Work vehicles

Abstract

To provide a technology capable of upgrading the convenience of a work vehicle designed to be automatically steerable.SOLUTION: An exemplary work vehicle includes a steering wheel, a steering shaft that supports the steering wheel, a steering motor enabling automatic steering of the steering wheel, and a changeover mechanism that changes a power transmission condition, which is attained between the steering motor and steering shaft, between a connected condition and blocked condition.SELECTED DRAWING: Figure 7

Description

Technical Field

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

Background Art

[0002] Conventionally, a work vehicle having an automatic steering mechanism for automatically steering a steering wheel is known (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 capable of controlling the rotation direction, rotation speed, rotation angle, etc. based on the vehicle body position. The gear mechanism includes a gear provided on a steering shaft that rotatably supports the steering wheel and that rotates with the steering shaft, and a gear provided on the rotation shaft of the steering motor and that rotates with the rotation shaft. When the rotation shaft of the steering motor rotates, the steering shaft automatically rotates via the gear mechanism.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional work vehicle equipped with an automatic steering mechanism, the steering motor and the steering shaft are always connected via a gear mechanism. For this reason, when manual steering is performed during moving travel or when attaching / detaching a work implement, the steering motor becomes a resistance and the steering operation force (motor torque) increases. That is, there is a concern that the operability deteriorates during moving travel or when attaching / detaching a work implement. Further, when the motor torque increases, there is a concern about the accumulation of driver fatigue in cases where the moving travel takes a long time.

[0005] In view of the above points, the present invention aims to provide a technology that can improve the convenience of work vehicles equipped to be automatically steerable. [Means for solving the problem]

[0006] An exemplary work vehicle of the present invention comprises a steering wheel, a steering shaft supporting the steering wheel, a steering motor enabling automatic steering of the steering wheel, and a switching mechanism for switching the power transmission state between the steering motor and the steering shaft between a connected state and a disconnected state. [Effects of the Invention]

[0007] According to an exemplary example of the present invention, the convenience of a work vehicle that is equipped to be automatically steerable can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] Side view showing the schematic configuration of the tractor. [Figure 2] Block diagram showing the configuration related to the tractor's automatic steering function. [Figure 3] A diagram illustrating an example of how to set a baseline. [Figure 4] Side view showing the general configuration around the steering shaft. [Figure 5] A perspective view showing the schematic configuration of the gear mechanism with the gear case removed. [Figure 6A] A schematic diagram showing the switching mechanism, specifically the cutoff state. [Figure 6B] A schematic diagram showing the switching mechanism and the connection status. [Figure 7] Diagram illustrating the switching mechanism of modified examples. [Figure 8] A flowchart illustrating an example of control operation related to the switching mechanism when an automatic driving start operation is performed. [Figure 9] A flowchart illustrating an example of control operation related to the switching mechanism before the start of automated driving. [Figure 10] A flowchart illustrating an example of control operation related to the switching mechanism during autonomous driving. [Figure 11] A flowchart illustrating an example of control operation related to the switching mechanism when automatic driving is stopped. [Figure 12] A schematic diagram illustrating the gear ratios of a tractor. [Figure 13] A flowchart illustrating an example of control operation related to a gear shifting mechanism based on gear shift information. [Figure 14] A flowchart illustrating an example of control operation related to a switching mechanism based on the vehicle's position information. [Modes for carrying out the invention]

[0009] Embodiments 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 various harvesting machines, rice transplanters, combine harvesters, civil engineering and construction equipment, or snowplows.

[0010] Furthermore, in this specification, directions are defined as follows: First, the direction in which a tractor, as a work vehicle, moves during operation is defined as "forward," and the opposite direction is defined as "rear." Also, the right side in the direction of the tractor's movement is defined as "right," and the left side is defined as "left." The direction perpendicular to the front-rear and left-right directions of the tractor is defined as the up-down direction. 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 merely descriptive terms and are not intended to limit the actual positional relationships and directions.

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

[0012] At the front of the vehicle body 2, a pair of left and right front wheels 5 are arranged. At the rear of the vehicle body 2, a pair of left and right rear wheels 6 are arranged. The vehicle body 2 can travel by means of the front wheels 5 and the rear wheels 6. That is, the tractor 1 of the present 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 arranged at the front of the vehicle body 2, covered by the bonnet 7. The engine 3 is the driving source of the tractor 1. Note that the driving source of the tractor 1 may be another driving source such as an electric motor instead of the engine.

[0014] The transmission case 4 is arranged behind the engine 3 and below the driver's cab 8. The output of the engine 3 is transmitted to at least one of the front wheels 5 and the rear wheels 6 after being shifted by a transmission device (not shown) arranged in the transmission case 4.

[0015] The driver's cab 8 is provided behind the engine 3 in the vehicle body 2. The driver's cab 8 is the part where the driver (operator) rides. The driver's cab 8 includes a driver's seat 9 and a front panel 10. The driver's seat 9 is the place where the driver sits. The front panel 10 is arranged in front of the driver's seat 9. A steering wheel 11 is provided on the front panel 10. That is, the steering wheel 11 is arranged in front of the driver's seat 9. A meter display unit or the like indicating the speed of the tractor 1 is also provided on the front panel 10.

[0016] The steering wheel 11 includes a steering wheel 12 and a steering shaft 13 (see FIG. 2 and the like described later). That is, the tractor 1 includes a steering wheel 12 and a steering shaft 13. Note that the steering wheel 11 further includes a power steering device (not shown). The power steering device assists the manual steering of the steering wheel 12.

[0017] The steering wheel 12 is operated by the driver seated in the driver's seat 9. The steering shaft 13 supports the steering wheel 12. More specifically, the steering shaft 13 supports the steering wheel 12 in a manner that prevents relative rotation. That is, the steering wheel 12 and the steering shaft 13 rotate as a single unit. In Figure 1, the steering shaft 13 is covered by the steering column 14.

[0018] The steering wheel 12 and steering shaft 13 are rotatably supported by a member (not shown) located within the steering column 14. The steering shaft 13 is columnar and extends diagonally, tilted so that the upper part is more rearward than the lower part in the vertical direction (see Figure 4 below). The steering wheel 12 is located at the upper end of the steering shaft 13. The direction of the front wheels 5 can be changed by rotating the steering wheel 12.

[0019] The driver's unit 8 is also provided with various operating levers 15 and pedals 16, which are operated by the driver. The various operating levers 15 may include, for example, a main gear shift lever, an auxiliary gear shift lever, and a work lever. The various pedals 16 may include, for example, an accelerator pedal, a brake pedal, and a clutch pedal.

[0020] In this embodiment, a locating frame 17 is provided behind the driver's seat 9. The locating frame 17 can protect the driver in the event of the tractor 1 tipping over. Note that the tractor 1 may be a cabin type in which the driver's seat 9 is covered by a cabin, rather than a locating frame 17.

[0021] A work implement coupling section 18, consisting of a three-point linkage mechanism 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 tilling device, a plow, a fertilizer applicator, a pesticide sprayer, a harvesting device, or a mowing device. A lifting device (not shown) having a hydraulic system such as a lifting cylinder is also provided at the rear of the vehicle body 2. The lifting device can raise and lower 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 a transmission (not shown) located in the transmission case 4 and a power take-off shaft (PTO shaft; not shown) located at the rear of the vehicle body 2.

[0022] In this embodiment, the tractor 1 has an automatic steering function that autonomously steers the vehicle to follow a predetermined path. That is, the tractor 1 is designed to be able to travel by either manual steering, where 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. In addition to steering, the tractor 1 may also be configured to autonomously control at least one of the following: vehicle speed and work performed by implements.

[0023] As shown in Figure 2, the tractor 1 is equipped with a steering motor 31 that enables automatic steering of the steering wheel 12. The tractor 1 is also equipped with a gear mechanism 32 that is capable of transmitting the rotational power of the steering motor 31 to the steering shaft 13.

[0024] The steering motor 31 is provided so that its rotation direction, rotation speed, and rotation angle can be controlled. When the output shaft of the steering motor 31 rotates, rotational power is transmitted via the gear mechanism 32, causing the steering shaft 13 to rotate automatically. In other words, the steering wheel 12 can be rotated automatically by driving the steering motor 31. In this embodiment, the steering motor 31 and the gear mechanism 32 are located inside the steering column 14.

[0025] Furthermore, as shown in Figure 2, the tractor 1 is equipped with a control device 21. The control device 21 is a computer device comprising, for example, an arithmetic unit, an input / output unit, and a storage unit. The arithmetic unit is, for example, a processor or microprocessor. The storage unit is a main memory device such as ROM (Read Only Memory) and RAM (Random Access Memory). The storage unit may further include an auxiliary storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). Various programs and data are stored in the storage unit. The arithmetic unit reads various programs from the storage unit and performs arithmetic processing according to the programs.

[0026] The control device 21 may be singular or multiple. If there are multiple control devices 21, the configuration should be such that the multiple control devices can communicate with each other. The control device 21 is also positioned at an appropriate location on the vehicle body 2.

[0027] In this embodiment, the control device 21 controls automatic driving, including automatic steering. That is, the tractor 1 is equipped to perform automatic driving, including automatic steering. The control device 21 functions as a controller for automatic driving. Automatic driving means that the devices related to driving are controlled by the control device 21 of the tractor 1, so that at least steering is performed autonomously to follow a predetermined path. In addition to steering, automatic driving may also be configured so that at least one of the following is performed autonomously: for example, vehicle speed and work performed by implements.

[0028] The control device 21 is electrically connected to the steering motor 31 and controls the steering motor 31. The steering motor 31 is driven by power supplied by the control device 21. As described above, the driving force of the steering motor 31 is transmitted to the steering shaft 13 via the gear mechanism 32, so that the steering wheel 12 can be controlled by controlling the steering motor 31. In other words, the direction of the front wheels 5 can be controlled by controlling the steering motor 31.

[0029] In this embodiment, the control device 21 is electrically connected to the position acquisition unit 22 and the inertial measuring device 23. The position acquisition unit 22 and the inertial measuring device 23 are positioned appropriately on the vehicle body 2.

[0030] The position acquisition unit 22 uses positioning signals received from positioning satellites by a positioning antenna 24 located on the vehicle body 2 to acquire the position of the tractor 1, for example, as latitude and longitude information. In other words, the tractor 1 is equipped to acquire its own vehicle position information. The position acquisition unit 22 outputs the position information of the tractor 1 to the control device 21.

[0031] The position acquisition unit 22 may, for example, 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, the position acquisition unit 22 may perform positioning using a DGNSS (Differential GNSS) method.

[0032] The inertial measurement device 23 includes a three-axis angular velocity sensor and three-directional acceleration sensors. The inertial measurement device 23 outputs the measured information to the control device 21. The provision of the inertial measurement device 23 makes it possible to measure inertial information such as the yaw angle, pitch angle, and roll angle of the vehicle body 2.

[0033] The control device 21 performs automatic driving start and end processes in response to commands from an operator (driver, etc.) using an operation unit (not shown). The control device 21 also determines the position and orientation of the tractor body 2 based on information obtained from, for example, the position acquisition unit 22 and the inertial measuring device 23. The control device 21 also performs calculations related to automatic steering based on the relationship between the determined position of the body 2 and a predetermined automatic driving path, and controls the steering motor 31. Furthermore, the control device 21 performs the following calculations (for feedback control) based on the operation information of the steering motor 31.

[0034] Here, we will explain the outline of the automatic steering performed by the tractor 1 of this embodiment. When performing automatic steering, first, a reference line L is set. Figure 3 is a diagram illustrating one example of how to set the reference line L. The method for setting the reference line L may be other than the method shown in Figure 3.

[0035] When setting the baseline L, first, the tractor 1 is moved to a suitable location in the field (point A in the diagram), 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 point A registration command is issued is registered as the position of point A.

[0036] Once point A is registered, the driver manually moves tractor 1 in a straight line to the designated position (point B in the diagram). When tractor 1 reaches the designated position, point B is registered. Point B 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 point B registration command 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.

[0037] When a reference line L is set, lines parallel to the reference line L are generated as automatic driving lines at predetermined intervals. During automatic steering, steering control of the tractor 1's direction of travel is performed so that the automatic driving lines and the position of the vehicle body 2 acquired by the position acquisition unit 22 coincide. Steering control of the tractor 1's direction of travel is performed by controlling the steering motor 31.

[0038] <2. Details of the relationship between the steering shaft and the steering motor> Figure 4 is a side view showing the schematic configuration of the area around the steering shaft 13 of the tractor 1 according to this embodiment. As shown in Figure 4, the gear mechanism 32 has a gear case 321.

[0039] The gear case 321 is supported by a support member (not shown) within the steering column 14. The gear case 321 rotatably supports the steering shaft 13. In this embodiment, the gear case 321 has an upper case 321a and a lower case 321b. The upper case 321a and the lower case 321b are stacked on top of each other and fixed together using fasteners such as bolts and nuts. Multiple gears 322 (see Figure 5, described later) of the gear mechanism 32 are arranged in the internal space created by stacking the upper case 321a and the lower case 321b.

[0040] The steering motor 31 is fixed to the upper case 321a, and most of it is located outside the upper case 321a. The output shaft 311 of the steering motor 31 (see Figure 5 below) protrudes into the gear case 321.

[0041] Figure 5 is a perspective view showing the schematic configuration of the gear mechanism 32 with the gear case 321 removed. Note that Figure 5 also includes elements other than the gear mechanism 32. As shown in Figure 5, a shaft bearing 323 fixed to the gear case 321 is arranged inside the gear case 321. The steering shaft 13 is rotatably supported by the gear case 321 via the shaft bearing 323. Also, as shown in Figure 5, two rotating shafts 324 and 325 are arranged inside the gear case 321, rotatably supported by bearings (not shown) fixed to the gear case 321.

[0042] As shown in Figure 5, the gear mechanism 32 includes a plurality of gears 322. The plurality of gears 322 include a first gear 322a, a second gear 322b, a third gear 322c, a fourth gear 322d, a fifth gear 322e, and a sixth gear 322f.

[0043] The first gear 322a is mounted on the output shaft 311 of the steering motor 31 and rotates together with the output shaft 311. The second gear 322b is mounted on the first rotating shaft 324 and rotates together with the first rotating shaft 324. The second gear 322b meshes with the first gear 322a. That is, when the first gear 322a rotates, the second gear 322b also rotates. The third gear 322c is mounted on the same first rotating shaft 324 as the second gear 322b and rotates together with the first rotating shaft 324. That is, when the second gear 322b rotates, the third gear 322c also rotates.

[0044] The fourth gear 322d is mounted on the second rotating shaft 325 and rotates together with the second rotating shaft 325. The fourth gear 322d meshes with the third gear 322c. That is, when the third gear 322c rotates, the fourth gear 322d also rotates. The fifth gear 322e is mounted on the same second rotating shaft 325 as the fourth gear 322d and rotates together with the second rotating shaft 325. That is, when the fourth gear 322d rotates, the fifth gear 322e also rotates. The sixth gear 322f is mounted on the steering shaft 13 and rotates together with the steering shaft 13. The sixth gear 322f meshes with the fifth gear 322e. That is, when the fifth gear 322e rotates, the sixth gear 322f also rotates. As can be seen from the above, when the steering motor 31 is driven and the output shaft 311 rotates, the rotational force is transmitted to the steering shaft 13 via the multiple gears 322, causing the steering shaft 13 to rotate.

[0045] In this embodiment, the tractor 1 is equipped with a switching mechanism that switches the power transmission state between the steering motor 31 and the steering shaft 13 between a connected state and a disconnected state. In the above description, it is assumed that this switching mechanism is in the connected state, and the transmission of rotational power from the steering motor 31 is described accordingly.

[0046] The switching mechanism is a so-called clutch. The switching mechanism allows the power transmission between the steering motor 31 and the steering shaft 13 to be connected when automatic steering is performed. Conversely, the power transmission between the steering motor 31 and the steering shaft 13 can be disconnected when manual steering is performed.

[0047] By interrupting the power transmission between the steering motor 31 and the steering shaft 13 during manual steering, the steering motor 31 can be prevented from becoming a source of resistance during manual steering. In other words, the operability of the tractor 1, which is equipped to be automatically steerable, can be improved. Furthermore, the accumulation of driver fatigue can be reduced, for example, when moving the vehicle using manual steering.

[0048] <3. Switching mechanism> Next, a detailed example of the switching mechanism described above will be explained. Figures 6A and 6B schematically show the switching mechanism 41 provided in the tractor 1 of this embodiment. Figure 6A shows the switching mechanism 41 in the disconnected state. Figure 6B shows the switching mechanism 41 in the connected state. In this embodiment, the switching mechanism 41 is included in the steering motor 31. In other words, the steering motor 31 of this embodiment is a so-called motor with a clutch. The steering motor 31 is configured to include a motor body 310 that includes a rotating shaft 312 that rotates when power is supplied to the motor 31, and a switching mechanism 41 that is arranged on one end side of the rotating shaft 312.

[0049] The switching mechanism 41 comprises a stator 411, a rotor 412, an output shaft 413, and an armature 414. The switching mechanism 41 is a so-called electromagnetic clutch.

[0050] The stator 411 includes a coil and is configured as an electromagnet. The stator 411 is fixedly positioned within the case 313 that constitutes the steering motor 31. The stator 411 is positioned to surround one end of the rotating shaft 312. The stator 411 functions as a magnet when switch 411a is turned on and energized. The stator 411 does not function as a magnet when switch 411a is turned off and no energized.

[0051] The rotor 412 is a flat clutch plate. The rotor 412 is connected to one end of the rotating shaft 312 and rotates together with the rotating shaft 312. The surface of the rotor 412 is perpendicular to the axis of the rotating shaft 312.

[0052] The output shaft portion 413 has a flat plate portion 413a and a shaft portion 413b. The flat plate portion 413a and the shaft portion 413b are a single component. The flat plate portion 413a is positioned opposite the rotor 412 at a distance in the axial direction of the rotating shaft 312. The plate surface of the flat plate portion 413a is parallel to the plate surface of the rotor 412. The flat plate portion 413a is rotatably arranged within the case 313. The shaft portion 413b extends in the axial direction of the rotating shaft 312, with the same axis position as the rotating shaft 312. In this example, the shaft portion 413b constitutes the output shaft 311 of the steering motor 31. That is, the first gear 322a described above is attached to the tip side of the shaft portion 413b.

[0053] The armature 414 is positioned on the side of the flat plate portion 413a opposite to the side where the shaft portion 413b is provided. The armature 414 is attached to the flat plate portion 413a via an elastic member 415, such as a leaf spring. When the switch 411a is off, the armature 414 is positioned away from the rotor 412 (see Figure 6A). When the switch 411a is turned on, the armature 414 is attracted to the stator 411, which functions as a magnet, and comes into close contact with the rotor 412, which is positioned between the stator 411 and the flat plate portion 413a (see Figure 6B). That is, when the switch 411a is turned on, the output shaft portion 413 becomes rotatable together with the rotor 412. When the switch 411a is turned off, the armature 414 is not attracted to the stator 411 and is pulled towards the flat plate portion 413a by the elastic force of the elastic member 415. As a result, the armature 414 becomes separated from the rotor 412 (see Figure 6A).

[0054] As can be seen from the above, when switch 411a is off, the switching mechanism 41 disconnects the power transmission between the steering motor 31 and the steering shaft 13. When switch 411a is on, the switching mechanism 41 connects the power transmission between the steering motor 31 and the steering shaft 13. When automatic steering is performed, by turning switch 411a on, the rotational power of the steering motor 31 is transmitted to the steering shaft 13, allowing for proper automatic steering. When manual steering is performed, by turning switch 411a off, the steering wheel 12 can be easily operated without receiving resistance from the steering motor 31.

[0055] Figure 7 is a diagram illustrating a modified switching mechanism 41A. The modified switching mechanism 41A is a mechanical clutch. The switching mechanism 41A can switch the power transmission state between the steering motor 31 and the steering shaft 13 between a connected state and a disconnected state by operating a switching operating member (not shown). The switching operating member may be, for example, a clutch lever or a clutch pedal. The operation of the switching operating member may be performed manually by the driver, for example. However, the switching operating member may be provided to be automatically operated by a machine. In this modified example, the steering motor 31 is not provided with the above-described switching mechanism 41, and the steering motor 31 is simply a motor.

[0056] More specifically, the switching mechanism 41A switches the connection relationship between the gear mechanism 32 and the steering shaft 13. More specifically, the switching mechanism 41A switches the connection relationship between the gear mechanism 32 and the steering shaft 13 between connected and disconnected. When the gear mechanism 32 and the steering shaft 13 are disconnected, the power transmission between the steering motor 31 and the steering shaft 13 is interrupted. When the gear mechanism 32 and the steering shaft 13 are connected, the power transmission between the steering motor 31 and the steering shaft 13 is connected.

[0057] In this configuration, when the steering wheel 12 is operated with the switching mechanism 41A in the off state, it is possible to avoid not only the resistance of the steering motor 31 but also the resistance of the gear mechanism 32. This improves the operability of the steering wheel 12 when manually steering. The gear case 321, which houses the multiple gears 322 that make up the gear mechanism 32, is usually filled with grease (not shown) for the purpose of lubricating the gears 322. The grease filling the gear mechanism 32 tends to cause resistance when moving it, but in this modified configuration, manual steering can be performed without being affected by the resistance caused by such grease filling.

[0058] In this modified example, the sixth gear 322f constituting the gear mechanism 32 is not integrated with the steering shaft 13. The sixth gear 322f is rotatably mounted relative to the steering shaft 13. The switching mechanism 41A includes two friction plates (not shown) positioned to sandwich the steering shaft 13. Each friction plate is fixed to the steering shaft 13, for example by splinting, and rotates together with the steering shaft 13.

[0059] When the switching mechanism 41A is in the disengaged state, each friction plate is separated from the sixth gear 322f, and even when the steering shaft 13 is rotated, the sixth gear 322f does not rotate. In other words, when the steering wheel 12 is rotated, the steering wheel 12 can be easily operated without receiving resistance from the gear mechanism 32 and the steering motor 31.

[0060] When the switching mechanism 41A is operated and changed from the disconnected state to the connected state, each friction plate is pressed against the sixth gear 322f. As a result, when the steering shaft 13 is rotated, the sixth gear 322f rotates along with each friction plate. In other words, in the connected state, when the steering motor 31 is driven, rotational power is transmitted to the steering shaft 13 via the gear mechanism 32.

[0061] In this modified example, the switching mechanism 41A, which consists of a mechanical clutch, is provided between the steering shaft 13 and the gear mechanism 32, but this is merely an example. The switching mechanism, which consists of a mechanical clutch, may be provided, for example, between the output shaft 311 of the steering motor 31 and the gear mechanism 32. Alternatively, the switching mechanism, which consists of a mechanical clutch, may be provided within the gear mechanism 32. Furthermore, the switching mechanism provided between the steering shaft 13 and the gear mechanism 32 is not limited to a mechanical clutch, but may be composed of, for example, an electromagnetic clutch.

[0062] <4. Examples of control operations related to the switching mechanism> Next, an example of control operation related to the switching mechanisms 41 and 41A in the tractor 1 will be described. The control operation can be performed by the control device 21 described above.

[0063] [4-1. Examples of control operations related to autonomous driving] Figure 8 is a flowchart showing an example of control operation related to the switching mechanisms 41 and 41A when an automatic driving start operation is performed. The automatic driving start operation is performed, for example, using an operation unit provided on the tractor 1 or on a portable communication terminal (not shown) that is capable of communicating with the tractor 1.

[0064] In step S1, the control device 21 determines whether the switching mechanisms 41 and 41A are connected or not. For example, if the switching mechanism 41 is composed of an electromagnetic clutch, the control device 21 can determine whether the switching mechanism 41 is connected or not by checking the on / off state of the switch 411a (see Figure 6A, etc.). Alternatively, if the switching mechanism 41A is composed of a mechanical clutch, the control device 21 can determine whether the switching mechanism 41A is connected or not based on information from a sensor that detects the state of a switching operating member such as a clutch lever. If it is determined that the switching mechanisms 41 and 41A are connected (Yes in step S1), the process proceeds to step S2. If it is determined that the switching mechanisms 41 and 41A are disconnected (No in step S1), the process proceeds to step S3.

[0065] In step S2, the control device 21 determines that the switching mechanisms 41 and 41A are in a state where automatic steering can be performed, and therefore initiates the process of starting automatic driving. In other words, in this example, if the switching mechanisms 41 and 41A are connected when the automatic driving start operation is performed, automatic driving will start. Since automatic driving is started only after it has been confirmed that the switching mechanisms 41 and 41A are in the appropriate state, automatic driving can be started safely.

[0066] In step S3, if the switching mechanism is, for example, a switching mechanism 41 composed of an electromagnetic clutch, the control device 21 performs a process to automatically connect the switching mechanism 41. Specifically, the control device 21 performs a control process to turn on the switch 411a. As a result, the switching mechanism 41 switches from the disconnected state to the connected state. Also, if the switching mechanism is, for example, a switching mechanism 41A composed of a mechanical clutch, the control device 21 performs a process to notify the driver or others that the switching mechanism 41A is being switched to the connected state. As a result, a notification device installed on the tractor 1 or a portable communication terminal installed to communicate with the tractor 1 will notify the driver or others to connect the switching mechanism 41A. The notification method using the notification device may be, for example, a screen display or voice guidance. When the processing in step S3 is completed, the process returns to step S1, and the processing from step S1 onwards is performed.

[0067] Even if the switching mechanism is a mechanical switching mechanism 41A, if the switching operation member such as the clutch lever can be operated automatically, the switching mechanism 41A may be configured to be automatically connected.

[0068] As can be seen from the above, in this example, when the automatic driving start operation is performed, it is confirmed whether the switching mechanisms 41 and 41A are in a connected state or a disconnected state. With this configuration, automatic driving can be started after it is confirmed that the switching mechanisms 41 and 41A are in a connected state. In other words, automatic driving can be started safely.

[0069] Furthermore, in this example, if the switching mechanisms 41 and 41A are in a disconnected state when the automatic driving start operation is performed, the switching mechanism 41 will be automatically connected, or a notification will be issued prompting the switching mechanism 41A to be connected. In this example, the possibility of automatic driving starting with the switching mechanisms 41 and 41A in a disconnected state can be reduced. In other words, automatic driving can be started safely.

[0070] Figure 9 is a flowchart illustrating an example of control operation related to the switching mechanisms 41 and 41A before the start of automatic driving. In this example, it is assumed that conditions for permitting the start of automatic driving (start conditions) are set in advance. For example, when the start conditions are met, the driver or other person is notified that the start conditions have been met, and when the driver or other person performs the operation to start automatic driving, automatic driving begins. Another example is that when the start conditions are met, automatic driving starts automatically.

[0071] In step S11, the control device 21 monitors whether the conditions for starting automatic driving have been met. The conditions for starting automatic driving are, for example, met when the vehicle reaches within a predetermined distance from a preset automatic driving start position. Alternatively, the conditions for starting automatic driving are met when the angle of the vehicle with respect to a preset automatic driving start path is within a predetermined angle. There may be one or more conditions for starting automatic driving. If it is determined that the conditions for starting driving have been met (Yes in step S11), the process proceeds to the next step S12. If it is determined that the conditions for starting driving have not been met (No in step S11), the process in step S11 is repeated. That is, the process in step S11 is repeated until the conditions for starting driving are met.

[0072] The starting conditions may also include the temperature at which the gear case 321 is filled is above a predetermined temperature. The predetermined temperature may be, for example, the lower limit of the 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 appropriately by experimentation or other means.

[0073] In step S12, the control device 21 determines whether the switching mechanisms 41 and 41A are connected or not. This determination process is the same as in step S1 in Figure 8 described above. If it is determined that the switching mechanisms 41 and 41A are connected (Yes in step S12), the process ends because the switching mechanisms 41 and 41A are in a state suitable for automatic steering. On the other hand, if it is determined that the switching mechanisms 41 and 41A are disconnected (No in step S12), the process proceeds to step S13.

[0074] In step S13, if the switching mechanism is, for example, an electromagnetic clutch-based switching mechanism 41, the control device 21 performs a process to automatically connect the switching mechanism 41. Also, if the switching mechanism is a mechanical clutch-based switching mechanism 41A, the control device 21 performs a process to notify the driver or other relevant party that the switching mechanism 41A is being switched to the connected state. These processes are the same as in step S3 in Figure 8 above. Once the process in step S13 is completed, the process returns to step S12, and the processes from step S12 onward are performed.

[0075] As can be seen from the above, in this example, if the switching mechanisms 41 and 41A are in a disconnected state when it is determined that the conditions for starting automatic driving have been met, the switching mechanisms 41 and 41A are automatically connected, or a notification is issued prompting the switching mechanisms 41 and 41A to be connected. With this configuration, the switching mechanisms 41 and 41A can be kept in a disconnected state until just before automatic driving starts. Then, as soon as the conditions for starting automatic driving are met, the switching mechanisms 41 and 41A can be quickly switched to a connected state suitable for automatic driving.

[0076] Furthermore, the notification prompting the switching mechanisms 41 and 41A to be connected may include a configuration that simply notifies that the conditions for starting automatic driving have been met.

[0077] Furthermore, the tractor 1 may be configured to include an operating unit (switch, etc.) for transitioning to a standby state (standby mode) that waits for the start of automatic driving. Note that the standby state may be a preparation period when switching from manual to automatic. In the standby state, for example, it may be possible to register points A and B (see Figure 3) as described above. In addition, other settings related to automatic driving may be possible in the standby state. In a configuration that allows transition to such a standby state, if the switching mechanisms 41 and 41A are in the disconnected state when the transition to the standby state occurs, the switching mechanisms 41 and 41A may be automatically connected, or a notification may be given prompting the switching mechanisms 41 and 41A to be connected. Note that since the registration of point A, etc. is performed by manual steering, if the registration of point A, etc. is performed in the standby state, the configuration may be such that a process is performed to automatically connect the switching mechanisms 41 and 41A at an appropriate timing after the manual steering related to the registration is completed.

[0078] Figure 10 is a flowchart illustrating an example of control operation related to the switching mechanisms 41 and 41A during automatic driving. At the start of the process in Figure 10, the tractor 1 is in automatic driving mode. Also, at the start of the process in Figure 10, the switching mechanisms 41 and 41A are in a connected state. Furthermore, Figure 10 assumes that during automatic driving, for some reason, the switching mechanisms 41 and 41A may switch from a connected state to a disconnected state.

[0079] In step S21, the control device 21 monitors whether the switching mechanisms 41 and 41A are in a disconnected state. For example, if the switching mechanism 41 is composed of an electromagnetic clutch, it is determined that the switching mechanism 41 is in a disconnected state when the switch 411a (see Figure 6A, etc.) is turned off. Alternatively, if the switching mechanism 41A is composed of a mechanical clutch, it is determined whether the switching mechanism 41A is in a disconnected state based on information from a sensor that detects the state of a switching operating member such as a clutch lever. If it is determined that the switching mechanisms 41 and 41A are in a disconnected state (Yes in step S21), the process proceeds to the next step S22. If it is determined that they are in a connected state (No in step S21), the process in step S21 is repeated. That is, the process in step S21 is repeated until a disconnected state is detected.

[0080] Furthermore, the switching of the switching mechanisms 41 and 41A from the connected state to the disconnected state during automatic driving may be performed, for example, when the driver or other operator operates the operating section of the switching mechanisms 41 and 41A. This operation by the driver or other operator may be intentional or unintentional. Also, for example, the switching of the switching mechanisms 41 and 41A from the connected state to the disconnected state during automatic driving may be performed when an abnormality occurs in the steering motor 31. Also, for example, the switching of the switching mechanisms 41 and 41A from the connected state to the disconnected state during automatic driving may be performed when the driver operates the steering wheel 12. Whether or not the driver has operated the steering wheel 12 can be determined, for example, by monitoring the load value (e.g., current value) of the steering motor 31. Also, whether or not the driver has operated the steering wheel 12 can be determined by monitoring information from the steering angle sensor that measures the steering angle.

[0081] In step S22, the control device 21 determines whether or not it is necessary to stop the vehicle. For example, if it is possible that the switching of the switching mechanisms 41 and 41A to the shut-off state occurred unintentionally, the control device 21 determines that it is necessary to stop the vehicle for safety reasons. An example of such a case is when a malfunction occurs in the steering motor 31 and the switching mechanisms 41 and 41A are shut off. Also, for example, if it is determined that the switching of the switching mechanisms 41 and 41A to the shut-off state was caused by an intentional action by the driver, the control device 21 may determine that it is not necessary to stop the vehicle. An example of a case where it is determined that the vehicle is not necessary to stop is when the driver operates the steering wheel 12 and the switching mechanisms 41 and 41A are shut off. If it is determined that it is necessary to stop the vehicle (Yes in step S22), the process proceeds to step S23. If it is determined that it is not necessary to stop the vehicle (No in step S22), the process proceeds to step S24.

[0082] In step S23, the control device 21 performs a process to bring the vehicle to a stop. It is preferable that the driver or other relevant personnel are notified when this stopping process is performed.

[0083] In step S24, the control device 21 performs a process to stop automatic driving. However, the control device 21 does not perform the process of stopping the vehicle. When the process of stopping automatic driving is performed, it is preferable that the driver or other relevant parties are notified of this fact.

[0084] As can be seen from the above, in this example, if the switching mechanisms 41 and 41A are shut off during automatic driving, the automatic driving will stop or a stopping process will be performed. By configuring it in this way, it is possible to prevent automatic driving from continuing in a state that is unsuitable for automatic driving.

[0085] In addition, as a configuration different from the above examples, the vehicle may be configured to stop in all cases if the switching mechanisms 41 and 41A are in a shut-off state during automatic driving. That is, in the flow shown in Figure 10, the determination process in step S22 may be omitted.

[0086] Figure 11 is a flowchart showing an example of control operation related to the switching mechanisms 41 and 41A when automatic driving is stopped. Automatic driving can be stopped, for example, in response to instructions from the driver or other person. Alternatively, automatic driving can be stopped automatically based on the judgment of the control device 21.

[0087] For example, the following are cases in which automatic driving may be stopped: In a field, the tractor may be driven automatically only along a planned straight path, with the driver of tractor 1 manually navigating the turning paths connecting the straight paths. In such a configuration, automatic driving will be stopped once the automatic driving along the straight path is completed. Also, for example, during automatic driving, tractor 1 may deviate from the pre-set automatic driving path due to the presence of a slope or slippage. In such cases, automatic driving will be stopped.

[0088] In step S31, the control device 21 determines whether the switching mechanisms 41 and 41A are in a disconnected state. This determination process is the same as in step S21 in Figure 10 described above. If it is determined that the switching mechanisms 41 and 41A are in a disconnected state (Yes in step S31), the process ends because the switching mechanisms 41 and 41A are in a state suitable for manual steering. On the other hand, if it is determined that the switching mechanisms 41 and 41A are in a connected state (No in step S31), the process proceeds to step S32.

[0089] In step S32, if the switching mechanism is, for example, a switching mechanism 41 composed of an electromagnetic clutch, the control device 21 performs a process to automatically put the switching mechanism 41 into a disconnected state. Specifically, the control device 21 performs a control process to turn off the switch 411a. As a result, the switching mechanism 41 switches from the connected state to the disconnected state. Also, if the switching mechanism is, for example, a switching mechanism 41A composed of a mechanical clutch, the control device 21 performs a process to notify the driver or others that the switching mechanism 41A is being switched to the disconnected state. As a result, a notification device installed on the tractor 1 or a portable communication terminal installed to communicate with the tractor 1 will make a notification prompting the driver to put the switching mechanism 41A into the disconnected state. The notification method using the notification device may be, for example, a screen display or voice guidance. When the processing in step S32 is completed, the process returns to step S31, and the processing from step S31 onwards is performed.

[0090] As can be seen from the above, in this example, if the switching mechanisms 41 and 41A are connected when automatic driving is stopped, the switching mechanism 41 is automatically disconnected, or a notification is given prompting the driver to disconnect the switching mechanism 41A. With this configuration, it is less likely that the driver will forget to disconnect the switching mechanisms 41 and 41A after automatic driving has stopped. For example, because it is less likely that the switching mechanisms 41 and 41A will be disconnected after driving on a straight path, the driver can easily operate the turning path that follows the straight path with manual steering.

[0091] [4-2. Other Control Operation Examples] Figure 12 is a schematic diagram illustrating the gear ratios of the tractor 1 of this embodiment. As shown in Figure 12, the tractor 1 is equipped with a sub-gear lever 151. The sub-gear lever 151 is an operating device for selecting, for example, one of two speeds (low speed and high speed). The driver or operator specifies a rough speed using the sub-gear lever 151, and then specifies a finer speed using the main gear lever (not shown). The sub-gear may be switchable to three or more speeds. In this case, it is preferable that the three or more sub-gear ratios are divided into either a low-speed ratio (low speed side) for field work and a high-speed ratio (high speed side) for road (outside the field) driving. For example, in the case of three speeds, there may be one low-speed ratio, one high-speed ratio, and two high-speed ratios.

[0092] In other words, the tractor 1 is equipped with a transmission 4a having a low-speed gear used during field work and a high-speed gear used at times other than the aforementioned work. Information on the gear of the transmission 4a is input to the control device 21. The gear information may be, for example, information from a sensor that detects the lever position of the auxiliary transmission lever 151.

[0093] Figure 13 is a flowchart showing an example of control operation related to the gear shifting mechanisms 41 and 41A based on gear shift information.

[0094] In step S41, the control device 21 monitors whether the gear of the sub-transmission is a high gear. If the gear is a high gear (Yes in step S41), the process proceeds to the next step S42. If the gear is a low gear (No in step S41), the process in step S41 is repeated. In other words, the process in step S41 is repeated until it is detected that the gear is a high gear.

[0095] In step S42, the control device 21 determines whether the switching mechanisms 41 and 41A are connected or not. This determination process is the same as in step S1 in Figure 8 described above. If it is determined that the switching mechanisms 41 and 41A are connected (Yes in step S42), the process proceeds to the next step S43. On the other hand, if it is determined that the switching mechanisms 41 and 41A are disconnected (No in step S42), the process returns to step S41.

[0096] In step S43, if the switching mechanism is, for example, an electromagnetic clutch-based switching mechanism 41, the control device 21 performs a process to automatically shut off the switching mechanism 41. Also, if the switching mechanism is a mechanical clutch-based switching mechanism 41A, the control device 21 performs a process to notify the driver or others that the switching mechanism 41A has been switched to the shut-off state. These processes are the same as those in step S32 in Figure 11 described above.

[0097] As can be seen from the above, in this example, if the transmission 4a is in a high gear and the switching mechanisms 41 and 41A are connected, the switching mechanism 41 is automatically disconnected, or a notification is given prompting the driver to disconnect the switching mechanism 41A. This prevents the driver from forgetting to switch the switching mechanisms 41 and 41A from connected to disconnected when the transmission is in a high gear. For example, when driving on the road, the switching mechanisms 41 and 41A can be reliably disconnected, making driving on the road easier.

[0098] Furthermore, if an abnormality in the steering motor 31 is detected during automatic driving, or if the load on the steering motor 31 exceeds a predetermined value, the control device 21 may, as in this example, automatically shut off the switching mechanism 41, or perform notification processing to prompt the switching mechanism 41A to shut off.

[0099] Figure 14 is a flowchart illustrating an example of control operation related to the switching mechanisms 41 and 41A based on the vehicle's position information. In this example, it is assumed that field information, including the location of the field, is pre-registered in a memory unit (not shown) of the tractor 1. The vehicle's position information is input to the control device 21 from the position acquisition unit 22 (see Figure 2).

[0100] In step S51, the control device 21 monitors whether the vehicle is located outside the field. If the vehicle is located outside the field (Yes in step S51), the process proceeds to the next step S52. If the vehicle is located inside the field (No in step S51), the process in step S51 is repeated. In other words, the process in step S51 is repeated until it is detected that the vehicle is located outside the field.

[0101] In step S52, the control device 21 determines whether the switching mechanisms 41 and 41A are connected or not. This determination process is the same as in step S1 in Figure 8 described above. If it is determined that the switching mechanisms 41 and 41A are connected (Yes in step S52), the process proceeds to the next step S53. On the other hand, if it is determined that the switching mechanisms 41 and 41A are disconnected (No in step S52), the process returns to step S51.

[0102] In step S53, if the switching mechanism is, for example, an electromagnetic clutch-based switching mechanism 41, the control device 21 performs a process to automatically shut off the switching mechanism 41. Also, if the switching mechanism is a mechanical clutch-based switching mechanism 41A, the control device 21 performs a process to notify the driver or others that the switching mechanism 41A has been switched to the shut-off state. These processes are the same as those in step S32 in Figure 11 described above.

[0103] As can be seen from the above, in this example, if the vehicle is determined to be outside the field and the switching mechanisms 41 and 41A are connected, the switching mechanism 41 is automatically disconnected, or a notification is issued prompting the driver to disconnect the switching mechanism 41A. This prevents the driver from forgetting to switch the switching mechanisms 41 and 41A from connected to disconnected when the vehicle is outside the field. As a result, the driver can easily perform off-field driving, which is normally done manually.

[0104] Alternatively, when it is determined that the vehicle is located within the field, the switching mechanism 41 may be automatically switched to the connected state, or a notification may be issued prompting the switching mechanism 41A to be switched to the connected state.

[0105] <5. Things to keep in mind> Various technical features disclosed herein can be modified in various ways without departing from the spirit of the technical creation. Furthermore, the multiple embodiments and modifications shown herein may be combined as possible.

[0106] <6. Addendum> An exemplary work vehicle of the present invention may have a configuration (first configuration) comprising: a steering wheel; a steering shaft supporting the steering wheel; a steering motor enabling automatic steering of the steering wheel; and a switching mechanism for switching the power transmission state between the steering motor and the steering shaft between a connected state and a disconnected state.

[0107] The work vehicle in the first configuration described above includes a gear mechanism that is provided to transmit the rotational power of the steering motor to the steering shaft, and the switching mechanism may be configured to switch the connection relationship between the gear mechanism and the steering shaft (second configuration).

[0108] The work vehicle of the first or second configuration described above may be configured to be capable of performing automatic driving, including automatic steering, and if the switching mechanism is in the connected state when the operation to start the automatic driving is performed, the automatic driving may be started (third configuration).

[0109] A work vehicle having any of the first to third configurations described above may be configured to be capable of performing automatic driving, including automatic steering, and if the switching mechanism is in the disconnected state when the operation to start the automatic driving is performed, the switching mechanism may be automatically switched to the connected state, or a notification may be given prompting the switching mechanism to be switched to the connected state (fourth configuration).

[0110] A work vehicle having any of the first to fourth configurations described above may be configured to be capable of automatic driving, including automatic steering, and if the switching mechanism is in the connected state when the automatic driving is stopped, the switching mechanism may be automatically switched to the disconnected state, or a notification may be given prompting the switching mechanism to be switched to the disconnected state (fifth configuration).

[0111] A work vehicle having any of the above configurations 1 to 5 may be configured to be capable of automatic driving, including automatic steering, and to stop the automatic driving or perform a stopping process if the switching mechanism enters the shut-off state while driving by automatic driving (configuration 6).

[0112] A work vehicle having any of the above configurations 1 to 6 is equipped with a transmission having a low-speed gear used when working in a field and a high-speed gear used when not working, and if the transmission is in the high-speed gear and the switching mechanism is in the connected state, the switching mechanism is automatically switched to the disconnected state, or a notification is given prompting the switching mechanism to be switched to the disconnected state (configuration 7).

[0113] A work vehicle having any of the above configurations 1 to 7 may be provided with the ability to acquire its own location information, and when it is determined that the vehicle is located outside the field, if the switching mechanism is in the connected state, the switching mechanism may be automatically switched to the disconnected state, or a notification may be issued prompting the switching mechanism to be switched to the disconnected state (configuration 8).

[0114] A work vehicle having any of the above configurations 1 to 8 may be configured to be capable of performing automatic driving, including automatic steering, and when it is determined that the conditions for starting the automatic driving have been met, if the switching mechanism is in the disconnected state, the switching mechanism will be automatically connected, or a notification will be given prompting the switching mechanism to be connected (configuration 9). [Explanation of symbols]

[0115] 1. Tractor (work vehicle) 4a... Transmission 12. Steering wheel 13. Steering shaft 31. Steering motor 32. Gear mechanism 41, 41A... Switching mechanism

Claims

1. The steering wheel and A steering shaft that supports the aforementioned steering wheel, A steering motor that enables automatic steering of the steering wheel, A switching mechanism for switching the power transmission state between the steering motor and the steering shaft between a connected state and a disconnected state, A work vehicle equipped with the above-mentioned automatic steering and capable of performing automatic driving, A work vehicle in which, when the switching mechanism enters the shut-off state during automatic driving, it is determined whether or not it is necessary for the vehicle to stop, and depending on the result of the determination, the automatic driving is stopped or a stopping process is performed.

2. The steering motor is equipped with a gear mechanism that can transmit rotational power to the steering shaft, The work vehicle according to claim 1, wherein the switching mechanism switches the connection relationship between the gear mechanism and the steering shaft.

3. The work vehicle according to claim 1 or 2, wherein if the switching mechanism is in the connected state when the automatic driving start operation is performed, the automatic driving is started.

4. The work vehicle according to claim 1 or 2, wherein if the switching mechanism is in the disconnected state when the automatic driving start operation is performed, the switching mechanism is automatically switched to the connected state, or a notification is given prompting the switching mechanism to be switched to the connected state.

5. The work vehicle according to claim 1 or 2, wherein if the switching mechanism is in the connected state when the automatic driving is stopped, the switching mechanism is automatically switched to the disconnected state, or a notification is given prompting the switching mechanism to be switched to the disconnected state.

6. A steering wheel and A steering shaft that supports the aforementioned steering wheel, A steering motor that enables automatic steering of the steering wheel, A switching mechanism for switching the power transmission state between the steering motor and the steering shaft between a connected state and a disconnected state, It is equipped with a transmission having a low-speed gear for use during field work and a high-speed gear for use at times other than the aforementioned work. A work vehicle in which, when the transmission is in the high-speed gear and the switching mechanism is in the connected state, the switching mechanism is automatically switched to the disconnected state, or a notification is issued prompting the switching mechanism to be switched to the disconnected state.

7. A steering wheel and A steering shaft that supports the aforementioned steering wheel, A steering motor that enables automatic steering of the steering wheel, A switching mechanism for switching the power transmission state between the steering motor and the steering shaft between a connected state and a disconnected state, Equipped with, It is designed to acquire the location information of the vehicle, A work vehicle in which, when it is determined that the vehicle is located outside the field, if the switching mechanism is in the connected state, the switching mechanism is automatically switched to the disconnected state, or a notification is issued prompting the switching mechanism to be switched to the disconnected state.

8. The work vehicle according to claim 1 or 2, wherein if the switching mechanism is in the disconnected state when it is determined that the conditions for starting automatic driving have been met, the switching mechanism is automatically switched to the connected state, or a notification is given prompting the switching mechanism to be switched to the connected state.

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