Electric work vehicles

Abstract

While the development of environmentally friendly electric work equipment is desirable, conventional batteries using electrolyte require high-capacity batteries for high output or long-duration operation. However, space and weight constraints have prevented the installation of batteries of sufficient capacity in work vehicles. [Solution] While utilizing fuel cells as a power source, the hydrogen tanks are separated into the front axle section and the driver's seat section, resulting in a more compact design that can also be shared with the power specifications of internal combustion engines.

Description

Technical Field

[0001] The present invention relates to a work vehicle powered by a fuel cell.

Background Art

[0002] Although the development of electric work machines considering the environment is desired, in the case of conventional batteries using electrolytic solutions, when performing a large output or long-time work, a large-capacity battery is required, and due to space and weight relationships, a battery with a sufficient margin cannot be mounted in the size of the work vehicle.

[0003] Also, when using an internal combustion engine as power, although it is possible to miniaturize the fuel tank because liquid fuel is used, there is a problem that it cannot be an environmentally friendly power source due to carbon dioxide generation. (Patent Document 1)

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the prior art, there is a technique that uses a fuel cell with a gas tank provided under a cabin that houses a driver's seat to achieve weight balance.

[0006] However, in order to arrange a plurality of gas tanks side by side above the upper part of the rear wheel axle, the cabin including the operation seat is configured to rise upward.

[0007] An object of the present invention is to provide a work vehicle that eliminates the sense of discomfort in operation by arranging gas tanks at two locations, the lower part of the cabin and the upper part of the front axle, with different heights, so that the height from the ground and the front-rear positional relationship of the operation seat are the same as those of an engine vehicle or an electric vehicle using a liquid battery. [Means for solving the problem]

[0008] The first invention is solved by the following technical means.

[0009] The hydrogen tank 50 is positioned above the front axle 20 connecting the left front wheel 21 and the right front wheel 25, parallel to the direction of travel, with the upper rear end 51 of the hydrogen tank 50 located forward of the foot position 41 of the operator's seat unit 40 and above the bottom surface position 42 of the footwell.

[0010] The second invention is solved by the following technical means.

[0011] The hydrogen tank 60 is positioned rearward from the foot position 41 of the operator's seat unit 40 in the direction of travel, and below the bottom surface position 42 of the foot area.

[0012] The third invention is solved by the following technical means.

[0013] A power rotation transmission mechanism case 30 is positioned between the left rear wheel 31, the right rear wheel 35, and the external power output shaft 38. It is connected to the hydrogen tank case 61 that secures the hydrogen tank 60 and the hydrogen tank frames 52 and 52A that secure the hydrogen tank 50. It is positioned perpendicular to the rear wheel axle position 39 that connects the left rear wheel axle 32 and the right rear wheel axle 36, forming the vehicle body frame unit 70. The battery 80 and fuel cell unit 90 are positioned on the upper side of the vehicle body frame unit 70, towards the front in the direction of travel.

[0014] The fourth invention is solved by the following technical means.

[0015] The fuel cell unit 90 has an electrolyte 91 in the center and is configured in layers through which cooling water, hydrogen, and air flow. The cooling water layer 92 is oriented parallel to the direction of travel. The cooling radiator 111 and battery 80 of the hydraulic unit 110 for lifting and lowering the work equipment, and the cooling water radiator device 120 are positioned in front of the fuel cell unit 90 in the direction of travel. The airflow from the cooling water radiator device 120 is exhausted from the ventilation opening 132 in front of the hood 130. The cooling water from the cooling water radiator device 120 passes through the cooling water radiator 121, the cooling pipe layer 81 of the battery 80, and the cooling water layer 92 of the fuel cell unit 90, flows over the top of the hydrogen tank 50, and circulates back to the cooling water radiator device 120.

[0016] The fifth invention is solved by the following technical means.

[0017] A drain port 95 for water discharged from the fuel cell unit 90 is provided between the frame unit 70 and the hood 130, allowing the water to be discharged downwards from the work vehicle. [Effects of the Invention]

[0018] Based on the first and second inventions, it is possible to position the hydrogen tank, fuel cell, and battery at the front of the work vehicle while ensuring sufficient legroom in the operator's seat, and to position the operator's seat at the same height and fore-aft position as an engine-powered vehicle. This allows operators to switch between fuel cell vehicles and engine or liquid battery vehicles without any discomfort from the operator's seat. At the same time, weight balance is maintained, and the balance is not disrupted when raising or lowering the work equipment.

[0019] The third invention allows for increased rigidity of the work vehicle. While engine-equipped vehicles maintain vehicle rigidity through the transmission case, this invention makes it possible to maintain vehicle strength by utilizing the rigidity of the hydrogen tank itself.

[0020] From the fourth invention, It is possible to prevent the fuel cell from overheating.

[0021] From the fifth invention, the water discharged from the fuel cell can be sprinkled on the field in a natural form. It is possible to prevent the generation of water accumulation and moisture inside the work vehicle.

Brief Description of the Drawings

[0022] [Figure 1] Left side view of the work vehicle of the present invention [Figure 2] Left side cross-sectional view at the wheel position with the hood of the work vehicle of the present invention removed [Figure 3] View of the running part of the work vehicle of the present invention as seen from the lower left [Figure 4] Overall layout diagram of the fuel cell, battery, and hydrogen tank of the work vehicle of the present invention [Figure 5] Layout diagram of the hydraulic unit of the work vehicle of the present invention [Figure 6] Cross-sectional view of the center of the vehicle showing the positional relationship between the fuel cell, battery, hydrogen tank, piping, hood, and operator's seat unit of the work vehicle of the present invention [Figure 7] Layout relationship diagram in the case of the engine specification of the present invention [Figure 8] Diagram showing the positional relationship between the front axle of the work vehicle of the present invention, the drive motor for the front wheels, and the drain port of the water of the fuel cell [Figure 9] Diagram showing the flow of the cooling water and the layout relationship between the fuel cell and the battery of the present invention [Figure 10] Block diagram showing the relationship between the components of the present invention [Figure 11] Block diagram 2 showing the relationship between the components of the present invention

Modes for Carrying Out the Invention

[0023] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0024] The work vehicle shown in FIGS. 1 to 10 shows an example of the present embodiment.

[0025] In agricultural and construction machinery, work vehicles that utilize high-powered engines for extended periods emit large amounts of carbon dioxide, which is not an environmentally desirable specification.

[0026] This invention proposes a work vehicle that utilizes a hydrogen fuel cell, and by arranging the vehicle's configuration in a similar way to that of an internal combustion engine, it aims to avoid any unfamiliarity with the operator's feel. Furthermore, by sharing interchangeable exterior parts and other components, it is possible to utilize the same specifications as an internal combustion engine, thereby improving productivity. In particular, even if unmanned operation is possible, human operation is required when driving on public roads and during initial teaching operations, so ease of operation is essential, and a configuration that does not compromise the operator's seat is desirable.

[0027] This document describes the configuration of a work vehicle powered by the fuel cell of the present invention. Although this embodiment is described using a tractor, the basic configuration is also applicable to riding cultivators, rice transplanters, lawnmowers, and four-wheeled construction machinery.

[0028] Furthermore, the hydrogen tank is a gas tank specification, and although it is referred to as a hydrogen tank in this invention, it is not limited by the type of gas it contains, but rather refers to any tank that holds gas.

[0029] In this invention, the directions are described in the left, right, up, and down directions, as viewed from the perspective of a person seated in the operating seat unit 40 of a work vehicle, with respect to the direction of travel.

[0030] Figure 1 is a left side view of the work vehicle. The work vehicle 10 is capable of both unmanned and manned operation, and is equipped with an operator's seat unit 40, allowing a person to sit in the operator's seat and operate the vehicle.

[0031] During unmanned operation, the satellite positioning device 11 can detect its own position based on artificial satellites and ground reference positions. The satellite positioning device is also equipped with an inertial measuring instrument, which is used to obtain information on the acceleration state, tilt state, and position during slippage and turning of the work vehicle. Below the satellite positioning device 11, a LiDAR 12, a positioning device that utilizes radar technology, is installed to detect obstacles and the state of the travel path while driving. Note that the LiDAR 12 may also be an AI camera, as long as it can detect the shape of an object, the distance to the object, and its movement.

[0032] In this embodiment, the satellite positioning device 11 and LiDAR 12 are positioned on the front side above the operator's seat unit 40 to prioritize detection accuracy in the forward direction while making it easy to detect the entire work vehicle 10.

[0033] Furthermore, since operation is primarily controlled remotely, the vehicle is equipped with a system that uses imaging devices to check the driving status and allow for real-time monitoring of the operating status from a remote location. A forward imaging device 14 is positioned near the lighting device 15 at the front of the work vehicle, while rear imaging devices 13L and 13R are positioned for rearward monitoring.

[0034] The power configuration of the work vehicle 10 has the advantage of being partially shared between a configuration using an engine, a configuration utilizing electricity stored in a liquid battery, and a configuration utilizing a fuel cell as described in this invention. This is because, when operating a work vehicle, workers often intuitively remember the field of view from the operator's seat, the distance between their hands and feet, the dimensions of the vehicle, and its position relative to the outside. By keeping the main shape and positional relationship of the work vehicle similar even if the power configuration differs, it is possible to provide a work vehicle configuration that is easy for a variety of workers to use in large-scale agricultural facilities.

[0035] Figure 1 is a left side view with the covers attached, and Figure 2 is a cross-sectional view of the same left side view with the hood 130 and hydrogen tank case 61 removed. Inside the front of the hood 130, a cooling water radiator device 120 is installed, which discharges outside air from the front of the hood 130 and draws it into the hydraulic radiator 111, battery 80, and fuel cell 90 located at the rear, thereby preventing heat buildup and performing cooling.

[0036] Fuel cells generate electricity through chemical reactions, but the hydrogen gas that is the source of electricity generation is separated and placed in hydrogen tank 50 and hydrogen tank 60. In order to obtain sufficient electromotive force and power for a long period of time, the hydrogen tank capacity must be sufficient. In vehicles that require traction, such as tractors, the rear wheels in the direction of travel are large-diameter wheels, and the front wheels used for steering are small-diameter wheels. Therefore, the front axle position 28 is at a lower ground clearance than the rear axle position 39. As mentioned above, in order to obtain the hydrogen tank capacity, in configurations with limited vehicle width, a tank shape that is long in the front-to-rear direction of the vehicle is desirable. At the same time, it is necessary to secure space for the operator's seat unit 40, but if a hydrogen tank that is long in the front-to-rear direction is installed, the operator's seat unit 40 will be mounted on top of the hydrogen tank.

[0037] In this invention, to solve this problem, the hydrogen tank is divided into two, and the vertical positions of the hydrogen tank 50 located at the front and the hydrogen tank 60 located at the rear are offset. This difference in space makes it possible to secure a foot position 41 and a foot base position 42 that allow a person to extend their feet and operate the accelerator and brake pedals when seated in the operating unit 40. The hydrogen tanks 50 and 60 are cylindrical high-pressure vessels made of hard synthetic resin reinforced with carbon fiber or glass fiber, and the hydrogen tanks themselves have a certain degree of rigidity and can withstand some stress.

[0038] By dividing the hydrogen tank at the upper rear end 51 of the hydrogen tank 50 and at the foot position 41, the division point is designed to absorb twisting and bending in the longitudinal direction of the work vehicle. If it were a single hydrogen tank, the hydrogen tank itself could be damaged by the stress applied to the tractor.

[0039] Even replacing a hydrogen tank is not easy, as it involves the task of removing a single, long unit. As shown in Figure 3, the hydrogen tank 50 can be removed from the hydrogen tank frames 52 and 52A without having to mount the front wheels.

[0040] In an engine-powered tractor, the rear of the hydrogen tank frames 52 and 52A are connected to the transmission case for the tractor's gear shift, forming the basic frame of the tractor. In this invention, the hydrogen tank case 61 and the power rotation transmission mechanism case 30 are connected and then connected to the hydrogen tank frames 52 and 52A to form the vehicle body frame unit 70. The vehicle body frame unit 70 has sufficient rigidity for a work vehicle. The bottom of the hydrogen tank case 61 is open, and the hydrogen tank 60 can be attached and detached through this open opening. Therefore, the vehicle body frame unit 70 forms the basic frame of the work vehicle and can withstand sufficient strength for work driving.

[0041] The power rotation speed change mechanism case 30 houses a PTO electric motor 39, and the rotation speed is changed by the speed change mechanism built into the transmission case or by an inverter function, enabling output to the PTO shaft 38.

[0042] On the left side of the power rotation transmission mechanism case 30, the left rear wheel electric motor 33 is connected and outputs to the left rear wheel axle 32. On the right side, the right rear wheel electric motor 37 is connected and outputs to the right rear wheel axle 36. Each output shaft is connected to a rear wheel, and the power path at the rear of the vehicle body frame unit 70, which is in contact with the ground, is formed.

[0043] The front axle 20 is connected to the hydrogen tank frames 52 and 52A at the front of the vehicle's frame unit 70. The front axle case is connected to the front wheel motor 29, and the case contains a power transmission mechanism that outputs power to the front left wheel axle 22 and the front right wheel axle 26.

[0044] The front axle is compatible with left and right steering and vertical movement of the left and right wheels. As mentioned above, the front axle position 28 is lower than the rear axle position 39. Therefore, mounting the hydrogen tank below the front axle 20 would require raising the overall ground clearance, which is an unreasonable configuration. To improve this, it is desirable to position the hydrogen tank 50 at the hydrogen tank frame 52, 52A shown in the diagram, and to position it above the hydrogen tank 60 located at the rear of the vehicle body frame unit 70.

[0045] In the first invention, the hydrogen tank 50 is positioned above the front axle 20 connecting the left front wheel 21 and the right front wheel 25, parallel to the direction of travel, and the upper rear end 51 of the hydrogen tank 50 is located forward of the foot position 41 of the operator's seat unit 40 in the direction of travel, and above the bottom surface position 42 of the footrest.

[0046] In the second invention, the hydrogen tank 60 is positioned rearward from the foot position 41 of the operator's seat unit 40 in the direction of travel, and below the bottom surface position 42 of the footrest. This makes it possible to keep the position of the operator's seat unit 40 the same as the engine specification and liquid battery specification, as well as the same vertical position, front-to-back position, and volume of the operator's seat unit 40. The hydrogen tank case 61 and the hydrogen tank frames 52 and 52A are joined by welding. As they are made of steel plates, some distortion in the left-to-right direction is tolerable, but distortion in the vertical direction is minimal. Therefore, the clearance with the hydrogen tank in the vertical direction is narrowed, making it possible to arrange multiple hydrogen tanks side by side.

[0047] Furthermore, the open bottom of the hydrogen tank case 61 allows for stress release from the left and right sides of the hydrogen tank case 61 and also allows for heat release when the hydrogen tank 60 generates heat. Although a large hole is shown in the diagram, it would also be better to use a removable lid with some small holes, like a mesh.

[0048] In other words, if hydrogen tanks are stacked vertically, heat will be transferred upwards, causing the temperature of the upper hydrogen tanks to rise. To address this heat flow, if the clearance is increased not only vertically but also longitudinally along the entire length of the hydrogen tanks, the airflow will be directed forward and backward, and heat will be expelled from the rear downwards, reducing heat buildup.

[0049] In this embodiment, a single hydrogen tank is shown, but it is also possible to arrange multiple tanks horizontally side by side. In the case of the single hydrogen tank case 61 and hydrogen tank 60 combination in this embodiment, the clearance on the left and right sides in the horizontal direction is widened to address heat buildup and stress on the work vehicle 10.

[0050] As described above, hydrogen tanks 50 and 60 are cylindrical high-pressure vessels made of rigid synthetic resin reinforced with carbon fiber or glass fiber. The hydrogen tanks themselves have a certain degree of rigidity and can withstand some stress. However, the hydrogen tanks do not bear the stress applied to the work vehicle. The stress is distributed and received by utilizing the entire frame unit 70, so that no external force acts on the hydrogen tanks.

[0051] The horizontal clearance between the hydrogen tank frames 52 and 52A that support the hydrogen tank 50, and the horizontal clearance between the hydrogen tank frame 61 that supports the hydrogen tank 60, are wider than the vertical clearance. This clearance is used to create an airflow channel that allows air to escape from the hydrogen tanks.

[0052] The work vehicle 10 is long in the direction of travel and is equipped with hydrogen tanks along its length. By widening the clearance in the length and vertical directions, an airflow path is created between the hydrogen tanks. At the same time, when stress is generated on the vehicle, the hydrogen tanks do not interfere with each other, and the clearance of the airflow path is not narrowed. In addition, the operator's seat unit 40 has rigidity in three directions: left, right, front, rear, up, and down. By positioning the hydrogen tank 60 below the operator's seat unit in the front-rear direction, it has a strain that is linked to the operator's seat unit 40, and stress can be relieved at the interface 131 between the operator's seat unit 40 and the hood 130. In this structure, the joint between the hydrogen tank case 61 and the hydrogen tank frames 52 and 52A is also a welded joint. This joint coincides with the interface 131 and is also the boundary between the hydrogen tank 50 and the hydrogen tank 60. Furthermore, the hydrogen tank 50 and the hydrogen tank 60 have a structure where they are at different levels in the vertical direction, so stress on the hydrogen tank can be prevented at the interface 131.

[0053] This structure allows for the absence of the rigidity of the transmission case found in conventional engine configurations, and the frame unit 70, which is composed of the hydrogen tank case 61 and the hydrogen tank frames 52 and 52A, to handle this without requiring such rigidity.

[0054] The electric motor mechanism is explained in Figures 4, 5, and 10.

[0055] This is a fuel cell 90 equipped with an FC stack and a control unit that manages the state of the FC stack. It is a system that generates electricity using hydrogen gas in hydrogen tanks 50 and 60 and supplies power to each electric motor, making it a fuel cell-powered electric vehicle.

[0056] <Fuel cell> In the embodiment shown in Figure 4, there is a layer of electrolyte 91 in the center of the cased interior of the fuel cell 90. The fuel electrode 93, located outside of the electrolyte, is filled with hydrogen gas supplied from the hydrogen tank 50. Hydrogen gas exists as hydrogen molecules, with protons and electrons bonded together. However, for these hydrogen molecules to pass through the electrolyte layer 91, the protons and electrons are separated, leaving only the electrons at the fuel electrode, while the protons move to the air electrode 94. The air electrode 94 is opposite the fuel electrode 93, separated by the electrolyte layer 91. Oxygen from the atmosphere is taken in by the air electrode 94 through the intake port 96, and the protons that have passed through the electrolyte 91 are taken in, converted into water within the air electrode 94, and discharged as water through the drain port 95.

[0057] The fuel electrode 93 and the air electrode 94 are connected by a power line, and the electrons separated by the fuel electrode 93 flow into the power line, making it possible to extract electricity.

[0058] In this embodiment, the electrolyte 91, fuel electrode 93, and air electrode 94 are represented in a simplified diagram with large divisions. However, to further increase efficiency, these layers can be made into thin layers, and a cooling water layer 92 can be inserted between them to reduce the heat generated between the layers.

[0059] Furthermore, although not shown in the diagram, there is a catalyst layer and a gas diffusion layer between the electrolyte layer 91 and the fuel electrode 93, which enhance the effect of separating protons and electrons from hydrogen. These configurations achieve similar effects even when the layers are thin.

[0060] Thus, it is also possible to adopt a structure in which the electrolyte 91, fuel electrode 93, and air electrode 94 are stacked in multiple thin layers, with cooling water or cooling air layers placed between them, thereby enhancing the cooling effect of the heat generated by the chemical reaction between the electrolyte 91 and the fuel electrode 93. In this case, each layer is in the form of a sheet or thin film.

[0061] Technically, the aforementioned fuel electrode 93 and air electrode 94 are connected by fine wires, and the connected electrodes are linked together to form a power transmission line that can supply electricity, consolidating the electrical energy and charging the battery 80.

[0062] Similarly, in the case of a thin film, the supply of hydrogen gas to the fuel electrode 93 and the supply of oxygen to the air electrode 94 are carried out separately for each layer, requiring a supply pressure. In particular, some configurations utilize a compressor for supplying oxygen from the atmosphere.

[0063] The hydrogen gas is supplied into separator 97, while oxygen from the atmosphere is taken in through separator 98.

[0064] In this way, fuel cells generate heat and water through chemical reactions between electrodes, but they do not produce carbon dioxide like internal combustion engines.

[0065] Figure 7 is a diagram of the powertrain layout in the case of an engine specification. The fuel cell 90 is located in the position corresponding to the engine 150, but in the engine, the engine is located from the position corresponding to the hydrogen tank frames 52 and 52A downwards. Even if the area occupied by the fuel cell 90 is lowered to the lower end position 153 of the engine 150, and its position in the front-to-back direction is shortened, the hydrogen tanks 50 and 60 will be separated by a long distance in the area occupied by the fuel cell, resulting in a long pipe that bends in several places. In this case, the pressure in the pipe will be attenuated by pipe resistance, making it impossible to measure the pressure accurately, and it will also become impossible to control the pressure in the hydrogen tanks 50 and 60 within a certain range. When valves 58 and 62 are opened, pressure may be generated that causes hydrogen gas to flow in the reverse direction. Therefore, the hydrogen tanks 50 and 60 should be connected by a short pipe as shown in Figure 2 or Figure 6. Furthermore, as explained above, this problem can be solved by positioning the upper rear end 51 of the hydrogen tank 50 in a manner that relieves the stress on the work vehicle 10, so that it is located forward of the foot position 41 of the operator's seat unit 40 in the direction of travel, and above the bottom surface position 42 of the footrest.

[0066] In the 150 engine specification, the air cleaner is located at 151, the radiator at 152, and the battery is positioned at the front in the direction of travel.

[0067] <Battery> Battery 80 is a lithium-ion battery designed for high voltage applications, and its charging and discharging are managed by a Battery Management System (BMS) 81, which controls and manages the battery. It also works in conjunction with a DC / DC converter 83 to supply high or low voltage.

[0068] In this embodiment, the power supply for the VCU (Battery Control Unit) 82, BMS 81, and DC / DC converter 83 is directly from the high-voltage power supply of the battery 80. However, there is also a configuration in which a low-voltage battery section is connected to the battery 80 and used as the power supply for the VCU 82, BMS 81, and DC / DC converter 83, serving as an auxiliary battery for the equipment.

[0069] Alternatively, if a low-voltage battery such as a lead-acid battery is provided separately, the BMS may manage the charging from the high-voltage battery, and it may be used as an auxiliary battery for low-voltage equipment.

[0070] Both serve the function of secondary batteries, temporarily storing the power generated by the fuel cell 90.

[0071] <Lifting circuit> A voltage adjustment device is required between the fuel cell 90 and the battery 80. Figure 10 shows a boost circuit 84. By adjusting the voltage to match the voltage capacity of a single battery, the battery is charged in accordance with the voltage differences used between different models. Although the battery 80 is shown as a single unit in the figure, a boost or buck circuit is combined to adjust the voltage depending on the voltage difference and how the battery is connected. Alternatively, a boost or buck circuit may be placed between the battery and each motor for adjustment.

[0072] <mcu> In this invention, the inverter that adjusts the voltage from the battery and controls the rotational speed is located within the MCU (motor control unit) of each motor, and is configured to also adjust the voltage. When converting DC current to AC current and controlling the rotational speed, the motor is equipped with a capacitor that stores starting power, allowing for instantaneous rotation in the intended direction.

[0073] <vcu> The overall control of the vehicle is performed by the VCU82 (Battery Control Unit), which controls the BMS81 and DC / DC converter 83 in conjunction. Although not described in detail for simplicity, the MCUs (Motor Control Units) of each motor are also controlled by CAN communication from the VCU as higher-level instruction signals.

[0074] <DC / DC コンバータ> The DC / DC converter 83 significantly changes the voltage, ensuring the appropriate voltage for each drive motor, and acts as a relay through control. Although details are not described, it is a unit that also supplies power to the motor for the cooling water radiator 121, the small air conditioning fan, and various control motors and electric cylinders, and manages the voltage of each component.

[0075] <Cooling System Hood> The fuel cell unit 90, battery 80, and cooling radiator 111 of the present invention are configured to be cooled by water cooling. Since the work vehicle does not travel at the same speed as an automobile, cooling using air is not sufficiently effective. In the direction of travel of the work vehicle 10, a cooling water radiator device 120 is installed at the very front inside the hood 130, and a cooling water radiator 121 is positioned at the rear, and the cooling water flowing inside is cooled by the air flowing outside. The heated air is exhausted through a ventilation opening 132 located at the front of the hood 130.

[0076] The radiator fen of the cooling water radiator device 120 is drawn in from below the hood 130, passing through the side of the hydrogen tank 50 located below the hood 130. This results in air cooling, but also provides a cooling effect for the hydrogen tank 50. Similarly, the inside of the hood 130 is also ventilated, preventing heat buildup inside the hood 130.

[0077] The hydraulic system cooling radiator 111 is cooled by the suction air from the radiator fen of the coolant radiator device 120.

[0078] In Figure 9, the coolant cooled by the coolant radiator 121 flows through pipe 122A into the battery cooling case 85. This coolant cools the battery 80 and fuel cell 90, and then returns to the coolant radiator 121 through pipes 122F and 122G.

[0079] <Cooling System Battery> The battery 80 generates heat during charging and discharging, and therefore needs to be cooled. Cooling is performed by passing cooling water through a battery cooling case 85 that contacts the sides and bottom of the battery 80 and supports the bottom of the battery 80, and placing the battery 80 inside this case. The cooling water flowing into the battery cooling case 85 is the cooling water supplied from the cooling water radiator device 120 through piping 122A.

[0080] The cooling water that has cooled the battery 80 in the battery cooling case 85 cools the fuel cell 90 through the piping 122B.

[0081] <Cooling System Fuel Cell> Figure 6 shows the position of the hood 130 and the steering positions of the cooling water radiator system 120, the hydraulic system cooling radiator 111, the battery 80, the fuel cell 90, the hydrogen tank 50, the hydrogen tank 60, and the control unit 40.

[0082] Fuel cells have the challenge of being large in volume and generating heat, so they must be configured to allow for sufficient cooling.

[0083] In the section describing the fuel cell mentioned above, the flow of cooling water into the cooling water layer 92 located between the electrolyte layer 91 and the fuel electrode layer 93 was explained. The cooling water that flows into the aforementioned battery cooling case 85 then flows further into the cooling water layer 92. The battery 80 also generates heat, but not to the same extent as the fuel cell. Therefore, the cooling water used to cool the battery 80 and perform heat exchange is then used to cool the fuel cell.

[0084] Heat exchange takes place within the fuel cell, and the cooling water, now containing heat, passes over the top of the hydrogen tank 50. The sides of the hydrogen tank 50 are cooled by the suction air from the cooling water radiator device 120, but the top tends to retain heat. Although only the piping for the cooling water after heat exchange passes through this area, it can be used to alleviate heat buildup.

[0085] Figure 9 illustrates the general flow of cooling water within the fuel cell 90. As mentioned earlier, fuel cells consist of multiple thin layers to improve efficiency, but in the figure, they are represented as a large mass.

[0086] The cooling water flows into the fuel cell 90 through the exhaust pipe 122B and enters the piping 122C of the cooling water layer 92 on the fuel electrode 93 side. Because this cooling water layer 92 is parallel to the direction of flow, it is easy for the water to flow over long distances and does not create resistance. If an air layer is provided in between, it is possible to use both water cooling and air cooling, which is also an advantage of the fourth invention. The cooling water circulates efficiently and flows through piping 122D to the piping 122E of the cooling layer on the air electrode 94 side. After this circulation and sufficient heat exchange, the cooling water returns to the cooling water radiator 121 through piping 122F and piping 122G.

[0087] As can be seen in the view from below in Figure 3, the bottom of the fuel cell 90 is open to the field, allowing dust that enters the fuel cell to fall down. Additionally, the cooling water layer 92 is located above the hydrogen tank 50 below it, which inevitably draws up heat from the top of the hydrogen tank 50. As in the fourth invention, the water flows over the top of the hydrogen tank 50 and circulates to the cooling water radiator device 120.

[0088] Alternatively, the cooling water piping from the fuel cell may be routed around the hydrogen tank.

[0089] <Radiator for cooling hydraulic systems> The hydraulic system cooling radiator 111 is also used for raising and lowering the work equipment of the work vehicle and for power output, and is connected to the hydraulic cylinder and hydraulic system motor.

[0090] In Figures 4 and 5, the hydraulic unit 110 is located above the power rotation transmission mechanism case 30 and below the operating unit 40, and its positional relationship is the same as that of the engine specification configuration.

[0091] <Placement within the hood> Let me explain the arrangement within the hood 130. When comparing the battery 80 and the fuel cell 90, the battery 80 generates less heat and has a smaller capacity. Therefore, placing the battery 80 in front of the work vehicle 10 improves visibility and allows for more efficient cooling water routing.

[0092] Furthermore, since the hydraulic system cooling radiator 111 is air-cooled, it is positioned immediately behind the coolant radiator device 120, allowing for cooling by suction air.

[0093] <Overall arrangement> In the third invention, a power rotation transmission mechanism case 30 is positioned between the left rear wheel 31, the right rear wheel 35, and the external power output shaft 38, and is connected to the hydrogen tank case 61 that fixes the hydrogen tank 60 and the hydrogen tank frames 52 and 52A that fix the hydrogen tank 50, and is positioned perpendicular to the rear wheel axle position 39 that connects the left rear wheel axle 32 and the right rear wheel axle 36, thus forming the vehicle body frame unit 70. On the upper side of the vehicle body frame unit 70, on the forward side with respect to the direction of travel, a battery 80 and a fuel cell unit 90 are positioned, and on the upper side of the vehicle body frame unit 70, on the rear side with respect to the direction of travel, a hydraulic unit 110 for raising and lowering work equipment is positioned between the upper part of the power rotation transmission mechanism case 30 and the operator's seat unit 40.

[0094] In the fourth invention, the fuel cell unit 90 has an electrolyte 91 in the center and is configured in layers through which cooling water, hydrogen, and air flow, with the orientation of the cooling water layer 92 parallel to the direction of travel of the work vehicle 10, and the cooling radiator 111 and battery 80 of the hydraulic unit 110 for lifting and lowering the work machine and the cooling water radiator device 120 are positioned in front of the direction of travel of the fuel cell unit 90, and the airflow from the cooling water radiator device 120 is exhausted from the ventilation opening 132 in front of the hood 130, and the cooling water radiator device 120 The cooling water is configured to pass through the cooling water radiator 121, the cooling pipe layer 81 of the battery 80, and the cooling water layer 92 of the fuel cell unit 90, flow over the top of the hydrogen tank 50, and circulate to the cooling water radiator device 120. This configuration allows for efficient cooling by circulating the cooling water with the high-temperature fuel cell at the rear, improves visibility during operation, and protects the fuel cell, which is at risk of damage if the work vehicle 10 collides with an obstacle, by positioning it in the center of the work vehicle 10.

[0095] <Configuration of hydrogen tank valves> The hydrogen tank 50 can switch between supplying hydrogen gas to gas pipe 55 and gas pipe 56 via a valve unit switching device 53. When supplied to gas pipe 55, it is used to supply the fuel cell 90, which generates electricity to operate the work vehicle 10. When supplied to gas pipe 56, it is used to fill the hydrogen tank with gas. During hydrogen gas filling, it is drawn in from a gas charger to a gas intake port 54 (shown only in block diagram 10) provided in the hood 130 of the work vehicle. The hydrogen gas drawn in through gas pipe 57 is switched to gas pipe 56 by the valve switching device 53.

[0096] Hydrogen tank 50 and hydrogen tank 60 are connected by piping and valves, and the supply and filling of hydrogen gas from hydrogen tank 50 and hydrogen tank 60 is possible by switching the valves.

[0097] In the case of hydrogen gas filling, valves 58 and 62 open, hydrogen gas flows into pipes 59, 64, and 63, and hydrogen gas fills hydrogen tank 60. Valve 62 has a detection function that, when a predetermined pressure is reached, sends a detection signal and closes valve 62, completing the gas filling of hydrogen tank 60. Subsequently, when the pressure detection function of valve 58 detects a predetermined pressure, it controls the closing of valve 58 and the closing of valve switching device 53 to pipe 56. This completes the filling of hydrogen gas into hydrogen tanks 50 and 60.

[0098] In the case of supplying hydrogen gas to the fuel cell 90, the valve switching device 53 opens the piping 55 side. The pressure detection function of valve 58 is constantly detecting pressure, and when it falls below a predetermined pressure, valves 58 and 62 are gradually opened, allowing hydrogen gas from the hydrogen tank 60 to flow through piping 63, piping 64, and piping 59, and supplied to the hydrogen tank 50. The hydrogen gas is supplied to the fuel cell 90 under the appropriate pressure, with the pressure adjusted by the valve switching device. The VCU 82 controls the hydrogen gas pressure adjustment valve in the fuel cell 90, ensuring that hydrogen gas is supplied according to the operating conditions.

[0099] The relative positions of valves, piping, hydrogen tanks, and operating units are shown in the cross-sectional views in Figures 2 and 6.

[0100] <Water discharge> Figure 8 shows the positional relationship between the front axle 20, the front wheel motor 29, and the water drain port 95 of the fuel cell 90. The drain port 95 exits from the separator section on the outside of the fuel cell 90, is located in the gap with the hood 130, and falls vertically to the ground without any obstacles. Therefore, there are no problems such as water droplets accumulating on the hydrogen tank 50 below. The fifth invention is implemented with this configuration.

[0101] Although not shown in the diagram, it is also possible to install an auxiliary tank beyond the drain outlet 95 to prevent watering the field.

[0102] <Front Axle> The front wheel motor 29 is located in the center, and the front axle houses a transmission mechanism, incorporating a transmission, clutch, differential gear, etc. The power from the front wheel motor 29 is reduced or increased and distributed to the left and right wheels, and rotational control is performed, including the differential function.

[0103] Figures 10 and 11 are block diagrams showing the relationships between each piece of equipment.

[0104] Electrical wiring is indicated by a medium line, hydrogen gas piping by a thick line, power transmission by a dashed-dot line, hydraulic systems by a medium-dash line, and cooling water by a double-dash line. Supplementary explanations are provided for parts not mentioned above.

[0105] Figure 10 is a block diagram of an embodiment of the present invention in which the left and right rear wheels and the PTO are operated by separate motors, while Figure 11 shows a configuration in which the rear wheels are electrically powered by a single motor, and power is distributed to the rear wheels and the PTO by a transmission case.

[0106] The left rear wheel electric motor 33, the right rear wheel electric motor 37, and the PTO electric motor 39 are operated by power supplied by the DC / DC converter 83 shown in Figure 10. Each motor has an MCU that controls the motor's instruction signals, rotation direction, and rotation speed. Each MCU contains a capacitor that instantly obtains the specified rotation direction. The arrangement of each component is as shown in the diagram.

[0107] Although it is referred to as the power rotation transmission mechanism case 30, in this case there is no transmission device such as gears, but it is a robust case that encloses the motor for the PTO and is connected to the hydrogen tank case 61 that holds the left and right rear wheel motors and the hydrogen tank 2.

[0108] The power supplied by the DC / DC converter 83 also provides power to the air conditioning motor 83, the hydraulic motor 112, and the front wheel motor 29. Each of these motors also has its own MCU, and rotational speed control and other functions are operated by control signals from the VCU 82 and BMS 81. Although this block diagram does not show the wiring for communication lines such as CAN lines, the basic signals from the VCU 82 cause the BMS 81 and the DC / DC converter 83 to work together, sending the appropriate voltage as needed, and allowing each MCU to perform appropriate control.

[0109] Figure 11 shows that the rear wheel motor 170 is located inside the power rotation transmission mechanism case 160, and power distribution, rotational speed control, and rotational direction switching are performed using internal gears, clutches, and reduction gears. Power is distributed in three directions, with the left rear axle output at 180, the right rear axle output at 190, and the PTO shaft output at 200. [Explanation of Symbols]

[0110] 10 Work Vehicles 20 Front Axle 30 Power Rotation Transmission Mechanism Case 40 Control Panel Unit 41 Foot position 42. Bottom position of the feet 50 hydrogen tanks 52 52A Hydrogen Tank Frame 60 hydrogen tanks 61 Hydrogen Tank Case 70 Frame Unit 80 batteries 85 Battery Cooling Case 90 Fuel Cell 92 Cooling water layer 110 Hydraulic Unit 120 Cooling water radiator system 130 Food< / vcu> < / mcu>

Claims

1. A work vehicle in which a hydrogen tank (50) is positioned above the front axle (20) connecting the left front wheel (21) and the right front wheel (25), parallel to the direction of travel, and the upper rear end (51) of the hydrogen tank (50) is positioned forward of the foot position (41) of the operator's seat unit (40) and above the bottom surface position (42) of the foot.

2. The work vehicle according to claim 1, wherein the hydrogen tank (60) is located behind the foot position (41) of the operator's seat unit (40) in the direction of travel, and below the bottom surface position (42) of the foot.

3. A power rotation transmission mechanism case (30) is positioned between the left rear wheel (31), the right rear wheel (35), and the external power output shaft (38). The hydrogen tank (60) is fixed to the hydrogen tank case (61) and the hydrogen tank frame (52, 52A) which fixes the hydrogen tank (50). It is positioned perpendicular to the axle position (39) of the rear wheels connecting the left rear axle (32) and the right rear axle (36), and constitutes the frame unit (70) of the vehicle body. A work vehicle according to claim 1 or 2, wherein a battery (80) and a fuel cell unit (90) are arranged on the upper side of the vehicle body frame unit (70), on the front side with respect to the direction of travel.

4. The fuel cell unit (90) has an electrolyte (91) in the center and is configured in layers through which cooling water, hydrogen, and air flow, with the cooling water layer (92) oriented parallel to the direction of travel of the work vehicle (10). The cooling radiator (111) and battery (80) of the hydraulic unit (110) for lifting and lowering the work equipment, and the cooling water radiator device (120) are positioned in front of the fuel cell unit (90) in the direction of travel. The airflow from the cooling water radiator device (120) is exhausted from the ventilation opening (132) at the front of the hood (130). The work vehicle according to claim 3, wherein the coolant of the coolant radiator device (120) passes through the coolant radiator (121), the cooling pipe layer (81) of the battery (80), and the cooling layer (92) of the fuel cell unit (90), flows over the top of the hydrogen tank (50), and circulates back to the coolant radiator device (120).

5. A work vehicle according to claim 3, wherein a drain port (95) for water discharged from the fuel cell unit (90) is provided between the frame unit (70) and the hood (130), and the water is discharged downwards to the work vehicle.

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