Work vehicle

Abstract

This work vehicle is provided with: a fuel cell module having a fuel cell stack; a motor connected to the fuel cell module; a traveling device driven by the motor; a control device for controlling the motor; and a positioning system. The control device changes the stop mode of the motor when a travel stop command is issued during the driving of the motor in accordance with whether or not the position of the work vehicle determined by the positioning system is in the field. The control device makes the time from the transmission of the travel stop command to the stop of the motor when the work vehicle is located in the field shorter than the time from the transmission of the travel stop command to the stop of the motor when the work vehicle is located outside the field.

Description

Technical Field

[0001] The present disclosure relates to a work vehicle. Background Art

[0002] In the automotive field, where the main purpose is to move "people" or "objects", electric vehicles (EVs) that use electric motors (hereinafter referred to as "motors") instead of internal combustion engines to generate driving force (traction) for traveling are becoming popular.

[0003] Meanwhile, achieving a decarbonized society also requires reducing the amount of carbon dioxide (CO2) emitted by work vehicles such as tractors used in farmland. Unlike conventional cars, work vehicles like tractors tow work implements, known as work tools, to perform agricultural work such as tilling. Therefore, electrifying work vehicles presents challenges that differ from those encountered with electrifying passenger vehicles.

[0004] Patent Document 1 discloses a tractor including a fuel cell (FC) power generation system and a motor without significantly changing the structure of a conventional engine-driven tractor.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-225577 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] The present disclosure provides a technology for improving stop control of a work vehicle equipped with a fuel cell module.

[0010] Means used to solve problems

[0011] One embodiment of the present invention relates to a work vehicle comprising: a fuel cell module having a fuel cell stack; a motor connected to the fuel cell module; a travel device driven by the motor; a control device controlling the motor; and a positioning system, wherein the control device changes the manner in which the motor stops when a travel stop instruction is issued during the driving of the motor, depending on whether the position of the work vehicle determined by the positioning system is within a field, and the control device makes the time from the issuance of the travel stop instruction to the stopping of the motor when the position of the work vehicle is within the field shorter than the time from the issuance of the travel stop instruction to the stopping of the motor when the position of the work vehicle is outside the field.

[0012] The inclusive or specific aspects of the present disclosure can be implemented using an apparatus, a system, a method, an integrated circuit, a computer program, or a computer-readable non-transitory storage medium, or any combination thereof. The computer-readable storage medium may include both volatile storage media and non-volatile storage media. The apparatus may also be composed of a plurality of apparatuses. In the case where the apparatus is composed of two or more apparatuses, the two or more apparatuses may be configured in one device or separately configured in two or more separate devices.

[0013] Effects of the Invention

[0014] According to the embodiment of the present disclosure, it is possible to improve the stopping control of a work vehicle equipped with a fuel cell module. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a plan view schematically showing a basic structural example of a work vehicle according to the present disclosure.

[0016] Figure 2 This is a diagram showing a basic configuration example of a fuel cell power generation system mounted on a work vehicle.

[0017] Figure 3 This is a block diagram schematically showing an example of electrical connection and power transmission between components of the work vehicle of the present disclosure.

[0018] Figure 4 It is a block diagram schematically showing the paths of electrical signals (thin solid lines) and the paths of coolant (dashed lines) between components in the work vehicle of the present disclosure.

[0019] Figure 5 It is a perspective view schematically showing a configuration example of a work vehicle in an embodiment of the present disclosure.

[0020] Figure 6 It is a side view schematically showing a configuration example of a work vehicle in an embodiment of the present disclosure.

[0021] Figure 7 This is a block diagram schematically showing a configuration example of a positioning system.

[0022] Figure 8 This is a flowchart showing a processing procedure of an example of the operation of the control device. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present disclosure. However, sometimes more detailed descriptions than necessary are omitted. For example, detailed descriptions of matters that are already known and repeated descriptions related to substantially the same structure are sometimes omitted. This is to avoid the following description from becoming unnecessarily lengthy and to make it easier for those skilled in the art to understand. In addition, the inventor provides the drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and does not intend to limit the subject matter described in the claims through them. In the following description, structural elements with the same or similar functions are marked with the same figure marks.

[0024] The following embodiments are provided as examples, and the technology disclosed herein is not limited to the following embodiments. For example, the numerical values, shapes, materials, steps, the order of these steps, and the layout of the display screen shown in the following embodiments are merely examples, and various modifications are possible as long as they do not create technical conflicts. Furthermore, any embodiment can be combined with another embodiment as long as they do not create technical conflicts.

[0025] The "work vehicle" in the present disclosure refers to a vehicle (vehicle) used to perform work at a work site. "Work site" refers to any place where work is performed, such as farmland, forest or construction site. "Field" refers to any place where agricultural work is performed, such as orchards, dry fields, paddy fields, grain farms or pastures. The work vehicle can be agricultural machinery such as a tractor, a rice transplanter, a combine harvester, a passenger management machine or a passenger lawn mower, or a vehicle used for non-agricultural purposes such as a construction work vehicle or a snowplow. The work vehicle in the present disclosure can be equipped with a work tool (also called a "work machine" or "work device") corresponding to the work content at at least one of its front and rear parts. Sometimes, driving a work vehicle while performing work is referred to as "work driving".

[0026] Furthermore, "agricultural machinery" refers to machinery used for agricultural purposes. Examples of agricultural machinery include tractors, harvesters, rice transplanters, passenger machines, vegetable transplanters, mowers, seed drills, fertilizer spreaders, and mobile agricultural robots. While individual work vehicles such as tractors may function as "agricultural machinery," the work tools attached to or towed by a work vehicle and the vehicle as a whole may also function as a single "agricultural machine." Agricultural machinery performs agricultural operations such as tilling the ground within fields, sowing seeds, pest control, fertilizing, and planting or harvesting crops.

[0027] "Autonomous driving" refers to the control of the movement of agricultural machinery through the operation of a control device rather than through manual operation by the driver. Agricultural machinery that performs autonomous driving is sometimes referred to as "autonomous agricultural machinery" or "robotic agricultural machinery." During autonomous driving, not only the movement of the agricultural machinery but also the movement of agricultural work (e.g., the movement of a work implement) can be automatically controlled. If the agricultural machinery is a vehicle-type machine, the movement of the agricultural machinery using autonomous driving is referred to as "autonomous driving." The control device is capable of controlling at least one of the steering required for the movement of the agricultural machinery, adjustment of the movement speed, and the start and stop of movement. In the case of a work vehicle equipped with a work implement, the control device may also control the raising and lowering of the work implement, the start and stop of the work implement, and other actions. Movement using autonomous driving can include not only the movement of the agricultural machinery toward a destination along a predetermined path, but also the movement of the agricultural machinery following a tracking target. Agricultural machinery that performs autonomous driving can move partially based on user instructions. In addition to autonomous driving mode, agricultural machinery that performs autonomous driving can also operate in a manual driving mode, where the movement is manually controlled by the driver. "Automatic steering" refers to the steering of agricultural machinery not manually but through the operation of a control device. Part or all of the control device may be external to the agricultural machinery. Communication of control signals, commands, or data, etc., can be performed between the control device located external to the agricultural machinery and the agricultural machinery. Autonomously driven agricultural machinery can also sense its surroundings and move autonomously without human intervention in controlling the movement of the agricultural machinery. Autonomously moving agricultural machinery can travel unmanned within a field or outside a field (e.g., on a road). During autonomous movement, obstacle detection and obstacle avoidance actions can be performed.

[0028] "Environmental map" is data that represents the position or area of ​​objects in the environment where agricultural machinery moves through a specified coordinate system. Sometimes the environmental map is simply referred to as a "map" or "map data". The coordinate system that specifies the environmental map can be, for example, a world coordinate system such as a geographic coordinate system fixed relative to the earth. Regarding objects existing in the environment, the environmental map can also include information other than the position (for example, attribute information and other information). Environmental maps include various forms of maps such as point group maps or raster maps. The data of local maps or partial maps generated or processed in the process of constructing the environmental map is also called "map" or "map data".

[0029] 1. <Basic structure of work vehicle>

[0030] The basic structure and operation examples of the work vehicle of the present disclosure will be described. The work vehicle described below is equipped with a motor and a fuel cell power generation system (hereinafter referred to as "FC power generation system") that generates electricity required to drive the motor.

[0031] Figure 1 This is a top view schematically showing an example of the basic structure of the work vehicle 100 of the present disclosure. In the present disclosure, the direction of travel when the work vehicle 100 is traveling straight forward is referred to as the "front direction", and the direction of travel when traveling straight backward is referred to as the "rear direction". In a plane parallel to the ground, the direction extending perpendicularly to the right relative to the "front direction" is referred to as the "right direction", and the direction extending perpendicularly to the left relative to the "front direction" is referred to as the "left direction". Figure 1 In the figure, the “front direction,” “rear direction,” “right direction,” and “left direction” are represented by arrows pointing to “front,” “rear,” “right,” and “left,” respectively. Sometimes, both the front direction and the rear direction are collectively referred to as the “front-rear direction.”

[0032] The work vehicle 100 in the illustrated example is, for example, a tractor, an example of agricultural machinery. The technology disclosed herein is not limited to work vehicles such as tractors and can also be applied to other types of work vehicles. Furthermore, the work vehicle 100 can travel within a field while carrying or towing a work tool and performing agricultural operations corresponding to the type of work tool. Furthermore, the work vehicle 100 can travel within a field and outside a field (including on roads) with or without the work tool.

[0033] Similar to conventional tractors, the work vehicle 100 has a vehicle body (vehicle frame) 102 that supports left and right front wheels 104F and left and right rear wheels 104R so as to be rotatable. The vehicle body 102 includes a front frame 102A provided with the front wheels 104F and a transmission case 102B provided with the rear wheels 104R. The front frame 102A is fixed to the front portion of the transmission case 102B. The front wheels 104F and the rear wheels 104R are sometimes collectively referred to as wheels 104. Strictly speaking, the wheels 104 are hubs with tires mounted thereon. In the present disclosure, "wheels" in principle refer to the whole of "hubs and tires." One or both of the front wheels 104F and the rear wheels 104R can be replaced by a plurality of wheels (tracks) mounted with an infinite track, instead of wheels with tires. In this specification, the left and right front wheels 104F, the left and right rear wheels 104R, the axles that rotate these four wheels, and the braking devices (brakes) that brake the axles may be collectively referred to as a "travel device."

[0034] Figure 1 In the example, work vehicle 100 includes a fuel cell module (FC module) 10 and a motor 70, which are directly or indirectly supported by a front frame 102A. FC module 10 includes a fuel cell stack (FC stack), which, as described later, functions as an onboard generator that generates electricity from fuel. Hereinafter, "FC module" or "FC stack" may be simply referred to as "fuel cell."

[0035] The motor 70 is electrically connected to the FC module 10. The motor 70 converts the electricity generated by the FC module 10 into mechanical motion (power), thereby generating the driving force (traction) required for the work vehicle 100 to travel. An example of the motor 70 is an AC synchronous motor. Since the FC stack of the FC module 10 generates DC current, if the motor 70 is an AC synchronous motor, a circuit assembly including an inverter device is provided between the FC stack and the motor 70 to convert the DC current into AC current. A portion of this circuit assembly can be located within the FC module 10. Alternatively, another portion of the circuit assembly can be mounted on the motor 70 as a drive circuit for the motor 70.

[0036] The motor 70 has a rotating output shaft 71. The torque of the output shaft 71 is transmitted to the rear wheel 104R via mechanical components such as the transmission (speed change device) and the rear wheel differential device (differential gear device) provided inside the transmission case 102B. In other words, the power generated by the motor 70 as a power source is transmitted to the rear wheel 104R via the power transmission system (power transmission system) 74 including the transmission provided in the transmission case 102B. Therefore, the "transmission case" can also be referred to as a "transmission box". In addition, in the four-wheel drive mode, part of the power of the motor 70 is also transmitted to the front wheel 104F. The power of the motor 70 can be used not only for the travel of the work vehicle 100, but also for driving the work tool. Specifically, a power take-off (PTO) shaft 76 is provided at the rear end of the transmission case 102B. The PTO shaft 76 is driven by the motor 70 and is connected to the work tool. The torque of the output shaft 71 of the motor 70 is transmitted to the PTO shaft 76. A work tool mounted on or towed by work vehicle 100 can receive power from PTO shaft 76 to perform various operations. Motor 70 and power transmission system 74 may also be collectively referred to as an electric powertrain.

[0037] Thus, the work vehicle 100 of the present disclosure is not equipped with an internal combustion engine such as a diesel engine, but rather with an FC module 10 and a motor 70. Furthermore, the output shaft 71 of the motor 70 is mechanically coupled to a power transmission system 74, such as a transmission, within the transmission case 102B. Compared to an internal combustion engine, the motor 70 can efficiently generate torque over a relatively wide speed range. However, by utilizing the power transmission system 74 including the transmission to perform multi-stage or stepless speed shifting, it is easier to adjust the torque and speed from the motor 70 over a wider range. Therefore, not only can the work vehicle 100 be efficiently driven, but also various operations using work tools can be efficiently performed.

[0038] In addition, depending on the use or size of the work vehicle 100, part of the functions of the power transmission system 74 may be deleted. For example, part or all of the transmission that undertakes the speed change function may be omitted. The number and mounting positions of the motors 70 are not limited to Figure 1 the example shown.

[0039] The work vehicle 100 has at least one fuel tank 50 that stores the fuel supplied to the FC module 10. In Figure 1 order to be concise, one fuel tank 50 is described. In some embodiments, a plurality of fuel tanks 50 are accommodated in a tank body to form a fuel tank module. As will be described later, the fuel tank 50 is supported by a member fixed to the vehicle body 102. The FC module 10 and the fuel tank 50 are connected by pipes, opening and closing valves, etc. to form an on-vehicle FC power generation system. The structure and operation of the FC power generation system will be described later.

[0040] The work vehicle 100 in the embodiments described later has a driver's seat supported by the vehicle body 102. The driver's seat may be surrounded by a cab supported by the vehicle body 102. In the embodiments described later, the FC module 10 is disposed in front of the driver's seat, and the fuel tank 50 is disposed above the driver's seat. Such an FC module 10 and fuel tank 50 are accommodated in at least one "accommodation body". The "accommodation body" functions as a housing, for example, to protect the FC module 10 and the fuel tank 50 from sunlight and the influence of wind and rain. In addition, when fuel gas leaks from the FC module 10 or the fuel tank 50, such an accommodation body can also control the diffusion of the fuel gas into the atmosphere, making it easier to detect the fuel gas.

[0041] The FC module 10 can be accommodated in a front housing called an "engine hood", for example. The front housing is part of the "accommodation body". The front housing is supported by the front part (front frame 102A) of the vehicle body 102. As described above, the fuel tank 50 can be accommodated in a tank body. The tank body is supported directly or indirectly by the vehicle body 102.

[0042] 2. <FC Power Generation System>

[0043] Next, refer to Figure 2 to describe a basic structural example of the FC power generation system 180 mounted on the work vehicle 100.

[0044] Figure 2 The FC power generation system 180 shown functions as an on-vehicle power generation system in the Figure 1 work vehicle 100. The electric power generated by the power generation of the FC power generation system 180 is used not only for the running of the work vehicle 100 but also for the operation of the work tools towed or mounted by the work vehicle 100.

[0045] The FC power generation system 180 in the illustrated example includes the FC module 10 and at least one fuel tank 50 for storing fuel supplied to the FC module 10. The FC power generation system 180 also includes a radiator device 34 for cooling the FC module 10.

[0046] The FC module 10 includes as its main components a fuel cell stack (FC stack) 11, an air compressor 12, a fuel circulation pump 24, a coolant pump 31, a boost circuit 40, and a control device 42. These components are housed within the housing of the FC module 10 and are interconnected by electrical or fluid communication.

[0047] The FC stack 11 generates electricity through an electrochemical reaction between "anode gas" as a fuel and "cathode gas" as an oxidizing gas. The FC stack 11 in this example is a solid polymer fuel cell. The FC stack 11 has a stacked structure in which a plurality of single cells (fuel cell cells) are stacked. The single cell has an electrolyte membrane formed by, for example, an ion exchange membrane, an anode formed on one side of the electrolyte membrane, a cathode formed on the other side of the electrolyte membrane, and a pair of separators that sandwich the anode and cathode from both sides. The voltage generated in the single cell is, for example, less than 1 volt. Therefore, in the FC stack 11, for example, more than 300 single cells are connected in series to generate a voltage of several hundred volts.

[0048] Anode gas is supplied to the anode of the FC stack 11. The anode gas is referred to as "fuel gas" or simply "fuel." In the embodiment of the present disclosure, the anode gas (fuel) is hydrogen. Cathode gas is supplied to the cathode. The cathode gas is an oxidizing gas such as air. The anode is referred to as the fuel electrode, and the cathode is referred to as the air electrode.

[0049] In the anode, the electrochemical reaction represented by the following formula (1) occurs.

[0050] 2H2→4H + +4e - …Formula (1)

[0051] In the cathode, the electrochemical reaction represented by the following formula (2) occurs.

[0052] 4H + +4e - +O2→2H2O…Formula (2)

[0053] As a whole, the reaction of the following formula (3) occurs.

[0054] 2H2+O2→2H2O…Formula (3)

[0055] The anode gas after being used in the above reaction is called "anode exhaust gas", and the cathode gas after being used in the reaction is called "cathode exhaust gas".

[0056] The air compressor 12 supplies air drawn in from the outside as cathode gas to the cathode of the FC stack 11. The cathode gas supply system including the air compressor 12 includes a cathode gas supply pipe 13, a cathode exhaust pipe 14, and a bypass pipe 15. The cathode gas supply pipe 13 allows the cathode gas (air) supplied from the air compressor 12 to flow to the cathode of the FC stack 11. The cathode exhaust pipe 14 allows the cathode exhaust discharged from the FC stack 11 to flow to the outside air. The bypass pipe 15 branches from the cathode gas supply pipe 13 downstream of the air compressor 12, bypasses the FC stack 11, and connects to the cathode exhaust pipe 14. A control valve 16 for adjusting the flow rate of the cathode gas flowing into the bypass pipe 15 is provided in the bypass pipe 15. A shut-off valve 17 for selectively shutting off the flow of cathode gas into the FC stack 11 is provided in the cathode gas supply pipe 13. A pressure regulating valve 18 for adjusting the back pressure of the cathode gas is provided in the cathode exhaust pipe 14.

[0057] The cathode gas supply system of the FC module 10 includes a rotation speed sensor S1 for detecting the rotation speed of the air compressor 12 and a gas flow rate sensor S2 for detecting the flow rate of the cathode gas flowing through the cathode gas supply pipe 13. The control valve 16, the shutoff valve 17, and the pressure regulating valve 18 are, for example, solenoid valves.

[0058] The fuel circulation pump 24 supplies fuel gas (anode gas) delivered from the fuel tank 50 to the anodes of the FC stack 11. The anode gas supply system including the fuel circulation pump 24 has an anode gas supply pipe 21, an anode exhaust pipe 22, and a circulation flow path 23. The anode gas supply pipe 21 allows the anode gas supplied from the fuel tank 50 to flow to the anodes of the FC stack 11. The fuel tank 50 in the embodiment of the present disclosure is a hydrogen tank that stores high-pressure hydrogen gas.

[0059] The anode exhaust gas pipe 22 is for the anode exhaust gas discharged from the FC stack 11 to flow. The anode exhaust gas is guided to the gas-liquid separation device 25 through the anode exhaust gas pipe 22 to remove moisture. The anode exhaust gas from which moisture has been removed is returned to the anode gas supply pipe 21 via the circulation flow path 23 by the fuel circulation pump 24. The anode exhaust gas circulating in the circulation flow path 23 can be discharged via the anode exhaust gas pipe 22 by opening the exhaust valve 26. The moisture stored in the gas-liquid separation device 25 can be discharged via the anode exhaust gas pipe 22 by opening the exhaust valve 26. The exhaust valve 26 is, for example, a solenoid valve. In the example of the figure, the anode exhaust gas pipe 22 is connected to the cathode exhaust gas pipe 14. By adopting such a structure, the anode exhaust gas containing unreacted anode gas that does not contribute to the electrochemical reaction is circulated and supplied to the FC stack 11 again, thereby improving the utilization efficiency of the anode gas.

[0060] In order to improve the performance of the FC stack 11, its temperature control is important. When electricity is generated by the reaction of hydrogen and oxygen to produce water, heat is also generated, so cooling is required. Figure 2While the FC module 10 includes a coolant circulation system including a coolant pump 31 for the FC stack 11, cooling circulation systems for other electrical components may also be provided, as described later. Furthermore, the air compressor 12, fuel circulation pump 24, and coolant pump 31 included in the FC module 10 are each operated by a built-in motor. These motors are also electrical components.

[0061] Figure 2 The coolant circulation system, including the coolant pump 31, has a coolant supply pipe 32, a coolant discharge pipe 33, a radiator device 34, and a temperature sensor S3. This coolant circulation system can regulate the temperature of the FC stack 11 within a predetermined range by circulating the coolant through the FC stack 11. The coolant is supplied to the FC stack 11 via the coolant supply pipe 32. The supplied coolant flows through the coolant flow path formed between the single cells and is discharged into the coolant discharge pipe 33. The coolant discharged from the coolant discharge pipe 33 flows into the radiator device 34. The radiator device 34 dissipates heat from the coolant by exchanging heat with the outside air, and then supplies the cooled coolant back to the coolant supply pipe 32.

[0062] The coolant pump 31 is installed in the coolant supply pipe 32 or the coolant discharge pipe 33 to deliver coolant to the FC stack 11. A coolant bypass flow path may be provided between the coolant discharge pipe 33 and the coolant supply pipe 32. In this case, a diverter valve is installed at the branch point where the coolant bypass flow path branches from the coolant discharge pipe 33. The diverter valve adjusts the flow rate of coolant flowing into the bypass flow path. A temperature sensor S3 detects the temperature of the coolant flowing in the coolant discharge pipe 33.

[0063] The coolant used to cool the FC stack 11 is circulated through the flow path by an electric coolant pump (coolant pump) 31. A coolant control valve may be provided downstream of the FC stack 11. The coolant control valve adjusts the ratio of coolant flowing to the radiator device 34 to coolant bypassing the radiator device 34, thereby enabling the coolant temperature to be controlled with greater accuracy. Furthermore, by controlling the water flow rate of the coolant pump, the coolant temperature difference between the inlet and outlet of the FC stack 11 can be controlled within a desired range. The coolant temperature in the FC stack 11 can be controlled to a temperature at which the power generation efficiency of the FC stack 11 is high, for example, approximately 70°C.

[0064] The coolant flowing through the FC stack 11 preferably has higher insulation properties than coolants typically used to cool electrical components. High voltages, such as those exceeding 300 volts, are generated in the FC stack 11. Therefore, increasing the coolant's electrical resistance can suppress current leakage through the coolant or the radiator 34. As the coolant is used, its electrical resistance sometimes decreases. This is because ions dissolve into the coolant flowing through the FC stack 11. To remove these ions from the coolant and improve its insulation, an ion exchanger is preferably placed in the coolant flow path.

[0065] The boost circuit 40 raises the voltage output from the FC stack 11 during power generation to a desired level. The downstream stage of the boost circuit 40 is connected to a circuit in the high-voltage system, including an inverter device for driving the motor. Alternatively, the downstream stage of the boost circuit 40 can be connected in parallel to a circuit in the low-voltage system via a step-down circuit.

[0066] The control device 42 is an electronic control unit (ECU) that controls power generation by the FC module 10. The control device 42 detects or estimates the operating status of the FC power generation system 180 based on signals output from various sensors. Based on the operating status of the FC power generation system 180 and instructions output from a higher-level computer or other ECU, the control device 42 controls the operation of the air compressor 12, fuel circulation pump 24, coolant pump 31, and various valves, thereby controlling power generation by the FC stack 11. The control device 42 includes, for example, a processor, a storage device, and an input / output interface.

[0067] In the following description, for simplicity, “anode gas” is referred to as “fuel gas” or “fuel”, and “anode gas supply pipe” is referred to as “pipe”.

[0068] 3. <System Configuration Example of Work Vehicle>

[0069] Next, refer to Figure 3 and Figure 4 , an example of the system configuration of the work vehicle 100 is described. Figure 3 This is a block diagram schematically showing an example of electrical connection and power transmission between components of the work vehicle 100 of the present disclosure. Figure 4 It means ratio Figure 3 A more detailed structural block diagram is shown in the structural example. Figure 4 Schematically shows the paths of electrical signals (thin solid lines) and the paths of coolant (dashed lines) between components in work vehicle 100 .

[0070] First, refer to Figure 3This section describes examples of electrical connections and power transmission between components. Electrical connections include both high-voltage and low-voltage systems. For example, high-voltage system connections provide power supply voltage for inverter devices. For example, low-voltage system connections provide power supply voltage for electronic components that operate at relatively low voltages.

[0071] exist Figure 3 In the example shown, the work vehicle 100 includes an FC module 10, an inverter device 72, a motor 70, a power transmission system 74, and a PTO shaft 76. The DC voltage of the power generated by the FC stack 11 of the FC module 10 is supplied to the inverter device 72 after being boosted by the boost circuit 40. The inverter device 72 converts the DC voltage into, for example, a three-phase AC voltage and supplies it to the motor 70. The inverter device 72 has a bridge circuit including a plurality of power transistors. The motor 70 includes a rotating rotor and a stator having a plurality of coils electrically connected to the inverter device 72. The rotor is coupled to the output shaft 71, for example, via a reduction gear (reducer) or directly. The motor 70 rotates the output shaft 71 at a torque and a rotational speed that are controlled according to the waveform of the three-phase AC voltage from the inverter device 72.

[0072] Work vehicle 100 also includes a control unit (ECU) 72A that controls motor 70. Control unit 72A is connected to inverter 72 and controls the switching (on / off) of each of the plurality of power transistors included in the bridge circuit of inverter 72. Control unit 72A can be connected to inverter 72 via a pre-driver (sometimes referred to as a "gate driver"). Control unit 72A can operate under the control of a host computer.

[0073] The torque of the output shaft 71 of the motor 70 is transmitted to the power transmission system 74. The power transmission system 74 operates with the motor 70 as the power source and can drive Figure 1 wheels 104R, 104F and / or PTO shaft 76. Such a power transmission system 74 may have the same structure as or a similar structure to a power transmission system in a conventional tractor including an internal combustion engine such as a diesel engine. For example, by adopting a power transmission system used in agricultural tractors, etc., it is possible to suppress the design cost and manufacturing cost of manufacturing a work vehicle 100 for agricultural use equipped with an FC power generation system. The power transmission system 74 includes: a travel system power transmission mechanism that transmits power from the motor 70 to the left and right rear wheels 104R via a clutch, a transmission, and a rear wheel differential device; and a PTO system power transmission mechanism that transmits power from the motor 70 to the PTO shaft 76. Figure 1 The transmission case 102B can also be divided into a front case (transmission case) that houses a clutch and a transmission, etc., and a rear case (differential gear case) that houses a rear wheel differential device, etc. The rear case is also called a rear axle case.

[0074] The work vehicle 100 includes a secondary battery (battery pack) 80 that temporarily stores the electrical energy generated by the FC module 10. Examples of the battery pack 80 include a lithium-ion battery pack. The battery pack 80 is electrically connected to the FC module 10 and to the motor 70 via the inverter 72. The battery pack 80 can supply power to the inverter 72 when needed, either in conjunction with the FC module 10 or independently. Various battery packs used in passenger electric vehicles can be employed as the battery pack 80. Hereinafter, the battery pack 80 may be simply referred to as "battery 80."

[0075] In addition to the motor 70 and the inverter device 72, the work vehicle 100 also has various electrical components (on-board electronic components) that are operated by electricity. Examples of electrical components include solenoid valves such as the on-off valve 20, the air-cooling fan of the radiator device 34, the electric pump of the refrigeration compressor 85, and a temperature control device for heating or cooling the FC stack 11. Such a temperature control device includes an electric heater 86. In addition, the first DC-DC converter 81 and the second DC-DC converter 82 for obtaining a power supply voltage suitable for the operation of these electrical components, and the battery 83 may also be included in the electrical components. Moreover, various electronic components not shown (lights, electric motors for hydraulic systems, etc.) may also be included in the electrical components. These electrical components may be, for example, the same electronic components as those of conventional agricultural tractors.

[0076] exist Figure 3 In the example, the first DC-DC converter 81 is a circuit that steps down the voltage output from the boost circuit 40 of the FC module 10 to a first voltage, for example, 12 volts. The battery 83 is, for example, a lead-acid battery, and can store electrical energy using the voltage output from the first DC-DC converter 81. The battery 83 can be used as a power source for various electrical components, such as lamps.

[0077] Figure 3 The work vehicle 100 shown has not only a first DC-DC converter 81 but also a second DC-DC converter 82 as a voltage conversion circuit for reducing the high voltage output by the FC module 10. The second DC-DC converter 82 is a circuit that reduces the voltage output by the boost circuit 40 of the FC module 10 (e.g., several hundred volts) to a second voltage higher than the first voltage, e.g., 24 volts. For example, the air cooling fan of the radiator device 34 can be operated by the voltage output by the second DC-DC converter 82. Figure 3 , a single component is described, but a plurality of radiator devices 34 may be provided on a single work vehicle 100. In addition, the electric pump of the cooling compressor 85 and the electric heater 86 can also be operated using the voltage output from the second DC-DC converter 82.

[0078] Figure 3 The work vehicle 100 shown has a temperature control device for cooling or heating the FC stack 11 included in the FC power generation system. The operation of such a temperature control device requires relatively large amounts of electricity. The relatively high voltage of 24 volts output by the second DC-DC converter 82 is supplied to such a temperature control device. The temperature control device in this embodiment includes a radiator device 34 for dissipating heat from the refrigerant cooling the FC stack 11, and the relatively high voltage of 24 volts (second voltage) output by the second DC-DC converter 82 is supplied to the radiator device 34. The temperature control device includes a heater 86 for heating the FC stack 11. The relatively high voltage output by the second DC-DC converter 82 can also be supplied to the heater. The relatively high voltage output by the second DC-DC converter 82 can also be supplied to an air conditioning device such as a refrigeration compressor 85.

[0079] Furthermore, work vehicle 100 may include a third voltage conversion circuit that converts the high voltage output by FC module 10 into a third voltage higher than the second voltage. The third voltage is, for example, 48 volts. If work vehicle 100 includes a motor other than motor 70, the third voltage may be used as a power source for the other motor.

[0080] Agricultural vehicles equipped with fuel cell power generation systems have electrical components required for fuel cell power generation in addition to those required for agricultural work. Therefore, the voltages appropriate for each electrical component may vary. According to embodiments of the present disclosure, an appropriate voltage can be supplied.

[0081] exist Figure 3 In the example shown, multiple fuel tanks 50 are housed within a tank housing 51. The fuel tanks 50 are connected to a filling port (fuel filling port) 52 for external fuel filling. This connection is established via piping 21 for flowing fuel gas. Furthermore, the fuel tanks 50 are connected to the FC module 10 via piping 21 equipped with an on-off valve 20. When hydrogen is used as the fuel gas, these piping 21 can be formed from a material highly resistant to hydrogen embrittlement, such as austenitic stainless steel such as SUS316L.

[0082] The tank housing 51 is provided with a valve space 53, in which various valves, including a pressure reducing valve, are arranged. The piping 21 connects the fuel tank 50 and the FC module 10 via the various valves provided in the valve space 53. Fuel gas, whose pressure has been reduced by the pressure reducing valve, flows through the piping 21 connecting the tank housing 51 and the FC module 10. If the fuel gas is hydrogen, the fuel tank 50 can be filled with high-pressure hydrogen, for example, at 35 MPa or higher. However, after passing through the pressure reducing valve, the hydrogen can be decompressed to, for example, approximately 2 atmospheres or less.

[0083] Next reference Figure 4 .exist Figure 4 In addition to Figure 3 In addition to the description of , a plurality of ECUs and a user interface 1 that communicate within the work vehicle 100 are also described. The communication can be performed via a CAN bus wiring or the like that serves as a path (thin solid line) for electrical signals. Figure 4 The cooling system for achieving thermal management of the components is also described. Specifically, the path of the cooling liquid is schematically shown (dashed line).

[0084] As mentioned above, the first DC-DC converter 81 and the second DC-DC converter 82 can each output voltages of different magnitudes. An ECU that controls the respective voltage conversion circuits is also provided in the first DC-DC converter 81 and the second DC-DC converter 82. Similar to the other ECUs, the relatively low first voltage output by the first DC-DC converter 81 is provided to these ECUs.

[0085] exist Figure 4 In the example, the work vehicle 100 has a cooling system that circulates the coolant using coolant pumps 31A and 31B. These coolant pumps 31A and 31B are arranged inside the FC module 10. The cooling system in this example includes a first radiator device 34A that is responsible for cooling the FC stack 11 and a second radiator device 34B that is responsible for cooling other electrical components. The cooling system has a flow path (first flow path) for the coolant to flow between the FC stack 11 and the first radiator device 34A. In addition, the cooling system has a flow path (second flow path) for the coolant to flow between the electrical components including the motor 70 and the second radiator device 34B. In addition, in Figure 4 In the example of FIG. 8 , for example, a heater core 87 for heating the cabin is provided, and the coolant flowing through the first radiator device 34A flows through the heater core 87 .

[0086] The user interface 1 includes an operating device 2, such as an accelerator pedal (or accelerator lever), and a main ECU 3 connected to the operating device 2. The main ECU 3 is communicatively connected to a main meter 4, a storage device 7, a positioning system 8, and the like via a bus. The storage device 7 and the positioning system 8 will be described later. The main meter 4 can display various parameters that determine the driving state or operating state of the work vehicle 100. The user interface 1 also includes an FC system ECU 5 for controlling the FC power generation system. The FC system ECU 5 is connected to an FC meter 6. The FC meter 6 can display various parameters that determine the operating state of the FC power generation system.

[0087] The storage device 7 includes one or more storage media, such as flash memory or magnetic disks. The storage device 7 stores various data generated by the main ECU 3 and the FC system ECU 5. The storage device 7 also stores computer programs that cause the main ECU 3 and the FC system ECU 5 to perform desired operations. Such computer programs can be provided to the work vehicle 100 via a storage medium (e.g., a semiconductor memory or optical disk) or a telecommunications line (e.g., the Internet). Such computer programs can be sold as commercial software.

[0088] Work vehicle 100 may further include a positioning system 8. Positioning system 8 includes, for example, a GNSS (Global Navigation Satellite System) receiver for positioning and an external sensor for sensing conditions outside work vehicle 100. An example of the block structure of positioning system 8 will be described later.

[0089] The cells in battery pack 80 are controlled by a battery management unit (BMU). The BMU includes a voltage monitor for each cell, circuits for monitoring overcharge and overdischarge, cell balancing control, and a CPU (Central Processing Unit). These circuits and the CPU can be mounted on a battery controller board.

[0090] 4. <Implementation Method>

[0091] (4.1. Basic structure of work vehicle)

[0092] Next, refer to Figure 5 and Figure 6 , the basic structure of an embodiment of the work vehicle disclosed in the present invention is described. Figure 5 It is a perspective view schematically showing a configuration example of a work vehicle 200 in this embodiment. Figure 6 It is a side view schematically showing a configuration example of a work vehicle 200 in this embodiment.

[0093] The work vehicle 200 in this embodiment includes an FC module 10, a fuel tank 50, a motor 70, a driver's seat 107, a vehicle body 102, a control device, and a travel device. Figure 1 The structure is the same as that of the work vehicle 100 described above.

[0094] In the following description, the multiple ECUs involved in controlling the work vehicle 200 system, including the main ECU 3, the FC system ECU 5, and the ECU 72A, are collectively referred to as the "control device." Each ECU includes a storage device (ROM) and may also include, for example, an FPGA (Field Programmable Gate Array) and / or a GPU (Graphics Processing Unit). A single ECU, or multiple ECUs working together, communicate with a host computer and sequentially execute a computer program containing a set of commands for executing at least one process stored in the storage device to perform the desired actions.

[0095] The work vehicle 200 in this embodiment further includes a positioning system 8 (see Figure 4 ) and an operation terminal 400. The operation terminal 400 is a terminal for a user to perform operations related to the travel of the work vehicle and the operation of the work tool, and is also called a virtual terminal (VT). The operation terminal 400 may include a touch screen display device and / or one or more buttons. The display device may be a display such as a liquid crystal or an organic light emitting diode (OLED).

[0096] Figure 7 It is a block diagram schematically showing a configuration example of the positioning system 8 . Figure 7 The illustrated positioning system 8 includes a GNSS receiver 8A, an external sensor 8B, and a self-position estimation device 8C. The positioning system 8 may also include an RTK (Real Time Kinematic) receiver and an inertial measurement unit (IMU).

[0097] GNSS receiver 8A includes, for example, an antenna and a GNSS receiver. GNSS receiver 8A receives satellite signals transmitted from a plurality of GNSS satellites and generates GNSS signals based on the satellite signals. GNSS data is generated in a predetermined format, such as NMEA-0183. The GNSS data may include, for example, the identification number of each satellite from which the satellite signal was received, as well as elevation, azimuth, and reception strength values.

[0098] The external sensor 8B outputs sensor data indicating the distribution of features around the work vehicle 200. Examples of the external sensor include a LiDAR sensor, a camera (or image sensor), a laser rangefinder (also called a "range-finding sensor"), an ultrasonic sensor, a millimeter-wave radar, and a magnetic sensor.

[0099] The self-position estimating device 8C is a device that uses the sensor data output from the external sensor 8B to estimate the position and orientation of the work vehicle 200 (self-position estimation). For self-position estimation, algorithms such as SLAM can be used, for example. The self-position estimating device 8C can be implemented using an ECU. The self-position estimating device 8C in this embodiment estimates the position of the work vehicle 200 by matching the sensor data output from the external sensor 8B with the environmental map. Matching can be performed using any matching algorithm such as NDT (Normal Distribution Transform) or ICP (Iterative Closest Point).

[0100] In this embodiment, the fuel tank 50 is supported by a fixing frame 120. The fixing frame 120 is fixed to the vehicle body 102 across the driver's seat 107. The fuel tank 50 is located above the driver's seat 107. However, the installation location of the fuel tank 50 is not limited to the example shown in the figure, and may be located inside the front housing 110, for example.

[0101] In this embodiment, the fixed frame 120 is a longitudinally axial structure such as a pipe fixed to the vehicle body 102. The fixed frame 120 includes two frames located on the left and right sides of the work vehicle 200 (see FIG. Figure 5 The front portion of the fixing frame 120 has a curved shape. The shape of the fixing frame 120 shown in the figure is merely an example, and the shape of the fixing frame 120 is not limited to this example.

[0102] In this embodiment, the vehicle body 102 has: a front frame 102A, which supports the front wheel 104F so as to be able to rotate; and a transmission box 102B, which supports the rear wheel 104R so as to be able to rotate. One end (front end) of the fixed frame 120 is fixed to the front frame 102A. The other end (rear end) of the fixed frame 120 is fixed to the transmission box 102B. Depending on the material of the fixed frame 120, these fixations can be performed by appropriate methods such as welding or bolting. The fixed frame 120 can be formed of, for example, metal, synthetic resin, carbon fiber or a composite material such as carbon fiber reinforced plastic or glass fiber reinforced plastic. The transmission box 102B includes a rear axle box, and the rear end of the fixed frame 120 can be fixed to the rear axle box. In addition, in the case where the fixed frame 120 is formed of metal, part or all of its surface may also be covered with a synthetic resin.

[0103] like Figure 6 As shown, the work vehicle 200 has a cab 105 surrounding a driver's seat 107 between a vehicle body 102 and a fixed frame 120. The driver's seat 107 is located in the rear part of the interior of the cab 105. In front of the driver's seat 107, a steering wheel (steering wheel) 106 for changing the direction of the front wheel 104F and an operation terminal 400 are provided. The cab 105 has a cab frame constituting a skeleton. A roof 109 is provided on the upper part of the cab frame. The cab frame of this embodiment is a four-column type. The cab 105 is supported on the transmission box 102B of the vehicle body 102, for example, via an anti-vibration mount. Refer to Figure 4 The user interface 1 described above is provided inside the cab 105. The cab 105 does not directly support the fuel tank 50, and therefore does not need to be particularly strengthened, and a cab used for a conventional tractor can be adopted.

[0104] The work vehicle 200 has a mounting platform 51A connecting the left side frame 120 and the right side frame 120. The fuel tank 50 can be arranged on the mounting platform 51A. In the case where there are multiple fuel tanks 50, the multiple fuel tanks 50 can be arranged in the fuel tank module 55. Figure 6 As shown, the fuel tank module 55 includes a tank case 51 that accommodates a plurality of fuel tanks 50. The left and right fixing frames 120 may be connected to each other by a member other than the mounting table 51A.

[0105] A connecting device 108 is provided at the rear end of the vehicle body 102, i.e., the rear end of the transmission case 102B. The connecting device 108 includes, for example, a three-point support device (also called a "three-point link" or a "three-point hook"), a PTO shaft, a universal joint, and a communication cable. The connecting device 108 can be used to load and unload the working tool 300 relative to the working vehicle 200. The connecting device 108 can, for example, raise and lower the three-point link through a hydraulic device to change the position or posture of the working tool 300. In addition, power can be transmitted from the working vehicle 200 to the working tool 300 via the universal joint. The working vehicle 200 can tow the working tool 300 and enable the working tool 300 to perform a prescribed operation (agricultural operation). The connecting device 108 can also be provided at the front of the vehicle body 102. In this case, the working tool 300 can be connected in front of the working vehicle 200.

[0106] The work tool 300 includes, for example, a drive device, a control device, and a communication device. The drive device performs the actions required for the work tool 300 to perform a predetermined task. The drive device includes, for example, a hydraulic device, an electric motor, or a pump, depending on the purpose of the work tool 300. The control device controls the actions of the drive device. The control device causes the drive device to perform various actions in response to signals transmitted from the work vehicle 200 via the communication device. Furthermore, the communication device can also transmit signals corresponding to the status of the work tool 300 to the work vehicle 200.

[0107] Figure 6 The work tool 300 shown is a rotary tiller, but the work tool 300 is not limited to a rotary tiller. For example, any work tool such as a planter (seeder), a spreader (fertilizer), a transplanter, a mower (mower), a spike harrow, a baler (grass collector), a harvester (reaper), a sprayer, or a rake can be connected to the work vehicle 200 for use.

[0108] Figure 6 The work vehicle 200 shown is capable of both manned and unmanned operation, but may also be capable of operating only unmanned. In this case, components required only for human operation, such as the cab 105, steering wheel 106, and driver's seat 107, may not be provided on the work vehicle 200. Unmanned work vehicle 200 can operate autonomously or under remote control by a user.

[0109] A work vehicle may have an autonomous driving function. That is, the work vehicle can travel by operating a control device, rather than manually. The work vehicle 200 in this embodiment can operate in both manual and autonomous driving modes. In autonomous driving mode, the work vehicle 200 can operate unmanned. Unmanned work vehicle 200 can travel autonomously or through remote control by a user.

[0110] Work vehicle 200 can operate autonomously both within a field and outside of a field (e.g., on a road). When operating autonomously, the control device can collaborate with positioning system 8 to perform calculations and controls to achieve autonomous operation. In other words, the control device can control the autonomous driving of work vehicle 200 based on the estimated position of work vehicle 200.

[0111] An example of automatic travel control of a work vehicle is described in detail in Japanese Patent Application No. 2022-097611, which is not yet published by the present applicant. The entire disclosure of Japanese Patent Application No. 2022-097611 is incorporated herein by reference.

[0112] (4.2. Stop control of work vehicles)

[0113] The control device in this embodiment changes the manner in which motor 70 is stopped when a travel stop command is issued while motor 70 is being driven, depending on whether work vehicle 200, as determined by positioning system 8, is within a field. Specifically, the control device shortens the time from issuance of the travel stop command to motor 70 stopping when work vehicle 200 is within a field compared to the time from issuance of the travel stop command to motor 70 stopping when work vehicle 200 is outside a field.

[0114] When work vehicle 200 is outside a field, the time from when the travel stop command is issued until motor 70 stops is referred to as the "first stop time." When work vehicle 200 is inside a field, the time from when the travel stop command is issued until motor 70 stops is referred to as the "second stop time." The second stop time is shorter than the first stop time.

[0115] In this embodiment, the travel stop instruction (or command) can be issued, for example, from the FC system ECU 5 or a higher-level computer communicating with the FC system ECU 5 to the main ECU 3 or the ECU 72A that controls the driving of the motor 70. Alternatively, the travel stop instruction can be issued from the main ECU 3 to the ECU 72A.

[0116] The FC meter 6 can display indicators indicating the operating status of the FC power generation system 180. The display on the FC meter 6 may include, for example, an indicator indicating an abnormality in the FC power generation system 180 and an indicator of a water temperature gauge indicating the status of the radiator device (e.g., the temperature measured by the temperature sensor S3).

[0117] The fuel tank 50 may be provided with a pressure sensor for measuring the remaining amount of fuel in the fuel tank 50. Furthermore, a temperature sensor for measuring the temperature within the fuel tank 50 may also be provided. For example, the FC system ECU 5 acquires sensor data output from the temperature sensor of the fuel tank 50 and measures the temperature of the fuel tank 50 based on the sensor data. Furthermore, the FC system ECU 5 acquires sensor data output from the pressure sensor of the fuel tank 50 and measures the pressure (residual pressure) of the fuel within the fuel tank 50 based on the sensor data.

[0118] The FC system ECU 5 determines whether the temperature and fuel pressure of the fuel tank 50 are within normal ranges. If either the temperature or the fuel pressure of the fuel tank 50 is outside the normal range, the FC system ECU 5 may, for example, illuminate or flash an indicator indicating an abnormality in the FC power generation system 180. For example, a stop button for emergency stopping the autonomously traveling work vehicle 200 may be displayed on the screen of the operation terminal 400. When the driver, seated in the driver's seat 107, notices the illumination or flashing of the indicator and presses the stop button or a switch located in the cab 105, the main ECU 3, for example, responds to the press by issuing a travel stop command to the ECU 72A. In response to the travel stop command, the ECU 72A stops the motor 70.

[0119] As another example, if a user performing remote operation using a terminal device presses a stop button displayed on the terminal device, the main ECU 3 can, for example, issue a travel stop command to ECU 72A in response to the press. Alternatively, the FC system ECU 5 can also issue a travel stop command to ECU 72A, for example, when an abnormality in the FC power generation system 180 is detected. ECU 72A stops the motor 70 in response to the travel stop command. Thus, in this embodiment, when an abnormality in the FC power generation system 180 is primarily detected during the driving of the motor 70, a travel stop command is issued for emergency stopping. However, the issuance of a travel stop command is not limited to when an abnormality in the FC power generation system occurs. A travel stop command can be issued when the stop button is pressed. Alternatively, when an obstacle is detected by the positioning system during autonomous driving in a field, for example, a travel stop command can be issued to stop the work vehicle on the spot.

[0120] like Figure 3 As shown, the work vehicle 200 in this embodiment includes a first switch R1 provided in the current path between the FC module 10 and the motor 70. The work vehicle 200 may also include a second switch R2 provided in the current path between the battery 80 and the motor 70. Examples of the first and second switches R1 and R2 are relays. The on / off control of the first and second switches R1 and R2 is performed, for example, by the FC system ECU 5. By turning off the first switch R1, the power supply from the FC module 10 to the motor 70 is cut off. By turning off the second switch R2, the power supply from the battery 80 to the motor 70 is cut off.

[0121] Figure 8 This is a flowchart showing a processing procedure of an example of the operation of the control device.

[0122] The control device cooperates with the positioning system 8 and executes control of automatic driving based on the sensor data output from the positioning system 8 (step S110).

[0123] For example, suppose the driver or user notices an abnormality in FC power generation system 180 and presses a stop button displayed on the screen of operation terminal 400 or a terminal device. In this case, a driving stop command is issued in response to the press (step S120), and the control device proceeds to the next step, step S130. The control device continues automatic driving control until the driving stop command is issued (step S120: "No", step S110).

[0124] In response to a travel stop command issued during the operation of motor 70, the control device determines whether the position of work vehicle 200, as determined by positioning system 8, is within or outside the field (step S130). The aforementioned storage device 7 can also store an environmental map of an area including one or more fields. In this embodiment, for example, in an environment where reception of satellite signals transmitted from GNSS satellites is good or relatively good, GNSS receiver 8A of positioning system 8 performs positioning. In an environment where reception is poor, self-position estimation device 8C estimates its own position, thereby determining or estimating the position of work vehicle 200.

[0125] The control device determines whether work vehicle 200 is inside or outside the field based on the position determined by positioning system 8 and the environmental map stored in storage device 7. The control device obtains, for example, position data generated by GNSS receiver 8A indicating the position of work vehicle 200. The position data includes information on the geographic coordinates of work vehicle 200. The geographic coordinate information includes, for example, latitude and longitude.

[0126] The environmental map stored in the storage device 7 includes information on the geographic coordinates of the areas shown on the map. For example, the environmental map may include a plurality of division polygons corresponding to a plurality of areas, and may also include attribute data indicating the attributes of features within each area. Each of the plurality of division polygons is defined by geographic coordinates.

[0127] The control device uses the environmental map to identify the area corresponding to the geographical coordinates indicated by the identified position data of work vehicle 200. The identified area corresponds to the area where work vehicle 200 is located. In this way, the control device can determine whether the area corresponding to the geographical coordinates indicated by the position data is inside or outside the field.

[0128] If the work vehicle 200 is located within a field ("Yes" in step S130), the control device stops the motor 70 after the second stop time following the travel stop command. For example, the control device stops the motor 70 by opening the first switch R1 (step S140). If the work vehicle 200 is located within a field, the control device may also stop the motor 70 by opening the first switch R1 and the second switch R2 in response to the travel stop command. In contrast, if the work vehicle 200 is located outside a field ("No" in step S130), the control device stops the motor 70 after the first stop time following the travel stop command (step S150). In other words, after receiving the travel stop command, the control device maintains the motor drive for a predetermined time (e.g., the first stop time) and then stops the motor 70. After receiving the travel stop command, the power supply to the motor 70 may be maintained for a predetermined time.

[0129] When work vehicle 200 is located outside a field, the control device can perform the following actions instead of opening the switches. For example, upon receiving a travel stop command, ECU 72A may cease control of inverter unit 72 after a first stop time has elapsed. Alternatively, upon receiving a travel stop command, FC system ECU 5 may instruct control device 42 of FC module 10 to cease power generation after the first stop time has elapsed, thereby halting power generation by FC module 10.

[0130] In this manner, when a travel stop command is issued during automatic travel control, the control device stops motor 70 at different timings depending on whether or not the position of work vehicle 200 is within a field.

[0131] According to the stop control of a work vehicle in this embodiment, for a work vehicle traveling or working in a field, for example, the control device, in response to an emergency stop instruction, opens the first switch to immediately cut off the power supply to the motor, thereby stopping the motor. This allows the work vehicle traveling or working in a field to be brought to an immediate emergency stop. Furthermore, for example, the control device, in response to an emergency stop instruction, opens the first and second switches to immediately and completely cut off the power supply to the motor, thereby appropriately stopping the motor.

[0132] For a work vehicle traveling outside a field, after receiving a travel stop command, the control device maintains motor drive only for the first stop time, allowing the work vehicle to continue traveling. In other words, the control device does not immediately shut off power to the motor in response to the travel stop command. This allows, for example, the work vehicle to be moved to the side of a road. Alternatively, after moving the work vehicle to the side of the road, the control device may turn off the first and / or second switches to stop the motor. This allows the work vehicle to be parked in a safe location.

[0133] The work vehicle in this embodiment is not limited to automatic driving. Specifically, even when the work vehicle is manually driven, if a travel stop command is issued while the motor is being driven, i.e., while the work vehicle is traveling, the control device can stop the motor at different timings depending on whether the work vehicle is located within a field.

[0134] The configuration and operation of the above-described embodiment are merely illustrative, and the present disclosure is not limited to the above-described embodiment. For example, the above-described various embodiments may be appropriately combined to form other embodiments.

[0135] As described above, the present disclosure includes the work vehicles described in the following items.

[0136] [Project 1]

[0137] A work vehicle,

[0138] have:

[0139] A fuel cell module having a fuel cell stack;

[0140] a motor connected to the fuel cell module;

[0141] a traveling device, driven by the motor;

[0142] a control device for controlling the motor; and

[0143] Positioning system, where

[0144] The control device changes the manner in which the motor is stopped when a travel stop command is issued while the motor is being driven, depending on whether the position of the work vehicle determined by the positioning system is within a field.

[0145] The control device shortens the time from issuance of the travel stop command to motor stop when the work vehicle is located within a field, compared to the time from issuance of the travel stop command to motor stop when the work vehicle is located outside a field.

[0146] [Project 2]

[0147] The work vehicle according to item 1, wherein:

[0148] The work vehicle further includes a first switch provided on a current path between the fuel cell module and the motor.

[0149] The control device responds to a travel stop instruction issued during driving of the motor,

[0150] determining whether the position of the work vehicle determined by the positioning system is inside or outside the field,

[0151] When the work vehicle is located in a field, the motor is stopped by turning off the first switch.

[0152] When the work vehicle is located outside a field, the motor is stopped after the driving of the motor is maintained for a predetermined time after receiving the travel stop command.

[0153] [Item 3]

[0154] The work vehicle according to item 2, wherein:

[0155] The work vehicle also has:

[0156] a battery connected to the fuel cell module and the motor; and

[0157] a second switch, provided on a current path between the battery and the motor;

[0158] When the work vehicle is located in a field, the control device turns off the first switch and the second switch in response to the travel stop instruction to stop the motor.

[0159] [Item 4]

[0160] The work vehicle according to any one of items 1 to 3, wherein

[0161] The positioning system includes a GNSS receiver.

[0162] [Item 5]

[0163] The work vehicle according to any one of items 1 to 4, wherein

[0164] The work vehicle further includes a storage device storing an environmental map of an area including one or more fields.

[0165] The control device determines whether the position of the work vehicle is inside or outside the field based on the position determined by the positioning system and the environmental map.

[0166] [Item 6]

[0167] The work vehicle according to item 5, wherein:

[0168] The positioning system comprises:

[0169] an external sensor that outputs sensor data indicating a distribution of land objects existing around the work vehicle; and

[0170] The self-position estimating device estimates the position of the work vehicle by matching the sensor data with the environment map.

[0171] [Item 7]

[0172] The work vehicle according to any one of items 1 to 6, wherein

[0173] The control device performs automatic travel control of the work vehicle based on the estimated position of the work vehicle.

[0174] [Item 8]

[0175] The work vehicle according to item 7, wherein:

[0176] When the travel stop command is issued during the automatic travel control, the control device stops the motor at different timings depending on whether the work vehicle is located in a field.

[0177] [Item 9]

[0178] The work vehicle according to any one of items 1 to 8, wherein

[0179] The work vehicle is an agricultural machine.

[0180] Industrial applicability

[0181] The technology disclosed herein can be applied to agricultural machinery such as tractors, harvesters, rice transplanters, ride-on maintenance machines, vegetable transplanters, lawn mowers, seed drills, fertilizer spreaders, or agricultural robots.

[0182] Description of reference numerals:

[0183] 1 User interface, 2 Operation device, 3 Main ECU, 4 Main instrument, 5 FC system ECU, 6 FC instrument, 7 Storage device, 8 Positioning system, 8 AGNSS receiver, 8B External sensor, 8C Self-position estimation device, 10 Fuel cell module, 11 FC stack, 40 Boost circuit, 34 Radiator device, 40 Boost circuit, 50 Fuel tank, 51 Tank body, 70 Motor, 71 Output shaft, 72 Inverter device, 72A Control device, 74 Power transmission system, 76 Power take-off (PTO) shaft, 80 Battery pack, 81 First DC-DC converter, 82 Second DC-DC converter, 83 Storage battery, 85 Refrigeration compressor, 86 Heater, 100 Work vehicle, 102 Vehicle body, 102A Front frame, 102B Transmission case, 104 Wheels, 104F Front wheels, 104R Rear wheels, 107 Driver's seat, 120 Fixed frame

Claims

1. A working vehicle, have: A fuel cell module having a fuel cell stack; a motor connected to the fuel cell module; a traveling device, driven by the motor; A control device for controlling the motor; as well as Positioning system, where The control device changes the manner in which the motor is stopped when a travel stop instruction is issued during driving of the motor, depending on whether the position of the work vehicle determined by the positioning system is within a field. The control device makes the time from issuance of the travel stop command to stop the motor shorter when the work vehicle is located in a field than the time from issuance of the travel stop command to stop the motor when the work vehicle is located outside the field.

2. The work vehicle according to claim 1, wherein: The working vehicle further includes a first switch provided on a current path between the fuel cell module and the motor. The control device responds to a travel stop instruction issued during the driving of the motor, determining whether the position of the work vehicle determined by the positioning system is inside the field or outside the field, When the working vehicle is located in a field, the motor is stopped by turning off the first switch. When the working vehicle is located outside a field, after receiving the travel stop instruction, the motor is stopped after the motor is driven for a predetermined period of time.

3. The work vehicle according to claim 2, wherein: The working vehicle also has: a battery connected to the fuel cell module and the motor; and a second switch, disposed on a current path between the battery and the motor, When the work vehicle is located in a field, the control device turns off the first switch and the second switch in response to the travel stop instruction to stop the motor.

4. The work vehicle according to claim 1, wherein: The positioning system includes a GNSS receiver.

5. The working vehicle according to any one of claims 1 to 4, wherein: The work vehicle further includes a storage device storing an environmental map of an area including one or more fields. The control device determines whether the position of the work vehicle is inside or outside the field based on the position determined by the positioning system and the environmental map.

6. The work vehicle according to claim 5, wherein: The positioning system comprises: an external sensor that outputs sensor data indicating distribution of ground objects existing around the work vehicle; and The self-position estimating device estimates the position of the work vehicle by matching the sensor data with the environment map.

7. The work vehicle according to claim 1, wherein: The control device performs automatic travel control of the work vehicle based on the estimated position of the work vehicle.

8. The work vehicle according to claim 7, wherein: When the travel stop command is issued during the automatic travel control, the control device stops the motor at different timings depending on whether the position of the work vehicle is in a field.

9. The working vehicle according to any one of claims 1, 2, 3, 4, 7 and 8, wherein: The working vehicle is an agricultural machine.

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