JP2020055058A - Striking work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a striking work machine capable of stabilizing a state in which a striking portion strikes a tool support portion. SOLUTION: The striking work machine 10 is provided with an anvil 27 having a protrusion 32, a hammer 43 having a protrusion 51, and an electric motor 16, and the protrusion 51 engages with the protrusion 32 to rotate the hammer 43. A control unit that transmits force to the anvil 27 and controls the electric motor 16 is provided, and the control unit applies a first voltage to the electric motor 16 when the protrusion 51 approaches the protrusion 32, and the hammer When the 43 operates in the direction of the axis A1 and the protrusion 51 gets over the protrusion 32, a second voltage higher than the first voltage is applied to the electric motor 16. [Selection diagram] Fig. 1

Description

  The present invention relates to a striking working machine including a tool holder and an electric motor for rotating the tool holder.

  2. Description of the Related Art Conventionally, an example of a striking working machine including a tool holding unit and an electric motor for rotating the tool holding unit is described in Patent Document 1. The hitting working machine described in Patent Document 1 includes an electric motor, a planetary gear mechanism, a spindle, a hammer as a hitting portion, an anvil as a tool holding portion, a trigger, a control portion, an inverter circuit, and a battery. The inverter circuit has a semiconductor switching element as a switch unit. The output element of the planetary gear mechanism is connected to the spindle. The spindle has a first groove and the hammer has a second groove. Balls are disposed in the first and second grooves. The hammer has a first engagement portion, and the anvil has a second engagement portion. The anvil supports the tool bit. The hammer and the anvil are rotatable about an axis. The hammer is operable axially.

  The signals output from the switch trigger, the current detection circuit, the voltage detection circuit, and the rotation speed detection circuit are input to the control unit. The control unit controls the duty ratio, which is the ON ratio of the semiconductor switching element, to connect and disconnect the battery and the stator of the electric motor.

  The control section of the hitting machine described in Patent Document 1 controls the inverter circuit to rotate the electric motor when an operating force is applied to the trigger. The torque of the electric motor is transmitted to the spindle via the planetary gear mechanism. The rotational force of the spindle is transmitted to the hammer via the ball. The rotational force of the hammer is transmitted to the anvil by the engagement between the first engagement portion and the second engagement portion. The accessory tool rotates and tightens the screw. When the load on the electric motor, that is, the rotational force required to rotate the anvil, increases, the hammer operates in the axial direction, the first engagement portion moves over the second engagement portion, and the first engagement portion separates. The second engaging portion is hit. In this way, the hammer exerts a rotational impact on the anvil.

  The control section of the hitting machine described in Patent Document 1 drives the semiconductor switching element at a high duty ratio, for example, 100% when an operation force is applied to the trigger. Further, the control unit drives the semiconductor switching element at a low duty ratio, for example, 40% before the hammer hits the anvil for the first time. The control unit performs the second and subsequent hits by driving the semiconductor switching element at a low duty ratio.

JP 2014-121765 A

  If the small screw is not tightened at a sufficiently low rotation speed, the small screw may be overtightened and the small screw or the mating member may be damaged. In order to lower the rotation speed, it is necessary to set the voltage applied to the motor low. In this case, however, the torque of the motor is insufficient, and the first engagement portion of the hammer becomes the second engagement portion of the anvil. The inventor of the present application has recognized that there is a case where it is not possible to overcome the problem.

  An object of the present invention is to provide a striking machine capable of performing a tightening operation at a low rotation speed.

  The hitting working machine according to one embodiment includes a tool supporting portion that supports a work tool, a hitting portion that is rotatable about an axis and is operable in the axial direction with respect to the tool supporting portion, An electric motor for rotating a part, a first engaging part provided on the hitting part, and a plurality of second members provided on the tool supporting part and capable of engaging with and getting over the first engaging part. Wherein the first engaging portion is engaged with one of the plurality of second engaging portions to transmit a rotational force of the hitting portion to the tool supporting portion. When the rotational force required to rotate the tool supporting portion increases and the impact portion operates in the axial direction, the first engaging portion engages the second engaging portion engaged with the first engaging portion. The electric motor hits the second engaging portion different from the second engaging portion that has climbed over, and A control unit for controlling, the control unit applies a first voltage to the electric motor when the first engagement portion approaches the second engagement portion, and the first engagement portion When the vehicle gets over the second engagement portion, a second voltage higher than the first voltage is applied to the electric motor.

  According to the impact working machine of one embodiment, it is possible to perform the tightening at a low rotation speed.

It is one embodiment of the impact working machine of this invention, and is a front sectional view which shows the internal structure of a housing. It is the partial front view which attached the storage battery to the striking work machine. FIG. 4 is a perspective view showing an assembled state of a spindle, a hammer, and an anvil used for the impact working machine. It is a block diagram which shows the control system of a striking work machine. 5 is a flowchart illustrating a control example performed by a control unit. 6 is a flowchart showing the details of the low load control shown in FIG. It is an example of a time chart corresponding to low load control.

  Hereinafter, an embodiment of a striking machine according to the present invention will be described with reference to the drawings.

  The impact working machine 10 shown in FIGS. 1 and 2 is an impact driver used for rotating and tightening a screw member to fix it to wood or concrete as a mating member and for loosening the screw member. The impact working machine 10 has a hollow housing 11. The housing 11 includes a motor case 12 and a grip 14 connected to the motor case 12. A hammer case 13 is fixed to the motor case 12, and a grip 14 is provided with a mounting portion 15.

  An electric motor 16 is provided in the motor case 12. The electric motor 16 includes a stator 20 as an armature and a rotor 21 as a field. The stator 20 is provided in the motor case 12 so as not to rotate. The stator 20 includes a stator core 22 and three coils 23U, 23V, and 23W wound around the stator core 22 and supplied with current. ing.

  The rotor 21 includes an output shaft 17, a rotor core 21A fixed to the output shaft 17, and a plurality of permanent magnets 24 arranged along the rotation direction of the rotor core 21A. The output shaft 17 is rotatably supported by two bearings 18 and 19. When a current is supplied to the three coils 23U, 23V, 23W, a rotating magnetic field is formed, and the rotor 21 rotates. In the plurality of permanent magnets 24, permanent magnets 24 having different polarities are alternately arranged along the rotation direction.

  The electric motor 16 is a brushless electric motor that does not use a brush through which current flows. The electric motor 16 changes the direction of rotation of the rotor 21 by switching the direction of current supplied to the three coils 23U, 23V, and 23W. Can switch.

  A partition 25 is provided in the housing 11 to partition the inside of the motor case 12 and the inside of the hammer case 13. The partition 25 is attached so as not to rotate with respect to the housing 11. The partition wall 25 supports the bearing 19, and the motor case 12 supports the bearing 18. The rotor 21 is rotatable about the axis A1.

  The annular hammer case 13 has a shaft hole 26, and an anvil 27 rotatably supported by a cylindrical sleeve 30 is disposed in the shaft hole 26. The anvil 27 is made of metal and is rotatable about the axis A1. The anvil 27 is provided from the inside of the hammer case 13 to the outside of the motor case 12, and the anvil 27 is provided with a tool holding hole 28. The tool holding hole 28 is opened outside the motor case 12. An operator attaches and detaches a driver bit 29 as a work tool to and from the tool holding hole 28.

  A support shaft 31 is provided on the anvil 27 concentrically with the tool holding hole 28. The support shaft 31 is arranged in the hammer case 13. Further, on the outer peripheral surface of the anvil 27, a plurality of protrusions 32 are provided at positions arranged in the hammer case 13. Specifically, the three projections 32 are arranged at equal intervals in the rotation direction of the anvil 27, that is, at intervals of 120 degrees. The three protrusions 32 protrude radially from the outer peripheral surface of the anvil 27 as shown in FIGS. The three projections 32 have a first side surface and a second side surface that are parallel to each other. The first side surface and the second side surface are arranged along the radial direction of the anvil 27. The width of the projection 32 alone in the rotation direction of the anvil 27 is constant in the radial direction of the anvil 27.

  On the other hand, a reduction gear 33 is provided in the hammer case 13. The speed reducer 33 is disposed between the bearing 19 and the anvil 27 in a direction along the axis A1. The speed reducer 33 is a power transmission device that transmits the rotational force of the electric motor 16 to the anvil 27, and the speed reducer 33 is configured by a single pinion type planetary gear mechanism.

  The speed reducer 33 rotates a sun gear 34 disposed concentrically with the output shaft 17, a ring gear 35 provided to surround the outer peripheral side of the sun gear 34, and a plurality of pinion gears 36 meshed with the sun gear 34 and the ring gear 35. And a carrier 37 supported revolvably. The sun gear 34 is formed on the outer peripheral surface of the intermediate shaft 38, and the intermediate shaft 38 rotates together with the output shaft 17. The ring gear 35 is fixed to the partition 25 and does not rotate. The carrier 37 is rotatably supported by a bearing 39. The bearing 39 is supported by the partition 25. The carrier 37 is annular.

  Further, a spindle 40 that rotates integrally with the carrier 37 about the axis A1 is provided in the hammer case 13. The spindle 40 is made of metal and is arranged between the anvil 27 and the bearing 39 in a direction along the axis A1. A support hole 41 is formed at an end of the spindle 40 in the direction of the axis A1. The support shaft 31 is inserted into the support hole 41, and the spindle 40 and the anvil 27 can rotate relative to each other.

  Two cam grooves 42 are provided on the outer peripheral surface of the spindle 40. The two cam grooves 42 are arranged in different ranges in the rotation direction of the spindle 40. In addition, a metal hammer 43 is housed in the hammer case 13. The hammer 43 is annular and has a shaft hole 44. The spindle 40 is disposed in the shaft hole 44. The hammer 43 is arranged between the speed reducer 33 and the anvil 27 in a direction along the axis A1. The hammer 43 is rotatable with respect to the spindle 40 and is operable with respect to the anvil 27 in a direction along the axis A1.

  The hammer 43 has an outer cylinder part 45 and an inner cylinder part 80, and the outer cylinder part 45 is arranged outside the inner cylinder part 80. Two cam grooves 46 are formed on the inner peripheral surface of the inner cylindrical portion 80. The two cam grooves 46 are arranged in mutually different ranges in the circumferential direction of the hammer 43.

  One cam groove 47 is held as one set of one cam groove 42 and one cam groove 46. For this reason, the hammer 43 can move in the direction along the axis A1 within a range where the cam ball 47 can roll with respect to the spindle 40 and the anvil 27. Further, the hammer 43 is rotatable with respect to the spindle 40 within a range where the cam ball 47 can roll.

  Further, the hammer 43 has a holding groove 48 formed between the outer tube 45 and the inner tube 80. The holding groove 48 is opened toward the speed reducer 33. The holding groove 48 is provided annularly around the axis A1. Further, a spring 49 is arranged in the holding groove 48. The spring 49 is made of metal and receives a compressive load to generate a repulsive force. Further, an annular plate 50 is attached to the carrier 37, and the end of the spring 49 is in contact with the plate 50. The spring 49 is disposed between the plate 50 and the hammer 43 in a state where a load in a direction along the axis A1 is applied. The pressing force of the spring 49 is applied to the hammer 43, and the hammer 43 is pressed in a direction along the axis A1 so as to approach the anvil 27.

  Further, a protrusion 51 is provided on the hammer 43. The protrusion 51 protrudes in the direction of the axis A1 from the end of the hammer 43 closest to the anvil 27 in the direction of the axis A1. A plurality of, for example, three projections 51 are provided at equal angular intervals in the rotation direction of the hammer 43. That is, the three protrusions 51 are arranged at an interval of 120 degrees from each other. In the radial direction of the hammer 43, the range where the three protrusions 51 are arranged overlaps the range where the three protrusions 32 are arranged. The three protrusions 51 have a triangular shape when viewed from the end face of the hammer 43, and one of the vertices is arranged at the inner peripheral end of each protrusion 51. That is, each projection 51 has a first side surface and a second side surface corresponding to two sides of the triangle.

  Next, a control system of the electric motor 16 in the striking machine 10 will be described with reference to FIGS. A power supply unit 52 that is attached to and detached from the mounting unit 15 is provided. The main body side terminal 53 is provided on the mounting portion 15. The power supply unit 52 has a housing case 52A and a plurality of battery cells 52B housed in the housing case 52A. The battery cell 52B is a secondary battery that can be charged and discharged, and the battery cell 52B can use a lithium ion battery, a nickel hydride battery, a lithium ion polymer battery, and a nickel cadmium battery. The power supply unit 52 is a DC power supply. The power supply unit 52 has a battery-side terminal 54 connected to the electrode of the battery cell 52B. When the power supply unit 52 is attached to the mounting unit 15, the body-side terminal 53 and the battery-side terminal 54 are connected.

  An inverter circuit 55 is provided on a path for supplying a current from the power supply unit 52 to the electric motor 16. The inverter circuit 55 includes six switching elements Q1 to Q6 formed of FETs (Field effect transistors) connected in a three-phase bridge format. Switching elements Q1 to Q3 are connected to the positive electrode side of power supply unit 52, respectively, and switching elements Q4 to Q6 are connected to the negative electrode side of power supply unit 52, respectively. An inverter circuit board 56 is provided between the bearing 18 and the electric motor 16, and the inverter circuit 55 is provided on the inverter circuit board 56.

  Further, a rotor position detection sensor 57 for detecting the rotational position of the rotor 21 is provided on the inverter circuit board 56. The rotor position detection sensor 57 is configured by a Hall IC, and three rotor position detection sensors 57 are arranged at predetermined intervals in the rotation direction of the rotor 21 with respect to the inverter circuit board 56, for example, at every 60 degrees. Have been. The three rotor position detection sensors 57 each detect a magnetic field formed by the permanent magnet 24 and output a signal corresponding to the detection result.

  Further, a control circuit board 58 is provided in the mounting section 15. The motor control unit 59 is provided on the control circuit board 58. The motor control unit 59 includes a calculation unit 60, a control signal output circuit 61, a motor current detection circuit 62, a battery voltage detection circuit 63, a rotor position detection circuit 64, a motor rotation speed detection circuit 65, a control circuit voltage A detection circuit 66, a switch operation detection circuit 67, and an applied voltage setting circuit 68 are provided.

  The signal output from the rotor position detection sensor 57 is input to a rotor position detection circuit 64, which detects the rotational phase of the rotor 21. The signal output from the rotor position detection circuit 64 is Is input to

  The arithmetic unit 60 outputs a drive signal to the inverter circuit 55 based on the processing program and data, a ROM (Read Only Memory) for storing the processing program and control data, and temporarily stores the data. And a RAM (Random Access Memory).

  A resistor Rs is arranged in a path for supplying power from the power supply unit 52 to the inverter circuit 55, and the motor current detection circuit 62 detects a current value supplied to the electric motor 16 from a voltage drop of the resistance Rs, and detects the value. The signal is output to the arithmetic unit 60. Battery voltage detection circuit 63 detects a voltage supplied from power supply unit 52 to inverter circuit 55, and outputs a detection signal to arithmetic unit 60.

  The rotor position detection circuit 64 receives an output signal of each rotor position detection sensor 57 and outputs a position signal of the rotor 21 to the calculation unit 60 and the motor speed detection circuit 65. The motor rotation speed detection circuit 65 detects the rotation speed of the rotor 21 from the input position signal, and outputs the detection result to the calculation unit 60.

  The voltage of the power supply unit 52 is supplied to the entire motor control unit 59 at a predetermined voltage value via a control circuit voltage supply circuit 69. Further, the control circuit voltage detection circuit 66 detects the voltage of the power supply unit 52 supplied to the motor control unit 59 via the control circuit voltage supply circuit 69, and outputs the detection result to the calculation unit 60.

  A tactile switch 71 is provided on the outer surface of the mounting unit 15. The operator can operate the tactile switch 71 to select any one of a plurality of modes, for example, a low speed mode, a medium speed mode, and a high speed mode. The mode selected by operating the tactile switch 71 is detected by the switch operation detection circuit 67, and a signal output from the switch operation detection circuit 67 is input to the arithmetic unit 60.

  The motor control unit 59 can set the target rotation speed of the electric motor 16 according to the selected mode. The target rotation speed is the rotation speed of the rotor 21 per unit time. The target rotation speed set by the motor control unit 59 in the medium speed mode is higher than the target rotation speed set in the low speed mode and lower than the target rotation speed set in the high speed mode. Further, the applied voltage setting circuit 68 sets a voltage to be applied to the electric motor 16 according to the selected mode, and inputs a signal to the arithmetic unit 60.

  Further, a rotation direction switch 72 is provided, and the operator operates the rotation direction switch 72 to switch the rotation direction of the electric motor 16. The signal output from the rotation direction switch 72 is input to the calculation unit 60. A trigger 73 and a DC speed control switch 74 are provided on the grip 14. The DC speed control switch 74 turns on when an operation force is applied to the trigger 73, and turns off when the operation force on the trigger 73 is released. The DC speed control switch 74 detects the operation amount of the trigger 73 and outputs a signal corresponding to the operation amount. A signal for turning on or off the DC speed control switch 74 and a signal corresponding to the operation amount of the trigger 73 are input to the calculation unit 60.

  The operation unit 60 determines the direction of the current supplied to the coils 23U, 23V, and 23W of the electric motor 16 and the ON / OFF of the switching elements Q1 to Q6 of the inverter circuit 55 based on signals input from various circuits and various switches. An off timing and a duty ratio, which is an on ratio of the switching elements Q1 to Q6, are obtained, and the signal is output to the control signal output circuit 61.

  When the DC speed control switch 74 is turned on by operating the trigger 73, the arithmetic unit 60 alternately turns on and off predetermined switching elements Q1 to Q3 based on the position detection signal of the rotor position detection circuit 64, respectively. A drive signal for executing switching control, a pulse width modulation (PWM) signal for switching control of each of predetermined switching elements Q4 to Q6 are formed, and the drive signal and the pulse width modulation signal are controlled. The signal is output to the signal output circuit 61.

  In addition, the calculation unit 60 can determine whether the operator has selected one of the low-speed mode, the medium-speed mode, and the high-speed mode according to the operation amount of the trigger 73 detected by the DC speed control switch 74, for example. It is.

  The control signal output circuit 61 outputs a switching element driving signal to the gate of the switching element Q1, outputs a switching element driving signal to the gate of the switching element Q2, and outputs a switching element driving signal to the gate of the switching element Q3 based on the driving signal from the arithmetic unit 60. A switching element drive signal is output to the gate, a pulse width modulation signal is output to the gate of switching element Q4, a pulse width modulation signal is output to the gate of switching element Q5, and a pulse width modulation signal is output to the gate of switching element Q6. I do. That is, the three switching elements Q1 to Q3 are separately turned on and off by the switching element drive signal, and the three switching elements Q4 to Q6 are separately turned on and off by the pulse width modulation signal. A certain duty ratio is controlled.

  With this control, the coils 23U, 23V, and 23W are energized alternately in a predetermined energizing direction, a predetermined energizing timing, and a predetermined period, and the rotor 21 is rotated in the target rotation direction and the target rotation speed. You. The target rotation direction can be set by the operator operating the rotation direction switch 72, and the target rotation speed can be set by the operator operating the tactile switch 71. Further, the processing unit 60 can set a target rotation speed according to the operation amount of the trigger 73 by processing a signal output from the DC speed control switch 74. As an example, as the operation amount of the trigger 73 increases, the target rotation speed increases.

  According to the above control, each drain or each source of the six switching elements Q1 to Q6 is separately connected or cut off to the star-connected coils 23U, 23V, and 23W. The voltage applied to the inverter circuit 55 is supplied to the coil 23U as a voltage Vu corresponding to the U phase, supplied to the coil 23V as a voltage Vv corresponding to the V phase, and supplied to the coil 23W as a voltage Vw corresponding to the W phase. Is done. Further, the arithmetic unit 60 changes the duty ratio according to the target rotation speed.

  When the motor control unit 59 selects the mode according to the operation amount of the trigger 73, the motor control unit 59 sets the target rotation speed according to the operation amount of the trigger 73. Note that the range of the target rotation speed differs depending on each mode. The range of the target rotation speed in the medium speed mode is greater than the maximum value of the target rotation speed in the low speed mode and less than the minimum value of the target rotation speed in the high speed mode.

  When the motor control unit 59 sets the target rotation speed of the rotor 21 according to the mode selected by operating the tactile switch 71, as an example, the motor control unit 59 sets the target rotation speed in the high-speed mode to 23,000 rpm, and sets the target rotation speed in the medium-speed mode. The target speed can be set to 14,000 rpm and the target speed in low-speed mode can be set to 4,000 rpm.

  Further, the motor control unit 59 detects the actual rotation speed of the rotor 21 based on a signal input from the motor rotation speed detection circuit 65. Then, the motor control unit 59 controls the duty ratio of the pulse width modulation signal, and performs feedback control so that the actual rotation speed of the rotor 21 approaches the target rotation speed. When the operation of the trigger 73 is released and the DC speed control switch 74 is turned off, the switching elements Q1 to Q6 of the inverter circuit 55 are always turned off, current is not supplied to the coils 23U, 23V and 23W, and the rotor 21 is turned off. Stop.

  Further, a display unit 70 is provided on the housing 11 or the mounting unit 15, and the display unit 70 is configured by a liquid crystal display or a lamp. A display signal is output from the motor control unit 59 to the display unit 70. The operator can visually check the display unit 70 to check the mode for controlling the electric motor 16, the actual rotation speed of the rotor 21, and the voltage of the power supply unit 52.

  Next, an example of use of the striking machine 10 will be described. When the rotor 21 of the electric motor 16 rotates, the torque of the output shaft 17 is transmitted to the sun gear 34 of the speed reducer 33. When the rotational force is transmitted to the sun gear 34, the ring gear 35 becomes a reaction element, and the carrier 37 becomes an output element. That is, when the rotational force of the sun gear 34 is transmitted to the carrier 37, the rotational speed of the carrier 37 is reduced with respect to the rotational speed of the sun gear 34, so that the rotational force is amplified. Note that the speed reducer 33 has a constant speed ratio between the sun gear 34 as an input element and the carrier 37 as an output element, and cannot change the speed ratio.

  When the rotational force is transmitted to the carrier 37, the spindle 40 rotates together with the carrier 37, and the rotational force of the spindle 40 is transmitted to the hammer 43 via the cam ball 47. Then, the protrusion 51 and the protrusion 32 are engaged with each other before the rotation of the hammer 43 by 1/3 of a rotation, and the rotational force of the hammer 43 is transmitted to the anvil 27. Then, the hammer 43 and the anvil 27 rotate integrally, and the rotational force of the anvil 27 is transmitted to the object via the driver bit 29, and the screw member is tightened.

  Thereafter, when the screw member is tightened and the rotational force required to rotate the anvil 27 increases, the rotational speed of the spindle 40 exceeds the rotational speed of the hammer 43, and the spindle 40 rotates with respect to the hammer 43. I do. The rotational force required to rotate the anvil 27 increases as the thickness or length of the screw member increases. When the spindle 40 rotates with respect to the hammer 43, a reaction force generated at a contact surface between the cam ball 47 and the cam groove 46 causes the hammer 43 to move away from the anvil 27 along the axis A <b> 1 against the pressing force of the spring 49. Operate in the wrong direction. Actuation of the hammer 43 in a direction away from the anvil 27 is called retreat. When the hammer 43 retreats, the compressive load applied to the spring 49 increases, and the repulsive force of the spring 49 increases.

  When the hammer 43 retreats and the projection 51 separates from the projection 32, the rotational force of the hammer 43 is not transmitted to the anvil 27 and the projection 51 climbs over the projection 32. At the time when the projection 51 has climbed over the projection 32, the pressing force applied by the spring 49 to the hammer 43 exceeds the force in the direction for retracting the hammer 43. Then, as the cam ball 47 rolls along the cam grooves 42 and 46, the hammer 43 rotates with respect to the spindle 40, and the hammer 43 operates in a direction approaching the anvil 27. Actuation of the hammer 43 in a direction approaching the anvil 27 is referred to as forward movement. Thereafter, the protrusion 51 of the hammer 43 collides with the protrusion 32 of the anvil 27, and a striking force is applied to the anvil 27 in the rotational direction.

  Thereafter, while the rotor 21 is rotating, the above operation is repeated, and the tightening operation of the screw member by the hitting machine 10 is continued. When the rotation direction of the rotor 21 of the electric motor 16 is opposite to the case where the screw member is tightened, the screw member is loosened.

  An example of the control performed by the motor control unit 59 will be described with reference to the flowchart in FIG. In step S10, the motor control unit 59 determines whether the low speed mode is selected. For example, when the operation amount of the trigger 73 exceeds a predetermined amount, the motor control unit 59 determines No in step S10. If No is determined in step S10, the motor control unit 59 performs normal control in step S11, and proceeds to step S10. The normal control is, for example, the following first normal control or second normal control.

  The first normal control is a control for fixing the duty ratio. The duty ratio fixed by the first normal control is a value according to the rotational force of the hammer 43 that allows the protrusion 51 to get over the protrusion 32. The duty ratio when the high-speed mode is selected is higher than the duty ratio when the medium-speed mode is selected.

  The second normal control is a control for fixing the rotation speed of the electric motor 16. The motor control unit 59 sets the target rotation speed of the electric motor 16 to a high rotation speed, and performs feedback control to bring the actual rotation speed of the electric motor 16 closer to the target rotation speed. In the feedback control, the duty ratio is controlled by PID (Proportional Integral Differential). The target rotation speed when the high speed mode is selected is higher than the target rotation speed when the medium speed mode is selected. The high rotation speed is higher than the rotation speed selected in the constant speed control. The rotation speed selected in the constant speed control will be described later.

  On the other hand, if the operation amount of the trigger 73 is equal to or less than the predetermined amount at the time of the determination in step 10, the motor control unit 59 determines Yes in step S10.

  If the determination is Yes in step S10, the motor control unit 59 performs control to fix the duty ratio in step S12. The fixed first duty ratio is, for example, 5%.

  In step S13 following step S12, the motor control unit 59 determines whether the load on the electric motor 16 has increased. As an example, when the current value applied to the electric motor 16 increases or the actual number of revolutions of the electric motor 16 decreases, the motor control unit 59 determines Yes in step S13 and sets the constant speed in step S14. Perform control. The constant speed control is a control for keeping the target rotation speed of the electric motor 16 constant.

  When the motor control section 59 performs the constant speed control, the inverter circuit 55 is controlled at a second duty ratio larger than the first duty ratio. The second duty ratio is determined by the rotational force of the hammer 43 that allows the protrusion 51 to get over the protrusion 32 when the protrusion 51 engages with the protrusion 32 and the load on the electric motor 16 increases. It is a corresponding value. The motor control unit 59 increases the duty ratio for controlling the inverter circuit 55 from 5% to 20%, for example.

  If the motor control unit 59 determines No in step S13, the process proceeds to step S10. The target rotation speed set by the motor control unit 59 in the normal control in step S11 is higher than the target rotation speed set in accordance with the operation amount of the trigger 73 when the motor control unit 59 determines Yes in step S13. .

  In step S15 following step S14, the motor control unit 59 determines whether the hammer 43 has hit the anvil 27. If the motor controller 59 determines No in step S15, the motor controller 59 determines in step S16 whether the load on the electric motor 16 has decreased. The motor control unit 59 proceeds to step S15 when determining No in step S16, and proceeds to step S10 when determining Yes in step S16.

  If the determination is Yes in step S15, the motor control unit 59 performs "low speed mode hit control" in step S17, and proceeds to step S10.

  FIG. 6 shows the contents of the “low speed mode impact control” performed by the motor control unit 59. The motor control unit 59 sets a hitting cycle in step S20 and starts a timer. The striking cycle set by the motor control unit 59 is, for example, from the time when the hammer 43 starts operating in the direction of the axis A1 with respect to the anvil 27 in a state where the protrusion 51 is engaged with the protrusion 32. After the hammer 43 hits the anvil 27 over the protrusion 32, the target time until the hammer 43 starts operating in the direction of the axis A1 with respect to the anvil 27 with the protrusion 51 engaged with the protrusion 32. is there. The motor control unit 59 stores 250 ms as an example of the target time.

  The motor control unit 59 determines that the hammer 43 has started to operate in the direction of the axis A1 with respect to the anvil 27 in the state where the protrusion 51 is engaged with the protrusion 32, and reports that the actual rotation speed and the current value of the electric motor 16 are correct. It can be determined from the above.

  In step S21, the motor control unit 59 further sets the duty ratio for controlling the inverter circuit 55 to the first duty ratio. In step S22, the motor control unit 59 determines whether the actual elapsed time from when the timer started has reached the target time.

  When determining No in step S22, the motor control unit 59 repeats the determination in step S22. If the determination in step S22 is Yes, the motor control unit 59 determines in step S23 whether the low-speed mode is selected. The determination in step S23 is the same as the determination in step S10.

  If No is determined in step S23, the motor control unit 59 performs the process of step S24, and ends the control of FIG. The processing in step S24 is the same as the processing in step S11.

  If the determination is Yes in step S23, the motor control unit 59 sets the striking cycle in step S25 and starts the timer. The process of step S25 performed by the motor control unit 59 is the same as the process of step S20. In step S26, the motor control unit 59 sets the duty ratio for controlling the inverter circuit 55 to the second duty ratio. The second duty ratio is such that when the protrusion 51 engages with the protrusion 32 and the load on the electric motor 16 increases, the protrusion 51 rides over the protrusion 32 and the hammer 43 strikes the anvil 27. Is a possible value.

  In step S27, the motor control unit 59 determines whether the protrusion 51 has climbed over the protrusion 32. When the actual rotation speed of the electric motor 16 is equal to or greater than the determination threshold, the motor control unit 59 determines that the protrusion 51 has passed over the protrusion 32. If the actual rotation speed of the electric motor 16 is less than the determination threshold, the motor control unit 59 determines that the protrusion 51 has not passed over the protrusion 32. The motor control unit 59 stores the determination threshold value in advance.

  If the motor control unit 59 determines Yes in step S27, the motor control unit 59 sets the duty ratio for controlling the inverter circuit 55 to the first duty ratio in step S28. The process of step S28 performed by the motor control unit 59 is the same as the process of step S21. In step S29, the motor control unit 59 determines whether the actual elapsed time from step S25 has reached the target time.

  If the determination at step S29 is No, the motor control unit 59 repeats the determination at step S29. If the motor control unit 59 determines Yes in step S29, the process proceeds to step S23.

  When determining No in step S27, the motor control unit 59 determines in step S30 whether the actual elapsed time from step S25 has reached the target time. If No is determined in step S30, the motor control unit 59 determines whether the load on the electric motor 16 is reduced in step S31. The determination in step S31 performed by the motor control unit 59 is the same as the determination in step S16 in FIG.

  If the motor control unit 59 determines No in step S31, the process proceeds to step S27. If the motor control unit 59 determines Yes in step S31, it ends the control in FIG. If the determination is Yes in step S30, the motor control unit 59 displays "error" on the display unit in step S32, and ends the control in FIG. Further, the motor control section 59 ends the high-load control in step S32 and stops the electric motor 16.

  FIG. 7 is an example of a time chart corresponding to the control example of FIG. As the duty ratio, a first duty ratio and a second duty ratio are shown. The determination threshold for the actual rotation speed of the electric motor 16 is a value for determining whether the protrusion 51 has climbed over the protrusion 32.

  Prior to time T1, motor control section 59 controls the duty ratio to the first duty ratio. The motor control unit 59 changes the duty ratio from the first duty ratio to the second duty ratio at time T1, for example, at the time of step S26 in FIG.

  The motor control unit 59 changes the duty ratio from the second duty ratio to the first duty ratio at time T2, for example, when it is determined as Yes in step S27 of FIG. 6 and the process proceeds to step S28.

  The motor control unit 59 sets the duty ratio to the first duty ratio after time T2. The motor control unit 59 changes the duty ratio from the first duty ratio to the second duty ratio at the time T3, for example, when the process proceeds to step S26 via steps S29 and S23. The current value increases and decreases between time T1 and time T2. The actual number of revolutions of the electric motor 16 increases from the time T1, and decreases from the time T2 to the time T3. The elapsed time from time T1 to time T3 is 250 ms as an example.

  Further, the motor control unit 59 performs the same control from time T3 to time T5 via time T4 and from time T1 to time T3. The current value rises and falls between time T3 and time T4. The actual number of revolutions of the electric motor 16 increases from time T3 and decreases between time T4 and time T5.

  Further, the motor control unit 59 performs the same control from time T5 to time T8 through time T6 and time T7, and from time T1 to time T3. The current value rises and falls between time T5 and time T6. The actual number of revolutions of the electric motor 16 increases from time T5, and decreases from time T6 to time T7.

  In the control example of FIG. 6, the motor control unit 59 switches the duty ratio from the first duty ratio to the second duty ratio when the actual elapsed time from when the timer starts reaches the target time. .

  As described above, the motor control unit 59 adjusts the voltage applied to the electric motor 16 by controlling the duty ratio based on the load of the electric motor 16. That is, the voltage applied to the electric motor 16 changes similarly to the duty ratio or the current value shown in FIG.

  As an example, the motor control unit 59 can detect the load on the electric motor 16 based on at least one of a current value supplied to the electric motor 16 and a rotation speed of the electric motor 16. When the value of the current supplied to the electric motor 16 increases, the motor control unit 59 can determine that the load on the electric motor 16 has increased. When the rotation speed of the electric motor decreases, the motor control unit 59 can determine that the load on the electric motor 16 has increased.

  Note that the motor control unit 59 constantly detects the operation amount of the trigger 73, and can determine that the medium speed mode or the high speed mode is selected based on the operation amount of the trigger 73. Therefore, the motor control unit 59 can switch between the low-speed mode impact control and the normal control in a routine different from the routine shown in FIG. Further, it is also possible to switch between low-speed mode hit control and normal control in a routine different from the routine shown in FIG.

  In addition, the motor control unit 59 can perform the control example of FIG. 5 and the control example of FIG. 6 according to the mode selected by operating the tactile switch 71. When the mode is selected by the tactile switch 71, when an operation force is applied to the trigger 73, the motor control unit 59 rotates the electric motor 16. When the operation force on the trigger 73 is released, the motor control unit 59 stops the electric motor 16. The motor control unit 59 controls the rotation speed of the electric motor 16 to a rotation speed according to the mode, regardless of the operation amount of the trigger 73. Then, the motor control unit 59 makes the determination in step S10 and the determination in step S23 based on the mode selected by operating the tactile switch 71 instead of the operation amount of the trigger 73.

  An example of the technical meaning of the items described in the present embodiment is as follows. The striking machine 10 is an example of a striking machine. The anvil 27 is an example of a tool support. The axis A1 is an example of an axis. The hammer 43 is an example of a hitting unit. The electric motor 16 is an example of an electric motor. The protrusion 51 is an example of a first engagement portion. The protrusion 32 is an example of a second engagement portion. The inverter circuit 55 is an example of a switch unit. The motor control unit 59 is an example of a control unit and an example of a load detection unit.

  The control performed by the motor control unit 59 in steps S21 and S28 of the flowchart in FIG. 6 is an example of low-load control. The control performed by the motor control unit 59 in step S26 of the flowchart in FIG. 6 is an example of high load control. The trigger 73 is an example of an operation member.

  The target rotation speed set according to the operation amount of the trigger 73 when the motor control unit 59 determines Yes in step S13 is an example of a first target rotation speed. Further, an example of the first control is that the motor control unit 59 determines Yes in step S13 and sets the target rotation speed according to the operation amount of the trigger 73.

  The target rotation speed set by the motor control unit 59 in step S11 is an example of a second target rotation speed. The motor control unit 59 setting the target rotation speed in step S11 is an example of the second control.

  Furthermore, the motor control unit 59 can distinguish the operation amount of the trigger 73 into a first operation amount and a second operation amount having different operation amounts, but the fixed amount for distinguishing the first operation amount and the second operation amount is different. It is sufficient that the second operation amount is larger than the first operation amount regardless of the presence or absence of a typical threshold value. The target time set by the motor control unit 59 in step S20 is an example of the “target time”. The tactile switch 71 is an example of a mode switching unit. The low speed mode is an example of a mode in which the target rotation speed is the lowest.

  As described above, when the load on the electric motor 16 is low, that is, when the protrusion 51 approaches the protrusion 32, the voltage corresponding to the first duty ratio is applied to the electric motor 16. When the load on the electric motor 16 starts to increase, that is, when the protrusion 51 gets over the protrusion 32, a voltage corresponding to the second duty ratio can be applied to the electric motor 16.

  The hitting machine in the present embodiment has the following features. A tool supporting portion that supports a work tool, a hitting portion that is rotatable about an axis, and is operable in the axial direction with respect to the tool supporting portion, an electric motor that rotates the hitting portion, A striking working machine having a first engaging portion provided on a striking portion, and a plurality of second engaging portions provided on the tool supporting portion and capable of engaging with and overcoming the first engaging portion. Wherein the first engagement portion is engaged with any of the plurality of second engagement portions to transmit the rotational force of the hitting portion to the tool support portion, and the first engagement portion is When the rotational force required to rotate the tool support increases and the striking portion operates in the axial direction, the striking portion rides over the engaged second engaging portion, and the second engaging portion engages the second engaging portion. The voltage applied to the electric motor is controlled by hitting the second engaging portion different from the engaging portion. A switch unit that is turned on and off, and a control unit that controls on and off of the switch unit, wherein the control unit is configured to control when the first engagement unit approaches the second engagement unit. When a first voltage is applied to the electric motor with a duty ratio, which is an ON ratio of the switch unit as a first duty ratio, and the first engagement unit gets over the second engagement unit, the duty ratio And a second duty ratio, wherein a second voltage higher than the first voltage is applied to the electric motor.

  It is needless to say that the impact working machine is not limited to the above embodiment, but can be variously modified without departing from the gist thereof. For example, at least one of the control unit and the load detection unit may be a single electric component or an electronic component, or may be a unit having a plurality of electric components or a plurality of electronic components. Electrical or electronic components include processors, control circuits, and modules. The control unit and the load detection unit may be the same component, or the control unit and the load detection unit may be separate components.

  The tool support includes a driver bit for tightening a screw as a screw member, and a driver bit having a recess for inserting a head of a bolt as a screw member. Driver bits with recesses are also called sockets or boxes. Further, the power tool includes a structure in which a nut having a female screw is rotated to fix the nut to a bolt having a male screw.

  Further, the power tool includes a drill bit for drilling holes in wood, concrete and the like. The first engagement portion and the second engagement portion engage with each other to transmit a rotational force. The first engagement portion includes a protrusion that protrudes in the axial direction from the hammer or a protrusion that protrudes in the radial direction from the hammer. The second engagement portion includes a protrusion that protrudes in the axial direction from the tool support, or a protrusion that protrudes in the radial direction from the tool support.

  Further, instead of the speed reducer, a speed changer that can change the speed ratio between the input element and the output element stepwise or steplessly can be provided. In this case, a gear ratio change switch is provided on the housing, and the operator operates the gear ratio change switch to change the gear ratio of the transmission.

  Further, the power supply for supplying a current to the electric motor may be an AC power supply in addition to a DC power supply. Further, as the electric motor, an electric motor with a brush can be used instead of the brushless electric motor.

  Further, the operating member includes a lever or switch that can be reciprocated linearly, a knob that can be rotated, and a lever that can be circularly operated within a predetermined angle range. The mode switching section includes a liquid crystal display in addition to a lever, a switch, and a button that are operated by an operation force of an operator.

  DESCRIPTION OF SYMBOLS 10 ... Hitting machine, 16 ... Electric motor, 27 ... Anvil, 32, 51 ... Projection part, 43 ... Hammer, 55 ... Inverter circuit, 59 ... Motor control part, 71 ... Tactile switch, 73 ... Trigger, A1 ... Axis line

Claims (8)

A tool supporting portion that supports a work tool, a hitting portion that is rotatable about an axis, and is operable in the axial direction with respect to the tool supporting portion, an electric motor that rotates the hitting portion, A striking working machine having a first engaging portion provided on a striking portion, and a plurality of second engaging portions provided on the tool supporting portion and capable of engaging with and overcoming the first engaging portion. And
The first engagement portion engages with any of the plurality of second engagement portions to transmit the rotational force of the hitting portion to the tool support portion,
The first engagement portion, when the rotational force required to rotate the tool support portion increases and the impact portion operates in the axial direction, gets over the engaged second engagement portion, And striking the second engaging portion different from the second engaging portion that has passed over,
A control unit for controlling the electric motor is provided,
The control unit includes:
When the first engagement portion approaches the second engagement portion, a first voltage is applied to the electric motor,
A striking work machine configured to apply a second voltage higher than the first voltage to the electric motor when the first engagement portion gets over the second engagement portion. The control unit includes:
From the point in time when the first engagement portion has passed over the second engagement portion, the first engagement portion approaches another second engagement portion, and the first engagement portion separates from the second second engagement portion. A low load control that applies the first voltage to the electric motor before hitting the engagement portion and before the hitting portion operates in the axial direction;
From the time when the hitting portion operates in the axial direction to the time when the first engaging portion crosses another second engaging portion, the second voltage higher than the first voltage is applied to the electric motor. High load control applied to the
The impact working machine according to claim 1, which performs the following. An operating member to which an operator can add and release an operating force is further provided,
The control unit includes:
When the operation amount of the operation member is the first operation amount, first control for setting the rotation speed of the electric motor to a first target rotation speed;
When the operation amount of the operation member is a second operation amount that is larger than the first operation amount, a second operation that sets the rotation speed of the electric motor to a second target rotation speed that is higher than the first target rotation speed. 2 controls,
Can be selected,
The impact working machine according to claim 2, wherein the control unit switches between the low load control and the high load control when the first control is selected.   Based on at least one of the current value supplied to the electric motor or the number of rotations of the electric motor, a load detection unit that detects a rotational force required to rotate the tool support unit is further provided. The impact working machine according to claim 1 or 3. The control unit may be configured such that the first engagement unit engages with the second engagement unit and the first engagement unit engages with the second engagement unit from a time when the hitting unit starts operating in the axial direction. After the second engaging portion has been overcome and the first engaging portion has hit another second engaging portion, a target time is stored until the hitting portion starts operating in the axial direction. Yes,
The control unit is configured such that the first engagement portion engages with the second engagement portion, and the actual elapsed time from the time when the hitting portion starts operating in the axial direction is the target time. 4. The hitting machine according to claim 2, wherein when reached, after the first engaging portion has hit another second engaging portion, the hitting portion is determined to have started operating in the axial direction. 5.   The impact working machine according to any one of claims 2, 3, and 5, wherein the control unit alternately performs the low load control and the high load control.   The controller terminates the high load control and stops the electric motor when the elapsed time reaches the target time in a state where the first engagement portion is engaged with the second engagement portion. 6. The impact working machine according to claim 5, wherein A mode switching unit operated by an operator and capable of selecting any one of a plurality of modes in which the number of rotations of the electric motor is different is provided,
3. The impact working machine according to claim 2, wherein the control unit switches between the low load control and the high load control when the mode in which the number of rotations of the electric motor is lowest is selected.

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