JP2016049603A - Striking work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a striking work machine capable of executing a control according to a work situation.SOLUTION: A striking work machine 10 having a striking mechanism 83 for striking a leading end tool 11 by making use the pressure of a pressure chamber 21 comprises: a pressure sensor 73 for detecting the pressure of the pressure chamber 21; a controller for determining the state of the striking mechanism 83 on the basis of the detection result of the pressure; and a motor control unit 40 for controlling the output of a brushless motor 35 on the basis of the determination result of the controller.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a striking work machine that strikes a tip tool using the pressure of a pressure chamber.

  Japanese Patent Application Laid-Open No. 2004-133867 discloses a striking work machine that strikes a tip tool using the pressure in a pressure chamber. The hitting machine described in Patent Document 1 includes a cylindrical cylinder provided in a housing, an operation member that is housed in a reciprocating manner in the cylinder, a tip tool held in the cylinder, and a reciprocating motion in the cylinder. The striker is operably provided, an intermediate element disposed between the tip tool and the striker in the cylinder, and a pressure chamber formed between the action member and the striker in the cylinder. A breathing hole connected to the pressure chamber is formed in the cylinder. A motor is provided in the housing, and a power conversion mechanism that converts the rotational force of the output shaft of the motor into the reciprocating force of the operating member is provided.

  In the impact working machine described in Patent Document 1, the rotational force of the output shaft of the motor is converted into the reciprocating force of the operating member. When the moving member moves away from the striker, the pressure in the pressure chamber decreases. On the other hand, when the moving member moves in the direction approaching the striker, the pressure in the pressure chamber rises and the striking force passes through the intermediate member. Added to the tool.

JP 2009-113122 A

  The hitting machine described in Patent Document 1 has been desired to be controlled in accordance with the work situation.

  An object of the present invention is to provide a striking work machine capable of executing control according to a work situation.

  The striking work machine of the present invention is a striking work machine provided with a striking mechanism that strikes a tip tool using the pressure in the pressure chamber, and includes a pressure detection unit for detecting the pressure in the pressure chamber, and detection of the pressure. Based on a result, it has the 1st judgment part which judges the state of the hitting mechanism, and the control execution part which performs control based on the judgment result of the 1st judgment part.

  According to the present invention, it is possible to execute the control of the hitting work machine according to the work situation.

It is an example of the hitting | working work machine of this invention, and is front sectional drawing which shows a load state. It is front sectional drawing which shows the striking mechanism of the striking work machine of FIG. It is an example of an impact work machine of the present invention, and is a front sectional view showing an unloaded state. It is front sectional drawing of the striking mechanism of the striking work machine of FIG. It is a plane sectional view of the striking mechanism of FIG. It is a block diagram which shows the control circuit of the impact working machine of this invention. (A), (B) is an expanded sectional view of the pressure sensor used for the striking work machine of the present invention. It is a flowchart explaining the example 1 of control which can be performed with the hitting work machine of the present invention. It is an example of the time chart corresponding to the control example 1. FIG. It is a flowchart explaining the example 2 of control which can be performed with the hitting | working work machine of this invention. It is an example of the time chart corresponding to the control example 2. FIG. It is a flowchart explaining the example 3 of control which can be performed with the hitting | working work machine of this invention.

  Hereinafter, the impact working machine which is an embodiment of the invention is explained in detail based on Drawings 1-5. The striking work machine 10 is a hammer, and the tip tool 11 attached to the striking work machine 10 is used for work for crushing the object and work for crushing the object. Objects to be crushed include concrete and asphalt. Objects to be damped include earth and sand and paving stones. The striking work machine 10 has a cylindrical cylinder housing 12, and a cylindrical cylinder 13 is provided in the cylinder housing 12.

  The cylinder 13 is disposed around the axis A <b> 1, and a cylindrical tool holder 14 is provided concentrically with the cylinder 13. The cylinder 13 and the tool holder 14 do not move in the direction along the axis A1. The tool holder 14 has a small diameter portion 15 and a large diameter portion 16. The small diameter portion 15 is disposed at a position different from the large diameter portion 16 in the direction along the axis A1. The small diameter portion 15 is disposed outside the cylinder housing 12. The inner diameter of the small diameter portion 15 is smaller than the inner diameter of the large diameter portion 16, and the tip tool 11 is attached to and detached from the tool holder 14. The tip tool 11 is integrally formed of metal, for example, iron. A tapered surface 17 that connects the inner surface of the small diameter portion 15 and the inner surface of the large diameter portion 16 is formed in the tool holder 14. The taper surface 17 is inclined in such a direction that the inner diameter decreases as it approaches the inner surface of the small diameter portion 15 from the inner surface of the large diameter portion 16.

  A metal striking force transmission member 18 is provided from the large diameter portion 16 of the tool holder 14 to the inside of the cylinder 13. The striking force transmission member 18 can reciprocate in the direction along the axis A1. A striker 19 that strikes the striking force transmission member 18 is provided in the cylinder 13. The striker 19 is made of metal and can reciprocate in the direction along the axis A1. A piston 20 is disposed in the cylinder 13, and the piston 20 can reciprocate in a direction along the axis A1. The material of the piston 20 is synthetic resin or aluminum. A pressure chamber 21 is formed in the cylinder 13 between the striker 19 and the piston 20. The striker 19 operates according to the pressure change in the pressure chamber 21. Further, a breathing hole 22 and an exhaust hole 23 that penetrate the cylinder 13 in the radial direction and connect to the pressure chamber 21 are provided. The breathing hole 22 and the exhaust hole 23 are arranged at different positions in the direction along the axis A1. The exhaust hole 23 is disposed between the breathing hole 22 and the tool holder 14 in a direction along the axis A1.

  An attachment groove 24 is provided on the outer periphery of the striker 19, and an O-ring 25 is attached to the attachment groove 24. The O-ring 25 is a sealing device integrally formed of synthetic rubber, and the O-ring 25 comes into contact with the inner peripheral surface of the cylinder 13 to form a sealing surface. Further, an attachment groove 26 is provided on the outer periphery of the piston 20, and an O-ring 27 is attached to the attachment groove 26. The O-ring 27 is a sealing device integrally formed of synthetic rubber, and the O-ring 27 comes into contact with the inner peripheral surface of the cylinder 13 to form a seal surface. The two O-rings 25 and 27 hermetically seal the pressure chamber 21.

  On the other hand, a crankcase 28 and a gear case 29 are fixed to the cylinder housing 12. Further, a cover 30 is provided to cover the opening portion above the crankcase 28. Further, a motor housing 31 is attached to the gear case 29. The cylinder housing 12, the crankcase 28, the gear case 29, and the motor housing 31 are fixed to each other, and the striking mechanism housing case 82 is assembled. Furthermore, a grip 32 that connects the motor housing 31 and the crankcase 28 is provided. A trigger 33 is attached to the grip 32, and a power cable 34 is attached to the grip 32.

  A brushless motor 35 is accommodated in the motor housing 31. The brushless motor 35 is a direct current electric motor, and the brushless motor 35 includes a cylindrical stator 36 in which a coil is wound around an iron core, and a rotor 37 disposed inside the stator 36. The rotor 37 includes an output shaft 38, a rotor core 39 fixed to the outer periphery of the output shaft 38, and a permanent magnet attached to the rotor core 39.

  A motor control unit 40 is provided in a space between the motor housing 31 and the grip 32, and a sensor substrate 41 is provided in the motor housing 31. A shaft hole is provided in the sensor substrate 41, and the output shaft 38 is passed through the shaft hole. The sensor substrate 41 is attached to the stator 36 and is provided in the motor housing 31 through the stator 36 so as not to rotate. In the front view of the impact work machine 10, the axis B1 that is the rotation center of the output shaft 38 is orthogonal to the axis A1. Further, the output shaft 38 is rotatably supported by two bearings 42 and 43. An end of the output shaft 38 is disposed in the gear case 29, and a drive gear 44 is provided on the outer peripheral surface of the output shaft 38 at a position disposed in the gear case 29.

  Further, the impact work machine 10 has a power conversion mechanism 45 that converts the rotational force of the output shaft 38 into the reciprocating force of the piston 20. The power conversion mechanism 45 includes a crankshaft 46 and a connecting rod 47. The crankshaft 46 is disposed from the gear case 29 to the crankcase 28. The crankshaft 46 is supported by two bearings 48 and 49 and is rotatable about the axis C1. The axis C1 is parallel to the axis B1 and is orthogonal to the axis A1.

  The crankshaft 46 is parallel to the output shaft 38, and a driven gear 50 provided on the crankshaft 46 is engaged with the drive gear 44. The number of teeth of the driven gear 50 is larger than the number of teeth of the drive gear 44, and the drive gear 44 and the driven gear 50 function as a speed reduction mechanism. That is, when the rotational force of the output shaft 38 is transmitted to the crankshaft 46, the rotational speed of the crankshaft 46 is lower than the rotational speed of the output shaft 38. The crankshaft 46 is provided with a crankpin 51 that is eccentric from the axis C1 that is the rotation center of the crankshaft 46. The crankpin 51 is disposed in the crankcase 28.

  The connecting rod 47 is disposed from the cylinder 13 to the crankcase 28. A first end portion in the length direction of the connecting rod 47 is rotatably connected to the crankpin 51. Further, the second end portion of the connecting rod 47 in the length direction is connected to the piston 20 via a connecting pin 52. The connecting rod 47 can swing around the connecting pin 52. Therefore, when the crankshaft 46 is rotated by the rotational force of the output shaft 38, the crankpin 51 revolves around the axis C1 and the piston 20 reciprocates along the axis A1 in the cylinder 13. The operating force when the piston 20 moves away from the crankshaft 46 is forward power, and the operating force when the piston 20 approaches the crankshaft 46 is return power.

  A position where the piston 20 moves along the axis A1 and is closest to the crankshaft 46 is a top dead center, and a position where the piston 20 is farthest from the crankshaft 46 is a bottom dead center. In the present embodiment, in FIG. 5, the phase in the rotational direction of the crankshaft 46 when the piston 20 is at the top dead center is defined as the reference position G1. In FIG. 5, the crankshaft 46 rotates counterclockwise, and the position of the crankshaft 46 with respect to the reference position G1 is treated as the rotation angle θ.

  Therefore, when the crankshaft 46 rotates once in a predetermined direction with the reference position G1 as 0 degree, that is, rotates 360 degrees, the piston 20 operates from the top dead center toward the bottom dead center, and the bottom dead center. To return to top dead center. That is, the piston 20 reciprocates once in the cylinder 13.

  The striking mechanism 83 is configured by the brushless motor 35, the power conversion mechanism 45, the cylinder 13, the piston 20, the striking element 19, the striking force transmission member 18, and the pressure chamber 21.

  FIG. 6 is a block diagram showing a control circuit of the impact work machine 10. The rotor 37 of the brushless motor 35 rotates with electric power supplied from the AC power supply 84. The impact work machine 10 includes a rotation speed setting dial 53 that sets a target rotation speed of the rotor 37 of the brushless motor 35. The target rotational speed is the rotational speed of the rotor 37 per unit time. The rotation speed setting dial 53 is provided on the cylinder housing 12, the motor housing 31, the grip 32, and the like.

  Further, the stator 36 of the brushless motor 35 includes coils U1, V1, and W1 corresponding to the U phase, V phase, and W phase, and the rotor core 39 of the rotor 37 is spaced apart in the circumferential direction with different polarities 2. Four kinds of permanent magnets 54 are provided, and the permanent magnets 54 of different polarities are alternately arranged. In order to detect the rotational position of the rotor 37, three magnetic sensors 55, 56, and 57 are provided in correspondence with the three-phase coils U1, V1, and W1. The magnetic sensors 55, 56, and 57 are attached to the sensor substrate 41. Each of the magnetic sensors 55, 56, and 57 is a non-contact sensor that detects the magnetic force generated by the four permanent magnets 54, converts the magnetic force into an electric signal, and outputs the electric signal. Hall sensors can be used for the magnetic sensors 55, 56, and 57.

  The impact work machine 10 has an inverter circuit 58 for controlling the current value of the current flowing through each of the coils U1, V1, and W1. The inverter circuit 58 includes a rectifier circuit 59 for rectifying the AC current of the AC power supply 84 into a DC current, and a power factor improving circuit 60 for boosting the voltage of the rectified DC current and supplying the boosted voltage to the inverter circuit 58. , Power is supplied via. The power factor correction circuit 60 includes an integrated circuit 62 that outputs a PWM (abbreviation of Pulse Width Modulation) signal to a transistor 61 composed of a field effect transistor. The power factor correction circuit 60 is an inverter circuit. The harmonic current generated by the 58 switching elements is suppressed to a limit value or less. A noise countermeasure circuit 63 is provided between the AC power supply 84 and the rectifier circuit 59 in order to prevent the noise generated in the inverter circuit 58 from being transmitted to the AC power supply 84.

  The inverter circuit 58 is a three-phase full-bridge inverter circuit, and includes two switching elements Tr1 and Tr2 connected in series, two switching elements Tr3 and Tr4 connected in series, and two switching elements connected in series. The switching elements Tr1, Tr3, Tr5 are connected to the positive output terminal of the power factor improvement circuit 60, and the three switching elements Tr2, Tr4, Tr6 are connected to the power factor improvement circuit 60. Connected to the negative output terminal.

  The three switching elements Tr1, Tr3, Tr5 connected to the positive side of the power factor correction circuit 60 are on the high side, and the three switching elements Tr2, Tr4 connected to the negative side of the power factor improvement circuit 60 , Tr6 are on the low side. One connection terminal of the U-phase coil U1 is connected between the two switching elements Tr1 and Tr2. One connection terminal of the V-phase coil V1 is connected between the two switching elements Tr3 and Tr4. One connection terminal of a W-phase coil W1 is connected between the two switching elements Tr5 and Tr6.

  The other connection terminals of the coils U1, V1, and W1 are connected to each other, and the coils U1, V1, and W1 are star-connected. In addition, the connection system of the coils U1, V1, and W1 may be delta connection. When a control signal is supplied to the gates of the high-side switching element Tr1 and the low-side switching element Tr4, current is supplied to the U-phase and V-phase coils U1 and V1. By adjusting the energization timing and energization ratio of the control signal supplied to each of the switching elements Tr1 to Tr6, the current value supplied to the coils U1, V1, and W1 is controlled. The energization ratio of the control signal supplied to the switching elements Tr1 to Tr6 is called a duty ratio.

  The motor control unit 40 calculates and outputs a control signal for controlling the inverter circuit 58. The motor control unit 40 includes a controller 64, a control signal output circuit 65, a rotor position detection circuit 66, a motor rotation speed detection circuit 67, a motor current detection circuit 68, and an operation switch detection circuit 69. Detection signals from the magnetic sensors 55, 56, and 57 are sent to the rotor position detection circuit 66. The rotor position detection circuit 66 processes a signal indicating the rotational position of the rotor 37. The signal output from the rotor position detection circuit 66 is sent to the controller 64 and the motor rotation number detection circuit 67. The motor rotation speed detection circuit 67 detects the rotation speed of the rotor 37, that is, the motor rotation speed, and the signal output from the motor rotation speed detection circuit 67 is input to the controller 64.

  A current detection resistor 70 is provided in the electric circuit E <b> 1 that supplies power from the AC power supply 84 to the inverter circuit 58. The motor current detection circuit 68 detects the current value supplied to the coils U 1, V 1, W 1 of the stator 36 from the voltage drop of the current detection resistor 70, and outputs a signal corresponding to the detection result to the controller 64.

  The controller 64 includes a microprocessor that processes control signals and a memory, and the memory stores a control program, arithmetic expressions, and data. The controller 64 processes the signal input from the motor rotation speed detection circuit 67 and calculates the actual rotation speed of the rotor 37 and the actual rotation speed per unit time.

  The controller 64 can also process the signal input from the rotor position detection circuit 66 to estimate the rotation angle θ of the crankshaft 46. As described above, the output shaft 38 and the crankshaft 46 are connected via the drive gear 44 and the driven gear 50 so that power can be transmitted. Since the speed reduction ratio of the speed reduction mechanism constituted by the drive gear 44 and the driven gear 50 is constant, the controller 64 determines the rotation angle θ of the crankshaft 46 based on the rotational position of the rotor 37 and the speed reduction ratio of the speed reduction mechanism. Can be estimated. The signal output from the controller 64 is input to the control signal output circuit 65, and the inverter circuit 58 controls the duty ratio of the switching elements Tr1 to Tr6 by the control signal output from the control signal output circuit 65.

  A trigger switch 71 for detecting the operation of the trigger 33 is provided, and a signal output from the trigger switch 71 is input to the operation switch detection circuit 69. When the operator operates the trigger 33 and the trigger switch 71 is turned on or off, an on signal or an off signal output from the operation switch detection circuit 69 is sent to the controller 64. When an ON signal is input to the controller 64, a control signal output from the control signal output circuit 65 is input to the inverter circuit 58, current flows through the coils U1, V1, and W1, and the rotor 37 rotates. The rotation direction of the rotor 37 is one direction and does not reversely rotate.

  The controller 64 performs control to bring the actual rotational speed of the rotor 37 close to the target rotational speed. The actual rotational speed of the rotor 37 is controlled by adjusting the voltages applied to the coils U1, V1, and W1. Specifically, it is performed by controlling the duty ratio, which is the energization ratio applied to the gates of the switching elements Tr1 to Tr6 of the inverter circuit 58, and the controller 64 determines the actual rotational speed of the rotor 37 and the target rotational speed. By increasing / decreasing the duty ratio according to the difference, control is performed so as to approach the actual rotational speed and the target rotational speed.

  Further, a crank position detection sensor 72 is attached to the crankcase 28. The crank position detection sensor 72 is a non-contact sensor that does not contact the crankshaft 46. A signal output from the crank position detection sensor 72 is input to the controller 64 via a signal line, and the controller 64 detects the rotation angle θ of the crankshaft 46 based on the signal from the crank position detection sensor 72. More specifically, the controller 64 can detect the rotation angle θ of the crankshaft 46 relative to the reference position G1 with the phase in the rotation direction of the crankshaft 46 when the piston 20 is at the top dead center as the reference position G1. is there.

  Further, the controller 64 can detect the rotation angle θ per unit time of the crankshaft 46 based on the signal from the crank position detection sensor 72. As the crank position detection sensor 72, for example, a magnetic potentiometer or a magnetic rotary encoder can be used.

  Further, a pressure sensor 73 for detecting the pressure in the pressure chamber 21 is provided, and a signal output from the pressure sensor 73 is input to the controller 64 via a signal line. As the pressure sensor 73, a diaphragm sensor or a piezoresistive sensor can be used. An example of attaching the pressure sensor 73 to the piston 20 will be described with reference to FIGS. The pressure sensor 73 is attached to the piston 20.

  When the material of the piston 20 is a synthetic resin, the pressure sensor 73 is attached to the piston 20 as shown in FIG.

  A sensor accommodating portion 74 is provided in the piston 20, and the pressure sensor 73 is accommodated in the sensor accommodating portion 74. The piston 20 includes an end surface 20A that receives the pressure of the pressure chamber 21, and the sensor housing portion 74 is a recess that opens to the end surface 20A. The piston 20 is provided with a stopper 75, and the stopper 75 is applied to the protrusion 76 of the pressure sensor 73, thereby preventing the pressure sensor 73 from coming out of the sensor housing portion 74.

  On the other hand, when the material of the piston 20 is aluminum, the pressure sensor 73 is attached to the piston 20 as shown in FIG. The piston 20 is provided with a sensor housing portion 77 and a female screw hole 78 connected to the sensor housing portion 77. The pressure sensor 73 includes a male screw shaft 79, the male screw shaft 79 is screwed into the female screw hole 78, and the pressure sensor 73 is fixed to the piston 20 while being housed in the sensor housing portion 77. . The sensor accommodating portion 77 is a recess opened in the end face 20A. Even when the pressure sensor 73 is attached to the piston 20 by any of the methods shown in FIGS. 7A and 7B, the signal line that sends the signal output from the pressure sensor 73 to the controller 64 is operated by the piston 20. However, it has a length and flexibility not to break.

  Further, a striker sensor 80 for detecting the position of the striker 19 in a direction along the axis A1 is provided. The striker sensor 80 is attached to the cylinder 13, and a signal output from the striker sensor 80 is input to the controller 64 through a signal line. As the striker sensor 80, a proximity sensor or a photoelectric sensor using magnetism can be used.

  Further, an output portion 81 is provided on the cylinder housing 12, the cover 30, or the grip 32. The output unit 81 includes a liquid crystal display, a speaker, and a lamp. The output unit 81 outputs the state of the hitting work machine 10 and notifies the worker. The state of the hitting work machine 10 includes a target rotation speed, an actual rotation speed, an abnormality, and the like.

  An example of using the impact work machine 10 will be described. When the operator presses the tip tool 11 against the object, the striking force transmission member 18 is pushed by the tip tool 11, and the striking force transmission member 18 moves away from the tapered surface 17 as shown in FIGS. 1 and 2. Further, the striker 19 is pushed by the strike force transmission member 18 and stops at a first predetermined position in the direction along the axis A1. The first predetermined position is the position of the striker 19 in the direction along the axis A1 where the exhaust hole 23 is opened as shown in FIGS.

  When the power cable 34 is connected to the AC power supply 84 and the operator applies an operating force to the trigger 33, the trigger switch 71 is turned on. Then, the switching elements Tr1 to Tr6 of the inverter circuit 58 are turned on / off by a signal output from the control signal output circuit 65. As a result, electric power is supplied to the brushless motor 35 and the rotor 37 rotates. The motor control unit 40 sets the duty ratio in the inverter circuit 58 based on the target rotation speed set by operating the rotation speed setting dial 53.

  The rotational force of the output shaft 38 of the brushless motor 35 is transmitted to the crankshaft 46 via the drive gear 44 and the driven gear 50. The rotational force of the crankshaft 46 is converted into the reciprocating force of the piston 20 by the connecting rod 47, and the piston 20 reciprocates along the axis A1.

  When the piston 20 moves toward the crankshaft 46, the air is sucked into the pressure chamber 21 from the breathing hole 22, the pressure in the pressure chamber 21 decreases, and the striker 19 moves away from the striking force transmission member 18. Move with. Then, after the piston 20 reaches the top dead center, when the piston 20 moves from the top dead center toward the bottom dead center, the pressure in the pressure chamber 21 increases. Then, the striker 19 moves in a direction away from the crankshaft 46 due to the pressure in the pressure chamber 21, and strikes the striking force transmission member 18.

  A part of the air in the pressure chamber 21 passes through the breathing hole 22 and is discharged to the outside of the pressure chamber 21. The striking force applied to the striking force transmission member 18 is transmitted to the object via the tip tool 11. Thereafter, while the output shaft 38 of the brushless motor 35 is rotating, the piston 20 reciprocates in the cylinder 13 and the striking element 19 applies a striking force intermittently to the striking force transmission member 18.

  In the present embodiment, the motor control unit 40 determines the state of the hitting work machine 10 based on a signal input to the controller 64 and data stored in advance in the memory of the controller 64, and various types based on the determination result. Can be controlled. Hereinafter, control examples that can be executed by the impact work machine 10 will be sequentially described.

(Control example 1)
FIG. 8 is a flowchart for explaining the control example 1. The flowchart of FIG. 8 is started when the power cable 34 is connected to the AC power supply 84 and the motor control unit 40 is activated. First, in step S1, the motor control unit 40 determines whether or not the pressure in the pressure chamber 21 is negative. For example, the pressure in the pressure chamber 21 when the impact working machine 10 is used in a high temperature environment is higher than the pressure in the pressure chamber 21 when used in a normal temperature environment. Then, the air in the pressure chamber 21 leaks from the seal surface to the outside of the pressure chamber 21. Thereafter, the temperature of the use environment decreases, and a phenomenon occurs in which the inside of the striking mechanism housing case 82, particularly, the pressure chamber 21 becomes negative pressure.

  When the pressure chamber 21 becomes negative pressure, a phenomenon occurs in which the responsiveness in which the striker 19 moves following the piston 20 decreases in the stroke in which the piston 20 moves toward the top dead center. When the responsiveness to which the striker 19 moves decreases, the impact force applied to the striker 19 decreases. Therefore, when the motor control unit 40 determines Yes in step S1, the process proceeds to step S2, executes control for displaying an abnormality in the output unit 81, and returns to step S1. For example, “abnormal” can be displayed on the liquid crystal display. Alternatively, the operator is notified of the abnormality by turning on the lamp or by outputting sound from the speaker.

  When an abnormality is displayed on the output unit 81, the operator can release the negative pressure state inside the striking mechanism housing case 82 by removing the cover 30. After that, when performing the striking work with the cover 30 closed, the responsiveness of the striking element 19 moving toward the crankshaft 46 can be improved.

  On the other hand, if the motor control unit 40 determines No in step S1, it proceeds to step S3 and determines whether the trigger switch 71 is turned on. If the motor control unit 40 determines No in step S3, it returns to step S1, and if it determines Yes in step S3, it proceeds to step S4 to flow the current of the AC power supply 84 to the coils U1, V1, W1 and to operate the brushless motor 35. Rotate. The set rotational speed used when rotating the brushless motor 35 in step S4 is lower than the target rotational speed set by operating the rotational speed setting dial 53. For example, when the target rotational speed is 3,000 rpm, the set rotational speed used in step S4 is 2,700 rpm, which is lower than the target rotational speed.

  In step S5 following step S4, the motor control unit 40 determines whether or not the pressure in the pressure chamber 21 is equal to or less than the threshold value for two consecutive cycles. Here, the cycle in the present embodiment is the position of the piston 20 or the rotation angle θ of the crankshaft 46. One cycle of the piston 20 is a stroke until the piston 20 moves toward the bottom dead center with the top dead center as an initial position and returns to the top dead center through the bottom dead center. One cycle of the crankshaft 46 is represented by a rotation angle θ from the reference position G1 of the crankshaft 46 corresponding to the top dead center of the piston 20. That is, the rotation angle θ corresponding to the period from when the rotation angle of the crankshaft 46 is 0 degrees to when the piston 20 moves toward the bottom dead center and returns to the top dead center through the bottom dead center, that is, 360 degrees. Is one cycle. The control example 1 will be described using the cycle of the crankshaft 46.

  Both the cycle of the piston 20 and the cycle of the crankshaft 46 are detected from signals of the crank position detection sensor 72 or the rotor position detection circuit 66. The threshold value is a reference value for determining whether the state of the hitting work machine 10 is a loaded state or a no-load state. The threshold value used in step S5 is obtained by experiments and simulations and is stored in the memory of the controller 64.

  When the tip tool 11 is pressed against the object, the striking force transmission member 18 moves away from the tapered surface 17. Therefore, the O-ring 25 attached to the striker 19 is located between the exhaust hole 23 and the breathing hole 22 as shown in FIGS. 1 and 2, and the pressure chamber 21 and the exhaust hole 23 are blocked. Yes. In this embodiment, the state in which the tip tool 11 is pressed against the object and the O-ring 25 blocks the pressure chamber 21 and the exhaust hole 23 as shown in FIGS. 1 and 2 is referred to as a load state.

  On the other hand, in the state where the axis A1 intersects the vertical line and the striking force transmission member 18 is above the tip tool 11, there is no force to press the tip tool 11 against the object. When 11 moves under its own weight, the striking force transmission member 18 comes into contact with the tapered surface 17 by its own weight and stops, and the striker 19 also comes into contact with the striking force transmission member 18 with its own weight and stops. Therefore, the O-ring 25 attached to the striker 19 is positioned between the exhaust hole 23 and the tool holder 14 as shown in FIGS. 1 and 2, and the pressure chamber 21 and the exhaust hole 23 are connected. In the present embodiment, the state in which the force for pressing the tip tool 11 against the object is lost and the pressure chamber 21 and the exhaust hole 23 are connected as shown in FIGS. 3 and 4 is referred to as a no-load state.

  When the striking work machine 10 is in a load state, when the piston 20 operates from the top dead center to the bottom dead center and performs the striking work, the air in the pressure chamber 21 is exhausted from the breathing hole 22 and exhausted. It is not discharged from the hole 23. For this reason, the maximum pressure in the pressure chamber 21 is a pressure exceeding the threshold. On the other hand, when the striking work machine 10 is in an unloaded state, when the piston 20 operates from the top dead center toward the bottom dead center, the air in the pressure chamber 21 flows from the breathing hole 22 and the exhaust hole 23. Discharged. For this reason, the maximum pressure in the pressure chamber 21 is equal to or less than the threshold value.

  If the motor control unit 40 determines Yes in step S5, it proceeds to step S6 and maintains the set rotational speed of the brushless motor 35 at 2,700 rpm. On the other hand, if the motor control unit 40 determines No in step S5, it proceeds to step S7 and performs control to set the set rotational speed of the brushless motor 35 to 3,000 rpm.

  The motor control unit 40 executes step S6 or step S7, proceeds to step S8, and determines whether or not the trigger switch 71 is turned on. If the motor control unit 40 determines Yes in step S8, it returns to step S5. If it determines No in step S8, it proceeds to step S9 to stop the brushless motor 35 and ends the flowchart of FIG.

  FIG. 9 is an example of a time chart corresponding to the flowchart of FIG. In the time chart of FIG. 9, the horizontal axis indicates the rotation angle and time of the crankshaft 46, and the vertical axis indicates the pressure in the pressure chamber 21 and the rotation speed of the brushless motor 35. In the first cycle and the second cycle in which the crankshaft 46 continues, the pressure in the pressure chamber 21 is both equal to or less than the threshold value Pa1. For this reason, the set rotational speed of the brushless motor 35 is 2,700 rpm.

  Next, at time t1 during the third continuous cycle of the crankshaft 46 and at time t2 during the fourth cycle, a pressure exceeding the threshold value Pa1 is continuously detected. Then, at time t3 in the middle of the fourth cycle, the set rotational speed of the brushless motor 35 is changed from 2,700 rpm to 3,000 rpm. Further, after time t3, the pressure exceeding the threshold value Pa1 is detected between the fifth and sixth cycles, and the set rotational speed of the brushless motor 35 is maintained at 3,000 rpm. In the time chart of FIG. 9, for convenience, the change rate of the rotation angle is constant regardless of the rotation speed of the brushless motor 35.

  As described above, the motor control unit 40 executes the control example 1 and determines whether the striking work machine 10 is in the no-load state or the load state based on the detection result of the pressure in the pressure chamber 21. Then, the motor control unit 40 sets the rotation speed of the brushless motor 35 that is set when the striking work machine 10 is in a no-load state, that is, the rotation speed, when the striking work machine 10 is in a loaded state. The rotational speed of the brushless motor 35, that is, the rotational speed is made lower. Therefore, vibration and noise when the hitting work machine 10 is in a no-load state can be reduced, and power consumption can be reduced.

  Next, the control example 1 that determines the state of the impact working machine 10 from the pressure in the pressure chamber 21 and the comparative example that determines the state of the impact working machine from the value of the current flowing through the brushless motor will be compared. Then, the control example 1 has an advantage that the state of the hitting work machine 10 can be determined without being affected by the change in the voltage applied to the brushless motor 35.

  Note that the number of cycles used for the determination in step S5 may be three or more. Further, the determination content of step S5 may be “whether or not the maximum value of the pressure in the pressure chamber 21 detected within a predetermined time is equal to or less than a threshold value”. If the motor control unit 40 determines Yes in step S5 of this determination content, it proceeds to step S6, and if it determines No in step S5, it proceeds to step S7. Further, the set rotational speed of the brushless motor 35 is not limited to 2,700 rpm and 3,000 rpm, and the set rotational speed used in step S6 only needs to be lower than the set rotational speed used in step S7.

(Control example 2)
FIG. 10 is a flowchart for explaining the control example 2. The flowchart of FIG. 10 is started when the trigger switch 71 is turned on. In step S11, the motor control unit 40 rotates the brushless motor 35 at a set rotational speed corresponding to the operation of the rotational speed setting dial 53, for example, 3,000 rpm. In step S12, the motor control unit 40 detects the position of the crankshaft 46 at which the operating load of the piston 20 becomes the maximum value F-Max. Also in the control example 2, the rotational position of the crankshaft 46 is represented by a rotational angle θ with respect to the reference position G1.

  When the piston 20 moves in the cylinder 13 along the axis A1, the pressure in the pressure chamber 21 changes. The pressure in the pressure chamber 21 becomes a resistance when the piston 20 operates, that is, an operation load. The operation load of the piston 20 varies depending on the direction in which the piston 20 operates along the axis A1 and the position of the piston 20 in the direction along the axis A1. The operation load of the piston 20 is maximized immediately before hitting the striker 19 with the pressure of the pressure chamber 21 in the stroke in which the piston 20 moves from the top dead center toward the bottom dead center. In the present embodiment, the operating load of the piston 20 is normally the maximum value F-Max around the rotation angle of the crankshaft 46 of 90 degrees in the single working machine 10.

  However, the actual rotation angle of the crankshaft 46 at which the operating load of the piston 20 reaches the maximum value F-Max is not constant. For example, the actual rotation angle of the crankshaft 46 at which the operation load of the piston 20 reaches the maximum value F-Max varies depending on the working conditions such as the temperature of the environment in which the impact working machine 10 is used and the hardness of the object.

  In step S13, the motor control unit 40 determines whether or not the rotation angle of the crankshaft 46 at which the operating load of the piston 20 reaches the maximum value F-Max is 120 degrees or more for 10 consecutive cycles. The fact that the motor control unit 40 determines Yes in step S13 means that the follow-up operation of the striker 19 is faster than the normal follow-up speed with respect to the operation in which the piston 20 moves from the bottom dead center toward the top dead center. This means that there is a phenomenon that it is later than the normal follow-up start timing. For example, when the hardness of the object is lower than the reference hardness, the repulsive force at the time of impact is weaker than the reference value, and the above phenomenon occurs.

  Therefore, if the motor control unit 40 determines Yes in step S13, it proceeds to step S14, and performs a process of subtracting 500 rpm of the set rotational speed of the brushless motor 35 from the current set rotational speed. Next, in step S15, the motor control unit 40 determines "whether the set rotational speed after performing the subtraction process in step S14 is 1,500 rpm or less". If the motor control unit 40 determines No in step S15, the motor control unit 40 controls the brushless motor 35 at the set rotational speed after performing the subtraction process in step S14. In step S16, it is determined whether or not “5 seconds have elapsed since the start of control of the brushless motor 35 at the set rotational speed after performing the subtraction process in step S14”.

  If the motor control unit 40 determines No in step S16, it repeats the determination in step S16. If the motor control unit 40 determines Yes in step S16, it proceeds to step S17 and determines whether or not the trigger switch 71 is turned on. If the motor control unit 40 determines Yes in step S17, it returns to step S12, and if it determines No in step S17, it proceeds to step S18 to stop the brushless motor 35 and ends the flowchart of FIG.

  If the motor control unit 40 determines Yes in step S15, the motor control unit 40 proceeds to step S19 and executes “control for maintaining the set rotational speed before executing the subtraction process in step S14”. In step S20 following step S19, the motor control unit 40 determines whether or not the trigger switch 71 is turned on. If the motor control unit 40 determines Yes in step S20, it returns to step S19, and if it determines No in step S20, it proceeds to step S18.

  If the motor control unit 40 determines No in step S13, the motor control unit 40 proceeds to step S19 and performs "control to maintain the set rotational speed used before the determination in step S13".

  FIG. 11 is an example of a time chart corresponding to the flowchart of FIG. In the time chart of FIG. 11, the maximum value F-Max of the operating load of the piston 20 is replaced with the pressure in the pressure chamber 21. The set rotational speed before time t1 is 3,000 rpm. If the rotation angle of the crankshaft 46 at which the operating load of the piston 20 becomes equal to or greater than the maximum value F-Max before time t1 is 120 degrees or more continuously for 10 cycles or more, the set rotation speed from 3,000 rpm at time t1. Changed to 2,500 rpm. Thus, the rotational speed of the brushless motor 35 is lower than the rotational speed before the time t1 from the time t1 to the time t2, and the rotational speed after the time t2 is the rotational speed from the time t1 to the time t2. Lower than.

  Further, if the rotation angle of the crankshaft 46 at which the operating load of the piston 20 becomes equal to or greater than the maximum value F-Max after time t1 is 120 degrees or more continuously for 10 cycles or more, the set rotation speed at time t2 is It is changed from 2,500rpm to 2,000rpm. In the time chart of FIG. 11, for convenience, the change rate of the rotation angle of the crankshaft 46 is constant regardless of the rotation speed of the brushless motor 35.

  As described above, the control example 2 is used for controlling the brushless motor 35 when the operation in which the striker 19 follows the piston 20 is delayed from the normal follow-up speed or from the normal follow-up timing. Reduce the set speed. For this reason, the speed and follow-up timing at which the striker 19 follows the piston 20 can be brought close to the normal follow-up speed and normal follow-up timing. That is, the actual rotation angle θ of the crankshaft 46 at which the operation load of the piston 20 becomes the maximum value F-Max can be brought close to the rotation angle 90 degrees, and an efficient operation state can be achieved.

  Also, in step S16 of the flowchart of FIG. 10, the reason for determining “whether or not 5 seconds have elapsed since the start of control of the brushless motor 35 at the set rotational speed after the subtraction process of step S14” is determined. Even if “the brushless motor 35 is started to be controlled at the set rotational speed after the subtraction process in step S14”, the rotational angle θ of the crankshaft 46 at which the operating load of the piston 20 becomes the maximum value F-Max is Because it does not change immediately.

  Furthermore, in the flowchart of FIG. 10, when it is determined No in step S16, a new step for determining whether or not the trigger switch 71 is turned on is added. If the new step is Yes, the process proceeds to step S16. Returning, and if it is determined No in a new step, a routine that proceeds to step S18 may be adopted.

  In the control example 2, 3,000 rpm is exemplified as the set rotational speed used in step S11, but other rotational speeds may be used. Further, although 10 cycles are used for the determination in step S13, other numbers of cycles may be used. Furthermore, the rotation speed to be subtracted in step S14 may be a rotation speed other than 500 rpm.

(Control example 3)
FIG. 12 is a flowchart for explaining a control example 3 executed by the impact work machine 10. First, when the trigger switch 71 is turned on, the motor control unit 40 starts the flowchart of FIG. 12, and in step S21, current is supplied to the coils U1, V1, and W1 to rotate the brushless motor 35. If the tip tool 11 is pressed against the object and the striker 19 is stopped at the second predetermined position or moved at the first predetermined position at the time of control in step S21, the piston 20 is reciprocated. The striker 19 strikes the striking force transmission member 18 by the operation, and the striking force is transmitted to the tip tool 11. Here, the second predetermined position is a range of the striker 19 in the direction of the axis A <b> 1 in which the O-ring 25 opens the exhaust hole 23.

  In step S22, the motor control unit 40 determines whether or not the striker sensor 80 has detected that the striker 19 is in the first predetermined position. The determination in step S <b> 22 is performed to determine whether or not the hitting work machine 10 is in a no-load state from the position of the hitting element 19. Here, “the striker 19 is in the first predetermined position” means “the striker 19 is located at a position where the pressure chamber 21 and the exhaust hole 23 are connected” as shown in FIGS. 3 and 4. Means. That is, when the striker 19 is in the first predetermined position, the O-ring 25 is positioned between the exhaust hole 23 and the tool holder 14 in the direction along the axis A1. Note that “the striker 19 is at the first predetermined position” does not mean “the striker 19 is stopped at the first predetermined position”.

  The fact that the motor control unit 40 determines Yes in step S22 means that after the motor control unit 40 performs the striking work by executing the control in step S21, the operator presses the tip tool 11 against the object. The power is once released. That is, the impact work machine 10 is in an unloaded state.

  Therefore, if the motor control unit 40 determines Yes in step S22, the process proceeds to step S23, and during the operation of the crankshaft 46 for 50 consecutive cycles, the pressure in the pressure chamber 21 exceeds the second threshold value for 50 cycles. It is determined whether or not all of the above are detected. The second threshold value used for the determination in step S23 is a state in which the piston 20 is reciprocated and the blanking is performed with the operator separating the tip tool 11 from the object. It is a value for judging indirectly from pressure. The second threshold value is stored in the memory of the controller 64. Comparing the second threshold value with the first threshold value used in step S5 in FIG. 8, the first threshold value is preferably larger than the second threshold value.

  If the motor control unit 40 determines Yes in step S23, it proceeds to step S24, and "After determining Yes in step S23, the striker 19 is moved to the first predetermined position within two cycles by the operation of the crankshaft 46." It is determined whether or not it has been detected. The fact that the motor control unit 40 determines Yes in step S24 means that the situation where the batting work machine 10 is performing idle driving has been continued for a predetermined time. The idle driving means that the piston 20 reciprocates while the striking force transmission member 18 is in contact with the tapered surface 17 and the striking element 19 strikes the striking force transmission member 18. As described above, even if the striker 19 is in the first predetermined position, if the piston 20 operates, the strike force is generated, and the striker 19 strikes the strike force transmission member 18 and the impact force is generated by the impact force. 19 moves in a direction approaching the piston 20, and an idling phenomenon occurs.

  Therefore, if the motor control unit 40 determines Yes in step S24, it proceeds to step S25 to stop the brushless motor 35 and ends the flowchart of FIG. When the blow working machine 10 performs the blank shot, the blow force applied to the blow force transmission member 18 is transmitted to the cylinder housing 12 via the tool holder 14. On the other hand, in the present embodiment, when the blow work machine 10 is idle, the brushless motor 35 is stopped, so that the blow work can be avoided and the life of the blow work machine 10 can be extended.

  On the other hand, if the motor control unit 40 determines No in step S24, it proceeds to step S26 and determines whether or not the trigger switch 71 is turned on. If the motor control unit 40 determines Yes in step S26, it returns to step S22. That is, the brushless motor 35 is maintained in a rotated state. On the other hand, if the motor control unit 40 determines No in step S26, the process proceeds to step S25. Further, when it is determined No in step S22, the process proceeds to step S26.

  If the motor control unit 40 determines No in step S23, it proceeds to step S26. In other words, even if the hammering machine 10 is idle, the trigger switch 71 is turned on if the time during which the tip tool 11 is separated from the object is short and is less than 50 cycles in terms of the crankshaft 46 cycle. As long as it is turned on, the brushless motor 35 is not stopped. For this reason, even when the operator temporarily removes the tip tool 11 from the object, if the trigger switch 71 is turned on, the brushless motor 35 is not stopped, and the tip tool 11 is pressed against the object next time. In this case, it is not necessary to restart the brushless motor 35, and it is possible to suppress a decrease in the work efficiency. In particular, if the hitting work machine 10 is a product provided with an on-lock mechanism that locks the trigger switch 71 in the on state, there is a great advantage.

  As described above, the control example 3 is the second threshold value of the pressure in the pressure chamber 21 while the striker 19 is detected at the first predetermined position and the crankshaft 46 continuously operates for 50 cycles. Then, the brushless motor 35 is stopped. For this reason, the control example 3 is temporarily subject to the tip tool 11 while performing the striking work, compared to the control for preventing the striking work machine 10 from being idle based only on the detection result of the position of the striking element 19. When the tip tool 11 is pressed against the target object next time, the brushless motor 35 can be prevented from being stopped each time the tip tool 11 is moved away from the target object, and the hitting workability is improved. To do.

  In step S23 or step S24, the elapsed time may be measured instead of using the number of operation cycles of the crankshaft 46. For example, if the elapsed time is equal to or longer than the predetermined time, it is determined as Yes in step S23 or step S24, and if the elapsed time is less than the predetermined time, it is determined as No in step S23 or step S24. Note that the predetermined time used for the determination in step S23 is longer than the predetermined time used for the determination in step S24.

(Control example 4)
A control example 4 that can be executed by the impact work machine 10 will be described. When the trigger switch 71 is turned on, the motor control unit 40 controls the rotation speed of the brushless motor 35 based on the set rotation speed set by the rotation speed setting dial 53. Further, the motor control unit 40 detects the position of the piston 20 at which the operating load becomes the maximum value F-Max, similarly to the process of step S12 of FIG. The position of the piston 20 can be estimated from the signal of the crank position detection sensor 72.

  Next, after the motor control unit 40 detects the position of the piston 20 at which the operating load reaches the maximum value F-Max, in the operation cycle of the piston 20, the position of the piston 20 indicates that the operating load is at the maximum value F-Max. Before reaching the position, the control is performed to make the rotation speed of the brushless motor 35 higher than the set rotation speed. Furthermore, when the position of the piston 20 passes the position where the operating load reaches the maximum value F-Max, the motor control unit 40 reduces the rotational speed of the brushless motor 35 and returns it to the set rotational speed.

  As described above, the brushless motor 35 has the rotational speed of the brushless motor 35 when the piston 20 operates in the first range including the position where the pressure in the pressure chamber 21 is maximum, and the second range other than the first range is the piston. Control is performed so that the rotational speed of the brushless motor 35 is higher than that when the motor 20 operates. Therefore, it is possible to suppress the impact force from being reduced due to a decrease in the operating speed of the piston 20.

  The correspondence between the configuration of the present embodiment and the configuration of the present invention will be described. The pressure chamber 21 corresponds to the pressure chamber of the present invention, and the tip tool 11 corresponds to the tip tool of the present invention. Moreover, the cylinder 13, the striking force transmission member 18, the striking element 19, the piston 20, the pressure chamber 21, the power conversion mechanism 45, and the brushless motor 35 are included in the striking mechanism 83 of the present invention. The crankshaft 46 and the connecting rod 47 correspond to the power conversion mechanism of the present invention. The pressure sensor 73 corresponds to the pressure detection unit of the present invention, the controller 64 corresponds to the first determination unit of the present invention, and the motor control unit 40 corresponds to the control execution unit of the present invention. The current value and applied voltage of the current supplied to the coils u1, V1, and W1, the rotation speed and rotation speed of the brushless motor 35 are included in the output of the motor of the present invention. The reference position G1 in FIG. 5 corresponds to the reference position of the present invention, 90 degrees described with reference to FIG. 5 corresponds to the reference angle of the present invention, and the threshold used in step S5 in FIG. The threshold value used in step S23 of FIG. 12 corresponds to the second predetermined value of the present invention. The crank position detection sensor 72 corresponds to the angle detection unit of the present invention, the striker sensor 80 and the controller 64 correspond to the second determination unit of the present invention, and the output unit 81 corresponds to the output unit of the present invention. .

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the impact working machine of the present invention includes an impact working machine in which a battery pack as a DC power source is attached to a housing and the electric power of the battery pack is supplied to a brushless motor.

  The striking work machine of the present invention includes a hammer driver or a hammer drill capable of applying a striking force and a rotational force in the axial direction to the tip tool, in addition to a hammer that imparts a striking force in the axial direction to the tip tool. The electric motor used in the striking work machine of the present invention may be a brushed motor in addition to a brushless motor. The brushed motor may not be provided with a magnetic sensor for detecting the rotational position of the rotor. In this case, the motor control unit detects the position of the operating member from the crank position detection signal. The motor of the present invention includes an engine, a hydraulic motor, and a pneumatic motor in addition to the electric motor. The pressure sensor of the present invention can be attached to a location where the pressure of the pressure chamber acts on the cylinder and does not contact the piston and the striker. The power conversion mechanism of the present invention includes a structure having a cam mechanism in addition to a structure having a crankshaft and a connecting rod.

  Further, in the striking work machine, a cylindrical piston may be disposed in a cylinder so as to be able to reciprocate, and a striking element may be disposed in the piston. The piston corresponds to the operating member of the present invention. Further, the end of the piston in the axial direction is closed by a lid, and a pressure chamber is provided between the lid and the striker. In the hitting work machine having this configuration, the axis on which the operating member operates and the axis of the output shaft of the motor are arranged coaxially or in parallel.

  DESCRIPTION OF SYMBOLS 10 ... Blow working machine, 11 ... Tip tool, 13 ... Cylinder, 18 ... Blowing force transmission member, 19 ... Strike element, 20 ... Piston, 21 ... Pressure chamber, 35 ... Brushless motor, 40 ... Motor control unit, 45 ... Power Conversion mechanism 46 ... crankshaft 47 ... connecting rod 64 ... controller 72 ... crank position detection sensor 73 ... pressure sensor 80 ... striker sensor 81 ... output unit 83 ... striking mechanism

Claims (10)

A striking work machine equipped with a striking mechanism for striking a tip tool using the pressure in the pressure chamber,
A pressure detector for detecting the pressure in the pressure chamber;
A first determination unit for determining a state of the striking mechanism based on the detection result of the pressure;
A control execution unit that executes control based on a determination result of the first determination unit;
Having a striking work machine. The striking mechanism is
An impactor that reciprocates due to a pressure change in the pressure chamber and that strikes the tip tool;
A piston provided between the striking element and the pressure chamber, and provided so as to be capable of reciprocating;
A motor that generates rotational force;
A power conversion mechanism that converts the rotational force of the motor into the reciprocating force of the piston;
The striking work machine according to claim 1, comprising:   The striking work machine according to claim 2, wherein the control executed by the control execution unit is control of an output of the motor. The state of the striking mechanism determined by the first determining unit is whether or not the follower movement of the striking element with respect to the operation of the piston is slower than normal.
The control execution unit lowers the rotational speed of the motor when the follower movement of the striker is slower than normal, lower than the rotational speed of the motor when the follower movement of the striker is normal. 3. The hitting work machine according to 3. The state of the impact mechanism determined by the first determination unit is whether or not the pressure is a first predetermined value or less,
The said control execution part makes the rotation speed of the said motor in case the said pressure is below 1st predetermined value lower than the rotation speed of the said motor in case the said pressure exceeds 1st predetermined value. 3. The hitting work machine according to 3. The state of the impact mechanism determined by the first determination unit is the position of the piston when the pressure in the pressure chamber is maximum,
The control execution unit controls the rotation speed of the motor when the piston operates in a first range including a position where the pressure in the pressure chamber becomes maximum, and the piston operates in a second range other than the first range. The striking work machine according to claim 2, wherein the hammering speed is higher than the rotational speed of the motor in the case of performing. The power conversion mechanism has a crankshaft that rotates when the rotational force of the motor is transmitted and converts the rotational force into a reciprocating force of the piston,
An angle detector for detecting a rotation angle of the crankshaft relative to a reference position of the crankshaft is provided;
The state of the striking mechanism determined by the first determination unit is whether or not a rotation angle of the crankshaft when the pressure in the pressure chamber becomes maximum is larger than a predetermined reference angle,
The control execution unit is configured such that the rotation speed of the motor when the rotation angle of the crankshaft is larger than the reference angle is greater than the rotation speed of the motor when the rotation angle of the crankshaft is equal to or less than the reference angle. The hitting work machine according to claim 3, wherein the hitting work machine is lowered. A second determination unit for determining whether or not the tip tool is pressed against the object;
The striking work machine according to claim 5, wherein the control execution unit stops the motor when the tip tool is not pressed against an object and the pressure in the pressure chamber is equal to or lower than a second predetermined value. . An output unit is provided to notify the operator of the state of the striking mechanism,
The control executed by the control execution unit is control that causes the output unit to notify the state of the hitting mechanism determined by the first determination unit. Blow work machine.   The striking work machine according to any one of claims 2 to 8, wherein the pressure detection unit is a pressure sensor provided in the piston.

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