Electric construction machinery

Abstract

Provided is an electric construction machine with which damage to a power supply cable can be reduced. An electric shovel of the present invention comprises: a turning angle sensor that detects the turning angle of a turning body; a cable stand disposed on the turning body, and having a holding part that holds a power supply cable; a rotation angle sensor that detects the rotation angle of the holding part of the cable stand; a turning lock valve; and a controller. The controller calculates the position of the holding part of the cable stand on the basis of the detection results from the turning angle sensor and the rotation angle sensor when a state in which the power supply cable is connected to a power supply port is detected by a connection sensor. Then, when the calculated position of the holding part is out of a predetermined range, the turning lock valve is controlled into a shut-off state to prohibit the turning body from turning.

Description

Technical Field

[0001] The present invention relates to a construction machine driven by electricity to which a power supply cable can be connected.

Background Art

[0002] An electric excavator, which is one type of construction machine driven by electricity, includes, for example, a traveling body, a revolving body rotatably provided above the traveling body, a working device connected to the front side of the revolving body, an electric motor mounted on the revolving body, a hydraulic pump mounted on the revolving body and driven by the electric motor, and a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump. In the electric excavator, there is a configuration in which a power supply cable can be connected to the revolving body side, and power from an external power source is supplied via the power supply cable. Then, the electric motor is driven by the power supplied via the power supply cable. Alternatively, the battery mounted on the revolving body is charged by the power supplied via the power supply cable, and the electric motor is driven by the power of the battery.

[0003] The electric excavator of Patent Document 1 is configured such that when a power supply cable is connected, the operation of the excavator (specifically, the revolving operation or the traveling operation) cannot be performed. Thereby, it is possible to prevent damage to the power supply cable.

[0004] The electric excavator of Patent Document 2 is configured such that when a power supply cable is connected, the operation of the excavator can be performed, and it includes a cable stand for suppressing damage to the power supply cable. The cable stand is disposed on the rear side of the revolving body (in other words, on the opposite side to the working device), has a gripping portion for gripping the power supply cable, and is configured such that the gripping portion can rotate around a vertical axis. Then, for example, in response to the revolution of the revolving body, the gripping portion of the cable stand rotates in the opposite direction, so that an excessive load is not applied to the power supply cable.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Patent No. 4504940 [Patent Document 2] Japanese Patent Publication No. 2018-084099 [Overview of the project] [Problems that the invention aims to solve]

[0006] By adopting the cable stand described in Patent Document 2, it is possible to operate the shovel while the power supply cable is connected, while minimizing damage to the power supply cable. However, depending on the rotation angle of the slewing body, the position of the gripping part of the cable stand may change significantly, and the power supply cable gripped by the cable stand may come into contact with the vehicle and be damaged. Also, depending on the position of the gripping part of the cable stand and the direction of travel of the vehicle, the power supply cable gripped by the cable stand may be run over and damaged by the movement of the vehicle.

[0007] The present invention has been made in view of the above matters, and its purpose is to provide an electric construction machine that can suppress damage to power supply cables. [Means for solving the problem]

[0008] To achieve the above objective, a representative example of the present invention is an electric construction machine comprising: a traveling body; a slewing body rotatably provided above the traveling body; a work device connected to the slewing body; a power supply port disposed on the slewing body to which a power supply cable from an external power source is connected; and a cable stand disposed on the slewing body having a gripping portion for gripping the power supply cable, configured such that the gripping portion can rotate around a vertical axis, wherein the present invention comprises: a connection sensor for detecting when the power supply cable is connected to the power supply port; a slewing angle sensor for detecting the slewing angle of the slewing body; a rotation angle sensor for detecting the rotation angle of the gripping portion of the cable stand; a slewing lock device for locking the slewing body to prevent its rotation; and a controller for controlling the slewing lock device, wherein when the connection sensor detects that the power supply cable is connected to the power supply port, the controller calculates the position of the gripping portion of the cable stand based on the detection results of the slewing angle sensor and the rotation angle sensor, and the calculated position of the gripping portion of the cable stand The power supply cable, which is gripped by the gripping portion of the cable stand, does not come into contact with the traveling body. When the vehicle moves outside a predetermined range, the swivel locking device is controlled to a locked state. [Effects of the Invention]

[0009] According to the present invention, damage to power supply cables caused by the operation of electric construction machinery can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side view showing the structure of an electric excavator in the first embodiment of the present invention. [Figure 2] This is a top view showing the structure of the rotating body of an electric excavator in the first embodiment of the present invention. [Figure 3] This diagram shows the configuration of the swing motor in the drive system of an electric excavator according to the first embodiment of the present invention. [Figure 4] This figure shows the configuration of the electrical system of an electric excavator in the first embodiment of the present invention. [Figure 5]This is a flowchart illustrating the contents of the swivel lock control in the first embodiment of the present invention. [Figure 6A] This is a top view illustrating a specific example of the operation of an electric shovel in the first embodiment of the present invention, and also showing a predetermined range set with respect to the position of the gripping portion of the cable stand. [Figure 6B] This is a top view illustrating a specific example of the operation of an electric shovel in the first embodiment of the present invention, and also showing a predetermined range set with respect to the position of the gripping portion of the cable stand. [Figure 7] This figure shows the configuration of the electrical system of an electric excavator in a first modified example of the present invention. [Figure 8] This is a top view showing a predetermined range set with respect to the position of the gripping portion of the cable stand in a first modified example of the present invention. [Figure 9A] This is a top view showing a specific example of the operation of an electric shovel in the first modified version of the present invention. [Figure 9B] This is a top view showing a specific example of the operation of an electric shovel in the first modified version of the present invention. [Figure 10] This figure shows the configuration of the drive system for an electric excavator in a second embodiment of the present invention, specifically the configuration related to the travel motor. [Figure 11] This figure shows the configuration of the electrical system of an electric excavator in a second embodiment of the present invention. [Figure 12] This is a flowchart illustrating the contents of the travel lock control in the second embodiment of the present invention. [Figure 13A] This is a top view illustrating a specific example of the operation of an electric shovel in a second embodiment of the present invention, as well as showing the first and second ranges set with respect to the position of the gripping portion of the cable stand. [Figure 13B] This is a top view showing a specific example of the operation of an electric shovel in a second embodiment of the present invention. [Figure 14] This figure shows the configuration of the electrical system of an electric excavator in a second modified example of the present invention. [Figure 15]It is a top view showing the first and second ranges set with respect to the position of the gripping part of the cable stand in the second modification of the present invention. [Figure 16A] It is a top view showing a specific example of the operation of the electric shovel in the second modification of the present invention. [Figure 16B] It is a top view showing a specific example of the operation of the electric shovel in the second modification of the present invention.

Embodiments for Carrying out the Invention

[0011] The first embodiment of the present invention will be described while referring to the drawings.

[0012] FIG. 1 is a side view showing the structure of the electric shovel in the present embodiment. FIG. 2 is a top view showing the structure of the revolving body of the electric shovel in the present embodiment. In FIG. 2, in order to show the equipment mounted on the revolving body, a state in which a part of the exterior cover of the revolving body is removed is shown.

[0013] The electric shovel of the present embodiment includes a traveling body 11, a revolving body 12 provided rotatably above the traveling body 11, and a working device 13 connected to the front side (left side in FIG. 1) of the revolving body 12. The revolving body 12 rotates by the rotation of a revolving motor 14, and its revolving angle is detected by a revolving angle sensor 15 (see FIG. 4 described later).

[0014] The traveling body 11 includes, for example, an H-shaped truck frame 16 when viewed from above, a driving wheel 17 disposed at the rear end on the left side (front side with respect to the paper surface of FIG. 1) of the truck frame 16, a driven wheel 18 disposed at the front end on the left side of the truck frame 16, a left crawler belt 19 wound around the left driving wheel 17 and the driven wheel 18, and a left traveling motor 20A that drives the left driving wheel 17 (and thus the left crawler belt 19).

[0015] Furthermore, the running body 11 includes a drive wheel (not shown) located at the rear end of the right side (far side relative to the plane of the paper in Figure 1) of the track frame 16, a driven wheel (not shown) located at the front end of the right side of the track frame 16, a right-side track wrapped around the right-side drive wheel and driven wheel, and a right-side running motor 20B (see diagram below) that drives the right-side drive wheel (and consequently, the right-side track).

[0016] The working device 13 includes, for example, a swing post 21 rotatably connected to the front of the slewing body 12 in the left-right direction, a boom 22 rotatably connected to the upper side of the swing post 21 in the up-down direction, an arm 23 rotatably connected to the tip of the boom 22 in the up-down direction, and a bucket 24 rotatably connected to the tip of the arm 23 in the up-down direction. The swing post 21 rotates by the extension and retraction of a swing cylinder (not shown), the boom 22 rotates by the extension and retraction of a boom cylinder 25, the arm 23 rotates by the extension and retraction of an arm cylinder 26, and the bucket 24 rotates by the extension and retraction of a bucket cylinder 27.

[0017] The rotating body 12 comprises a rotating frame 28 that forms the lower base structure, a cab (driver's compartment) 29 provided on the left side of the rotating frame 28 (the front side in the plane of the paper in Figure 1, and the lower side in Figure 2), and a counterweight 30 provided on the rear side of the rotating frame 28 (the right side in Figures 1 and 2).

[0018] Furthermore, the rotating body 12 is positioned above the counterweight 30 and includes a power supply port 31 to which a power supply cable 2 from an external power source 1 (e.g., commercial power) is connected, a connection sensor 32 for detecting when the power supply cable 2 is connected to the power supply port 31, and a cable stand 33 provided above the counterweight 30 to guide the power supply cable 2.

[0019] The cable stand 33 comprises a rotating shaft 34 supported so as to be rotatable around a vertical axis, a support frame 35 extending horizontally from the rotating shaft 34, a gripping part 36 (clamp) provided on the tip side of the support frame 35 for gripping the power supply cable 2, and a rotation angle sensor 37 (see Figure 4 described later) for detecting the rotation angle of the rotating shaft 34, i.e., the rotation angle of the gripping part 36.

[0020] For example, when the slewing body 12 rotates clockwise relative to the traveling body 11 when viewed from above, the gripping portion 36 of the cable stand 33 rotates counterclockwise relative to the slewing body 12 when viewed from above. Also, for example, when the slewing body 12 rotates counterclockwise relative to the traveling body 11 when viewed from above, the gripping portion of the cable stand 33 rotates clockwise relative to the slewing body 12 when viewed from above. This prevents excessive load from being placed on the power supply cable 2. However, to avoid contact between the gripping portion 36 of the cable stand 33 and the cab 29, etc., the rotation range of the rotating shaft 34, i.e., the rotation range of the gripping portion 36, is limited by a stopper (not shown).

[0021] In this embodiment, the rotation angle of the gripping portion 36 of the cable stand 33 is defined as the reference value (0 degrees) of the rotation angle when the gripping portion 36 is facing the rear of the swivel body 12 (see Figures 1 and 2). When the rotation angle of the gripping portion 36 is defined to increase as it rotates clockwise from the aforementioned state, the rotation angle of the gripping portion 36 is limited to, for example, 90 degrees. Also, when the rotation angle of the gripping portion 36 is defined to increase as it rotates counterclockwise from the aforementioned state, the rotation angle of the gripping portion 36 is limited to, for example, 90 degrees.

[0022] The cab 29 is equipped with a driver's seat (not shown) where the driver sits. In front of the driver's seat are the driver-operated drive levers and pedals 38A and 38B (see Figure 10 below). The driver-operated drive levers and pedals 38A and 38B control the movement of the vehicle body 11 by operating them in the forward and backward directions. To the right of the drive levers and pedals 38A and 38B is a driver-operated swing control pedal (not shown). The driver-operated swing control pedal controls the movement of the swing post 21 by operating it in the left and right directions.

[0023] On the left side of the driver's seat, there is a work control lever 39 (see Figure 3 below) that can be operated by the driver. The work control lever 39 controls the movement of the slewing body 12 by operating it left and right, and controls the movement of the arm 23 by operating it forward and backward. On the right side of the driver's seat, there is a work control lever (not shown) that can be operated by the operator. This work control lever controls the movement of the bucket 24 by operating it left and right, and controls the movement of the boom 22 by operating it forward and backward.

[0024] The electric excavator is equipped with a drive system that drives multiple hydraulic actuators (specifically, the slewing motor 14, travel motors 20A and 20B, swing cylinder, boom cylinder 25, arm cylinder 26, and bucket cylinder 27 mentioned above). Figure 3 shows the configuration related to the slewing motor in the drive system of the electric excavator in this embodiment.

[0025] The drive system of this embodiment includes an electric motor 40, a hydraulic pump 41 and a pilot pump 42 driven by the electric motor 40, a slewing control valve 43 that controls the flow of pressurized oil (specifically, direction and flow rate) from the hydraulic pump 41 to the slewing motor 14, and a work operation device 44 that switches the slewing control valve 43. The work operation device 44 is mounted on the cab 29 of the slewing body 12, while the electric motor 40, hydraulic pump 41, pilot pump 42, and slewing control valve 43 are mounted on other parts of the slewing body 12 (see Figure 2 above).

[0026] The operating device 44 includes the operating lever 39 described above, a first pilot valve (not shown) that reduces the discharge pressure of the pilot pump 42 to generate pilot pressure according to the amount of leftward movement of the operating lever 39, and a second pilot valve (not shown) that reduces the discharge pressure of the pilot pump 42 to generate pilot pressure according to the amount of rightward movement of the operating lever 39.

[0027] When the operator operates the work lever 39 to the left, the pilot pressure generated by the first pilot valve according to the amount of operation is output to the pressure receiving section on one side of the swing control valve 43. This switches the swing control valve 43 to the left-hand switching position shown in the figure, and pressurized oil from the hydraulic pump 41 is supplied to the left-hand port of the swing motor 14 via the swing control valve 43, causing the swing motor 14 to rotate in one direction. As a result, the swing body 12 swings to the left (in other words, counterclockwise when viewed from above).

[0028] When the operator moves the work control lever 39 to the right, the pilot pressure generated by the second pilot valve according to the amount of operation is output to the pressure receiving part on the other side of the swing control valve 43. As a result, the swing control valve 43 is switched to the switching position on the right side of the figure, and pressurized oil from the hydraulic pump 41 is supplied to the port on the right side of the swing motor 14 via the swing control valve 43, causing the swing motor 14 to rotate in the opposite direction. Consequently, the swing body 12 swings to the right (in other words, clockwise when viewed from above).

[0029] One of the features of this embodiment is that a swivel lock valve 45A, which can be switched between a shut-off state and a communicative state, is provided in the oil passage between the first pilot valve of the work operating device 44 and the pressure receiving part on one side of the swivel control valve 43, and a swivel lock valve 45B, which can be switched between a shut-off state and a communicative state, is provided in the oil passage between the second pilot valve of the work operating device 44 and the pressure receiving part on the other side of the swivel control valve 43. The swivel lock valves 45A and 45B correspond to a swivel lock device that puts the swivel body described in the claims into a locked state that prohibits the swivel operation.

[0030] When the swivel lock valves 45A and 45B are in the closed state (locked state), the swivel control valve 43 is not switched regardless of the left-right movement of the work operation lever 39, and therefore the swivel motor 14 does not rotate. In other words, the swivel movement of the swivel body 12 is prohibited. On the other hand, when the swivel lock valves 45A and 45B are in the open state (unlocked state), the swivel control valve 43 is switched in response to the left-right movement of the work operation lever 39, and therefore the swivel motor 14 rotates. In other words, the swivel movement of the swivel body 12 is permitted.

[0031] The electric motor 40 is driven by power supplied from an external power source 1 via a power supply cable 2. Alternatively, it is driven by power from a battery 46 (see Figure 4, described later) that has been charged by power supplied from an external power source 1 via a power supply cable 2. The electrical system of the electric excavator configured in this way will be explained using Figure 4. Figure 4 is a block diagram showing the configuration of the electric excavator's electrical system in this embodiment, along with related equipment.

[0032] The electrical system of this embodiment includes a rectifier 47 that converts AC power supplied from an external power source 1 via a power supply cable 2 into DC power, an inverter 48 that controls the rotational speed of the electric motor 40, a switch 49 that switches the connections between the rectifier 47, the inverter 48, and the battery 46, and a controller 50 that controls the switch 49, the inverter 48, etc. The battery 46, rectifier 47, inverter 48, switch 49, and controller 50 are mounted on the slewing body 12 (see Figure 2 above).

[0033] Although not shown in the diagram, the controller 50 includes a processor that executes processing according to a program, and memory for storing programs and data. When the connection sensor 32 detects that the power supply cable 2 is connected to the power supply port 31, the controller 50 controls the changeover switch 49 to connect the rectifier 47 and the inverter 48. In this case, the electric motor 40 is driven by power supplied from the external power supply 1 via the power supply cable 2.

[0034] Alternatively, when the connection sensor 32 detects that the power supply cable 2 is connected to the power supply port 31, the controller 50 controls the changeover switch 49 to connect the rectifier 47 and the battery 46. This allows the battery 46 to be charged by the power supplied from the external power source 1 via the power supply cable 2. When the connection sensor 32 detects that the power supply cable 2 is not connected to the power supply port 31, the controller 50 controls the changeover switch 49 to connect the inverter 48 and the battery 46. In this case, the electric motor 40 is driven by the power from the battery 46.

[0035] One of the features of this embodiment is that when the connection sensor 32 detects that the power supply cable 2 is connected to the power supply port 31, the controller 50 calculates the position of the gripping portion 36 of the cable stand 33 (for example, in polar coordinates with the center of the traveling body 11 as the origin) based on the detection results of the swivel angle sensor 15 and the rotation angle sensor 37. Then, according to the calculated position of the gripping portion 36 of the cable stand 33, the controller 50 performs swivel lock control, controlling the swivel lock valves 45A and 45B.

[0036] The slewing lock control described above will be explained using Figure 5. Figure 5 is a flowchart showing the contents of the slewing lock control in this embodiment.

[0037] In step S1, the controller 50 determines, based on the detection result of the connection sensor 32, whether the power supply cable 2 is connected to the power supply port 31. If the power supply cable 2 is not connected to the power supply port 31, the process proceeds to step S2. In step S2, the controller 50 controls the slewing lock valves 45A and 45B to the unlocked state. This allows the slewing body 12 to slewing.

[0038] If the power supply cable 2 is connected to the power supply port 31, the process proceeds to step S3. In step S3, the controller 50 calculates the position of the gripping portion 36 of the cable stand 33 based on the detection results of the swivel angle sensor 15 and the rotation angle sensor 37. Then, the process proceeds to step S4, where it is determined whether the calculated position of the gripping portion 36 of the cable stand 33 is within a predetermined range D1. The predetermined range D1 is pre-set and stored in the controller 50, assuming that the external power supply 1 is located behind the vehicle 11, as shown in Figures 6A and 6B, and that the power supply cable 2 gripped by the gripping portion 36 of the cable stand 33 does not come into contact with the vehicle 11.

[0039] For example, as shown in Figure 6A, if the calculated position of the gripping portion 36 of the cable stand 33 is within a predetermined range D1, the process moves to step S2. In step S2, the controller 50 controls the swivel lock valves 45A and 45B to an unlocked state. This allows the swivel body 12 to swivel. On the other hand, as shown in Figure 6B, if the calculated position of the gripping portion 36 of the cable stand 33 is outside the predetermined range D1, the process moves to step S5. In step S5, the controller 50 controls the swivel lock valves 45A and 45B to a locked state. This prevents the swivel body 12 from swiveling.

[0040] As described above, the electric excavator of this embodiment can perform a slewing motion even when the power supply cable 2 is connected. However, if there is a possibility that the power supply cable 2, which is gripped by the gripping portion 36 of the cable stand 33, may come into contact with the traveling body 11 and be damaged, the slewing motion is prohibited. This helps to reduce damage to the power supply cable 2.

[0041] In the first embodiment, the case was described as one in which the external power supply 1 is located at the rear of the traveling body 11 and a predetermined range is fixed relative to the position of the gripping portion 36 of the cable stand 33. However, the invention is not limited to this. That is, the predetermined range set relative to the gripping portion 36 of the cable stand 33 may be changed depending on the arrangement of the external power supply 1. Such modifications will be explained using Figures 7, 8, 9A, and 9B. Parts equivalent to those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0042] The modified electric excavator in this example is equipped with an input device 51 located inside the cab 29, which allows input of the placement of the external power supply 1 relative to the vehicle body 11 (see Figure 7). The input device 51 includes, for example, a display that indicates whether to select the rear, left, or right side of the vehicle body 11 as the placement of the external power supply 1, and a button to select whether to select the rear, left, or right side of the vehicle body 11 as the placement of the external power supply 1.

[0043] The controller 50 stores predetermined ranges D1, D2, and D3 (see Figure 8) set relative to the position of the gripping portion 36 of the cable stand 33. As described above, predetermined range D1 is set in advance as a range in which the power supply cable 2 gripped by the gripping portion 36 of the cable stand 33 does not come into contact with the vehicle 11, assuming that the external power supply 1 is located on the rear side of the vehicle 11 (right side in Figure 8). Predetermined range D2 is set in advance as a range in which the power supply cable 2 gripped by the gripping portion 36 of the cable stand 33 does not come into contact with the vehicle 11, assuming that the external power supply 1 is located on the left side of the vehicle 11 (lower side in Figure 8). Predetermined range D3 is set in advance as a range in which the power supply cable 2 gripped by the gripping portion 36 of the cable stand 33 does not come into contact with the vehicle 11, assuming that the external power supply 1 is located on the right side of the vehicle 11 (upper side in Figure 8).

[0044] The controller 50 changes a predetermined range according to the placement of the external power supply 1 input by the input device 51. For example, as shown in Figures 9A and 9B, if the placement of the external power supply 1 input by the input device 51 is to the right of the traveling body 11, the range is changed to a predetermined range D3. Then, as shown in Figures 9A and 9B, if the position of the gripping portion 36 of the cable stand 33 falls outside the predetermined range D1, the swivel lock valves 45A and 45B are controlled to a locked state, thereby preventing the swivel body 12 from swiveling.

[0045] In this modified example, the same effects as in the first embodiment can be obtained.

[0046] A second embodiment of the present invention will be described with reference to the drawings. In this embodiment, parts equivalent to those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0047] Figure 10 is a diagram showing the configuration of the drive system of the electric excavator in this embodiment, specifically the configuration related to the travel motor. Figure 11 is a block diagram showing the configuration of the electrical system of the electric excavator in this embodiment, along with related equipment.

[0048] The drive unit of this embodiment includes a travel control valve 52A that controls the flow of pressurized oil (specifically, direction and flow rate) from the hydraulic pump 41 to the left travel motor 20A, a travel operating device 53A that switches the travel control valve 52A, a travel control valve 52B that controls the flow of pressurized oil (specifically, direction and flow rate) from the hydraulic pump 41 to the right travel motor 20B, and a travel operating device 53B that switches the travel control valve 52B. The travel operating devices 53A and 53B are mounted on the cab 29 of the slewing body 12, while the travel control valves 52A and 52B are mounted on other parts of the slewing body 12.

[0049] The driving control device 53A includes the driving control lever / pedal 38A described above, a third pilot valve (not shown) that reduces the discharge pressure of the pilot pump 42 to generate pilot pressure according to the amount of forward operation of the driving control lever / pedal 38A, and a fourth pilot valve (not shown) that reduces the discharge pressure of the pilot pump 42 to generate pilot pressure according to the amount of rearward operation of the driving control lever / pedal 38A.

[0050] The driving control device 53B includes the driving control lever / pedal 38B described above, a fifth pilot valve (not shown) that reduces the discharge pressure of the pilot pump 42 to generate pilot pressure according to the amount of forward operation of the driving control lever / pedal 38B, and a sixth pilot valve (not shown) that reduces the discharge pressure of the pilot pump 42 to generate pilot pressure according to the amount of rearward operation of the driving control lever / pedal 38B.

[0051] When the driver operates the driving lever / pedal 38A forward, a pilot pressure generated by the third pilot valve according to the amount of operation is output to the pressure receiving section on one side of the driving control valve 52A. This switches the driving control valve 52A to the left-hand switching position shown in the figure, and pressurized oil from the hydraulic pump 41 is supplied to the left-hand port of the driving motor 20A via the driving control valve 52A, causing the driving motor 20A to rotate forward. Simultaneously, when the driver operates the driving lever / pedal 38B forward, a pilot pressure generated by the fifth pilot valve according to the amount of operation is output to the pressure receiving section on one side of the driving control valve 52B. This switches the driving control valve 52B to the left-hand switching position shown in the figure, and pressurized oil from the hydraulic pump 41 is supplied to the left-hand port of the driving motor 20B via the driving control valve 52B, causing the driving motor 20B to rotate forward. As a result, the vehicle 11 moves forward.

[0052] When the driver operates the driving lever / pedal 38A to the rear, the pilot pressure generated by the fourth pilot valve according to the amount of operation is output to the pressure receiving section on the other side of the driving control valve 52A. This switches the driving control valve 52A to the switching position on the right in the figure, and pressurized oil from the hydraulic pump 41 is supplied to the port on the right in the figure of the driving motor 20A via the driving control valve 52A, causing the driving motor 20A to rotate in the rear direction. At the same time, when the driver operates the driving lever / pedal 38B to the rear, the pilot pressure generated by the sixth pilot valve according to the amount of operation is output to the pressure receiving section on the other side of the driving control valve 52B. This switches the driving control valve 52B to the switching position on the right in the figure, and pressurized oil from the hydraulic pump 41 is supplied to the port on the right in the figure of the driving motor 20B via the driving control valve 52B, causing the driving motor 20B to rotate in the rear direction. As a result, the vehicle 11 moves in reverse.

[0053] One of the features of this embodiment is that a forward lock valve 54A, which can be switched between a shut-off state and a communicative state, is provided in the oil passage between the third pilot valve of the travel operating device 53A and the pressure receiving portion on one side of the travel control valve 52A, and a forward lock valve 54B, which can be switched between a shut-off state and a communicative state, is provided in the oil passage between the fifth pilot valve of the travel operating device 53B and the pressure receiving portion on one side of the travel control valve 52B. The forward lock valves 54A and 54B correspond to a forward lock device that puts the vehicle into a locked state that prohibits forward movement of the vehicle as described in the claims.

[0054] When the forward lock valves 54A and 54B are in the closed state (locked state), the drive control valves 52A and 52B cannot be switched regardless of the operation of the front drive levers and pedals 38A and 38B, so the drive motors 20A and 20B do not rotate forward. In other words, the forward movement of the vehicle 11 is prohibited. On the other hand, when the forward lock valves 54A and 54B are in the open state (unlocked state), the drive control valves 52A and 52B are switched in response to the operation of the front drive levers and pedals 38A and 38B, so the drive motors 20A and 20B rotate forward. In other words, the forward movement of the vehicle 11 is permitted.

[0055] One of the features of this embodiment is that a reverse lock valve 55A, which can be switched between a shut-off state and a communicative state, is provided in the oil passage between the fourth pilot valve of the driving control device 53A and the pressure receiving part on the other side of the driving control valve 52A, and a reverse lock valve 55B, which can be switched between a shut-off state and a communicative state, is provided in the oil passage between the sixth pilot valve of the driving control device 53B and the pressure receiving part on the other side of the driving control valve 52B. The reverse lock valves 55A and 55B correspond to a reverse lock device that puts the vehicle into a locked state that prohibits reverse movement of the vehicle as described in the claims.

[0056] When the reverse lock valves 55A and 55B are in the closed state (locked state), the drive control valves 52A and 52B cannot be switched regardless of the operation of the rear drive levers and pedals 38A and 38B, so the drive motors 20A and 20B do not rotate in the reverse direction. In other words, the reverse movement of the vehicle 11 is prohibited. On the other hand, when the reverse lock valves 55A and 55B are in the open state (unlocked state), the drive control valves 52A and 52B are switched in response to the operation of the rear drive levers and pedals 38A and 38B, so the drive motors 20A and 20B rotate in the reverse direction. In other words, the reverse movement of the vehicle 11 is permitted.

[0057] One of the features of this embodiment is that when the connection sensor 32 detects that the power supply cable 2 is connected to the power supply port 31, the controller 50 calculates the position of the gripping portion 36 of the cable stand 33 (for example, in polar coordinates with the center of the traveling body 11 as the origin) based on the detection results of the swivel angle sensor 15 and the rotation angle sensor 37. Then, according to the calculated position of the gripping portion 36 of the cable stand 33, it performs travel lock control, controlling the forward lock valves 54A, 54B and the reverse lock valves 55A, 55B.

[0058] The aforementioned vehicle lock control will be explained using Figure 12. Figure 12 is a flowchart showing the contents of the vehicle lock control in this embodiment.

[0059] In step S1, the controller 50 determines, based on the detection result of the connection sensor 32, whether the power supply cable 2 is connected to the power supply port 31. If the power supply cable 2 is not connected to the power supply port 31, the process proceeds to step S6. In step S6, the controller 50 controls the forward lock valves 54A, 54B and the reverse lock valves 55A, 55B to the unlocked state. This allows the vehicle 11 to move forward and backward.

[0060] If the power supply cable 2 is connected to the power supply port 31, the process proceeds to step S3. In step S3, the controller 50 calculates the position of the gripping portion 36 of the cable stand 33 based on the detection results of the swivel angle sensor 15 and the rotation angle sensor 37. Then, the process proceeds to step S7, where it is determined whether the calculated position of the gripping portion 36 of the cable stand 33 is within the first range E1. The first range E1 is pre-set and stored in the controller 50, assuming that the external power supply 1 is located behind the vehicle 11, as shown in Figure 13A, and represents the range in which the power supply cable 2, gripped by the gripping portion 36 of the cable stand 33, may be stepped on by the forward movement of the vehicle 11.

[0061] For example, as shown in Figure 13A, if the calculated position of the gripping portion 36 of the cable stand 33 is not within the first range E1, the process moves to step S8. In step S8, the controller 50 controls the forward lock valves 54A and 54B to the unlocked state. This allows the vehicle 11 to move forward. On the other hand, as shown in Figure 13B, if the calculated position of the gripping portion 36 of the cable stand 33 is within the first range E1, the process moves to step S9. In step S9, the controller 50 controls the forward lock valves 54A and 54B to the locked state. This prohibits the vehicle 11 from moving forward.

[0062] Subsequently, the process proceeds to step S10, where the controller 50 determines whether the calculated position of the gripping portion 36 of the cable stand 33 is within the second range F1. The second range F1 is pre-set and stored in the controller 50 as the range in which the power supply cable 2, gripped by the gripping portion 36 of the cable stand 33, may be run over by the reversing of the vehicle 11, assuming that the external power supply 1 is located on the rear side of the vehicle 11, as shown in Figure 13A. In this embodiment, the second range F1 is 360 degrees.

[0063] If the calculated position of the gripping portion 36 of the cable stand 33 is not within the second range (however, this is not possible in the second range F1 of this embodiment, but is possible in the second range F2 of the modified example described later), the process proceeds to step S11. In step S11, the controller 50 controls the reverse lock valves 55A and 55B to the unlocked state. This allows the vehicle 11 to move in reverse. On the other hand, as shown in Figures 13A and 13B, if the calculated position of the gripping portion 36 of the cable stand 33 is within the second range F1, the process proceeds to step S12. In step S12, the controller 50 controls the reverse lock valves 55A and 55B to the locked state. This prohibits the vehicle 11 from moving in reverse.

[0064] As described above, in this embodiment, the electric shovel can perform travel operations (forward movement only in this embodiment) even when the power supply cable 2 is connected. However, if there is a possibility that the power supply cable 2, which is gripped by the gripping portion 36 of the cable stand 33, may be run over by the movement of the traveling body 11, travel operations are prohibited. This helps to reduce damage to the power supply cable 2.

[0065] In the second embodiment, the case was described as one in which the external power supply 1 is located on the rear side of the traveling body 11 and the first and second ranges set with respect to the gripping portion 36 of the cable stand 33 are fixed, but the embodiment is not limited to this. That is, the first and second ranges set with respect to the gripping portion 36 of the cable stand 33 may be changed depending on the arrangement of the external power supply 1. Such modifications will be explained using Figures 14, 15, 16A, and 16B. Parts equivalent to those in the second embodiment are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0066] This modified electric excavator is equipped with an input device 51 located inside the cab 29, which can input the configuration of the external power supply 1 relative to the traveling body 11 (see Figure 14).

[0067] The controller 50 further stores the first range E2 and the second range F2 (see Figure 15) set relative to the position of the gripping portion 36 of the cable stand 33. The first range E2 is pre-set as the range in which the power supply cable 2, gripped by the gripping portion 36 of the cable stand 33, may be run over by the forward movement of the vehicle, assuming that the external power supply 1 is located on the left side (lower side in Figure 15) or right side (upper side in Figure 15) of the vehicle 11. The second range F2 is pre-set as the range in which the power supply cable 2, gripped by the gripping portion 36 of the cable stand 33, may be run over by the reverse movement of the vehicle, assuming that the external power supply 1 is located on the left side or right side of the vehicle 11.

[0068] The controller 50 changes the first and second ranges according to the arrangement of the external power supply 1 input by the input device 51. For example, as shown in Figures 16A and 16B, if the arrangement of the external power supply 1 input by the input device 51 is to the right of the vehicle 11, the ranges are changed to the first range E2 and the second range F2. For example, as shown in Figure 16A, if the position of the gripping portion 36 of the cable stand 33 is in the first range E2, the forward lock valves 54A and 54B are controlled to the locked state to prevent the vehicle 11 from moving forward. For example, as shown in Figure 16B, if the position of the gripping portion 36 of the cable stand 33 is in the second range F2, the reverse lock valves 55A and 55B are controlled to the locked state to prevent the vehicle 11 from moving backward.

[0069] In this modified example, the same effects as in the second embodiment can be obtained.

[0070] In the first embodiment and its modified form, and the second embodiment and its modified form, the operating device was described as having a pilot valve that reduces the discharge pressure of the pilot pump 42 according to the amount of operation of the operating member to generate pilot pressure, and outputs the generated pilot pressure to the pressure receiving section of the control valve, but it is not limited to this. The operating device may also have a potentiometer that detects the amount of operation of the operating member and outputs the detection signal to the controller 50. In this modified form, the controller 50 generates a drive signal corresponding to the detection signal of the operating device and outputs the generated drive signal to the electromagnetic proportional valve. The electromagnetic proportional valve reduces the discharge pressure of the pilot pump 42 according to the drive signal to generate pilot pressure, and outputs the generated pilot pressure to the pressure receiving section of the control valve. The controller 50 switches a lock valve provided in the oil passage between the electromagnetic proportional valve and the pressure receiving section of the control valve between a closed state and a connected state, or switches the activation and deactivation of the detection signal output from the operating device. Swing lock control or travel lock control may be performed by doing so. The same effects as described above can be obtained in such modified forms as well.

[0071] In the first embodiment and its modifications, the case of performing slewing lock control was used as an example, and in the second embodiment and its modifications, the case of performing travel lock control was used as an example; however, these may be combined.

[0072] In the above description, an electric excavator was used as an example of the application of the present invention, but the invention is not limited to this, and may be applied to other electric construction machinery. [Explanation of Symbols]

[0073] 1 External power supply 2 Power supply cable 11. Running body 12. Rotating body 13 Working equipment 15 Swivel Angle Sensor 31 Power supply port 32 connected sensors 33 Cable Stands 36 Gripping part 37-degree angle sensor 45A, 45B Swivel lock valve (Swivel lock device) 50 Controllers 51 Input device 54A, 54B Forward locking valve (forward locking device) 55A, 55B Reverse Lock Valve (Reverse Lock Device)

Claims

1. An electric construction machine comprising a traveling body, a rotating body rotatably mounted above the traveling body, a working device connected to the rotating body, a power supply port located on the rotating body to which a power supply cable from an external power source is connected, and a cable stand located on the rotating body having a gripping portion for gripping the power supply cable, the gripping portion configured to be rotatable around a vertical axis, A connection sensor that detects the state in which the power supply cable is connected to the power supply port, A slewing angle sensor for detecting the slewing angle of the slewing body, A rotation angle sensor for detecting the rotation angle of the gripping portion of the cable stand, A slewing lock device that locks the slewing body to a state where its slewing motion is prohibited, The system includes a controller that controls the aforementioned swivel locking device, The aforementioned controller, An electric construction machine characterized in that, when the connection sensor detects that the power supply cable is connected to the power supply port, the position of the gripping portion of the cable stand is calculated based on the detection results of the swivel angle sensor and the rotation angle sensor, and when the calculated position of the gripping portion of the cable stand is outside a predetermined range in which the power supply cable gripped by the gripping portion of the cable stand does not come into contact with the traveling body, the swivel locking device is controlled to a locked state.

2. In the electric construction machine according to claim 1, The vehicle is equipped with an input device that can input the arrangement of the external power supply relative to the vehicle, The controller is characterized by changing the predetermined range according to the arrangement of the external power supply input by the input device.

3. An electric construction machine comprising a traveling body, a rotating body rotatably mounted above the traveling body, a working device connected to the rotating body, a power supply port located on the rotating body to which a power supply cable from an external power source is connected, and a cable stand located on the rotating body having a gripping portion for gripping the power supply cable, the gripping portion configured to be rotatable around a vertical axis, A connection sensor that detects the state in which the power supply cable is connected to the power supply port, A slewing angle sensor for detecting the slewing angle of the slewing body, A rotation angle sensor for detecting the rotation angle of the gripping portion of the cable stand, A forward locking device that locks the vehicle to prevent it from moving forward, A reverse locking device that locks the vehicle to prevent it from moving in reverse, The system includes a controller that controls the forward locking device and the reverse locking device, The aforementioned controller, If the connection sensor detects that the power supply cable is connected to the power supply port, the position of the gripping portion of the cable stand is calculated based on the detection results of the swivel angle sensor and the rotation angle sensor. When the calculated position of the gripping portion of the cable stand is within a first range in which the power supply cable gripped by the gripping portion of the cable stand may be stepped on by the forward movement of the vehicle, the forward locking device is controlled to a locked state. An electric construction machine characterized in that, when the calculated position of the gripping portion of the cable stand is within a second range in which the power supply cable gripped by the gripping portion of the cable stand may be trampled by the reversing of the vehicle, the reverse locking device is controlled to a locked state.

4. In the electric construction machine according to claim 3, The vehicle is equipped with an input device that can input the arrangement of the external power supply relative to the vehicle, The controller is characterized by changing the first range and the second range according to the arrangement of the external power supply input by the input device.

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