Electric power tool

Abstract

An electric work machine (1) comprises: a battery unit (30); an electric motor (9); an inverter (38) that supplies power from the battery unit to the electric motor and drives the electric motor; hydraulic pumps (P1, P2) that are actuated by the motive power of the electric motor; a hydraulic device that is actuated by the hydraulic pressure of hydraulic oil discharged from the hydraulic pumps; an oil temperature detection device (44) for detecting the temperature of the hydraulic oil; a rotation speed detection device (42) for detecting the rotation speed of the electric motor; and a control device (7) that controls driving of the inverter and the electric motor. The control device gradually increases the rotation speed of the electric motor and sets the rotation speed to a target rotation speed so that the time until the rotation speed of the electric motor reaches the target rotation speed when the electric motor is started while the temperature of the hydraulic oil detected by the oil temperature detection device is equal to or less than a predetermined temperature is longer than when the electric motor is started while the temperature of the hydraulic oil is higher than the predetermined temperature.

Description

Technical Field

[0001] The present invention relates to a power-operated work machine driven by the power of an electric motor.

Background Art

[0002] For example, Patent Document 1 discloses a power-operated work machine driven by the power of an electric motor. The power-operated work machine disclosed in Patent Document 1 includes a battery unit, an electric motor driven by the power output from the battery unit, an inverter connected to the battery unit and the electric motor and adjusting the power output to the electric motor, a hydraulic pump driven by the electric motor to discharge hydraulic oil, a hydraulic device driven by the hydraulic oil discharged from the hydraulic pump, a control device that controls the rotational speed of the electric motor according to the current value output from the battery unit or the inverter, and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The power-operated work machine is equipped with an electric motor as a prime mover. However, since the electric motor does not have changes in output caused by hydraulic oil and the temperature of the internal combustion engine (engine) like those in an internal combustion engine, the rotational speed of the electric motor increases all at once to the target rotational speed at startup. However, when the temperature of the hydraulic oil is low and the kinematic viscosity is high, if the electric motor is started and the rotational speed of the electric motor is increased all at once to a high rotational speed, the hydraulic pump will operate suddenly, the suction negative pressure will increase, and cavitation may occur. When cavitation occurs in the hydraulic oil such as inside the hydraulic pump, the hydraulic pump will wear out, leading to a shortened service life of the hydraulic pump.

[0005] The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to suppress the occurrence of cavitation in the hydraulic oil in a power-operated work machine.

Means for Solving the Problems

[0006] A power-operated work machine according to one aspect of the present invention includes a battery unit, an electric motor, an inverter that supplies power of the battery unit to the electric motor to drive the electric motor, a hydraulic pump that operates by the power of the electric motor, a hydraulic device that operates by the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump, an oil temperature detection device that detects the temperature of the hydraulic oil, a rotation speed detection device that detects the rotation speed of the electric motor, and a control device that controls the driving of the inverter and the electric motor. A storage device that stores in advance control data indicating a change in the rotational speed of the electric motor to stabilize the rotational speed of the electric motor at a predetermined target rotational speed with a predetermined delay time; When starting the electric motor in a state where the temperature of the hydraulic oil detected by the oil temperature detection device is equal to or lower than a predetermined temperature, the control device makes the time until the rotation speed of the electric motor reaches the target rotation speed longer than when starting the electric motor in a state where the temperature of the hydraulic oil is higher than the predetermined temperature. Based on the control data The rotation speed of the electric motor is gradually increased.

[0007] Also, according to another aspect of the present invention The power-operated work machine includes A battery unit, an electric motor, an inverter that supplies power from the battery unit to the electric motor to drive the electric motor, a hydraulic pump that operates by the power of the electric motor, a hydraulic device that operates by the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump, an oil temperature detection device that detects the temperature of the hydraulic oil, a rotational speed detection device that detects the rotational speed of the electric motor, an instruction member that is operated to instruct the rotation speed of the electric motor And a control device that controls the driving of the inverter and the electric motor; When starting the electric motor in a state where the temperature of the hydraulic oil is equal to or lower than a predetermined temperature, the control device determines a delay time until the rotation speed of the electric motor stabilizes at the target rotation speed, using the rotation speed instructed by the instruction member as the target rotation speed, and gradually increases the rotation speed of the electric motor so that the rotation speed of the electric motor stabilizes at the target rotation speed after the elapse of the delay time from when the rotation speed of the electric motor starts to increase. are aimed at

[0008]

[0009] The control device may calculate the target rotation speed according to the operation position of the instruction member.

[0009] ​ The electric working machine includes a storage device in which basic control data indicating a change in the rotational speed of the electric motor is stored in advance to stabilize the rotational speed of the electric motor at a predetermined basic target rotational speed with a predetermined basic delay time. When the control device changes the rotational speed of the electric motor based on the basic control data, the control device may determine the time until the rotational speed of the electric motor reaches the target rotational speed as the delay time.

[0010] The basic control data is curvilinear data indicating the correlation between the elapsed time from the start point of the increase in the rotational speed of the electric motor and the rotational speed of the electric motor, and includes a basic end point at which the elapsed time is the basic delay time and the rotational speed of the electric motor is the basic target rotational speed. The control device corrects the basic control data so that the basic end point coincides with the target end point at which the elapsed time is the delay time and the rotational speed of the electric motor is the target rotational speed, thereby creating control data indicating the change in the rotational speed of the electric motor to stabilize the rotational speed of the electric motor at the target rotational speed with the delay time, and may control the rotational speed of the electric motor based on the control data.

[0011] The basic target rotational speed is set to a predetermined maximum rotational speed that can be set for the electric motor. The control device may create the control data by reducing and correcting the basic control data so that the basic end point coincides with the target end point.

[0012] The indicating member can indicate target rotational speeds at a plurality of predetermined levels. the The electric working machine includes a storage device in which, for each of the target rotational speeds at the plurality of levels, a corresponding delay time and control data indicating the change in the rotational speed of the electric motor to stabilize the rotational speed of the electric motor at the corresponding target rotational speed with the corresponding delay time are stored in advance. The control device may control the rotational speed of the electric motor based on the control data corresponding to any one of the target rotational speeds indicated by the indicating member. the target rotational speeds at a plurality of levels. the The electric working machine includes a storage device in which, for each of the target rotational speeds at the plurality of levels, a corresponding delay time and control data indicating the change in the rotational speed of the electric motor to stabilize the rotational speed of the electric motor at the corresponding target rotational speed with the corresponding delay time are stored in advance. The control device may control the rotational speed of the electric motor based on the control data corresponding to any one of the target rotational speeds indicated by the indicating member.

[0013] When gradually increasing the rotational speed of the electric motor to stabilize it at the target rotational speed, the control device compares the actual rotational speed of the electric motor detected by the rotational speed detection device with the control value of the rotational speed of the electric motor indicated by the control data at each predetermined timing, and may control the rotational speed of the electric motor so that the actual rotational speed approaches the control value.

[0014] Among the immediately-after-start section, the middle section, and the immediately-before-end section obtained by dividing the section from the start point of the increase in the rotational speed of the electric motor to the delay time, in the middle section, the rotational speed of the electric motor may be increased in proportion to the elapsed time from the start point of the increase, and in the immediately-after-start section and the immediately-before-end section, the rotational speed of the electric motor may be changed more gently than in the middle section.

[0015] The electric working machine includes a working device that operates by the power of the hydraulic equipment and an operation member that operates the operation of the working device. In the immediately-after-start section, the control device may prohibit the operation of the working device by the operation of the operation member.

[0016] When the control device is increasing the rotational speed of the electric motor according to the control data, if the indicating member is operated, a new the target rotational speed is determined according to the operation position of the indicating member, the new and if the target rotational speed is greater than the actual rotational speed of the electric motor detected by the rotational speed detection device, the new the delay time and the control data may be changed according to the target rotational speed, and the rotational speed of the electric motor may be controlled according to the changed control data.

[0017] The electric working machine may include a display device that displays a notification suggesting that the electric motor is starting during the gradual increase in the rotational speed of the electric motor by the control device.

Advantages of the Invention

[0018] According to the above configuration, it is possible to suppress the occurrence of cavitation in the hydraulic oil in the electric working machine.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] First, the overall configuration of the electric working machine 1 of the present embodiment will be described. FIG. 9 is an overall side view of the electric working machine 1. The electric working machine 1 is an excavator called a backhoe. The electric working machine 1 includes a machine body (swivel base) 2, a traveling device 10, a working device 20, etc. Further, the electric working machine 1 includes an electric motor 9 (FIG. 1) as a prime mover, and operates by the power of the electric motor 9.

[0022] On the body 2 of the electric working machine 1, there are provided a driver's seat 4 on which an operator (worker) sits, and a protection mechanism 6 that protects the driver's seat 4 from the front, rear, left, right, and above. The protection mechanism 6 is called a cabin. On each side surface of the protection mechanism 6, there is provided a transparent portion (so-called window) through which the surroundings can be visually observed from the driver's seat 4. The protection mechanism 6 partitions the internal space where the driver's seat 4 is provided from the outside.

[0023] Around the driver's seat 4 inside the protection mechanism 6, there is provided an operating device 5 for operating the electric working machine 1. The operator can operate the operating device 5 while sitting on the driver's seat 4. In the present embodiment, the side of the working device 20 (in the direction of arrow A1 in FIG. 9) with respect to the protection mechanism 6 is defined as the front, and the opposite side (in the direction of arrow A2 in FIG. 9) is defined as the rear for explanation. Also, the horizontal direction orthogonal to the front-rear direction is defined as the width direction for explanation. Further, in the state facing forward A1, the left side is defined as the left and the right side is defined as the right for explanation.

[0024] The traveling device 10 supports the body 2 so as to be capable of traveling. The traveling device 10 has a traveling frame (truck frame) 11 and a traveling mechanism 12. The traveling frame 11 is a structure that attaches the traveling mechanism 12 around it and supports the body 2 on its upper part. The traveling mechanism 12 is, for example, a crawler-type traveling mechanism. The traveling mechanisms 12 are respectively provided on the left side and the right side of the traveling frame 11. The traveling mechanism 12 has idlers 13, drive wheels 14, a plurality of roller wheels 15, an endless crawler belt 16, and traveling motors ML, MR.

[0025] The idler 13 is disposed at the front part of the traveling frame 11. The drive wheel 14 is disposed at the rear part of the traveling frame 11. The plurality of roller wheels 15 are provided between the idler 13 and the drive wheel 14. The crawler belt 16 is wound around the idler 13, the drive wheel 14, and the roller wheels 15.

[0026] The left traveling motor ML is included in the traveling mechanism 12 on the left side of the traveling frame 11. The right traveling motor MR is included in the traveling mechanism 12 on the right side of the traveling frame 11. These traveling motors ML and MR are composed of hydraulic motors. In each traveling mechanism 12, the driving wheels 14 are rotationally driven by the power of the traveling motors ML and MR to circulate the crawler belt 16 in the circumferential direction.

[0027] A dozer device 18 is mounted on the front part of the traveling device 10. The dozer device 18 swings up and down by the extension and contraction of the dozer cylinder C5. The dozer cylinder C5 is attached to the traveling frame 11. The dozer cylinder C5 is composed of a hydraulic cylinder.

[0028] The machine body 2 is rotatably supported around the turning axis X via a slewing bearing 3 on the traveling frame 11. A slewing motor MT is provided inside the machine body 2. The slewing motor MT is composed of a hydraulic motor (a hydraulic actuator included in hydraulic equipment). The machine body 2 turns around the turning axis X by the power of the slewing motor MT.

[0029] The working device 20 is supported on the front part of the machine body 2. The working device 20 has a boom 21, an arm 22, a bucket (working tool) 23, and hydraulic cylinders C1 to C5. The base end side of the boom 21 is pivotally attached to a swing bracket 24 so as to be rotatable around a horizontal axis (an axis extending in the width direction of the machine body 2). Therefore, the boom 21 can swing in the vertical direction (the vertical direction). The arm 22 is pivotally attached to the tip end side of the boom 21 so as to be rotatable around a horizontal axis. Therefore, the arm 22 can swing in the front-rear direction or the vertical direction. The bucket 23 is provided on the tip end side of the arm 22 so as to be capable of performing a curl operation and a dump operation.

[0030] Instead of, or in addition to, the bucket 23, it is possible to attach other work tools (hydraulic attachments) drivable by a hydraulic actuator to the tip of the arm 22. Examples of other work tools include a hydraulic breaker, a hydraulic crusher, an angle bloom, an earth auger, a pallet fork, a sweeper, a mower, a snow blower, and the like.

[0031] The swing bracket 24 swings left and right by the extension and contraction of a swing cylinder C1 provided in the machine body 2. The boom 21 swings up and down (front and back) by the extension and contraction of a boom cylinder C2. The arm 22 swings up and down (front and back) by the extension and contraction of an arm cylinder C3. The bucket 23 performs a curl operation and a dump operation by the extension and contraction of a bucket cylinder (work tool cylinder) C4. The swing cylinder C1, the boom cylinder C2, the arm cylinder C3, and the bucket cylinder C4 are composed of hydraulic cylinders.

[0032] The electric working machine 1 drives the traveling device 10 by traveling motors ML and MR, drives the working device 20 by hydraulic cylinders C1 to C5, and turns the machine body 2 by a slewing motor MT to perform operations such as excavation. Hydraulic actuators such as the traveling motors ML and MR, the slewing motor MT, and the hydraulic cylinders C1 to C5 are included in the hydraulic equipment. Not only the working device 20 but also the traveling device 10 is a working device provided in the electric working machine 1. Hereinafter, for convenience, the working device 20 and the traveling device 10 are collectively referred to as "working devices 20, 10".

[0033] Next, the electrical configuration of the electric working machine 1 will be described. FIG. 1 is an electrical block diagram of the electric working machine 1. In FIG. 1, the control device 7 has a CPU 7a and a storage unit 7b. The CPU 7a controls the operations of each part provided in the electric working machine 1 shown in FIG. 1. The storage unit 7b is composed of a volatile memory, a non-volatile memory, and the like. Information, data, programs, etc. for the CPU 7a to control the operations of each part are stored in the storage unit 7b in a readable and writable manner.

[0034] The operating device 5 has operating members such as a working operation lever 5a, a traveling operation lever 5b, an unloading lever 5c, an accelerator dial 5d, and a mode selection SW (switch) 5e. The operating device 5 also has a potentiometer, a switch, a sensor, etc. (not shown) for detecting the presence or absence of operation, the operation position, or the operation amount of each operating member 5a to 5e.

[0035] The working operation lever 5a is an operating member for operating the operation of the working device 20. The traveling operation lever 5b is a member for operating the operation of the traveling device 10. In FIG. 1, for the sake of convenience, the working operation lever 5a and the traveling operation lever 5b are each shown as one block, but in reality, a plurality of working operation levers 5a and a plurality of traveling operation levers 5b are provided respectively.

[0036] The unloading lever 5c is a member that can be switched to either a load position (first position) that permits the operation of the working device 20 or an unloading position (second position) that does not permit (prohibits) the operation of the working device 20. The unloading lever 5c is installed, for example, on the side of the driver's seat 4 (FIG. 9) so as to be swingable up and down.

[0037] By swinging the unloading lever 5c downward to position it at the load position (first position, lowered position), the passage for the operator to get on and off the cab 4R is closed. By swinging the unloading lever 5c upward to position it at the unloading position (second position), the above passage is opened.

[0038] The accelerator dial 5d is rotated to indicate the rotational speed of the electric motor 9. The angle range within which the accelerator dial 5d can be rotated corresponds to the indication range within which the rotational speed of the electric motor 9 can be indicated. Therefore, by changing the operation position of the accelerator dial 5d, the indicated value of the rotational speed of the electric motor 9 can also be changed.

[0039] The control device 7 calculates an instruction value for the rotational speed of the electric motor 9 according to the operation state (presence or absence of operation and operation position) of the accelerator dial 5d, and determines the instruction value as the target rotational speed. At this time, for example, when the control device 7 detects the operation position of the accelerator dial 5d, it may refer to a LUT (Lookup table) stored in advance in the storage unit 7b to determine an instruction value for the rotational speed of the electric motor 9 corresponding to the operation position. Alternatively, for example, the control device 7 may convert a signal output from a switch or a sensor according to the operation position of the accelerator dial 5d into a digital value (such as a voltage value or a current value), apply the digital value to an arithmetic expression stored in advance, and calculate an instruction value for the rotational speed of the electric motor 9. The accelerator dial 5d is an example of the "instruction member" of the present invention.

[0040] The mode selection SW5e is a switch operated to select either a normal mode (first mode) for controlling the drive of the electric motor 9 or an ECO mode (ecology mode, second mode) that reduces power consumption compared to the normal mode.

[0041] The starter SW (switch) 8 is provided inside the protection mechanism 6 and is operable by an operator seated in the driver's seat 4. The starter SW8 is operated to start or stop the electric working machine 1. Specifically, by turning on the starter SW8, the control device 7 starts each part provided in the electric working machine 1. Also, by turning off the starter SW8, the control device 7 stops each part provided in the electric working machine 1.

[0042] The electric motor 9 is a drive source (an example of a prime mover) of the electric working machine 1 and is composed of, for example, a permanent magnet embedded type three-phase AC synchronous motor. The inverter 38 is a motor drive device that drives the electric motor 9. The inverter 38 is connected to the electric motor 9 and the junction box 39.

[0043] The junction box 39 is connected to the battery unit 30, the DC-DC converter 40, and the charging port 41, in addition to the inverter 38. The junction box 39 outputs the power output from the battery unit 30 to the inverter 38 and the DC-DC converter 40.

[0044] The inverter 38 converts the DC power input from the battery unit 30 via the junction box 39 into three-phase AC power, and supplies the three-phase AC power to the electric motor 9. As a result, the electric motor 9 is driven. Also, the inverter 38 can arbitrarily adjust the current and voltage of the power supplied to the electric motor 9. The control device 7 controls the operation of the inverter 38 to drive or stop the electric motor 9.

[0045] The rotation speed detection device 42 is composed of a sensor, an encoder, a pulse generator, etc. that detect the rotation speed (actual rotation speed) of the electric motor 9. The control device 7 controls the driving and stopping of the electric motor 9 by controlling the driving of the inverter 38 based on, for example, the rotation speed (actual rotation speed) of the electric motor 9 detected by the rotation speed detection device 42. Also, the control device 7 controls the driving of the electric motor 9 by the inverter 38 so that the actual rotation speed of the electric motor 9 detected by the rotation speed detection device 42 matches the target rotation speed.

[0046] The DC-DC converter 40 is a voltage conversion device that converts the voltage of the DC Power input from the battery unit 30 via the junction box 39 into a different voltage. In the present embodiment, the DC-DC converter 40 is a step-down converter that converts the high voltage of the battery unit 30 into a predetermined low voltage according to the electrical components provided in the electric working machine 1. The DC-DC converter 40 supplies power to the low-voltage battery 33 after voltage conversion. The electrical components provided in the electric working machine 1 include lighting, heaters, etc., in addition to the respective parts shown in FIG. 1.

[0047] The charging port 41 has a connector (not shown) into which a charging cable (not shown) is fitted and a connection detection device 41a. The charging port 41 is connected to an external power source (such as a commercial power source) via the charging cable. The connection detection device 41a is composed of a sensor or the like that detects that the charging cable is fitted to the charging port 41 and the external power source is connected.

[0048] The junction box 39 outputs the power input from the external power source via the charging cable to the charging port 41 to the battery unit 30. The battery unit 30 is charged with the power input from the charging port 41 via the junction box 39.

[0049] The battery unit 30 has a plurality of battery packs 31, 32. Each of the battery packs 31, 32 is a secondary battery (storage battery) such as a lithium-ion battery composed of at least one battery. When each of the battery packs 31, 32 is composed of a plurality of batteries, the plurality of batteries are electrically connected in series and / or in parallel. Further, the batteries constituting each of the battery packs 31, 32 have a plurality of cells inside, and the plurality of cells are electrically connected in series and / or in parallel. Each of the battery packs 31, 32 has an electric capacity capable of operating each part of the electric working machine 1 for a predetermined time. The battery packs 31, 32 are connected in parallel with each other.

[0050] In the present embodiment, two battery packs 31, 32 are provided in the battery unit 30, but the number of battery packs included in the battery unit 30 is not limited to two, and may be one or three or more.

[0051] Each of the battery packs 31, 32 is provided with a connection switching unit 31a, 32a. Each of the connection switching units 31a, 32a is composed of, for example, a relay or a switch and can be switched between a connected state and a disconnected state.

[0052] The control device 7 controls the power output and output stop of each battery pack 31, 32 by switching one of the connection switching parts 31a, 32a to the connected state and the other connection switching part to the cut-off state, thereby outputting power from one of the plurality of battery packs 31, 32 to the junction box 39 and stopping the power output from the other battery pack. That is, the control device 7 controls the power output and output stop of each battery pack 31, 32.

[0053] In addition, the control device 7 switches the internal connection state of the junction box 39 to connect or disconnect the inverter 38, the DC-DC converter 40, or the charging port 41 to / from each battery pack 31, 32. The junction box 39 and the connection switching parts 31a, 32a are connection switching devices that switch the connection and disconnection of the inverter 38, the DC-DC converter 40, and the charging port 41 to / from each battery pack 31, 32.

[0054] Each of the battery packs 31, 32 is provided with a BMU (battery management unit) 31b, 32b. In FIG. 1, the BMUs 31b, 32b are provided in the corresponding battery packs 31, 32, but the BMUs 31b, 32b may be built in the corresponding battery packs 31, 32, or may be installed outside the battery packs 31, 32.

[0055] The BMU 31b monitors and controls the corresponding battery pack 31. The BMU 32b monitors and controls the corresponding battery pack 32. Specifically, the BMUs 31b, 32b control the opening and closing of the relays provided inside the battery packs 31, 32 to control the start and stop of the power supply from the battery packs 31, 32. In addition, the BMUs 31b, 32b detect the temperature, voltage, current, or terminal voltage of the internal cells of the battery packs 31, 32.

[0056] Furthermore, the BMU 31b and 32b detect the remaining capacity (remaining power amount) of the battery packs 31 and 32 by a voltage measurement method, for example, based on the terminal voltages of the cells inside the battery packs 31 and 32. Note that the method for detecting the remaining capacity of the battery packs 31 and 32 is not limited to the voltage measurement method, and other methods such as a Coulomb counter method, a battery cell modeling method, and an impedance track method may be used. Also, a capacity detection unit for detecting the remaining capacity of the battery packs 31 and 32 may be provided separately from the BMU 31b and 32b.

[0057] The low-voltage battery 33 is a storage battery with a voltage lower than that of the battery unit 30. The low-voltage battery 33 is charged by the power supplied from the DC-DC converter 40. The low-voltage battery 33 supplies power to the electrical components provided in the electric working machine 1.

[0058] The radiator 35 cools the cooling water for cooling high heat-generating electrical devices such as the electric motor 9, the inverter 38, the DC-DC converter 40, and the battery unit 30. The high heat-generating electrical devices are electrical devices that generate more heat than other electrical devices provided in the electric working machine 1 by operating with power. The cooling water is not simply water, but is composed of a liquid that does not freeze even in cold regions, for example.

[0059] The radiator 35 has a fan motor 35a, a radiator fan that is rotationally driven by the power of the fan motor 35a, and a heat exchange part (not shown). The fan motor 35a is driven by the power of the low-voltage battery 33.

[0060] The cooling pump 36 is provided in a cooling water passage (not shown) disposed in the machine body 2 together with the radiator 35 and the above-described high heat-generating electrical devices. The cooling pump 36 discharges and circulates the cooling water through the cooling water passage.

[0061] The oil cooler 37 cools the hydraulic oil that has passed through the hydraulic actuators ML, MR, MT, C1 to C5 described above, and hydraulic equipment such as the hydraulic pumps P1, P2 and control valve CV (shown in Fig. 2 etc.) to be described later. The oil cooler 37 has a fan motor 37a, an oil cooler fan rotationally driven by the power of the fan motor 37a, and a heat exchange section (not shown). The fan motor 37a is driven by the power of the low-voltage battery 33.

[0062] The display device 43 is composed of a liquid crystal display, a touch panel, etc., and displays various kinds of information. For example, the display device 43 displays information indicating the drive state of the electric motor 9 etc. The oil temperature detection device 44 is composed of a sensor that detects the temperature of the hydraulic oil. Hereinafter, the temperature of the hydraulic oil is referred to as "hydraulic oil temperature".

[0063] The AI (Auto Idling)-SW (Switch) 45 is composed of a pressure sensor that operates by the hydraulic pressure of the hydraulic oil. The AI-SW 45 turns on when at least one of the working devices 20, 10 is operating, and turns off when neither of the working devices 20, 10 is operating. That is, the AI-SW 45 detects the presence or absence of the operation of the working devices 20, 10.

[0064] Next, the hydraulic circuit provided in the electric working machine 1 will be described. Fig. 2 is a diagram showing the hydraulic circuit K provided in the electric working machine 1. The hydraulic circuit K is provided with hydraulic equipment such as hydraulic actuators C1 to C5, ML, MR, MT, control valve CV, hydraulic pumps P1, P2, hydraulic oil tank 48, oil cooler 37, operation valves PV1 to PV6, unloading valve 58, and oil passage 50.

[0065] Among the plurality of provided hydraulic pumps P1, P2, one is the working hydraulic pump P1 and the other is the control hydraulic pump P2. These hydraulic pumps P1, P2 are driven by the power of the electric motor 9.

[0066] The working hydraulic pump P1 sucks the hydraulic oil stored in the hydraulic oil tank 48 and then discharges the hydraulic oil toward the control valve CV. In FIG. 2, for the sake of convenience, one working hydraulic pump P1 is illustrated, but it is not limited thereto, and an appropriate number of working hydraulic pumps P1 may be provided so as to supply hydraulic oil to each of the hydraulic actuators C1 to C5, ML, MR, and MT.

[0067] The control hydraulic pump P2 sucks the hydraulic oil stored in the hydraulic oil tank 48 and then discharges it, thereby outputting hydraulic pressure for signals or control. That is, the control hydraulic pump P2 supplies (discharges) pilot oil. An appropriate number of control hydraulic pumps P2 may also be provided as needed.

[0068] The control valve CV has a plurality of control valves V1 to V8. Each of the control valves V1 to V8 controls the flow rate of the hydraulic oil output from the hydraulic pumps P1 and P2 to each of the hydraulic actuators C1 to C5, ML, MR, and MT to Control (adjustment ) do .

[0069] Specifically, the swing control valve V1 controls the flow rate of the hydraulic oil supplied to the swing cylinder C1. The boom control valve V2 controls the flow rate of the hydraulic oil supplied to the boom cylinder C2. The arm control valve V3 controls the flow rate of the hydraulic oil supplied to the arm cylinder C3. The bucket control valve V4 controls the flow rate of the hydraulic oil supplied to the bucket cylinder C4. The dozer control valve V5 controls the flow rate of the hydraulic oil supplied to the dozer cylinder C5. The left travel control valve V6 controls the flow rate of the hydraulic oil supplied to the left travel motor ML. The right travel control valve V7 controls the flow rate of the hydraulic oil supplied to the right travel motor MR. The swing control valve V8 controls the flow rate of the hydraulic oil supplied to the swing motor MT.

[0070] The operation valves (remote control valves) PV1 to PV6 operate in response to the operation of the operation levers 5a and 5b (Fig. 1) provided in the operation device 5. Pilot oil acts on each control valve V1 to V8 in proportion to the operating amount (operation amount) of each operation valve PV1 to PV6, causing the spool of each control valve V1 to V8 to move linearly. Then, hydraulic oil with a flow rate proportional to the movement amount of the spool of each control valve V1 to V8 is supplied to the hydraulic actuators C1 to C5, ML, MR, and MT to be controlled. Further, each hydraulic actuator C1 to C5, ML, MR, and MT is driven according to the supply amount of the hydraulic oil from each control valve V1 to V8.

[0071] In other words, when the operation levers 5a and 5b are operated, the hydraulic oil (pilot oil) acting on the control valves V1 to V8 is adjusted, and the control valves V1 to V8 are controlled. Then, the flow rate of the hydraulic oil supplied from the control valves V1 to V8 to the hydraulic actuators C1 to C5, ML, MR, and MT is adjusted, and the driving and stopping of the hydraulic actuators C1 to C5, ML, MR, and MT are controlled.

[0072] The oil passage 50 is composed of, for example, a pipe formed of a material such as a hose or metal. The oil passage 50 connects each part provided in the hydraulic circuit K and is a flow path through which hydraulic oil or pilot oil flows to each part. The oil passage 50 includes a first oil passage 51, a second oil passage 52, a first suction oil passage 54, a second suction oil passage 55, and a restriction oil passage 57.

[0073] The first suction oil passage 54 is a flow path through which the hydraulic oil sucked by the hydraulic pump P1 for operation from the hydraulic oil tank 48 flows. The second suction oil passage 55 is a flow path through which the hydraulic oil sucked by the hydraulic pump P2 for control from the hydraulic oil tank 48 flows. The first oil passage 51 is a flow path through which the hydraulic oil discharged by the hydraulic pump P1 for operation flows toward the control valves V1 to V8 of the control valve CV. The first oil passage 51 branches into a plurality within the control valve CV and is connected to each control valve V1 to V8. The second oil passage 52 is a flow path through which the hydraulic oil that has passed through the control valves V1 to V8 flows toward the hydraulic oil tank 48. The hydraulic oil tank 48 stores the hydraulic oil. The second oil passage 52 includes a reciprocating oil passage 52a and a discharge oil passage 52b.

[0074] A plurality of reciprocating oil passages 52a are provided in pairs of two, connecting each of the control valves V1 to V8 and the hydraulic actuators C1 to C5, ML, MR, MT to be controlled. The reciprocating oil passage 52a is a flow path that supplies hydraulic oil from the connected control valves V1 to V8 to the hydraulic actuators C1 to C5, ML, MR, MT, or returns the hydraulic oil from the hydraulic actuators C1 to C5, ML, MR, MT to the control valves V1 to V8. One end side of the discharge oil passage 52b branches into a plurality and is connected to each of the control valves V1 to V8. The other end of the discharge oil passage 52b is connected to the hydraulic oil tank 48.

[0075] A part of the hydraulic oil flowing through any one of the control valves V1 to V8 through the first oil passage 51 passes through the control valve V1 to V8, passes through one of the reciprocating oil passages 52a, and is supplied to the hydraulic actuators C1 to C5, ML, MR, MT to be controlled. Then, the hydraulic oil discharged from the hydraulic actuators C1 to C5, ML, MR, MT returns to the connected control valves V1 to V8 through the other of the reciprocating oil passages 52a, passes through the control valves V1 to V8, and flows into the discharge oil passage 52b.

[0076] The other part of the hydraulic oil flowing through any one of the control valves V1 to V8 through the first oil passage 51 flows into the discharge oil passage 52b through the control valve V1 to V8 without being supplied to the hydraulic actuators C1 to C5, ML, MR, MT. An oil cooler 37 is provided in the discharge oil passage 52b. The oil cooler 37 cools the hydraulic oil flowing through the discharge oil passage 52b from any one of the control valves V1 to V8.

[0077] The hydraulic oil cooled by the oil cooler 37 returns to the hydraulic oil tank 48 through the discharge oil passage 52b. As described above, the oil passages 54, 51, 52 are arranged to circulate the hydraulic oil with respect to the hydraulic oil tank 48, the hydraulic pump P1, the control valves V1 to V8 of the control valve CV, and (a part of the hydraulic oil also includes the hydraulic actuators C1 to C5, ML, MR, MT).

[0078] The restriction oil passage 57 is a passage that allows the hydraulic oil discharged by the control hydraulic pump P2 to flow to the operation valves PV1 to PV6. One end of the restriction oil passage 57 is connected to the control hydraulic pump P2, and the other end branches into a plurality of parts and is connected to the primary ports of the respective operation valves PV1 to PV6 (primary ports).

[0079] An unloading valve 58 composed of a two-position switching solenoid valve is provided in the restriction oil passage 57. The unloading valve 58 switches to either the first position 58a or the second position 58b in conjunction with the operation of the unloading lever 5c (FIG. 1). When the unloading valve 58 switches to the first position 58a, hydraulic oil is supplied from the hydraulic pump P1 for operation to the hydraulic actuators C1 to C5, ML, MR, and MT, and the operation of the hydraulic actuators C1 to C5, ML, MR, MT, the working device 20, and the traveling device 10 is permitted. Also, when the unloading valve 58 switches to the second position 58b, the supply of hydraulic oil from the hydraulic pump P1 for operation to the hydraulic actuators C1 to C5, ML, MR, and MT is blocked, and the operation of the hydraulic actuators C1 to C5, ML, MR, MT, the working device 20, and the traveling device 10 is not permitted (operation prohibited state).

[0080] Specifically, when the unloading lever 5c is operated to the load position (first position), the unloading valve 58 is switched by the control device 7 to the first position (oil supply position, load position) 58a, and the hydraulic oil discharged from the control hydraulic pump P2 to the restriction oil passage 57 is supplied to the operation valves PV1 to PV6, enabling the control valves V1 to V8 to be operated. As a result, the hydraulic actuators C1 to C5, ML, MR, MT, the working device 20, and the traveling device 10 can also be operated, and the operation of these respective parts C1 to C5, ML, MR, MT, 20, and 10 is permitted. The hydraulic oil discharged from the operation valves PV1 to PV6 returns to the hydraulic oil tank 48 through another discharge oil passage (not shown).

[0081] Also, when the unloading lever 5c is operated to the unloading position (second position), the unloading valve 58 is switched by the control device 7 to the second position (oil cutoff position, unloading position) 58b, and the hydraulic oil discharged from the control hydraulic pump P2 to the restriction oil passage 57 is no longer supplied to the operation valves PV1 to PV6, and the control valves V1 to V8 become inoperable (operation prohibited state). As a result, the hydraulic actuators C1 to C5, ML, MR, MT, the working device 20, and the traveling device 10 also become inoperable, and the operations of these respective parts C1 to C5, ML, MR, MT, 20, 10 are not permitted. Further, the unloading valve 58 may be switched to the first position or the second position by the control device 7 regardless of the operation position of the unloading lever 5c.

[0082] In addition to the above, the hydraulic circuit K is provided with an operation detection oil passage (not shown) for detecting the operation states of the control valves V1 to V8. The operation detection oil passage is an oil passage that returns the pilot oil discharged from the control hydraulic pump P2 to the hydraulic oil tank 48 through a plurality of switching valves for switching the positions of the control valves V1 to V8 in sequence. In the operation detection oil passage, an AI-SW45 (FIG. 1) is connected to the upstream side of the control valve V1 disposed closest to the control hydraulic pump P2 side.

[0083] When any one of the control valves V1 to V8 is operated from the neutral position to the switching position, a part of the operation detection oil passage is blocked, and the pressure of the pilot oil in the operation detection oil passage becomes somewhat high (a so-called pressurized state), and the AI-SW45 is turned on. That is, it is detected by the AI-SW45 that at least one of the working devices 20, 10 is operating. Also, when all of the control valves V1 to V8 are in the neutral position, since the operation detection oil passage is open, the pressure of the pilot oil in the operation detection oil passage does not become high to a certain extent (a so-called non-pressurized state), and the AI-SW45 is turned off. That is, it is detected by the AI-SW45 that the working devices 20, 10 are not operating.

[0084] Next, the operation of the electric working machine 1 will be described. FIG. 3A is a diagram showing, in a table, an example of the basic control data Lab of the rotational speed of the electric motor 9. FIG. 3B is a diagram showing, in a graph, an example of the basic control data Lab of the rotational speed of the electric motor 9. FIG. 4 is a diagram showing, in a graph, an example of the basic control data Lab and the control data La of the rotational speed of the electric motor 9. FIG. 5 is a flowchart showing an example of the control operation of the rotational speed of the electric motor 9 in the electric working machine 1.

[0085] The basic control data Lab shown in FIGS. 3A to 4 is pre-stored in the storage unit 7b of the control device 7. The storage unit 7b is an example of the "storage device" of the present invention. The series of control operations shown in FIG. 5 are executed by the CPU 7a of the control device 7 based on the software program pre-stored in the storage unit 7b and the basic control data Lab. Hereinafter, for convenience, the rotational speed of the electric motor 9 will be referred to as the "motor rotational speed".

[0086] The basic control data Lab shown in FIGS. 3A and 3B, etc., is control data showing the change in the motor rotational speed for gradually increasing the motor rotational speed from 0 rpm to a predetermined basic target rotational speed (2200 rpm) Rtb with a predetermined basic delay time (25 seconds) Zab when starting the electric motor 9 when the operating oil temperature is at or below a predetermined temperature (for example, -10°C). Also, FIGS. 3A and 3B show the correlation between the elapsed time since starting to increase the motor rotational speed and the control value of the motor rotational speed. Also, as shown in FIG. 3B, the basic control data Lab is curved data.

[0087] The basic target rotational speed (2200 rpm) Rtb is the maximum rotational speed that can be set for the electric motor 9. The basic delay time (25 seconds) Zab is the time from starting to increase the motor rotational speed until it is set to the basic target rotational speed Rtb. For example, in another working machine equipped with a diesel engine as a prime mover, the basic control data Lab is created so as to match the measured data showing the change in the rotational speed of the diesel engine when starting the diesel engine in a situation where the operating oil temperature is at or below a predetermined temperature.

[0088] As shown in FIG. 3B, in the basic control data Lab, the basic delay time (25 seconds) Zab is divided into three parts: a predetermined immediately-after-start interval Zab1, an intermediate interval Zab2, and an immediately-before-end interval Zab3. Among them, in the intermediate interval Zab2, it increases (substantially proportionally) in proportion to the elapsed time from the start point t0 of the increase in the motor rotation speed. Also, in the immediately-after-start interval Zab1 and the immediately-before-end interval Zab3 corresponding to the time before and after the intermediate interval Zab2, the motor rotation speed increases more gently than in the intermediate interval Zab2 Zab2. Further, the motor rotation speed reaches the basic target rotation speed Rtb (maximum rotation speed 2200 rpm) in "24 seconds" after starting to increase. However, in order to stabilize the motor rotation speed at the basic target rotation speed Rtb, the basic delay time Zab is set to "25 seconds", which is longer than "24 seconds". That is, the basic delay time Zab is set to a time that enables the electric motor 9 to start and stabilize the motor rotation speed at the basic target rotation speed Rtb.

[0089] For example, when the starter SW8 (FIG. 1) is turned on by the operator, the control device 7 determines that there is a start instruction for the electric motor 9 (S1 in FIG. 5) and determines the target rotation speed Rt of the electric motor 9 according to the operation position of the accelerator dial 5d (FIG. 1) (S2). Also, the control device 7 detects the operating oil temperature by the oil temperature detection device 44. When the operating oil temperature is higher than a predetermined temperature (for example, a low temperature such as -10°C) (S3: NO), the inverter 38 supplies power to the electric motor 9 to start the electric motor 9 and immediately increases the motor rotation speed to set it to the target rotation speed Rt (S4). Thereby, the start of the electric motor 9 is completed and the electric motor 9 enters the driving state. After that, the control device 7 waits for an instruction to change the motor rotation speed while holding the motor rotation speed at the target rotation speed Rt.

[0090] On the one hand, when the operating oil temperature is equal to or lower than a predetermined temperature (S3: YES), the control device 7 determines a delay time Za until the motor rotation speed is set to the target rotation speed Rt based on the basic control data Lab stored in the storage unit 7b and the target rotation speed Rt (S5). Further, the control device 7 creates control data La indicating a change in the motor rotation speed for setting the motor rotation speed to the target rotation speed Rt with the delay time Za applied (S6).

[0091] For example, when the target rotation speed Rt is equal to the basic target rotation speed Rtb, the control device 7 determines the basic delay time Zab (such as in FIG. 3B) as the delay time Za (S5 in FIG. 5), and creates (determines) the basic control data Lab as the control data La (S6).

[0092] On the contrary, when the target rotation speed Rt is different from the basic target rotation speed Rtb, that is, when the target rotation speed Rt is lower than the basic target rotation speed Rtb, the control device 7 determines the delay time Za based on, for example, the difference between the basic target rotation speed Rtb and the target rotation speed Rt and the basic control data Lab (S5), and creates the control data La (S6).

[0093] Specifically, for example, when the control device 7 determines the target rotation speed Rt to be "1000 rpm" according to the operation position of the accelerator dial 5d, assuming the case where the rotation speed of the electric motor 9 is changed based on the basic control data Lab shown in FIGS. 3A to 4, the elapsed time "11 seconds" until the motor rotation speed reaches "1000 rpm" is determined as the delay time Za (S5 in FIG. 5).

[0094] Further, the control device 7 creates the control data La by reducing and correcting the basic control data Lab according to the difference between the basic target rotation speed (2200 rpm) Rtb and the target rotation speed (1000 rpm) Rt and the delay time (11 seconds) Za (S6 in FIG. 5). More specifically, as shown in FIG. 4 and the like, the basic control data Lab is such that the elapsed time is the basic delay time Zab and includes a basic end point Qeb at which the rotation speed of the electric motor 9 is the basic target rotation speed Rtb. The control device 7 creates control data La by reducing and correcting the basic control data Lab so that the basic end point Qeb coincides with a target end point Qe at which the elapsed time is the delay time Za and the rotation speed of the electric motor 9 is the target rotation speed Rt. Even when another target rotation speed Rt is determined according to the operation position of the accelerator dial 5d, the delay time Za is determined and the control data La is created in the same manner as described above.

[0095] As shown in FIG. 4, also in the control data La, the delay time Za is divided into three: a predetermined immediately-after-start section Za1, a middle section Za2, and an immediately-before-end section Za3. In the middle section Za2, the motor rotation speed increases in proportion to the elapsed time from the start time point t0 of the increase. Also, in the immediately-after-start section Za1 and the immediately-before-end section Za3, the rotation speed of the electric motor 9 also increases more gently than in the middle section Za2. Further, the motor rotation speed reaches the target rotation speed Rt in about "10.5 seconds" after starting to increase. However, in order to stabilize the motor rotation speed at the target rotation speed Rt, the delay time Za is set to "11 seconds", which is longer than "10.5 seconds". That is, the delay time Za is set to a time that enables starting the electric motor 9 and stabilizing the motor rotation speed at the target rotation speed Rt.

[0096] Next, the control device 7 adjusts the magnitude of the power (for example, current) supplied to the electric motor 9 by the inverter 38 according to the control data La, and gradually increases the motor rotation speed over the delay time Za to set it to the target rotation speed Rt (S7 in FIG. 5). At this time, the control device 7 counts the elapsed time since starting to increase the motor rotation speed, compares the actual rotation speed of the electric motor 9 detected by the rotation speed detection device 42 with the control value of the motor rotation speed indicated by the control data La at a predetermined timing, and controls the motor rotation speed by the inverter 38 so that the actual rotation speed approaches the control value. At this time, the control device 7 may also control the motor rotation speed by the inverter 38 so that the actual rotation speed of the electric motor 9 becomes equal to or lower than the control value.

[0097] Each point shown on the control data La and Lab in FIGS. 3B and 4 is a predetermined timing at which the control device 7 compares the actual rotational speed of the electric motor 9 with the control value of the motor rotational speed. In the immediately-started intervals Za1 and Zab1 and the immediately-before-ending intervals Za3 and Zab3 at the delay times Za and Zab, the comparison timings are more numerous and the intervals between the comparison timings are shorter than in the intermediate intervals Za2 and Zab2. That is, the control device 7 compares the actual rotational speed of the electric motor 9 with the control value of the motor rotational speed more times in the immediately-started intervals Za1 and Zab1 and the immediately-before-ending intervals Za3 and Zab3 than in the intermediate intervals Za2 and Zab2.

[0098] When the motor rotational speed is set to the target rotational speed Rt after applying the delay time Za (S7 in FIG. 5), the start of the electric motor 9 is completed and the electric motor 9 enters the driving state. After that, the control device 7 waits for an instruction to change the motor rotational speed while holding the motor rotational speed at the target rotational speed Rt.

[0099] During the driving of the electric motor 9, for example, when the accelerator dial 5d is operated by the operator, the control device 7 determines that there is an instruction to change the motor rotational speed (S8: YES in FIG. 5) and calculates the target rotational speed Rt according to the operation position of the accelerator dial 5d (S9). Then, the control device 7 adjusts the power supplied to the electric motor 9 by the inverter 38 to change the motor rotational speed to match the target rotational speed Rt (S10).

[0100] After that, if there is no instruction to stop the electric motor 9 (S11: NO), the control device 7 proceeds to process S8 and waits again for an instruction to change the motor rotational speed. Also, for example, when the starter SW8 is turned off by the operator, the control device 7 determines that there is an instruction to stop the electric motor 9 (S11: YES) and cuts off the power supply to the electric motor 9 by the inverter 38 to stop the electric motor 9 (S12).

[0101] In the embodiment shown in FIG. 5, when the operating oil temperature is equal to or lower than a predetermined temperature, an example is shown in which when starting the electric motor 9, the motor speed is gradually increased with a delay time Za and set to the target speed Rt. However, the present invention is not limited to this example. For example, when the electric motor 9 is being driven and the operating oil temperature is equal to or lower than a predetermined temperature, when changing the motor speed to a higher speed by operating the accelerator dial 5d, the control device 7 may also calculate the target speed according to the operation position of the accelerator dial 5d, determine the delay time, and create control data indicating the change in the motor speed. Then, the control device 7 may gradually increase the motor speed according to the control data and set it to the target speed.

[0102] Also, during the execution of process S7 in FIG. 5, that is, during the gradual increase in the motor speed, the operator may be notified that it takes time (delay time Za) to start the electric motor 9, or the operation of the accelerator dial 5d may be accepted to change the target speed Rt. These embodiments are shown in FIG. 6.

[0103] FIG. 6 is a flowchart showing an example of the details of process S7 in FIG. 5. After passing through processes S1 to S3, S5, and S6 in FIG. 5, the control device 7 starts to gradually increase the motor speed by the inverter 38 according to the control data La in process S7 (S21 in FIG. 6), and then causes the display device 43 to display a notification (motor starting notification) indicating that the electric motor 9 is starting (S22). As the motor starting notification, for example, a message such as "Motor starting" or "Motor output limited" is displayed on the display device 43 by the control device 7. Alternatively, the control device 7 may cause the display device 43 to display the delay time Za and the elapsed time since the start of the gradual increase in the motor speed, or may cause the display device 43 to display the ratio (%) of the elapsed time to the delay time Za.

[0104] And if there is no instruction to change the motor speed (S23: NO), the delay time Za has not elapsed, or the actual speed of the electric motor 9 detected by the speed detector 42 has not reached the target speed Rt (S24: NO), the control device 7 checks whether the elapsed time since the gradual increase in the motor speed started has exceeded the immediately - after - start period Za1.

[0105] If the elapsed time has not exceeded the immediately - after - start period Za1 (S25: NO, elapsed time < immediately - after - start period Za1), the control device 7 prohibits the operation of the working devices 20, 10 by switching the unloading valve 58 (Fig. 2) to the second position 58b (S26 in Fig. 6). Thereby, even if the operator operates the operation members 5a, 5b (Fig. 1), the operation is not accepted, and the working devices 20, 10 do not operate. On the contrary, if the elapsed time has exceeded the immediately - after - start period Za1 (S25: YES, elapsed time ≥ immediately - after - start period Za1), the control device 7 permits the operation of the working devices 20, 10 by switching the unloading valve 58 to the first position 58a (S27). Thereby, when the operator operates either of the operation members 5a, 5b, the operation is accepted, and the working devices 20, 10 operate according to the operation.

[0106] On the other hand, during the gradual increase in the motor speed, if, for example, the operator operates the accelerator dial 5d, the control device 7 determines that there is an instruction to change the motor speed (S23: YES), and determines a new target speed Rt according to the operation position of the accelerator dial 5d (S28). And if the new target speed Rt is greater than or equal to the actual speed of the electric motor 9 detected by the speed detector 42 at this time (S29: NO), the control device 7 discards the new target speed Rt and continues the gradual increase in the motor speed according to the control data La (S30). That is, the target speed Rt calculated in process S2 in Fig. 5, the delay time Za determined in process S5, and the control data La created in process S6 are respectively held, and the gradual increase in the motor speed is continued according to the control data La.

[0107] On the other hand, if the new target rotation speed Rt is less than the actual rotation speed of the electric motor 9 (S29: YES), the control device 7 temporarily interrupts the gradual increase in the motor rotation speed during execution (S31). Then, the control device 7 changes the delay time Za according to the new target rotation speed Rt (S32), and changes the control data La according to the new target rotation speed Rt and the changed delay time Za (S33). At this time, the changed delay time Za is shorter than the delay time Za before the change. Also, the control data La is changed only for the section from the time (S31) when the gradual increase in the motor rotation speed is interrupted to the end time of the changed delay time Za. Then, the control device 7 resumes the gradual increase in the motor rotation speed according to the changed control data La (S34).

[0108] Thereafter, when there is no instruction to change the motor rotation speed (S23: NO), the delay time Za has elapsed, and the actual rotation speed of the electric motor 9 reaches the target rotation speed Rt (S24: YES), the control device 7 stops the gradual increase in the motor rotation speed by the inverter 38 and holds the motor rotation speed at the target rotation speed Rt (S35). As a result, the start of the electric motor 9 is completed and the electric motor 9 enters the driving state. Also, the control device 7 stops (turns OFF) the display of the motor start notification by the display device 43 (S36). After this, the control device 7 shifts to the process S8 in FIG. 5 while holding the motor rotation speed at the target rotation speed Rt, and waits for an instruction to change the motor rotation speed.

[0109] As another example, instead of the process S24 in FIG. 6, only one of the conditions that the delay time Za has elapsed and that the actual rotation speed of the electric motor 9 has reached the target rotation speed Rt is adopted. If the adopted condition is not satisfied, the determination S25 is executed, and if the adopted condition is satisfied, the process S35 may be executed.

[0110] The numerical values such as the predetermined temperature, delay times Za and Zab, target rotation speeds Rt and Rtb, and the elapsed time and motor rotation speed of the control data La and Lab shown in the above embodiments are merely examples and are not limited to these values. Also, the number and interval of the timing for comparing the control values of the control data La and Lab shown in FIG. 4 etc. with the actual rotation speed of the electric motor 9 may be reduced as the delay time Za is shortened.

[0111] In the above embodiments, an example is shown in which the control device 7 starts and stops the electric motor 9 in response to the on / off operation of the starter SW8, and calculates the target rotation speed Rt of the electric motor 9 in response to the operation of the accelerator dial 5d. However, the present invention is not limited to this. For example, the control device 7 may start and stop the electric motor 9 or set the target rotation speed of the electric motor 9 in response to a command from a remote operation device. Alternatively, the target rotation speed at the start of the electric motor 9 may be set to a preset rotation speed.

[0112] In the above embodiments, an example is shown in which the basic target rotation speed Rtb and the basic delay time Zab of the basic control data Lab are set to their maximum values respectively. However, the present invention is not limited to this. A predetermined rotation speed smaller than the maximum rotation speed at which the electric motor 9 can rotate may be set as the basic target rotation speed Rtb, or a predetermined time shorter than the maximum time within the range in which the delay time Za can be set may be set as the delay time Za. Further, in these cases, the basic control data Lab may be corrected by reduction or expansion according to the difference between the basic target rotation speed Rtb and the target rotation speed Rt to create the control data La.

[0113] In the above embodiment, only one piece of basic control data Lab is shown. However, for example, the temperature range below a predetermined temperature (-10°C) is divided into a plurality of temperature ranges, and the basic control data corresponding to each temperature range is preset and stored in the storage unit 7b in advance. The control device 7 may adopt the basic control data corresponding to the temperature range to which the operating oil temperature belongs. Also, in this case, for example, a plurality of basic control data may be preset so that the basic delay time becomes longer in a temperature range lower than a higher temperature range. Further, the basic control data may be stored in advance in a storage device other than the storage unit 7b included in the control device 7.

[0114] Also, for example, a plurality of target rotation speeds of the electric motor 9 that can be instructed by operating the accelerator dial 5d may be provided in multiple steps, and a plurality of control data may be stored in the storage unit 7b in advance so as to correspond to each of the multiple-step target rotation speeds. An embodiment in this case will be described with reference to FIGS. 7 and 8.

[0115] FIG. 7 is a diagram showing an example of the accelerator dial 5d. FIG. 8 is a diagram showing an example of a plurality of control data corresponding to a plurality of target rotation speeds of the electric motor 9. The accelerator dial 5d shown in FIG. 7 can be rotationally operated to any of a low-speed position Pol, a medium-speed position Pom, and a high-speed position Poh. By rotationally operating the accelerator dial 5d and aligning the mark portion 5dm with the low-speed position Pol, the medium-speed position Pom, and the high-speed position Poh respectively, a low target rotation speed Rtl, a medium target rotation speed Rtm, and a high target rotation speed Rth can be respectively instructed as the target rotation speed Rt of the electric motor 9. Among the multiple-step target rotation speeds Rtl, Rtm, and Rth, the low target rotation speed Rtl is the smallest rotation speed, and the high target rotation speed Rth is the largest rotation speed.

[0116] The low control data Lal shown in FIG. 8 is control data indicating a change in the rotational speed of the electric motor 9 for setting the rotational speed of the electric motor 9 to the corresponding low target rotational speed Rtl by multiplying by the low delay time Zal. The medium control data Lam is control data indicating a change in the rotational speed of the electric motor 9 for setting the rotational speed of the electric motor 9 to the corresponding medium target rotational speed Rtm by multiplying by the medium delay time Zam. The high control data Lah is control data indicating a change in the rotational speed of the electric motor 9 for setting the rotational speed of the electric motor 9 to the corresponding high target rotational speed Rth by multiplying by the high delay time Zah. That is, the low target rotational speed Rtl, the low delay time Zal, and the low control data Lal correspond to each other. Also, the medium target rotational speed Rtm, the medium delay time Zam, and the medium control data Lam correspond to each other. Further, High target rotational speed Rth , the high delay time Zah and the high control data Lah correspond to each other. Among the multi-stage delay times Zal, Zam, Zah, the low delay time Zal is the shortest time, and the high delay time Lah is the longest time.

[0117] In the storage unit 7b of the control device 7, the corresponding delay times Zal, Zam, Zah and control data Lal, Lam, Lah are stored in advance for each of the multi-stage target rotational speeds Rtl, Rtm, Rth. When starting the electric motor 9 in a state where the operating oil temperature is equal to or lower than a predetermined temperature, the control device 7 reads out any of the delay times Zal, Zam, Zah and control data Lal, Lam, Lah corresponding to any of the target rotational speeds Rtl, Rtm, Rth indicated by the accelerator dial 5d from the storage unit 7b, and controls the rotational speed of the electric motor 9 based on the delay time and the control data.

[0118] In the above description, an example was shown in which three levels of target rotation speeds that can be indicated by the accelerator dial 5d were provided, and the delay time and control data were also provided in three levels corresponding thereto. However, the target rotation speed, the delay time, and the control data may be provided in two levels or four levels or more. Further, the number of target rotation speeds that can be indicated by the accelerator dial 5d may be made different from the number of the delay time and the control data. For example, assuming that the number of levels of the target rotation speed that can be indicated by the accelerator dial 5d is N, and the number of the delay time and the control data is M which is less than N, the control device 7 determines which of the following ranges the target rotation speed indicated by the accelerator dial 5d belongs to according to the magnitude of the target rotation speed, and determines the delay time and the control data corresponding to the belonging level. N steps It may be determined which range the target rotation speed belongs to, and the delay time and the control data corresponding to the belonging level may be determined.

[0119] In the above embodiment, an example in which the accelerator dial 5d is used as the indicating member and the working operation lever 5a and the traveling operation lever 5b are used as the working operation members is shown, but the present invention is not limited thereto. For example, various operation members such as push buttons, slide switches, tumbler switches, levers, joysticks, dials, or keys may be used as the working operation members and the indicating members.

[0120] The electric working machine 1 of the present embodiment has the following configuration and exhibits the following effects.

[0121] The electric working machine 1 of this embodiment includes a battery unit 30, an electric motor 9, an inverter 38 that supplies the power of the battery unit 30 to the electric motor 9 to drive the electric motor 9, hydraulic pumps P1 and P2 that are operated by the power of the electric motor 9, hydraulic devices (hydraulic motors ML, MR, MT, hydraulic cylinders C1 to C5, control valve CV) that are operated by the hydraulic pressure of the hydraulic oil discharged from the hydraulic pumps P1 and P2, an oil temperature detection device 44 that detects the temperature T of the hydraulic oil, a rotation speed detection device 42 that detects the rotation speed of the electric motor 9, and a control device 7 that controls the driving of the inverter 38 and the electric motor 9. When starting the electric motor 9 in a state where the temperature of the hydraulic oil detected by the oil temperature detection device 44 is equal to or lower than a predetermined temperature, the control device 7 gradually increases the rotation speed of the electric motor 9 to set it to the target rotation speed Rt so that the time until the rotation speed of the electric motor 9 reaches the target rotation speed Rt is longer than when starting the electric motor 9 in a state where the temperature of the hydraulic oil is higher than the predetermined temperature.

[0122] According to the above configuration, when starting the electric motor 9 in a low temperature state where the temperature of the hydraulic oil is equal to or lower than a predetermined temperature, the rotation speed of the electric motor 9 gradually increases without increasing suddenly to the target rotation speed Rt. That is, when starting the electric motor 9 in a state where the operating oil temperature is low, the time (delay time Za) from the start of starting to the completion of starting of the electric motor 9 is intentionally delayed. For this reason, the hydraulic pumps P1 and P2 do not operate suddenly, the suction negative pressure does not increase, and the occurrence of cavitation in the hydraulic oil in the hydraulic pumps P1 and P2 can be suppressed. As a result, wear and shortening of the service life of the hydraulic pumps P1 and P2 due to cavitation can be prevented.

[0123] In this embodiment, the electric working machine 1 includes an instruction member (accelerator dial) 5d that is operated to instruct the rotational speed of the electric motor 9. When starting the electric motor 9 in a state where the temperature of the hydraulic oil is equal to or lower than a predetermined temperature, the control device 7 sets the rotational speed instructed by the instruction member 5d as the target rotational speed Rt, determines a delay time Za until the rotational speed of the electric motor 9 stabilizes at the target rotational speed Rt, and gradually increases the rotational speed of the electric motor 9 after starting to increase the rotational speed of the electric motor 9 so that the rotational speed of the electric motor 9 stabilizes at the target rotational speed Rt after the elapse of the delay time Za. Thereby, when starting the electric motor 9 in a state where the temperature of the hydraulic oil is low and setting the rotational speed of the electric motor 9 to the target rotational speed Rt corresponding to the operation position of the instruction member 5d, the delay time Za and the control data La are set according to the target rotational speed Rt, and the rotational speed of the electric motor 9 can be appropriately increased gradually, and the occurrence of cavitation can be suppressed.

[0124] Also, in this embodiment, the control device 7 calculates the target rotational speed Rt according to the operation position of the instruction member 5d. Thereby, the operator can operate the instruction member 5d to arbitrarily set the target rotational speed Rt at the start of the electric motor 9. Also, even when the temperature of the hydraulic oil is in a low temperature state, when starting the electric motor 9, the rotational speed of the electric motor 9 can be set to the target rotational speed Rt desired by the operator while suppressing the occurrence of cavitation.

[0125] Also, in this embodiment, the electric working machine 1 includes a storage device (storage unit) 7b in which basic control data Lab indicating a change in the rotational speed of the electric motor 9 for stabilizing the rotational speed of the electric motor 9 at a predetermined basic target rotational speed Rtb with a predetermined basic delay time Zab is stored in advance. When changing the rotational speed of the electric motor 9 based on the basic control data Lab, the control device 7 determines the time until the rotational speed of the electric motor 9 reaches the target rotational speed Rt as the delay time Za. Thereby, taking the basic delay time Zab, the basic target rotational speed Rtb, and the basic control data Lab as a model, the delay time Za adapted to the target rotational speed Rt corresponding to the operation position of the instruction member 5d can be easily set.

[0126] Further, in the present embodiment, the basic control data Lab is curvilinear data showing the correlation between the elapsed time from the start time t0 of the increase in the rotational speed of the electric motor 9 and the rotational speed of the electric motor 9, and the elapsed time is the basic delay time Zab and includes a basic end point Qeb at which the elapsed time is the basic delay time Zab and the rotational speed of the electric motor 9 is the basic target rotational speed Rtb. The control device 7 corrects the basic control data Lab so that the basic end point Qeb coincides with the target end point Qe at which the elapsed time is the delay time Za and the rotational speed of the electric motor 9 is the target rotational speed Rt, thereby creating control data La indicating the change in the rotational speed of the electric motor 9 to stabilize the rotational speed of the electric motor 9 at the target rotational speed Rt by applying the delay time Za, and controls the rotational speed of the electric motor 9 based on the control data La. Thereby, based on the basic control data Lab and the target rotational speed Rt, the delay time Za is determined and the control data La is created. Thereby, using the basic control data Lab as a model, the control data La for setting the rotational speed of the electric motor 9 to the target rotational speed Rt by applying the delay time Za can be easily set, and the rotational speed of the electric motor 9 can be appropriately increased gradually based on the control data La.

[0127] Further, in the present embodiment, the basic target rotational speed Rtb is set to a predetermined maximum rotational speed that can be set for the electric motor 9, and the control device 7 creates the control data La by reducing and correcting the basic control data Lab so that the basic end point Qeb coincides with the target end point Qe. Thereby, using the basic control data Lab as a maximum model, the control data La corresponding to the delay time Za and the target rotational speed Rt can be easily set.

[0128] Further, in the present embodiment, the instruction member 5d can instruct a plurality of predetermined levels of target rotational speeds Rtl, Rtm, Rth, The electric working machine 1 isFor each of the multi-stage target rotation speeds Rtl, Rtm, and Rth, there is a corresponding delay time Zal, Za, Zah, and control data Lal, Lam, Lah indicating the change in the rotation speed of the electric motor 9 for stabilizing the rotation speed of the electric motor 9 at the corresponding target rotation speeds Rtl, Rtm, and Rth by multiplying the corresponding delay times Zal, Za, Zah. A storage device 7b stores these in advance. The control device 7 controls the rotation speed of the electric motor 9 based on the control data Lal, Lam, Lah corresponding to any one of the target rotation speeds Rtl, Rtm, and Rth indicated by the instruction member 5d. Thereby, when starting the electric motor 9 with the temperature of the hydraulic oil in a low temperature state and setting the rotation speed of the electric motor 9 to any one of the target rotation speeds Rtl, Rtm, and Rth corresponding to the operation position of the instruction member 5d, the control data Lal, Lam, Lah corresponding to the target rotation speed is used to gradually increase the rotation speed of the electric motor 9 appropriately, and the occurrence of cavitation can be suppressed.

[0129] Also, in this embodiment, when the control device 7 gradually increases the rotation speed of the electric motor 9 according to the control data La and stabilizes it at the target rotation speed Rt, the elapsed time since starting to increase the rotation speed of the electric motor 9 is counted. The actual rotation speed of the electric motor 9 detected by the rotation speed detection device 42 is compared with the control value of the rotation speed of the electric motor 9 indicated by the control data La at predetermined timings, and the rotation speed of the electric motor 9 is controlled so that the actual rotation speed approaches the control value. Thereby, when starting the electric motor 9 with the temperature of the hydraulic oil in a low temperature state, it is possible to prevent the actual rotation speed of the electric motor 9 from increasing rapidly and further suppress the occurrence of cavitation in the hydraulic oil in the hydraulic pumps P1, P2.

[0130] Also, in the present embodiment, the control device 7 divides the section from the start time point t0 of the increase in the rotation speed of the electric motor 9 to the delay time Za into an immediately-after-start section Za1, a middle section Za2, and an immediately-before-end section Za3. In the middle section Za2, the rotation speed of the electric motor 9 is increased in proportion to the elapsed time from the start time point t0. In the immediately-after-start section Za1 and the immediately-before-end section Za3, control data La is created so that the rotation speed of the electric motor 9 changes more gently than in the middle section Za2. Thereby, it is possible to prevent the rotation speed of the electric motor 9 from increasing rapidly immediately after the start of the increase in the rotation speed of the electric motor 9. Also, immediately before the end of the increase in the rotation speed of the electric motor 9, it is possible to prevent the rotation speed of the electric motor 9 from exceeding the target rotation speed Rt and adjust the rotation speed of the electric motor 9 to the target rotation speed Rt. Further, in the middle section Za2, the amount of increase in the rotation speed of the electric motor 9 is larger than in the immediately-after-start section Za1 and the immediately-before-end section Za3. Therefore, it is possible to prevent the time (delay time Za) until the start of the electric motor 9 is completed from becoming unnecessarily long by setting the rotation speed of the electric motor 9 to the target rotation speed Rt.

[0131] Also, in the present embodiment, the electric working machine 1 includes a working device 20, 10 (working device 20, traveling device 10) that operates by the power of hydraulic equipment (hydraulic motors ML, MR, MT, hydraulic cylinders C1 to C5, control valve CV), and operation members 5a, 5b (working operation lever 5a, traveling operation lever 5b) for operating the operation of the working devices 20, 10. The control device 7 prohibits the operation of the working devices 20, 10 by the operation of the operation members 5a, 5b in the immediately-after-start section Za1. Thereby, when the rotation speed of the electric motor 9 is low and the discharge amount of the hydraulic oil from the hydraulic pumps P1, P2 is small, it is possible to prevent the hydraulic equipment (hydraulic motors ML, MR, MT, hydraulic cylinders C1 to C5, control valve CV) or the working devices 20, 10 from malfunctioning in response to the operation of the operation members 5a, 5b.

[0132] Further, in the present embodiment, when the control device 7 increases the rotational speed of the electric motor 9 according to the control data La, if the instruction member 5d is operated, a new target rotational speed Rt is determined according to the operation position of the instruction member 5d. If the new target rotational speed Rt is greater than the actual rotational speed of the electric motor 9 detected by the rotational speed detection device 42, the delay time Za and the control data La are changed according to the new target rotational speed Rt, and the rotational speed of the electric motor 9 is controlled according to the changed control data La.

[0133] As described above, when starting the electric motor 9 according to the control data La while the temperature of the hydraulic oil is in a low temperature state, if a new target rotational speed Rt greater than the actual rotational speed of the electric motor 9 is indicated by the instruction member 5d, the target rotational speed Rt can be changed to the new target rotational speed Rt, and the rotational speed of the electric motor 9 can be gradually increased and set to the new target rotational speed Rt. Further, if a new target rotational speed Rt smaller than the actual rotational speed of the electric motor 9 is indicated by the instruction member 5d, the new target rotational speed Rt can be ignored, and the gradual increase in the rotational speed of the electric motor 9 can be continued according to the control data La, and the rotational speed of the electric motor 9 can be set to the target rotational speed Rt.

[0134] Furthermore, in the present embodiment, the electric working machine 1 includes a display device 43 that displays a notification suggesting that the electric motor 9 is starting during the gradual increase in the rotational speed of the electric motor 9 by the control device 7. Thereby, it is possible to visually notify the operator that it takes time (delay time Za) to start the electric motor 9.

[0135] In the above embodiment, an example of applying the present invention to the electric working machine 1 such as a backhoe has been described. However, the application target of the present invention is not limited to this. For example, it may be applied to other construction machines such as a wheel loader, a compact track loader, and a skid steer loader, or may be applied to agricultural machines such as a tractor, a combine, a rice transplanter, and a lawn mower.

Explanation of Reference Numerals

[0136] 1 Electric working machine 5a Working operation lever (operating member) 5b Traveling operation lever (operating member) 5d Accelerator dial (indicating member) 7 Control device 7b Storage unit (storage device) 9 Electric motor 10 Traveling device (working device) 20 Working device 30 Battery unit 38 Inverter 42 Rotation speed detection device 43 Display device 44 Oil temperature detection device C1 - C5 Hydraulic cylinder (hydraulic equipment) CV Control valve (hydraulic equipment) La, Lah, Lal, Lam Control data Lab Basic control data ML, MR, MT Hydraulic motor (hydraulic equipment) P1, P2 Hydraulic pump Qe Target end point Qeb Basic end point Rt, Rth, Rtl, Rtm Target rotation speed Rtb Basic target rotation speed Za, Zah, Zal, Zam Delay time Za1 Immediately after start interval Za2 Middle interval Za3 Immediately before end interval Zab Basic delay time Zab1 Immediately after start interval Zab2 Middle interval Zab3 Immediately before end interval

Claims

1. A battery unit, an electric motor, an inverter that supplies power from the battery unit to the electric motor to drive the electric motor, a hydraulic pump operated by the power of the electric motor, a hydraulic device operated by the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump, an oil temperature detection device that detects the temperature of the hydraulic oil, a rotation speed detection device that detects the rotation speed of the electric motor, a control device that controls the driving of the inverter and the electric motor, a storage device in which control data indicating a change in the rotation speed of the electric motor for stabilizing the rotation speed of the electric motor at a predetermined target rotation speed with a predetermined delay time is stored in advance, and comprising, when the control device starts the electric motor in a state where the temperature of the hydraulic oil detected by the oil temperature detection device is equal to or lower than a predetermined temperature, the time until the rotation speed of the electric motor reaches the target rotation speed is longer than when starting the electric motor in a state where the temperature of the hydraulic oil is higher than the predetermined temperature, and the rotation speed of the electric motor is gradually increased based on the control data. An electric working machine.

2. A battery unit, an electric motor, an inverter that supplies power from the battery unit to the electric motor to drive the electric motor, a hydraulic pump operated by the power of the electric motor, a hydraulic device operated by the hydraulic pressure of the hydraulic oil discharged from the hydraulic pump, an oil temperature detection device that detects the temperature of the hydraulic oil, a rotation speed detection device that detects the rotation speed of the electric motor, an instruction member operated to instruct the rotation speed of the electric motor, a control device that controls the driving of the inverter and the electric motor, and comprising, when the control device starts the electric motor in a state where the temperature of the hydraulic oil detected by the oil temperature detection device is equal to or lower than a predetermined temperature, the rotation speed indicated by the instruction member is set as the target rotation speed, and the delay time until the rotation speed of the electric motor stabilizes at the target rotation speed is determined. After starting to increase the rotation speed of the electric motor, the rotation speed of the electric motor is gradually increased so that the rotation speed of the electric motor stabilizes at the target rotation speed after the elapse of the delay time. An electric working machine.

3. The electric working machine according to claim 2, wherein the control device calculates the target rotation speed according to an operation position of the instruction member.

4. A storage device is provided that stores in advance basic control data indicating a change in the rotational speed of the electric motor for stabilizing the rotational speed of the electric motor at a predetermined basic target rotational speed by applying a predetermined basic delay time. The control device determines, as the delay time, the time until the rotational speed of the electric motor reaches the target rotational speed when the rotational speed of the electric motor is changed based on the basic control data. The electric working machine according to claim 2.

5. The basic control data is curved data indicating a correlation between the elapsed time from the start of increase in the rotational speed of the electric motor and the rotational speed of the electric motor, and includes a basic end point where the elapsed time is the basic delay time and the rotational speed of the electric motor is the basic target rotational speed. The control device corrects the basic control data so that the basic end point coincides with the target end point where the elapsed time is the delay time and the rotational speed of the electric motor is the target rotational speed, thereby creating control data indicating a change in the rotational speed of the electric motor for stabilizing the rotational speed of the electric motor at the target rotational speed by applying the delay time, and controls the rotational speed of the electric motor based on the control data. The electric working machine according to claim 4.

6. The basic target rotational speed is set to a predetermined maximum rotational speed that can be set for the electric motor. The control device creates the control data by reducing and correcting the basic control data so that the basic end point coincides with the target end point. The electric working machine according to claim 5.

7. The indicating member can indicate the target rotational speed at a plurality of predetermined levels. The electric working machine includes a storage device that stores in advance, for each of the plurality of levels of the target rotational speed, a corresponding delay time and control data indicating a change in the rotational speed of the electric motor for stabilizing the rotational speed of the electric motor at the corresponding target rotational speed by applying the corresponding delay time. The control device controls the rotational speed of the electric motor based on the control data corresponding to the target rotational speed at any level indicated by the indicating member. The electric working machine according to claim 2.

8. When gradually increasing the rotational speed of the electric motor to stabilize it at the target rotational speed, the control device compares the actual rotational speed of the electric motor detected by the rotational speed detection device with the control value of the rotational speed of the electric motor indicated by the control data at each predetermined timing, and controls the rotational speed of the electric motor so that the actual rotational speed approaches the control value. The electric working machine according to any one of claims 1, 5 to 7.

9. Among the immediately-after-start section, the middle section, and the immediately-before-end section obtained by dividing the section from the start point of the increase in the rotational speed of the electric motor to the delay time, in the middle section, the rotational speed of the electric motor is increased in proportion to the elapsed time from the start point of the increase, and in the immediately-after-start section and the immediately-before-end section, the rotational speed of the electric motor is changed more gently than in the middle section. The electric working machine according to claim 1 or 2.

10. A working device operated by the power of the hydraulic equipment, An operating member for operating the operation of the working device, and In the immediately-after-start section, the control device prohibits the operation of the working device by the operation of the operating member. The electric working machine according to claim 9.

11. It includes an indicating member operated to indicate the rotational speed of the electric motor, When the control device is increasing the rotational speed of the electric motor according to the control data with the rotational speed indicated by the indicating member as the target rotational speed, if the indicating member is operated, a new target rotational speed is determined according to the operation position of the indicating member. If the new target rotational speed is greater than the actual rotational speed of the electric motor detected by the rotational speed detection device, the delay time and the control data are changed according to the new target rotational speed, and the rotational speed of the electric motor is controlled according to the changed control data. The electric working machine according to claim 1 or 5.

12. The electric working machine according to claim 1 or 2, further comprising a display device that displays a notification suggesting that the electric motor is starting during the gradual increase in the rotational speed of the electric motor by the control device.

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