Electric construction machinery

Abstract

To provide an electric construction machine which can suppress damage of a feeder cable.SOLUTION: An electric shovel includes: a turning body 12 turnably provided on an upper side of a traveling body 11; a cable guide 29 having a gripping part 33 for gripping a feeder cable 2 connected to the turning body 12 from an external power source 1, and provided on the turning body 12 so as to be rotatable around a vertical axis of the turning body 12; a turning angle sensor 16 for detecting a turning angle of the turning body 12; a rotation angle sensor 34 for detecting a rotation angle of the cable guide 29; a guide motor 36 for rotating the cable guide 29; and a controller 47 for controlling the guide motor 36 on the basis of detection results of the turning angle sensor 16 and the rotation angle sensor 34.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an electric construction machine to which a power supply cable can be connected.

Background Art

[0002] An electric excavator, which is one of the electric construction machines, 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 the pressure oil discharged from the hydraulic pump. In the electric excavator, there is one configured such that 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 the 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 the power supply cable is connected, the operation of the excavator can be performed, and it includes a cable guide (cable stand) for suppressing damage to the power supply cable. The cable guide has a gripping portion for gripping the power supply cable, and is provided on the rear side of the revolving body (in other words, the side opposite to the working device) so as to be rotatable about the vertical axis of the revolving body. When the revolving body revolves, the cable guide rotates in the opposite direction due to the action of the tension of 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] As described above, the cable guide in Patent Document 2 is configured to rotate due to the tension of the power supply cable when the rotating body rotates. Therefore, if there is no tension in the power supply cable, the cable guide will not rotate relative to the rotating body (i.e., it will rotate together with the rotating body), and the power supply cable held by the cable guide may come into contact with the traveling body and be damaged.

[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 prevent damage to power supply cables. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides an electric construction machine comprising: a traveling body; a slewing body rotatably mounted above the traveling body; and a cable guide mounted on the slewing body so as to be rotatable around the vertical axis of the slewing body, having a gripping portion for gripping a power supply cable connected to the slewing body from an external power source, the electric construction machine further comprising: a slewing angle sensor for detecting the slewing angle of the slewing body; a rotation angle sensor for detecting the rotation angle of the cable guide; a guide motor for rotating the cable guide; and a controller for controlling the guide motor based on the detection results of the slewing angle sensor and the rotation angle sensor. [Effects of the Invention]

[0009] According to the present invention, damage to the power supply cable can be prevented. [Brief explanation of the drawing]

[0010] [Figure 1]This is a side view showing the structure of an electric excavator in one embodiment of the present invention. [Figure 2] This is a top view showing the structure of the rotating body of an electric excavator in one embodiment of the present invention. [Figure 3] This is an exploded perspective view showing the structure of a cable guide for an electric excavator in one embodiment of the present invention. [Figure 4] This diagram shows the configuration of the swing motor in the drive system of an electric excavator according to one embodiment of the present invention. [Figure 5] This diagram shows the electrical system configuration of an electric excavator in one embodiment of the present invention. [Figure 6] This is a flowchart illustrating the control mechanisms of the controller in a modified version of the device. [Figure 7] This is a top view showing a specific example of the operation of an electric shovel in a comparative example of the present invention. [Figure 8] This is a top view illustrating a specific example of the operation of an electric excavator in one embodiment of the present invention. [Figure 9] This is a top view showing a specific example of the operation of an electric shovel in a comparative example of the present invention. [Figure 10] This is a top view illustrating a specific example of the operation of an electric shovel in a modified version of the present invention. [Modes for carrying out the invention]

[0011] One embodiment of the present invention will be described with reference to the drawings.

[0012] Figure 1 is a side view showing the structure of the electric excavator in this embodiment. Figure 2 is a top view showing the structure of the slewing body of the electric excavator in this embodiment. Figure 3 is an exploded perspective view showing the structure of the cable guide of the electric excavator in this embodiment. Note that in Figure 2, a part of the outer cover of the slewing body is removed to show the equipment mounted on the slewing body. Also, although the gripping part of the cable guide is shown in Figure 1, it is omitted in Figures 2 and 3.

[0013] The electric excavator of this 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 (the left side in FIG. 1) of the revolving body 12. The traveling body 11 travels by the rotation of left and right traveling motors 14. The revolving body 12 revolves by the rotation of a revolving motor 15, and its revolving angle is detected by a revolving angle sensor 16 (see FIG. 5 described later).

[0014] The working device 13 includes, for example, a swing post 17 connected to the front side of the revolving body 12 so as to be rotatable in the left - right direction, a boom 18 connected to the upper side of the swing post 17 so as to be rotatable in the up - down direction, an arm 19 connected to the tip side of the boom 18 so as to be rotatable in the up - down direction, and a bucket 20 connected to the tip side of the arm 19 so as to be rotatable in the up - down direction. The swing post 17 rotates by the extension and contraction of a swing cylinder (not shown), the boom 18 rotates by the extension and contraction of a boom cylinder 21, the arm 19 rotates by the extension and contraction of an arm cylinder 22, and the bucket 20 rotates by the extension and contraction of a bucket cylinder 23.

[0015] The revolving body 12 includes a revolving frame 24 forming a lower basic structure, a cab (driver's cab) 25 provided on the left side of the revolving frame 24 (the front side with respect to the paper surface of FIG. 1, the lower side of FIG. 2), and a counterweight 26 provided on the rear side of the revolving frame 24 (the right side of FIGS. 1 and 2).

[0016] Further, the revolving body 12 includes a cable connector 27 disposed above the counterweight 26 and capable of connecting a power supply cable 2 from an external power source 1 (for example, a commercial power source), a connection sensor 28 for detecting a state in which the power supply cable 2 is connected to the cable connector 27, and a cable guide 29 provided above the counterweight 26 for guiding the power supply cable 2.

[0017] The cable guide 29 includes a pedestal 30 fixed to the counterweight 26, a rotary shaft 31 supported by the pedestal 30 via a bearing (such as a bush, not shown) and rotatable about the vertical axis of the swivel body 12, a guide arm 32 extending horizontally from the rotary shaft 31, and a gripping portion 33 (such as a clamp) provided at the tip side of the guide arm 32 for gripping the power supply cable 2.

[0018] Further, as a feature of the present embodiment, the cable guide 29 includes a rotation angle sensor 34 (see FIG. 5 described later) for detecting the rotation angle of the guide arm 32 with respect to a predetermined direction (for example, the rear direction) of the swivel body 12, and a guide motor 36 connected to the rotary shaft 31 via a connecting shaft 35 for rotating the guide arm 32. The rotation range of the guide arm 32 is limited by a mechanical method or / and a control method for avoiding contact between the guide arm 32 and the cab 25, etc.

[0019] The electric excavator includes a drive device for driving a plurality of hydraulic actuators (specifically, the traveling motor 14, the slewing motor 15, the swing cylinder, the boom cylinder 21, the arm cylinder 22, and the bucket cylinder 23 described above). FIG. 3 is a diagram showing the configuration related to the slewing motor among the configurations of the drive device of the electric excavator in the present embodiment.

[0020] The drive device of the present embodiment includes an electric motor 37, a hydraulic pump 38 and a pilot pump 39 driven by the electric motor 37, a control valve 40 for controlling the flow of pressure oil (specifically, the direction and flow rate) from the hydraulic pump 38 to the slewing motor 15, and an operating device 41 for switching the control valve 40. The operating device 41 is mounted on the cab 25 of the swivel body 12, and the electric motor 37, the hydraulic pump 38, the pilot pump 39, and the control valve 40 are mounted on other parts of the swivel body 12 (see FIG. 2 described above).

[0021] The operating device 41 includes an operating lever 42 that can be operated by the operator, a first pilot valve (not shown) that reduces the discharge pressure of the pilot pump 39 to generate pilot pressure according to the amount of operation of one side of the operating lever 42, and a second pilot valve (not shown) that reduces the discharge pressure of the pilot pump 39 to generate pilot pressure according to the amount of operation of the other side of the operating lever 42.

[0022] When the operator operates the control lever 42 to one side, 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 control valve 40. This switches the control valve 40 to the left-hand switching position shown in the figure, and pressurized oil from the hydraulic pump 38 is supplied to the left-hand port of the swing motor 15 via the control valve 40, causing the swing motor 15 to rotate in one direction. As a result, the swing body 12 swings to the left (in other words, counterclockwise when viewed from above).

[0023] When the operator moves the control lever 42 to the other side, the pilot pressure generated by the second pilot valve according to the amount of movement is output to the pressure receiving part on the other side of the control valve 40. As a result, the control valve 40 is switched to the switching position on the right side of the figure, and pressurized oil from the hydraulic pump 38 is supplied to the port on the right side of the figure of the swing motor 15 via the control valve 40, causing the swing motor 15 to rotate in the opposite direction. Consequently, the swing body 12 swings to the right (in other words, clockwise when viewed from above).

[0024] The electric motor 37 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 43 (see Figure 5, 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 5. Figure 5 is a block diagram showing the configuration of the electric excavator's electrical system in this embodiment, along with related equipment.

[0025] The electrical system of this embodiment includes a rectifier 44 that converts AC power supplied from an external power source 1 via a power supply cable 2 into DC power, an inverter 45 that controls the rotational speed of the electric motor 37, a switch 46 that switches the connection between the rectifier 44, the inverter 45, and the battery 43, and a controller 47 that controls the switch 46, the inverter 45, etc. The battery 43, rectifier 44, inverter 45, switch 46, and controller 47 are mounted on the slewing body 12 (see Figure 2 above).

[0026] Although not shown, the controller 47 includes a processor that executes processing according to a program, and memory for storing programs and data. When the connection sensor 28 detects that the power supply cable 2 is connected to the cable connector 27, the controller 47 controls the switch 46 to connect the rectifier 44 and the inverter 45. In this case, the electric motor 37 is driven by power supplied from the external power supply 1 via the power supply cable 2.

[0027] Alternatively, when the controller 47 detects with the connection sensor 28 that the power supply cable 2 is connected to the cable connector 27, it controls the changeover switch 46 to connect the rectifier 44 and the battery 43. This allows the battery 43 to be charged by the power supplied from the external power source 1 via the power supply cable 2. When the controller 47 detects with the connection sensor 28 that the power supply cable 2 is not connected to the cable connector 27, it controls the changeover switch 46 to connect the inverter 45 and the battery 43. In this case, the electric motor 37 is driven by the power from the battery 43.

[0028] A key feature of this embodiment is that the controller 47 controls the guide motor 36 based on the detection results of the swivel angle sensor 16 and the rotation angle sensor 34. The control details of this controller 47 will be explained using Figure 6. Figure 6 is a flowchart showing the control details of the controller in this embodiment.

[0029] In step S1, the controller 47 determines, based on the detection result of the connection sensor 28, whether the power supply cable 2 is connected to the cable connector 27. If the power supply cable 2 is connected to the cable connector 27, the process proceeds to step S2. In step S2, the controller 47 calculates the rotation angle of the guide arm 32 with respect to a predetermined direction (for example, the rearward direction) of the traveling body 11, based on the detection results of the swivel angle sensor 16 and the rotation angle sensor 34.

[0030] Next, the process proceeds to step S3, where the controller 47 determines whether the calculated rotation angle does not match the set value. This set value is set to zero, for example, assuming that the external power supply 1 is located behind the vehicle 11, with respect to the rear direction of the vehicle 11. If the calculated rotation angle does not match the set value, the process proceeds to step S4. In step S4, the controller 47 controls the guide motor 36 so that the calculated rotation angle matches the set value.

[0031] The effects of this embodiment will be explained using comparative examples. Figure 7 is a top view showing a specific example of the operation of an electric excavator in a comparative example. Figure 8 is a top view showing a specific example of the operation of an electric excavator in this embodiment.

[0032] The cable guide 129 of the comparative example electric excavator does not have a guide motor 36 and is configured to rotate due to the tension of the power supply cable 2 when the slewing body 12 rotates. Therefore, as shown in Figure 7, if the tension of the power supply cable 2 is not acting, the cable guide 129 (specifically, the guide arm 132) will not rotate relative to the slewing body 12 (i.e., it will rotate together with the slewing body 12), and the power supply cable 2 gripped by the cable guide 129 may come into contact with the traveling body 11 and be damaged.

[0033] On the other hand, the cable guide 29 of the electric excavator in this embodiment is configured to rotate by a guide motor 36. Based on the detection results of the slewing angle sensor 16 and the rotation angle sensor 34, the controller 47 calculates the rotation angle of the cable guide 29 (specifically, the rotation angle of the guide arm 32) with respect to a predetermined direction of the traveling body 11, and controls the guide motor 36 so that the calculated rotation angle becomes a set value. As a result, as shown in Figure 8, when the slewing body 12 rotates, the cable guide 29 (specifically, the guide arm 32) rotates relative to the slewing body 12, and the power supply cable 2 gripped by the cable guide 29 does not come into contact with the traveling body 11. Therefore, damage to the power supply cable 2 can be prevented.

[0034] In the first embodiment, the example described was one in which the set value for the rotation angle of the cable guide 29 relative to a predetermined direction of the traveling body 11 is fixed, but the invention is not limited to this. That is, the electric excavator may be equipped with a setting device 48 that varies the set value for the rotation angle of the cable guide 29 relative to a predetermined direction of the traveling body 11, as shown by the dotted line in Figure 5.

[0035] The setting device 48 has, for example, a switch that can be operated by the driver, and is configured to allow the driver to instruct the current rotation angle of the cable guide 29 (more specifically, the current rotation angle of the guide arm 32) relative to a predetermined direction of the traveling body 11 to be set as a set value. The controller 47, in accordance with the instructions from the setting device 48, calculates the rotation angle of the cable guide 29 relative to the predetermined direction of the traveling body 11 based on the detection results of the swivel angle sensor 16 and the rotation angle sensor 34, and sets the calculated rotation angle as a set value. This makes it possible to vary the set value according to the arrangement of the external power supply 1.

[0036] In this modified example, the same effects as in the above embodiment can be obtained. Taking the case where the above-mentioned setting value is set to 90 degrees as an example, the effects of this modified example will be explained using the comparative example. Figure 9 is a top view showing a specific example of the operation of the electric shovel in the comparative example. Figure 10 is a top view showing a specific example of the operation of the electric shovel in this modified example.

[0037] The cable guide 129 of the comparative example electric excavator does not have a guide motor 36 and is configured to rotate due to the tension of the power supply cable 2 when the slewing body 12 rotates. Therefore, as shown in Figure 9, if the tension of the power supply cable 2 is not acting, the cable guide 129 (specifically, the guide arm 132) will not rotate relative to the slewing body 12 (i.e., it will rotate together with the slewing body 12), and the power supply cable 2 held by the cable guide 129 may come into contact with the traveling body 11 and be damaged.

[0038] On the other hand, the cable guide 29 of the electric excavator in this modified example is configured to rotate by a guide motor 36. Based on the detection results of the slewing angle sensor 16 and the rotation angle sensor 34, the controller 47 calculates the rotation angle of the cable guide 29 (specifically, the rotation angle of the guide arm 32) with respect to a predetermined direction of the traveling body 11, and controls the guide motor 36 so that the calculated rotation angle becomes a set value. Therefore, as shown in Figure 10, when the slewing body 12 rotates, the cable guide 29 (specifically, the guide arm 32) rotates, and the power supply cable 2 gripped by the cable guide 29 does not come into contact with the traveling body 11. Thus, damage to the power supply cable 2 can be prevented.

[0039] 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]

[0040] 1 External power supply 2 Power supply cable 11. Running body 12. Rotating body 16 Swivel Angle Sensor 27 Cable Connectors 28 connected sensors 29 Cable Guide 32 Guide Arms 33 Gripping part 34-degree angle sensor 36 Guide motor 47 Controllers 48 Setting device

Claims

1. An electric construction machine comprising a traveling body, a rotating body rotatably mounted above the traveling body, and a cable guide mounted on the rotating body so as to be rotatable around the vertical axis of the rotating body, having a gripping portion for gripping a power supply cable connected to the rotating body from an external power source, A slewing angle sensor for detecting the slewing angle of the slewing body, A rotation angle sensor for detecting the rotation angle of the cable guide, A guide motor that rotates the cable guide, An electric construction machine characterized by comprising a controller that controls the guide motor based on the detection results of the swivel angle sensor and the rotation angle sensor.

2. In the electric construction machine according to claim 1, The rotation angle sensor detects the rotation angle of the cable guide with respect to a predetermined direction of the rotating body, The controller is characterized in that it calculates the rotation angle of the cable guide with respect to a predetermined direction of the traveling body based on the detection results of the swivel angle sensor and the rotation angle sensor, and controls the guide motor so that the calculated rotation angle becomes a set value.

3. In the electric construction machine according to claim 2, The cable guide has a guide arm that extends horizontally and is rotated around a vertical axis by the guide motor, The gripping portion is provided on the tip side of the guide arm, The rotation angle sensor detects the rotation angle of the guide arm with respect to a predetermined direction of the rotating body, The controller is characterized in that it calculates the rotation angle of the guide arm with respect to a predetermined direction of the traveling body based on the detection results of the swivel angle sensor and the rotation angle sensor, and controls the guide motor so that the calculated rotation angle becomes a set value.

4. In the electric construction machine according to claim 1, A cable connector is provided on the rotating body to which the power supply cable is connected, The system further includes a connection sensor that detects the state in which the power supply cable is connected to the cable connector, The electric construction machine is characterized in that the controller controls the guide motor based on the detection results of the swivel angle sensor and the rotation angle sensor when the connection sensor detects that the power supply cable is connected to the cable connector.

5. In the electric construction machine according to claim 2, An electric construction machine characterized by being equipped with a setting device that varies the aforementioned set value.

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