Electric construction machinery and cable locking devices

Abstract

The present invention provides an electric construction machine that allows operation while the power supply cable is connected, while preventing damage to the external power supply during operation. [Solution] The electric hydraulic excavator 1 includes a connector lock mechanism 26 that can switch between a locked state in which the connection between the connection part 25 and the power supply cable 19 cannot be released and an unlocked state in which the connection can be released, a controller 28, and an external force sensor 27 that detects external forces applied to the power supply cable 19. The controller 28 has a charging-only mode in which the battery 12 is charged by power from the power supply cable 19 with the electric motor 15 stopped, and a charging-operation mode in which the battery 12 is charged by power from the power supply cable 19 with the electric motor 15 running. In the charging-only mode, the connector lock mechanism 26 is locked, and in the charging-operation mode, the lock state or unlocked state is switched according to the magnitude of the external force detected by the external force sensor 27.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electric construction machine that connects a power supply cable to supply electric power to an electric motor and a battery, and a cable lock device that locks the connection of the power supply cable. BACKGROUND ART

[0002] In a vehicle including an electric motor as a power source and a battery that stores electric power to be supplied to the electric motor, a connector of a power supply cable extending from an external power source may be connected to supply electric power to the electric motor and the battery. For example, Patent Document 1 discloses a vehicle that can charge an on-vehicle battery from the outside, and includes an operation unit for performing an operation to transition the state of the vehicle between a non-travelable state and a travelable state, a connection unit to which a connector of a power supply cable that supplies electric power to the vehicle from the outside is connected, a connector lock mechanism that locks the connector in a state of being connected to the connection unit so as not to come off, and a controller that controls the connector lock mechanism, wherein the controller is configured to unlock the connector lock mechanism when the operation unit is operated to change the state of the vehicle from the non-travelable state to the travelable state.

[0003] In Patent Document 1, the connector lock mechanism locks the connection unit and the connector of the power supply cable, whereby disconnection between the connection unit and the power supply cable due to a reason unintended by the owner of the power supply cable, such as theft, can be prevented. In addition, the connector lock mechanism is unlocked when an operation is performed to change the state of the vehicle to the travelable state, so that the power supply connector can be pulled out from the connection unit as the vehicle travels, and dragging of the power supply cable and damage to the internal electric circuit of the external power source are prevented. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0004] PATENT DOCUMENT 1 JP 2016-48983 A [Overview of the project] [Problems that the invention aims to solve]

[0005] On the other hand, electric construction machinery such as hydraulic excavators are already known, which use an electric motor to drive a hydraulic pump and other components, and then use the pressurized oil discharged from the hydraulic pump to drive multiple actuators to perform various tasks. For example, if the technology described in Patent Document 1 is applied to electric construction machinery, the connector lock mechanism will be released when the electric construction machinery becomes ready to operate.

[0006] However, electric construction machinery sometimes operates with the power cable connector still connected to the connection point. Therefore, if the connector lock mechanism is released during operation, the vibrations from the operation and the weight of the power cable may cause the power cable connector to lose its connection to the connection point and fall off. In that case, the operator would have to stop the electric construction machinery and reattach the connector to the connection point, which is inconvenient.

[0007] The present invention has been made in view of the above circumstances, and its purpose is to provide an electric construction machine and a cable locking device that can prevent the theft of the power supply cable when not in operation, and can perform work with the power supply cable connected while preventing damage to the external power supply when in operation. [Means for solving the problem]

[0008] To achieve the above objective, the present invention comprises a self-propelled vehicle body having a driver's cab, and a work device provided on the vehicle body, wherein the vehicle body includes an electric motor that serves as a power source, a battery that stores power supplied to the electric motor, a connection part to which a power supply cable for supplying power to at least one of the electric motor and the battery is connected, a connector lock mechanism that can switch between a locked state in which the connection between the connection part and the power supply cable cannot be released and an unlocked state in which the connection can be released, and a controller that controls the switching of the state of the connector lock mechanism. [Effects of the Invention]

[0009] According to the present invention, theft of the power supply cable can be prevented when not in use, and work can be performed with the power supply cable connected while preventing damage to the external power supply during work. [Brief explanation of the drawing]

[0010] [Figure 1] This is a left side view showing the overall structure of an electric hydraulic excavator according to one embodiment of the present invention. [Figure 2] This is a rear view of an electric hydraulic excavator, seen from the rear. [Figure 3] This is a schematic cross-sectional view showing the connector locking mechanism that locks the connection between the upper rotating body and the power supply cable connector, as well as the surrounding structure. [Figure 4] This is a functional block diagram showing the electrical configuration that executes the flow of power and signals in an electric hydraulic excavator. [Figure 5] This is a flowchart that shows the control procedure executed by the controller. [Modes for carrying out the invention]

[0011] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In this embodiment, the travel direction of the electric hydraulic excavator will be described as the front-rear direction, and the direction perpendicular to the travel direction will be described as the left-right direction.

[0012] <Overall Configuration of a Hydraulic Excavator> Figure 1 shows the overall structure of the electric hydraulic excavator according to this embodiment. In Figure 1, the electric hydraulic excavator 1 (electric construction machine) comprises a crawler-type lower traveling body 2 that can move in the front and rear directions, and an upper rotating body 3 that is rotatably mounted on the lower traveling body 2. The body of the electric hydraulic excavator 1 is composed of the lower traveling body 2 and the upper rotating body 3. A swing-type working device 4 is provided on the front side of the upper rotating body 3. The electric hydraulic excavator 1 performs tasks such as excavating soil and sand using the working device 4 while rotating the upper rotating body 3.

[0013] The swing-type work device 4 has a swing post 4A that is mounted on the front side of the slewing frame 5 (described later) so as to be able to swing left and right. A boom 4B is mounted on the swing post 4A so as to be able to move up and down, an arm 4C is mounted on the tip of the boom 4B so as to be able to move up and down, and a bucket 4D is mounted on the tip of the arm 4C so as to be able to move up and down. The work device 4 also includes a swing cylinder 4E for swinging the swing post 4A, a boom cylinder 4F for rotating the boom 4B, an arm cylinder 4G for rotating the arm 4C, and a bucket cylinder 4H for rotating the bucket 4D.

[0014] The lower running body 2 is equipped with left and right tracks 2L (see Figure 1 and Figure 2 described later), 2R (see Figure 2 described later), and left and right running motors 40L (see Figure 1) and 40R (not shown) that drive these tracks 2L and 2R.

[0015] The upper rotating body 3 is mounted on the lower traveling body 2 so as to be rotatable via a rotating device (not shown), and rotates on the lower traveling body 2 when a rotating motor (not shown) provided in the rotating device is driven. The upper rotating body 3 has a base rotating frame 5, on which the cab 6, counterweight 10, exterior cover 11, battery 12, etc., described later are mounted.

[0016] Cab 6 (operator's cab) is disposed on the left side of revolving frame 5, and an operator boards therein. Inside cab 6, there are provided a boarding port (not shown) that can be arbitrarily locked by a user, operator's seat 7 on which the operator sits, traveling lever and pedal 8 for controlling the traveling operation of lower traveling structure 2, work operation lever 9 for controlling the revolving operation of upper revolving structure 3 and the operation of work implement 4, and the like.

[0017] Counterweight 10 is provided at the rear end of revolving frame 5, on the rear side of cab 6. Counterweight 10 maintains the weight balance with work implement 4 provided on the front side of revolving frame 5.

[0018] Exterior cover 11 is provided on the front side of counterweight 10 on revolving frame 5. Exterior cover 11 covers, together with counterweight 10, on-board devices such as electric motor 15 (not shown, refer to FIG. 4 described later) serving as the power source of electric hydraulic excavator 1, a hydraulic pump (not shown), and battery 12, which are mounted on revolving frame 5. Battery 12 is disposed on the front side of counterweight 10, and can store electric power to be supplied to electric motor 15.

[0019] <Connection with External Power Supply> Electric motor 15 drives the hydraulic pump with electric power supplied from external power supply 13 or battery 12. In electric hydraulic excavator 1 of the present embodiment, the hydraulic actuators, namely swing cylinder 4E, boom cylinder 4F, arm cylinder 4G, bucket cylinder 4H, traveling motors 40L, 40R, and the revolving motor described above, are driven by pressure oil discharged from the hydraulic pump. Electric power for driving electric motor 15 is supplied from external power supply 13 to electric hydraulic excavator 1. That is, as shown in FIG. 2, connector 18 of power supply cable 19 is connected to connection portion 25 (described later) provided in upper revolving structure 3, whereby electric power from external power supply 13 is supplied via power supply cable 19. The supplied electric power is supplied to electric motor 15 via, for example, charger 16 (not shown, refer to FIG. 4 described later) or the like, and surplus electric power is charged into battery 12.

[0020] <Connection structure of power supply cable> The connection structure of the power supply cable 19, which is the essential part of the present embodiment, will be described with reference to FIG. 3 and the above-mentioned FIG. 2. As shown in FIG. 3, the upper revolving structure 3 of the electric hydraulic excavator 1 is provided with a connection portion 25 for connecting the power supply cable 19, and a connector lock mechanism 26 capable of switching between a locked state where the connection between the connection portion 25 and the power supply cable 19 cannot be released and an unlocked state where the connection can be released.

[0021] <Connection portion> In FIG. 3, the connection portion 25 is attached to a connection portion mounting base 21. The connection portion mounting base 21 constitutes one unit together with the connection portion 25, the connector lock mechanism 26, and an external force sensor 27 to be described later, and this unit is provided on the upper surface of the counterweight 10 on the rear side of the driver's seat 7 (see FIG. 1 and FIG. 2).

[0022] The connection portion 25 is formed of a cylindrical body having a connection terminal (not shown) disposed on the inner peripheral side, and the tip end of the connection portion 25 is an insertion port into which the connector 18 of the power supply cable 19 is inserted and removed. The connection portion 25 extends to the inside of the exterior cover 11, and is electrically connected to a charger 16 (see FIG. 4 described later) via a harness 25A.

[0023] The connection portion mounting base 21 is composed of a mounting portion 21A to which the connection portion 25 is mounted and a fixing portion 21B fixed to the upper surface of the counterweight 10, and has a box-like shape surrounding the connection portion 25 and the connector lock mechanism 26. The mounting portion 21A is provided with a substantially cylindrical portion 21AC that encloses and arranges the connection portion 25 and has an inner diameter slightly larger than the outer diameter of the connector 18.

[0024] <Connector lock mechanism> The connector locking mechanism 26 is provided at a position that becomes the side surface of the connector 18 when the connector 18 is inserted into the connection part 25, and has a locking pin 26A that can move back and forth in the axial direction. At this time, one end of the connector 18 has a locking hole 18A (engaged part) into which the locking pin 26A is inserted, on the side surface of the tip that is inserted into the connection part 25. Note that the engaged part is not limited to the locking hole, but can be any shape that the locking pin 26A can catch on, such as a groove or projection. In addition, the substantially cylindrical portion 21AC of the mounting portion 21A of the connection part mounting base 21 has a communication hole 21a that communicates with the locking hole 18A.

[0025] The connector locking mechanism 26 allows the lock pin 26A to move forward and backward toward the inside of the connector 18 via the communication hole 21a and the lock hole 18A. In other words, the connector locking mechanism 26 is switchable between a locked state, where the lock pin 26A is advanced and protrudes through the communication hole 21a and inserted into the lock hole 18A, and an unlocked state, where the lock pin 26A is retracted and withdrawn from both the lock hole 18A and the communication hole 21a. In other words, the lock pin 26A is configured to move back and forth between a protruding position, where it protrudes toward the lock hole 18A of the connector 18 of the power supply cable 19 when it is connected to the connection part 25, locking the connection between the connection part 25 and the power supply cable 19, and a retracted position, where it is retracted from the lock hole 18A in the unlocked state, releasing the lock on the connection between the connection part 25 and the power supply cable 19. The lock pin 26A is switched between a locked and unlocked state by a control signal from a controller 28 (not shown; see Figure 4 below) installed inside the electric hydraulic excavator 1. In other words, the controller 28 controls the state of the connector lock mechanism 26.

[0026] When the connector 18 of the power supply cable 19 is inserted into the connection part 25, the lock pin 26A is driven forward to enter the locked state, preventing the connector 18 from being pulled out of the connection part 25 (because the lock pin 26A is inserted into the lock hole 18A). From this state, the lock pin 26A is driven backward to enter the unlocked state, allowing the connector 18 to be freely inserted into and removed from the connection part 25.

[0027] <External force sensor> The mounting portion 21A and the fixing portion 21B have overlapping portions in the thickness direction of each other. The overlapping region of the mounting portion 21A is formed as a flange portion 21AF, and the overlapping region of the fixing portion 21B is formed as a flange portion 21BF. The external force sensor 27 (external force detector) is positioned between these flange portions 21AF and 21BF.

[0028] For example, when the electric hydraulic excavator 1 performs travel or rotation operations while the connector 18 of the power supply cable 19 is plugged into the connection part 25, an external force (tension) in the pulling direction is generated in the power supply cable 19 connected to the electric hydraulic excavator 1 and the external power supply 13. When an external force in the pulling direction is generated on the power supply cable 19 (see arrow A in Figure 3), that external force acts on the external force sensor 27 (see arrow C in Figure 3). In other words, the tension applied to the power supply cable 19 acts on the external force sensor 27. More specifically, the external force (tension) applied to the power supply cable 19 is transmitted to the lock pin 26A via the lock hole 18A of the connector 18 (see arrow A in Figure 3), and further transmitted to the flange portion 21AF via the substantially cylindrical portion 21AC, which has a communication hole 21a through which the lock pin 26A passes, and acts on the external force sensor 27 as a pressing force between the flange portion 21BF, which is the fixed side (see arrow C in Figure 3). In this example, the external force sensor 27 is composed of a known strain gauge attached to an appropriate location on the upper rotating body 3 or the lower traveling body 2. The external force sensor 27 outputs a voltage value (or current value) corresponding to the magnitude of the pressing force (in other words, the external force of the power supply cable 19) to a controller 28 (not shown; see Figure 4 below) installed inside the electric hydraulic excavator 1. The controller 28 can obtain the value of the external force acting on the power supply cable 19 by performing known calculation processing on the voltage value (or current value). As a result, when the controller 28 is in charging operation mode, it can switch between a locked state and an unlocked state depending on the voltage value output from the strain gauge.

[0029] The connector locking mechanism 26, external force sensor 27, and controller 28 described above constitute the cable locking device in this embodiment.

[0030] <Electrical Configuration> Figure 4 shows a functional block diagram representing the electrical configuration that executes the power flow and signal flow described above in the electric hydraulic excavator 1.

[0031] <Controller control mode> In Figure 4, the electric hydraulic excavator 1 of this embodiment has a controller 28 that includes multiple control modes, including a charging-only mode, a charging operation mode, and a battery operation mode.

[0032] <Switches related to mode switching> In this embodiment, in relation to the switching of the above modes by the controller 28, the following are provided at appropriate locations within the cab 6: a machine start switch 30 (so-called key switch) for starting the electric hydraulic excavator 1, and a charging switch 29 for charging the battery 12 when the connector 18 is plugged into the connection part 25 and power is supplied from the external power source 13. Note that the placement of these switches 30 and 29 is not necessarily limited to within the cab 6.

[0033] The vehicle start switch 30 (start switch) consists of a key cylinder and a key that can be inserted into the key cylinder, and outputs a signal to the controller 28 according to the rotation position of the key (OFF position, ON position, or START position). The charging switch 29 instructs whether to turn the battery charging control ON or OFF, and outputs a signal to the controller roller 28 according to its operating position (OFF position or ON position). These switches 29 and 30 may be provided as mechanical switches located inside the cab 6, as described above, or as display switches that can be operated by touch on a touch panel located inside the cab 6.

[0034] <Charging-only mode> The charging-only mode is a control mode for charging the battery 12 using power from the power supply cable 19 while the electric motor 15 is stopped (without stopping the supply of hydraulic fluid to the hydraulic actuator or performing excavation work, etc., by the work device 4). The controller 28 switches to a charging-only mode when the hydraulic excavator 1 is stopped by the vehicle start switch 30 and charging of the battery 12 is started by the charging switch 29. Specifically, the controller 28 determines, for example, that the vehicle start switch 30 is in the OFF position based on the voltage value of the signal from the vehicle start switch 30, that the charging switch 29 has been operated to the ON position based on the voltage value of the signal from the charging switch 29, and that the power supply cable 19 is connected based on the detection result of the cable connection detection circuit (not shown), and then performs battery charging control in the charging-only mode. In this charging-only mode, the controller 28 controls the connector locking mechanism 26 to the locked state described above.

[0035] <Charging Operation Mode> The charging operation mode is a mode in which power is supplied from an external power source 13 to the electric motor 15 and the battery 12. In other words, it is a control mode for charging the battery 12 using power from the power supply cable 19 while the electric motor 15 is running.

[0036] The controller 28 switches to charging operation mode when the hydraulic excavator 1 is started using the vehicle start switch 30. In particular, it switches to charging operation mode when the hydraulic excavator 1 is started using the vehicle start switch 30 and the connection of the power supply cable 19 is detected. Specifically, the controller 28 determines, for example, that the vehicle start switch 30 has been operated to the START position based on the voltage value of the signal from the vehicle start switch 30, that the charging switch 29 has been operated to the OFF position based on the voltage value of the signal from the charging switch 29, and that the power supply cable 19 is connected based on the detection result of a cable connection detection circuit (not shown) of an appropriate configuration, and then starts driving the electric motor 15 with power from the external power supply 13 in the charging operation mode. In this charging operation mode, the controller 28 selectively switches the connector lock mechanism 26 to either the locked state or the unlocked state depending on the magnitude of the external force detected by the external force sensor 27 (in other words, depending on the magnitude of the voltage or current value from the strain gauge).

[0037] <Battery operation mode> The battery operation mode is a mode in which the connector lock mechanism 26 is unlocked, disconnecting the connection part 25 and the power supply cable 19, and power stored in the battery 12 is supplied to the electric motor 15. The controller 28 switches to battery operation mode when the hydraulic excavator 1 is started by the vehicle start switch 30 and the connection of the power supply cable 19 is not detected. Specifically, the controller 28 determines, for example, that the vehicle start switch 30 has been operated to the START position based on the voltage value of the signal from the vehicle start switch 30, that the charging switch 29 has been operated to the OFF position based on the voltage value of the signal from the charging switch 29, and that the power supply cable 19 is not connected based on the detection result of the cable connection detection circuit, and in this battery operation mode, starts driving the electric motor 15 with power from the battery 12.

[0038] <Control Flow> In this embodiment, the controller 28 switches between three modes—a dedicated charging mode, a charging operation mode, and a battery operation mode—depending on the operating status (ON or OFF) of the machine activation switch 30 and the charging switch 29. When the dedicated charging mode is activated, the controller 28 locks the connector lock mechanism 26. When the charging operation mode is activated, the controller 28 switches the lock state of the connector lock mechanism 26 or the unlock state depending on the magnitude of the external force detected by the external force sensor 27.

[0039] Figure 5 shows a flowchart illustrating the control procedure executed by the controller 28 to achieve the above processing. In Figure 5, first, in S5, it is determined whether the above-mentioned aircraft activation switch 30 is in the ON state or not. If it is in the OFF state, S5 is determined to be NO, and the process proceeds to S40, which will be described later. If it is in the ON state, S5 is determined to be YES, and the process proceeds to S10.

[0040] In S10, the signal from the charging switch 29 is de-identified (not recognized). Then, the process moves on to S20.

[0041] In S20, it is determined whether the external force on the power supply cable 19 detected by the external force sensor 27 is below a predetermined threshold. This threshold is a value that, if the external force on the power supply cable 19 is below this value, is estimated to prevent damage to the power supply cable 19 itself and the internal circuitry of the external power supply 13 connected to the power supply cable 19, thus ensuring durability. This threshold is set in advance using an appropriate method and stored in the controller 28 (or at an appropriate location outside the controller 28). If the external force exceeds the threshold mentioned above, S20 is judged as NO, and the process proceeds to S35, which will be described later. If the external force is below the threshold mentioned above, S20 is judged as YES, and the process proceeds to S25.

[0042] In S25, it is determined whether the charger 16 is sensing the power supply voltage. That is, it is determined whether the connector 18 is inserted deeply into the connection part 25 until it can conduct power to the connection terminals in the connection part 25, and whether power is being supplied to the charger 16 from the power supply cable 19. If the power supply voltage is not sensed, S25 is determined to be NO, and in S60 the control mode becomes the "battery operation mode". In other words, the system switches to "battery operation mode" only when the aircraft start switch 30 is ON and the power supply cable 19 is not connected. After that, the process returns to S5, and the same procedure as described above is repeated. If the power supply voltage is detected, S25 will be judged as YES, and in S15 the control mode will be set to "charging operation mode". In other words, if the above-mentioned machine start switch 30 is ON and the power supply cable 19 is connected, the system will switch to "charging operation mode" regardless of whether the charging switch 29 is ON or OFF. After that, the process moves on to S30.

[0043] In S30, the lock pin 26A of the connector lock mechanism 26 is driven forward and inserted into the lock hole 18A, thus achieving the locked state. In this state, the controller 28 instructs the charger 16 to begin charging (if the lock pin 26A is already in the locked state and the charger 16 is charging, that state is maintained). The process then returns to S5, and the same procedure as described above is repeated.

[0044] Furthermore, in S35, which follows a NO determination in S20, the lock pin 26A of the connector lock mechanism 26 is driven backward and removed from the lock hole 18A, resulting in the unlocked state described above. In this state, the controller 28 instructs the charger 16 to stop charging (not to perform charging) (if the lock pin 26A is already in the unlocked state and the charger 16 has stopped charging, that state is maintained). After that, the process returns to S5, and the same procedure as described above is repeated.

[0045] Furthermore, after switching to "charging operation mode" in S15, the lock state or unlock state of the connector lock mechanism 26 is switched according to the magnitude of the external force detected by the external force sensor 27, which is an external force detector. Specifically, although the connector lock mechanism 26 is locked in S30 after S15, when the processing from S5 is executed again thereafter, after the magnitude of the external force is determined in S20, if the determination in S20 is NO, the connector lock mechanism 26 is switched to the unlock state in S35.

[0046] For example, if the power supply cable 19 is pulled while the S15 is in "charging work mode", it will switch to "battery work mode" in the following sequence. In other words, as described above, S5 is judged as YES, and after S10, S20 and S25 are judged as YES, and in S15, the system switches to the charging operation mode, and then after S30, the process from S5 is executed again. At that time, if the power supply cable 19 is subjected to a load and pulled as described above, and the power supply cable 19 is disconnected, then after S5 and S10, S20 is judged as NO, and in S35, as described above, the connector lock mechanism 26 is released, and charging is stopped (not performed). Subsequently, when the process from S5 is executed again, S20 is determined to be YES because no load is placed on the external force sensor 27 after the power supply cable 19 is disconnected, S25 is determined to be NO because the power supply cable 19 is disconnected, and the system transitions to battery operation mode in S60.

[0047] On the other hand, in S40, which is the next step after S5 is judged as NO, it is determined whether the charging switch 29 is in the ON state or not. If it is in the OFF state, S40 is judged as NO, and the process moves to S35, where the process described above is performed. If it is in the ON state, S40 is judged as YES, and the process moves to S50.

[0048] In S50, as with S25 above, it is determined whether or not the charger 16 is sensing the power supply voltage. If the power supply voltage is not sensed, S50 is judged as NO, and the process moves to S35, where the process described above is performed. If the power supply voltage is sensed, S50 is judged as YES, and the process moves to S45, where the control mode becomes "charging-only mode". In other words, the device switches to "charging-only mode" only when the above-mentioned device activation switch 30 is OFF, the charging switch 29 is ON, and the power supply cable 19 is connected. After that, the process moves to S55.

[0049] In S55, the connector lock mechanism 26 is locked, similar to S30 above. The controller 28 also instructs the charger 16 to begin charging (if the charger 16 is already charging in the locked state, that state is maintained). The process then returns to S5, and the same procedure as described above is repeated.

[0050] On the other hand, if S40 is determined to be NO, the process proceeds to S35 as described above, and the aforementioned process is performed.

[0051] <Effects of the Embodiment> In the electric hydraulic excavator 1 of this embodiment, a connector lock mechanism 26 is provided that can lock the connection between the connection part 25 and the power supply cable 19. For example, when the excavator is not in operation, the power supply cable 19 can be locked with the connector lock mechanism 26 to prevent theft of the power supply cable 19.

[0052] On the other hand, the controller 28 that controls the connector lock mechanism 26 has at least two control modes: a charging-only mode and a charging-operation mode. In the charging-operation mode, the controller 28 switches the lock state or unlock state of the connector lock mechanism 26 according to the magnitude of the external force detected by the external force sensor 27 (see S30 and S35 in Figure 5).

[0053] As a result, the controller 28 locks the connector locking mechanism 26 up to a certain magnitude of external force (i.e., external force below the aforementioned threshold), allowing the power supply cable 19 to remain connected to the connection part 25 while the work is being performed (see S30). In other words, the electric hydraulic excavator 1 can perform work while receiving power from the external power supply 13 without the connector 18 coming loose from the connection part 25. For example, if excessive external force (=external force exceeding the aforementioned threshold) is applied to the power supply cable 19 when the electric hydraulic excavator 1 performs a travel or rotation operation while the connector 18 of the power supply cable 19 is plugged into the connection part 25, the controller 28 will release the connector lock mechanism 26, causing the connector 18 to detach from the connection part 25 in accordance with the external force (see S35). This prevents damage to the power supply cable 19 and the external power supply connected via the power supply cable 19.

[0054] In this embodiment, a strain gauge capable of outputting a voltage value corresponding to the magnitude of the external force is used as the external force sensor 27. When the charging operation mode is active, the controller 28 switches the lock state or unlock state of the connector lock mechanism 26 according to the voltage value output from the strain gauge. For example, if the voltage value output from the strain gauge is within a predetermined value, the controller 28 can assume that the external force on the power supply cable 19 is within a certain magnitude (= below the threshold) and lock the connector lock mechanism 26. Alternatively, if the voltage value output from the strain gauge exceeds the predetermined value, the controller 28 can assume that an excessive external force (= an external force exceeding the threshold) has been applied to the power supply cable 19 and unlock the connector lock mechanism 26.

[0055] Furthermore, in this embodiment in particular, the lock pin 26A of the connector lock mechanism 26 is configured to move back and forth between a protruding position, which protrudes from the lock hole 18A of the connector 18 of the power supply cable 19 when it is connected to the connection part 25 to lock the connection between the connection part 25 and the power supply cable 19, and a retracted position, which retracts from the lock hole 18A when the lock is released to release the lock on the connection between the connection part 25 and the power supply cable 19. With this configuration, when the lock is released, the lock pin 26A is inserted into the lock hole 18A of the connector 18 of the power supply cable 19 to mechanically connect the connection part 25 and the power supply cable 19, thereby locking them in a state where they cannot be separated.

[0056] In this embodiment, the cab 6 is equipped with two switches: a machine start switch 30 and a charging switch 29. The controller 28 switches to a charging-only mode when the hydraulic excavator 1 is stopped by the machine start switch 30 and charging of the battery 12 is started by the charging switch 29. On the other hand, the controller 28 switches to a charging operation mode when the hydraulic excavator 1 is started by the machine start switch 30. In other words, the controller 28 switches to a charging operation mode in such a manner that the operation state of the machine start switch 30 takes precedence over the operation state of the charging switch 29 (see S10 and S15 in Figure 5). As a result, when operating the electric hydraulic excavator 1, the operator can switch the controller 28 to charging operation mode simply by turning on the machine start switch 30, and can lock or unlock the connector locking mechanism 26 depending on the magnitude of the external force. For example, if the charging switch 29 is turned ON first, and then the aircraft activation switch 30 is turned ON, in the sequence of the charging-only mode (S40→S50→S45→S55→S5→...), S5 will be judged as YES, and the system will transition to the charging operation mode via S10 and then to S15.

[0057] On the other hand, if the operator does not want to perform any work with the electric hydraulic excavator 1 and only wants to charge the battery 12, the operator turns the machine start switch 30 to the OFF position and the charge switch 29 to the ON position. This puts the controller 28 into a dedicated charging mode (see S45 in Figure 5), allowing power from the power supply cable 19 to be supplied to the battery 12 for charging. For example, if the machine start switch 30 is turned ON and the charging switch 29 is also turned ON (this ON operation is not identified by S10), and then the machine start switch 30 is turned OFF, then in the flow of the charging work mode from S5→S10→S20→S25→S15→S30..., S5 will be judged as NO, and the system will transition to the charging-only mode via S40 to S45. In other words, even after the excavation work is completed in the charging work mode and the operator turns the machine start switch 30 OFF by performing a so-called key OFF operation, the system can automatically transition to a mode that only performs charging.

[0058] Furthermore, when the electric hydraulic excavator 1 is in charging-only mode, the connector lock mechanism 26 will not release unless the user turns off the charging switch 29 to stop charging, thus preventing the connector 18 from coming loose from the connection part 25. As a result, for example, if the operator locks the entrance to the cab 6, it becomes impossible for anyone else to turn off the charging switch 29, thus preventing the removal of the power supply cable 19 for reasons unintended by the user, such as theft of the power supply cable 19.

[0059] Furthermore, in this embodiment, the controller 28 has not only the charging-only mode and the charging-operating mode as control modes, but also a battery-operating mode. As described above, the controller 28 switches to battery-operating mode when the hydraulic excavator 1 is started by the vehicle start switch 30 and the connection of the power supply cable 19 is not detected. On the other hand, when the hydraulic excavator 1 is started by the vehicle start switch 30 and the connection of the power supply cable 19 is detected, it switches to charging-operating mode. As a result, when operating the electric hydraulic excavator 1 by supplying power already stored in the battery 12 to the electric motor 15 without connecting the power supply cable 19, the operator can switch the controller 28 to battery operation mode by turning on the machine start switch 30 with the power supply cable 19 disconnected (see S60 in Figure 5).

[0060] In the above explanation, the example given was that the hydraulic excavator 1 itself is equipped with a connector locking mechanism 26, but this is not the only example. In other words, the connector 28 itself may be equipped with a connector locking mechanism (pin lock). Furthermore, although the above description uses the electric hydraulic excavator 1 as an example of an electric construction machine, it is not limited to this. The present invention may also be applied to other construction machines other than hydraulic excavators, such as wheel loaders and crawler cranes, as long as they use an electric motor as a power source. In this case as well, the same effects as described above will be obtained.

[0061] Furthermore, the arrows shown in Figure 4 represent only one example of signal flow and do not limit the direction of signal flow.

[0062] Furthermore, the flowchart shown in Figure 5 does not limit the present invention to the procedures shown in the flowchart above, and additional or deleted procedures or changes in order are permitted without departing from the spirit and technical idea of ​​the invention. [Explanation of Symbols]

[0063] 1. Electric hydraulic excavator (electric construction machine) 2. Lower running body (vehicle body) 3. Upper rotating body (vehicle body) 4. Working equipment 6. Cab (driver's cabin) 12 batteries 13 External power supply 15 Electric motor 16 charger 18 connectors 18A Locking hole (engaged portion) 19 Power supply cable 25 Connection part 26 Connector locking mechanism 26A Locking Pin 27. External force sensors (external force detectors, strain gauges) 28 Controllers 29 Charging switch 30. Aircraft activation switch (activation switch)

Claims

1. It comprises a self-propelled vehicle body having a driver's cab, and a work device installed on the vehicle body, The aforementioned vehicle body is The electric motor serves as the power source, A battery for storing the power supplied to the electric motor, A connection part to which a power supply cable for supplying power to at least one of the electric motor and the battery is connected, A connector locking mechanism that can switch between a locked state in which the connection between the connection part and the power supply cable cannot be released and an unlocked state in which the connection can be released, A controller that performs control to switch the state of the connector locking mechanism, In an electric construction machine having, The system includes an external force detector that detects the external force applied to the power supply cable connected to the connection part, The aforementioned controller, The system has multiple control modes, including a dedicated charging mode in which the battery is charged using power from the power supply cable while the electric motor is stopped, and a charging operation mode in which the battery is charged using power from the power supply cable while the electric motor is running. In the charging-only mode, the connector lock mechanism is set to the locked state. In the charging operation mode, the lock state or unlock state of the connector lock mechanism is switched according to the magnitude of the external force detected by the external force detector. An electric construction machine characterized by the following features.

2. In the electric construction machine according to claim 1, The external force detector is a strain gauge attached to the vehicle body and capable of outputting a voltage value corresponding to the magnitude of the external force. In the charging operation mode, the controller The locked state or the unlocked state is switched according to the voltage value output from the strain gauge. An electric construction machine characterized by the following features.

3. In the electric construction machine according to claim 1, The connector locking mechanism is A protruding position that protrudes from the engaged portion of the connector of the power supply cable when it is connected to the aforementioned connection portion, thereby locking the connection between the connection portion and the power supply cable, The unlocked state includes a retracted position where the lock pin is retracted from the engaged portion, thereby releasing the lock on the connection between the connecting portion and the power supply cable, and a lock pin that can move back and forth between these positions. An electric construction machine characterized by the following features.

4. In the electric construction machine according to claim 1, A start switch for starting the aforementioned electric construction machine, A charging switch for charging the aforementioned battery, Equipped with, The aforementioned controller, When the electric construction machine is started using the aforementioned start switch, it switches to the charging operation mode. The electric construction machine is stopped by the start switch, and the charging switch is activated to start charging the battery, at which point the machine switches to the charging-only mode. An electric construction machine characterized by the following features.

5. In the electric construction machine according to claim 4, The aforementioned control mode is The battery operation mode includes a state in which the connector locking mechanism is in the unlocked state and power stored in the battery is supplied to the electric motor. The aforementioned controller, When the start operation of the electric construction machine is performed by the start switch and the connection of the power supply cable is detected, the machine switches to the charging operation mode. When the start operation of the electric construction machine is performed by the start switch, and the connection of the power supply cable is not detected, the machine switches to the battery operation mode. An electric construction machine characterized by the following features.

6. An electric construction machine having an electric motor, a battery for storing power supplied to the electric motor, and a connection part to which a power supply cable for supplying power to at least one of the electric motor and the battery is connected, and a connector lock mechanism that can switch between a locked state in which the connection part and the power supply cable cannot be released and an unlocked state in which the connection can be released, A controller that performs control to switch the state of the connector locking mechanism, In a cable locking device equipped with, It has an external force detector that detects the external force applied to the power supply cable connected to the connection part, The aforementioned controller, The system has multiple control modes, including a dedicated charging mode in which the battery is charged using power from the power supply cable, and a charging operation mode in which the battery is charged while power from the power supply cable is supplied to the electric motor. In the charging-only mode, the connector lock mechanism is set to the locked state. In the charging operation mode, the lock state or unlock state of the connector lock mechanism is switched according to the magnitude of the external force detected by the external force detector. A cable locking device characterized by the following features.

Images