Electrically powered work machine

Abstract

The present invention provides a hydraulic excavator (1) comprising an electric motor (7) and a hydraulic actuator. The electric motor (7) is driven by a commercial power source (5) and a battery (62), and the hydraulic actuator is driven by a hydraulic pump (113) driven by the electric motor (7). The electric hydraulic excavator (1) has a first power mode and a second power mode. In the first power mode, the electric motor (7) is driven while the battery (62) is continuously charged from the commercial power source (5). In the second power mode, the electric motor (7) is driven only by the battery (62). When the power supply cable (51) for power supply from the commercial power source (5) is connected to the power supply port and the rotation of the electric motor (7) stops, the excavator switches from the second power mode to the first power mode.

Description

Technical Field

[0001] This invention relates to electric work machinery. Background Technology

[0002] Patent Document 1 discloses a construction machine equipped with a power system that uses commercial power and batteries to drive an electric motor. The power system includes: a circuit that supplies DC power from the battery to an inverter that converts the DC power into arbitrary AC power and supplies it to the electric motor; and a power switching device that switches the AC power supplied from the commercial power source to DC power via an AC-DC converter and supplies it to the inverter.

[0003] Patent Document 2 discloses the following technology: providing an electric excavator having a mode in which the electric motor is driven while the battery is being charged from an external power source, and a mode in which the electric motor is driven using only the battery. In the mode in which the electric motor is driven using only the battery, the mode in which the electric motor is driven while the battery is being charged from an external power source is switched by connecting to an external power source.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-228715,

[0005] Patent Document 2: Japanese Patent Application Publication No. 2008-308881.

[0006] However, in Patent Document 1, because a commercial power source and battery are chosen, when the electric motor is driven using only electricity from the commercial power source, the power to drive the electric motor depends on the commercial power source, thus causing a problem where sufficient driving force cannot be obtained in operations requiring greater driving force. Furthermore, in Patent Document 2, because the machine is connected to a power supply cable for supplying external power when driven solely by a battery, there is a risk of arcing. Moreover, the behavior of the power supply cable connected to the machine when driven solely by a battery could potentially induce contact accidents due to the machine's rotation or movement. Summary of the Invention

[0007] Therefore, in view of the above-mentioned problems, the present invention aims to provide an electric working machine that suppresses the behavior of connecting the machine to a power supply cable from an external power source during operation, and prevents the occurrence of arc discharge even when the power supply cable is connected.

[0008] The electric work machine of the present invention includes an electric motor and a hydraulic actuator. The electric motor is driven by an external power source and a battery, and the hydraulic actuator uses a hydraulic pump driven by the electric motor as its hydraulic source.

[0009] This electric work machine has a first power mode and a second power mode. In the first power mode, the electric motor is driven while the battery is continuously charged from the external power source. In the second power mode, the electric motor is driven solely by the battery.

[0010] When the power supply cable for the external power supply is connected to the power supply port and the rotation of the electric motor stops, the system switches from the second power supply mode to the first power supply mode.

[0011] In this invention, when the power supply cable for the external power supply is connected to the power supply port, the rotation of the electric motor is stopped, and the operation of the hydraulic actuator is restricted by rotating the cutting rod upward, the power supply mode can be switched from the second power mode to the first power mode. In this mode, the cutting rod restricts the operation of the hydraulic actuator by cutting off the pilot pressure for operating the hydraulic actuator.

[0012] In this invention, the power supply cable can be disconnected from the power supply port, and the power supply mode can be switched from the first power supply mode to the second power supply mode.

[0013] According to the present invention, if the rotation of the electric motor does not stop, the switch from the second power supply mode to the first power supply mode is not made, thus suppressing the behavior of the power supply cable connected to the external power supply during operation, and preventing arc discharge even when the power supply cable is connected. Attached Figure Description

[0014] Figure 1 This is a side view showing the electric work machine of this embodiment.

[0015] Figure 2 It is a magnified side view showing the perimeter of the cutting rod of the electric operating machine.

[0016] Figure 3 This is a diagram showing the hydraulic circuit of an electric work machine.

[0017] Figure 4 This is a block diagram of the power supply system mounted on an electric work machine.

[0018] Figure 5A This is a block diagram of a power system that implements a commercial power supply mode.

[0019] Figure 5B This is a block diagram of a power supply system that implements a 2-way mode.

[0020] Figure 5C This is a block diagram of a power system that implements battery mode.

[0021] Figure 5DThis is a block diagram of a power system that implements the charging mode.

[0022] Figure 6 This is a flowchart illustrating the sequence of power mode switching controls.

[0023] Figure 7 This is a flowchart showing the sequence of switching control between 2-way mode and battery mode.

[0024] Figure 8 This is a flowchart illustrating the sequence of switching control between two-way mode and battery mode in another embodiment. Detailed Implementation

[0025] The following is a reference to the appendix. Figure 1 The embodiments of the present invention will be described below.

[0026] [Structure of Electric Work Machinery]

[0027] First, refer to Figure 1 and Figure 2 The general structure of a hydraulic excavator 1, an example of an electric working machine, will be described below. Note that the electric working machine is not limited to a hydraulic excavator 1; it could also be other vehicles such as wheel loaders. The hydraulic excavator 1 includes a lower traveling body 2, a working body 3, and an upper rotating body 4.

[0028] The lower traveling body 2 has a pair of left and right tracks 21, 21 and a pair of left and right travel motors 22L, 22R. The hydraulic motors, i.e., the left and right travel motors 22L, 22R, drive the left and right tracks 21, 21 respectively, thereby enabling the hydraulic excavator 1 to move forward and backward. In addition, the lower traveling body 2 is provided with blades 23 and hydraulic cylinders, i.e., blade cylinders 23a, for rotating the blades 23 in the up and down direction.

[0029] The excavator 3 has a boom 31, a stick 32, and a bucket 33. By driving them independently, it can perform excavation operations such as digging soil and sand. The boom 31, stick 32, and bucket 33 are respectively equivalent to working parts, and the hydraulic excavator 1 has multiple working parts.

[0030] The base end of the boom 31 is supported on the front of the upper rotating body 4 and rotates via a boom cylinder 31a that can move freely telescopically. Similarly, the base end of the stick 32 is supported on the front end of the boom 31 and rotates via a stick cylinder 32a that can move freely telescopically. Furthermore, the base end of the bucket 33 is supported on the front end of the stick 32 and rotates via a bucket cylinder 33a that can move freely telescopically. The boom cylinder 31a, stick cylinder 32a, and bucket cylinder 33a are all hydraulic cylinders.

[0031] The upper rotating body 4 is configured to rotate relative to the lower traveling body 2 via a rotary bearing (not shown). The upper rotating body 4 is equipped with an operating unit 41, a rotating platform 42, a rotary motor 43, and a battery 62. The upper rotating body 4 is rotated via the rotary bearing (not shown) using the driving force of the hydraulic motor, i.e., the rotary motor 43. Furthermore, the upper rotating body 4 is equipped with multiple hydraulic pumps driven by electric motors (in... Figure 1 (Not shown in the diagram). These hydraulic pumps supply pressurized oil to each hydraulic motor (travel motors 22L, 22R, and rotary motor 43) and each hydraulic cylinder (vane cylinder 23a, boom cylinder 31a, stick cylinder 32a, and bucket cylinder 33a). Each hydraulic motor and each hydraulic cylinder is collectively referred to as a hydraulic actuator.

[0032] A control seat 411 is provided in the control unit 41. A pair of operating levers 412L and 412R are arranged on the left and right sides of the control seat 411, and a pair of travel levers 413L and 413R are arranged in front of it. The operator operates the operating levers 412L and 412R and the travel levers 413L and 413R by sitting on the control seat 411, thereby controlling the hydraulic actuators and performing travel, rotation, and operation.

[0033] Furthermore, the operating levers 412L and 412R are integrally mounted on the lever bracket 414, and the cutting lever 415 extends forward from the lever bracket 414. The cutting lever 415 is used to connect or disconnect the operation of the operating levers 412L and 412R on the machine 3. The cutting lever 415 is configured to rotate vertically. When rotated downwards, the machine 3 operates based on the operation of the operating levers 412L and 412R; when rotated upwards, the machine 3 is locked in a locked state where it does not operate even when the operating levers 412L and 412R are operated. A cut-off switch 416 is provided inside the lever bracket 414 to detect the rotational position of the cutting lever 415. The cut-off switch 416 is configured to connect when the cutting lever 415 rotates downwards and disconnect when the cutting lever 415 rotates upwards.

[0034] A power supply port (not shown) is provided on the upper rotating body 4. By connecting the power supply cable 51 of the commercial power supply 5 (equivalent to an external power supply) to the power supply port, the commercial power supply 5 can be connected to the power system 6 described later.

[0035] The hydraulic pump that supplies pressurized oil to the hydraulic actuator is configured to operate via an electric motor driven by electricity, with commercial power supply 5 and battery 62 supplying power to the electric motor.

[0036] [Composition of Hydraulic Circuit]

[0037] Figure 3The hydraulic circuit 100 mounted on the hydraulic excavator 1 is shown. The hydraulic circuit 100 includes a first actuator 111, a second actuator 112, a hydraulic pump 113, a pilot pump 114, a first directional switching valve 115, a second directional switching valve 116, and an operating device 117.

[0038] The first actuator 111 is a hydraulic motor driven by pressurized oil supplied from the hydraulic pump 113. The first actuator 111 is, for example, a travel motor 22L or 22R. The second actuator 112 is a hydraulic cylinder driven by pressurized oil supplied from the hydraulic pump 113. The second actuator 112 is, for example, a boom cylinder 31a.

[0039] Hydraulic pump 113 is driven by an electric motor (not shown) to discharge pressurized oil. The pressurized oil discharged from hydraulic pump 113 is supplied to the first directional switching valve 115 and the second directional switching valve 116 via oil passages 113a and 113b. Furthermore, in Figure 3 In the diagram, the oil passages from the hydraulic pump 113 to the first actuator 111 and the second actuator 112 are represented by solid lines.

[0040] The first directional switching valve 115 is a pilot-operated directional switching valve capable of switching the direction of the pressurized oil supplied to the first actuator 111 and regulating the flow rate. The second directional switching valve 116 is a pilot-operated directional switching valve capable of switching the direction of the pressurized oil supplied to the second actuator 112 and regulating the flow rate.

[0041] Pilot pump 114 discharges pilot pressure oil, which is input as a command to the first directional switching valve 115 and the second directional switching valve 116. Figure 3 In the diagram, the oil passage for pilot pressure oil supplied from pilot pump 114 to second directional switching valve 116 is shown as a dashed line (the oil passage for pilot pressure oil supplied from pilot pump 114 to first directional switching valve 115 is not shown). Pilot pump 114 generates pilot pressure applied to first directional switching valve 115 and second directional switching valve 116. Pilot pump 114 is driven by an electric motor (not shown) and generates pilot pressure in oil passage 114a by discharging pressurized oil.

[0042] The first directional switching valve 115 can be switched to multiple positions by sliding the spool valve. When no pilot pressure is applied to either pilot port 115a or pilot port 115b of the first directional switching valve 115, the first directional switching valve 115 is held in the neutral position by the force of a spring. When the first directional switching valve 115 is in the neutral position, pressurized oil is not supplied from the oil passage 113b to the first actuator 111.

[0043] On the other hand, when a pilot pressure is applied to either the pilot port 115a or the pilot port 115b of the first directional switching valve 115, the first directional switching valve 115 switches from a neutral position to another position, and pressurized oil is supplied to the first actuator 111 via oil passage 111a or oil passage 111b. The first actuator 111 is driven to rotate in the forward or reverse direction by the pressurized oil supplied via oil passage 111a or oil passage 111b.

[0044] The second directional switching valve 116 can be switched to multiple positions by sliding the spool valve. When no pilot pressure is applied to either pilot port 116a or pilot port 116b of the second directional switching valve 116, the second directional switching valve 116 is held in the neutral position by the force of a spring. When the second directional switching valve 116 is in the neutral position, pressurized oil is not supplied from oil passage 113a to the second actuator 112.

[0045] On the other hand, when a pilot pressure is applied to either the pilot port 116a or the pilot port 116b of the second directional switching valve 116, the second directional switching valve 116 switches from the neutral position to another position, and pressurized oil is supplied to the second actuator 112 via oil passage 112a or oil passage 112b. The second actuator 112 extends and retracts due to the pressurized oil supplied via oil passage 112a or oil passage 112b.

[0046] The operating device 117 includes a remote control valve 117a for switching the direction and pressure of pilot pressure oil supplied to the second direction switching valve 116. The operating device 117 is, for example, an operating lever 412L or 412R. The remote control valve 117a is connected to oil passage 114a. Furthermore, the remote control valve 117a is connected to the pilot ports 116a and 116b of the second direction switching valve 116 via oil passages 117b and 117c, respectively. The remote control valve 117a supplies pressure oil supplied from the pilot pump 114 via oil passage 114a as pilot pressure oil to the second direction switching valve 116. By operating the operating device 117, the second direction switching valve 116 can be switched, the direction of the pressure oil supplied to the second actuator 112 can be switched, and the flow rate can be adjusted.

[0047] An on / off valve 180 is installed in the oil passage 114a between the pilot pump 114 and the remote control valve 117a. The on / off valve 180 is a solenoid valve and includes a solenoid tube 180a. The solenoid tube 180a is connected to the cut-off switch 416. Figure 3 As shown, when the cutting rod 415 rotates downwards to close the cutting switch 416, the solenoid 180a is energized, making the on / off valve 180 in the connected state. Thus, pressurized oil from the pilot pump 114 is supplied to the remote control valve 117a via the on / off valve 180. On the other hand, if like... Figure 3When the cutting lever 415 is rotated upwards as shown by the double-dotted line, the cutting switch 416 is disconnected due to the spring force, and the solenoid 180a is no longer energized. The opening and closing valve 180 is also in the closed state due to the spring force. As a result, the pressurized oil from the pilot pump 114 is not supplied to the remote control valve 117a, and even if the operating device 117 is operated, no pilot pressure is applied to the second direction switching valve 116. Therefore, no pressurized oil is supplied to the second actuator 112, and the operation of the second actuator 112 is restricted. Thus, if the cutting lever 415 is rotated downwards, the machine 3 can operate based on the operation of the operating device 117; if it is rotated upwards, the machine 3 is locked in a locked state where it does not operate even if the operating device 117 is operated.

[0048] [Power System Composition]

[0049] use Figure 4 The power supply system 6, which is mounted on the hydraulic excavator 1 and supplies power to the electric motor 7, will be described. The power supply system 6 includes: a power supply unit 61, which converts the AC power supply voltage of the commercial power supply 5 into a DC power supply voltage; a battery 62, which charges or discharges the power from the power supply unit 61; an inverter 63, which converts the DC power supply voltage into an AC power supply voltage; a first circuit 6a, which supplies power from the power supply unit 61 to the inverter 63; a second circuit 6b, which combines the power from the battery 62 and the first circuit 6a; an inverter relay 64, which is disposed between the junction point 6c of the first circuit 6a and the second circuit 6b and the inverter 63; a battery relay 65, which is disposed between the junction point 6c and the battery 62; and a power supply relay 66, which is disposed between the junction point 6c and the power supply unit 61.

[0050] Power supply unit 61 converts the AC voltage supplied from commercial power supply 5 via power supply cable 51 into DC voltage. This DC voltage is supplied to battery 62 via power supply relay 66 and battery relay 65 to charge battery 62. In addition, the DC voltage from power supply unit 61 is supplied to inverter 63 via power supply relay 66 and inverter relay 64.

[0051] Battery 62 supplies DC voltage to inverter 63 via battery relay 65 and inverter relay 64. A lithium-ion battery is shown as an example of battery 62.

[0052] Inverter 63 converts the DC voltage supplied from power supply 61 and / or battery 62 into AC voltage. This AC voltage is supplied to electric motor 7. Electric motor 7 operates hydraulic pump 113. Furthermore, in Figure 4 Only hydraulic pump 113 is shown in the diagram, but multiple hydraulic pumps can also be installed.

[0053] In addition, the power system 6 includes a system controller 67 for controlling the power system 6. The system controller 67 performs power supply control to the electric motor 7, charging control of the battery 62, etc. More specifically, the system controller 67 can drive the electric motor 7 or charge the battery 62 by controlling the power supply unit 61, inverter 63, inverter relay 64, battery relay 65, power supply relay 66, etc.

[0054] Power system 6 has Figures 5A to 5D The multiple power modes are shown. For example... Figure 5A As shown, by engaging the contacts of inverter relay 64 and power supply relay 66 and disengaging the contacts of battery relay 65, power system 6 can be configured to operate in a commercial power mode, where the electric motor 7 is driven solely by power supplied from commercial power supply 5. This reduces the frequency of battery 62 usage and extends its lifespan. Furthermore, even if battery 62 malfunctions, operation can continue via commercial power supply 5 as long as the system is in commercial power mode.

[0055] In addition, such as Figure 5B As shown, the power system 6 can form a dual-mode (equivalent to the first power mode) by making the three contacts of inverter relay 64, power supply relay 66 and battery relay 65 in contact, so that the electric motor 7 can be driven by power supplied from battery 62 and commercial power supply 5.

[0056] In addition, such as Figure 5C As shown, the power system 6 can be configured to drive the electric motor 7 by supplying power solely from the battery 62 (equivalent to the second power mode) by contacting the contacts of the inverter relay 64 and the battery relay 65 and disconnecting the contacts of the power supply relay 66.

[0057] In addition, such as Figure 5D As shown, the power system 6 can form a charging mode in which only the commercial power supply 5 charges the battery 62 by contacting the contacts of the battery relay 65 and the power supply relay 66 and disconnecting the contacts of the inverter relay 64.

[0058] Next, the control method for switching the power mode described above will be explained. Figure 6 This is a flowchart illustrating the sequence of power mode switching control. First, the operator turns on the power. Next, the operator selects the power mode using the power mode selection switch. In step S1, it is determined which power mode has been selected. If mode 1 is selected, the system controller 67 turns on the inverter relay 64 and the power supply relay 66, and turns off the battery relay 65, thus switching to commercial power mode.

[0059] On the other hand, if mode 2 or mode 3 is selected in step S1, in the next step S2, it is determined whether the power supply 61 can be used. The power supply 61 has a control unit that determines whether it can be used. If it cannot be used, it sends an error signal to the system controller 67. When the system controller 67 receives the error signal from the power supply 61, it determines that the power supply 61 is unusable.

[0060] If the power supply 61 is determined to be "unusable" in step S2, the next step S3 determines whether the battery 62 is usable. The battery 62 has a control unit that determines whether it is usable. If it is unusable, it sends an error signal to the system controller 67. Upon receiving the error signal from the battery 62, the system controller 67 determines that the battery 62 is unusable. If the battery 62 is determined to be "unusable" in step S3, the system controller 67 issues an error report.

[0061] On the other hand, if the battery 62 is determined to be "usable" in step S3, the system controller 67 will turn on the battery relay 65 in the next step S4. Next, in step S5, it is determined whether the inverter 63 is usable. The inverter 63 has a control unit that determines whether it is usable; if it is not usable, it sends an error signal to the system controller 67. Upon receiving the error signal from the inverter 63, the system controller 67 determines that the inverter 63 is not usable. If the inverter 63 is determined to be "not usable" in step S5, the system controller 67 will issue an error report.

[0062] On the other hand, if it is determined in step S5 that the inverter 63 is "usable", in the next step S6, the system controller 67 turns on the inverter relay 64. This enables a battery mode (second power mode) where the electric motor 7 is driven solely by power supplied from the battery 62.

[0063] If the power supply 61 is determined to be "usable" in step S2, the system controller 67 determines whether the battery 62 is usable in the next step S7. If the battery 62 is determined to be "unusable" in step S7, the system controller 67 issues an error report. On the other hand, if the battery 62 is determined to be "usable" in step S7, the system controller 67 activates the battery relay 65 in the next step S8.

[0064] Next, in step S9, it is determined which power mode has been selected. If mode 3 has been selected, in the next step S10, the connection of the power supply cable 51 is confirmed. If the power supply cable 51 is connected to the power supply port, the power supply unit 61 detects this and sends a connection signal to the system controller 67. Upon receiving the connection signal from the power supply unit 61, the system controller 67 determines that the power supply cable 51 is connected to the power supply port. If, in step S10, the power supply cable 51 is determined to be "not connected," the system controller 67 issues an error report.

[0065] On the other hand, if it is determined in step S10 that the power supply cable 51 is "connected", the power supply relay 66 is turned on in the next step S11. This enables a charging mode in which only the commercial power supply 5 charges the battery 62.

[0066] If mode 2 is selected in step S9, the system controller 67 determines whether inverter 63 can be used in the next step S12. If inverter 63 cannot be used, the system controller 67 issues an error report. On the other hand, if inverter 63 is determined to be usable in step S12, the system controller 67 activates inverter relay 64 in the next step S13.

[0067] Next, in step S14, the connection of the power supply cable 51 is confirmed. If it is determined in step S14 that the power supply cable 51 is "not connected", the system enters battery mode (second power mode) where power is supplied only from the battery 62 to drive the electric motor 7.

[0068] On the other hand, if it is determined in step S14 that the power supply cable 51 is "connected", the power supply relay 66 is turned on in the next step S15. This enables a dual-mode (first power mode) where power is supplied from the battery 62 and the commercial power supply 5 to drive the electric motor 7.

[0069] Next, use Figure 7 The control method for switching between dual-mode and battery mode is explained. In battery mode, step S16 checks the connection of the power supply cable 51. If step S16 determines that the power supply cable 51 is "not connected," the battery mode continues.

[0070] On the other hand, if the power supply cable 51 is determined to be "connected" in step S16, the system determines in the next step S17 whether the rotation of the electric motor 7 has stopped. Since the electric motor 7 is equipped with a position sensor, the inverter 63 receives information from the position sensor, calculates the rotational speed of the electric motor 7, and sends this rotational speed information to the system controller 67. The system controller 67 can determine whether the rotation of the electric motor 7 has stopped based on the rotational speed information received from the inverter 63. If the system determines "no" in step S17 that the rotation of the electric motor 7 has not stopped, the battery mode continues.

[0071] On the other hand, if the determination in step S17 indicates that the rotation of the electric motor 7 has stopped ("yes"), then in the next step S18, the power supply relay 66 is turned on. This enables switching from battery mode to dual-channel mode.

[0072] Additionally, in 2-way mode, in step S19, the connection of the power supply cable 51 is confirmed. If the power supply cable 51 is determined to be "connected" in step S19, the 2-way mode continues.

[0073] On the other hand, if it is determined in step S19 that the power supply cable 51 is "not connected", the power supply relay 66 is disconnected in the next step S20. This enables switching from 2-way mode to battery mode.

[0074] [Other Implementation Methods]

[0075] like Figure 8 As shown, during the switch from battery mode to dual-mode, in addition to confirming the connection of the power supply cable 51 and the stop of the rotation of the electric motor 7, it can also determine whether the operation of the hydraulic actuator is restricted by rotating the cutting lever 415 upwards. The system controller 67 can determine whether the cutting lever 415 is rotating upwards based on the information sent from the cut-off switch 416 regarding whether the cutting lever 415 is rotating upwards or downwards. If the determination is "yes" in step S17, it is determined in the next step S21 whether the cutting lever 415 is rotating upwards. If the determination is "no" in step S21, indicating that the cutting lever 415 is not rotating downwards, the battery mode continues. On the other hand, if the determination is "yes" that the cutting lever 415 is rotating upwards, the power supply relay 66 is turned on in the next step S18.

[0076] The embodiments of the present invention have been described above based on the accompanying drawings, but it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is not only indicated by the description of the above embodiments, but also by the claims, and includes all modifications within the same meaning and scope as the claims.

[0077] Explanation of reference numerals in the attached figures

[0078] 1…Hydraulic excavator; 5…Commercial power supply; 51…Power cable; 6…Power system; 7…Electric motor; 62…Battery; 112…Second actuator; 113…Hydraulic pump; 415…Cut-off rod.

Claims

1. An electric operating machine comprising an electric motor and a hydraulic actuator, wherein the electric motor is driven by an external power source and a battery, and the hydraulic actuator uses a hydraulic pump driven by the electric motor as its hydraulic source. The electric work machine has a first power mode and a second power mode. In the first power mode, the battery continues to be charged from the external power source while the electric motor is driven. In the second power mode, the electric motor is driven solely by the battery. When the power cable for the external power supply is connected to the power port and the electric motor has stopped rotating, the system switches from the second power mode to the first power mode. In a case where the power supply cable for the external power supply is connected to the power supply port, and the rotation of the electric motor is stopped, and the cut-off lever is turned upward to restrict the operation of the hydraulic actuator, the second power supply mode is moved to the first power supply mode, wherein The cut-off lever restricts the operation of the hydraulic actuator by cutting off the pilot pressure that operates the hydraulic actuator.

2. The electric work machinery according to claim 1, wherein, When the power supply cable is disconnected from the power supply port, the system switches from the first power mode to the second power mode.

3. The electric work machinery according to claim 1 or 2, wherein, The electric motor can use the external power source as its driving power source via the power supply cable.

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