which only the striking force is applied to the tool. Unexpected motor stoppage is suppressed and workability is improved. In addition, since it is configured to stop the rotation of the rotating shaft when the condition related to the rotational speed of the rotating shaft is satisfied and at the same time the condition related to the acceleration generated in the housing is satisfied, the rotation of the rotating shaft is more accurately performed during drilling work. It is possible to detect the kickback that occurs and stop the drive of the motor.

In the above configuration, the first condition is preferably a condition that the reduction rate of the rotation speed of the rotation shaft exceeds the first threshold value for the rotation speed.

According to such a condition, it is possible to accurately detect the kickback generated during the drilling operation and appropriately stop the motor.

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

According to such a condition, it is possible to accurately detect the kickback generated during the drilling operation and appropriately stop the motor.

Further, the power transmission unit has a first power transmission state in which the striking force is transmitted to the tip tool but no rotational force, 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 can be switched between and.

According to such a configuration, acceleration is generated in the housing according to the power transmission state, but the motor significantly changes when kickback occurs during drilling work in the second power transmission state in which the rotational force is transmitted to the tip tool. Since the rotation of the rotating shaft is stopped according to the rotating speed of the rotating shaft, only the striking force is transmitted to the tip tool, and it depends on the first power transmission state in which the change in the rotating speed of the rotating shaft of the motor is small compared to the drilling work. During the chipping work, the unexpected drive stop of the motor due to the change in acceleration caused by the swinging motion of the striking work machine main body of the operator is suppressed, and the workability is improved. In addition, since it is configured to stop the rotation of the rotating shaft when the condition related to the rotational speed of the rotating shaft is satisfied and at the same time the condition related to the acceleration generated in the housing is satisfied, the rotation of the rotating shaft is more accurately performed during drilling work. It is possible to detect the kickback that occurs and stop the drive of the motor.

Further, it has an operation unit operated by an operator, and the power transmission state of the power transmission unit is mechanically changed between the first power transmission state and the second power transmission state in accordance with the operation of the operation unit. It is preferable to further have a switching mechanism unit that can be switched.

According to the above configuration, in order to stop the driving of the motor according to the rotation speed of the rotation shaft of the motor and the acceleration generated in the housing, 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 unit. That is, it is possible to detect the kickback that occurs during the drilling operation in the second power transmission state without increasing the number of parts.

Further, the mounting portion has a first portion that cannot 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 has a first cover. A first tip tool having an engaging portion and a second tip tool having a second engaged portion are selectively detachably attached and detached as the tip tool, and the first portion is provided with the first engaged portion. A first engaging portion that can be engaged with the portion is provided, a second engaging portion that can be engaged with the second engaged portion is provided in the second portion, and the first tip tool is said to be the same. When mounted on the mounting portion, the first tip tool cannot rotate in the second direction with respect to the housing due to the engagement between the first engaged portion and the first engaging portion. When the second tip tool is mounted on the mounting portion in the first power transmission state, the second tip is engaged by engaging the second engaged portion with the second engaging portion. It is preferable that the tool is in the second power transmission state in which the tool can rotate in the second direction with respect to the housing.

According to the above configuration, the drive of the motor is stopped according to the rotation speed of the rotation shaft of the motor and the acceleration generated in the housing. Therefore, even when the power transmission state is switched by selectively attaching and detaching the tip tool. , It is possible to preferably detect the kickback that occurs during the drilling operation in the second power transmission state.

The acceleration detection unit is supported by the housing so 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 preferable.

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.
The present invention further comprises a housing, a motor housed in the housing and having a rotating shaft, a mounting portion to which a tip tool can be attached and detached, and the tip tool by converting the rotational motion of the rotating shaft into a reciprocating motion in the first direction. By striking, the tip tool can generate a striking force in the first direction, and by transmitting the rotational motion of the rotation shaft to the mounting portion, the tip tool intersects the first direction. In addition to being able to generate a rotational force in the second direction, the first power transmission state in which the striking force is transmitted to the tip tool while the rotational force is not transmitted, and at least the rotational force is transmitted to the tip tool. A power transmission unit configured to switch the power transmission state between the second power transmission state to which is transmitted, an acceleration detection unit that detects the acceleration generated in the housing, and the rotation speed of the rotation shaft are detected. When the first condition regarding the rotation speed detection unit and the rotation speed detected by the rotation speed detection unit is satisfied, and the second condition regarding the acceleration detected by the acceleration detection unit is satisfied, the rotation is performed. A control unit for stopping the rotation of the shaft is provided, and the first condition and the second condition for stopping the rotation of the rotating shaft include the first power transmission state and the second power transmission state. It provides a striking work machine characterized by being common among them.
In the above configuration, it is preferable that the control unit cannot determine whether the power transmission unit is in the first power transmission state or the second power transmission state.
The present invention further comprises a housing, a motor housed in the housing and having a rotating shaft, a mounting portion to which a tip tool can be attached and detached, and the tip tool by converting the rotational motion of the rotating shaft into a reciprocating motion in the first direction. By striking, the tip tool can generate a striking force in the first direction, and by transmitting the rotational motion of the rotation shaft to the mounting portion, the tip tool intersects the first direction. A power transmission unit configured to generate a rotational force in the second direction, an acceleration detection unit that detects the acceleration generated in the housing, a rotation speed detection unit that detects the rotation speed of the rotation shaft, and the like. Control to stop the rotation of the rotation shaft when the first condition regarding the rotation speed detected by the rotation speed detection unit is satisfied and the second condition regarding the acceleration detected by the acceleration detection unit is satisfied. The acceleration detection unit is provided with a unit, so 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. It provides a striking machine characterized by being supported by a housing.

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

It is an overall cross-sectional view which shows the internal structure of the hammer drill which concerns on 1st Embodiment of this invention. It is a top view of the hammer drill which concerns on 1st Embodiment of this invention. FIG. 1 is a partially enlarged cross-sectional view of FIG. 1, showing an embodiment in which the accelerometer support portion of the hammer drill according to the first embodiment of the present invention supports the accelerometer. FIG. 3 is a sectional view taken along line IV-IV of FIG. 3, showing an embodiment in which the accelerometer support portion of the hammer drill according to the first embodiment of the present invention supports the accelerometer. FIG. 1 is a view in the direction of arrow V of FIG. 1, showing an embodiment 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 a circuit diagram which shows the electric structure of the hammer drill which concerns on 1st Embodiment of this invention. It is a flowchart which shows the operation of the hammer drill which concerns on 1st Embodiment of this invention. (A) Power supply current, (b) Acceleration in the rotation direction generated in the housing, and (c) Time change of the rotation speed of the rotor during the chipping (crushing) operation of the hammer drill according to the first embodiment of the present invention. It is a graph which shows. A graph showing (a) power supply current, (b) acceleration in the rotation direction generated in the housing, and (c) time change of the rotation speed of the rotor during the drilling operation of the hammer drill according to the first embodiment of the present invention. Is. It is an overall cross-sectional view which shows the internal structure of the hammer drill which concerns on 2nd Embodiment of this invention. FIG. 10 is a cross-sectional view taken along the line XI-XI of FIG. 10, showing a first tool holding portion of a hammer drill according to a second embodiment of the present invention. FIG. 10 is a cross-sectional view taken along the line XII-XII of FIG. 10, showing a second tool holding portion of the hammer drill according to the second embodiment of the present invention. It is a figure which shows the tip tool P2 which can be attached and detached to the mounting part of the hammer drill which concerns on the 2nd Embodiment of this invention, (a) is a rear view, (b) is a side view. It is a figure which shows the tip tool P3 which can be attached and detached to the mounting part of the hammer drill which concerns on the 2nd Embodiment of this invention, (a) is a rear view, (b) is a side view.

The hammer drill 1 which is an example of the striking work machine according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 9. The hammer drill 1 is an electric striking work machine for forming a perforated hole in a work material (for example, concrete, steel, wood, etc.) or crushing it by applying a striking force. The hammer drill 1 has two operation modes: a "rotation / striking mode" in which the tip tool P1 rotates to pierce the work material and hits the work material, and a "striking mode" in which the tip tool P1 hits the work material. ".

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. In addition, when the hammer drill is viewed from behind, "right" is defined as the right direction, and "left" is defined as the left direction. When the dimensions, numerical values, etc. are referred to in the present specification, not only the dimensions and numerical values that completely match the dimensions, numerical values, etc., but also the dimensions, numerical values, etc. that substantially match (for example, when it is within the range of manufacturing error). ) Shall be included. Similarly for "identical", "orthogonal", "parallel", "matching", "facial", "constant", etc. It shall include "substantially flush", "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 unit 4, a control unit 5, a power transmission unit 6, an output unit 7, and an acceleration sensor 8. It mainly has an operation mode switching unit 9.

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. Housing 2 is an example of a "housing" in the present invention.

The motor housing 21 has a 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 has a rotating shaft 31, a rotor 32, a stator 33, and a fan 34.

The rotating shaft 31 extends in the vertical direction and is rotatably supported by the housing 2. A pinion 31A that rotates integrally with the rotating shaft 31 is fixed to the upper end of the rotating 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 peripheral surface of the motor housing 21. Further, the stator winding 33A has star-connected three-phase coils U, V, and 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 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 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. 6).

The gear housing 22 is made of metal, is connected to the upper part of the motor housing 21, and extends in the front-rear direction. The gear housing 22 houses a power transmission unit 6, an output unit 7, and a part of an operation mode switching unit 9 inside the gear housing 22. Further, a side handle 2A gripped 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 has a power conversion mechanism 61 and a rotational force transmission mechanism 62 having a bevel gear formed at the upper end portion, and converts the rotational motion of the rotary 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 a striking force in the front-rear direction on the tip tool P1, and by transmitting the rotational motion of the rotating shaft 31 to the output unit 7, the axis A on the tip tool P1. It is configured to be able to generate a rotational force in the rotational direction centered on. Further, the power transmission unit 6 is configured so that the drive state of the tip tool P1 can be changed by switching the power transmission state. Specifically, the power transmission unit 6 has a "striking mode" in which the striking force is transmitted to the tip tool P1 but no rotational force, and a "rotation / striking mode" in which the striking force and the rotational force are transmitted to the tip tool. The power transmission state can be switched between. It should be noted that the power transmission state is set between the "striking mode" in which the striking force is transmitted to the tip tool but the rotational force is not transmitted, and the "rotation mode" in which the rotational force is transmitted to the tip tool but the striking force is not transmitted. It may be configured to be switchable. In the following description, the "rotational direction around the axis A" is simply referred to as the "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 / striking mode is an example of the "second power transmission state" in the present invention.

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

The striking element 71 is configured to be reciprocating by a power conversion mechanism 61. Specifically, the front end of the striking tool 71 is configured to be able to come into contact with the rear end of the tip tool P1 mounted on the mounting portion 73, and as the striking tool 71 reciprocates in the front-rear direction, the tip tool P1 The striking force is transmitted to.

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 transmission mechanism 62. Further, the mounting portion 73 is rotated by the rotation of the cylinder 72, 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 FIGS. 1 and 2, the operation mode switching unit 9 is located above the rear portion of the gear housing 22, and is configured so that the power transmission state of the power transmission unit 6 can be mechanically switched. .. 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 rotational movement to the output unit 7 via the rotational force transmission mechanism 62. By switching between the shut-off state, the striking mode and the rotation / striking mode can be switched. Further, in the present embodiment, the transmission of the striking force to the tip tool P1 via the power conversion mechanism 61 during work cannot be interrupted. 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 part operated by the operator when switching the operation mode, and has a substantially circular shape in the top view as shown in FIG. The operation unit 91 is configured to be rotatable. In this embodiment, the magnetic sensor or the like for determining the state of the operation unit 91 is not provided, and the control unit 5 can determine the mode selected from the state of the operation mode switching unit 9. It is configured to be impossible. 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. A bevel gear that can be meshed with the bevel gear of the rotational force transmission mechanism 62 is formed at the front end portion of the sleeve 92. The inner diameter of the sleeve 92 is 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. Further, the sleeve 92 is configured to be rotatable integrally with the cylinder 72.

The back cover 23 extends in the vertical direction and is arranged 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 insertion portion 23A projects rearward below the back cover 23. A through hole penetrating in the left-right direction is formed in the insertion portion 23A.

The connecting portion 23B 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 on the hammer drill 1. The control unit 5 has a flat plate-shaped 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 has a substantially U-shaped 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 grip portion 24A is a portion 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 part of the front portion of the grip portion 24A. A switch mechanism (not shown) connected to the control unit 5 is provided inside the grip unit 24A. When the trigger 24D is pulled, that is, started (for example, when the trigger 24D is pushed into the handle housing 24 by the operator's finger), the switch mechanism sends a tool start signal for starting the motor 3 to the control unit 5. When the pull operation on the trigger 24D is released, that is, the stop operation is performed (for example, when the operator releases the pull operation by releasing the finger from the trigger 24D), the output of the tool start signal is stopped. There is.

The first connecting 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 connecting portion 24B. The shaft 24E is inserted into the through hole of the insertion portion 23A. The handle housing 24 is configured to be rotatable around the shaft 24E as a fulcrum. Further, a battery mounting portion 24F to which the battery pack Q can be mounted is provided below the first connecting portion 24B. The hammer drill 1 is configured to be driveable by power supply from the battery pack Q mounted on the battery mounting portion 24F.

The second connecting portion 24C extends forward from the upper end portion of the grip portion 24A. The second connecting portion 24C is provided with a vibration reducing mechanism 2B having an elastic body (not shown), and the second connecting portion 24C is connected to the connecting portion 23B of the back cover 23 via the vibration reducing mechanism 2B. Even when vibration in the axis A direction occurs in the output unit 7, the handle housing 24 rotates around the shaft 24E, and the elastic body (not shown) of the vibration reduction mechanism 2B expands and contracts, so that the vibration in the axis A direction vibrates. Is absorbed, and the vibration in the axis A direction is reduced from being transmitted to the operator who grips the grip 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. 4 and 5, the acceleration sensor support portion 25 is symmetrically configured. 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 accommodating wall portion 251 has a substantially U-shape in rear view, and as shown in FIG. 3, protrudes rearward from the rear wall portion of the motor housing 21.

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

The acceleration sensor 8 is arranged in the accommodating wall portion 251 of the acceleration sensor support portion 25, and is configured to be able to detect each acceleration 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 conducting wire 8A, and controls an acceleration signal according to the detected direction and magnitude of the acceleration of the housing 2. It is configured to be output to unit 5. The acceleration sensor 8 is configured to be able to independently detect at least the acceleration in the front-rear direction and the rotation direction (left-right direction) of the housing 2. Further, in the present embodiment, the acceleration sensor 8 is located at a position away from the axis A of the tip tool P1. More specifically, the acceleration sensor 8 is provided so that its position in the vertical direction overlaps with the battery pack Q. This makes it 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 "acceleration detection unit" in the present invention.

The case 82 is made of resin and is symmetrically configured as shown in FIG. 3 and symmetrically as shown in FIG. The substrate 81 is arranged 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. 3, the case 82 is fixed to the housing 2 by the pressing portion 253 with its front and rear side surfaces 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 accommodating wall portion 251.

Here, since the spring constant of the elastic body 252 is smaller than the left and right side walls of the accommodating wall portion 251, the accelerometer 8 has a housing of the accelerometer 8 having a movement allowance in the front-rear direction with respect to the housing 2 of the accelerometer 8. It is supported by the acceleration sensor support portion 25 so as to be larger than the movement allowance in the rotation direction about the axis A with respect to 2. This makes it possible to appropriately detect the acceleration of the housing 2 in the rotation 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 configuration 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 houses a plurality of batteries that serve as power sources for the motor 3, the control unit 5, and the like.

The battery pack Q has a positive terminal and a negative 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 main body side, respectively, and the voltage of the battery pack Q is set to the predetermined value. It is configured to be applied between the terminals of.

The switching circuit 41 is an inverter circuit for supplying 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 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 be able 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 a signal (acceleration signal) indicating the value (magnitude) of the detected acceleration in the front-rear direction and the rotation direction to the control unit 5.

The board 51 of the control unit 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. , Communication circuit 51I, battery temperature detection circuit 51J, and over-discharge detection circuit 51K are mounted.

The controller 51A stores a processing program used for controlling the motor 3 and a calculation unit (not shown) having a central processing unit (CPU) that performs calculations based on various data, and stores the processing program, various data, various thresholds, and the like. It is provided with a ROM (not shown) and a storage unit having a RAM (not shown) for temporarily storing data. The controller 51A controls the motor 3 according to the processing program.

Further, the controller 51A performs rotation drive control as basic control for the motor 3. The rotation drive control is a control for rotationally driving 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 conductive switching member among the switching members based on the rotation 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 rotation 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 rotation speed [rpm] of the rotation shaft 31 (motor 3) per unit time (in the following description, simply referred to as “rotation speed”) is a target corresponding to each operation mode. Rotational drive control is performed while feedback control is performed so that the number of rotations is reached. More specifically, the controller 51A calculates the rotation speed of the rotation 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 makes the comparison. Based on the result, the constant rotation speed control is performed by repeatedly executing the process of changing the duty ratio of the PWM signal so that the rotation speed of the rotation shaft 31 becomes the target rotation speed at high speed.

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

The control signal output circuit 51B is connected to each gate 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 rotation position of the rotor 32 based on the signal output from the magnetic sensor unit 42 and outputs a signal (rotation position signal) indicating the detected rotation position to the controller 51A. .. In the present embodiment, the rotation position of the rotation shaft 31 is detected by detecting the magnetic field of the magnet 34A attached to the fan 34 that rotates integrally with the rotation shaft 31, but the rotation shaft 31 is configured. It may be configured to directly detect the rotation position of.

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 a 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 through the motor 3 by using the voltage drop value of the shunt resistance 50 provided between the switching circuit 41 and the battery pack Q, and detects the detected motor current. This is a circuit that outputs a signal indicating a value (current value signal) to the controller 51A.

The step-down circuit 51G is a circuit that steps down (for example, 5V) the voltage (for example, 14.4V) 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 / outputs battery identification information and tool identification information between the controller 51A and the 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 over-discharge detection circuit 51K is a circuit capable of detecting the over-discharge of the battery pack Q, and when the over-discharge is detected, outputs a signal indicating the over-discharge to the controller 51A.

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 faces substantially rearward, the rotation / striking mode is selected. On the other hand, when the triangular mark 91A formed on the operation unit 91 faces substantially forward, the striking mode is selected.

Specifically, as shown in FIG. 2, when the triangular mark 91A formed on the operation unit 91 faces substantially rearward, the sleeve 92 shown in FIG. 1 faces the cylinder 72. The bevel gear of the sleeve 92 meshes with the bevel gear of the rotational force transmission mechanism 62, thereby rotating the output unit 7 (cylinder 72) via the rotational force transmission mechanism 62 and applying the rotational force to the tip tool P1. It will be in a state where it can be transmitted. In the present embodiment, at the same time, the output unit 7 (striking element 71) can be reciprocated via the power conversion mechanism 61 to transmit the striking force to the tip tool P. That is, the rotation / striking mode is such that the striking force and the rotational force can be transmitted to the tip tool P.

Further, when the triangular mark 91A formed on the operation unit 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 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 cut off. At this time, the output unit 7 is reciprocated via the power conversion mechanism 61 to enter a striking mode in which only the striking force can be transmitted to the tip tool P1.

Next, according to the flowchart shown in FIG. 7, a process of detecting a kickback that occurs during a drilling operation using the rotation / striking mode by the controller 51A of the control unit 5 will be described.

When the operator mounts the battery pack Q on the battery mounting portion 24F of the handle housing 24, electric power is supplied to the controller 51A (control unit 5), and the process shown in the flowchart of FIG. 7 is started with this as an opportunity. ..

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

When it is determined in step S101 that the pull operation has not been performed on the trigger 24D (step S101: No), the controller 51A repeats the determination process of step S101. At the start of the work, since the motor 3 is not driven, the process of step S110 is not executed. On the other hand, when it is determined in step S101 that the pulling operation is being performed on the trigger 24D (step S101: Yes), the controller 51A starts the motor drive control (constant speed control) 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 a switching operation for rotating the rotor 32 in a predetermined rotation direction based on the drive signal output from the control unit 5. As a result, the motor 3 is driven, the driving force of the motor 3 is transmitted to the output unit 7 via the power transmission unit 6, and the tip tool P starts rotating and striking according to the operation mode selected by the operator.

Next, the controller 51A detects the rotation speed of the rotation shaft 31 and the acceleration in the rotation direction of the housing 2 (step S103). Specifically, the controller 51A calculates the rotation speed of the rotation shaft 31 based on the rotation position signal output from the rotor position detection circuit 51C. Further, the acceleration sensor 8 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 "rotation speed detection unit" in the present invention.

Next, the controller 51A determines whether or not the difference between the rotation speed of the rotation shaft 31 detected in step S103 and the rotation speed of the rotation shaft 31 before a predetermined time exceeds the first threshold value (step S104). .. In other words, the controller 51A determines whether or not the reduction rate of the rotation speed of the rotation shaft 31 exceeds the first threshold value for the rotation speed. In the present embodiment, the predetermined time is "20 ms" and the first threshold value is "1500 [rpm]". The predetermined time and the first threshold value may be within an appropriate range for determining 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 rotation speed of the rotor 32 and the rotation speed of the rotor 32 before a predetermined time exceeds the first threshold value" is an example of the "first condition" in the present invention.

When it is determined that the difference between the rotation speed of the rotation shaft 31 detected in step S104 and the rotation speed of the rotation shaft 31 20 ms before exceeds 1500 [rpm] (step S104: Yes), the controller 51A performs the controller 51A in step S105. , Execute rotation speed flag processing. Here, the rotation speed flag is composed of 1 bit (binary value) indicating whether or not the difference between the rotation speed of the rotation shaft 31 and the rotation speed of the rotation shaft 31 20 ms before exceeds 1500 [rpm]. It is a flag. In the present embodiment, when the controller 51A determines that the difference between the rotation speed of the rotation shaft 31 and the rotation speed of the rotation shaft 31 20 ms before exceeds 1500 [rpm] (step S104: Yes), in step S105. "1" is set. In this embodiment, "0" is set as the initial value of the rotation speed flag. Further, in the present embodiment, once "1" is set as the rotation speed flag in step S105, the state in which the "1" is set is maintained for 100 ms, and after 100 ms, "1" is set. It is configured to be initialized to "0". At the start of the work, since the rotation speed of the rotation shaft 31 before the predetermined time does not exist, the step S105 is configured to be executed after the predetermined time has elapsed.

In any case after the rotation speed flag processing is performed in step S105, or when it is determined in step S104 that the difference between the rotation speed of the rotor 32 and the rotation speed of the rotor 32 20 ms before does not exceed the first threshold value. In step S106, the controller 51A determines whether or not the magnitude of the acceleration in the rotational direction generated in the housing 2 exceeds the second threshold value. In the present embodiment, the second threshold value is "4 [G]". The second threshold value may be in an appropriate 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. Further, "whether or not the magnitude of the acceleration in the rotational direction generated in the housing 2 exceeds the second threshold value" 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 executes the acceleration flag processing in step S107. .. Here, the acceleration flag is a flag composed of 1 bit (binary value) indicating whether or not the magnitude of the acceleration in the rotation direction generated in the housing 2 exceeds 4 [G]. In the present embodiment, when the controller 51A determines that the acceleration of the housing 2 in the rotational direction exceeds 4 [G] (step S106: Yes), “1” is set in step S107. In this embodiment, "0" is set as the initial value of the acceleration flag. Further, in the present embodiment, once "1" is set as the acceleration flag in step S107, the state in which the "1" is set is maintained for 100 ms, and "0" is maintained after 100 ms has elapsed. It is configured to be initialized to.

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

When it is determined that "1" is set in both the rotation speed flag and the acceleration flag (step S108: Yes), the controller 51A determines that kickback has occurred 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 speed flag and the acceleration flag (step S108: No), the state of the trigger 24D is subsequently monitored (step S101), and the kickback as described above is performed. The process of determining the above (step S103 to step S108) is repeated. 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 regarding the rotation speed of the rotation shaft 31 detected by the rotor position detection circuit 51C and the controller 51A and the condition regarding the acceleration detected by the acceleration sensor 8. Stops the rotation of the rotating shaft 31. That is, in order to stop the rotation of the rotating shaft 31 according to the rotational speed of the rotating shaft 31 of the motor 3, which changes significantly when kickback occurs during the drilling work in which the rotational force is applied to the tip tool P1, the tip tool P1 is hit. An unexpected motor due to a change in acceleration due to the swinging motion of the hammer drill body of the operator during chipping work in which only force is applied and the change in the rotation speed of the rotation shaft 31 of the motor 3 is small compared to the time of drilling work. The drive stop of No. 3 is suppressed, and workability is improved. Further, since it is configured to stop the rotation of the rotating shaft 31 when the condition related to the rotation speed of the rotating shaft 31 is satisfied and at the same time the condition related to the acceleration generated in the housing 2 is satisfied, the rotation of the rotating shaft 31 is stopped more accurately. It is possible to detect the kickback generated during the drilling operation and stop the driving of the motor 3.

Next, the effect 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, when drilling in the rotation / striking mode (rotation mode) using a hammer drill, the tip tool may get caught in a hard part of the work piece and the tip tool may lock, and the hammer drill body becomes large due to the drive of the tip tool. There was a possibility that kickback would occur and workability would deteriorate. Therefore, a striking machine that accurately detects kickback has been desired.

Here, as shown in FIG. 8A, in the concrete chipping (crushing) operation in the striking mode, the operation of pressing the tip tool against the work material and the operation of separating the tip tool are repeatedly performed. Therefore, the fluctuation of the current value is large, and the fluctuation of the current value during the chipping work and the fluctuation of the current value due to the kickback during the drilling work 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 the acceleration generated in the housing is used as a reference for determining the occurrence of kickback, the acceleration sensor is used because the operator himself swings the hammer drill body in the concrete chipping work in the striking mode. The acceleration caused by the swinging of the hammer drill body by the operator himself was detected, and the drive of the motor was stopped even though kickback did not occur, which may deteriorate the workability. Further, as shown in FIGS. 8 (b) and 9 (b), the value of the acceleration in the rotation direction generated in the housing fluctuates even during normal work in which kickback does not occur. It was difficult to detect the occurrence of kickback based only on acceleration.

Further, it is conceivable to provide a means (magnetic sensor or the like) for determining the state of the operation mode switching unit, but there is a possibility that the number of parts may increase.

However, in the present embodiment, the occurrence of kickback is determined based on the rotation speed of the rotation shaft 31. As shown in FIGS. 8 (c) and 9 (c), the number of rotations of the rotating shaft 31 during normal work in which kickback does not occur regardless of whether the work is chipping work or drilling work. Fluctuations are small. That is, in the present embodiment, the rotation of the rotating shaft 31 is stopped according to the rotational speed of the rotating shaft 31 of the motor 3, which changes significantly only when kickback occurs during the drilling work in which the rotational force is applied to the tip tool P1. This is caused by the swinging operation of the hammer drill body of the operator during the chipping work in which only the striking force is applied to the tip tool P1 and the change in the rotation speed of the rotating shaft 31 of the motor 3 is small as compared with the drilling work. Unexpected drive stoppage of the motor due to changes in acceleration is suppressed, and workability is improved.

Further, as shown in FIG. 9B, when kickback occurs, the acceleration in the rotation direction of the housing 2 fluctuates greatly. However, in the present embodiment, the condition relating to the rotation speed of the rotation shaft 31 At the same time, the rotation of the rotating shaft 31 is stopped when the condition related to the acceleration generated in the housing 2 is satisfied. Therefore, the kickback generated during the drilling work is detected more accurately. It is possible to stop the drive of the motor.

Further, since kickback is detected by using an acceleration sensor, a rotation position detection circuit, or the like which is generally provided in a hammer drill, it is possible to suppress an increase in the number of parts.

Next, the hammer drill 10 which is an example of the striking work machine according to the 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 description of the same configuration as that of the hammer drill 1 will be omitted as appropriate, and different configurations will be mainly described. do. Further, the hammer drill 10 has the same electrical configuration as the hammer drill 1, and performs a process of determining kickback according to the flowchart shown in FIG. 7. In this 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, the output unit 17 is provided in place of the output unit 7. Further, a gear housing 122 is provided in place of the gear housing 22.

The output unit 17 has a striking element 171, a cylinder 172, and a mounting unit 173.

The striker 171 is configured to be reciprocating by the power conversion mechanism 61 of the power transmission unit 6. Specifically, the front end of the striking element 171 is configured to be able to come into contact with the rear end of the tip tool mounted on the mounting portion 173, and as the striking element 171 reciprocates in the front-rear direction, it strikes the tip tool. 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 holding portion 173A is fixed to the gear housing 22 by the fixing member 122A. As a result, the first tool holding portion 173A is configured to be relatively non-rotatable with respect to the housing 2. Further, as shown in FIGS. 10 and 11, the first tool holding portion 173A has a first engaging portion 173C forming a front portion thereof. The first tool holding portion 173A is an example of the "first portion" in the present invention. The first engaging portion 173C is an example of the "first engaging 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 holding portion 173B is configured to be rotatable relative to the housing 2. As shown in FIGS. 10 and 12, the second tool holding portion 173B has a second engaging portion 173D forming a front portion thereof. The second tool holding portion 173B is an example of the "second portion" in the present invention. The second engaging portion 173D is an example of the "second engaging portion" in the present invention.

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

Next, the configurations of the tip tool P2 and the tip tool P3 that can be selectively attached to and detached from the mounting portion 173 will be described with reference to FIGS. 13 and 14. The direction will be described with reference to the state in which the tip tool P2 and the tip tool P3 are mounted on 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 regulation portion P24.

The bit portion P21 has a substantially cylindrical shape extending in the front-rear direction. The front end portion of the bit portion P21 is formed so as to be sharpened toward the front.

As shown in FIG. 13, the engaged portion P22 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 prism 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. As a result, the first engaging portion 173C and the engaged portion P22 can be engaged with each other. Further, the tip tool P2 is configured to be unable to rotate relative to the housing 2 by engaging the first engaging portion 173C which cannot rotate relative 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 extending portion P23 is shorter than the distance from the axis A to each surface forming the insertion hole 173b of the second engaging portion 173D.

The restricting portion P24 is formed in a substantially disk shape slightly extending in the front-rear direction, and is provided at the front end of the engaged portion P22. As shown in FIG. 13A, the radius of the regulating 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 regulation portion P34.

The bit portion P31 has a substantially cylindrical shape extending in the front-rear direction. The front end portion of the bit portion P31 is formed so as to be sharpened toward the front. Further, a spiral rib is provided on the peripheral surface of the bit portion P31 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 to be slightly smaller than the insertion hole 173b formed in the substantially regular hexagonal prism shape of the second engaging 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. As a result, the second engaging portion 173D and the engaged portion P32 can be engaged with each other. Further, the tip tool P3 is configured to be relatively rotatable with respect to the housing 2 by engaging the second engaging portion 173D which is relatively rotatable with respect 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 extending portion P33 is formed in a substantially cylindrical shape extending in the front-rear direction. As shown in FIG. 13A, the radius of the extending portion P33 is shorter than the distance from the axis A to each surface of the engaged portion P32. Further, the radius of the extending portion P33 is shorter than the distance from the axis A to each surface forming the insertion hole 173a of the first engaging portion 173C.

The regulating portion P34 is formed in a substantially disk shape slightly extending in the front-rear direction, and is provided at the front end of the extending portion P33. As shown in FIG. 14A, the radius of the regulating portion P34 is configured to be larger than the radius of the extending portion P33. Further, although not shown in the figure, the radius of the regulating portion P34 is configured to be longer than the distance from the axis A to each surface forming the insertion hole 173a of the first engaging portion 173C.

Next, the operation of switching 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 tip tool P2 and the tip tool P3 are selectively attached and detached to operate. Switch modes.

More specifically, when the operator performs the chipping work, the tip tool P2 is brought closer to the insertion hole 173a of the first engaging portion 173C of the first tool holding portion from the extension portion P23 side and inserted. .. At this time, the tip tool P2 is positioned with respect to the housing 2 by the contact between the rear surface of the regulation portion P24 of the tip tool P2 and the front surface of the first engaging portion 173C. In this state, the engaged portion P22 of the tip tool P2 is located at substantially the same position as the insertion hole 173a of the first engaging portion 173C in the front-rear direction, and the extending portion P23 is the insertion hole 173b of the second engaging portion 173D. It is located at approximately the same position in the front-back direction.

In this state, the first engaging portion 173C, which cannot rotate relative to the housing 2, and the engaged portion P22 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 to be shorter than the distance to, the rotational force is not transmitted to the tip tool P2. On the other hand, as the striking element 171 reciprocates in the front-rear direction, the striking force is transmitted to the tip tool P2. At this time, the movement of the tip tool P2 in the striking direction 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 engaging the engaged portion P22 and the first engaging portion 173C. It becomes an impossible hit mode.

When the operator performs the drilling work, the tip tool P3 is brought closer 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 the contact between the rear surface of the regulation portion P34 of the tip tool P3 and the front surface of the first engaging portion 173C. In this state, the engaged portion P32 of the tip tool P3 is located at substantially the same position as the insertion hole 173b of the second engaging portion 173D in the front-rear direction, and the extending portion P33 is the insertion hole 173a of the first engaging portion 173C. It is located at approximately the same position in the front-back direction.

In this state, the second engaging portion 173D that can rotate relative to the housing 2 and the engaged portion P32 are engaged, and the radius of the extending portion P33 is from the axis A to the insertion of the first engaging portion 173C. Since the distance to each surface forming the hole 173a is shorter than the distance to each surface, the rotational force is transmitted to the tip tool P3. Further, as the striking element 171 reciprocates in the front-rear direction, the striking force is transmitted to the tip tool P3. At this time, the movement of the tip tool P3 in the striking direction is guided by the inner peripheral surface of the second engaging portion 173D forming the insertion hole 173b. That is, when the tip tool P3 is mounted on the mounting portion 173, the tip tool P3 can rotate with respect to the housing 2 by engaging the engaged portion P32 and the second engaging portion 173D. It becomes the striking mode.

Next, the effect of the present invention at the time of working with the hammer drill 10 according to the second embodiment will be described. In the work using the hammer drill 10 according to the second embodiment, the power supply current, the acceleration generated in the housing, and the rotation 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 FIGS. 8 and 9.

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, a means for determining the state of the operation mode switching unit 9 (magnetic sensor or the like). It was more difficult to detect the kickback that occurs during the drilling work in the rotation / striking mode.

However, in the present embodiment, regardless of which tip tool is selected by the operator, the occurrence of kickback is determined based on the rotation speed of the rotation shaft 31. Further, as shown in FIGS. 8 (c) and 9 (c), the rotating shaft 31 during normal work in which kickback does not occur, regardless of whether it is chipping work or drilling work. The fluctuation of the rotation speed is small. That is, in the present embodiment, the rotation of the rotating shaft 31 is stopped according to the rotating speed of the rotating shaft 31 of the motor 3, which changes significantly only when kickback occurs during the drilling work in which the rotational force is applied to the tip tool P3. This is caused by the swinging operation of the hammer drill body of the operator during the chipping work in which only the striking force is applied to the tip tool P2 and the change in the rotation speed of the rotating shaft 31 of the motor 3 is small as compared with the drilling work. Unexpected drive stoppage of the motor due to changes in acceleration is suppressed, and workability is improved.

Further, as shown in FIG. 9B, when kickback occurs, the acceleration in the rotation direction of the housing 2 fluctuates greatly. However, in the present embodiment, the condition relating to the rotation speed of the rotation shaft 31 At the same time, the rotation of the rotating shaft 31 is stopped when the condition related to the acceleration generated in the housing 2 is satisfied. Therefore, the kickback generated during the drilling work is detected more accurately. It is possible to stop the drive of the motor.

In the present specification, the hammer drills 1 and 10 have been described as an example, but the present invention can also be applied 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 source of the striking work machine, but a general AC power source may be used as the drive power source.

1 ... Hammer drill 2 ... Housing 3 ... Motor 4 ... Inverter circuit board 5 ... Control 6 ... Power transmission 7 ... Output 8 ... Accelerometer 9 ... Operation mode switching

Claims (7)

With the housing
A motor housed in the housing and having a rotating shaft,
With a mounting part where the tip tool can be attached and detached
By converting the rotary motion of the rotary shaft into a reciprocating motion in the first direction and striking the tip tool, it is possible to generate a striking force in the first direction of the tip tool, and the rotary motion of the rotary shaft. while the is configured to be capable causes rotation force in a second direction crossing the first direction to the tip tool Rutotomoni, the striking force to the tool bit is transmitted by transmission to the mounting portion A power transmission unit configured to switch between a first power transmission state in which 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.
An acceleration detection unit that detects the acceleration generated in the housing, and
A rotation speed detection unit that detects the number of rotations of the rotation shaft,
Control to stop the rotation of the rotation shaft when the first condition regarding the rotation speed detected by the rotation speed detection unit is satisfied and the second condition regarding the acceleration detected by the acceleration detection unit is satisfied. With a department ,
The first condition and the second condition for stopping the rotation of the rotating shaft are common between the first power transmission state and the second power transmission state. Machine. The striking work machine according to claim 1, wherein the first condition is a condition that the reduction rate of the rotation speed of the rotation shaft exceeds the first threshold value for the rotation speed. The striking work machine according to claim 1 or 2, wherein the second condition is a condition that the acceleration generated in the housing in the second direction exceeds the second threshold value. The method according to any one of claims 1 to 3, wherein the control unit cannot determine whether the power transmission unit is in the first power transmission state or the second power transmission state. Strike work machine. It has an operation unit operated by an operator, and mechanically switches the power transmission state of the power transmission unit between the first power transmission state and the second power transmission state according to the operation of the operation unit. The striking work machine according to any one of claims 1 to 4, further comprising a possible switching mechanism unit. The mounting portion has a first portion that cannot 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 has a first engaged portion. A first tip tool having a portion and a second tip tool having a second engaged portion are selectively detachably configured as the tip tool.
The first portion is provided with a first engaging portion that can be engaged with the first engaged portion.
The second portion is provided with a second engaging portion that can be engaged with the second engaged portion.
When the first tip tool is mounted on the mounting portion, the first tip tool engages with the first engaging portion so that the first tip tool is attached to the housing. In the first power transmission state, which cannot rotate in the second direction,
When the second tip tool is mounted on the mounting portion, the second tip tool engages with the second engaging portion so that the second tip tool is attached to the housing. The striking work machine according to any one of claims 1 to 5, wherein the second power transmission state is rotatable in a second direction. With the housing
A motor housed in the housing and having a rotating shaft,
With a mounting part where the tip tool can be attached and detached
By converting the rotary motion of the rotary shaft into a reciprocating motion in the first direction and striking the tip tool, it is possible to generate a striking force in the first direction of the tip tool, and the rotary motion of the rotary shaft. A power transmission unit configured to be able to generate a rotational force in the tip tool in a second direction intersecting the first direction by transmitting the above to the mounting unit.
An acceleration detection unit that detects the acceleration generated in the housing, and
A rotation speed detection unit that detects the number of rotations of the rotation shaft,
Control to stop the rotation of the rotation shaft when the first condition regarding the rotation speed detected by the rotation speed detection unit is satisfied and the second condition regarding the acceleration detected by the acceleration detection unit is satisfied. With a department,
The acceleration detection unit is supported by the housing so 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. A striking work machine characterized by that.

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