Work vehicles

Abstract

To provide a technology capable of improving the user-friendliness of a work vehicle that has an automatic steering function.SOLUTION: An example work vehicle includes: a steering wheel; an automatic steering mechanism that enables the automatic steering of the steering wheel; and a heat supplying device provided so as to be able to supply heat to the automatic steering mechanism.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a work vehicle. [Background technology]

[0002] Conventionally, there is known a work vehicle having an automatic steering mechanism that automatically steers the vehicle body (see, for example, Patent Document 1). The automatic steering mechanism disclosed in Patent Document 1 includes a steering motor and a gear mechanism. The steering motor is a motor that can control the rotation direction, rotation speed, rotation angle, etc. based on the vehicle body position. The gear mechanism includes a gear that is provided on the steering shaft and rotates together with the steering shaft, and a gear that is provided on the rotating shaft of the steering motor and rotates together with the rotating shaft. When the rotating shaft of the steering motor rotates, the steering shaft automatically rotates via the gear mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7030540 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the gear case that houses the gear mechanism is filled with grease to lubricate the gears. In low-temperature environments, the viscosity of the grease increases, raising concerns that the steering force (motor torque) will increase and reduce operability. Furthermore, in consideration of the increase in motor torque in low-temperature environments, it is conceivable to disable the automatic steering function in low-temperature environments to protect the steering motor. However, this raises concerns that convenience will be reduced.

[0005] In view of the above, an object of the present invention is to provide a technique that can improve the convenience of a work vehicle having an automatic steering function. [Means for solving the problem]

[0006] An exemplary work vehicle of the present invention includes a steering wheel, an automatic steering mechanism that enables automatic steering of the steering wheel, and a heat supply device that is provided so as to be able to supply heat to the automatic steering mechanism. [Effects of the Invention]

[0007] According to the exemplary embodiment of the present invention, the convenience of a work vehicle having an automatic steering function can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] A side view showing the general configuration of a tractor [Figure 2] Block diagram showing the configuration related to the tractor's automatic steering function [Figure 3] FIG. 10 is a diagram illustrating an example of a method for setting a reference line. [Figure 4] A side view showing the automatic steering mechanism and its surroundings. [Figure 5] FIG. 1 is a perspective view showing a schematic configuration of a gear mechanism with a gear case removed; [Figure 6] A block diagram showing the general configuration of a control system of a tractor equipped with a heat supply device according to a first embodiment. [Figure 7] 1 is a flowchart showing an example of a control process executed by a control device in a tractor equipped with a heat supply device according to a first embodiment; [Figure 8] A block diagram showing the general configuration of a heat supply device according to a second embodiment. [Figure 9] A flowchart showing an example of a control process executed by a control device in a tractor equipped with a heat supply device of a second embodiment. [Figure 10] 1 is a flowchart illustrating a method for selectively using an electric heater and a fluid transport mechanism when a heat supply device includes both an electric heater and a fluid transport mechanism. [Figure 11] A block diagram for explaining a second modified example of a tractor equipped with a heat supply device. [Figure 12] A block diagram for explaining a third modified example of a tractor equipped with a heat supply device. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described with reference to the drawings. In this embodiment, a tractor will be used as an example of a work vehicle. However, the work vehicle may be any work vehicle other than a tractor, such as a harvester, a rice transplanter, a combine harvester, civil engineering or construction equipment, or a snowplow.

[0010] In addition, in this specification, directions are defined as follows. First, the direction in which a tractor serving as a work vehicle travels during work is defined as "forward," and the opposite direction is defined as "rearward." Furthermore, the right side of the tractor's traveling direction is defined as right, and the left side is defined as left. The direction perpendicular to the front-to-back and left-to-right directions of the tractor is defined as up-to-down. In this case, the direction of gravity is defined as down, and the opposite side is defined as up. Note that the above directions are simply names used for the purpose of explanation, and are not intended to limit the actual positional relationships or directions.

[0011] <1. Overview of the work vehicle> 1 is a side view showing a schematic configuration of a tractor 1 according to an embodiment of the present invention. As shown in FIG. 1, the tractor 1 includes a vehicle body 2, an engine 3, and a transmission case 4.

[0012] A pair of left and right front wheels 5 are arranged at the front of the vehicle body 2. A pair of left and right rear wheels 6 are arranged at the rear of the vehicle body 2. The vehicle body 2 can travel using the front wheels 5 and rear wheels 6. In other words, the tractor 1 of this embodiment is a wheel tractor. However, the tractor 1 is not limited to a wheel tractor and may be a crawler tractor or the like.

[0013] The engine 3 is disposed at the front of the vehicle body 2 and is covered by a hood 7. The engine 3 is the drive source of the tractor 1. Note that the drive source of the tractor 1 may be another drive source such as an electric motor instead of an engine.

[0014] The transmission case 4 is disposed behind the engine 3 and below the driver's section 8. A power transmission device (not shown) is disposed inside the transmission case 4. The rotational power of the engine 3 is transmitted to at least one of the front wheels 5 and the rear wheels 6 via the power transmission device inside the transmission case 4.

[0015] The driving section 8 is provided behind the engine 3 on the vehicle body 2. The driving section 8 is the part where the driver (operator) sits. The driving section 8 includes a driver's seat 9 and a front panel 10. The driver's seat 9 is where the driver sits. The front panel 10 is disposed in front of the driver's seat 9. A steering wheel 11 is provided on the front panel 10. In other words, the steering wheel 11 is disposed in front of the driver's seat 9. The front panel 10 also has a meter display section and the like that shows the speed of the tractor 1.

[0016] The steering 11 includes a steering wheel 12, a steering column 13, and a steering shaft 14 (see Figure 2, etc., described later). That is, the tractor 1 is equipped with the steering wheel 12, the steering column 13, and the steering shaft 14. The steering wheel 12 is operated by a driver sitting in the driver's seat 9. The steering column 13 covers the steering shaft 14. The steering shaft 14 supports the steering wheel 12. The steering wheel 12 and the steering shaft 14 are rotatably supported by a support portion (not shown) disposed within the steering column 13. The steering shaft 14 is columnar and extends obliquely in a vertical direction, with the top being more rearward than the bottom. The steering wheel 12 is disposed at the upper end of the steering shaft 14. By rotating the steering wheel 12, the direction of the front wheels 5 can be changed.

[0017] The driving section 8 is also provided with, for example, various operating levers 15 and pedals 16 that are operated by the driver. The various operating levers 15 may include, for example, a main shift lever, a sub shift lever, and an operation lever. The various pedals 16 may include, for example, an accelerator pedal, a brake pedal, and a clutch pedal.

[0018] In this embodiment, a rope frame 17 is provided behind the driver's seat 9. The rope frame 17 can protect the driver in the event of a rollover of the tractor 1. Note that the tractor 1 may not be a rope type in which the rope frame 17 is provided, but may be a cabin type in which the driver's seat 9 is covered with a cabin.

[0019] A work implement coupling section 18 configured with a three-point linkage or the like is provided at the rear of the vehicle body 2. A work implement can be attached to the work implement coupling section 18. The work implement may be, for example, a tiller, plow, fertilizer applicator, pesticide sprayer, harvester, or reaper. A lifting device (not shown) having a hydraulic device such as a lifting cylinder is also provided at the rear of the vehicle body 2. The lifting device raises and lowers the work implement coupling section 18, thereby raising and lowering the work implement. Power generated by the engine 3 can be transmitted to the work implement coupled by the work implement coupling section 18 via the transmission case 4 and a power take-off shaft (PTO shaft; not shown) located at the rear of the vehicle body 2.

[0020] In this embodiment, the tractor 1 has an automatic steering function that autonomously steers the tractor 1 along a predetermined route. That is, the tractor 1 is configured to be able to travel either by manual steering, in which the driver operates the steering wheel 12, or by automatic steering. Figure 2 is a block diagram showing the configuration related to the automatic steering function of the tractor 1 according to this embodiment. Note that the tractor 1 may be configured to autonomously control at least one of the vehicle speed and the work performed by the implement, in addition to steering.

[0021] As shown in FIG. 2, the tractor 1 is equipped with an automatic steering mechanism 20 that enables automatic steering of the steering wheel 12. The automatic steering mechanism 20 has a motor 201 and a gear mechanism 202. The gear mechanism 202 transmits the rotational power of the motor 201 to the steering shaft 14. The motor 201 is provided so that the rotation direction, rotation speed, rotation angle, etc. can be controlled. When the output shaft of the motor 201 rotates, the steering shaft 14 automatically rotates via the gear mechanism 202. In other words, the steering wheel 12 can be automatically rotated by driving the motor 201. The gear mechanism 202 will be described in detail later. In this embodiment, the motor 201 and the gear mechanism 202 are disposed inside the steering column 13.

[0022] As shown in FIG. 2, the tractor 1 also includes a control device 21. The control device 21 is, for example, a computer device including an arithmetic unit, an input / output unit, and a storage unit. The arithmetic unit is, for example, a processor or a microprocessor. The storage unit is a main storage device such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The storage unit may further include an auxiliary storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The storage unit stores various programs, data, and the like. The arithmetic unit reads out various programs from the storage unit and executes arithmetic processing in accordance with the programs.

[0023] It should be noted that there may be a single or multiple control devices 21. When there are multiple control devices 21, the multiple control devices may be configured to be able to communicate with each other.

[0024] The control device 21 performs control related to automatic steering. That is, the control device 21 functions as a controller for automatic steering. The control device 21 is electrically connected to the motor 201 and controls the motor 201. The motor 201 is driven by being supplied with power determined by the control device 21. As described above, the driving force of the motor 201 is transmitted to the steering shaft 14 via the gear mechanism 202, and therefore the steering wheel 12 can be controlled by controlling the motor 201. In other words, the direction of the front wheels 5 can be controlled by controlling the motor 201.

[0025] In this embodiment, the control device 21 is electrically connected to the position acquisition unit 22 and the inertial measurement unit 23.

[0026] The position acquisition unit 22 acquires the position of the tractor 1 as, for example, latitude and longitude information using a positioning signal received by the positioning antenna 24 from a positioning satellite. The position acquisition unit 22 outputs the position information of the tractor 1 to the control device 21. For example, the position acquisition unit 22 may receive a positioning signal from a reference station (not shown) using an appropriate method and then perform positioning using a known RTK-GNSS (Real Time Kinematic GNSS) method. Alternatively, for example, the position acquisition unit 22 may perform positioning using a DGNSS (Differential GNSS) method.

[0027] The inertial measurement unit 23 includes a three-axis angular velocity sensor and a three-directional acceleration sensor. The inertial measurement unit 23 outputs measured information to the control device 21. The provision of the inertial measurement unit 23 makes it possible to measure inertial information such as the yaw angle, pitch angle, and roll angle of the vehicle body 2.

[0028] The control device 21 performs processes for starting and ending automatic steering in response to commands from an operator (such as a driver) using an operation unit (not shown). The control device 21 also determines the position and orientation of the body 2 of the tractor 1 based on information obtained from, for example, the position acquisition unit 22 and the inertial measurement unit 23. The control device 21 also performs calculations related to automatic steering in accordance with the relationship between the determined position, etc. of the body 2 and a predetermined route for automatic driving, and controls the motor 201 described above. The control device 21 also performs the following calculations (calculation for feedback control) in accordance with operation information of the motor 201.

[0029] Here, an overview of the automatic steering performed by the tractor 1 of this embodiment will be described. When performing automatic steering, first, a reference line L is set. Fig. 3 is a diagram for explaining an example of a method for setting the reference line L. The method for setting the reference line L may be a method other than the method shown in Fig. 3.

[0030] When setting the reference line L, first, the tractor 1 is moved to an appropriate position in the field (point A in the figure), and point A is registered. Point A is registered by a registration command from the driver. The position of the vehicle body 2 obtained by the position acquisition unit 22 at the time the command to register point A is issued is registered as the position of point A.

[0031] Once point A is registered, the driver manually drives the tractor 1 in a straight line to a predetermined position (point B in the figure). Then, when the tractor 1 reaches the predetermined position, point B is registered. Point B is registered in response to a registration command from the driver. The position of the vehicle body 2 obtained by the position acquisition unit 22 at the time the command to register point B is issued is registered as the position of point B. Once points A and B are registered, a straight line passing through points A and B is set as the reference line L.

[0032] Once the reference line L is set, lines parallel to the reference line L are generated at predetermined intervals as automatic driving lines. During automatic steering, steering control of the traveling direction of the tractor 1 is performed so that the automatic driving line coincides with the position of the vehicle body 2 acquired by the position acquisition unit 22. Steering control of the traveling direction of the tractor 1 is performed by controlling the motor 201.

[0033] <2. Detailed example of automatic steering mechanism> 4 is a side view showing the automatic steering mechanism 20 provided in the tractor 1 according to this embodiment and a schematic configuration of the surrounding area. As shown in FIG. 4, the gear mechanism 202 included in the automatic steering mechanism 20 has a gear case 2021.

[0034] The gear case 2021 is supported by a support member (not shown) within the steering column 13. The gear case 2021 rotatably supports the steering shaft 14. In this embodiment, the gear case 2021 has an upper case 2021a and a lower case 2021b. The upper case 2021a and the lower case 2021b are stacked on top of each other and fixed using fasteners such as bolts and nuts. A plurality of gears 2022 (see FIG. 5 described later) of the gear mechanism 202 are arranged in an internal space formed by stacking the upper case 2021a and the lower case 2021b.

[0035] The motor 201 is fixed to the upper case 2021a, and most of the motor 201 is disposed outside the upper case 2021a. An output shaft 2011 of the motor 201 (see FIG. 5 described later) protrudes into the gear case 2021.

[0036] FIG. 5 is a perspective view showing a schematic configuration of the gear mechanism 202 with the gear case 2021 removed. Note that FIG. 5 also includes elements other than the gear mechanism 202. As shown in FIG. 5, a shaft bearing 2023 fixed to the gear case 2021 is disposed within the gear case 2021. The steering shaft 14 is rotatably supported by the gear case 2021 via the shaft bearing 2023. Also, as shown in FIG. 5, two rotating shafts 2024 and 2025 rotatably supported by bearings (not shown) fixedly disposed in the gear case 2021 are disposed within the gear case 2021.

[0037] 5, the gear mechanism 202 includes a plurality of gears 2022. The plurality of gears 2022 includes a first gear 2022a, a second gear 2022b, a third gear 2022c, a fourth gear 2022d, a fifth gear 2022e, and a sixth gear 2022f.

[0038] The first gear 2022a is attached to the output shaft 2011 of the motor 201 and rotates together with the output shaft 2011. The second gear 2022b is attached to the first rotating shaft 2024 and rotates together with the first rotating shaft 2024. The second gear 2022b meshes with the first gear 2022a. That is, when the first gear 2022a rotates, the second gear 2022b also rotates. The third gear 2022c is attached to the same first rotating shaft 2024 as the second gear 2022b and rotates together with the first rotating shaft 2024. That is, when the second gear 2022b rotates, the third gear 2022c also rotates.

[0039] The fourth gear 2022d is attached to the second rotating shaft 2025 and rotates together with the second rotating shaft 2025. The fourth gear 2022d meshes with the third gear 2022c. That is, when the third gear 2022c rotates, the fourth gear 2022d also rotates. The fifth gear 2022e is attached to the same second rotating shaft 2025 as the fourth gear 2022d and rotates together with the second rotating shaft 2025. That is, when the fourth gear 2022d rotates, the fifth gear 2022e also rotates. The sixth gear 2022f is attached to the steering shaft 14 and rotates together with the steering shaft 14. The sixth gear 2022f meshes with the fifth gear 2022e. That is, when the fifth gear 2022e rotates, the sixth gear 2022f also rotates. As can be seen from the above, when the motor 201 is driven and the output shaft 2011 rotates, the rotational force is transmitted to the steering shaft 14 via the multiple gears 2022, causing the steering shaft 14 to rotate.

[0040] <3. Heat supply device> The gear case 2021, which houses the multiple gears 2022, is filled with grease (not shown) for the purpose of lubricating the gears 2022. The viscosity of the grease is likely to increase in a low-temperature environment, and this increase in viscosity of the grease has an undesirable effect on manual steering and automatic steering of the steering wheel 12. In consideration of this point, the tractor 1 of this embodiment is provided with a heat supply device 30 that is capable of supplying heat to the automatic steering mechanism 20.

[0041] By providing the heat supply device 30, it is possible to apply heat to the grease contained in the gear case 2021 and warm it up even when the tractor 1 is used in a low-temperature environment. In other words, it is possible to prevent the viscosity of the grease in the gear case 2021 from increasing even in a low-temperature environment. As a result, it is possible to prevent the operability of the steering wheel 12 from decreasing even in a low-temperature environment. Furthermore, it is possible to use the automatic steering function while avoiding a situation in which an excessive load is placed on the motor 201, even in a low-temperature environment. According to the configuration of this embodiment, it is possible to improve the convenience of the tractor 1 having an automatic steering function.

[0042] It is preferable that at least a portion of the heat supply device is disposed on or near the gear mechanism 202. This makes it easier to supply heat to the gear mechanism 202. This also makes it possible to supply heat from close to the grease filled in the gear case 2021 that constitutes the gear mechanism 202. In other words, heat can be efficiently applied to the grease. However, the heat supply device 30 may also be disposed on or near the motor 201. This makes it possible to efficiently heat the motor 201. In other words, the heat supply device 30 may be configured to supply heat to the motor 201.

[0043] [3-1. First Example] FIG. 4 shows a heat supply device 30A of a first embodiment. In this example, the heat supply device 30A includes an electric heater 31 that is arranged in a member that constitutes the automatic steering mechanism 20. The electric heater 31 is, for example, flat. In this example, the electric heater 31 is arranged in the gear case 2021. Specifically, the electric heater 31 is arranged on the outer surface of the gear case 2021. The electric heater 31 is arranged on the lower surface of the lower case 2021b. However, the electric heater 31 may also be arranged inside the gear case 2021. The electric heater 31 may also be arranged on the outer surface of the upper case 2021a.

[0044] The electric heater 31 is preferably placed in a state where it can easily apply heat to the grease filled in the gear case 2021. The electric heater 31 is preferably attached in direct contact with the gear case 2021 or attached via a member with good thermal conductivity. The gear case 2021 is preferably made of a member with good thermal conductivity, such as metal.

[0045] In a preferred embodiment, the electric heater 31 is a self-regulating heater that operates to maintain a predetermined temperature range. A self-regulating heater, such as a PTC (Positive Temperature Coefficient) heater, generates heat and increases resistance when current is applied. When the resistance increases due to heat generation, the current flow decreases, causing the temperature of the heater itself to drop. When the temperature of the heater itself drops, the resistance decreases and the current flow increases. Thus, a self-regulating heater has a self-temperature control function to maintain a predetermined temperature range without requiring a special control device. The electric heater 31 configured as a self-regulating heater may be configured to operate to maintain a temperature range of, for example, 0°C to 20°C. The lower limit temperature of the predetermined temperature range (e.g., the aforementioned 0°C) may be the lower limit temperature of a temperature range in which the viscosity of the grease is not expected to adversely affect the operability of the steering wheel 12, and may be determined through experiments, for example. The upper limit temperature of the predetermined temperature range may be, for example, 5°C or more higher than the lower limit temperature.

[0046] For example, suppose the tractor 1 is placed in a low-temperature environment below 0°C. In this case, the temperature of the gear mechanism 202 and its surroundings is also usually below 0°C. That is, the temperature of the electric heater 31 itself disposed in the gear case 2021 is also below 0°C. For this reason, the electric heater 31 configured as a self-regulating heater generates heat. This heat is supplied to the gear case 2021, and the gear case 2021 is warmed. This makes it possible to warm the grease filled in the gear case 2021. When the temperature of the electric heater 31 itself reaches the upper limit of a predetermined temperature range (for example, 20°C), the current flowing through the electric heater 31 is reduced, and the electric heater 31 stops generating heat.

[0047] As can be seen from the above, in this example, when the temperature of the automatic steering mechanism 20 is below the first temperature, the electric heater 31 starts to supply heat. The automatic steering mechanism 20 is warmed by the heat supply from the electric heater 31. In detail, when the ambient temperature of the gear mechanism 202 is below the first temperature, the electric heater 31 starts to supply heat. The heat supply from the electric heater 31 warms the gear mechanism 202, making it possible to suppress an increase in the viscosity of the grease. Note that the first temperature is, for example, the lower limit temperature of a temperature range in which the viscosity of the grease is not expected to adversely affect the operability of the steering wheel 12.

[0048] Furthermore, the electric heater 31 stops supplying heat when the temperature of the automatic steering mechanism 20 reaches a second temperature higher than the first temperature after the start of heat supply. The difference between the first temperature and the second temperature is, for example, 5°C or more. This configuration can prevent the automatic steering mechanism 20 from being heated unnecessarily. This configuration can also keep power consumption low.

[0049] In a configuration in which the electric heater 31 is used to supply heat as in this example, it is preferable to increase the amount of power generated by the engine 3 in consideration of the use of the electric heater 31.

[0050] In this example, the temperature of the automatic steering mechanism 20 is an estimated temperature using the electric heater 31 configured as a self-regulating heater. In this way, the temperature of the automatic steering mechanism 20 may not only be a temperature obtained by directly measuring the temperatures of the components that make up the automatic steering mechanism 20, but also an estimated temperature using temperature information obtained from the periphery of the automatic steering mechanism 20.

[0051] Furthermore, the electric heater 31 included in the heat supply device 30A may be a heater other than a self-controlled heater. In this case, the electric heater 31 may be configured to be on / off controlled in response to information from a temperature sensor that directly or indirectly measures the temperature of the automatic steering mechanism 20.

[0052] In a configuration in which the temperature of the automatic steering mechanism 20 is directly measured to control the on / off of the electric heater 31, for example, the temperatures of the motor 201 and the gear mechanism 202 may be directly measured. In this configuration, for example, the electric heater 31 may be turned on when the temperature information obtained from the temperature sensor determines that the temperature of the automatic steering mechanism 20 is less than a first temperature (for example, 0°C), and the electric heater 31 may be turned off when the temperature information obtained from the temperature sensor determines that the temperature is equal to or greater than a second temperature (for example, 20°C).

[0053] Furthermore, in a configuration in which the temperature of the automatic steering mechanism 20 is indirectly measured to control the on / off of the electric heater 31, for example, the outside air temperature or the temperature inside the cabin of the automatic steering mechanism 20 may be measured. In this configuration, for example, the electric heater 31 may be turned on when temperature information obtained from a temperature sensor indicates that the temperature of the automatic steering mechanism 20 is estimated to be below a first temperature (for example, 0°C), and the electric heater 31 may be turned off after a predetermined time has elapsed. The predetermined time is, for example, a time that allows the grease filled in the gear case 2021 to be sufficiently warmed, and may be determined appropriately through experiments, etc. The predetermined time may be changed according to the estimated temperature of the automatic steering mechanism 20, and may be made longer as the temperature decreases.

[0054] Fig. 6 is a block diagram showing a schematic configuration of a control system of a tractor 1 equipped with a heat supply device 30A of the first embodiment. As shown in Fig. 6, a control device 21 is provided so as to be able to acquire operation information of an electric heater 31 included in the heat supply device 30A. The operation information may be, for example, electricity supply information, and more specifically, current value information.

[0055] The control device 21 performs various control processes depending on the state of the heat supply device 30A. For example, the various control processes may include processes related to whether or not the automatic steering function can be used. Furthermore, for example, the various control processes may include notification processes that notify the operating status of the heat supply device 30A and whether or not the automatic steering function can be used. The notification device 40 appropriately notifies the driver of the tractor 1, etc., of information that should be notified, depending on the notification processes in the control device 21. Notification using the notification device 40 is not essential.

[0056] The notification device 40 may be, for example, a display device that displays the notification content on a screen. The notification device 40 may also be, for example, an audio output device that announces the notification content. Alternatively, the notification device 40 may be a light-emitting device that notifies the notification content by emitting light, or a vibration generating device that notifies the notification content by vibration, etc. For example, the notification device 40 may be at least one of a configuration provided on the body 2 of the tractor 1 and a configuration provided on a mobile communication terminal (not shown) that can communicate with the tractor 1.

[0057] Fig. 7 is a flowchart showing an example of control processing executed by the control device 21 in the tractor 1 equipped with the heat supply device 30A of the first embodiment. The control processing shown in Fig. 7 is started, for example, when the engine 3 of the tractor 1 is started. When the engine 3 is started, the electric heater 31 configured as a self-regulating heater is automatically put into an operating state (power on).

[0058] In step S1, the control device 21 determines whether heat is being supplied by the heat supply device 30A. Whether heat is being supplied can be determined, for example, by obtaining the current value of the electric heater 31. If it is determined that heat is being supplied (Yes in step S1), the process proceeds to the next step S2. If it is determined that heat is not being supplied (No in step S1), the flow shown in FIG. 7 ends.

[0059] In step S2, the control device 21 determines to disable the automatic steering function. Once this determination is made, automatic steering will not be started even if the driver or other person issues a command to start automatic steering. Furthermore, automatic driving using the automatic steering function will not be started automatically. In other words, the automatic steering function is disabled while heat is being supplied by the heat supply device 30A. This prevents automatic steering from being performed when the viscosity of the grease is high. In other words, it prevents a large load from being applied to the motor 201. Once it is determined that the automatic steering function will be disabled, processing proceeds to the next step S3.

[0060] In step S3, the control device 21 controls the notification device 40 to perform notification processing to notify the driver or the like that the automatic steering function cannot be used. For example, the fact that the automatic steering function cannot be used is displayed on a screen. Also, for example, audio guidance is given to inform the driver that the automatic steering function cannot be used. Note that in addition to or instead of the fact that automatic steering is not available, it may be notified that the automatic steering mechanism 20 is being heated by the heat supply device 30A. Once the notification processing has been performed, the process proceeds to the next step S4.

[0061] In step S4, the control device 21 monitors the completion of heat supply by the heat supply device 30A. Whether or not the heat supply is complete can be determined, for example, by obtaining the current value of the electric heater 31. If it is determined that the heat supply is complete (Yes in step S4), the process proceeds to the next step S5. If it is determined that the heat supply is not complete (No in step S4), the monitoring in step S4 continues.

[0062] In step S5, the control device 21 determines that the automatic steering function is available. Once this determination is made, the driver or the like can start automatic steering. Also, automatic driving using the automatic steering function can be started automatically. Once it is determined that the automatic steering function is available, the process proceeds to the next step S6.

[0063] In step S6, the control device 21 controls the notification device 40 to perform notification processing to notify that the automatic steering function is available. For example, a message that the automatic steering function is available is displayed on a screen. Also, for example, a voice message that the automatic steering function is available is provided. Note that in addition to or instead of notifying that automatic steering is available, it may be notified that the process of heating the automatic steering mechanism 20 by the heat supply device 30A has been completed.

[0064] Completion of step S6 ends the processing shown in Fig. 7. After the processing shown in Fig. 7 ends, the processing from step S1 onwards shown in Fig. 7 may be repeated again.

[0065] [3-2. Second Example] Fig. 8 is a block diagram showing a schematic configuration of a heat supply device 30B of the second embodiment. In Fig. 8, thick black lines indicate paths along which fluids flow, and white arrows indicate the directions in which the fluids flow.

[0066] As shown in FIG. 8, the heat supply device 30B includes a fluid transport mechanism 32 that transports fluid to the automatic steering mechanism 20. The heat supply device 30B supplies heat to the automatic steering mechanism 20 by transporting a fluid using the fluid transport mechanism 32. In this example, the fluid transport mechanism 32 transports coolant to the automatic steering mechanism 20 using a coolant circulation mechanism 50 that circulates coolant that cools the engine 3. That is, in this example, the fluid transported by the fluid transport mechanism 32 is coolant for cooling the engine (hereinafter referred to as engine coolant). The engine coolant may be, for example, water. By using engine coolant, the heat supply device 30B can be configured using components already provided in the tractor 1, minimizing the need to add new parts.

[0067] In this example, the fluid transported by the fluid transport mechanism 32 is engine coolant, but this is merely an example. The fluid transported by the fluid transport mechanism 32 may be gas instead of liquid. The fluid transport mechanism 32 may be configured to extract exhaust gas from the engine 3 or warm air generated by an air conditioning system and transport the gas to supply heat to the automatic steering mechanism 20.

[0068] As shown in Fig. 8, the coolant circulation mechanism 50 circulates the engine coolant by driving a pump 51. The engine coolant heated by the engine 3 is cooled by a radiator 52 and sent back to the engine 3 to cool the engine 3. The coolant circulation mechanism 50 has a coolant temperature sensor 53 that measures the temperature of the engine coolant. The engine coolant, which is at a low temperature when the engine 3 is started, normally rises in temperature as time passes after the engine 3 is started.

[0069] The fluid transport mechanism 32 takes the engine coolant circulated by the coolant circulation mechanism 50 from the coolant circulation mechanism 50 and transports it to the automatic steering mechanism 20. The fluid transport mechanism 32 then returns the engine coolant that has been used as a heat source for the automatic steering mechanism 20 to the coolant circulation mechanism 50. In detail, the fluid transport mechanism 32 includes a jacket 321 and a valve 322.

[0070] The jacket 321 is provided so as to cover at least a portion of the components that make up the automatic steering mechanism 20. In this example, the jacket 321 is provided so as to cover at least a portion of the gear case 2021. The jacket 321 has a flow path therein through which the engine coolant flows. The valve 322 switches between a conveying state and a non-conveying state of the engine coolant using the fluid conveying mechanism 32. When the valve 322 is open, the conveying state is established, and when the valve 322 is closed, the non-conveying state is established. The valve 322 is composed of an electromagnetic valve or the like, and is provided so that its opening and closing can be controlled by the control device 21.

[0071] Fig. 9 is a flowchart showing an example of control processing executed by the control device 21 in the tractor 1 equipped with the heat supply device 30B of the second embodiment. The control processing shown in Fig. 9 is started, for example, when the engine 3 of the tractor 1 is started.

[0072] In step S11, the control device 21 determines whether the temperature input from the coolant temperature sensor 53 is below a predetermined temperature. The predetermined temperature may be, for example, the lower limit temperature of a temperature range in which the viscosity of the grease is not expected to adversely affect the operability of the steering wheel 12, and may be determined as appropriate through experiments, etc. The predetermined temperature may be, for example, 0°C. In this example, the temperature of the coolant temperature sensor 53 is used as an estimate of the temperature of the automatic steering mechanism 20. However, the temperature of the components constituting the automatic steering mechanism 20 or the temperature around them may be used instead of the temperature of the coolant temperature sensor 53. If the temperature of the coolant temperature sensor 53 is below the predetermined temperature (Yes in step S11), the process proceeds to the next step S12. If the temperature of the coolant temperature sensor 53 is equal to or higher than the predetermined temperature (No in step S11), the flow shown in FIG. 9 is ended.

[0073] In step S12, the control device 21 controls the valve 322 to open it. Opening the valve 322 causes the engine coolant to flow through the jacket 321. As a result, the engine coolant, which is gradually warmed by the start of the engine 3, starts to supply heat to the gear case 2021. That is, when the temperature of the automatic steering mechanism 20 is below a predetermined temperature, the fluid transport mechanism 32 starts transporting a fluid to supply heat. Note that in this example, the temperature of the automatic steering mechanism 20 is an estimated value, as described above. However, the temperature of the automatic steering mechanism 20 may also be an actual measurement value obtained by measuring the temperatures of the components that make up the automatic steering mechanism 20. Once the valve 322 is opened, the process proceeds to the next step, S13.

[0074] In step S13, the control device 21 determines to disable the automatic steering function. The processing in step S13 is similar to the processing in step S2 in Fig. 7 of the first embodiment, and therefore a detailed description thereof will be omitted. Once it is determined that the automatic steering function is disabled, the process proceeds to the next step, S14.

[0075] In step S14, the control device 21 controls the notification device 40 (see FIG. 6) to perform notification processing to notify the driver that the automatic steering function cannot be used. The processing in step S14 is similar to the processing in step S3 in FIG. 7 of the first embodiment, and therefore a detailed description thereof will be omitted. Once the notification processing is performed, the process proceeds to the next step S15.

[0076] In step S15, the control device 21 monitors the passage of a predetermined time. The predetermined time is, for example, the time required to sufficiently warm the grease filled in the gear case 2021 by supplying heat using the engine coolant, and may be appropriately determined through experiments, etc. The predetermined time may be changed, for example, according to the temperature obtained using the coolant temperature sensor 53, and may be set longer as the temperature decreases. If it is determined that the predetermined time has passed (Yes in step S15), the process proceeds to the next step S16. If it is determined that the predetermined time has not passed (No in step S15), the monitoring in step S15 continues.

[0077] In step S16, the control device 21 controls the valve 322 to close the valve 322. When the valve 322 is closed, the transport of the engine coolant used to supply heat is stopped. That is, the fluid transport mechanism 32 stops transporting the fluid when a predetermined time has elapsed since the start of the fluid transport. The supply of heat is stopped by stopping the transport of the fluid. Note that, at the timing when the valve 322 is closed, the grease filled in the gear case 2021 has been sufficiently warmed, and the operability of the steering wheel 12 is good. When the valve 322 is closed, the process proceeds to the next step S17.

[0078] In step S17, the control device 21 determines that the automatic steering function is available. The processing in step S17 is similar to that in step S5 of the first embodiment in Fig. 7, and therefore a detailed description thereof will be omitted. Once it is determined that the automatic steering function is available, the process proceeds to the next step, S18.

[0079] In step S18, the control device 21 controls the notification device 40 to perform notification processing to notify the driver that the automatic steering function is available. The explanation regarding the processing of step S18 is similar to the processing of step S6 in FIG. 7 of the first embodiment, and therefore a detailed explanation will be omitted. Completion of step S18 ends the processing shown in FIG. 9. After the processing shown in FIG. 9 ends, the processing from step S1 onwards shown in FIG. 9 may be repeated again.

[0080] In this example, when the engine coolant temperature becomes high, the transport of the engine coolant by the fluid transport mechanism 32 may be automatically stopped. Here, a high temperature refers to a temperature that is extremely higher than a predetermined temperature (such as 0°C), and may be, for example, a temperature of 80°C or higher.

[0081] <4. Modifications> [4-1. First Modification] In the above, the heat supply device 30 is configured to include only one of the electric heater 31 and the fluid transport mechanism 32. However, the heat supply device 30 may be configured to include both the electric heater 31 and the fluid transport mechanism 32.

[0082] Fig. 10 is a flowchart illustrating a method for selectively using the electric heater 31 and the fluid transport mechanism 32 when the heat supply device 30 includes the electric heater 31 and the fluid transport mechanism 32. The flow shown in Fig. 10 is started, for example, when the engine 3 of the tractor 1 is started. Note that in this modification, the electric heater 31 is not immediately put into an operating state (powered on) when the engine 3 is started.

[0083] In step S21, the control device 21 determines whether the temperature of the automatic steering mechanism 20 is below a predetermined temperature. As in the second embodiment described above, the predetermined temperature may be the lower limit of a temperature range in which the viscosity of the grease is not expected to adversely affect the operability of the steering wheel 12, such as 0°C. The temperature of the automatic steering mechanism 20 may be obtained, for example, from a temperature sensor that directly measures the temperatures of components that make up the automatic steering mechanism 20, such as the motor 201 and the gear mechanism 202. The temperature of the automatic steering mechanism 20 may also be obtained from a temperature sensor that can estimate the temperature of the automatic steering mechanism 20, such as the outside air temperature or the cabin temperature. If the temperature of the automatic steering mechanism 20 is below the predetermined temperature (Yes in step S21), the process proceeds to the next step S22. If the temperature of the automatic steering mechanism 20 is equal to or higher than the predetermined temperature (No in step S21), the supply of heat from the heat supply device is unnecessary, and the flow shown in FIG. 10 ends.

[0084] In step S22, the control device 21 determines whether the temperature obtained from the coolant temperature sensor 53 is below a predetermined temperature. If the temperature is below the predetermined temperature (Yes in step S22), the process proceeds to the next step S23. If the temperature is equal to or higher than the predetermined temperature (No in step S22), the process proceeds to step S24.

[0085] In step S23, the power supply to the electric heater 31 is turned on, and the supply of heat using the electric heater 31 is started. The subsequent processing may be the same as the processing shown in Fig. 7. In step S24, the supply of heat using the fluid transport mechanism 32 is started. The subsequent processing may be the same as the processing from step S12 onwards shown in Fig. 9.

[0086] That is, in this modification, when the temperature of the fluid is below a predetermined temperature, heat is supplied using the electric heater 31, and when the temperature of the fluid is equal to or higher than the predetermined temperature, heat is supplied using the fluid transport mechanism 32. By using them in this manner, heat can be efficiently supplied to the automatic steering mechanism 20 in a low-temperature environment.

[0087] [4-2. Second Modification] FIG. 11 is a block diagram illustrating a second modified example of a tractor 1 equipped with a heat supply device 30. In this modified example, the operation unit 25, through which an operator such as a driver inputs commands, has a switching operation unit 251 that switches from a state in which the steering wheel 12 is manually operated to a standby state in which automatic steering is awaited. That is, the tractor 1 of this modified example is equipped with a switching operation unit 251 that switches from a state in which the steering wheel 12 is manually operated to a standby state in which automatic steering is awaited. The standby state may be a preparation period for switching from manual to automatic. In the standby state, for example, the above-mentioned points A and B (see FIG. 3) may be registered. In addition, in the standby state, other settings related to automatic steering may be made possible.

[0088] The operation unit 25 including the switching operation unit 251 may be at least one of a configuration provided on the body 2 of the tractor 1 and a configuration provided on a mobile communication terminal (not shown) capable of communicating with the tractor 1. The switching operation unit 251 may be either a hardware switch or a software switch.

[0089] In a configuration provided with such a switching operation unit 251, the heat supply device 30 may be configured to start supplying heat when the switching operation unit 251 is operated to switch to the standby state. In detail, it is preferable that the heat supply by the heat supply device 30 be started when the temperature of the automatic steering mechanism 20 is below a predetermined temperature (such as 0°C).

[0090] The heat supply device 30 of this modified example may be, for example, the heat supply device 30A of the first embodiment or the heat supply device 30B of the second embodiment. Also in this modified example, when heat is being supplied using the heat supply device 30, the notification device 40 may notify the user that this is the case or that automatic steering using the automatic steering function cannot be started.

[0091] [4-3.Third Modification] 12 is a block diagram for explaining a third modified example of a tractor 1 equipped with a heat supply device 30. In this modified example, the operation unit 25A, through which an operator such as a driver inputs commands, has a start operation unit 252 that can instruct the heat supply device 30 to start supplying heat. In other words, the tractor 1 of this modified example is equipped with the start operation unit 252 that can instruct the heat supply device 30 to start supplying heat. Operation of the start operation unit 252 causes the heat supply device 30 to start supplying heat. With this configuration, the automatic steering mechanism 20 can be heated freely at a timing that the operator such as a driver feels is necessary.

[0092] The operation unit 25 including the start operation unit 252 may be configured as at least one of a configuration provided on the body 2 of the tractor 1 and a configuration provided on a mobile communication terminal (not shown) capable of communicating with the tractor 1. The start operation unit 252 may be either a hardware switch or a software switch. The start operation unit 252 configured as a hardware switch is preferably provided on the steering wheel 12 or the steering column 13.

[0093] Furthermore, the heat supply device 30 of this modified example may be, for example, the heat supply device 30A of the first embodiment or the heat supply device 30B of the second embodiment. Also in this modified example, when heat is being supplied using the heat supply device 30, the notification device 40 may notify the user that this is the case or that automatic steering using the automatic steering function cannot be started.

[0094] Also, in this modified example, the supply of heat by the heat supply device 30 may be conditional on the temperature of the automatic steering mechanism 20 being below a first temperature (see the first embodiment; for example, 0°C). That is, a configuration may be adopted in which the supply of heat by the heat supply device 30 is not performed even if the start operating unit 252 is operated when the temperature of the automatic steering mechanism 20 is equal to or higher than the first temperature. In such a configuration, a notification may be issued to prompt the operation of the start operating unit 252 when the temperature of the automatic steering mechanism 20 is below the first temperature. Furthermore, a notification may be issued to inform the user that the operation of the start operating unit 252 is invalid when the temperature of the automatic steering mechanism 20 is equal to or higher than the first temperature. Furthermore, after the start operating unit 252 is operated to start the supply of heat by the heat supply device 30, a notification may be issued to prompt the user to stop the supply of heat by the heat supply device 30 when the temperature of the automatic steering mechanism 20 reaches a second temperature (see the first embodiment; for example, 20°C).

[0095] Furthermore, the configuration may be such that operation of the start operating unit 252 is permitted on the condition that the state has been switched to the standby state by operation of the switching operating unit 251 (see FIG. 11) described above. In this case, too, the configuration may be such that operation of the start operating unit 252 is permitted on the condition that the temperature of the automatic steering mechanism 20 is below a first temperature (see the first embodiment; for example, 0°C). If operation by the start operating unit 252 is not permitted, a notification to that effect may be given. Furthermore, when operation by the start operating unit 252 is permitted, a notification to that effect may be given.

[0096] <5. Things to keep in mind> Various modifications can be made to the various technical features disclosed in this specification without departing from the spirit of the technical creation. Furthermore, multiple embodiments and modifications shown in this specification can be combined to the extent possible.

[0097] <6. Notes> An exemplary work vehicle of the present invention may be configured (first configuration) to include a steering wheel, an automatic steering mechanism that enables automatic steering of the steering wheel, and a heat supply device that is capable of supplying heat to the automatic steering mechanism.

[0098] The work vehicle of the first configuration above may be equipped with a steering shaft that supports the steering wheel, the automatic steering mechanism having a motor and a gear mechanism that transmits the rotational power of the motor to the steering shaft, and at least a part of the heat supply device may be arranged in the gear mechanism or its vicinity (second configuration).

[0099] In a work vehicle of the above first or second configuration, the heat supply device may include an electric heater arranged on a member that constitutes the automatic steering mechanism, and may be configured (third configuration) such that the electric heater starts supplying heat when the temperature of the automatic steering mechanism is below a first temperature.

[0100] In the work vehicle of the third configuration described above, the electric heater may be configured (fourth configuration) to stop supplying heat when the temperature of the automatic steering mechanism reaches a second temperature higher than the first temperature after the supply of heat has started.

[0101] In a work vehicle of the above first or second configuration, the heat supply device may be configured (fifth configuration) to include a fluid transport mechanism that transports fluid to the automatic steering mechanism, and when the temperature of the automatic steering mechanism is below a predetermined temperature, the fluid transport mechanism starts transporting the fluid to supply heat.

[0102] In the work vehicle of the fifth configuration, the fluid transporting mechanism may be configured (sixth configuration) to stop transport of the fluid when a predetermined time has elapsed since the start of transport of the fluid.

[0103] In the work vehicle of the fifth or sixth configuration, the fluid transported by the fluid transport mechanism may be a coolant for cooling the engine (seventh configuration).

[0104] In the work vehicle of the first configuration described above, the heat supply device may include an electric heater arranged on a member constituting the automatic steering mechanism, and a fluid transport mechanism that transports fluid to the automatic steering mechanism, and may be configured (eighth configuration) such that when the temperature of the fluid is below a predetermined temperature, heat is supplied using the electric heater, and when the temperature of the fluid is above the predetermined temperature, heat is supplied using the fluid transport mechanism.

[0105] The work vehicle of any one of the first to eighth configurations above may be configured (ninth configuration) such that the automatic steering is disabled while heat is being supplied by the heat supply device.

[0106] A work vehicle of any of the above configurations 1 to 9 may be equipped with a switching operation unit that switches the steering wheel from a state in which it is manually operated to a standby state in which it waits for the automatic steering to begin, and may be configured (configuration 10) in which the heat supply device starts supplying heat when the switching operation unit is operated to switch to the standby state.

[0107] A work vehicle of any of the above-mentioned configurations 1 to 10 may be configured (11th configuration) to be equipped with a start operating unit that can instruct the heat supply device to start supplying heat, and to cause the heat supply device to start supplying heat by operating the start operating unit. [Explanation of symbols]

[0108] 1. Tractor (work vehicle) 3. Engine 12. Steering wheel 14. Steering shaft 20. Automatic steering mechanism 30, 30A, 30B...Heat supply device 31 Electric heater 32 Fluid transport mechanism 201 Motor 202 Gear mechanism 251···Switching operation unit 252...Start operation section

Claims

1. A steering wheel, an automatic steering mechanism that enables automatic steering of the steering wheel; a heat supply device that is capable of supplying heat to the automatic steering mechanism; Equipped with A work vehicle, wherein the heat supply device includes a fluid transport mechanism that transports fluid to the automatic steering mechanism.

2. A work vehicle as described in claim 1, wherein the fluid transport mechanism begins transporting the fluid to supply heat when the temperature of the automatic steering mechanism is below a predetermined temperature.

3. a steering shaft supporting the steering wheel, The automatic steering mechanism includes: A motor; a gear mechanism that transmits the rotational power of the motor to the steering shaft; and The work vehicle according to claim 2 , wherein at least a portion of the heat supply device is disposed in or around the gear mechanism.

4. the heat supply device includes an electric heater disposed in a member constituting the automatic steering mechanism, The work vehicle according to claim 2 , wherein the electric heater starts supplying heat when the temperature of the automatic steering mechanism is lower than a first temperature.

5. The work vehicle according to claim 4 , wherein the electric heater stops supplying the heat when the temperature of the automatic steering mechanism reaches a second temperature higher than the first temperature after the start of supplying the heat.

6. The work vehicle according to claim 2 , wherein the fluid transporting mechanism stops transporting the fluid when a predetermined time has elapsed since starting to transport the fluid.

7. The work vehicle according to claim 2 , wherein the fluid transported by the fluid transport mechanism is a coolant for cooling the engine.

8. A steering wheel, an automatic steering mechanism that enables automatic steering of the steering wheel; a heat supply device that is capable of supplying heat to the automatic steering mechanism; Equipped with The heat supply device is an electric heater disposed in a member constituting the automatic steering mechanism; a fluid transport mechanism that transports fluid to the automatic steering mechanism; Including, A work vehicle in which, when the temperature of the fluid is below a predetermined temperature, heat is supplied using the electric heater, and, when the temperature of the fluid is equal to or higher than the predetermined temperature, heat is supplied using the fluid transport mechanism.

9. The work vehicle according to claim 2 , wherein the automatic steering is disabled while the heat supply device is supplying heat.

10. a switching operation unit that switches from a state in which the steering wheel is manually operated to a standby state in which the automatic steering is awaited; The work vehicle according to claim 2 , wherein when the switching operation unit is operated to switch to the standby state, the heat supply device starts supplying heat.

11. a start operation unit that can instruct the heat supply device to start supplying heat, The work vehicle according to claim 2 , wherein the heat supply device starts supplying heat in response to operation of the start operation unit.

Images