Electric construction machine

Abstract

This electric construction machine 1 has a lower travel body 2 that includes a right travel device 21 and a left travel device 22 that are provided as a right / left pair and move forward / backward independently of each other. The electric construction machine 1 is driven by an external power supply that is connected by a cable 8. The electric construction machine 1 has: a cable reel device 6 that is provided to a rear end part that is between the right travel device 21 and the left travel device 22 of the lower travel body 2, accommodates the cable 8 in a wound state, winds the cable 8 up by forward rotation, and feeds the cable 8 out by backward rotation; and a control device 14 that controls the rotation direction of the cable reel device 6 in accordance with the movement state of the lower travel body 2.

Description

electric construction machinery

[0001] The present invention relates to an electric construction machine equipped with a cable reel device.

[0002] One method of powering electric construction machinery (e.g., electric hydraulic excavators) involves connecting cables from equipment such as substations and disconnectors to a power supply terminal box or a cable reel device with an automatic retraction function mounted on the rear of the truck frame. The cable is routed to the rear of the vehicle to prevent it from being stepped on. With a power supply terminal box, excess cable is routed around the vehicle body, increasing the risk of the cable being stepped on when the vehicle is traveling or the undercarriage turns. With a cable reel device, the cable is constantly retracted; it unwinds when the vehicle moves forward and retracts when the vehicle moves backward, keeping the cable taut at all times. This eliminates excess cable around the vehicle body, reducing the risk of the cable being stepped on. However, with a cable reel device that constantly retracts the cable, the risk of the cable being stepped on remains high depending on the relative position of the vehicle body and the cable when the undercarriage turns or reverses.

[0003] Regarding the above situation, Patent Document 1 discloses a technology for reliably preventing accidents such as cable breakage by automatically stopping the vehicle when the cable reaches its winding or unwinding limit, thereby preventing the cable from being wound or unwound beyond the respective limits.

[0004] Special Publication No. 49-030649

[0005] The technology proposed in Patent Document 1 can detect the winding and unwinding limits of the cable, but cannot detect the cable when the cable is not at its winding or unwinding limit, such as when the undercarriage turns or when the vehicle is reversing to turn left or right. Furthermore, while it is possible to restrict the vehicle's travel after detecting the winding and unwinding limits of the cable, depending on the cable's location, manual intervention is required to move the cable, which poses risks for people approaching the vehicle and moving the high-voltage cable, and also increases downtime for the vehicle.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an electric construction machine that prevents the contact points of the undercarriage and the cable from coming close to each other when the undercarriage turns or when reversing to turn left or right, thereby contributing to reducing vehicle downtime.

[0007] In order to achieve the above object, the electric construction machine of the present invention has a lower traveling body including a pair of traveling devices provided on the left and right sides that move forward and backward independently of each other, and is driven by being connected to an external power source via a cable.The electric construction machine has a cable reel device provided at the rear end between the pair of traveling devices on the lower traveling body, which winds and stores the cable, and the cable is wound by forward drive and unwound by reverse drive, and a control device that controls the rotation direction of the cable reel device depending on the operating state of the lower traveling body.

[0008] According to the present invention, by paying out the cable when the undercarriage turns or when reversing to turn left or right, it is possible to separate the portion of the cable that is in contact with the ground from the vehicle body. This makes it possible to prevent the cable from coming into contact with the undercarriage or being stepped on. Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. In addition to the above, problems, configurations, and effects will become apparent from the following description of the embodiments.

[0009] 1 is a diagram illustrating a vehicle body layout of an electric construction machine according to an embodiment; a diagram illustrating an example of the configuration of cable wiring from a power plant to an electric hydraulic excavator; a block diagram illustrating the peripheral hardware configuration of a control device (controller) according to an embodiment; a functional block diagram illustrating the functional configuration of a control device (controller) according to an embodiment; a diagram for explaining a situation in which a cable may be trampled on while a construction machine is in operation; a diagram for explaining whether or not cable trampling occurs depending on the ground position of the cable; a table for explaining rotation control of a cable reel device according to an embodiment; a flowchart showing processing executed by a control device (controller) in an embodiment; a table for explaining rotation control of a cable reel device using a GPS signal according to an embodiment; a diagram for explaining a situation in which the turning direction for reeling out the cable is determined by the positional relationship between a disconnector and the vehicle body; a diagram for explaining a situation in which the turning direction for reeling out the cable is determined by the positional relationship between a disconnector and the vehicle body; a diagram for explaining the relationship between the input direction of a travel lever and time counting according to an embodiment; a vehicle body layout of an electric construction machine according to another embodiment; a diagram for explaining the maximum reeling length of the cable.

[0010] The following description of the embodiments will be made with reference to the drawings. In the following embodiments, an electric hydraulic excavator will be used as an example of an electric construction machine, but the electric construction machine is not limited to this, and the present invention can be applied to other vehicles as long as the electric construction machine has a pair of left and right traveling devices that can move forward and backward independently of each other.

[0011] In this specification, "turning" refers to the undercarriage of an electric construction machine rotating left and right on the spot or while moving forward and backward to change its direction of travel. For example, it refers to rotating the left and right travel devices of the undercarriage on the spot by moving forward and backward, respectively, steering only one of the left and right travel devices by moving forward or backward, or steering one of the left and right travel devices with a difference in rotation. In other words, turning does not refer to a specific operation such as a U-turn. Furthermore, with regard to cable winding, the rotation of the drum in the direction in which the cable is wound onto the cable drum is referred to as "forward rotation," and the rotation of the drum in the opposite direction in which the cable is unwound from the cable drum is referred to as "reverse rotation." Furthermore, the rotation of the cable reel device and the rotation of the cable drum are considered to be synonymous.

[0012] 1 is a vehicle body layout diagram of an electric hydraulic excavator (electric construction machine) 1 according to Example 1. The electric hydraulic excavator 1 has a lower traveling body 2, an upper rotating body 3 rotatably mounted on the lower traveling body 2, a front working mechanism 4 connected to the upper rotating body 3, and a counterweight 5 as an anti-tip measure for suppressing deviation of the center of gravity of the vehicle body when a heavy load is held by the front working mechanism 4.

[0013] The lower traveling body 2 has a frame and a right traveling device 21 and a left traveling device 22 (sometimes collectively referred to as traveling devices 23) provided as a pair on the left and right sides of the frame. The right traveling device 21 and the left traveling device 22 each include a traveling motor and a track wound around the traveling motor. In this embodiment, the traveling motors of the right traveling device 21 and the left traveling device 22 are configured so that their rotation directions are controlled independently of each other. Therefore, the right traveling device 21 and the left traveling device 22 are provided as a pair on the left and right sides of the lower traveling body 2 and perform forward and backward movement independently of each other.

[0014] A cable reel device 6 is mounted at the rear of the undercarriage 2, in this embodiment, between the right traveling device 21 and the left traveling device 22 on the frame of the undercarriage 2. A cable 8, which is connected to an external power source and receives electric power as its power source, is wound and stored in the cable reel device 6 (specifically, a cable drum 18 in the cable reel device 6 as shown in FIG. 3 ). Inside the cable reel device 6, the cable 8 is wound when the cable drum 18 rotates forward, and the cable 8 is unwound when the cable drum 18 rotates reversely. The cable 8 has a portion 8a that contacts the ground, and the portion of this portion closest to the undercarriage 2 is designated as a ground contact point G. The cable 8 has sufficient rigidity to be unwound and stretched when the cable drum 18 is rotated reversely. The cable reel device 6 is also connected to a disconnector 7 by the cable 8. A three-phase induction motor 9, which is the power source of the electric hydraulic excavator 1, is supplied with electric power via the cable 8 from a facility-side power source connected to the disconnector 7.

[0015] Fig. 2 is a diagram showing an example of the configuration of cable wiring from a power plant to an electric hydraulic excavator. As shown in Fig. 2, first, electric power generated at a power plant 10 is transmitted to a substation 11. The transmitted electric power is then sent to each disconnecting switch 7 (only one is shown in Fig. 2) installed at the site, and the power supply to the electric hydraulic excavator 1 is controlled by the disconnecting switch 7, which is an electric power device that opens and closes the voltage of the power circuit when there is no load.

[0016] Thus, when a disconnector 7 is placed at a construction site, it is necessary to connect the disconnector 7 to the vehicle body via a cable 8 in order to transmit power to the electric construction machine 1. Therefore, handling the cable 8 at the site without damaging it can be said to be an issue that accompanies the adoption of a cable reel device 6. The present invention was made in light of this issue, and aims to control the drum rotation direction of the cable reel device 6 to ensure a certain distance or more between the lower traveling body 2 and the ground point of the cable 8. First, the controller for controlling the drum rotation direction of this cable reel device 6 will be described below.

[0017] 3 is a block diagram showing the hardware configuration around the control device (controller) 14 of the cable reel device 6 according to one embodiment. The controller 14 is configured as a computer including, for example, a CPU (Central Processing Unit) and a memory, and is mounted in the cab of the electric hydraulic excavator 1, but does not necessarily have to be mounted in the cab.

[0018] As shown in Figure 3, a right travel lever 12 and a left travel lever 13 are disposed in the cab where the controller 14 is located. The right travel lever 12 operates the right traveling device 21 in a forward direction when tilted forward, and operates the right traveling device 21 in a reverse direction when tilted backward. Similarly, the left travel lever 13 operates the left traveling device 22 in a forward direction when tilted forward, and operates the left traveling device 22 in a reverse direction when tilted backward.

[0019] The right travel lever 12 and the left travel lever 13 are configured to adjust the forward / reverse operating speed of the right travel device 21 and the left travel device 22 depending on the angle at which they are tilted. A camera 15 and a GPS 16 are also mounted outside the cab. The cable reel device 6, to which the controller 14 is connected, specifically includes a cable drum 18 around which the cable 8 is wound and a cable reel rotation drive device 17 that rotates the cable drum 18. The cable reel rotation drive device 17 includes, for example, a motor that actually rotates the cable drum 18 and a motor driver that receives operation signals from the controller 14 and controls the motor. Preferably, the motor is a three-phase induction motor. In this case, the cable reel device 6 is rotated by inverter control or three-phase switching control of the three-phase induction motor.

[0020] Lever signals from the right travel lever 12 and the left travel lever 13 are input to the controller 14 from inside the cab, and signals from a camera 15 and a GPS (Global Pointing System) 16 are input from outside the cab. A control signal is output from the controller 14 to a cable reel rotation drive device 17 to control the rotation of a cable drum 18 around which the cable 8 is wound.

[0021] As will be described in more detail below, in one embodiment, when the controller 14 receives an operating lever signal from the right travel lever 12 or the left travel lever 13, it determines whether the action indicated by that signal requires unwinding the cable 8, and if it does require unwinding the cable 8, it sends a control signal to the cable reel rotation drive device 17 to rotate the cable drum 18 in the direction to unwind the cable 8. In all other situations, the cable drum 18 is always biased in the direction to reel in the cable 8. However, this biasing force is such that the cable 8 will be pulled out from the cable drum 18 if a certain level of tension or more is applied to the cable 8 due to, for example, the forward movement of the vehicle.

[0022] In another embodiment, the controller 14 receives signals from the camera 15 and the GPS 16 in addition to signals from the right travel lever 12 and the left travel lever 13, and determines whether or not the situation calls for reeling out the cable 8. These will be described in detail later.

[0023] 4 is a functional block diagram showing the functional units of the controller 14 common to all the embodiments of the present invention. As shown in FIG. 4, the controller 14 includes, as functional units, an input / output unit 141, a rotation direction control unit 142, a counter unit 143, a relative position relationship calculation unit 144, and a grounding point determination unit 145, as well as a disconnector position information storage unit 146 that stores disconnector position information. Each of these units represents a function of the controller 14 that is realized, for example, by a CPU executing a computer program stored in memory.

[0024] The input / output unit 141 controls the input and output of signals to and from various devices connected to the controller 14. The rotation direction control unit 142 normally outputs a command signal to rotate the cable drum 18 in the direction of winding the cable 8. However, when it is determined that the cable 8 needs to be unwound, it generates a signal to the cable reel rotation drive device 17 to instruct it to do so. The counter unit 143 counts the time during which the operation signal is received from the right travel lever 12 and the left travel lever 13. The relative positional relationship calculation unit 144 calculates the relative positional relationship between the vehicle body and the disconnector 7 based on the vehicle body's own positional information received from the GPS 16 and the positional information of the disconnector 7 stored in the disconnector position information storage unit 146. The ground contact point determination unit 145 determines the position of the ground contact point G, which is the portion 8a of the cable 8 that is closest to the undercarriage 2, based on the image received from the camera 15. The disconnector position information storage unit 146 stores the positional information of the disconnector 7 installed at the site.

[0025] Next, a situation in which the undercarriage of the construction machine runs over the cable, which is a risk that has remained in the past, will be described with reference to FIG.

[0026] Note that Figure 5 shows the operation of the electric hydraulic excavator 1 when the electric hydraulic excavator 1 has a so-called backhoe-type configuration in which the bucket is attached facing in the reverse direction. In this situation, it is assumed that the electric hydraulic excavator 1 excavates the ground in the position shown in Figure 5(a) and loads the excavated soil into the dump truck 19, and then moves to the position shown in Figure 5(b) and performs the same operation. That is, after the operation shown in Figure 5(a), the electric hydraulic excavator 1 moves backward, turns right and moves forward, and then turns left and moves forward. Note that, as mentioned above, the cable reel device 6 is always urged in the rewinding direction by the cable reel rotation drive device 17 of the cable drum 18, so the cable 8 is stretched and taut while running along the ground.

[0027] At this time, the electric hydraulic excavator 1 will turn at two points indicated by "A" and "B" in Fig. 5(a). As a result, there is a risk that the cable 8 will be stepped on at the right rear of the undercarriage 2 when turning right, as shown at "A'" in Fig. 5(c), and there is also a risk that the cable 8 will be stepped on at the left rear of the undercarriage 2 when turning left, as shown at "B'" in Fig. 5(d).

[0028] This trampling of the cable occurs due to the positional relationship between the grounding point G of the cable 8 and the electric hydraulic excavator 1, and this will be explained with reference to FIG.

[0029] In each diagram in Fig. 6, the symbol VC is an imaginary circle indicating the distance from the center of the undercarriage of the electric hydraulic excavator 1 to the ground contact point G of the cable 8. Fig. 6(a) shows a conventional state in which the cable drum 18 is always biased in the winding direction to wind the cable 8, with part of the cable 8 in contact with the ground but stretched in a substantially straight line. In this case, if the distance between the ground contact point G of the cable 8 and the undercarriage 2 is short as shown in Fig. 6(a), there is a risk that the undercarriage 2 will run over the cable 8 on the disconnector 7 side of the ground contact point G when it turns.

[0030] On the other hand, in this embodiment, the cable drum 18 is rotationally driven in the payout direction under predetermined conditions to pay out the cable 8 from the cable drum 18. Then, as shown in Figure 6(b), the ground contact point G of the cable 8 moves away from the undercarriage 2 of the electric hydraulic excavator 1. This is because the cable 8, which is intended to be handled outdoors, has high rigidity, and when the cable drum 18 is not biased in the winding direction and no tension is acting on the cable 8, the cable 8 maintains a gently slackened state for several meters until it comes into contact with the ground.

[0031] Therefore, when the electric hydraulic excavator 1 makes a reverse turn while reeling out the cable 8 as in this embodiment, a certain distance or more is ensured between the lower running body 2 of the electric hydraulic excavator 1 and the ground contact point G of the cable 8, as shown in Figure 6 (c), and the lower running body 2 can make the turn without stepping on the cable 8.

[0032] Next, the conditions for paying out the cable 8 will be explained using the diagram in Fig. 7. As mentioned above, the cable drum 18 to which the cable 8 is connected is located at the rear of the undercarriage 2 of the electric hydraulic excavator 1, and the cable 8 is disposed almost entirely behind the undercarriage 2 around the vehicle body. Therefore, as shown in the top three rows of Fig. 7, when the vehicle body is moving forward, there is no possibility that the undercarriage 2 will run over the cable 8, and the drum rotation remains in the forward direction.

[0033] Also, when the lower traveling body 2 moves backward without turning, the positional relationship between the lower traveling body 2 and the ground contact point G of the cable 8 is maintained while the cable 8 moves backward and is wound up, so there is no possibility that the lower traveling body 2 will step on the cable 8.

[0034] On the other hand, when moving backward while gently turning left and right with one of the right travel lever 12 and the left travel lever 13 set to reverse (full) and the other set to reverse (half), or when turning on the spot with one of the right travel lever 12 and the left travel lever 13 set to forward and the other set to reverse, there is a possibility that the lower traveling body 2 may step on the cable 8, as described in Figures 5 and 6. In such cases, the cable drum 18 is reversed to pay out the cable 8 and move the ground contact point G of the cable 8 away from the lower traveling body 2, thereby avoiding the risk of the lower traveling body 2 stepping on the cable 8.

[0035] 8 is a flowchart showing the process executed by the controller 14 in this embodiment. First, in step S1, the input / output unit 141 of the controller 14 receives operation signals from the right travel lever 12 and the left travel lever 13.

[0036] In step S2, the rotation direction control unit 142 of the controller 14 checks the received operation signal against the chart in Figure 7 and determines whether the vehicle body movement instructed by the operation signal is an operation to pay out the cable 8, i.e., an operation to turn in place or while moving backward. If the vehicle body movement satisfies the cable payout condition, the process proceeds to step S3; if not, the process ends.

[0037] In step S3, the rotation direction control unit 142 of the controller 14 generates a control signal for rotating the cable drum 18 in the reverse direction and transmits it to the cable reel rotation drive device 17 of the cable reel device 6. In response to the signal, the cable reel rotation drive device 17 drives the cable drum 18 in the reverse direction.

[0038] According to this embodiment, when the vehicle makes a gentle left or right turn while turning or reversing, a certain distance or more is maintained between the lower traveling structure 2 and the ground contact point G of the cable 8, making it possible to prevent the cable 8 from contacting or being stepped on by the lower traveling structure 2. Furthermore, since there is no need to manually move the cable while the vehicle body is stopped, the lower traveling structure 2 can be operated without stopping, significantly reducing downtime.

[0039] 9 to 11, an electric construction machine according to Example 2 will be described. In Example 2, the vehicle layout of the electric construction machine 1 and the functional configuration of the controller 14 are the same as those in Example 1, and therefore description thereof will be omitted.

[0040] This embodiment differs from the first embodiment in that it uses position information from a GPS 16 mounted outside the cab of the vehicle body. In the first embodiment, only the vehicle body movement was the condition for paying out the cable 8. However, in this embodiment, the conditions are further subdivided, and the positional relationship between the vehicle body and the disconnector 7 and the vehicle body movement are the conditions for paying out the cable 8.

[0041] 9 is a diagram for explaining the rotation control of the cable reel device 6 using GPS signals in this embodiment. In Fig. 9, "vehicle body position relative to the disconnector" indicates the position of the vehicle body as seen from the disconnector 7 when standing in the same position as the disconnector 7 and facing the same direction as the vehicle body.

[0042] Nos. 1 and 2 in Fig. 9 correspond to Fig. 10(a). If the vehicle were to turn left from the state shown in Fig. 10(a) (left turn), there is a risk that the cable 8 would be stepped on by the left rear of the lower running body 2, so the cable drum 18 is rotated in the reverse direction to pay out the cable 8. Conversely, even if the vehicle were to turn right in this state, there would be a certain distance between the right rear of the lower running body 2 and the cable 8 at the start of the turn, so there is no risk of the cable 8 being stepped on for a while, and the cable drum 18 is kept rotating in the forward direction.

[0043] Similarly, Nos. 3 and 4, 5 and 6, and 7 and 8 in Fig. 9 correspond to Figs. 10(b), (d), and (c), respectively. The conditions for paying out the cable 8 are the same as those described with reference to Fig. 10(a).

[0044] 9 correspond to (b), (c), (a), and (d) in Fig. 11. In this case, the conditions for paying out the cable 8 are the same as those shown in Fig. 9.

[0045] From the above, the following can be said about this embodiment: That is, regarding the positional relationship between the disconnector 7 and the car body, regardless of whether the car body is in front, behind, or to the side of the disconnector 7, when the car body is on the left side of the disconnector 7, a right turn is required for letting out the cable 8, and conversely, when the car body is on the right side of the disconnector 7, a left turn is required for letting out the cable 8.

[0046] From another perspective, regardless of the relative positions of the disconnector 7 and the vehicle body, the condition for unwinding the cable 8 is either a right turn or a left turn, whichever has the shorter turning distance until the vehicle faces the direction of the disconnector 7.

[0047] The flowchart showing the processing executed by the controller 14 in this embodiment is also similar to that of the first embodiment shown in Fig. 8. However, in this embodiment, the determination of the cable payout condition in step S2 is made by the relative positional relationship calculation unit 144 of the controller 14 determining the orientation of the vehicle body relative to the disconnector 7 from its own positional information received from the GPS 16 and the positional information of the disconnector 7 stored in the disconnector positional information storage unit 146, and referring to the list in Fig. 9.

[0048] As described above, according to this embodiment, the rotation of the cable drum 18 is controlled under more detailed conditions based on the positional relationship between the car body and the disconnector 7, making it possible to more reliably avoid the risk of the lower running body 2 stepping on the cable 8.

[0049] [Example 3] Next, an electric construction machine according to Example 3 will be described with reference to Fig. 12. In Example 3, the vehicle layout of the electric construction machine 1 and the functional configuration of the controller 14 are the same as those in Example 1, and therefore description thereof will be omitted.

[0050] In this embodiment, instead of changing the conditions for letting out the cable 8, the time when the cable 8 is let out after a turn is counted, and an operation is added to wind up the cable 8 by the amount counted after the turn is completed.

[0051] Specifically, consider a case where a vehicle makes a right turn for five seconds, then a left turn for two seconds, and then another right turn for three seconds. In this case, the right turn and the left turn take a total of eight and two seconds, respectively, so two seconds are subtracted from eight to get six seconds. After the turn is completed, the cable drum 18 is rotated forward for six seconds to wind up the cable.

[0052] According to this embodiment, the cable 8 that was unwound during the turn is rewound after the turn, so that the cable 8 is quickly returned to the state it was in before the turn, in which it was always taut, and it is possible to avoid problems such as the remaining cable 8 interfering with other shovels.

[0053] 13 is a diagram showing the vehicle body layout of an electric hydraulic excavator 1 according to Example 4. In this example, a camera 15 is mounted on the vehicle body of the electric hydraulic excavator 1, and a monitor 20 is mounted in the cab.

[0054] In this embodiment, the camera 15 is provided to monitor the ground contact point of the cable 8. That is, as explained in the above-mentioned embodiments, it is important to keep the ground contact point G of the cable 8 away from the undercarriage 2 of the electric hydraulic excavator 1, and in this embodiment, the specific position of the ground contact point G is determined by directly monitoring the cable 8 with the camera 15, and when the position of the ground contact point G comes within a predetermined threshold value of the vehicle body (specifically, the rear end of the undercarriage 2), an alarm or the like is issued to the monitor 20 in the cab or to an external monitor or the like.

[0055] The position of the ground contact point G can be determined by observation by a person watching the monitor, but it is preferable to automatically determine it by image analysis.

[0056] According to this embodiment, even if the cable 8 is unwound during a turn in accordance with the operation signals received from the right travel lever 12 and the left travel lever 13, it is possible to prepare for an unforeseen event such as the ground contact point G of the cable 8 not separating from the vehicle body due to the influence of an obstacle or the like, causing the lower travel body 2 to step on the cable 8.

[0057] Finally, Figure 14 is a diagram for explaining the maximum length of the cable 8 that can be let out. Since the tension of the cable 8 is kept constant while the cable 8 is being let out while the vehicle is turning, it is considered that the positional relationship of the ground contact point G with the vehicle body is also kept constant during that time. Furthermore, as shown in Figures 14(a) and 14(b), when the vehicle body turns by a maximum of 180 degrees, the positional relationship between the disconnector 7 and the vehicle body is opposite before and after the turn. Therefore, the maximum length L of the cable 8 that can be let out during a turn is the length of the arc of a semicircle whose radius is the distance between the center of the vehicle body and the ground contact point G before the turn, as shown in Figure 14(c).

[0058] The above-described embodiment of the present invention provides the following advantageous effects.

[0059] (1) The electric construction machine of the present invention has a lower traveling body including a pair of traveling devices provided on the left and right sides that move forward and backward independently of each other, and is driven by being connected to an external power source via a cable. It has a cable reel device provided at the rear end of the lower traveling body between the pair of traveling devices, which winds and stores the cable, and which winds up the cable by forward drive and unwinds the cable by reverse drive, and a control device which controls the rotation direction of the cable reel device depending on the operating state of the lower traveling body.

[0060] With the above configuration, a fixed distance is maintained between the vehicle body and the cable, making it possible to prevent the cable from coming into contact with the lower running body or being stepped on.

[0061] (2) The control device drives the cable reel device in reverse when the undercarriage turns while moving backward or turns on the spot. This invention is applied because there is a risk of stepping on the cable when the construction machine performs such an operation.

[0062] (3) The cable reel rotation drive device is a three-phase induction motor, and the rotation drive of the cable reel device is performed by inverter control or three-phase switching control. The construction machinery to which the present invention is applied is often large, so it is preferable to use a high-output three-phase induction motor.

[0063] (4) The control device includes a disconnector position information storage unit that stores position information for the disconnector to which the cable is connected, and a relative position relationship calculation unit that calculates the positional relationship between the electric construction machine and the disconnector based on the position information for the disconnector and the position information for the electric construction machine, and controls the rotation direction of the cable reel device based on the calculation results of the relative position relationship calculation unit. This makes it possible to determine whether to pay out the cable depending on the cable arrangement situation, which changes depending on the positional relationship between the disconnector and the construction machine.

[0064] (5) When the undercarriage makes a right turn or a left turn, whichever turns the shorter distance until it faces the disconnector, the control device reverses the rotation direction of the cable reel device. As in (1), this invention is applied because there is a risk of stepping on the cable when the construction machine performs such an operation.

[0065] (6) The control device reverses the rotation direction of the cable reel device when the undercarriage turns left with the electric construction machine located to the right of the disconnector as viewed from the disconnector, or turns right with the electric construction machine located to the left of the disconnector. As with (1) and (5), this invention is applied because there is a risk of stepping on the cable when the construction machine performs such operations.

[0066] (7) The control device has a counter unit that counts the time that the control lever signal is input, and while the undercarriage turns left or right on the spot, the counter unit adds the time while turning in one direction and subtracts the time while turning in the opposite direction, and after the left or right turn is completed, the control device rotates the cable reel device in the forward direction for the added time. This makes it possible to accumulate the time that the cable is being paid out, and by winding the cable for an appropriate amount of time after the turn, it is possible to quickly return the cable to its taut state before the turn.

[0067] (8) The control device has a grounding point determination unit that receives images from a camera that observes the grounding point of the cable and determines the position of the grounding point, and the grounding point determination unit issues a warning when the grounding point of the cable comes within a predetermined distance of the electric construction machine. This makes it possible to prepare for unexpected situations such as when the grounding point of the cable remains stuck on the vehicle body due to an obstacle or the like, causing the undercarriage to run over the cable.

[0068] (9) The electric construction machine is an electric hydraulic excavator having an upper rotating body that is rotatably provided with respect to a lower traveling body, which is a typical example of a construction machine to which the present invention is applied.

[0069] It should be noted that the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to embodiments that include all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations.

[0070] 1 Electric hydraulic excavator (electric construction machine), 2 Lower traveling body, 6 Cable reel device, 7 Disconnector, 8 Cable, 9 Three-phase induction motor, 12 Right traveling lever, 13 Left traveling lever, 14 Controller (control device), 15 Camera, 16 GPS, 21 Right traveling device, 22 Left traveling device, 23 Traveling device, 142 Rotation direction control unit, 143 Counter unit, 144 Relative position relationship calculation unit, 145 Grounding point determination unit, 146 Disconnector position information storage unit, G Grounding point

Claims

1. An electric construction machine having a lower traveling body including a pair of left and right traveling devices that move forward and backward independently of each other, and that is driven by being connected to an external power source via a cable, characterized in that it has a cable reel device that is provided at the rear end of the lower traveling body between the pair of traveling devices, that winds and stores the cable, that winds up the cable when driven in forward direction, and that pays out the cable when driven in reverse direction, and a control device that controls the rotation direction of the cable reel device depending on the operating state of the lower traveling body.

2. An electric construction machine as claimed in claim 1, characterized in that the control device drives the cable reel device in reverse when the undercarriage turns while moving backward or turns on the spot.

3. An electric construction machine according to claim 1, wherein the control device comprises a disconnector position information storage unit that records position information of the disconnector to which the cable is connected, and a relative position relationship calculation unit that calculates the positional relationship between the electric construction machine and the disconnector based on the position information of the disconnector and the position information of the electric construction machine, and controls the direction of rotation of the cable reel device based on the calculation results of the relative position relationship calculation unit.

4. An electric construction machine as claimed in claim 3, characterized in that the control device reverses the direction of rotation of the cable reel device when the undercarriage makes a right turn or a left turn, whichever has the shorter turning distance before facing the disconnector.

5. An electric construction machine as claimed in claim 3, characterized in that the control device reverses the direction of rotation of the cable reel device when the undercarriage turns left while the electric construction machine is located to the right of the disconnector as viewed from the disconnector, or turns right while the undercarriage is located to the left of the disconnector.

6. An electric construction machine as claimed in claim 1, wherein the control device has a counter unit that counts the time during which a signal from the operating lever is input, and the counter unit adds the time during which the lower traveling body turns left and right on the spot while turning in one direction and subtracts the time during which it turns in the opposite direction, and after the left and right turn is completed, the control device rotates the cable reel device in the forward direction for the amount of time added.

7. An electric construction machine as described in claim 1, wherein the control device has a grounding point determination unit that receives images from a camera that observes the grounding point of the cable and determines the position of the grounding point, and the grounding point determination unit issues a warning when the grounding point of the cable comes within a predetermined distance of the electric construction machine.

8. An electric construction machine according to claim 1, characterized in that the electric construction machine is an electric hydraulic excavator having an upper rotating body that is rotatably mounted relative to the lower traveling body.

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