Work vehicle, electric fan control method, and computer program

Abstract

This electric work vehicle comprises: one or more pieces of electric equipment; a battery that stores electric power to be supplied to the one or more piece of electric equipment; a cooling system that includes an electric fan and is configured to cool the battery and / or the one or more pieces of electric equipment; and a control device that controls the electric fan. The control device is configured or programmed to wait after the work vehicle is started until a command for starting the electric fan is transmitted, and is configured or programmed to start the electric fan in response to the command when the command is transmitted.

Description

Work vehicle, method for controlling an electric fan, and computer program

[0001] The present disclosure relates to a work vehicle, a method for controlling an electric fan, and a computer program.

[0002] In the field of automobiles whose main purpose is to move people or objects, electric vehicles (EVs) that generate driving force (traction) for driving by an electric motor (hereinafter sometimes simply referred to as a "motor") instead of an internal combustion engine are becoming more popular.

[0003] On the other hand, in order to realize a decarbonized society, it is required to reduce the amount of carbon dioxide (CO ２ ) emitted by work vehicles such as tractors used in fields. Different from general automobiles, work vehicles such as tractors need to tow a work implement (agricultural implement) to perform agricultural work such as tilling. Therefore, in order to realize the electrification of work vehicles, there are problems to be solved different from the electrification of passenger cars.

[0004] Patent Document 1 discloses an electric tractor that distributes and supplies electric power from a battery to a plurality of electric motors. The electric tractor includes a hydraulic pump, a pump motor, a PTO motor, a traveling motor, a battery, and an electric drive controller. The pump motor is an electric motor that drives the hydraulic pump. The PTO motor is an electric motor that drives the PTO shaft. The traveling motor is an electric motor that drives to make the traveling body travel. The battery supplies electric power to the pump motor, the PTO motor, and the traveling motor. The electric drive controller controls the distribution of electric power to the pump motor, the PTO motor, and the traveling motor.

[0005] Japanese Patent Application Laid-Open No. 2023-66721

[0006] In a conventional work vehicle equipped with an internal combustion engine, consumption of fossil fuel and emission of greenhouse gases are inevitable. On the other hand, in an electric work vehicle, various problems to be solved such as ensuring safety, improving running performance, improving quietness, reducing environmental load, improving convenience, or reducing costs remain.

[0007] This disclosure provides an electric work vehicle capable of solving at least one of these problems.

[0008] This disclosure provides solutions as described in the following items.

[0009] [Item 1] An electric work vehicle comprising: one or more electric devices; a battery for storing power to supply power to the one or more electric devices; a cooling system including an electric fan and configured to cool the battery and at least one of the one or more electric devices; and a control device for controlling the electric fan, wherein the control device is configured or programmed to wait after the work vehicle has been started until a command to start the electric fan is transmitted, and when the command is transmitted, to start the electric fan in response to the command.

[0010] [Item 2] The work vehicle according to Item 1, comprising a running gear, wherein the one or more electric devices include a first electric motor that drives the running gear, and the cooling system is configured to cool the battery and the first electric motor.

[0011] [Item 3] The work vehicle according to Item 2, comprising: a PTO shaft for supplying power to a work machine; a second electric motor for generating power to be transmitted to the PTO shaft; and a power transmission system including a clutch for transmitting power from the second electric motor to the PTO shaft, wherein the one or more electric devices include the second electric motor, and the cooling system is configured to cool the battery, the first electric motor, and the second electric motor.

[0012] [Item 4] The work vehicle according to any one of items 1 to 3, wherein the cooling system includes at least one radiator through which a cooling medium, cooled by the cooling air generated by the electric fan, flows.

[0013] [Item 5] The work vehicle according to Item 3, wherein the cooling system includes a first cooling system configured to cool the battery, comprising a first radiator through which a first cooling medium cooled by the cooling air generated by the electric fan flows, and a second cooling system configured to cool the first electric motor and the second electric motor, comprising a second radiator through which a second cooling medium cooled by the cooling air generated by the electric fan flows.

[0014] [Item 6] The work vehicle according to Item 3, wherein when the clutch is engaged, power is transmitted from the second electric motor to the PTO shaft; when the clutch is disengaged, the transmission of power from the second electric motor to the PTO shaft is interrupted; and the control device starts the electric fan in response to the command transmitted when the clutch state switches from the disengaged state to the engaged state.

[0015] [Item 7] The work vehicle according to Item 2, wherein the control device starts the electric fan in response to a command transmitted when the rotational speed of the first electric motor exceeds a speed threshold.

[0016] [Item 8] A work vehicle according to any one of items 1 to 5, comprising a charging inlet, wherein the control device starts the electric fan in response to a command transmitted when a charging adapter is connected to the charging inlet.

[0017] [Item 9] A work vehicle according to any one of items 1 to 8, comprising a temperature sensor for measuring the temperature of the battery, wherein the control device starts the electric fan in response to a command transmitted when the temperature of the battery indicated by the sensor data output from the temperature sensor exceeds a first temperature threshold.

[0018] [Item 10] The work vehicle according to any one of items 1 to 9, wherein the control device rotates the electric fan in a first rotational direction in response to the command, and rotates the electric fan periodically or periodically for a predetermined time in a second rotational direction opposite to the first rotational direction while the electric fan is rotating in the first rotational direction.

[0019] [Item 11] A work vehicle according to any one of items 1 to 8, comprising a temperature sensor for measuring the temperature of the battery and at least one of the one or more electric devices, wherein the control device compares the temperature indicated by the sensor data output from the temperature sensor with the ambient temperature, and stops the electric fan if the ambient temperature exceeds the temperature.

[0020] [Item 12] The work vehicle according to Item 11, wherein the control device, when the ambient temperature falls below the temperature, causes the electric fan to continue rotating when the temperature is equal to or greater than the second temperature threshold, and stops the electric fan when the temperature is less than the second temperature threshold.

[0021] [Item 13] The work vehicle according to Item 12, wherein the control device changes the rotation speed of the electric fan based on the temperature when the ambient temperature is below the temperature and the temperature is above the second temperature threshold.

[0022] [Item 14] The work vehicle according to any one of items 11 to 13, wherein the temperature sensor measures the temperature of the battery.

[0023] [Item 15] The control device includes one or more processors and one or more memories that store a program for controlling the operation of the one or more processors, wherein the one or more processors wait in accordance with the program after the work vehicle is started until a command to start the electric fan is transmitted, and when the command is transmitted, they start the electric fan in response to the command, the work vehicle according to Item 1.

[0024] [Item 16] A control method implemented in a computer that controls an electric fan included in a cooling system mounted on an electric work vehicle, which comprises one or more electric devices and a battery for storing power supplied to the one or more electric devices, wherein the cooling system includes the electric fan and is configured to cool the battery and at least one of the one or more electric devices, and the control method includes: waiting after the work vehicle has started up until a command to start the electric fan is transmitted; and starting the electric fan in response to the command when the command is transmitted.

[0025] [Item 17] A computer program used to control an electric fan included in a cooling system mounted on an electric work vehicle comprising one or more electric devices and a battery for storing power supplied to the one or more electric devices, wherein the cooling system includes the electric fan and is configured to cool the battery and at least one of the one or more electric devices, and the computer program causes the computer to perform the following actions: wait after the work vehicle has started until a command to start the electric fan is transmitted; and when the command is transmitted, start the electric fan in response to the command.

[0026] [Item 18] A control device configured to perform the method described in Item 16.

[0027] [Item 19] A computer-readable non-temporary storage medium that stores a computer program containing instructions for causing a computer to perform the method described in Item 16.

[0028] [Item 20] A cooling system comprising the control device described in Item 18 and one or more cooling fans.

[0029] [Item 21] A control device for controlling an electric fan mounted on an electric work vehicle, wherein the work vehicle comprises: one or more electric devices; a battery for storing power to supply to the one or more electric devices; and a cooling system including the electric fan and configured to cool the battery and at least one of the one or more electric devices, wherein the control device is configured or programmed to wait after the work vehicle has started until a command to start the electric fan is transmitted, and when the command is transmitted, to start the electric fan in response to the command.

[0030] [Item 22] A vehicle system comprising the control device described in Item 21 and a cooling system including an electric fan.

[0031] Comprehensive or specific embodiments of the present invention may be realized by apparatus, systems, methods, integrated circuits, computer programs, or computer-readable non-temporary storage media, or any combination thereof. The computer-readable storage media may include volatile storage media or non-volatile storage media. The apparatus may consist of multiple devices. If the apparatus consists of two or more devices, these two or more devices may be located in a single device or in two or more separate devices.

[0032] According to embodiments of this disclosure, a work vehicle capable of improving noise reduction is provided.

[0033] This is a schematic plan view showing an example of the basic configuration of a work vehicle according to an exemplary embodiment of the present invention. This is a side view of a work vehicle according to an exemplary embodiment of the present invention. This is a top view of a work vehicle according to an exemplary embodiment of the present invention. This is a block diagram showing an example of the main components of a work vehicle and their connection relationships. This is a block diagram showing an example of the configuration of a power converter and its connection to other equipment. This is a block diagram showing an example of the hardware configuration of each ECU. This is a block diagram showing an example of the configuration of a power distribution unit. This is a block diagram showing the schematic configuration of a cooling system in an exemplary embodiment of the present invention. This is a block diagram showing the configuration of a cooling system including a first and second cooling system in an exemplary embodiment of the present invention. This is a flowchart showing the procedure for controlling a cooling fan in an exemplary embodiment of the present invention. This is a diagram showing an example of the configuration of a power transmission system for work. This is a block diagram showing the configuration of a cooling system including a temperature sensor in an exemplary embodiment of the present invention. This is a flowchart showing the procedure for controlling a cooling fan according to a first implementation example in an exemplary embodiment of the present invention. This is a flowchart showing the procedure for controlling a cooling fan according to a second implementation example in an exemplary embodiment of the present invention. This is a block diagram showing an example of the configuration of an air-cooled cooling system in an exemplary embodiment of the invention.

[0034] Embodiments of the present invention will be described below. However, unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid the following description becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The inventors provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present invention, and not to limit the subject matter described in the claims. In the following description, components having the same or similar function are denoted by the same reference numerals.

[0035] The following embodiments are illustrative examples for realizing the technical concept of the present invention, and the present invention is not limited to these embodiments. For example, the numerical values, shapes, materials, steps, and order of steps shown in the following embodiments are merely examples, and various modifications are possible as long as they do not create a technical inconsistency. Furthermore, it is possible to combine one embodiment with other embodiments. The size and positional relationships of the components shown in each drawing may be exaggerated for ease of understanding.

[0036] (Definition of Terms) In this specification, “work vehicle” means a vehicle used for a specific task, such as agricultural work or construction work. “Work” may be, for example, agricultural work, construction work, rubble removal work, or snow removal work. Agricultural work vehicles may be, for example, tractors, combine harvesters, rice transplanters, riding cultivators, vegetable transplanters, vegetable harvesters, mowers, seeders, fertilizer spreaders, sprayers, or broadcasters. Construction work vehicles may be, for example, backhoes, wheel loaders, or carriers. An agricultural work vehicle such as a tractor or combine harvester, or a construction work vehicle, may function as a “work vehicle” on its own, or the work vehicle and any implements attached to or towed by it may function as a single “work vehicle.” Agricultural work vehicles perform agricultural tasks on the ground within a field (or work area), such as tilling, sowing, pest control, fertilizing, planting crops, or harvesting. Construction vehicles perform tasks such as transporting soil, rubble, and other materials at construction sites. These tasks are sometimes referred to as "ground work" or simply "work." When a construction vehicle moves while performing work, it is sometimes referred to as "work driving."

[0037] An "electric work vehicle" refers to a work vehicle that runs using an electric motor as its power source. An electric work vehicle may also be equipped with an internal combustion engine as an auxiliary power source in addition to the electric motor. Alternatively, an electric work vehicle may be equipped with an electric motor as an auxiliary power source in addition to the internal combustion engine. An electric work vehicle is equipped with an electrical energy source, such as a battery or fuel cell, to supply power to the electric motor. In the following description, an "electric work vehicle" may be simply referred to as a "work vehicle."

[0038] Electric motors can be synchronous motors such as permanent magnet synchronous motors or reluctance motors, or asynchronous motors such as induction motors.

[0039] A battery is an energy storage device that stores the electrical energy necessary for the operation of electric motors and other electrical components mounted on a work vehicle and / or work machine. A fuel cell is a power generation device that generates such electrical energy from a fuel such as hydrogen. An electrical energy source can be realized by an energy storage device, a power generation device, or a combination of an energy storage device and a power generation device. Furthermore, an electric work vehicle may obtain electrical energy from an electrical energy source located at a distance from the vehicle (e.g., on the ground or on another vehicle) via wired or wireless means.

[0040] When an electric work vehicle performs various "tasks" while moving or stationary, the power required for those tasks may be obtained from electric motors. An electric work vehicle is equipped with one or more electric motors. If an electric work vehicle is equipped with multiple electric motors, certain electric motors may output the driving force required for movement, while other electric motors may output the driving force required for the "tasks." If some or all of the "tasks" are performed by a work machine, the driving force can be mechanically transmitted from one or more electric motors on the electric work vehicle to the work machine. Such mechanical transmission of driving force can be achieved via a power transmission shaft called a power take-off (PTO) shaft.

[0041] The work machine itself may be equipped with an electric motor for the work. In this case, power may be supplied to the electric motor of the work machine from an electrical energy source such as a battery or fuel cell equipped in the electric work vehicle. The work machine may also be equipped with an electrical energy source that stores the power required for the work.

[0042] A "control device" (controller) is a device that controls the operation of part or all of a work vehicle. One example of a "control device" is a computing device comprising at least one processor and at least one memory that stores a computer program (code) that defines the control process executed by the processor. Another example of a "control device" is a computing device with a hardware accelerator such as an FPGA (Field-Programmable Gate Array), ASSP (Application Specific Standard Product), or ASIC (Application-Specific Integrated Circuit) configured or programmed to execute the control process. A control device may also be a collection of multiple devices. For example, several computing devices such as physically separated electronic control units (ECUs) may work together to function as a "control device".

[0043] A "processor" is a hardware electronic circuit such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), ISP (Image Signal Processor), or NPU (Neural Network Processing Unit).

[0044] "Memory" is a hardware electronic circuit such as ROM (Read Only Memory) or RAM (Random Access Memory). A part of the memory may be a storage medium connected to the processor via wiring or a network. These hardware electronic circuits can be implemented by one or more integrated circuits (ICs) or large-scale integrated circuits (LSIs). Each functional unit or block within the electronic circuit, and related components, may be manufactured individually as separate integrated circuit chips, or some or all of these functional units or blocks may be combined and manufactured as a single integrated circuit chip. A computer program (hereinafter sometimes simply referred to as "program") that defines the operation of the processor may be stored in the memory. The program is designed so that the processor executes one or more functions, operations, steps, or processes in the embodiments of the present invention.

[0045] (Embodiment) Hereinafter, several embodiments in which the technology of the present invention is applied to an agricultural electric tractor, which is an example of an electric work vehicle, will be described while referring to the drawings. Various technologies described for the tractor in the following description can also be applied to agricultural machines other than tractors, construction work vehicles used at construction sites, work vehicles used at disaster sites, snow removal vehicles used in heavy snow areas, and vehicles for transporting goods.

[0046] In the following description, the direction of arrow F in the figure is referred to as "front", the direction of arrow B as "rear", the direction of arrow L as "left", the direction of arrow R as "right", the direction of arrow U as "up", and the direction of arrow D as "down".

[0047] <1. Basic Configuration of Work Vehicle> FIG. 1 is a plan view schematically showing an example of the basic configuration of a work vehicle 10 according to an exemplary embodiment of the present invention. The illustrated work vehicle 10 is an agricultural electric tractor. The work vehicle 10 can travel in a field while mounting or towing a work implement and performing farm work according to the type of the work implement. The work vehicle 10 can also travel in the field and outside the field (including roads) with the work implement lifted or without mounting the work implement.

[0048] The work vehicle 10 is equipped with a body (vehicle frame) 11 that rotatably supports the left and right front wheels 14F and the left and right rear wheels 14R. The body 11 includes a front frame 12 on which the front wheels 14F are mounted and a transmission case 13 on which the rear wheels 14R are mounted. The front frame 12 is fixed to the front of the transmission case 13. The front wheels 14F and the rear wheels 14R may be collectively referred to as "wheels 14". Strictly speaking, wheels 14 are wheels, and tires are mounted on the wheels 14. In this disclosure, "wheels" generally means the entire "wheel and tire". One or both of the front wheels 14F and the rear wheels 14R may be replaced with a plurality of wheels (crawlers) equipped with a track instead of wheels with tires.

[0049] The work vehicle 10 in the example shown in Figure 1 is equipped with a battery 20 and an electric motor 30 (hereinafter simply referred to as "motor 30") which are directly or indirectly supported by the front frame 12. The battery 20 may be configured as a battery pack including, for example, multiple cells connected in series. The battery 20 is a rechargeable battery that outputs a relatively high voltage, such as a lithium-ion battery or an all-solid-state battery. The battery 20 stores power to drive the motor 30. The battery 20 may be housed in a front housing, for example, called a "bonnet." The front housing is supported by the front frame 12 located at the front of the vehicle body 11.

[0050] The motor 30 is electrically connected to the battery 20. The motor 30 can convert the power output from the battery 20 into mechanical motion (power) to generate the driving force (traction) necessary for the work vehicle 10 to move. The motor 30 may be, for example, an AC synchronous motor. The battery 20 generates DC current. For this reason, if the motor 30 is an AC synchronous motor, a group of electrical circuits including an inverter device (hereinafter sometimes simply referred to as "inverter") may be provided between the battery 20 and the motor 30. The inverter device converts the DC current into AC current. Part of such a group of electrical circuits may be located inside the battery 20. Another part of the group of electrical circuits may be attached to the motor 30 as a drive circuit for the motor 30.

[0051] The motor 30 has a rotating output shaft 33. The torque of the output shaft 33 is transmitted to the rear wheels 14R via mechanical components such as a transmission (speed changer) and a rear wheel differential (differential gear device) located inside the transmission case 13. In other words, the power generated by the motor 30, which is the power source, is transmitted to the rear wheels 14R by a power transmission system (drivetrain) 34, including a transmission, located inside the transmission case 13. For this reason, the "transmission case" is sometimes called a "transmission case". In four-wheel drive mode, a portion of the power from the motor 30 is also transmitted to the front wheels 14F. In this way, the motor 30 drives a running gear including multiple wheels 14.

[0052] The power of the motor 30 may be used not only for the movement of the work vehicle 10 but also for driving the work implement. A PTO shaft 40 is provided at the rear end of the transmission case 13. A work implement can be connected to the PTO shaft 40. The PTO shaft 40 may be driven by the motor 30 that drives the travel device, or by another electric motor not shown in Figure 1. Torque from the output shaft 33 of the motor 30 or the output shaft of another motor is transmitted to the PTO shaft 40. The work implement attached to or towed by the work vehicle 10 receives power from the PTO shaft 40 and can perform operations according to various tasks. The motor 30 and the power transmission system 34 are sometimes collectively referred to as the electric powertrain.

[0053] As shown in Figure 1, the work vehicle 10 does not have an internal combustion engine such as a diesel engine, but is equipped with a battery 20 and a motor 30. The output shaft 33 of the motor 30 is mechanically coupled to a power transmission system 34, such as a transmission, in a transmission case 13. The motor 30 can efficiently generate torque over a relatively wide range of rotational speeds compared to an internal combustion engine. By using the power transmission system 34, including the transmission, it becomes easy to adjust the torque and rotational speed from the motor 30 over an even wider range by performing multi-stage or continuously variable speed changes. Therefore, it is possible to efficiently perform not only the movement of the work vehicle 10 but also a variety of tasks using work equipment.

[0054] Depending on the intended use or size of the work vehicle 10, some functions of the power transmission system 34 may be omitted. For example, some or all of the transmission responsible for the gear shifting function may be omitted. The number and mounting positions of the motors 30 are not limited to the example shown in Figure 1. Furthermore, the work vehicle may be a hybrid electric vehicle (HEV) equipped with an internal combustion engine such as a diesel engine as a power source in addition to electric motors.

[0055] The work vehicle 10 shown in Figure 1 is equipped with one motor 30. However, the work vehicle 10 may be equipped with multiple electric motors. For example, the work vehicle 10 may be equipped with a drive electric motor that drives a running gear including four wheels 14, and a PTO electric motor that drives the PTO shaft 40. The work vehicle 10 may be equipped with multiple PTO shafts (e.g., a rear PTO shaft, a mid PTO shaft, a front PTO shaft, etc.). In that case, one electric motor may drive multiple PTO shafts, or multiple electric motors may drive multiple PTO shafts. For example, the work vehicle 10 may be equipped with multiple electric motors, each driving a corresponding one of the multiple PTO shafts. The work vehicle 10 may be equipped with a front wheel electric motor that drives two front wheels 14F, and a rear wheel electric motor that drives two rear wheels 14R. Alternatively, the work vehicle 10 may be equipped with two electric motors for the front wheels, each driving one of the two front wheels 14F, and two electric motors for the rear wheels, each driving one of the two rear wheels 14R. In other words, the work vehicle 10 may be equipped with four electric motors, each driving one of the four wheels 14. Thus, the work vehicle 10 may be equipped with one or more electric motors for driving the running gear and one or more electric motors for driving one or more PTO shafts. By providing multiple electric motors, the work vehicle 10 can control the rotation of multiple wheels 14 and one or more PTO shafts more flexibly. In the following description, electric motors for driving may be referred to as "driving motors," and electric motors for PTOs may be referred to as "PTO motors."

[0056] <2. Specific Examples of Work Vehicles> Next, we will explain a more specific example of the configuration of work vehicle 10.

[0057] Figure 2 is a side view of a work vehicle 10 according to an exemplary embodiment of the present invention. Figure 3 is a top view of the work vehicle 10 according to this embodiment.

[0058] The work vehicle 10 shown in Figures 2 and 3 comprises a vehicle body 11 and a running gear supported by the vehicle body 11. The running gear includes various devices necessary for driving, such as left and right front wheels 14F, left and right rear wheels 14R, front axle 15F, rear axle 15R, and a rear wheel differential.

[0059] The vehicle body 11 comprises a front frame 12, a transmission case 13, and a housing frame 16. The front frame 12 is connected to the front of the housing frame 16. The transmission case 13 is connected to the rear of the housing frame 16. A first electric motor 30A and a second electric motor 30B are housed inside the housing frame 16. The first electric motor 30A is a driving motor and drives the running gear via a power transmission system in the transmission case 13. The second electric motor 30B is a PTO motor and drives the PTO shaft 40 and one or more hydraulic pumps. The first electric motor 30A and the second electric motor 30B may be electric motors capable of relatively high efficiency and high torque output, such as permanent magnet synchronous motors.

[0060] The front frame 12 is fitted with a front axle case 17F. The front axle case 17F supports the left and right front wheels 14F. The transmission case 13 includes a rear axle case 17R. The rear axle case 17R supports the left and right rear wheels 14R and transmits power to the rear wheels 14R.

[0061] A battery 20 is mounted on the front frame 12. The battery 20 is supported by the front frame 12 and housed inside the front housing 19 (bonnet). The battery 20 stores the power supplied to the first electric motor 30A and the second electric motor 30B. In other words, the battery 20 stores power for driving, operation, and hydraulic drive. In the following description, the battery 20 may be referred to as the "drive battery 20".

[0062] Above the housing frame 16 and the transmission case 13 are a steering wheel 53, a meter panel unit 54, a group of pedals 55 including the accelerator and brake, a group of switches 56 for work driving, and a driver's seat 52. A safety frame 51 is provided behind the driver's seat 52. The safety frame 51 is attached to the transmission case 13 and has a structure that extends upward. Inside the housing frame 16 are the first electric motor 30A and the second electric motor 30B.

[0063] The switch group 56 includes various operating devices such as switches, levers, and dials for adjusting the operation of the work vehicle 10 and the work implement. The switch group 56 includes various operating devices such as an accelerator lever for adjusting the travel speed, a switch for switching the PTO shaft 40 on and off, a dial for adjusting the rotational speed of the PTO shaft 40, and a lever for adjusting the height of the three-point linkage supporting the work implement. By operating the switch group 56, the driver can give various instructions to the work vehicle 10 for travel and work.

[0064] The meter panel unit 54 displays information regarding the status of the work vehicle 10. For example, the meter panel unit 54 displays various information such as the travel speed, the rotational speed of the PTO shaft 40, the height of the three-point linkage, the output of the motors 30A and 30B, the charge status of the battery 20, and the temperature of the battery 20. The meter panel unit 54 may be equipped with analog meters and / or a digital display (hereinafter sometimes simply referred to as "display") for displaying this information. The display of the meter panel unit 54 may display a graphical user interface (GUI) that allows the user to perform various setting operations related to the work vehicle 10. The user can perform various settings related to the work vehicle 10 on the display screen using an input device connected to the meter panel unit 54 or an input means such as a touchscreen mounted on the display.

[0065] As shown in Figure 3, a charging inlet 57 is provided to the right of the steering wheel 53. The charging inlet 57 is a device that includes a socket configured to allow connection of a charging adapter extending from an external power source or charger. Near the charging inlet 57, a device for the user to initiate charging, such as a charging start button, may be provided. When the user connects the charging adapter to the charging inlet 57 and performs a predetermined operation, such as pressing the charging start button, charging of the battery 20 begins.

[0066] The battery 20 can be charged using either normal charging or rapid charging. In normal charging, AC power supplied from an external AC power source is converted to high-voltage DC power (e.g., around 350V to 450V), and this DC power is supplied to the battery 20. In rapid charging, high-voltage DC power is directly supplied to the battery 20 from an external DC power source. The charging inlet 57 in this embodiment supports both normal and rapid charging. For normal charging, a commercial AC power source that outputs an AC voltage of, for example, 200V or 100V may be used as the power source. For rapid charging, a DC power source that outputs a DC voltage of, for example, around 350V to 450V may be used as the power source. Rapid charging can be performed using protocols compliant with standards such as CHAdeMO, NACS, CCS1, CCS2, GB / T, or ChaoJi.

[0067] The power stored in the battery 20 can also be output to external electrical equipment via the charging inlet 57. Such external power output is referred to as "external power supply" in this specification. External power supply is performed with an external power supply adapter connected to the charging inlet 57. The DC power from the battery 20 can be converted to AC power by a power converter in the work vehicle 10. This AC power can then be supplied to external equipment via the charging inlet 57 and the external power supply adapter.

[0068] As shown in Figure 3, the first electric motor 30A and the second electric motor 30B in this embodiment are arranged side by side. The first electric motor 30A and the second electric motor 30B are rotated by power supplied from the battery 20. The first electric motor 30A drives the running gear via a power transmission system in the transmission case 13. The second electric motor 30B drives the PTO shaft 40 and the hydraulic pump via a power transmission system in the transmission case 13. As a result, the second electric motor 30B drives the work implement and various hydraulic devices. The hydraulic devices may be used, for example, to change the height of the three-point linkage supporting the work implement. The work vehicle 10 may be equipped with a power steering system that assists the driver's steering wheel operation. In this case, the hydraulic devices may also be used in the power steering system to supply auxiliary force to change the steering angle of the front wheels 104F.

[0069] <3. System Configuration of the Work Vehicle> Figure 4 is a block diagram showing the main components of the work vehicle 10 and an example of their connection relationships. In Figure 4, connection relationships related to power transmission, high-voltage drive power, and low-voltage auxiliary power are represented by solid lines of different thicknesses. Connection relationships related to signals (digital signals and analog signals) are represented by dotted lines. Coolant flow is represented by thick dashed lines.

[0070] As shown in Figure 4, the work vehicle 10 is equipped with a first inverter 35A and a second inverter 35B. The first inverter 35A is connected to the first electric motor 30A. The second inverter 35B is connected to the second electric motor 30B. Each of the first inverter 35A and the second inverter 35B converts the DC voltage from the battery 20 into a three-phase AC voltage. The first inverter 35A supplies the converted three-phase AC voltage to the first electric motor 30A. This causes the first electric motor 30A to rotate and the traction device to be driven. The second inverter 35B also supplies the converted three-phase AC voltage to the second electric motor 30B. This causes the second electric motor 30B to rotate and the hydraulic pump 36 and the PTO shaft 40 to be driven.

[0071] The transmission case 13 houses the power transmission system 34A for driving, the power transmission system 34B for work, and the hydraulic pump 36. The power transmission system 34A for driving may include components such as a reduction gear, a sub-transmission, and a differential. The power transmission system 34A for driving transmits power from the rotation of the first electric motor 30A to the rear wheels 14R. In four-wheel drive mode, the power transmission system 34A for driving also transmits a portion of the power from the rotation of the first electric motor 30A to the front wheels 14F. The power transmission system 34B for work may include components such as a reduction gear, a PTO clutch, and a PTO transmission. The power transmission system 34B for work transmits power from the rotation of the second electric motor 30B to the hydraulic pump 36 and the PTO shaft 40. The PTO shaft 40 supplies power for work to the work implement.

[0072] The PTO shaft 40 shown in Figure 4 is the rear PTO shaft. In addition to the rear PTO shaft, the work vehicle 10 may also have a mid-PTO shaft or a front PTO shaft. If the work vehicle 10 has multiple PTO shafts, the power transmission system 34B may be configured to distribute the power generated by the rotation of the second electric motor 30B to the multiple PTO shafts. Alternatively, in addition to the second electric motor 30B that drives the PTO shaft 40, the work vehicle 10 may include other electric motors that drive the other PTO shafts.

[0073] The implements connected to the PTO shaft 40 may include, for example, a rotary tiller, a seeder, a spreader, a transplanter, a mower, a rake, a baler, a harvester, a sprayer, or a harrow. Any implement can be connected to the work vehicle 10 and used.

[0074] The hydraulic pump 36 is driven by power from the second electric motor 30B. The hydraulic pump 36 pressurizes the hydraulic fluid, thereby changing the height of the three-point linkage to which the work equipment is connected. Alternatively, the hydraulic pump 36 may be used in a hydraulic power steering system. If a front loader is mounted as the work equipment, the hydraulic pump 36 may be used in a hydraulic system that enables the lifting and lowering of the front loader. Power from the second electric motor 30B may be transmitted to multiple hydraulic pumps to drive these multiple hydraulic systems. Alternatively, the work vehicle 10 may have one or more electric motors for hydraulics separate from the second electric motor 30B.

[0075] In the example shown in Figure 4, the work vehicle 10 further comprises a power converter 58, a power distribution unit (PDU) 80, an auxiliary battery 21, and a battery temperature control system 70.

[0076] The power converter 58 is positioned between the charging inlet 57 and the battery 20 and performs power conversions such as AC to DC conversion and voltage conversion. Figure 5 shows an example of the configuration of the power converter 58 and its connection to other equipment. The power converter 58 shown in Figure 5 includes an onboard charger (OBC) 81 and a DC-DC converter 82. During normal charging, the OBC 81 converts AC power from the charging inlet 57 to DC power and supplies it to the drive battery 20 via the power distribution unit 80. The drive battery 20 is charged by this DC power. The DC-DC converter 82 is connected to the OBC 81 and also to the battery 20 via the power distribution unit 80. The DC-DC converter 82 converts the relatively high-voltage DC power output from the OBC 81 or the drive battery 20 to lower-voltage DC power (e.g., 12V or 24V). The low-voltage DC power converted by the DC-DC converter 82 is supplied to the auxiliary battery 21 and the auxiliary components 84. The auxiliary components 84 include several devices that operate on the relatively low voltage output from the DC-DC converter 82 or the battery 21. For example, the auxiliary components 84 include several electronic control units (ECUs) and other electrical components. The auxiliary battery 21 is charged by the DC voltage output from the DC-DC converter 82. The auxiliary battery 21 stores the power supplied to the auxiliary components 84, such as each ECU, the meter panel unit 54, the pumps 67, 77, and the air conditioner. The battery 21 may be, for example, a lead-acid battery.

[0077] Refer to Figure 4 again. The work vehicle 10 is equipped with multiple ECUs. The multiple ECUs include a main ECU 61, an electric ECU 62, and a charging ECU 63. The main ECU 61 controls the overall operation of the work vehicle 10 based on signals generated by the user operating the pedal group 55, the switch group 56, and the meter panel unit 54. The electric ECU 62 mainly controls the charging and discharging of the battery 20 and the operation of the electric motors 30A and 30B. The charging ECU 63 communicates with an external charger (external power supply) and performs control to ensure smooth charging by appropriately controlling the relay 64.

[0078] In this embodiment, the combination of the main ECU 61, the electric ECU 62, and the charging ECU 63 functions as a "control device" that controls the operation of the work vehicle 10. Therefore, in the following description, the operations performed by the main ECU 61, the electric ECU 62, and the charging ECU 63 all correspond to operations performed by the "control device". These ECUs can communicate with each other according to a vehicle bus standard such as CAN (Controller Area Network). Instead of CAN, a faster communication method such as on-board Ethernet (registered trademark) may be used. An on-board computer integrating at least some of the functions of the main ECU 61, the electric ECU 62, and the charging ECU 63 may be provided as the "control device". The control device may include ECUs other than the main ECU 61, the electric ECU 62, and the charging ECU 63. Each ECU may be a computing device including one or more processors and one or more memories. Each ECU can perform the operations described later by having the processor execute a computer program stored in the memory.

[0079] The electric ECU 62 sends control signals to the first inverter 35A and the second inverter 35B in response to signals from the pedal group 55 and the switch group 56. The electric ECU 62 can perform motor control based on a rotational speed command value or a torque command value determined, for example, according to the amount of operation of the pedal group 55 by the driver.

[0080] The electric ECU 62 controls the switching operation of multiple switch elements (e.g., MOSFETs) in the first inverter 35A and the second inverter 35B, respectively. Specifically, the electric ECU 62 generates control signals to control the switching operation of each switch element and outputs them to each inverter. The first inverter 35A converts the DC power from the battery 20 into three-phase AC power, which is a pseudo-sine wave of, for example, u-phase, v-phase, and w-phase, according to the control signals from the electric ECU 62, and supplies this three-phase AC power to the first electric motor 30A. Similarly, the second inverter 35B converts the DC power from the battery 20 into three-phase AC power, which is a pseudo-sine wave of, for example, u-phase, v-phase, and w-phase, according to the control signals from the electric ECU 62, and supplies this three-phase AC power to the second electric motor 30B. As a result, the electric ECU 62 can rotate the electric motors 30A and 30B at appropriate rotational speeds and torques according to the driver's operation.

[0081] While the work vehicle 10 is in operation, the main ECU 61 causes the meter panel unit 54 to display information regarding the status of the work vehicle 10. For example, the main ECU 61 displays information such as the travel speed, the operating status of the motors 30A and 30B, the charge status of the battery 20, and the status of the power transmission system 34A and the transmission included in 34A on the meter panel unit 54.

[0082] Figure 6 is a block diagram showing an example of the hardware configuration of each ECU. Each ECU 400 includes a processor 434, ROM 435, RAM 436, external I / F 437, and communication I / F 438. These components are interconnected via a bus 439.

[0083] ROM 435 is, for example, writable memory (e.g., PROM), rewritable memory (e.g., flash memory), or read-only memory. ROM 435 stores a program that controls the operation of the processor 434. ROM 435 does not have to be a single recording medium; it may be a collection of multiple recording media. Some of the multiple storage media may be removable memory.

[0084] RAM 436 provides a working area for temporarily unpacking the program stored in ROM 435 at boot time. RAM 436 does not need to be a single recording medium; it may be a collection of multiple recording media.

[0085] External I / F 437 is an interface for connecting to external devices. Communication I / F 438 is an interface for communicating with other electronic devices (e.g., sensors and other ECUs). For example, communication I / F 438 can perform wired communication compliant with various protocols such as CAN or Ethernet®. Communication I / F 438 may also perform wireless communication compliant with wireless communication standards such as Bluetooth® and / or Wi-Fi®.

[0086] The ECU may further include a storage device for storing data generated by the processor 434 for a relatively long period of time. Such a storage device may be, for example, a semiconductor storage device, a magnetic storage device, or an optical storage device, or a combination thereof.

[0087] The power distribution unit 80 shown in Figure 4 is a device that electrically connects equipment such as the charging inlet 57, power converter 58, battery 20, inverters 35A and 35B, and heater 72.

[0088] Figure 7 shows an example of the configuration of the power distribution unit 80. The power distribution unit 80 may have a plurality of relay circuits 83 (83a to 83g) that operate under the control of the electric ECU 62. During charging, the power distribution unit 80 is configured to supply power from the charging inlet 57 or the power converter 58 to the battery 20, and to the heater 72 when the temperature is low. On the other hand, during discharging, the power distribution unit 80 is configured to distribute power from the battery 20 to the first inverter 35A, the second inverter 35B, and the power converter 23. The electric ECU 62 may be configured or programmed to control the charging and discharging of the battery 20 by appropriately switching the on and off of the plurality of relay circuits 83a to 83g in the power distribution unit 80. In this specification, relay circuits may be simply referred to as "relays".

[0089] As shown in Figure 4, the battery 20 includes a battery management system (BMS) 22 and a temperature sensor 24. The BMS 22 is configured to monitor the state of the battery 20, such as the input voltage, output voltage, and temperature, and to control the charging and discharging currents to the battery 20 based on these states. The temperature sensor 24 may be configured to measure the temperature of each of the multiple cells contained in the battery 20.

[0090] The work vehicle 10 illustrated in Figure 4 is equipped with a cooling system 60 for high-voltage equipment and a battery temperature control system 70. The cooling system 60 is used to cool equipment to which high voltage is applied (also referred to as "high-voltage equipment"). The cooling system 60 comprises a radiator 65, a reservoir tank 66, a pump 67, and a cooling fan 68. In the example in Figure 4, the cooling system 60 is connected via hoses to the first inverter 35A, the first electric motor 30A, the second electric motor 30B, the second inverter 35B, and the power converter 58 in that order. This forms a flow path through which the coolant circulates. The coolant in the cooling system 60 is, for example, water or oil. The cooling system 60 cools these high-voltage equipment by circulating the coolant through the flow path. The coolant heated by the high-voltage equipment is cooled by heat dissipation in the radiator 65. The cooling fan 68 generates cooling air to cool the coolant inside the radiator 65. The cooling air promotes heat dissipation from the radiator 65.

[0091] The battery temperature control system 70 is used to cool or heat (also referred to as "heating") the battery 20. The battery temperature control system 70 comprises a heater 72, a radiator 75, a reservoir tank 76, and a pump 77. The battery temperature control system 70 is connected to the battery 20 via a hose. This creates a passage through which the coolant circulates. The coolant in the battery temperature control system 70 is, for example, water or oil. The battery temperature control system 70 cools the battery 20 by circulating the coolant through the passage. The coolant heated by the battery 20 is cooled by heat dissipation in the radiator 75. Cooling air from the cooling fan 68 also plays a role in cooling the coolant inside the radiator 75. The heater 72 raises the temperature of the battery 20 by warming the coolant. This makes it possible to suppress a decrease in the charge and discharge performance of the battery 20 even in low-temperature environments where the ambient temperature is, for example, below 0 degrees Celsius (°C).

[0092] The operation of the cooling system 60 and the battery temperature control system 70 is controlled by the electric ECU 62. For example, the electric ECU 62 is configured or programmed to maintain the temperature of the battery 20 within an appropriate range by controlling the battery temperature control system 70 based on the temperature of the battery 20 measured by the temperature sensor 24. In addition to the measurement value of the temperature sensor 24, the electric ECU 62 may also control the battery temperature control system 70 based on the measurement value of a temperature sensor 25 that measures the ambient temperature and is installed in the work vehicle 10.

[0093] The flow paths of the coolant in the cooling system 60 and the battery temperature control system 70 are not limited to the illustrated paths and can be changed as appropriate. The cooling method in the cooling system 60 and the battery temperature control system 70 is not limited to water cooling or oil cooling, but may also be air cooling. Alternatively, the refrigerant used in an air conditioner may be used instead of the above-mentioned coolant.

[0094] <4. Control of Cooling Fans> As mentioned above, the work vehicle is equipped with one or more cooling systems. Each cooling system may include a radiator through which coolant flows, which is cooled by the cooling air generated by a cooling fan, and may be configured to cool one or more electric devices, including a battery.

[0095] Traditionally, whenever a work vehicle was started—in other words, whenever the power switch or ignition was turned on—the cooling fan would activate every time. Compared to work vehicles equipped with internal combustion engines, work vehicles equipped with electric motors are generally easier to operate quietly. However, the noise from the cooling fan, which operates in sync with the start of the work vehicle every time, compromises the quietness of the work vehicle. For this reason, improvement in the quietness of work vehicles is desirable.

[0096] To solve the above problems, the electric work vehicle in this embodiment comprises one or more electric devices, a battery for storing power to supply to the one or more electric devices, a cooling system including an electric fan and configured to cool the battery and at least one of the one or more electric devices, and a control device for controlling the electric fan. The cooling method of the cooling system may be liquid cooling or air cooling. In the following description, the electric fan will be referred to as the "cooling fan".

[0097] One or more electric devices may include various electric devices such as a traction motor, a PTO motor, an inverter, a BMS, a heater, and an ECU. In this embodiment, the cooling targets of the cooling system are these electric devices and the battery.

[0098] The cooling fan is controlled by a control device. The control device is configured or programmed to wait after the work vehicle is started until a command to start the cooling fan is transmitted, and then start the cooling fan in response to the command. For example, the electric ECU 62 shown in Figure 4 may function as the control device for controlling the cooling fan. Of course, one or more other ECUs different from the electric ECU 62 may function as the control device, or the electric ECU 62 and one or more other ECUs may cooperate to perform the functions of the control device.

[0099] The control device in this embodiment may include one or more processors and one or more memories that store programs for controlling the operation of the one or more processors. The one or more processors may, according to the program, wait after the work vehicle has started up until a command to start the cooling fan is transmitted, and when the command is transmitted, they may start the cooling fan in response to the command.

[0100] The control method implemented in a computer that controls a cooling fan included in a cooling system mounted on an electric work vehicle, which comprises one or more electric devices and a battery for storing power supplied to the one or more electric devices, includes waiting after the work vehicle has started up until a command to start the cooling fan is transmitted, and starting the cooling fan in response to the command once the command has been transmitted.

[0101] A computer program containing instructions for causing one or more computers to execute the above-described method for controlling a cooling fan may be manufactured and sold independently of the work vehicle. The computer program may be provided, for example, stored on a computer-readable non-temporary storage medium. The computer program may also be provided by download via a telecommunications line (e.g., the Internet).

[0102] According to the control method for the work vehicle, cooling fan, and computer program of this embodiment, it is possible to improve quietness by not starting the cooling fan after the work vehicle has started until a command to start the cooling fan is sent.

[0103] The cooling system in this embodiment may include at least one radiator through which a cooling medium, cooled by cooling air generated by a cooling fan, flows.

[0104] Figure 8 is a block diagram showing the schematic configuration of the cooling system in this embodiment.

[0105] The cooling system 100 shown in Figure 8 includes a radiator 110 through which a cooling medium flows, a pump 120 that circulates the cooling medium flowing through the flow path 150 back to the radiator 110, a reservoir tank (hereinafter simply referred to as "tank") 130, and a cooling fan 160 that generates cooling air to cool the cooling medium. The cooling medium in the cooling system 100 is a coolant.

[0106] Radiator 110 corresponds to radiator 65 or 75 shown in Figure 4. Pump 120 corresponds to pump 67 or 77 shown in Figure 4. Tank 130 corresponds to tank 66 or 76 shown in Figure 4. Cooling fan 160 corresponds to cooling fan 68 shown in Figure 4.

[0107] The flow path 150 connects the radiator 110 and the object to be cooled 140. For example, the flow path 150 connects the radiator 110 to the battery and at least one of one or more electric devices. In the example in Figure 8, the cooling system 100 is connected to the radiator 110, tank 130, pump 120 and object to be cooled 140 in this order. This forms a flow path 150 through which the cooling medium circulates.

[0108] The pump 120 illustrated in Figure 8 is a variable displacement pump-motor and a hydraulic pump capable of flowing a cooling medium in one direction. However, the pump 120 is not limited to a variable displacement pump-motor and may be a fixed displacement pump. Furthermore, the pump 120 is not limited to a hydraulic pump.

[0109] In this embodiment, the cooling fan 160 is powered, for example, by an auxiliary battery 21 shown in Figure 5. When the DC-DC converter 82 is started, power is supplied from the DC-DC converter 82 to the auxiliary battery 21 (i.e., charging begins).

[0110] In one embodiment, the cooling system 100 may be configured to cool the battery and the drive motor.

[0111] In another embodiment, the cooling system 100 may be configured to cool the battery, the drive motor, and the PTO motor.

[0112] The cooling system in this embodiment may include a first cooling system and a second cooling system.

[0113] Figure 9 is a block diagram showing the configuration of the cooling system, including the first and second cooling systems, in this embodiment.

[0114] The cooling system 101 shown in Figure 9 includes a first cooling system 101A and a second cooling system 101B. The first cooling system 101A includes a first radiator 110A through which a first cooling medium, cooled by a cooling fan 160, flows, and is configured to cool the battery 20. The first cooling system 101A includes a first radiator 110A, a first flow path 150A connecting the first radiator 110A and the battery 20, and a first pump 120A that circulates the first cooling medium flowing through the first flow path 150A to the first radiator 110A.

[0115] The second cooling system 101B includes a second radiator 110B through which a second cooling medium, cooled by the cooling air generated by a cooling fan 160, flows, and is configured to cool a drive motor 30A, which is an example of a first electric motor, and a PTO motor 30B, which is an example of a second electric motor. The second cooling system 101B includes a second radiator 110B, a second flow path 150B connecting the second radiator 110B, the drive motor 30A, and the PTO motor 30B, and a second pump 120B that circulates the second cooling medium flowing through the second flow path 150B to the second radiator 110B.

[0116] The first cooling system 101A and the second cooling system 101B correspond to the battery temperature control system 70 and the high-voltage equipment cooling system 60 shown in Figure 4, respectively. The first cooling medium and the second cooling medium may be the same or different.

[0117] The first pump 120A and the second pump 120B shown in Figure 9 are variable displacement pump motors and hydraulic pumps that enable the flow of a cooling medium in one direction. However, the first pump 120A and the second pump 120B are not limited to variable displacement pump motors, but may be fixed displacement pumps, for example. Also, the first pump 120A and the second pump 120B are not limited to hydraulic pumps.

[0118] The cooling system 101 illustrated in Figure 9 includes a common cooling fan 160 that generates cooling air to cool a first cooling medium flowing inside the first radiator 110A and a second cooling medium flowing inside the second radiator 110B. However, separate cooling fans may be provided for the first radiator 110A and the second radiator 110B, respectively.

[0119] The battery and motor are electric devices that require special cooling as a measure against heat dissipation. The first cooling system 101A is a system specifically for cooling the battery 20, and the second cooling system 101B is a system specifically for cooling the drive motor 30A and the PTO motor 30B. By providing separate cooling systems in this way, it is possible to increase the cooling capacity of each cooling system.

[0120] Figure 10 is a flowchart showing the procedure for controlling the cooling fan in this embodiment.

[0121] The power switch or ignition is turned on by the user, which starts the work vehicle (step S101). Since the cooling fan consumes a large current, it is preferable to start it after the DC-DC converter (see Figure 5) has started and the auxiliary battery is ready to charge. In this embodiment, the control device may wait after the work vehicle has started until the DC-DC converter has started.

[0122] The control device, for example, after confirming that the DC-DC converter has started, waits until a start command is sent to start the cooling fan (NO in step S102).

[0123] A start command can be transmitted in sync with various events. For example, a start command may be transmitted when the rotational speed of the drive motor exceeds a speed threshold. This control improves the quietness of the work vehicle's startup because the cooling fan starts when the vehicle speed exceeds a predetermined value. The speed threshold can be appropriately determined according to the specifications of the motor or work vehicle.

[0124] A start command may be transmitted when the charging adapter is connected to the charging inlet (see Figure 4). This is useful, for example, when a work vehicle is performing stationary work while being charged with the charging adapter connected to the charging inlet.

[0125] Figure 11 shows an example of a power transmission system configuration for work.

[0126] In the example shown in Figure 11, the power transmission system 34B for operation includes a reduction gear 37B, a PTO clutch 38B, and a PTO transmission 39B. The PTO clutch 38B is positioned between the reduction gear 37B and the PTO transmission 39B and connects them. Through this mechanical connection, when the PTO clutch 38B is engaged, power is transmitted from the PTO motor 30B to the PTO shaft 40, and when the PTO clutch 38B is disengaged, the transmission of power from the PTO motor 30B to the PTO shaft 40 is interrupted. In other words, when the PTO clutch 38B is engaged, power is transmitted from the reduction gear 37B to the PTO transmission 39B. On the other hand, when the clutch is disengaged, the transmission of power from the reduction gear 37B to the PTO transmission 39B is interrupted.

[0127] A start command may be transmitted when the state of the PTO clutch 38B switches from the disengaged state to the engaged state. In other words, a start command may be transmitted when the PTO clutch 38B is turned on.

[0128] Figure 12 is a block diagram showing the configuration of a cooling system including a temperature sensor in this embodiment. The object to be cooled by the cooling system 102 shown in Figure 12 is a battery 20. The cooling system 102 further includes a temperature sensor 170 for measuring the temperature of the battery 20.

[0129] The temperature sensor 170 may be configured to measure the temperature of the battery 20 and output sensor data indicating the temperature of the battery 20 to the control device 400. For example, the temperature sensor 170 may be configured to measure the temperature of the cooling medium flowing out from the flow path outlet side of the battery 20. The temperature sensor 170 can estimate the temperature of the battery 20 from the measured temperature of the cooling medium.

[0130] A start command may be transmitted when the temperature of the battery 20, as indicated by the sensor data output from the temperature sensor 170, exceeds a temperature threshold. This temperature threshold may be appropriately determined according to the specifications of the battery or the work vehicle.

[0131] Refer to Figure 10 again. In this way, start commands can be transmitted in synchronization with various events. When a start command is transmitted, the control device is configured or programmed to start the cooling fan in response to the start command (step S103).

[0132] As described above, according to this embodiment, the cooling fan remains stopped after the work vehicle is started until a start command is transmitted. For example, the cooling fan is started only after the PTO clutch is turned on or the rotational speed of the drive motor reaches a predetermined value or higher. This suppresses the noise of the cooling fan, which was operating in sync with the start of the work vehicle, and as a result, it is possible to ensure the quietness of the work vehicle.

[0133] Figure 13 is a flowchart showing the procedure for controlling the cooling fan according to the first implementation example in this embodiment.

[0134] The control device rotates the cooling fan in a first rotational direction (e.g., forward rotation) in response to a start command. After starting the cooling fan in response to the start command (step S103), the control device may periodically or periodically rotate the cooling fan in a second rotational direction opposite to the first rotational direction for a predetermined time (e.g., reverse rotation) while the cooling fan is rotating in the first rotational direction. For example, the control device reverses the cooling fan for 10 seconds every 10 minutes. However, the timing of the reverse rotation of the cooling fan can be arbitrarily set by the user. The number of times the reverse rotation is performed may be only once at the beginning, and can be arbitrarily set.

[0135] During operation, the radiator may become clogged with debris such as grass straw. In this case, clogging can be suppressed by periodically or periodically reversing the rotation of the cooling fan for a predetermined period of time.

[0136] The work vehicle may be equipped with a temperature sensor that measures the temperature of the battery and at least one of one or more electric devices. In this embodiment, the work vehicle is equipped with a temperature sensor that measures the temperature of the battery, as illustrated in Figure 12. In other words, the temperature sensor measures the temperature of the battery.

[0137] Figure 14 is a flowchart showing the procedure for controlling the cooling fan according to the second implementation example in this embodiment.

[0138] After the control device starts the cooling fan in response to the start command (step S103), it obtains the battery temperature (step S105). For example, the control device receives sensor data indicating the battery temperature output from a temperature sensor. The control device obtains the battery temperature from this sensor data.

[0139] The control device further acquires the ambient temperature. For example, the control device receives sensor data indicating the ambient temperature, which is output from a temperature sensor that measures the ambient temperature. The control device then acquires the ambient temperature from this sensor data.

[0140] The control device compares the battery temperature with the ambient temperature (step S106).

[0141] The control device stops the cooling fan (step S108) if the ambient temperature exceeds the battery temperature (YES in step S106). If the cooling fan operates and draws in heat when the ambient temperature is higher than the battery temperature, the cooling effect of the cooling system may be significantly reduced. For example, if a work vehicle is moved from a relatively cool garage to an outdoor area with a high ambient temperature, operating the cooling fan may result in heating the battery rather than cooling it. In contrast, by stopping the cooling fan when the ambient temperature is higher than the battery temperature, i.e., not operating it, the reduction in cooling effect can be suppressed.

[0142] If the ambient temperature is lower than the battery temperature (NO in step S106), the control device compares the battery temperature with a temperature threshold (step S107). The temperature threshold may be appropriately determined according to the specifications of the battery or work vehicle. If the battery temperature is above the temperature threshold (YES in step S107), the control device may allow the cooling fan to continue rotating (step S110). On the other hand, if the battery temperature is below the temperature threshold (NO in step S107), the control device may stop the cooling fan (step S109).

[0143] In this way, by introducing a temperature threshold and adaptively controlling the operation of the cooling fan based on the battery temperature, it becomes possible to improve the cooling efficiency of the cooling system while reducing the power consumption of the cooling fan.

[0144] The control device may change the rotation speed of the cooling fan based on the battery temperature when the ambient temperature is below the battery temperature (NO in step S106) and the battery temperature is above the temperature threshold (YES in step S107). In other words, the control device may change the rotation speed of the cooling fan according to the magnitude of the difference between the battery temperature and the temperature threshold (the margin of the battery temperature relative to the temperature threshold). The larger the difference, the more the control device can increase the rotation speed of the cooling fan to enhance the cooling effect.

[0145] Figure 15 is a block diagram showing an example configuration of an air-cooled cooling system.

[0146] As mentioned above, the cooling method of the cooling system in this embodiment is not limited to liquid cooling but may be air cooling. The cooling system 103 illustrated in Figure 15 includes a cooling fan 160A for air cooling the battery 20, a cooling fan 160B for cooling the drive motor 30A, and a cooling fan 160C for cooling the PTO motor 30B. An air-cooled cooling system may further include a flow path for circulating a gas (refrigerant).

[0147] The control device 400 in the cooling system 103 may be configured or programmed to start the three cooling fans 160A, 160B, and 160C in response to a start command after the work vehicle has been started. The starting order of the three cooling fans 160A, 160B, and 160C is not particularly limited. For example, the control device 400 may start cooling fan 160A first in response to a start command after the work vehicle has been started, and then start cooling fans 160B and 160C. Alternatively, the cooling fan that cools the object being cooled by the cooling fan that has the highest current temperature or is prone to becoming hot may be started first among the three cooling fans 160A, 160B, and 160C.

[0148] With this type of control, all cooling fans remain stopped after the work vehicle is started until a start command is transmitted. This suppresses the noise from the cooling fans that were operating in sync with the start of the work vehicle, and as a result, ensures quiet operation of the work vehicle.

[0149] This invention is applicable to electric work vehicles in general.

[0150] 10...Work vehicle, 11...Body, 12...Front frame, 13...Transmission case, 14...Wheels, 14F...Front wheels, 14R...Rear wheels, 15F...Front axle, 15R...Rear axle, 16...Housing frame, 17F...Front axle case, 17R...Rear axle case, 19...Front housing, 20...Battery, 22...Battery management system (BMS), 24...Temperature sensor, 30, 30A, 30B, 30C...Electric motor, 33...Output shaft, 34...Power transmission system, 35, 35A, 35B...Inverter, 36...Hydraulic pump, 40...PTO shaft, 51...Rops frame, 52...Driver's seat, 53...Steering wheel, 54...Meter panel unit, 55...Pedal group, 56...Switch group, 57...Charging inlet 58... Power converter, 60... Cooling system for high-voltage equipment, 61... Main ECU, 62... Electric ECU, 63... Charging ECU, 64... Relay, 65... Radiator for high-voltage equipment, 66... ​​Reservoir tank, 67... Pump, 68, 190... Cooling fan, 70... Battery temperature control system, 70A... First power system, 70B... Second power system, 72... Heater, 75... Battery radiator, 76... Reservoir tank, 77... Pump, 80... Power distribution unit, 81... Onboard charger (OBC), 82... DC-DC converter, 100-103... Cooling system, 110... Radiator, 120... Pump, 130... Reservoir tank, 140... Cooling target, 150... Flow path, 160... Cooling fan, 170... Temperature sensor, 400... Control device

Claims

1. An electric work vehicle comprising: one or more electric devices; a battery for storing power to supply power to the one or more electric devices; a cooling system including an electric fan and configured to cool the battery and at least one of the one or more electric devices; and a control device for controlling the electric fan, wherein the control device is configured or programmed to wait after the work vehicle has been started until a command to start the electric fan is transmitted, and when the command is transmitted, to start the electric fan in response to the command.

2. The work vehicle according to claim 1, comprising a running gear, wherein the one or more electric devices include a first electric motor for driving the running gear, and the cooling system is configured to cool the battery and the first electric motor.

3. The work vehicle according to claim 2, comprising: a PTO shaft for supplying power to a work machine; a second electric motor for generating power to be transmitted to the PTO shaft; and a power transmission system including a clutch for transmitting power from the second electric motor to the PTO shaft, wherein the one or more electric devices include the second electric motor, and the cooling system is configured to cool the battery, the first electric motor, and the second electric motor.

4. The work vehicle according to any one of claims 1 to 3, wherein the cooling system includes at least one radiator through which a cooling medium, cooled by the cooling air generated by the electric fan, flows.

5. The work vehicle according to claim 3, wherein the cooling system comprises: a first cooling system configured to cool the battery, comprising a first radiator through which a first cooling medium cooled by the cooling air generated by the electric fan flows; and a second cooling system configured to cool the first electric motor and the second electric motor, comprising a second radiator through which a second cooling medium cooled by the cooling air generated by the electric fan flows.

6. The work vehicle according to claim 3, wherein when the clutch is engaged, power is transmitted from the second electric motor to the PTO shaft; when the clutch is disengaged, the transmission of power from the second electric motor to the PTO shaft is interrupted; and the control device starts the electric fan in response to the command transmitted when the clutch state switches from the disengaged state to the engaged state.

7. The work vehicle according to claim 2, wherein the control device starts the electric fan in response to a command transmitted when the rotational speed of the first electric motor exceeds a speed threshold.

8. A work vehicle according to any one of claims 1 to 3, comprising a charging inlet, wherein the control device starts the electric fan in response to a command transmitted when a charging adapter is connected to the charging inlet.

9. A work vehicle according to any one of claims 1 to 3, comprising a temperature sensor for measuring the temperature of the battery, wherein the control device starts the electric fan in response to a command transmitted when the temperature of the battery indicated by the sensor data output from the temperature sensor exceeds a first temperature threshold.

10. The work vehicle according to any one of claims 1 to 3, wherein the control device rotates the electric fan in a first rotational direction in response to the command, and rotates the electric fan periodically or periodically for a predetermined time in a second rotational direction opposite to the first rotational direction while the electric fan is rotating in the first rotational direction.

11. A work vehicle according to any one of claims 1 to 3, comprising a temperature sensor for measuring the temperature of the battery and at least one of the one or more electric devices, wherein the control device compares the temperature indicated by the sensor data output from the temperature sensor with the ambient temperature, and stops the electric fan if the ambient temperature exceeds the temperature.

12. The work vehicle according to claim 11, wherein the control device, when the ambient temperature falls below the temperature, causes the electric fan to continue rotating when the temperature is equal to or greater than a second temperature threshold, and stops the electric fan when the temperature is less than the second temperature threshold.

13. The work vehicle according to claim 12, wherein the control device changes the rotation speed of the electric fan based on the temperature when the ambient temperature is below the temperature and the temperature is above the second temperature threshold.

14. The work vehicle according to claim 11, wherein the temperature sensor measures the temperature of the battery.

15. The control device includes one or more processors and one or more memories for storing a program that controls the operation of the one or more processors, wherein the one or more processors wait in accordance with the program after the work vehicle is started until a command to start the electric fan is transmitted, and when the command is transmitted, they start the electric fan in response to the command, as described in claim 1.

16. A control method implemented in a computer that controls an electric fan included in a cooling system mounted on an electric work vehicle, which comprises one or more electric devices and a battery for storing power supplied to the one or more electric devices, wherein the cooling system includes the electric fan and is configured to cool the battery and at least one of the one or more electric devices, and the control method includes: waiting after the work vehicle has started up until a command to start the electric fan is transmitted; and starting the electric fan in response to the command when the command is transmitted.

17. A computer program used to control an electric fan included in a cooling system mounted on an electric work vehicle comprising one or more electric devices and a battery for storing power supplied to the one or more electric devices, wherein the cooling system includes the electric fan and is configured to cool the battery and at least one of the one or more electric devices, and the computer program causes the computer to perform the following actions: wait after the work vehicle has started until a command to start the electric fan is transmitted; and when the command is transmitted, start the electric fan in response to the command.

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