Battery-powered work machine

Abstract

To reduce power consumption of a battery-powered work machine.SOLUTION: An electric shovel includes a main body, a battery 37 provided in the main body and whose temperature is regulated by a temperature control fluid, an electric motor 40 driven by power from the battery 37, a hydraulic pump 43 driven by the electric motor 40, and a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump 43. When the temperature of the hydraulic oil is higher than the temperature of the temperature control fluid, the electric shovel heats the battery 37 with the hydraulic oil.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to battery powered work machines. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 11-229430 (Patent Document 1) discloses a battery-powered hydraulic excavator. A battery mounted on an upper rotating body supplies power to an electric motor, which drives a hydraulic pump, and the hydraulic actuator is operated by the flow rate discharged from the hydraulic pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-229430 Summary of the Invention [Problem to be solved by the invention]

[0004] When warming up a battery-powered work machine in cold regions, it is necessary to warm up the battery in addition to the hydraulic oil. However, because the energy source for warming up is electricity from the battery, electricity consumption is reduced and the continuous operating time of the work machine is shortened.

[0005] The present disclosure proposes a battery-powered work machine that can reduce power consumption. [Means for solving the problem]

[0006] A battery-powered work machine according to the present disclosure includes a main body, an electricity storage device provided in the main body and temperature-regulated by a temperature control fluid, an electric motor driven by electric power from the electricity storage device, a hydraulic pump driven by the electric motor, and a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump. The battery-powered work machine heats the electricity storage device with the hydraulic oil when the temperature of the hydraulic oil is higher than the temperature of the temperature control fluid. Effect of the Invention

[0007] According to the battery-powered work machine of the present disclosure, power consumption can be reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an electric shovel. [Diagram 2] FIG. 2 is a block diagram showing a system configuration of the electric shovel shown in FIG. [Diagram 3] FIG. 2 is a perspective view showing a schematic configuration of a battery. [Figure 4] 5 is a flowchart showing a flow of a process for adjusting the temperature of a battery. [Diagram 5] FIG. 11 is a schematic diagram showing another example of the arrangement of the heat exchanger. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. It is also intended from the beginning that any configuration may be extracted from the embodiments and that they may be combined in any desired manner.

[0010] In the following description, the terms "up," "down," "front," "rear," "left," and "right" are directions based on the operator seated in the driver's seat 4S in the driver's cab 4.

[0011] <Work machine configuration> Fig. 1 is a perspective view showing a schematic configuration of an electric shovel 100 as an example of a battery-powered work machine in an embodiment. As shown in Fig. 1, the electric shovel 100 has a main body 1 and a work machine 2 that operates hydraulically. The main body 1 has a rotating body 3 and a traveling body 5.

[0012] The traveling body 5 has a pair of tracks 5Cr and a traveling motor 5M. The electric excavator 100 can travel by rotation of the tracks 5Cr. The traveling motor 5M is provided as a drive source for the traveling body 5. The traveling motor 5M is a hydraulic motor that is hydraulically operated. The traveling body 5 may have wheels (tires).

[0013] The rotating body 3 is disposed on the running body 5 and is supported by the running body 5. The rotating body 3 can be rotated relative to the running body 5 about a rotation axis RX by a rotation motor 24 (FIG. 2). The rotation motor 24 is a hydraulic motor that is hydraulically operated. The traveling motor 5M or the rotation motor 24 may be an electric motor. The rotation axis RX is an imaginary straight line that serves as the rotation center of the rotating body 3.

[0014] The rotating body 3 has a driver's cab 4 (cab). The driver's cab 4 is disposed, for example, on the front left side (vehicle front side) of the rotating body 3. A driver's seat 4S in which an operator sits is provided inside the driver's cab 4. The operator (crew member) gets into the driver's cab 4 and can operate the work equipment 2, rotate the rotating body 3 relative to the running body 5, and travel the electric excavator 100 using the running body 5.

[0015] The rotating body 3 has an exterior cover 9. The exterior cover 9 covers a machine room. The machine room is disposed on the rear side of the rotating body 3 (the rear side of the vehicle) with respect to the driver's cab 4. In the machine room, a battery 37, an inverter 31, an electric motor 40, a hydraulic pump 43, a swing motor 24, a main valve 41, a hydraulic oil tank 42 (all see FIG. 2), and the like are disposed.

[0016] The work machine 2 is supported by the rotating body 3 on the front side of the rotating body 3, for example, to the right of the operator's cab 4. The work machine 2 has a boom 6, an arm 7, and a bucket 8.

[0017] The boom 6 is rotatably connected to the main body 1. Specifically, the base end of the boom 6 is rotatably connected to the rotating body 3 with a boom foot pin 13 as a fulcrum. The arm 7 is rotatably connected to the boom 6. Specifically, the base end of the arm 7 is rotatably connected to the tip of the boom 6 with a boom top pin 14 as a fulcrum. The bucket 8 is rotatably connected to the arm 7. Specifically, the base end of the bucket 8 is rotatably connected to the tip of the arm 7 with an arm top pin 15 as a fulcrum.

[0018] The boom 6 can be driven relative to the main body 1 by a boom cylinder 10. This drive allows the boom 6 to rotate vertically relative to the rotating structure 3, with a boom foot pin 13 as a fulcrum. One end of the boom cylinder 10 is connected to the rotating structure 3, and the other end is connected to the boom 6.

[0019] The arm 7 can be driven relative to the boom 6 by an arm cylinder 11. This drive allows the arm 7 to rotate up and down or back and forth relative to the boom 6, with the boom top pin 14 as a fulcrum. One end of the arm cylinder 11 is connected to the boom 6, and the other end is connected to the arm 7.

[0020] The bucket 8 can be driven relative to the arm 7 by a bucket cylinder 12. This drive allows the bucket 8 to rotate vertically relative to the arm 7 with an arm top pin 15 as a fulcrum. One end of the bucket cylinder 12 is connected to the arm 7, and the other end is connected to a bucket link 17.

[0021] Each of the boom cylinder 10, the arm cylinder 11 and the bucket cylinder 12 is a hydraulic cylinder and is driven by hydraulic pressure.

[0022] <System configuration> Fig. 2 is a block diagram showing a system configuration of the electric shovel 100 shown in Fig. 1. The electric shovel 100 is equipped with an electric motor 40 as a power source. In the electric shovel 100, the electric motor 40 generates driving force for driving the work machine 2. The electric motor 40 is capable of driving the work machine 2. The boom 6, the arm 7, and the bucket 8 are each driven by the electric motor 40, thereby enabling the work machine 2 to operate.

[0023] The electric motor 40 is driven by AC power supplied from the inverter 31 using the battery 37 as a power source. The rotation speed of the electric motor 40 is controlled by the frequency of the AC power supplied from the inverter 31.

[0024] The battery 37 is disposed in a machine room covered with an exterior cover 9 shown in FIG. 1, and is provided in the main body 1 (revolving body 3) of the electric excavator 100. The battery 37 is disposed at the rear end of the revolving body 3. The battery 37 is mounted on the revolving body 3. The battery 37 is supported by a frame of the revolving body 3.

[0025] The battery 37 is a power storage device that stores electric energy. The battery 37 extracts the stored electric energy as electromotive force. The battery 37 is, for example, a secondary battery such as a lithium ion battery or a nickel-metal hydride battery. The battery 37 includes, for example, a plurality of battery packs. Each of the plurality of battery packs has a plurality of battery cells. The battery cell is formed, for example, by stacking a positive electrode and a negative electrode with a separator interposed therebetween.

[0026] The temperature sensor 39 detects the temperature of the battery 37. Data on the temperature of the battery 37 detected by the temperature sensor 39 is input to the controller 30.

[0027] The inverter 31 converts the DC current output from the battery 37 into an AC current with controlled frequency, etc. The inverter 31 supplies AC power to the electric motor 40 through electrical wiring. The inverter 31 controls the driving of the electric motor 40 in accordance with a control signal input from the controller 30. The electric energy stored in the battery 37 in this manner is supplied to the electric motor 40.

[0028] The electric shovel 100 drives the electric motor 40 with electricity stored in a battery 37. The electric shovel 100 is equipped with a large-capacity battery 37. The electric shovel 100 does not have an engine. The battery-powered electric shovel 100 can work without emitting carbon dioxide, and can reduce vibration and noise during work.

[0029] The battery 37 and the inverter 31 are electrically connected via a power distribution unit (PDU) 35 and a high voltage junction box (HVJB) 36. The power distribution unit 35 has a function of distributing the power stored in the battery 37 to each device including the inverter 31. The high voltage junction box 36 is connected to the battery 37 and also to a charging port 38. An external power source or an external generator is connected to the charging port 38 to charge the battery 37. The battery 37 stores electrical energy obtained from an external source.

[0030] The inverter 31, the power distribution unit 35, the high-voltage junction box 36, the battery 37, the charging port 38, and the electric motor 40 are connected by high-voltage wiring. The battery 37 supplies power to the inverter 31 through the high-voltage wiring. The inverter 31, the power distribution unit 35, the high-voltage junction box 36, and the high-voltage wiring connecting them together form an electric circuit electrically connected to the battery 37.

[0031] An output shaft of the electric motor 40 is mechanically connected to an input shaft of the hydraulic pump 43. When the electric motor 40 is driven, the driving force of the electric motor 40 is transmitted to the hydraulic pump 43, and the hydraulic pump 43 is driven.

[0032] The hydraulic oil tank 42 stores hydraulic oil therein and serves to supply hydraulic oil to the hydraulic pump 43. The hydraulic pump 43 pumps hydraulic oil from the hydraulic oil tank 42 when driven. A hydraulic pipe 44 is connected to the hydraulic pump 43. The tip of the hydraulic pipe 44 is immersed in the hydraulic oil in the hydraulic oil tank 42. A filter 45 is attached to the tip of the hydraulic pipe 44. The hydraulic oil in the hydraulic oil tank 42 passes through the filter 45 and flows into the hydraulic pipe 44, and is sucked into the hydraulic pump 43.

[0033] The hydraulic oil discharged from the hydraulic pump 43 is supplied to the main valve 41 through hydraulic piping 44. The main valve 41 is disposed in an oil passage between the hydraulic pump 43 and the hydraulic actuator. The main valve 41 is configured as an assembly of a number of control valves, pilot valves, etc. The main valve 41 supplies and discharges the hydraulic oil pumped out from the hydraulic oil tank 42 by the drive of the hydraulic pump 43 to the hydraulic actuator.

[0034] The hydraulic actuator includes a swing motor 24 in addition to the boom cylinder 10, arm cylinder 11, bucket cylinder 12, and traveling motor 5M also shown in Fig. 1. The swing motor 24 and traveling motor 5M are hydraulically driven hydraulic motors.

[0035] The opening and closing of each valve in the main valve 41 is controlled in response to the operation of an operator in the operator's cab 4 (FIG. 1). The main body 1 and the work unit 2 of the electric shovel 100 can be operated in response to the driving operation of the operator. Specifically, the operator can operate the work unit 2 by operating the hydraulic cylinders 10, 11, and 12, can operate the rotation of the rotating body 3 relative to the traveling body 5 by operating the swing motor 24, and can operate the traveling of the electric shovel 100 by operating the traveling motor 5M.

[0036] The hydraulic oil discharged from the hydraulic actuator is returned to the hydraulic oil tank 42 via the main valve 41 and hydraulic piping 46. The hydraulic oil flowing from the hydraulic actuator to the hydraulic oil tank 42 flows through the hydraulic piping 46.

[0037] An air-cooled radiator 47 is provided in the hydraulic piping 46. The air-cooled radiator 47 includes a heat exchanger, a fan for blowing air to the heat exchanger, and a motor for driving the fan. In the heat exchanger, heat is exchanged between the hydraulic oil and the airflow supplied by the fan, and the hydraulic oil is cooled by dissipating heat into the air.

[0038] A relief valve 48 is provided in the hydraulic pipe 46. The relief valve 48 regulates the maximum pressure of the hydraulic pipe 46 by providing relief when the pressure of the hydraulic oil in the hydraulic pipe 46 reaches or exceeds a set pressure.

[0039] The temperature sensor 49 detects the temperature of the hydraulic oil flowing through the hydraulic piping 46. A bypass piping 50 branches off from the hydraulic piping 46. The temperature sensor 49 detects the temperature of the hydraulic oil upstream of the branch point with the bypass piping 50. The temperature sensor 49 detects the temperature of the hydraulic oil immediately downstream of the main valve 41 in the path of the hydraulic oil heading from the hydraulic actuator to the hydraulic oil tank 42.

[0040] The bypass pipe 50 is provided with a switching valve 51. The switching valve 51 switches between opening and closing the bypass pipe 50. When the switching valve 51 opens the bypass pipe 50, a portion of the hydraulic oil flowing from the hydraulic actuator to the hydraulic oil tank 42 branches off from the hydraulic pipe 46 and flows into the bypass pipe 50. When the switching valve 51 closes the bypass pipe 50, the hydraulic oil stops flowing into the bypass pipe 50.

[0041] The main valve 41, the hydraulic oil tank 42, the hydraulic pipes 44, 46 and the bypass pipe 50 constitute a hydraulic oil circuit through which the hydraulic oil flows.

[0042] The bypass pipe 50 is provided with a heat exchanger 52. The heat exchanger 52 exchanges heat between the hydraulic oil flowing through the bypass pipe 50 and the temperature control fluid flowing through the fluid pipe 64. The temperature control fluid is a fluid, such as water.

[0043] 2 is disposed between the battery 37 and the battery thermal management system 60. The temperature control fluid flowing through the fluid pipe 64 circulates between the battery 37 and the battery thermal management system 60. The temperature of the battery 37 is controlled by the temperature control fluid. When the battery 37 is at a low temperature, heat is transferred from the temperature control fluid to the battery 37, thereby warming the battery 37. When the battery 37 is at a high temperature, heat is dissipated from the battery 37 to the temperature control fluid, thereby cooling the battery 37.

[0044] The battery thermal management system 60 has a heater 61 and a chiller 62. The battery thermal management system 60 has both a function of heating a temperature control fluid and a function of cooling the temperature control fluid. The heater 61 is, for example, an electric heater. The temperature control fluid is heated by the heat generated by the heater 61. The chiller 62 is, for example, an evaporator that constitutes a refrigeration cycle. The chiller 62 cools the temperature control fluid.

[0045] The battery thermal management system 60 has a switching valve 63. The switching valve 63 switches the flow of the temperature control fluid. The switching valve 63 is provided in a bypass path that bypasses the fluid piping 64 in the battery thermal management system 60. By closing the switching valve 63, a flow of the temperature control fluid is generated from the battery thermal management system 60 toward the heat exchanger 52. By opening the switching valve 63, the flow of the temperature control fluid toward the heat exchanger 52 is suppressed.

[0046] The battery thermal management system 60 has a pump 65. The pump 65 generates power to circulate the temperature control fluid through the fluid piping 64. The battery thermal management system 60 controls the temperature of the battery 37 by circulating the temperature control fluid heated by the heater 61 or cooled by the chiller 62 through the battery 37. The temperature sensor 69 detects the temperature of the temperature control fluid discharged from the pump 65. The temperature sensor 69 detects the temperature of the temperature control fluid before the temperature is controlled by the battery thermal management system 60.

[0047] The controller 30 includes a CPU (Central Processing Unit), a memory, and the like. The memory stores a program for controlling the operation of the electric shovel 100 and various data required for executing the program. The memory also temporarily stores working data generated in association with the operation of the electric shovel 100. The controller 30 controls the operation of the electric shovel 100 by executing the control program stored in the memory.

[0048] The controller 30 sends a control signal to the switching valve 51 to control the opening of the switching valve 51. Data on the temperature of the hydraulic oil detected by the temperature sensor 49 is input to the controller 30. The controller 30 sends a control signal to the switching valve 63 to control the opening of the switching valve 63. Data on the temperature of the temperature control fluid detected by the temperature sensor 69 is input to the controller 30. The controller 30 appropriately operates the heater 61 or the chiller 62 based on the detection result of the temperature sensor 69. This allows the temperature of the temperature control fluid supplied from the battery thermal management system 60 to the battery 37 to be appropriately controlled.

[0049] <Temperature control of power storage device> Fig. 3 is a perspective view showing a schematic configuration of battery 37. Battery 37 includes a plurality of battery packs 37A-37F. The plurality of battery packs 37A-37F are stacked in the vertical direction. Although six battery packs 37A-37F are shown in Fig. 3, the number of battery packs constituting battery 37 is of course arbitrary.

[0050] Each of the battery packs 37A to 37F is provided with a supply port and a return port. The battery pack 37A has a supply port 37AS and a return port 37AR. The battery pack 37F has a supply port 37FS and a return port 37FR. A fluid pipe 64 is connected to the supply port of each of the battery packs 37A to 37F. A fluid pipe 64 is connected to the return port of each of the battery packs 37A to 37F.

[0051] The temperature control fluid is supplied to each of the battery packs 37A-37F from the fluid piping 64 via the supply port. The temperature control fluid flows inside each of the battery packs 37A-37F to control the temperature of each battery cell included in the battery 37. After being used to control the temperature of the battery 37, the temperature control fluid flows out of each of the battery packs 37A-37F via the return port and is returned to the fluid piping 64.

[0052] Fig. 4 is a flowchart showing the flow of a process for adjusting the temperature of the battery 37. The process in each step shown in Fig. 4 is executed by the controller 30 (Fig. 2).

[0053] In step S1, the controller 30 determines whether the temperature of the hydraulic oil is higher than the target temperature of the temperature adjustment fluid. The temperature of the hydraulic oil is the temperature of the hydraulic oil flowing through the hydraulic piping 46 after being used to operate the hydraulic actuator. The temperature of the hydraulic oil is detected by the temperature sensor 49 and input to the controller 30. The target temperature of the temperature adjustment fluid is stored in the memory of the controller 30. The controller 30 compares the inputted temperature of the hydraulic oil with the target temperature of the temperature adjustment fluid read from the memory, and determines whether the temperature of the hydraulic oil is higher than the target temperature of the temperature adjustment fluid.

[0054] If it is determined that the temperature of the hydraulic oil is higher than the target temperature of the temperature control fluid (YES in step S1), in step S2, the controller 30 determines whether the environmental temperature is equal to or lower than a threshold value. In this case, the environmental temperature includes at least one of the outside air temperature, the temperature of the battery 37, and the temperature of the temperature control fluid. The environmental temperature threshold value is stored in the memory of the controller 30. The environmental temperature threshold value is, for example, the lower limit value of the operating temperature range of the battery 37.

[0055] The controller 30 compares the input environmental temperature with the environmental temperature threshold value read from the memory to determine whether the environmental temperature is equal to or lower than the threshold value. The controller 30 determines whether the temperature of the battery 37 is equal to or lower than a predetermined temperature, or whether the temperature of the temperature control fluid is equal to or lower than a predetermined temperature.

[0056] If it is determined that the environmental temperature is equal to or lower than the threshold value (YES in step S2), in step S3, the controller 30 executes a process of heating the temperature control fluid with the hydraulic oil. The controller 30 controls the aperture of the switching valve 51 to generate a flow of hydraulic oil returning to the hydraulic oil tank 42 via the bypass piping 50. In addition, the controller 30 controls the aperture of the switching valve 63 to generate a flow of temperature control fluid toward the heat exchanger 52. In the heat exchanger 52, heat is transferred from the high-temperature hydraulic oil to the low-temperature temperature control fluid, and the temperature of the temperature control fluid increases.

[0057] The temperature control fluid, whose temperature has increased due to the heat of the hydraulic oil, is supplied to the battery 37, whereby the battery 37 can be heated by the temperature control fluid. Since the temperature control fluid is heated by the hydraulic oil, the amount of heat generated by the heater 61 required to heat the temperature control fluid to a temperature appropriate for heating the battery 37 can be reduced. This makes it possible to suppress the power consumption of the heater 61.

[0058] If the temperature of the hydraulic oil is equal to or lower than the target temperature of the temperature control fluid (NO in step S1), the temperature control fluid cannot be heated by the hydraulic oil, so the process proceeds to step S4, and the process of heating the temperature control fluid by the hydraulic oil is not executed. If the temperature of the battery 37 is higher than a predetermined temperature (NO in step S2), there is no need to heat the battery 37 by the temperature control fluid, so the process proceeds to step S4, and the process of heating the temperature control fluid by the hydraulic oil is not executed. If the temperature of the temperature control fluid for adjusting the temperature of the battery 37 is higher than a predetermined temperature and the temperature control fluid is sufficiently heated (NO in step S2), the process proceeds to step S4, and the process of heating the temperature control fluid by the hydraulic oil is not executed.

[0059] In the judgment of step S1, it may be judged that the temperature difference between the hydraulic oil and the temperature control fluid is equal to or greater than a predetermined value. Even if the temperature of the hydraulic oil is higher than the target temperature of the temperature control fluid, if the temperature difference is small, the amount of heat transferred from the hydraulic oil to the temperature control fluid cannot be increased sufficiently, and it may be difficult to efficiently heat the temperature control fluid. If the temperature control fluid is heated with hydraulic oil that is sufficiently higher in temperature than the temperature control fluid, the temperature control fluid can be efficiently heated.

[0060] Fig. 5 is a schematic diagram showing another example of the arrangement of the heat exchanger 52. The heat exchanger 52 can be arranged at any position in the hydraulic oil circuit through which the hydraulic oil flows, as long as the heat exchanger 52 can exchange heat between the hydraulic oil and the temperature control fluid. As shown in Fig. 5, the heat exchanger 52 may be arranged inside the hydraulic oil tank 42.

[0061] The controller 30 transmits a control signal to the switching valve 63 to control the opening degree of the switching valve 63. By opening the switching valve 63 shown in Fig. 5, a flow of temperature control fluid toward the heat exchanger 52 is generated, and the temperature control fluid can be heated by the hydraulic oil. By closing the switching valve 63 shown in Fig. 5, the flow of temperature control fluid toward the heat exchanger 52 can be suppressed.

[0062] In the above embodiment, the electric shovel 100 is given as an example of a work machine, but the present invention is not limited to the electric shovel 100 and can be applied to other types of work machines equipped with a battery 37 (electricity storage device). For example, the work machine may be other types of battery-powered work machines, such as an electric wheel loader, an electric bulldozer, or an electric dump truck.

[0063] <Action and Effects> Although some of the description herein overlaps with the above description, the characteristic configuration and effects of this embodiment can be summarized as follows.

[0064] As shown in FIG. 4, when the temperature of the hydraulic oil is higher than the temperature of the temperature control fluid that adjusts the temperature of the battery 37, the battery 37 is heated by the hydraulic oil. In the electric excavator 100 equipped with a hydraulic actuator, the hydraulic oil receives a large amount of heat when the hydraulic actuator is driven, and the hydraulic oil is likely to become hot. The heat of the hydraulic oil can be used to keep the battery 37 warm. The exhaust heat of the hydraulic oil after driving the hydraulic actuator can be diverted to warm the battery 37 to heat the battery 37. The amount of heat generated by the heater 61 for heating the temperature control fluid can be reduced, and if the temperature control fluid can be heated to a target temperature or higher by the hydraulic oil, it is not necessary to operate the heater 61, so the power consumption of the heater 61 can be suppressed. The electric excavator 100 can be operated continuously even in cold regions.

[0065] As shown in Fig. 4, when the temperature of the battery 37 or the temperature of the temperature control fluid is equal to or lower than a predetermined temperature, the battery 37 may be heated with hydraulic oil. The battery 37 has an operating temperature range (for example, 15°C or higher and 35°C or lower), and the battery 37 may deteriorate in a temperature range lower than the lower limit of the operating temperature range. When the battery 37 is equal to or lower than a predetermined temperature, or when the temperature control fluid that controls the temperature of the battery 37 is equal to or lower than a predetermined temperature, the battery 37 can be heated with hydraulic oil that is hotter than the temperature control fluid. This allows the battery 37 to be heated to the operating temperature range quickly while suppressing power consumption.

[0066] As shown in Figs. 2 and 5, a heat exchanger 52 for exchanging heat between the hydraulic oil and the temperature control fluid may be provided in the hydraulic oil circuit through which the hydraulic oil flows. To heat the battery 37 with the hydraulic oil, the hydraulic oil may be circulated through the battery 37 to directly transfer heat from the hydraulic oil to the battery 37. In that case, a refrigerant path for cooling the battery 37 is required in addition to the hydraulic oil path for heating the battery 37. In a battery-powered electric working machine, the battery 37 has a large capacity and contains a large number of battery packs (battery cells). Therefore, if a hydraulic oil path and a refrigerant path are provided for temperature control for all battery cells, the structure becomes complicated, and it is difficult to realize in terms of space limitations and costs. By exchanging heat between the hydraulic oil and the temperature control fluid in the heat exchanger 52 and supplying the temperature control fluid warmed by the heat of the hydraulic oil to the battery 37, a structure for heating the battery 37 with the hydraulic oil can be easily realized.

[0067] 2, a heat exchanger 52 may be provided in a bypass pipe 50 through which hydraulic oil flows from the hydraulic actuator to the hydraulic oil tank 42. This makes it possible to increase the temperature of the temperature control fluid by using high-temperature hydraulic oil after driving the hydraulic actuator.

[0068] As shown in Fig. 5, the heat exchanger 52 may be disposed inside the hydraulic oil tank 42. This makes it possible to increase the temperature of the temperature control fluid by using high-temperature hydraulic oil that has been returned to the hydraulic oil tank 42 after driving the hydraulic actuator. Since the heat exchanger 52 can be disposed without providing the bypass piping 50 shown in Fig. 2, the configuration can be simplified, space can be saved, and energy for transporting the hydraulic oil via the bypass piping 50 can be eliminated.

[0069] 3, the battery 37 may include a plurality of stacked battery packs 37A to 37F, and a temperature regulating fluid may flow inside each of the plurality of battery packs 37A to 37F. In this way, the temperature of each of the plurality of battery packs 37A to 37F can be regulated to an appropriate temperature.

[0070] The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0071] 1 main body, 2 work machine, 3 rotating body, 5 traveling body, 5M traveling motor, 6 boom, 7 arm, 8 bucket, 10 boom cylinder, 11 arm cylinder, 12 bucket cylinder, 24 rotating motor, 30 controller, 31 inverter, 35 power distribution unit, 36 high-pressure junction box, 37 battery, 37A to 37F battery pack, 37AR, 37FR return port, 37AS, 37FS supply port, 38 charging port, 39, 49, 69 temperature sensor, 40 electric motor, 41 main valve, 42 hydraulic oil tank, 43 hydraulic pump, 44, 46 hydraulic piping, 50 bypass piping, 51, 63 switching valve, 52 heat exchanger, 60 battery thermal management system, 61 heater, 62 chiller, 64 fluid piping, 65 pump, 100 electric excavator.

Claims

1. The main body, a power storage device provided in the main body and temperature-controlled by a temperature control fluid; an electric motor driven by power from the power storage device; a hydraulic pump driven by the electric motor; a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump, The battery-powered working machine, wherein the power storage device is heated by the hydraulic oil when the temperature of the hydraulic oil is higher than the temperature of the temperature control fluid.

2. 2. The battery-powered working machine according to claim 1, wherein when the temperature of the power storage device or the temperature control fluid is equal to or lower than a predetermined temperature, the power storage device is heated by the hydraulic oil.

3. 3. The battery-powered working machine according to claim 1, further comprising a heat exchanger provided in a hydraulic oil circuit through which the hydraulic oil flows, for exchanging heat between the hydraulic oil and the temperature control fluid.

4. The hydraulic oil circuit includes a hydraulic oil tank in which the hydraulic oil is stored, 4. The battery-powered work machine according to claim 3, wherein the heat exchanger is provided in the hydraulic oil circuit through which the hydraulic oil flows from the hydraulic actuator to the hydraulic oil tank.

5. The hydraulic oil circuit includes a hydraulic oil tank in which the hydraulic oil is stored, The battery-powered work machine according to claim 3 , wherein the heat exchanger is disposed inside the hydraulic oil tank.

6. The power storage device includes a plurality of stacked battery packs, The battery-powered work machine of claim 3 , wherein the temperature regulating fluid flows within each of the plurality of battery packs.

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