Work machine

Abstract

To improve the convenience of a work machine.SOLUTION: A work machine 10 includes: an electric motor 58; a battery pack 28 for supplying electric power to the electric motor 58; and an inverter circuit 144 disposed between the battery pack 28 and the electric motor 58 in a power path 142 for supplying power from the battery pack 28 to the electric motor 58, and controlling power to be supplied to the electric motor 58. The work machine 10 further includes: a control section 130 which controls driving of the electric motor 58 by controlling the inverter circuit 144; and a fuse 141 disposed in the power path 142 and capable of blocking the power path 142 by being cut. The control section 130 cuts the fuse 141 by supplying power to the electric motor 58 from the inverter circuit 144 so that the electric motor 58 does not rotate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] Patent Document 1 describes a work machine equipped with a drum-type magazine that stores a plurality of fasteners in a roll form. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-157401 Summary of the Invention [Problem to be solved by the invention]

[0004] The work machine (driving machine) described in Patent Document 1 is equipped with a supply mechanism that feeds fasteners stored in a magazine toward an ejection unit, and the supply mechanism has a built-in solenoid. A solenoid drive switch is provided in the control circuit that drives the solenoid.

[0005] However, if the solenoid drive switch shorts out, there is no means to stop the power supply to the solenoid, so power continues to be supplied to the solenoid, resulting in over-discharge of the battery, which increases the frequency of battery charging and shortens the battery life, reducing the usability of the work machine.

[0006] An object of the present invention is to provide a work machine with improved convenience. [Means for solving the problem]

[0007] In one embodiment, the work machine comprises a motor, a power supply unit that supplies power to the motor, a drive circuit that is interposed between the power supply unit and the motor in a power path that supplies power from the power supply unit to the motor and controls the power supplied to the motor, a control unit that controls the drive of the motor by controlling the drive circuit, and a fuse that is interposed between the power supply unit and the drive circuit in the power path and can interrupt the power path by being cut off, and the control unit cuts off the fuse by supplying power from the drive circuit to the motor so that the motor does not rotate.

[0008] In another embodiment, the work machine includes a motor, a power supply unit that supplies power to the motor, a control unit that controls the driving of the motor, an auxiliary drive unit that branches off between the power supply unit and the motor in a power path that supplies power from the power supply unit to the motor and is connected to the power supply unit in parallel with the motor, a fuse that is interposed in the power path between the power supply unit and the motor and the auxiliary drive unit and that can cut off the power path by cutting the fuse, an ejection unit to which fasteners are supplied, a striking unit that operates by receiving driving force from the motor and strikes the fasteners supplied to the ejection unit, a magazine unit that stores a plurality of the fasteners wound in a roll, and a supply unit that operates by receiving driving force from the auxiliary drive unit and supplies the fasteners from the magazine unit to the ejection unit, and the control unit cuts off the fuse when an abnormality occurs in the auxiliary drive unit. [Effects of the Invention]

[0009] According to the present invention, the convenience of the work machine can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing the appearance of a work machine according to an embodiment of the present invention. [Figure 2] 2 is a circuit block diagram showing the circuit configuration of the work machine of FIG. 1. [Figure 3] 2 is a plan view showing a mechanism for supplying fasteners to an ejection unit in the work machine of FIG. 1. FIG. [Figure 4] 2 is a current supply pattern diagram showing an example of a current supply pattern during normal operation in the drive circuit of the work machine of FIG. 1. FIG. [Figure 5] 2 is a current flow pattern diagram showing an example of a current flow pattern when a fuse in a drive circuit of the work machine in FIG. 1 is cut off. FIG. [Figure 6] 2 is a timing chart showing an example of a solenoid current during normal operation of the work machine of FIG. 1. [Figure 7] 2 is a timing chart showing an example of the overall current and motor drive duty during normal operation of the work machine of FIG. 1; [Figure 8] 2 is a timing chart showing an example of a motor current and a motor drive duty during normal operation of the work machine of FIG. 1. [Figure 9] 3 is a flowchart for detecting a failure in a solenoid drive switch of the work machine of FIG. 1. [Figure 10] 2 is a flowchart of current control after a failure is detected in a solenoid drive switch of the work machine of FIG. 1. [Figure 11] 4 is a timing chart showing an example of a solenoid current when a fuse of the work machine of FIG. 1 is blown. [Figure 12] 4 is a timing chart showing an example of a motor current when a fuse of the work machine of FIG. 1 is blown. [Figure 13] 4 is a timing chart showing an example of the total current and motor drive duty when a fuse of the work machine of FIG. 1 is blown. DETAILED DESCRIPTION OF THE INVENTION

[0011] The working machine of this embodiment will be described with reference to the drawings.

[0012] The working machine 10 of this embodiment is, for example, an electric nail gun. In the working machine 10, when a predetermined condition is satisfied, a nail N (see FIG. 3), which is an example of a fastener, is struck by a striking unit 48, which will be described later. In this case, the nail N is ejected from an ejection unit 42, which will be described later, and driven into a target material G.

[0013] In the following description, the direction in which the striking portion 48 strikes the nail N is referred to as the up-down direction. The striking portion 48 strikes the nail N downward in the up-down direction. Directions perpendicular to the up-down direction are referred to as the front-rear direction and the left-right direction. The front-rear direction and the left-right direction are perpendicular to each other.

[0014] <Overall structure> As shown in Figures 1 to 3, the work machine 10 has a housing 12, an impact biasing unit 32, an ejection unit 42, an impact unit 48, a drive unit 56, a lifting unit 66, a magazine unit 74, a supply unit 70, and a control unit 130.

[0015] <Housing 12> The housing 12 is an outer shell element of the work implement 10. The housing 12 is made up of two housing members that are butted against each other in the left-right direction and fixed with screws (not shown). As a result, the various components of the work implement 10 are housed inside the housing 12.

[0016] The housing 12 has a cylinder case 13, a motor case 14, a handle 15, and an attachment portion 16. The cylinder case 13 is cylindrical and extends in the vertical direction. A striking portion 48 is housed inside the cylinder case 13. The motor case 14 extends rearward from the lower portion of the cylinder case 13 in the front-to-rear direction. The motor case 14 houses an electric motor 58 and a gear case 62 of a drive portion 56, which will be described later.

[0017] The handle 15 extends rearward from the center of the cylinder case 13 in the front-to-rear direction. The handle 15 is the part of the housing 12 that the operator grasps. The handle 15 is provided with a trigger 19. The trigger 19 is an operating part that is operated by the operator when driving in the nail N. When the operator operates the trigger 19, an ON signal or OFF signal is sent from the trigger switch 191 to the control unit 130.

[0018] The mounting portion 16 straddles the rear end of the motor case 14 and the rear end of the handle 15. A battery pack 28 is detachably attached to the mounting portion 16. A control unit 130 is also housed inside the mounting portion 16.

[0019] <Impact biasing section 32> The impact biasing portion 32 biases the impact portion 48 downward (toward the injection portion 42), which is one side in the up-down direction (i.e., the first direction). The impact biasing portion 32 is composed of a cylinder 36, a piston chamber 37, a pressure accumulator container 38, etc. A pressure accumulator chamber 38a is formed inside the pressure accumulator container 38. The impact biasing portion 32 biases the impact portion 48 downward by the pressure of the compressed air in the pressure accumulator chamber 38a.

[0020] The cylinder 36 is provided inside the cylinder case 13. The pressure accumulator container 38 is provided in an upper part inside the cylinder case 13. A pressure accumulator chamber 38a formed by the pressure accumulator container 38 is in communication with the piston chamber 37. The piston chamber 37 and the pressure accumulator chamber 38a are filled with compressed air, as an example of high-pressure gas. A damper 39 is provided below the cylinder 36. When the pressure in the pressure accumulator chamber 38a drops, the pressure in the pressure accumulator chamber 38a can be increased to a predetermined pressure by sending air into the pressure accumulator chamber 38a.

[0021] The damper 39 is a member made of, for example, rubber or urethane. When a piston 52 of the striking unit 48 (described later) reaches the bottom dead center, the damper 39 comes into contact with the piston 52. This prevents the piston 52 from colliding with the cylinder 36.

[0022] <Injection part 42> The ejection section 42 is located below the cylinder case 13. The ejection section 42 extends downward from the lower end of the cylinder 36 in the vertical direction. An ejection port 46 is provided inside the ejection section 42. An ejection end 47 is provided at the lower end of the ejection port 46. Nails N are supplied one by one from the magazine section 74 to the ejection port 46 by the supply section 70, which will be described later, and are supported within the ejection port 46. In other words, the nails N, which are fasteners, are supplied to the ejection section 42.

[0023] The ejection unit 42 is provided with a push lever 44. The push lever 44 is held by the ejection unit 42 so as to be movable in the up and down direction. The push lever 44 is also biased downward by a spring (not shown). When the push lever 44 is pressed against the target material G, it moves upward against the biasing force of the spring.

[0024] <Striking section 48> The striking section 48 strikes the nail N, which has been supplied to and supported by the ejection section 42, towards a mating material G. The striking section 48 has a piston 52 and a driver blade 54.

[0025] The piston 52 is accommodated in the cylinder 36 so as to be able to reciprocate vertically. That is, the piston 52 is provided in the cylinder 36 so as to be able to reciprocate between top dead center and bottom dead center along the axial direction of the cylinder 36. The piston 52 is also urged downward in the vertical direction by the pressure of the compressed air in the accumulator chamber 38a. The piston 52 defines the interior of the cylinder 36, thereby defining a piston chamber 37. Therefore, the volume of the piston chamber 37 increases and decreases as the piston 52 reciprocates. A seal member (not shown) is provided on the outer peripheral surface of the piston 52. A driver blade 54 is connected to the underside of the piston 52.

[0026] The driver blade 54 is, for example, a plate-shaped member made of metal. The driver blade 54 extends downward in the vertical direction from the underside of the piston 52. The driver blade 54 is capable of vertically reciprocating within the cylinder 36 together with the piston 52. This vertical reciprocating motion causes the driver blade 54 to pass vertically through the injection port 46. The driver blade 54 moves downward within the injection port 46 and strikes the heads of the nails N sequentially fed into the injection port 46 downward.

[0027] A plurality of racks (not shown) are disposed in the center of the driver blade 54. The driver blade 54 moves upward in the vertical direction by the driving force of an electric motor 58 (described later) via a lifting portion 66 (described later) that engages with the racks. Note that the downward movement of the driver blade 54 in the vertical direction is referred to as "downward." The upward movement of the driver blade 54 in the vertical direction is referred to as "upward."

[0028] <Driver 56> 1 drives the striking unit 48. The striking unit 56 has an electric motor (motor) 58 and a gear case 62. The operation of the striking unit 56 is controlled by a control unit 130, which will be described later. The striking unit 48 is operated by receiving power from the battery pack 28, and is capable of moving the striking unit 48 upward against the biasing force of the striking biasing unit 32.

[0029] The electric motor 58 is housed in the motor case 14. The electric motor 58 is, for example, a brushless motor having a rotor 58b and a stator. The electric motor 58 receives a supply of electric power from the battery pack 28 and rotates.

[0030] The gear case 62 is provided in front of the electric motor 58 inside the motor case 14. A reduction mechanism having an input element, an output element, and multiple sets of planetary gear mechanisms is provided inside the gear case 62. The input element of the reduction mechanism is connected to the rotating shaft of the electric motor 58, and the input element is rotatably supported by a bearing. The rotational force of the output element of the reduction mechanism inside the gear case 62 is transmitted to the lifting part 66.

[0031] The lifting unit 66 rotates by receiving a driving force from the electric motor 58, converts the rotational force of the electric motor 58 into a moving force in the vertical direction, and transmits it to the driver blade 54. The lifting unit 66 has a pinwheel and a pinion pin (not shown). The pinwheel is rotatable around the same central axis as the rotational shaft of the electric motor 58.

[0032] A plurality of pinion pins are provided on the pinwheel. The pinion pins are provided at intervals within a predetermined angular range in the rotational direction of the pinwheel. The pinion pins can be engaged and disengaged with the rack on a one-to-one basis. When at least one pinion pin is engaged with the rack, the rotational force of the pinwheel is transmitted to the driver blade 54. When all pinion pins are disengaged from the rack, the rotational force of the pinwheel is not transmitted to the driver blade 54.

[0033] <Battery Pack 28> As shown in FIG. 1, the battery pack (power supply unit) 28 is detachably attached to the mounting portion 16 and is a DC power supply that supplies power to the electric motor 58 and other components. The battery pack 28 has a housing case and a plurality of battery cells housed within the housing case. The battery cells are secondary batteries that can be charged and discharged, and can be any of lithium-ion batteries, nickel-metal hydride batteries, lithium-ion polymer batteries, and nickel-cadmium batteries. As shown in FIG. 2, the battery pack 28 incorporates a controller 28a, a cell voltage detection circuit 28b, and a cell current detection circuit 28c, and the cell voltage values ​​detected by the cell voltage detection circuit 28b and the cell current values ​​detected by the cell current detection circuit 28c are output to the controller 28a.

[0034] <Control unit 130> The control unit 130 is, for example, a microcomputer having an input port, an output port, an arithmetic processing unit, and a storage unit. The control unit 130 is electrically connected to the trigger switch 191, the push switch 162, etc. by wiring. The control unit 130 controls the driving of the electric motor 58 in response to the operation of the trigger 19 and the pushing operation of the push lever 44 by the operator.

[0035] <Magazine Section 74> Fig. 3 is a top view of a portion of the magazine unit 74 and the supply unit 70, which will be described later. The magazine unit 74 shown in Fig. 1 is attached to the lower part of the housing 12. In other words, the magazine unit 74 is supported by the housing 12. As shown in Figs. 1 and 3, the magazine unit 74 has a hollow drum unit 75, a guide unit 76, and a lid unit 78. A plurality of nails N are stored inside the drum unit 75 in a rolled state. The plurality of nails N are connected by a connecting unit M such as a wire.

[0036] The guide portion 76 extends forward from the drum portion 75 and is connected to the ejection portion 42. Specifically, the guide portion 76 extends along the K1 direction, which intersects with the left-right and up-down directions. Some of the multiple nails N are supported in the guide portion 76 with their axial direction perpendicular to the K1 direction, and are lined up along the K1 direction. The multiple nails N are moved along the K1 direction and supplied to the ejection portion 42. In the following description, the K1 direction will also be referred to as the supply direction K1.

[0037] The lid portion 78 is provided opposite the guide portion 76 in the left-right direction. A supply path 82 is provided between the lid portion 78 and the guide portion 76. The supply path 82 extends in the supply direction K1 toward the injection port 46. The multiple nails N wound in a roll in the drum portion 75 are aligned in a line in the supply direction K1 by the supply path 82 and fed one by one into the injection port 46. In other words, the supply path 82 is a passage provided in the magazine portion 74 that lines up the multiple nails N, which are fasteners, and supplies them to the injection portion 42.

[0038] The lid portion 78 is provided so as to be rotatable in the R1 direction around a rotation shaft 84. The rotation shaft 84 is provided in the injection portion 42 and extends in the vertical direction. The supply path 82 can be opened and closed by rotating the lid portion 78, and an operator can set nails N inside the drum portion 75 or remove the nails N from inside the drum portion 75 by opening the supply path 82. In other words, the lid portion 78 is opened and closed when inserting or removing the nails N into or from the magazine portion 74. The lid portion 78 is provided with a claw member 86 and a spring 88.

[0039] The claw member 86 has a base 86a, a plate 86b, and a claw 86c. The base 86a rotates around a rotation shaft 89 that extends in the vertical direction. The plate 86b extends forward from the base 86a. The plate 86b is biased toward the supply path 82 by a spring 88. The claw 86c is a protrusion that protrudes from the plate 86b toward the supply path 82.

[0040] <Supply section 70> The supply unit 70 includes a feeder 92 , a supply biasing unit 126 , and a supply driving unit 120 .

[0041] The feeder 92 is a feeding member that moves toward the ejection section 42 along the feeding direction K1, thereby feeding the nails N stored in the magazine section 74 to the ejection section 42. The feeder 92 performs linear motion along the feeding direction K1.

[0042] The feeder 92 has a movable member 94, a feeding member 96, and a spring 98. The movable member 94 has a fixed portion 94a and a shaft portion 94c. The fixed portion 94a is fixed to a plunger 124 of the supply drive unit 120. The fixed portion 94a is capable of reciprocating in the supply direction K1 in accordance with the movement of the plunger 124. The shaft portion 94c is a rod-shaped member extending in a direction perpendicular to the supply direction K1.

[0043] The feed member 96 is provided rotatably around the shaft 94c. The feed member 96 has a first claw 96a and a second claw 96b. The first claw 96a and the second claw 96b protrude into the supply path 82. The first claw 96a feeds the leading nail N to the ejection unit 42. The second claw 96b feeds the second nail N toward the ejection unit 42.

[0044] The spring 98 is a torsion spring that is wound around the shaft portion 94c and biases the feeding member 96 toward the supply path 82.

[0045] <Supply drive unit 120> The supply drive unit 120 is fixed to the right side of the guide unit 76. The supply drive unit 120 is controlled by the control unit 130 to control the movement of the feeder 92 along the supply direction K1. That is, the supply drive unit 120 is controlled by the control unit 130 to move and regulate the movement of the feeder 92 along the supply direction K1.

[0046] The supply drive unit 120 has a solenoid 122, a plunger 124, and a supply biasing unit 126. The solenoid 122 has a bobbin, a coil provided inside the bobbin, and the like. The plunger 124 is fixed (connected) to the feeder 92. When energized, the solenoid 122 can move the feeder 92 in the supply direction K1 toward the side opposite the injection unit 42. In other words, the supply drive unit 120 can drive the feeder 92 so as to bias it toward the side opposite the injection unit 42.

[0047] The supply biasing portion 126 is a biasing member such as a coil spring. The plunger 124 is inserted into the supply biasing portion 126. The supply biasing portion 126 is disposed between the solenoid 122 and the movable member 94, and biases the feeder 92 toward the injection portion 42 along the supply direction K1.

[0048] When the power supply to the solenoid 122 is turned off, the feeder 92 is urged toward the ejection unit 42 in the supply direction K1 by the urging force of the supply urging unit 126. In other words, when the power supply to the solenoid 122 is turned off, the plunger 124 moves toward the ejection unit 42 in the supply direction K1 by the urging force of the supply urging unit 126. When the plunger 124 moves toward the ejection unit 42, the feeder 92 fixed to the plunger 124 moves toward the ejection unit 42 in the supply direction K1, and the nail N is fed to the ejection port 46.

[0049] Thereafter, when power is supplied to the solenoid 122, the coil of the powered solenoid 122 generates a magnetic attractive force. This magnetic attractive force causes the plunger 124 to move in the opposite direction from the injection unit 42 in the supply direction K1 against the biasing force of the supply biasing unit 126. As a result, the feeder 92 fixed to the plunger 124 moves in the opposite direction from the injection unit 42 in the supply direction K1.

[0050] The supply unit 70 has the above configuration and performs the above operation by power supply according to the control of the control unit 130, thereby supplying the nails N in the magazine unit 74 to the ejection port 46. In other words, the supply unit 70 is operated by the control unit 130 and supplies the nails N, which are fasteners, from the magazine unit 74 to the ejection unit 42.

[0051] <Driving operation of the work machine> When the operator operates the trigger 19 and the push lever 44, turning on the trigger switch 191 and the push switch 162, the control unit 130 controls the electric motor 58 of the drive unit 56 to be supplied with power from the battery pack 28. When the electric motor 58 receives the power and starts to rotate, the driving force is transmitted to the driver blade 54 of the striking unit 48 via the lifting unit 66. Then, the driver blade 54 (i.e., the striking unit 48) is lifted by the lifting unit 66 from the standby position to the top dead center against the biasing force of the striking biasing unit 32. In other words, the driver blade 54 rises.

[0052] When the rack of the driver blade 54 and the pinion pin of the lifting portion 66 are disengaged, the striking portion 48 moves downward due to the biasing force of the striking biasing portion 32. That is, the striking portion 48 moves from the top dead center to the bottom dead center.

[0053] The driver blade 54 rises from the standby position toward the top dead center, is released at the top dead center, and then descends toward the bottom dead center, whereby the nail N is struck by the driver blade 54 and driven into the mating material G. In other words, the head of the nail N located inside the injection port 46 is struck by the driver blade 54, and as a result, the nail N is driven into the mating material G.

[0054] After the driving operation, the striking unit 48 moves upward against the biasing force of the striking biasing unit 32 due to re-engagement of the rack of the driver blade 54 with the pinion pin of the lifting unit 66. The striking unit 48 is then moved by the lifting unit 66 from the bottom dead center to the standby position, where it stops. The next nail N is then supplied to the ejection port 46 and supported.

[0055] <Control system of work machine 10> The control system of the work implement 10 will be described with reference to Figure 2. Note that a description of the configuration already described will be omitted. In the work implement 10, power is supplied from the battery pack (power supply unit) 28 to the electric motor 58 via the mounting unit 16. Specifically, the battery pack 28 and an inverter circuit (drive circuit) 144 are connected by a main body circuit unit 143 including a power path 142, and the electric motor 58 is further connected to the inverter circuit 144. In other words, the inverter circuit 144 is interposed between the battery pack 28 and the electric motor 58 in the power path 142 that supplies power from the battery pack 28 to the electric motor 58, and is a drive circuit that controls the power supplied to the electric motor 58.

[0056] Therefore, the control unit 130 controls the inverter circuit 144 to control the driving of the electric motor 58. The electric motor 58 is, for example, a three-phase brushless motor having a U-phase, a V-phase, and a W-phase.

[0057] In the main circuit section 143, the inverter circuit 144 converts the power supplied from the battery pack 28 into drive power and supplies it to the electric motor 58. The inverter circuit 144 is provided with six switching elements 144a, 144b, 144c, 144d, 144e, and 144f. The switching elements 144a, 144b, 144c, 144d, 144e, and 144f are, for example, field effect transistors (FETs). Therefore, the electric motor 58 is driven by switching three phases of the electric motor 58 ON / OFF using the six FET switches.

[0058] The control signal output circuit 147 operates the inverter circuit 144 based on instructions from the control unit 130. Therefore, based on instructions from the control unit 130, the six switching elements 144a, 144b, 144c, 144d, 144e, and 144f are switched ON and OFF to rotate the electric motor 58. The electric motor 58 is then driven to rotate by the power supplied via the inverter circuit 144, thereby driving the striking unit 48. Three magnetic sensors H1 detect the rotation state of the rotor 58b of the electric motor 58.

[0059] The rotor position detection circuit 132 detects the rotational position of the pinwheel 68 of the lifting part 66 based on information about the rotation state of the rotor 58b obtained from the three magnetic sensors H1. The rotor position information obtained by the rotor position detection circuit 132 is output to the control part 130.

[0060] A branch circuit 146 branching off from the power path 142 of the main circuit unit 143 is provided with a solenoid 122 and a solenoid drive switch 153 that switches the operation of the solenoid 122. The solenoid drive switch 153 is a switching element, such as a FET. The control unit 130 controls the solenoid drive switch 153 to switch between ON and OFF. This switches the state of current flow to the solenoid 122, and drives the feeder 92.

[0061] A battery voltage detection circuit 154 detects a voltage corresponding to the residual power of the battery pack 28 when power is supplied to the electric motor 58 via the inverter circuit 144. A motor current detection circuit (motor current detection unit) 155 detects the value of a current flowing through the electric motor 58. A solenoid current detection circuit (auxiliary drive unit current detection unit) 156 detects a current flowing through the solenoid 122 (auxiliary drive unit 157).

[0062] Furthermore, a fuse 141 is interposed between the battery pack 28 and the inverter circuit 144 in the power path 142 of the main circuit unit 143. The fuse 141 can cut off (melt) itself to interrupt the power path 142 of the main circuit unit 143. This fuse 141 is originally designed to cut off (melt) itself to interrupt the circuit when a current (power) greater than a predetermined value is supplied to the electric motor 58.

[0063] In the work machine 10 of this embodiment, the control unit 130 disconnects the fuse 141 by supplying power from the inverter circuit 144 to the electric motor 58 so that the electric motor 58 does not rotate. For example, when an abnormality occurs somewhere in the main circuit unit 143, power is supplied to the electric motor 58 so that the electric motor 58 does not rotate, and the power consumed by the electric motor 58 at this time is used to disconnect the fuse 141. Note that a branch circuit 146 is connected to the main circuit unit 143. The branch circuit 146 branches off from between the fuse 141 and the inverter circuit 144 in the power path 142 and includes an auxiliary drive unit 157 connected to the fuse 141 in parallel with the inverter circuit 144 (electric motor 58). In other words, a connection unit 148 between the power path 142 and the branch circuit 146 is provided between the inverter circuit 144 (electric motor 58) and the fuse 141 in the power path 142. In other words, a single fuse 141 is disposed between each of the inverter circuit 144 (electric motor 58) and the battery pack 28 and the auxiliary drive unit 157. The auxiliary drive unit 157 is, for example, a solenoid 122. Alternatively, the auxiliary drive unit 157 may include the solenoid 122 and the solenoid drive switch 153.

[0064] Here, the control unit 130 switches the current conduction pattern of the inverter circuit 144 when executing control for normal drive to rotate the electric motor 58, and keeps the current conduction pattern constant when executing control to blow the fuse 141. The current conduction pattern is the ON / OFF pattern of each of six switching elements 144a, 144b, 144c, 144d, 144e, and 144f in the inverter circuit 144 that switches over time (elapsed time).

[0065] For example, the current supply pattern shown in Fig. 4 is a current supply pattern when the control unit 130 performs normal operation to rotate the electric motor 58. Two different combinations of the six switching elements 144a, 144b, 144c, 144d, 144e, and 144f each operate over elapsed time (the horizontal axis in Fig. 4) to supply power to the electric motor 58, thereby rotating the electric motor 58. In Fig. 4, hatched areas indicate that the respective switching elements are in the ON state and operating.

[0066] On the other hand, the current conduction pattern shown in FIG. 5 indicates the current conduction pattern when the control unit 130 performs control to blow the fuse 141. In this current conduction pattern, the switching elements that operate with respect to the elapsed time (the horizontal axis in FIG. 5) are two predetermined switching elements, and only the two predetermined switching elements operate in the ON state regardless of the elapsed time, which is a constant current conduction pattern. In other words, this is a constant current conduction pattern in which the combination of switching elements that operate with respect to the elapsed time does not change. For example, in FIG. 5, only the two hatched switching elements 144a and 144f operate in the ON state regardless of the elapsed time. In this case, since the combination of switching elements that operate with respect to the elapsed time does not change, power is supplied to the electric motor 58, but the electric motor 58 does not rotate.

[0067] In this embodiment, the control unit 130 controls the inverter circuit 144 so that the electric motor 58 does not rotate, which is called a motor lock. When the control unit 130 executes control to blow the fuse 141, the motor is locked and power is supplied to the electric motor 58. For example, when an abnormality occurs in the main body circuit unit 143, the control unit 130 locks the electric motor 58 and supplies a large amount of power to the electric motor 58 using the current pattern shown in FIG. 5, and the power consumed by the electric motor 58 blows the fuse 141. As a result, when an abnormality occurs in the main body circuit unit 143, the power path 142 connecting the battery pack 28 and the electric motor 58 is cut off, thereby preventing the battery pack 28 from over-discharging.

[0068] In this embodiment, a case where the solenoid 122 has a short circuit will be described as an example of an abnormality that occurs in the main circuit unit 143. When an abnormality such as a short circuit occurs in the auxiliary drive unit 157 including the solenoid drive switch (switching element) 153 shown in Fig. 2, the control unit 130 performs control to cut off the fuse 141 as described above.

[0069] However, because the power consumption of the solenoid 122 is small, when a short circuit occurs in the auxiliary drive unit 157, the fuse 141 cannot be blown by the power supplied to the solenoid 122 alone. The power consumption of the electric motor 58 is greater than the power consumption of the auxiliary drive unit (solenoid 122) 157. Therefore, in the work machine 10, a large amount of power is supplied to the electric motor 58 using the current pattern shown in Figure 5, and the fuse 141 is blown by the power consumption of the electric motor 58.

[0070] <Current control during normal operation> 2 are turned on, the control unit 130 starts energizing the electric motor 58 at time t1 (motor start), as shown in Fig. 7. When the electric motor 58 starts to rotate due to the energization of the electric motor 58, the driver blade 54, which has been waiting at the standby position, starts to move upward at time t1.

[0071] When the driver blade 54 reaches the top dead center at time t2 and disengages from the lifting portion 66, it moves toward the bottom dead center due to the biasing force of the striking biasing portion 32 and strikes the nail N. Then, at time t3, the driver blade 54 reaches the bottom dead center. The electric motor 58 continues to rotate, and at time t4, the driver blade 54 and the pinwheel are re-engaged. This causes the driver blade 54 to start moving upward from the bottom dead center. Then, at time t5, the driver blade 54 reaches the standby position and waits there.

[0072] As shown in the motor drive duty in Fig. 7, the drive duty of the supplied power reaches 100% immediately after the motor is started at time t1, and thereafter, power is supplied to the electric motor 58 at 100% duty until the driver blade 54 reaches the standby position at time t5. As shown in Fig. 8, when the driver blade 54 reaches the standby position at time t5, power supply to the electric motor 58 is stopped, and the drive duty of the power supply to the electric motor 58 becomes 0%. Thereafter, at time t6, current is applied to the solenoid 122. That is, as shown in the solenoid current in Fig. 6 and the total current in Fig. 7, the control unit 130 starts applying current to the solenoid 122 at time t6.

[0073] When the solenoid 122 is energized, the feeder 92 (i.e., the solenoid 122) moves in the opposite direction from the ejection unit 42 along the supply direction K1. Then, after the solenoid 122 reaches the ready-to-supply position, the control unit 130 stops energizing the solenoid 122 at time t7, as shown by the solenoid current in FIG. 6 and the total current in FIG. 7. As a result, the solenoid 122 starts to move in the supply direction K1 toward the ejection unit 42 due to the biasing force of the spring 98. Thereafter, the head of the nail N, which has been moved by the feeder 92 toward the ejection unit 42, comes into contact with the driver blade 54, and the movement of the solenoid 122 stops.

[0074] <Detection of solenoid drive failure and constant current control when fuse is blown> 9 is executed to start the electric motor 58 (motor start). Next, "Is the solenoid drive switch OFF?" in step S2 is executed. If the determination in step S2 of "Is the solenoid drive switch OFF?" is NO, "Is the solenoid drive switch OFF?" in step S2 is executed again. If the determination in step S2 of "Is the solenoid drive switch OFF?" is YES, the solenoid drive switch 153 is OFF, so "Is a certain amount of current or more flowing in the solenoid drive unit?" in step S3 is executed.

[0075] If the determination in step S3 of "Is a current above a certain level flowing through the solenoid drive unit?" is NO, step S2 of "Is the solenoid drive switch OFF?" is executed again. If the determination in step S3 of "Is a current above a certain level flowing through the solenoid drive unit?" is YES, step S4 of "Solenoid drive switch failure detected" is executed. That is, since the solenoid current detection circuit 156 detects that a power greater than a predetermined power has been supplied to the solenoid drive switch 153, it is determined that the solenoid drive switch 153 has failed. The failure may be, for example, a short-circuit failure of the solenoid drive switch 153.

[0076] After "solenoid drive switch failure detection" in step S4 shown in Figure 10, "calculation of current value Isolenoid flowing through solenoid drive unit" is executed in step S5. That is, the current [Isolenoid] flowing through solenoid drive switch 153 is calculated. Here, as shown in Figure 11, the magnitude of the power (current) supplied to solenoid 122 after time T0 is [Isolenoid].

[0077] 12, at time T1, power is supplied to the electric motor 58 (motor start-up). The motor current rises to a predetermined magnitude immediately after power is supplied to the electric motor 58, and therefore the inverter circuit 144 is controlled to continue supplying power of a predetermined first magnitude to the electric motor 58 so that the motor locks at time T2 (power is supplied while the motor current is set to a predetermined drive duty).

[0078] Specifically, step S6 in FIG. 10, "the difference between the fuse-cutting currents Ifuse and Isolenoid is passed through the motor", is executed.

[0079] Here, in addition to the current value [Isolenoid] calculated in step S5, a current equal to the difference between the current [Ifuse] that blows the fuse 141 and the calculated [Isolenoid] is passed through the electric motor 58. This current value is set as the target value for the current [Imotor].

[0080] That is, [Imotor] = [Ifuse] - [Isolenoid] (see FIG. 13). Next, "constant current control" is executed in step S7. The target current is [Imotor]. In other words, when blowing the fuse 141, the control unit 130 sets the duty (DUTY) of the current flowing through the inverter circuit 144 so that the sum of the current value (Isolenoid) detected by the solenoid current detection circuit (auxiliary drive unit current detection unit) 156 and the current value (Imotor) detected by the motor current detection circuit (motor current detection unit) 155 becomes a predetermined current value (Ifuse). Here, the duty of the current flowing through the inverter circuit 144 is set to a predetermined magnitude while controlling the current flowing through the inverter circuit 144 so that the motor locks, and the current Imotor is first passed through the electric motor 58 once (the motor current at time T2 in FIG. 12).

[0081] Furthermore, the process executes "Has a certain time TC elapsed?" in step S8 of FIG. 10. If the determination of "Has a certain time TC elapsed?" in step S8 is NO, the certain time TC has not yet elapsed, and thus the "constant current control" in step S7 is executed again. If the determination of "Has a certain time TC elapsed?" in step S8 is YES, this indicates that the fuse 141 has not been blown even after the certain time TC (see FIG. 13) has elapsed, and thus the process executes "update target current" in step S9 (Imotor+α). That is, since [Imotor]+[Isolenoid] does not reach the power required to blow the fuse 141, the current [Imotor] flowing to the electric motor 58 is increased. That is, when the fuse 141 is not blown, the power drive duty (DUTY) supplied to the electric motor 58 is increased at time T3, as shown in FIGS. 12 and 13.

[0082] Next, "Imotor=0?" is executed in step S10 of FIG. 10. If the determination of "Imotor=0?" in step S10 is NO, the motor current has not become 0, so it is determined that the fuse 141 has not been blown. In this case, "Has a certain period of time TC elapsed?" in step S8 is executed again. If the determination of "Imotor=0?" in step S10 is YES, the motor current has become 0, so it is determined that the fuse 141 has been blown (time T4). In other words, the fuse 141 has been blown because [Imotor] + [Isolenoid] has become larger than [Ifuse]. Then, "Stop constant current control" in step S11 is executed and the process ends.

[0083] According to the work machine 10 of this embodiment, when a short-circuit fault of the solenoid drive switch 153 is detected, the control unit 130 controls the inverter circuit 144 to supply power to the electric motor 58 so that the electric motor 58 does not rotate. This causes the fuse 141 provided in the power path 142 of the circuit connecting the battery pack 28 and the electric motor 58 to be blown using the power consumed by the electric motor 58. As a result, the power supply from the battery pack 28 can be cut off.

[0084] This prevents the battery pack 28 from over-discharging even if the solenoid drive switch 153 shorts out. This reduces the frequency of charging the battery pack 28 and extends the life of the battery pack 28. As a result, the convenience of the work machine 10 can be improved.

[0085] Furthermore, if power continues to be supplied to the inverter circuit 144 so that the electric motor 58 does not rotate, there is a possibility that a switching element in the inverter circuit 144 to which power is supplied will malfunction before the fuse 141 is blown. Therefore, when power is supplied to the electric motor 58 so that the electric motor 58 does not rotate, the duty of the power supplied to the inverter circuit 144 is controlled. Here, the power is controlled by applying a duty so that too much current does not flow through the inverter circuit 144. For example, the control unit 130 controls the inverter circuit 144 to lock the motor, and while the motor is locked, power is initially supplied at a small drive duty, and the drive duty is gradually increased. By initially supplying power to the inverter circuit 144 at a small drive duty in this way, it is possible to prevent malfunction of the inverter circuit 144.

[0086] The present invention is not limited to the above-described embodiment and may be modified in various ways without departing from the spirit and scope of the present invention. In other words, other embodiments conceivable within the scope of the technical concept of the present invention are also encompassed within the scope of the present invention. The method by which the control unit 130 supplies power from the inverter circuit 144 to the electric motor 58 to prevent the electric motor 58 from rotating is not limited to the motor lock described above. For example, a brake may be provided that can mechanically lock the rotating shaft of the electric motor 58 when controlled by the control unit 130 so that the electric motor 58 does not rotate even when power is supplied from the inverter circuit 144 to the electric motor 58. Furthermore, the current flow pattern when the control unit 130 locks the motor and supplies power to the electric motor 58 does not have to be the one shown in FIG. 5 . The current flow pattern may be set so that the electric motor 58 repeatedly switches its rotation direction at short intervals, thereby substantially preventing the lifting unit 66 from rotating. The auxiliary drive unit 157 may be any power-consuming component other than the solenoid 122, such as an LED for lighting, a fan for dust collection or cleaning, a display panel for displaying information about the main body, or a communication device for wireless communication with other work machines other than the work machine 10. [Explanation of symbols]

[0087] 10...working machine, 12...housing, 13...cylinder case, 14...motor case, 15...handle, 16...mounting portion, 19...trigger, 28...battery pack (power supply portion), 28a...controller, 28b...cell voltage detection circuit, 28c...cell current detection circuit, 32...impact biasing portion, 36...cylinder, 37...piston chamber, 38...pressure accumulator container, 38a...pressure accumulator chamber, 39...damper, 42...injection portion, 44...push lever, 46...injection port, 47...injection end, 48...impact portion, 52... Piston, 54...driver blade, 56...driver unit, 58...electric motor (motor), 58b...rotor, 62...gear case, 66...lifting part, 70...supply unit, 74...magazine unit, 75...drum unit, 76...guide unit, 78...lid unit, 82...supply path, 84...rotating shaft, 86...claw member, 86a...base, 86b...plate unit, 86c...claw unit, 88...spring, 89...rotating shaft, 92...feeder, 94...movable member, 94a...fixed unit, 94c...shaft unit, 96...feeding member, 96a...first Claw portion, 96b...second claw portion, 98...spring, 120...supply drive portion, 122...solenoid, 124...plunger, 126...supply energizing portion, 130...control portion, 132...rotor position detection circuit, 141...fuse, 142...power path, 143...main body circuit portion, 144...inverter circuit (drive circuit), 144a, 144b, 144c, 144d, 144e, 144f...switching element, 146...branch circuit, 147...control signal output circuit, 148...connection portion, 153...solenoid Solenoid drive switch, 154... battery voltage detection circuit, 155... motor current detection circuit (motor current detection section), 156... solenoid current detection circuit (auxiliary drive section current detection section), 157... auxiliary drive section, 162... push switch, 191... trigger switch, G... mating material, H1... magnetic sensor, K1... supply direction, M... connecting section, N... nail (fastener), R1... direction, TC... certain time, t1, t2, t3, t4, t5, t6, t7... time, T0, T1, T2, T3, T4... time

Claims

1. A motor; a power supply unit that supplies power to the motor; a drive circuit interposed between the power supply unit and the motor in a power path for supplying power from the power supply unit to the motor, the drive circuit controlling the power supplied to the motor; a control unit that controls the drive circuit to control the drive of the motor; a fuse that is interposed between the power supply unit and the drive circuit in the power path and that is capable of interrupting the power path by being blown; The control unit blows the fuse by supplying power from the drive circuit to the motor so that the motor does not rotate.

2. 2. The work machine according to claim 1, wherein the control unit switches the current conduction pattern of the drive circuit when executing control for normal drive to rotate the motor, and keeps the current conduction pattern constant when executing control to blow the fuse.

3. the drive circuit includes a plurality of switching elements; The work machine according to claim 2 , wherein the current conduction pattern is an ON / OFF pattern of each of the plurality of switching elements that changes over time.

4. an auxiliary driving unit that branches off from between the fuse and the driving circuit in the power path and is connected to the fuse in parallel with the driving circuit; The work machine according to claim 1 , wherein the control unit blows the fuse when an abnormality occurs in the auxiliary drive unit.

5. The work machine according to claim 4 , wherein the power consumption of the motor is greater than the power consumption of the auxiliary drive unit.

6. a motor current detection unit that detects a current value flowing through the motor; an auxiliary driving unit current detection unit that detects a current flowing in the auxiliary driving unit; The work machine according to claim 4, comprising:

7. The work machine according to claim 6, wherein the control unit sets the duty of the current flowing through the drive circuit so that, when the fuse is cut, the sum of the current value detected by the auxiliary drive unit current detection unit and the current value detected by the motor current detection unit becomes a predetermined current value.

8. The work machine according to claim 7 , wherein the control unit further increases the duty when the fuse is not blown.

9. The work machine according to claim 4 , wherein the auxiliary drive unit is a solenoid.

10. an injection section to which a fastener is supplied; a striking unit that operates by receiving a driving force from the motor and strikes the fastener supplied to the injection unit; a magazine unit that stores a plurality of the fasteners wound in a roll; The work machine according to claim 4 , further comprising: a supply unit that operates by receiving the driving force of the auxiliary drive unit and supplies the fastener from the magazine unit to the ejection unit.

11. A motor; a power supply unit that supplies power to the motor; a control unit that controls the driving of the motor; an auxiliary driving unit that branches off from a power path that supplies power from the power supply unit to the motor between the power supply unit and the motor, and is connected to the power supply unit in parallel with the motor; a fuse that is interposed between the power supply unit and the motor and the auxiliary drive unit in the power path and that is capable of interrupting the power path by being cut off; an injection section to which a fastener is supplied; a striking unit that operates by receiving a driving force from the motor and strikes the fastener supplied to the injection unit; a magazine unit that stores a plurality of the fasteners wound in a roll; a supply unit that operates by receiving a driving force from the auxiliary drive unit and supplies the fastener from the magazine unit to the ejection unit; Equipped with The control unit blows the fuse when an abnormality occurs in the auxiliary drive unit.

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