Electrically-driven type work machine

Abstract

To provide an electrically-driven type work machine such that a hydrogen gas hardly stagnates in a vehicle body even when a fuel battery is mounted.SOLUTION: An electrically-driven type work machine comprises: a fuel battery 21; an electric motor driven with electric power supplied from the fuel battery 21; a hydrogen tank 50 reserving hydrogen to be supplied to the fuel battery 21; and a hydrogen tank-side exterior cover 90A covering the fuel battery 21, electric motor, and hydrogen tank 50, wherein the fuel battery 21 and electric motor are partitioned off from the hydrogen tank 50 by a partition member 95, and the hydrogen tank-side exterior cover 90A is provided with an opening above the hydrogen tank 50.SELECTED DRAWING: Figure 5B

Description

[Technical Field]

[0001] The present invention particularly relates to an electric work machine that is equipped with a fuel cell and operates on power supplied from the fuel cell. [Background technology]

[0002] In recent years, attempts have been made to install environmentally friendly fuel cell systems in electric work machines. Fuel cell systems are composed of a fuel cell that supplies electricity to an electric motor, which serves as a power source, and a hydrogen storage container that stores the hydrogen supplied to the fuel cell.

[0003] Patent Document 1 describes a construction machine that includes a first swivel unit that is provided between a main body and a traveling device that causes the main body to travel and that rotates the main body, a working device connected to the main body, and a storage unit that can be rotated by a second swivel unit that is different from the first swivel unit. The storage unit houses a hydrogen tank that stores hydrogen and a fuel cell that generates electricity using hydrogen supplied from the hydrogen tank, and a hydraulic device that drives the working device is disposed in the main body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-180565 Summary of the Invention [Problem to be solved by the invention]

[0005] When filling the hydrogen storage container with hydrogen, a filling nozzle of a hydrogen supply facility such as a mobile hydrogen station is connected and hydrogen gas is filled. However, improper filling procedures can result in hydrogen gas remaining inside the vehicle. While it is possible to exhaust hydrogen to the outside using a cooling fan or other means while the vehicle is in operation, all electrical systems, including the cooling fan, are shut off when the vehicle is idle (including during maintenance). Furthermore, since welding work for repairs is also included in the maintenance of electrically powered work machinery, it is undesirable for hydrogen gas to remain inside the vehicle.

[0006] An object of the present invention is to provide an electric working machine that is less likely to have hydrogen gas accumulating inside the vehicle body even when equipped with a fuel cell. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a work machine comprising a high-power system having a fuel cell and an electric motor driven by power supplied from the fuel cell, a hydrogen tank for storing hydrogen to be supplied to the fuel cell, and an exterior cover that covers the high-power system and the hydrogen tank, wherein a partition member is provided between the high-power system and the hydrogen tank, and the exterior cover has an opening at a position corresponding to the top of the hydrogen tank. In this case, it is possible to provide an electric work machine that is less likely to have hydrogen gas accumulating inside the vehicle body even when equipped with a fuel cell.

[0008] Here, for example, the hydrogen tank is provided below the opening. In this case, even if hydrogen leaks from the hydrogen tank, it can be quickly released to the outside through the opening. Furthermore, for example, the hydrogen tank is located above the high-power system, so even if hydrogen leaks, it is less likely to flow to the high-power system. Furthermore, for example, the hydrogen tank is positioned so that it overlaps the high-power system when viewed from above. In this case, the hydrogen piping can be shortened, and if the electric work machine is a hydraulic excavator, the rear radius can be reduced. Furthermore, for example, multiple hydrogen tanks can be provided side by side at approximately the same height. In this case, the overall height of the electric work machine can be reduced, and since the tanks are not far from the opening, hydrogen can be quickly released to the outside in the event of a leak. In addition, for example, a hydrogen filling port for filling the hydrogen tank is provided on the exterior cover that is separated by a partition member, so that the storage path and the high-power system can be isolated from each other during hydrogen filling. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an electric working machine in which hydrogen gas is less likely to accumulate inside the vehicle body even when a fuel cell is installed. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing the overall configuration of an electric working machine according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating a system configuration of a hydraulic excavator. [Figure 3] FIG. 2 is a left rear view of the rotating body of the hydraulic excavator according to the present embodiment. [Figure 4] FIG. 2 is a right-front view of a rotating body of the hydraulic excavator according to the present embodiment. [Figure 5A] FIG. 2 is a cross-sectional view of a rotating body. [Figure 5B] 5B is a diagram in which the position of the cross section of FIG. 5A is changed to clarify the position of the high-voltage system. [Figure 6A] FIG. [Figure 6B] 6B is a diagram in which the position of the cross section of FIG. 6A is changed to clarify the position of the high-voltage system. [Figure 7] FIG. 1 is a diagram illustrating a method for filling a hydraulic excavator with hydrogen. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0012] <Explanation of the overall configuration of the electric work machine> FIG. 1 is a diagram showing the overall configuration of an electric working machine according to this embodiment. The electric work machine shown in the figure is a hydraulic excavator 100. However, the electric work machine is not limited to this and can be a construction machine such as a wheel loader, bulldozer, or crane truck. The electric work machine can also be an agricultural machine such as a felling machine, lumbering machine, tractor, forestry work vehicle, or logging machine.

[0013] The hydraulic excavator 100 comprises a running body 3 having a pair of left and right tracks 1, 2, a rotating body 4 mounted on the running body 3, a boom 5 rotatably connected to one end of the rotating body 4 by a pin, an arm 6 rotatably connected to one end of the boom 5 by a pin, and a bucket 7 rotatably connected to one end of the arm 6 by a pin. Furthermore, the hydraulic excavator 100 is equipped with an operator's cab 8 provided on the rotating body 4, a machine room 9 that houses an electric motor 23 and a main pump 31 (see FIG. 2 ), which will be described later, a counterweight 10, travel motors 11 and 12 that drive the tracks 1 and 2, a pair of left and right boom cylinders 14 and 15 that drive the boom 5, an arm cylinder 16 that drives the arm 6, and a bucket cylinder 17 that drives the bucket 7. At this time, the main working arm corresponds to the boom 5, arm 6 and bucket 7, and the posture of these working arm mechanisms is determined by the extension and contraction of the boom cylinders 14, 15, arm cylinder 16 and bucket cylinder 17, respectively.

[0014] FIG. 2 is a diagram showing the system configuration of the hydraulic excavator 100. Since the traveling motors 11, 12 and the swing motor 13 all have the same configuration as hydraulic motors, the following description will take the swing motor 13 as an example, and omit the description of the traveling motors 11, 12. Similarly, since the boom cylinders 14, 15, the arm cylinder 16, and the bucket cylinder 17 all have the same configuration as hydraulic cylinders, the following description will take the arm cylinder 16 as an example, and omit the description of the boom cylinders 14, 15 and the bucket cylinder 17. Therefore, Fig. 2 shows only the hydraulic circuit configuration related to the arm cylinder 16 and the swing motor 13, and does not show the other hydraulic actuators.

[0015] The hydraulic excavator 100 has a system configuration including a high-voltage system 20 that operates the electric equipment, a hydraulic circuit 30 that generates hydraulic pressure, an operating system 40 that performs operations to control the operation of the high-voltage system 20 and the hydraulic circuit 30, a hydrogen tank 50 that stores hydrogen to be supplied to the fuel cell 21, and a low-voltage circuit 60 that is a low-voltage power circuit.

[0016] The hydraulic circuit 30 includes a main pump 31, a pilot pump 32, a hydraulic oil tank 33 for storing hydraulic oil, a swing motor 13 for driving the swing body 4, a first directional control valve 34 for controlling the flow of hydraulic oil related to the swing motor 13, and a second directional control valve 35 for controlling the flow of hydraulic oil related to the arm cylinder 16. The main pump 31 is a variable displacement hydraulic pump driven by the electric motor 23. This main pump 31 draws hydraulic oil from a hydraulic oil tank 33 and supplies the hydraulic oil to the swing motor 13 and the arm cylinder 16 via a first directional control valve 34 and a second directional control valve 35. Note that in this embodiment, a variable displacement hydraulic pump is used as the main pump 31, but this is not limiting, and a fixed displacement hydraulic pump may also be used. The pilot pump 32 is a fixed displacement hydraulic pump driven by the electric motor 23. This pilot pump 32 draws hydraulic oil from a hydraulic oil tank 33 and supplies it to a pair of pressure receiving chambers 34A, 34B of the first directional control valve 34 and a pair of pressure receiving chambers 35A, 35B of the second directional control valve 35, respectively. The hydraulic circuit 30 further includes a main relief valve 36 that determines the upper limit of the discharge pressure of the main pump 31, a pilot relief valve 37 that determines the upper limit of the discharge pressure of the pilot pump 32, and an on-off valve 38 that opens and closes the pipeline between the second directional control valve and the hydraulic oil tank 33.

[0017] In the operator's cab 8, an operation system 40 is provided, which includes a work mode selection switch 41, a motor control dial 42 for setting the rotation speed of the electric motor 23 (described later), operation levers 43A and 43B, and a vehicle controller 45. The control levers 43A, 43B correspond to the respective swing motors 13 and arm cylinders 16, and may be, for example, electric levers that output an electric control signal (lever signal Lv) corresponding to the amount of operation. The lever signals Lv of the control levers 43A, 43B are input to the vehicle body controller 45, which outputs command signals corresponding to the lever signals Lv to the solenoid proportional valves 34a, 34b and the solenoid proportional valves 35a, 35b, thereby controlling the switching direction and stroke amount of the first directional control valve 34 and the second directional control valve 35. At the same time, the pump displacement (discharge flow rate) is controlled by outputting command signals corresponding to the lever signal Lv, the pump discharge pressure sensor 31S, an electric motor rotation speed sensor (not shown), etc. to the regulator 31R of the main pump 31. With this configuration, the control levers 43A, 43B cause each hydraulic actuator to perform the desired operation.

[0018] The first directional control valve 34 is a center bypass type directional control valve, and has a first switching position 34L for rotating the swing motor 13 forward, a neutral position 34N for communicating between the main pump 31 and the hydraulic oil tank 33 and returning the hydraulic oil directly to the hydraulic oil tank 33, and a second switching position 34R for rotating the swing motor 13 reversely. The first directional control valve 34 is configured to be switched to any one of the first switching position 34L, the neutral position 34N, and the second switching position 34R by an internal spool stroking in response to pilot pressures acting on a pair of pressure receiving chambers 34A, 34B, respectively. This controls the flow rate and direction (flow) of the hydraulic oil supplied from the main pump 31 to the swing motor 13.

[0019] The second direction control valve 35 is a center bypass type direction control valve similar to the first direction control valve 34, and has a first switching position 35L that retracts the rod 16C of the arm cylinder 16, a neutral position 35N that connects the main pump 31 and the hydraulic oil tank 33 and returns the hydraulic oil directly to the hydraulic oil tank 33, and a second switching position 35R that extends the rod 16C of the arm cylinder 16. Similar to the first direction control valve 34, the second direction control valve 35 is configured to be switched to any one of the first switching position 35L, the neutral position 35N, and the second switching position 35R by an internal spool stroking in response to pilot pressures acting on a pair of pressure receiving chambers 35A, 35B, respectively. This controls the flow rate and direction (flow) of the hydraulic oil supplied from the main pump 31 to the arm cylinder 16.

[0020] The on-off valve 38 is an electromagnetic proportional valve whose opening is adjusted in proportion to the magnitude of a command current, and the opening area is adjusted in proportion to the magnitude of a command current from the vehicle body controller 45. Therefore, even when the valve is not being operated or when the load on the hydraulic actuator is small, the pressure of the main pump 31 can be freely set. The hydraulic circuit 30 is provided with an oil cooler 81 for cooling the hydraulic oil, which is appropriately cooled by an electric fan (not shown).

[0021] The high-power system 20 includes a fuel cell 21, an inverter 22, an electric motor 23, a secondary battery 25, a boost converter 28, a high-voltage DC-DC converter 29, and a low-voltage DC-DC converter 63, which are electrically connected by a high-power cable. The hydraulic excavator 100 operates by driving the main pump 31 with the electric motor 23. In other words, the electric motor 23 is a power source. In this case, the electric motor 23 is driven using electric power generated by the fuel cell 21, which receives hydrogen from the hydrogen tank 50. In other words, the electric motor 23 is driven by the electric power supplied from the fuel cell 21.

[0022] Since the output of the fuel cell 21 is controlled by voltage, voltage conversion is required between the fuel cell voltage and the system voltage (e.g., 650 V). However, the voltage is boosted by a boost converter 28 provided in the fuel cell 21 to correspond to the rated voltage of the electric motor 23. The inverter 22 converts the DC voltage (system voltage) boosted by the boost converter 28 into an AC voltage, and controls the rotation speed of the electric motor 23. The high-voltage DC-DC converter 29 is a bidirectional voltage converter that steps down the system voltage to charge the secondary battery 25 or steps up the voltage of the secondary battery 25 to the system voltage and supplies it to the inverter 22. The secondary battery 25 can store electricity using surplus power generated by the fuel cell 21, and also functions as a power source that supplies power to loads including the electric motor 23. The secondary battery 25 may be any chargeable and dischargeable power storage device, and may be formed, for example, from a lithium ion battery or a nickel-metal hydride battery. The secondary battery 25 is provided with a battery sensor (not shown) for detecting the operating state of the secondary battery 25, such as its voltage, current, and remaining capacity (SOC (State Of Charge)).

[0023] The vehicle body controller 45 is a higher-level controller that controls the entire system of the hydraulic excavator 100, and outputs appropriate command values ​​to the electromagnetic proportional valves 34a, 34b, 35a, 35b of the hydraulic circuit 30, lower-level controllers (fuel cell controller 47, battery controller 46), low-voltage DCDC converter 63, inverter 22, etc. These controllers are connected to a low-voltage circuit 60 (e.g., 24 V) including a lead battery 61. A low-voltage DC-DC converter 63 is connected to the low-voltage circuit 60, and generates a stable low voltage using power from the high-power system 20. The lead battery 61 is connected to the low-voltage circuit 60 via a disconnect switch 62, and the disconnect switch 62 is configured to be able to cut off the system power supply source for the purposes of preventing the lead battery from wearing out, preventing theft, improving safety during vehicle maintenance, etc. Furthermore, a key switch 64 is connected to the vehicle controller 45 and controls the start and stop of vehicle operations.

[0024] The hydrogen tank 50 stores hydrogen to be used in the fuel cell 21. The hydrogen tank 50 is a pressure-resistant container made of, for example, metal or resin. The hydrogen tank 50 may also include a compressor that adjusts the hydrogen to an appropriate pressure, a precooler that cools the hydrogen, a hydrogen valve that adjusts the flow rate of the hydrogen, and the like. The hydrogen tank 50 is provided with a hydrogen fill port 55 that fills the hydrogen tank 50 with hydrogen.

[0025] Fig. 3 is a left rear view of the revolving body 4 of the hydraulic excavator 100 of this embodiment. Fig. 4 is a right front view of the revolving body 4 of the hydraulic excavator 100 of this embodiment. 5A is a diagram showing a cross-sectional view of the revolving unit 4. FIG. 5B is a diagram in which the position of the cross-section of FIG. 5A has been changed to clarify the position of the heavy-power system 20. FIGS. 5A and 5B are diagrams viewed from the V direction of FIG. 4. FIG. 6A is a diagram showing a top view of the revolving unit 4. FIG. 6B is a diagram in which the position of the cross-section of FIG. 6A has been changed to clarify the position of the heavy-power system 20. FIGS. 6A and 6B are diagrams viewed from the VI direction of FIG. 4. In order to facilitate the explanation of the hydraulic excavator 100 of this embodiment, the exterior cover 90 has been removed to allow the components to be seen.

[0026] 3 and 4, exterior cover 90 includes a hydrogen tank-side exterior cover 90A that covers high-power system 20, which includes fuel cell 21 and electric motor 23, and hydrogen tank 50. Hydrogen tank-side exterior cover 90A has an opening 92 at a position corresponding to the top of hydrogen tank 50. Hydrogen tank-side exterior cover 90A also has a hydrogen fill port 55 for filling hydrogen into hydrogen tank 50.

[0027] As shown in Figures 5A and 6A, the hydrogen tank 50 is installed at the rear of the rotating bed 4 and in front of the counterweight 10. As shown in Figures 5B and 6A, the hydrogen tank 50 is located above the high-power system 20, which includes the fuel cell 21 and the electric motor 23, and overlaps with the high-power system 20 in a top view. This configuration allows the hydrogen piping (not shown) to be shortened. The counterweight 10 can also protect the hydrogen tank 50 from impacts from behind. Furthermore, since the rear end radius can be kept approximately the same as before, the risk of contact with obstacles at the rear can be reduced. 5A, hydrogen tank 50 is disposed facing opening 92. As a result, even if hydrogen leaks from hydrogen tank 50, the hydrogen, which has a lower density than air, moves upward and is quickly discharged through opening 92. The hydrogen tank 50 and the fuel cell 21 are connected by a hydrogen pipe (not shown), so that hydrogen can be supplied to the fuel cell 21. 5A and 5B, the high-power system 20, which includes the fuel cell 21 and the electric motor 23, is separated from the hydrogen tank 50 by a partition member 95. The partition member 95 is box-shaped with an opening at the top. A hydrogen tank-side exterior cover 90A is placed in the opening at the top of the partition member 95. As a result, the hydrogen tank-side exterior cover 90A, which is part of the exterior cover 90, and the partition member 95 together define a hydrogen tank storage chamber that houses the hydrogen tank 50. The hydrogen tanks 50 are installed at approximately the same height near the bottom of the opening 92. In this case, it can also be said that multiple hydrogen tanks 50 are installed side by side at the same height. This makes it possible to reduce the overall height of the hydraulic excavator 100, and because the hydrogen tanks are not located far from the opening, they can be quickly discharged to the outside in the event of a leak. As shown in FIGS. 3, 4 and 5B, a hydrogen tank side exterior cover 90A that defines the hydrogen tank storage chamber is provided with a hydrogen fill port 55 for filling the hydrogen tank 50 with hydrogen.

[0028] Returning to FIG. 2, the system operation of this embodiment will be described. When the driver turns on the key switch 64 in the driver's cab 8, the vehicle body controller 45 is started. The vehicle body controller 45 starts up the inverter 22, the low-voltage DCDC converter 63, the battery controller 46, and the fuel cell controller 47, and the battery controller 46 then starts up the secondary battery 25 and the high-voltage DCDC converter 29. In addition, the fuel cell controller 47 starts up the fuel cell 21, the boost converter 28, and a hydrogen valve (not shown) connected to the hydrogen tank 50.

[0029] The vehicle controller 45 controls the power generation of the fuel cell 21, the driving of the electric motor 23, the hydraulic circuit 30, etc., according to the settings of the work mode selection switch 41 and the motor control dial 42, and the lever signal Lv of the operation levers 43A and 43B.

[0030] On the other hand, when the driver turns off the key switch 64 in the driver's cab 8, the vehicle body controller 45 stops the inverter 22, thereby stopping the electric motor 23. At the same time, the fuel cell controller 47 stops the fuel cell 21, the boost converter 28, and a hydrogen valve (not shown) connected to the hydrogen tank 50, thereby stopping power generation. After the fuel cell controller 47 has completed the stop process (after power generation has stopped), it stops the low-voltage DC-DC converter 63 and the battery controller 46. In this way, surplus power in the high-power system 20 during the stop process is charged into the lead battery 61 and the secondary battery 25.

[0031] FIG. 7 is a diagram illustrating a method for filling the hydraulic excavator 100 with hydrogen. Hydrogen gas can be filled by connecting a hydrogen filling nozzle 205 of a hydrogen supply facility such as a mobile hydrogen station 200 to the hydrogen filling port 55. When the hydrogen filling nozzle 205 is connected to the hydrogen filling port 55, the hydrogen station 200 and the hydrogen tank control unit 475 of the fuel cell controller 47 begin to communicate with each other, and the hydrogen station 200 controls the hydrogen supply according to the temperature and pressure of the hydrogen tank 50.

[0032] Generally, a hydrogen leak detection sensor 51 is provided near the hydrogen tank 50, and when a hydrogen leak is detected, the hydrogen tank control unit 475 performs control to close the hydrogen valve of the hydrogen tank 50. When hydrogen is being filled, the supply of hydrogen is also stopped at the hydrogen station 200.

[0033] However, when detecting a hydrogen leak, sufficient detection may not be possible depending on the installation position of the hydrogen leak detection sensor 51. Furthermore, if the hydrogen leak detection sensor 51 malfunctions, it may not be possible to detect a hydrogen leak. Hydrogen can explode if it reacts with a fire or static electricity, but the risk of ignition is small when the hydrogen concentration is low. Therefore, in order to prevent hydrogen ignition, it is important to prevent hydrogen from accumulating and to isolate hydrogen from areas where electricity is present.

[0034] 5A and 5B, in the hydraulic excavator of this embodiment, a partition member 95 is provided between the high-power system 20 and the hydrogen tank 50. As a result, in this embodiment, even if hydrogen leaks from the hydrogen tank 50, the hydrogen leaked to the hydrogen tank 50 side can be isolated from the electricity on the high-power system 20 side. 5A, the hydraulic excavator of this embodiment has an opening 92 at the top of the exterior cover 90 that covers the hydrogen tanks 50. Each hydrogen tank 50 is also located near the bottom of the opening 92. With this structure, even if hydrogen leaks from the hydrogen tank 50, the hydrogen, which is lighter than air, is quickly released outside the vehicle body.

[0035] 5B, the hydrogen tank 50 is provided above the high-power system 20. This makes it difficult for hydrogen to flow toward the high-power system 20, and even if it does flow, the amount is small. Furthermore, in the hydraulic excavator 100 of this embodiment, as shown in Figure 5B, the hydrogen fill port 55 is provided on the hydrogen tank side exterior cover 90A. As a result, the hydrogen fill port 55 is provided on the hydrogen tank 50 side of the partition member 95, and the high-power system 20 is provided on the opposite side of the partition member 95 from the hydrogen tank 50 side. As a result, the storage path and the high-power system 20 can be isolated from each other even during hydrogen filling.

[0036] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention. [Explanation of symbols]

[0037] 20...High-power system, 21...Fuel cell, 23...Electric motor, 30...Hydraulic circuit, 40...Operating system, 50...Hydrogen tank, 55...Hydrogen filling port, 90...Exterior cover, 90A...Hydrogen tank side exterior cover, 92...Opening, 95...Partition member, 100...Hydraulic excavator

Claims

1. a fuel cell; and an electric motor driven by power supplied from the fuel cell; a hydrogen tank for storing hydrogen to be supplied to the fuel cell; an exterior cover that covers the fuel cell, the electric motor, and the hydrogen tank; In an electric work machine equipped with the fuel cell and the electric motor are separated from the hydrogen tank by a partition member within the exterior cover, The electric working machine is characterized in that the exterior cover has an opening at a position corresponding to the top of the hydrogen tank.

2. The electric working machine according to claim 1 , wherein the hydrogen tank is provided facing the opening.

3. The electric work machine according to claim 2, wherein the hydrogen tank is provided above the fuel cell and the electric motor.

4. The electric working machine according to claim 3 , wherein the hydrogen tank is provided at a position overlapping the fuel cell and the electric motor in a top view.

5. 3. The electric working machine according to claim 2, wherein a plurality of the hydrogen tanks are arranged at the same height.

6. a portion of the exterior cover, together with the partition member, defines a hydrogen tank housing chamber that houses the hydrogen tank; 2. The electric working machine according to claim 1, wherein a hydrogen fill port for filling the hydrogen tank with hydrogen is provided in a part of the exterior cover that defines the hydrogen tank housing chamber.

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