Electric construction machinery

Abstract

To provide an electrically-driven construction machine that enables electrical equipment including an electric motor, an inverter, and a charger to be cooled according to its operation mode, allowing for improved cooling efficiency of the electrical equipment, reduction in necessary cost for cooling equipment, and the like.SOLUTION: A cooling pipe line 18 is provided with: a motor side pipe line 21 connecting a radiator 16, an electric motor 10, and an inverter 13; and a charger side pipe line 22 connecting the radiator 16 and a charger 14. The cooling pipe line 18 is provided with a motor side changeover valve 25 and a charger side changeover valve 26 for switching a supply destination of cooling water cooled by the radiator 16 to one or both of the motor side pipe line 21 and the charger side pipe line 22. Further, a controller 27 is provided to control the motor side changeover valve 25 and the charger side changeover valve 26 depending on the operation mode: a charging mode, an internal power mode, or an external power mode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric construction machine such as a hydraulic excavator that is equipped with an electric motor as a power source. [Background technology]

[0002] Generally, a hydraulic excavator, which is a typical example of construction machinery, comprises a self-propelled lower traveling body, an upper rotating body that is rotatably mounted on the lower traveling body via a rotating device, and a working device that is provided in front of the upper rotating body and is operated by a hydraulic actuator. In recent years, as a measure to curb global warming and air pollution, electric hydraulic excavators that use an electric motor as a power source have been put into practical use. In this electric hydraulic excavator, a hydraulic pump is driven by the electric motor to supply pressure oil (hydraulic oil) for operation to the hydraulic actuator.

[0003] The upper rotating body of an electric hydraulic excavator is equipped with an electric motor as a power source, a hydraulic pump that is driven by the electric motor to supply hydraulic oil to a hydraulic actuator, a battery device that stores electricity to be supplied to the electric motor, an inverter that converts electricity supplied from the battery device and supplies it to the electric motor, and a charger that is connected to an external power source to convert electricity from the external power source and supply it to the battery device.

[0004] The upper rotating body also includes a radiator that cools the cooling water, a cooling pipeline that connects the radiator to electrical equipment such as an electric motor, an inverter, and a charger, and a cooling water pump that supplies the cooling water cooled by the radiator to the cooling pipeline (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-190107 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, electric hydraulic excavators perform work in a plurality of different operating configurations (a plurality of modes). Among these modes, a charging mode in which an external power source is connected to a charger and a battery device are charged, and an internal power mode in which an electric motor is driven by power stored in the battery device, have conventionally been known. Furthermore, in recent years, an external power mode has also become known in which, in order to extend operating time, an electric motor is driven with the external power source connected to a charger, and surplus power is stored in the battery device.

[0007] The electrical equipment used varies in each mode. Specifically, in charging mode, the charger operates, in internal power mode, the electric motor and inverter operate, and in external power mode, the charger, electric motor, and inverter operate.

[0008] In contrast, the electric hydraulic excavator disclosed in Patent Document 1 connects the radiator, electric motor, inverter, and charger via cooling water channels. However, depending on the mode of the electric hydraulic excavator, the circuit configuration supplies cooling water to electrical equipment that does not require cooling. Therefore, resistance (pipe resistance) increases when the cooling water flows through the cooling pipes, reducing the cooling efficiency of the electrical equipment that requires cooling. Furthermore, in order to maintain the cooling efficiency of the electrical equipment, a large amount of cooling water must be supplied, which necessitates increasing the size of the cooling water pump and thickening the cooling pipes, resulting in a problem of increased costs.

[0009] An object of the present invention is to provide an electric construction machine that can cool electrical equipment including an electric motor, inverter, and charger depending on the mode, thereby improving the cooling efficiency of the electrical equipment and reducing the costs required for cooling equipment. [Means for solving the problem]

[0010] The present invention provides a vehicle body capable of self-propelling, the vehicle body including an electric motor as a power source, and a battery device for storing electricity to be supplied to the electric motor. , outside a charger that is connected to an external power source to convert electric power from the external power source and supply the converted electric power to the battery device; a radiator that cools the coolant; and a power supply between the radiator and the electric motor. Tao a cooling pipe provided to connect the radiator and the charger; a cooling water pump that supplies cooling water cooled by the radiator to the cooling pipe; a controller for controlling the flow of cooling water cooled by the radiator; In the electric construction machine equipped with the above, the cooling pipe is Ta and a motor-side pipe connecting the radiator and the charger, and a charger-side pipe connecting the radiator and the charger, wherein the cooling pipe is provided with a switching valve that switches the supply destination of the cooling water cooled by the radiator to one or both of the motor-side pipe and the charger-side pipe; The switching valve includes a normally closed motor-side switching valve provided in the motor-side pipe and a normally closed charger-side switching valve provided in the charger-side pipe, and the controller A charging mode in which the battery device is charged while the external power source is connected to the charger. Then, the charger side switching valve is opened so that the cooling water cooled by the radiator flows into the charger side pipe. an internal power mode in which the electric motor is driven by the power stored in the battery device; Then, the motor side switching valve is opened so that the cooling water cooled by the radiator flows into the motor side pipe. an external power mode in which the electric motor is driven by power from the external power source, and surplus power is charged into the battery device; Then, the charger side switching valve and the motor side switching valve are opened so that the cooling water cooled by the radiator flows into the charger side pipe and the motor side pipe. It is characterized by the following. [Effects of the Invention]

[0011] According to the present invention, electrical equipment including an electric motor, an inverter, and a charger can be cooled depending on the mode, thereby improving the cooling efficiency of the electrical equipment and reducing the cost required for cooling equipment. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a left side view showing an electric hydraulic excavator according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of an upper rotating body. [Figure 3] FIG. 2 is a block diagram showing a connection system of electrical equipment in a charging mode. [Figure 4] FIG. 2 is a block diagram showing a connection system of electrical equipment in an internal power mode. [Figure 5] FIG. 4 is a block diagram showing a connection system of electrical equipment in an external power mode. [Figure 6] 4 is a flowchart showing a control process related to cooling of electrical equipment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of an electric construction machine according to the present invention will be described in detail with reference to Figs. 1 to 6, taking as an example a case where the machine is applied to an electric hydraulic excavator.

[0014] In Figure 1, an electric hydraulic excavator 1, which is a representative example of an electric construction machine, is equipped with a self-propelled crawler-type lower traveling body 2 and an upper rotating body 4 that is rotatably mounted on the lower traveling body 2 via a rotating device 3. The body of the electric hydraulic excavator 1 is made up of the lower traveling body 2 and the upper rotating body 4. A blade device (earth removal device) 5 is provided on the front side of the lower traveling body 2 so as to be rotatable in the vertical direction, and earth removal work and the like are performed using this blade device 5. A swing-type working device 6 is provided on the front side of the upper rotating body 4, and this working device 6 is used to perform work such as excavating earth and sand.

[0015] The swing-type working device 6 is configured to include a swing post 6A mounted on the front side of a revolving frame 7 (described later) so as to be swingable in the left-right direction, a boom 6B rotatably attached to the swing post 6A, an arm 6C rotatably attached to the tip of the boom 6B, and a bucket 6D rotatably attached to the tip of the arm 6C in the up-down direction. The working device 6 also includes a swing cylinder (not shown) that swings the swing post 6A, a boom cylinder 6E that rotates the boom 6B, an arm cylinder 6F that rotates the arm 6C, and a bucket cylinder 6G that rotates the bucket 6D.

[0016] The upper rotating body 4 is rotatably mounted on the lower traveling body 2 via a rotating device 3, and performs a rotating operation on the lower traveling body 2. As shown in Figures 1 and 2, the upper rotating body 4 is configured to include a rotating frame 7, a cab 8, a counterweight 9, an electric motor 10, a hydraulic pump 11, a battery device 12, an inverter 13, a charger 14, a radiator 16, a cooling pipe 18, a motor-side cooling water pump 23, a charger-side cooling water pump 24, a motor-side switching valve 25, a charger-side switching valve 26, and a controller 27, which will be described later.

[0017] The rotating frame 7 forms the base of the upper rotating body 4. The rotating frame 7 is attached to the lower traveling body 2 via the rotating device 3, and the working device 6 is attached to the front side of the rotating frame 7.

[0018] The cab 8 is provided on the left front side of the revolving frame 7. Inside the cab 8 is a cab where an operator sits. The cab is provided with a driver's seat where the operator sits, a travel lever pedal that controls the travel of the undercarriage, and an operation control lever that controls the operation of the revolving device 3 and the work device 6 (none of which are shown). Also provided inside the cab 8 is, for example, a controller 27, which will be described later.

[0019] The counterweight 9 is provided at the rear of the revolving frame 7. The counterweight 9 is a weight for maintaining a weight balance with the working device 6. A power supply cable 29, which will be described later, is detachably connected to the top of the counterweight 9.

[0020] The electric motor 10 constitutes the power source of the electric hydraulic excavator 1. The electric motor 10 rotates an output shaft using electric power supplied from a battery device 12 (described later), and drives a hydraulic pump 11 connected to this output shaft. In addition, for example, the electric motor 10 is configured as an AC motor. DC power from the battery device 12 is converted to AC power by an inverter 13 and supplied to the electric motor 10.

[0021] Here, the electric motor 10 generates heat by converting electrical energy into thermal energy through resistance. For this reason, the electric motor 10 is provided with a cooling water passage (not shown) through which cooling water flows. A motor-side pipe 21, which will be described later, is connected to this cooling water passage.

[0022] The hydraulic pump 11 is driven by the electric motor 10 to supply hydraulic oil from a hydraulic oil tank 30 (described later) to hydraulic actuators such as the cylinders 6E to 6G of the working device 6, the swing hydraulic motor of the swing device 3, and the traveling hydraulic motor of the undercarriage 2. The hydraulic pump 11 is connected to the output shaft of the electric motor 10.

[0023] The battery device 12 stores electric power to be supplied to the electric motor 10. As shown in FIGS. 3 to 5 , the battery device 12 is connected to a charger 14 via a switch 15. The battery device 12 is also connected to the electric motor 10 via the switch 15 and an inverter 13. In a charging mode, which will be described later, a power supply cable 29 is connected to the charger 14, and external electric power (commercial power source 28) is converted into DC electric power and charged in the battery device 12. In an internal power mode, DC electric power from the battery device 12 is converted into AC electric power by the inverter 13 and supplied to the electric motor 10. In an external power mode, external electric power is similarly converted by the inverter 13 and supplied to the electric motor 10, while surplus external electric power is charged in the battery device 12.

[0024] The inverter 13 is provided between the electric motor 10 and the switch 15. The inverter 13 converts DC power supplied from the battery device 12 into AC power and supplies it to the electric motor 10. The inverter 13 generates heat due to the load (resistance) generated when switching power. For this reason, the inverter 13, like the electric motor 10, is provided with a cooling water passage (not shown) through which cooling water flows. A motor-side pipe 21 is connected to this cooling water passage following the electric motor 10.

[0025] Charger 14 is connected to commercial power supply 28, which is an external power source, and converts AC power from commercial power supply 28 into DC power and supplies it to battery device 12. Charger 14 is electrically connected to battery device 12 via switch 15. A power supply cable 29 from commercial power supply 28 can be connected to charger 14. Charger 14 generates heat due to the load (resistance) generated when switching power. For this reason, charger 14, like inverter 13, is provided with a cooling water passage (not shown) through which cooling water flows. Charger-side pipe 22 is connected to this cooling water passage.

[0026] The switch 15 is provided between the charger 14 and the battery 12, and between the battery 12 and the inverter 13. In a charging mode (FIG. 3) in which the power supply cable 29 is connected to the charger 14, the switch 15 switches so that power from the commercial power source 28 is supplied to the battery 12. In an internal power mode (FIG. 4), the switch 15 switches so that power from the battery 12 is supplied to the inverter 13 and the electric motor 10. In an external power mode (FIG. 5), the switch 15 switches so that external power is supplied to the inverter 13 and the electric motor 10, and any surplus external power is supplied to the battery 12.

[0027] The radiator 16 is a heat exchanger that cools the coolant used to cool electrical equipment such as the electric motor 10, the inverter 13, and the charger 14. The radiator 16 can lower the temperature of the coolant by dissipating the heat of the coolant flowing through its tubes into cooling air generated by the electric fan 17. An outlet pipe 19 of a cooling pipe 18 (described later) is connected to the outlet side of the coolant of the radiator 16. On the other hand, an inlet pipe 20 of the cooling pipe 18 (described later) is connected to the inlet side of the coolant of the radiator 16.

[0028] Next, a cooling structure for electrical equipment such as the electric motor 10, inverter 13, charger 14, etc., which is a characteristic feature of this embodiment, will be described.

[0029] The cooling pipe 18 is provided to connect the radiator 16 with the electric motor 10, the inverter 13, and the charger 14. The configuration of the cooling pipe 18 will be described with reference to an example of connection when cooling some electrical equipment (electric motor 10, inverter 13, charger 14). The configuration of the cooling pipe 18 is not limited to that of the following embodiment, except that the cooling pipe 18 branches off to the electric motor 10 side and the charger 14 side.

[0030] The cooling pipe 18 includes an outlet pipe 19 having one end on the upstream side in the flow direction of the cooling water connected to the cooling water outlet side of the radiator 16, an inlet pipe 20 having the other end on the downstream side in the flow direction of the cooling water connected to the cooling water inlet side of the radiator 16, a motor-side pipe 21 having one end connected to the other end of the outlet pipe 19, a midway portion connected to the electric motor 10 and the inverter 13, and the other end connected to one end of the inlet pipe 20, and a charger-side pipe 22 having one end connected to the other end of the outlet pipe 19, a midway portion connected to the charger 14, and the other end connected to one end of the inlet pipe 20. As a result, the cooling pipe 18 can branch the cooling water flowing out from the radiator 16 into the motor-side pipe 21 and the charger-side pipe 22 and supply them. The cooling pipe 18 can also return the cooling water branched into the motor-side pipe 21 and the charger-side pipe 22 to the inlet pipe 20 and return it to the radiator 16.

[0031] The motor-side pipe 21 is made up of a supply pipe 21A that connects the radiator 16 and the electric motor 10 via the outlet pipe 19, a relay pipe 21B that connects the electric motor 10 and the inverter 13, and a return pipe 21C that connects the inverter 13 and the inlet pipe 20 (radiator 16). A motor-side cooling water pump 23 and a motor-side switching valve 25, which will be described later, are provided in the supply pipe 21A.

[0032] The charger-side pipe 22 is composed of a supply pipe 22A that connects the radiator 16 and the charger 14 via the outlet pipe 19, and a return pipe 22B that connects the charger 14 and the inlet pipe 20 (radiator 16). A charger-side cooling water pump 24 and a charger-side switching valve 26, which will be described later, are provided in the supply pipe 22A.

[0033] The motor-side cooling water pump 23 is provided in the supply line 21A of the motor-side line 21. The motor-side cooling water pump 23 is an electric pump that supplies the cooling water cooled by the radiator 16 to the motor-side line 21. The motor-side cooling water pump 23 is controlled by a controller 27, which will be described later.

[0034] The motor-side cooling water pump 23 only needs to have an output that is sufficient to supply cooling water to cool the electric motor 10 and the inverter 13, among the electrical equipment that requires cooling. This allows it to be made compact, reducing the space required for installation and stabilizing the amount of cooling water discharged. Furthermore, the compact motor-side cooling water pump 23 can keep power consumption low by stabilizing the amount of cooling water discharged.

[0035] The charger-side cooling water pump 24 is provided in the supply pipe 22A of the charger-side pipe 22. The charger-side cooling water pump 24 is an electric pump that supplies the cooling water cooled by the radiator 16 to the charger-side pipe 22. The charger-side cooling water pump 24 is controlled by a controller 27, which will be described later. Like the motor-side cooling water pump 23, the charger-side cooling water pump 24 only needs to have an output that is sufficient to supply cooling water for cooling the charger 14 out of the electrical equipment that requires cooling. Therefore, the charger-side cooling water pump 24 can be made smaller, thereby reducing the installation space, stabilizing the amount of cooling water discharged, and suppressing power consumption.

[0036] The motor-side switching valve 25 is provided in the supply line 21A of the motor-side line 21. The motor-side switching valve 25 is provided upstream of the motor-side cooling water pump 23, i.e., at a position close to the outlet line 19. The motor-side switching valve 25 cooperates with a charger-side switching valve 26 (described later) to switch the supply destination of the cooling water cooled in the radiator 16 to either the motor-side line 21 or the charger-side line 22, or both. The motor-side switching valve 25 is formed, for example, as a normally closed electromagnetic pilot-type switching valve. The motor-side switching valve 25 is controlled by a controller 27.

[0037] The charger-side switching valve 26 is provided in the supply pipe 22A of the charger-side pipe 22. The charger-side switching valve 26 is provided upstream of the charger-side cooling water pump 24, i.e., at a position close to the outlet pipe 19. The charger-side switching valve 26 cooperates with the motor-side switching valve 25 to switch the supply destination of the cooling water cooled in the radiator 16 to either the motor-side pipe 21 or the charger-side pipe 22, or both. Like the motor-side switching valve 25, the charger-side switching valve 26 is formed as a normally-closed electromagnetic pilot-type switching valve. The charger-side switching valve 26 is controlled by a controller 27.

[0038] Here, the motor-side switching valve 25 and the charger-side switching valve 26, which constitute the switching valves, are switched so that the cooling water cooled by the radiator 16 flows into the motor-side pipe 21, as shown by the white arrows in Fig. 2, when the motor-side switching valve 25 is switched to its open side by a control signal from the controller 27. Also, the motor-side switching valve 25 and the charger-side switching valve 26 are switched so that the cooling water cooled by the radiator 16 flows into the charger-side pipe 22, as shown by the black arrows in Fig. 2, when the charger-side switching valve 26 is switched to its open side by a control signal from the controller 27. Furthermore, the motor-side switching valve 25 and the charger-side switching valve 26 are switched so that the cooling water cooled by the radiator 16 flows into both the motor-side pipe 21 and the charger-side pipe 22, when both the motor-side switching valve 25 and the charger-side switching valve 26 are switched to their open sides by the controller 27.

[0039] The controller 27 is provided, for example, in the cab 8. The controller 27 controls the operation of the electric hydraulic excavator 1, and as part of that control, performs control related to the cooling of the electrical equipment. The controller 27 is electrically connected to the motor-side cooling water pump 23, the charger-side cooling water pump 24, the motor-side switching valve 25, and the charger-side switching valve 26. As a result, the controller 27 controls the motor-side switching valve 25 and the charger-side switching valve 26 according to three modes, which will be described later.

[0040] Here, the modes of the electric hydraulic excavator 1 related to the control of the controller 27 will be described.

[0041] The electric hydraulic excavator 1 can store power in the battery 12 by connecting the power supply cable 29, which is connected to a commercial power source 28 as an external power source, to the charger 14. Furthermore, even when the power supply cable 29 is detached from the charger 14, the electric hydraulic excavator 1 can perform work by driving the electric motor 10 using the power stored in the battery 12. Furthermore, with the power supply cable 29 connected to the charger 14, the electric hydraulic excavator 1 can perform work by driving the electric motor 10 using power from the commercial power source 28, and can store surplus power in the battery 12.

[0042] That is, the electric hydraulic excavator 1 operates in three modes. First, in the charge mode shown in Fig. 3, the battery 12 is charged with the commercial power source 28 (power supply cable 29) connected to the charger 14. In the internal power mode shown in Fig. 4, the electric motor 10 is driven by the power stored in the battery 12. Furthermore, in the external power mode shown in Fig. 5, with the commercial power source 28 (power supply cable 29) connected to the charger 14, the electric motor 10 is driven by the power from the commercial power source 28, and the surplus power is stored in the battery 12.

[0043] In the charging mode of Fig. 3, the internal power mode of Fig. 4, and the external power mode of Fig. 5, the electrical equipment indicated by solid lines is the electrical equipment used in each mode, and the electrical equipment indicated by dashed lines is the electrical equipment not used in each mode. More specifically, in the charging mode of Fig. 3, the battery 12, charger 14, and switch 15 are used, and the electric motor 10 and inverter 13 are not used. In the internal power mode of Fig. 4, the electric motor 10, battery 12, inverter 13, and switch 15 are used, and the charger 14 is not used. In the external power mode of Fig. 5, the electric motor 10, battery 12, inverter 13, charger 14, and switch 15 are used.

[0044] The control processing of the controller 27 corresponding to these three modes will be described with reference to the flowchart shown in Fig. 6. Note that the steps in the flowchart shown in Fig. 6 are each indicated by the letter "S", for example, step 1 is indicated as "S1".

[0045] The control process shown in Fig. 6 is started. In S1, the status of the electric circuit related to the operation of the electric hydraulic excavator 1, such as the state of the charging switch, the connection of the power supply cable 29, and whether or not a mode has been input from a monitor device (none of which are shown), is input. In S2, it is determined whether or not the operating mode of the electric hydraulic excavator 1 is in the charging mode based on the status of the electric circuit in S1. If it is determined in S2 that it is in the charging mode (YES), the process proceeds to S3 and S4. In S3, the charger-side selector valve 26 is opened, and in S4, the charger-side cooling water pump 24 is started.

[0046] As a result, the controller 27 takes into consideration heat generation by the charger 14 in the charging mode, and can cool the charger 14 by supplying cooling water to the charger 14 through the charger-side pipe 22 as shown by the black arrow in FIG.

[0047] On the other hand, if it is determined in S2 that the mode is not the charge mode (NO), the process proceeds to S5. In S5, it is determined whether or not the operating mode of the electric hydraulic excavator 1 is in the internal power mode based on the state of the electrical circuit in S1. If it is determined in S5 that the mode is the internal power mode (YES), the process proceeds to S6 and S7. In S6, the motor-side switching valve 25 is opened, and in S7, the motor-side cooling water pump 23 is started.

[0048] As a result, the controller 27 takes into account the heat generated by the electric motor 10 and the inverter 13 in the internal power mode, and can supply cooling water to the electric motor 10 and the inverter 13 through the motor-side pipe 21, as shown by the white arrow in Figure 2, to cool the electric motor 10 and the inverter 13.

[0049] Furthermore, if it is determined in S5 that the mode is not the internal power mode (NO), the external power mode is confirmed, and the process proceeds to S8 and S9. In S8, the charger-side switching valve 26 and the motor-side switching valve 25 are opened, and in S9, the charger-side cooling water pump 24 and the motor-side cooling water pump 23 are started.

[0050] As a result, the controller 27 takes into account the heat generated by the electric motor 10, inverter 13, and charger 14 in the external power mode, and supplies cooling water to the electric motor 10 and inverter 13 through the motor-side pipe 21, as shown by the black and white arrows in Figure 2, and also supplies cooling water to the charger 14 through the charger-side pipe 22, thereby cooling the electric motor 10, inverter 13, and charger 14.

[0051] The hydraulic oil tank 30 is mounted on the revolving frame 7. The hydraulic oil tank 30 stores hydraulic oil to be supplied to the hydraulic actuator, and is connected to the hydraulic pump 11 and the like.

[0052] The electric hydraulic excavator 1 according to this embodiment has the above-described configuration, and its operation will be described below.

[0053] When performing excavation work or the like using the electric hydraulic excavator 1, the operator sits in the cab 8 and operates the electric motor 10 to drive the hydraulic pump 11. In this state, the operator operates a travel lever pedal (not shown) to cause the electric hydraulic excavator 1 to travel to the work site. After the electric hydraulic excavator 1 has moved to the work site, the operator can operate a work operation lever (not shown) to rotate the upper rotating body 4 while using the work device 6 to perform excavation work of earth and sand or the like.

[0054] Thus, according to this embodiment, the cooling pipe 18 includes a motor-side pipe 21 that connects the radiator 16, the electric motor 10, and the inverter 13, and a charger-side pipe 22 that connects the radiator 16 and the charger 14. The cooling pipe 18 is provided with a motor-side switching valve 25 and a charger-side switching valve 26 that switch the supply destination of the cooling water cooled by the radiator 16 to either or both of the motor-side pipe 21 and the charger-side pipe 22. Furthermore, a controller 27 is provided to control the motor-side switching valve 25 and the charger-side switching valve 26 according to three modes: a charging mode (FIG. 3) in which the battery device 12 is charged while a commercial power source 28, which serves as an external power source, is connected to the charger 14; an internal power mode (FIG. 4) in which the electric motor 10 is driven by the power charged in the battery device 12; and an external power mode (FIG. 5) in which the commercial power source 28 is connected to the charger 14, the electric motor 10 is driven by power from the commercial power source 28, and surplus power is charged to the battery device 12.

[0055] Therefore, in the charging mode using the charger 14, the controller 27 can control the motor-side selector valve 25 and the charger-side selector valve 26 so that the cooling water flows only to the charger-side pipe 22. Also, in the internal power mode using the electric motor 10 and the inverter 13, the controller 27 can control the motor-side selector valve 25 and the charger-side selector valve 26 so that the cooling water flows only to the motor-side pipe 21. Furthermore, in the external power mode using the electric motor 10, the inverter 13, and the charger 14, the controller 27 can control the motor-side selector valve 25 and the charger-side selector valve 26 so that the cooling water flows to both the motor-side pipe 21 and the charger-side pipe 22.

[0056] This allows cooling water to be supplied to electrical equipment that requires cooling according to the three modes, and by using only a portion of cooling pipe 18 according to the mode, the distance that cooling water flows can be shortened. As a result, the resistance (pipe resistance) when cooling water flows through cooling pipe 18 is reduced, and the cooling efficiency of the target electrical equipment can be improved. Furthermore, because the amount of cooling water used to cool the electrical equipment can be reduced, for example, motor-side cooling water pump 23 and charger-side cooling water pump 24 can be made smaller, and the diameter of cooling pipe 18 can be made smaller (thinner pipes can be used), thereby reducing the cost required for cooling equipment.

[0057] In the charging mode, the controller 27 controls the motor side switching valve 25 and the charger side switching valve 26 so that the cooling water cooled by the radiator 16 flows into the charger side pipe 22, in the internal power mode, the controller 27 controls the motor side switching valve 25 and the charger side switching valve 26 so that the cooling water cooled by the radiator 16 flows into the motor side pipe 21, and in the external power mode, the controller 27 controls the motor side switching valve 25 and the charger side switching valve 26 so that the cooling water cooled by the radiator 16 flows into the charger side pipe 22 and the motor side pipe 21.

[0058] This allows only the charger 14 to be cooled in the charging mode, only the electric motor 10 and the inverter 13 to be cooled in the internal power mode, and the electric motor 10, the inverter 13, and the charger 14 to be cooled in the external power mode.

[0059] The cooling water pump includes a motor-side cooling water pump 23 provided in the motor-side pipe 21 and a charger-side cooling water pump 24 provided in the charger-side pipe 22. Therefore, the motor-side cooling water pump 23 only needs to have an output that is sufficient to supply cooling water for cooling only the electric motor 10 and the inverter 13, which are electrical equipment that requires cooling. Also, the charger-side cooling water pump 24 only needs to have an output that is sufficient to supply cooling water for cooling only the charger 14, which is electrical equipment that requires cooling.

[0060] Therefore, compared to when cooling water is supplied by a single cooling water pump, the motor-side cooling water pump 23 and the charger-side cooling water pump 24 can be made smaller and the amount of cooling water discharged can be kept small. As a result, the motor-side cooling water pump 23 and the charger-side cooling water pump 24 require less space for installation, so they can be mounted on small hydraulic excavators (for example, hydraulic excavators with a total weight of less than 8 tons) where it is difficult to secure installation space.

[0061] Furthermore, the motor-side cooling water pump 23 and the charger-side cooling water pump 24 can stabilize the amount of cooling water discharged, thereby enabling stable cooling of the electrical equipment to be cooled. In particular, the charger-side cooling water pump 24 can stably supply cooling water to the charger 14, which needs to be kept at a low temperature, thereby extending the life of the charger 14. Furthermore, the motor-side cooling water pump 23 and the charger-side cooling water pump 24 can keep power consumption low by stabilizing the amount of cooling water discharged, enabling energy savings in the electric hydraulic excavator 1.

[0062] The switching valve includes a motor-side switching valve 25 provided in the motor-side pipe 21, and a charger-side switching valve 26 provided in the charger-side pipe 22. This allows the motor-side switching valve 25 and the charger-side switching valve 26 to be formed using general two-way, two-position solenoid valves, which also contributes to cost reduction.

[0063] In the embodiment, the switching valve is configured by the motor-side switching valve 25 and the charger-side switching valve 26. However, the present invention is not limited to this, and for example, a configuration may be adopted in which one three-way, three-position switching valve is provided at the other end of the outlet pipe 19 of the cooling pipe 18, and cooling water is supplied to one or both of the motor-side pipe 21 and the charger-side pipe 22.

[0064] In the embodiment, an electric hydraulic excavator 1 equipped with a crawler-type undercarriage 2 is exemplified. However, the present invention is not limited to this, and can be applied to other electric construction machines, such as an electric hydraulic excavator equipped with a wheel-type undercarriage. [Explanation of symbols]

[0065] 1 Electric hydraulic excavator 2 Undercarriage (car body) 4 Upper rotating body (car body) 6. Work equipment 6E Boom cylinder (hydraulic actuator) 6F Arm cylinder (hydraulic actuator) 6G Bucket cylinder (hydraulic actuator) 10 Electric motor 11 Hydraulic pump 12 Battery device 13 Inverter 14 Charger 16 Radiator 18 Cooling pipe line 19 Outlet pipe 20 Inlet pipe 21 Motor side pipe 22 Charger side conduit 23 Motor side cooling water pump (cooling water pump) 24 Charger side cooling water pump (cooling water pump) 25 Motor side switching valve (switching valve) 26 Charger side switching valve (switching valve) 27 Controller 28 Commercial power supply (external power supply)

Claims

1. Equipped with a self-propelled vehicle body, The vehicle body is an electric motor as a power source; a battery device that stores power to be supplied to the electric motor; a charger that is connected to an external power source to convert power from the external power source and supply the converted power to the battery device; a radiator that cools the cooling water; a cooling pipe line that connects the radiator to the electric motor and the charger; a cooling water pump that supplies cooling water cooled by the radiator to the cooling pipe; a controller for controlling the flow of cooling water cooled by the radiator; In an electric construction machine equipped with the cooling pipe includes a motor-side pipe connecting the radiator and the electric motor, and a charger-side pipe connecting the radiator and the charger, a switching valve is provided in the cooling pipe line to switch the supply destination of the cooling water cooled by the radiator to one or both of the motor-side pipe line and the charger-side pipe line; the switching valve includes a normally closed motor-side switching valve provided in the motor-side pipe line and a normally closed charger-side switching valve provided in the charger-side pipe line, The controller In a charging mode in which the battery device is charged with the external power supply connected to the charger, the charger-side switching valve is opened so that the coolant cooled by the radiator flows into the charger-side pipe, In an internal power mode in which the electric motor is driven by the electric power stored in the battery device, the motor-side switching valve is opened so that the coolant cooled by the radiator flows into the motor-side pipe line; an external power mode in which the electric motor is driven by power from the external power source and surplus power is charged to the battery device, and the charger-side selector valve and the motor-side selector valve are opened so that cooling water cooled by the radiator flows into the charger-side pipe and the motor-side pipe.

2. The electric construction machine according to claim 1, An electric construction machine, characterized in that the vehicle body is capable of traveling in the internal power mode and the external power mode.

3. The electric construction machine according to claim 1, an electric construction machine, wherein the cooling water pump comprises a motor-side cooling water pump provided in the motor-side pipe; and a charger-side cooling water pump provided in the charger-side pipe.

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