JP7163178B2 - work vehicle - Google Patents

Description

The present invention relates, for example, to work vehicles.

Conventionally, patent document 1 is known as an agricultural working machine. The agricultural work machine of Patent Document 1 includes a traveling machine body capable of switching between manual traveling by manual steering and automatic traveling by automatic steering along a set traveling line set parallel to a reference traveling line, and manual traveling and automatic traveling. and a changeover switch that can freely switch between running and running. In addition, the starting point of the reference travel line is set after pressing the right instruction button while the agricultural implement is traveling along the ridge, and the end point of the reference travel line is set by pressing the left instruction button while traveling. That is, the reference travel line is set before automatic steering.

The work vehicle of Patent Document 2 has front wheel turning angle detection means for detecting that the turning angle of the front wheels of the work vehicle has exceeded a predetermined value, and switches to a double speed state in which the front wheels rotate at a faster ground speed than the rear wheels. and double speed switching means.

JP 2017-123803 A JP 2014-94592 A

In the agricultural implement disclosed in Patent Document 1, automatic travel can be easily performed by switching from manual travel to automatic travel using a changeover switch. It is being considered to provide the agricultural implement of Patent Document 1 with the double speed switching means disclosed in Patent Document 2.
Now, in agricultural implements, the number of rotations of the drive shaft on the rear wheel side is replaced by the running speed, and it is not assumed that it is attached to the front wheel side. In particular, when a double-speed switching means is provided, the number of revolutions of the drive shaft on the front wheel side increases, so the actual situation is that the running speed cannot be accurately detected.

Therefore, in view of the above problems, the present invention provides a work vehicle capable of manual steering and automatic steering, which is provided with a speed doubler and a rotation detection device for detecting the traveling speed on the drive shaft on the front wheel side. It is an object of the present invention to provide a working vehicle capable of properly detecting traveling speed even in such a case.

The technical means of the present invention for solving this technical problem are characterized by the following points.
The work vehicle has a steering handle and
A vehicle body provided with a traveling device including front wheels and rear wheels, and capable of traveling by either manual steering by the steering handle or automatic steering by the steering handle based on a traveling reference line; and steering by the steering handle. A transmission including a speed doubler that makes the rotation speed of the front wheels faster than the rotation speed of the rear wheels when the angle is equal to or greater than a predetermined value, and a rotation that detects the rotation speed of the front wheel drive shaft from the transmission to the front wheels By multiplying a first rotation speed, which is the rotation speed of the front-wheel drive shaft detected by the detection device and the rotation detection device when the speed doubler is not operating, by a conversion coefficient for converting the rotation speed to speed, A first calculation unit that calculates the running speed of the vehicle body, and a second rotation speed that is the rotation speed of the front wheel drive shaft detected by the rotation detection device when the speed doubler is operating. The running speed of the vehicle body is calculated by subtracting the increased number of revolutions, which is the amount of increase in the number of revolutions between the time of operation and the time of operation of the double speed device, and multiplying the subtracted number of revolutions by the conversion factor. a second calculating unit for calculating; and displaying the running speed of the vehicle body calculated by the first calculating unit when the speed doubler is not in operation, and displaying the second speed when the speed doubler is in operation. and a display device for displaying the traveling speed of the vehicle body calculated by the calculation unit .

The second calculation unit has a calculation formula for calculating the increased rotation speed based on the second rotation speed, and obtains the subtraction rotation speed based on the second rotation speed and the calculation formula.

The work vehicle comprises a steering changeover switch for switching between starting and ending the automatic steering, and automatic steering for starting automatic steering of the steering handle when the steering changeover switch switches the start of the automatic steering . and a control unit .
The work vehicle includes a positioning device capable of detecting the position of the vehicle body, and a reference line setting switch for setting the position of the vehicle body detected by the positioning device to the starting position and the ending position of the traveling reference line. .

According to the present invention, in a work vehicle that can be manually steered and automatically steered, even if a speed doubling device is provided and a rotation detection device for detecting the traveling speed is provided on the drive shaft on the front wheel side, Running speed can be detected.

It is a figure which shows the structure of a tractor, and a control block diagram. It is an explanatory view explaining automatic steering. It is an explanatory view explaining the amount of correction in a push switch. FIG. 5 is an explanatory diagram for explaining correction amounts in a slide switch; It is a figure which shows the 1st correction|amendment part and the 2nd correction|amendment part in a push switch. It is a figure which shows the 1st correction|amendment part and the 2nd correction|amendment part in a slide switch. The figure shows a state in which the calculated vehicle body position deviates to the right while the vehicle is traveling straight under automatic steering. This shows the state when the calculated vehicle body position deviates to the left while the vehicle is traveling straight under automatic steering. It is the figure which looked at the cover ahead of the driver's seat from the driver's seat side. It is an explanatory view explaining automatic steering. It is a figure which shows a raising/lowering apparatus. It is a figure which shows the operation screen M1. It is a figure which shows the operation screen M2. 1 is an overall view of a tractor; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 10 is a side view showing one embodiment of the work vehicle 1, and FIG. 10 is a plan view showing one embodiment of the work vehicle 1. As shown in FIG. In this embodiment, work vehicle 1 is a tractor. However, the work vehicle 1 is not limited to a tractor, and may be an agricultural machine (agricultural vehicle) such as a combine harvester or a transplanter, or a construction machine (construction vehicle) such as a loader working machine.

Hereinafter, the front side of the driver seated in the driver's seat 10 of the tractor (work vehicle) 1 (direction of arrow A1 in FIG. 10) is the front side, the rear side of the driver (direction of arrow A2 in FIG. 10) is the rear side, and the left side of the driver. will be described as the left side and the driver's right side as the right side. Also, the horizontal direction, which is the direction orthogonal to the front-rear direction of the work vehicle 1, will be described as the width direction of the vehicle body.
As shown in FIG. 10 , the tractor 1 includes a vehicle body 3 , a prime mover 4 and a transmission 5 . The vehicle body 3 has a traveling device 7 and can travel. The traveling device 7 is a device having front wheels 7F and rear wheels 7R. The front wheels 7F may be of a tire type or a crawler type. Also, the rear wheel 7R may be of a tire type or a crawler type.

The prime mover 4 is a diesel engine, an electric motor, or the like, and is configured by a diesel engine in this embodiment. The transmission device 5 can switch the driving force of the traveling device 7 by changing speed, and can switch the traveling device 7 between forward and reverse. A driver's seat 10 is provided in the vehicle body 3 .
A connecting portion including a lifting device 8 is provided at the rear portion of the vehicle body 3 . A working device can be attached to and detached from the connecting portion. By connecting the working device to the connecting portion, the working device can be towed by the vehicle body 3 . The work equipment includes a tillage device for tilling, a fertilizer spraying device for spraying fertilizer, an agricultural chemical spraying device for spraying agricultural chemicals, a harvesting device for harvesting, a reaper for cutting pasture, a spreading device for spreading pasture, and a sprayer for pasture. It is a grass collection device that collects grass such as grass, a forming device that forms pasture grass, and the like.

As shown in FIG. 1, the transmission 5 includes a main shaft (propulsion shaft) 5a, a main transmission portion 5b, an auxiliary transmission portion 5c, a shuttle portion 5d, a PTO power transmission portion 5e, a front transmission portion 5f, It has The propelling shaft 5a is rotatably supported by a housing case (mission case) of the transmission 5, and power from the crankshaft of the prime mover 4 is transmitted to the propelling shaft 5a. The main transmission portion 5b has a plurality of gears and a shifter for changing the connection of the gears. The main transmission section 5b changes the rotation input from the propulsion shaft 5a and outputs it (changes speed) by appropriately changing the connection (engagement) of a plurality of gears with a shifter.

The auxiliary transmission portion 5c has a plurality of gears and a shifter for changing the connection of the gears, like the main transmission portion 5b. The sub-transmission portion 5c appropriately changes the connection (engagement) of a plurality of gears with a shifter, thereby changing and outputting (shifting) the rotation input from the main transmission portion 5b.
The shuttle portion 5 d has a shuttle shaft 12 and a forward/reverse switching portion 13 . Power output from the auxiliary transmission portion 5c is transmitted to the shuttle shaft 12 via gears or the like. The forward/reverse switching unit 13 is composed of, for example, a hydraulic clutch or the like, and switches the rotation direction of the shuttle shaft 12, that is, the forward/reverse of the tractor 1, by turning on/off the hydraulic clutch. The shuttle shaft 12 is connected to the rear wheel differential device 20R. The rear wheel differential device 20R rotatably supports a rear axle 21R to which the rear wheels 7R are attached.

The PTO power transmission section 5 e has a PTO propulsion shaft 14 and a PTO clutch 15 . The PTO propulsion shaft 14 is rotatably supported and can transmit power from the propulsion shaft 5a. The PTO propulsion shaft 14 is connected to the PTO shaft 16 via a gear or the like. The PTO clutch 15 is composed of, for example, a hydraulic clutch or the like, and the power of the propelling shaft 5a is transmitted to the PTO propelling shaft 14 or not transmitted to the PTO propelling shaft 14 by turning on or off the hydraulic clutch. state.

The front transmission portion 5 f has a first clutch 17 and a second clutch 18 . The first clutch 17 and the second clutch can transmit power from the propulsion shaft 5a, for example, the power of the shuttle shaft 12 is transmitted via gears and transmission shafts. Power from the first clutch 17 and the second clutch 18 can be transmitted to the front wheels 7F by a front wheel drive shaft 23 that extends forward from the transmission 5 and reaches the front wheels 7F. The front wheel drive shaft 23 includes a front transmission shaft 22 rotatably supported by the transmission case of the transmission 5 and extending forward, and a front axle 21F rotatably supported by the front wheel differential device 20F. The front end of the front transmission shaft 22 is connected to a front wheel differential device 20F. The front axle 21F extends left and right from the front wheel differential device 20F, and the left front axle 21F rotates the left front wheel 7F. The right front axle 21F rotatably supports the right front wheel 7F.

The first clutch 17 and the second clutch 18 are composed of hydraulic clutches or the like. An oil passage is connected to the first clutch 17, and the oil passage is connected to a first operating valve 25 to which hydraulic oil discharged from a hydraulic pump is supplied. The first clutch 17 switches between a connected state and a disconnected state depending on the degree of opening of the first operating valve 25 . An oil passage is connected to the second clutch 18 , and the oil passage is connected to a second operating valve 26 . The second clutch 18 switches between a connected state and a disconnected state depending on the degree of opening of the second operating valve 26 . The first operating valve 25 and the second operating valve 26 are, for example, two-position switching valves with electromagnetic valves, and are switched between a connected state and a disconnected state by energizing or demagnetizing the solenoids of the electromagnetic valves.

The work vehicle 1 is provided with a double speed device. The speed doubling device is a device that makes the rotational speed of the front wheels 7F faster than the rotational speed of the rear wheels 7R when the steering angle of the steering handle 30, which will be described later, is greater than or equal to a predetermined steering angle (or greater than the steering angle corresponding to turning). In this embodiment, the speed doubler includes a first clutch 17, a second clutch 18, a first operating valve 25 and a second operating valve . For example, when the first operating valve 25 engages the first clutch 17 and the second operating valve 26 disengages the second clutch 18, four-wheel drive is established and the rotational speed of the front wheels is equal to that of the rear wheels. It becomes faster than the speed (4WD acceleration state).

When the first clutch 17 is in the disengaged state and the second clutch 18 is in the engaged state, the power of the shuttle shaft 12 is transmitted to the front wheels 7F through the second clutch 18. As a result, four-wheel drive (4WD) is achieved in which the front and rear wheels are driven by power, and the rotational speeds of the front and rear wheels are approximately the same (4WD constant speed state). Further, when the first clutch 17 and the second clutch 18 are disengaged, the power of the shuttle shaft 12 is not transmitted to the front wheels 7F, so that the rear wheels are driven by the power, resulting in two-wheel drive (2WD).

As shown in FIG. 8, the lifting device 8 has a lift arm 8a, a lower link 8b, a top link 8c, a lift rod 8d and a lift cylinder 8e. A front end portion of the lift arm 8a is supported by a rear upper portion of a case (transmission case) that houses the transmission 5 so as to be capable of swinging upward or downward. The lift arm 8a swings (moves up and down) by being driven by a lift cylinder 8e. The lift cylinder 8e is composed of a hydraulic cylinder. The lift cylinder 8e is connected via a control valve 29 to a hydraulic pump. The control valve 29 is an electromagnetic valve or the like, and expands and contracts the lift cylinder 8e.

A front end portion of the lower link 8b is supported by a lower rear portion of the transmission 5 so as to be capable of swinging upward or downward. A front end portion of the top link 8c is supported by the rear portion of the transmission 5 above the lower link 8b so as to be able to swing upward or downward. The lift rod 8d connects the lift arm 8a and the lower link 8b. The working device 2 is connected to the rear portion of the lower link 8b and the rear portion of the top link 8c. When the lift cylinder 8e is driven (extended and retracted), the lift arm 8a moves up and down, and the lower link 8b connected to the lift arm 8a via the lift rod 8d moves up and down. As a result, the work device 2 swings upward or downward (elevates) with the front portion of the lower link 8b as a fulcrum.

The tractor 1 has a positioning device 40 . The positioning device 40 can detect its own position (positioning information including latitude and longitude) using satellite positioning systems (positioning satellites) such as D-GPS, GPS, GLONASS, Hokuto, Galileo, and Michibiki. That is, the positioning device 40 receives satellite signals (position of the positioning satellite, transmission time, correction information, etc.) transmitted from the positioning satellite, and detects the position (for example, latitude and longitude) based on the satellite signal. The positioning device 40 has a receiving device 41 and an inertial measurement unit (IMU: Inertial Measurement Unit) 42 . The receiving device 41 is a device that has an antenna or the like and receives satellite signals transmitted from a positioning satellite, and is attached to the vehicle body 3 separately from the inertial measurement device 42 . In this embodiment, the receiving device 41 is attached to a rope provided on the vehicle body 3 . Note that the mounting location of the receiving device 41 is not limited to the embodiment.

The inertial measurement device 42 has an acceleration sensor that detects acceleration, a gyro sensor that detects angular velocity, and the like. The roll angle, pitch angle, yaw angle, etc. of the vehicle body 3 can be detected by the inertial measurement device 42 provided below the vehicle body 3 , for example, the driver's seat 10 .
As shown in FIG. 1 , the tractor 1 has a steering device 11 . The steering device 11 is a device capable of manual steering in which the vehicle body 3 is steered by a driver's operation and automatic steering in which the vehicle body 3 is automatically steered without being operated by the driver.

The steering device 11 has a steering handle (steering wheel) 30 and a steering shaft (rotating shaft) 31 that rotatably supports the steering handle 30 . The steering device 11 also has an auxiliary mechanism (power steering device) 32 . The assist mechanism 32 assists the rotation of the steering shaft 31 (steering handle 30) by hydraulic pressure or the like. The auxiliary mechanism 32 includes a hydraulic pump 33 , a control valve 34 to which hydraulic oil discharged from the hydraulic pump 33 is supplied, and a steering cylinder 35 operated by the control valve 34 . The control valve 34 is, for example, a three-position switching valve that can be switched by movement of a spool or the like, and switches in accordance with the steering direction (rotational direction) of the steering shaft 31 . The steering cylinder 35 is connected to an arm (knuckle arm) 36 for turning the front wheels 7F.

Therefore, when the driver grips the steering handle 30 and operates it in one direction or the other, the switching position and the degree of opening of the control valve 34 are switched corresponding to the rotation direction of the steering handle 30, and the control valve 34 The steering direction of the front wheels 7F can be changed by extending and retracting the steering cylinder 35 to the left or right according to the switching position and opening degree of . In other words, the vehicle body 3 can change its traveling direction to the left or right by manually steering the steering handle 30 .

Next, automatic steering will be described.
As shown in FIG. 2, when performing automatic steering, first, a driving reference line L1 is set before performing automatic steering. After setting the driving reference line L1, automatic steering can be performed by setting a planned driving line L2 parallel to the driving reference line L1. In the automatic steering, the tractor 1 (body 3) is automatically steered in the direction of travel so that the vehicle body position measured by the positioning device 40 and the planned travel line L2 coincide with each other.

Specifically, before automatic steering is performed, the tractor 1 (body 3) is moved to a predetermined position in the field (S1), and the driver operates the steering switch 52 provided on the tractor 1 at the predetermined position. Then (S2), the vehicle body position measured by the positioning device 40 is set to the starting point P10 of the travel reference line L1 (S3). Further, the tractor 1 (body 3) is moved from the starting point P10 of the traveling reference line L1 (S4), and when the driver operates the steering changeover switch 52 at a predetermined position (S5), the positioning device 40 measures The vehicle body position is set at the end point P11 of the running reference line L1 (S6). Therefore, a straight line connecting the start point P10 and the end point P11 is set as the travel reference line L1.

After setting the traveling reference line L1 (after S6), for example, the tractor 1 (vehicle body 3) is moved to a location different from the location where the traveling reference line L1 is set (S7), and the driver operates the steering changeover switch 52. (S8), a planned travel line L2, which is a straight line parallel to the travel reference line L1, is set (S9). After the planned travel line L2 is set, automatic steering is started, and the traveling direction of the tractor 1 (body 3) is changed to follow the planned travel line L2. For example, if the current vehicle body position is on the left side of the planned travel line L2, the front wheels 7F are steered to the right. is steered to the left. During automatic steering, the running speed (vehicle speed) of the tractor 1 (vehicle body 3) can be changed by the driver manually changing the operation amount of the accelerator member (accelerator pedal, accelerator lever) provided on the tractor 1, It can be changed by changing the speed of the transmission.

Further, after the automatic steering is started, the automatic steering can be terminated when the driver operates the steering changeover switch 52 at an arbitrary position. That is, the end point of the planned travel line L2 can be set by the end of automatic steering by operating the steering changeover switch 52 . That is, the length from the start point to the end point of the planned travel line L2 can be set longer or shorter than the travel reference line L1. In other words, the planned travel line L2 is not associated with the length of the reference travel line L1, and the planned travel line L2 allows the vehicle to travel a longer distance than the length of the reference travel line L1 while being automatically steered.

As shown in FIG. 1 , the steering device 11 has an automatic steering mechanism 37 . The automatic steering mechanism 37 is a mechanism for automatically steering the vehicle body 3 , and automatically steers the vehicle body 3 based on the position of the vehicle body 3 (vehicle position) detected by the positioning device 40 . The automatic steering mechanism 37 has a steering motor 38 and a gear mechanism 39 . The steering motor 38 is a motor whose rotation direction, rotation speed, rotation angle, etc. can be controlled based on the position of the vehicle body. The gear mechanism 39 includes a gear provided on the steering shaft 31 and rotating together with the steering shaft 31, and a gear provided on the rotating shaft of the steering motor 38 and rotating together with the rotating shaft. When the rotating shaft of the steering motor 38 rotates, the steering shaft 31 automatically rotates (turns) via the gear mechanism 39, and the steering direction of the front wheels 7F is adjusted so that the vehicle body position coincides with the planned travel line L2. can be changed.

As shown in FIG. 1, the tractor 1 has a display device 45 . The display device 45 is a device that can display various information about the tractor 1 , and can display at least the operation information of the tractor 1 . The display device 45 is provided in front of the driver's seat 10 .
As shown in FIG. 1 , the tractor 1 has a setting switch 51 . The setting switch 51 is a switch for switching to a setting mode in which at least settings before the start of automatic steering are performed. The setting mode is a mode in which various settings related to the automatic steering are performed before the automatic steering is started.

The setting switch 51 can be switched ON or OFF, and outputs a signal indicating that the setting mode is valid when it is ON, and outputs a signal indicating that the setting mode is invalid when it is OFF. The setting switch 51 outputs a signal indicating that the setting mode is valid to the display device 45 when it is ON, and outputs a signal indicating that the setting mode is invalid to the display device 45 when it is OFF.

The tractor 1 has a steering changeover switch 52 . The steering changeover switch 52 is a switch for switching between starting and ending automatic steering. Specifically, the steering selector switch 52 can be switched upward, downward, forward, or rearward from the neutral position, and when it is switched downward from the neutral position while the setting mode is valid, the automatic steering is started. When the setting mode is valid and the position is switched upward from the neutral position, the end of the automatic steering is output. Further, when the steering changeover switch 52 is switched from the neutral position to the rear while the setting mode is valid, the steering changeover switch 52 outputs to set the current vehicle body position to the start point P10 of the traveling reference line L1, and the steering changeover switch 52 52 outputs that the current vehicle body position is set to the end point P11 of the running reference line L1 when the neutral position is switched forward while the setting mode is valid. That is, the steering changeover switch 52 also serves as a reference line setting switch for setting the start position (start point P10) and end position (end point P11) of the travel reference line L1. The steering changeover switch 52 may be configured separately from the steering changeover switch 52 for switching the start or end of the automatic steering and the reference line setting switch.

The tractor 1 has a correction switch 53 . The correction switch 53 is a switch for correcting the vehicle body position (latitude, longitude) measured by the positioning device 40 . That is, the correction switch 53 is used to calculate the vehicle body position (calculated vehicle body position) from the satellite signals (position of the positioning satellite, transmission time, correction information, etc.) and measurement information (acceleration, angular velocity) measured by the inertial measurement device 42. ) is a switch for correcting

The correction switch 53 is composed of a depressible push switch or a slidable slide switch. A case where the correction switch 53 is a push switch or a slide switch will be described below.
When the correction switch 53 is a push switch, the correction amount is set based on the number of times the push switch is operated. The correction amount is determined by correction amount=number of operations×correction amount per one operation. For example, as shown in FIG. 3A, the correction amount increases by several centimeters or several tens of centimeters each time the push switch is operated. The number of push switch operations is input to the first control device 60A, and the first control device 60A sets (calculates) the correction amount based on the number of operations.

Further, when the correction switch 53 is a slide switch, the correction amount is set based on the operation amount (displacement amount) of the slide switch. For example, the correction amount is determined by correction amount=displacement amount from a predetermined position. For example, as shown in FIG. 3B, every time the displacement amount of the slide switch increases by 5 mm, the correction amount increases by several centimeters or several tens of centimeters. The operation amount (displacement amount) of the slide switch is input to the first control device 60A, and the first control device 60A sets (calculates) the correction amount based on the displacement amount. It should be noted that the method of increasing the correction amount and the rate of increase described above are not limited to the numerical values described above.

Specifically, as shown in FIGS. 4A and 4B, the correction switch 53 has a first correction section 53A and a second correction section 53B. The first correction section 53A is a section that commands correction of the vehicle body position corresponding to one side in the width direction of the vehicle body 3, that is, the left side. The second correction section 53B is a section that commands correction of the vehicle body position corresponding to the other side in the width direction of the vehicle body 3, that is, the right side.

As shown in FIG. 4A, when the correction switch 53 is a push switch, the first correction section 53A and the second correction section 53B are ON or OFF switches that automatically return each time they are operated. The switches forming the first correction section 53A and the switches forming the second correction section 53B are integrated. The switches forming the first correction section 53A and the switches forming the second correction section 53B may be arranged apart from each other. As shown in FIG. 3A, each time the first correction portion 53A is pressed, the correction amount corresponding to the left side of the vehicle body 3 (left correction amount) increases. Also, every time the second correction portion 53B is pressed, the correction amount corresponding to the right side of the vehicle body 3 (right correction amount) increases.

As shown in FIG. 4B, when the correction switch 53 is a slide switch, the first correction portion 53A and the second correction portion 53B include a knob portion 55 that moves left or right along the longitudinal direction of the slot. there is When the correction switch 53 is a slide switch, the first correction portion 53A and the second correction portion 53B are arranged apart from each other in the width direction. As shown in FIG. 3B, when the knob portion 55 is gradually displaced leftward from a predetermined reference position, the left correction amount increases according to the amount of displacement. Further, when the knob portion 55 is gradually displaced to the right from the predetermined reference position, the right correction amount increases according to the amount of displacement. As shown in FIG. 4B, in the case of a slide switch, the first correction portion 53A and the second correction portion 53B are integrally formed, the reference position of the knob portion 55 is set at the center, and the The left correction amount may be set when the knob 55 is moved to the left, and the right correction amount may be set when the knob 55 is moved to the right from the intermediate position.

Next, the relationship between the correction amount (left correction amount, right correction amount) by the correction switch 53, the planned travel line L2, and the behavior (travel locus) of the tractor 1 (vehicle body 3) will be described.
FIG. 5A shows a state in which the calculated vehicle body position W1 deviates to the right while the vehicle is traveling straight under automatic steering. As shown in FIG. 5A, when the automatic steering is started, the actual position (actual position W2) of the tractor 1 (vehicle body 3) and the calculated vehicle body position W1 match, and the actual position W2 and the planned travel line If L2 matches, the tractor 1 travels along the planned traveling line L2. That is, in the section P1 where there is no positioning error in the positioning device 40 and the vehicle body position (calculated vehicle body position W1) detected by the positioning device 40 is the same as the actual position W2, the tractor 1 travels along the scheduled travel line L2. . When there is no error in positioning by the positioning device 40 and no correction is performed, the calculated vehicle body position W1 and the corrected vehicle body position (corrected vehicle body position) W3 are the same. The corrected vehicle body position W3 is the corrected vehicle body position W3=calculated vehicle body position W1−correction amount.

Here, in the vicinity of the position P20, although the actual position W2 is not deviated from the planned travel line L2, due to various influences, an error occurs in the positioning of the positioning device 40, and the position is detected by the positioning device 40. If the vehicle body position W1 deviates to the right with respect to the planned travel line L2 (actual position W2) and the deviation amount W4 is maintained, the tractor 1 will be operated in such a manner that there is a deviation between the calculated vehicle body position W1 and the planned travel line L2. Then, the tractor 1 is steered to the left so as to eliminate the amount of deviation W4 between the calculated vehicle body position W1 and the planned travel line L2. Then, the actual position W2 of the tractor 1 is shifted to the planned travel line L2 by left steering. Assume that the driver thereafter notices that the tractor 1 is deviated from the planned travel line L2, and steers the second correction unit 53B at position P21 to increase the right correction amount from zero. A right correction amount is added to the calculated vehicle body position W1, and the vehicle body position after correction (corrected vehicle body position) W3 can be substantially the same as the actual position W2. That is, by setting the right correction amount by the second correction unit 53B, the vehicle body position of the positioning device 40 can be corrected in the direction of eliminating the deviation amount W4 generated near the position P20. As indicated by position P21 in FIG. 5A, when the actual position W2 of the tractor 1 is away from the planned travel line L2 to the left after correcting the vehicle body position, the tractor 1 is steered to the right. The actual position W2 can be matched with the planned travel line L2.

FIG. 5B shows a state in which the calculated vehicle body position W1 deviates to the left while the vehicle is traveling straight under automatic steering. As shown in FIG. 5B, when the actual position W2 and the calculated vehicle body position W1 match and the actual position W2 and the planned travel line L2 match in a state in which the automatic steering is started, as shown in FIG. Similarly, the tractor 1 travels along the scheduled travel line L2. 5A, the tractor 1 travels along the scheduled travel line L2 in the section P2 where the positioning device 40 has no positioning error. Further, similarly to FIG. 5A, the calculated vehicle body position W1 and the corrected vehicle body position W3 are the same value.

Here, at the position P22, various influences cause an error in the positioning of the positioning device 40, causing the vehicle body position W1 detected by the positioning device 40 to deviate to the left with respect to the actual position W2, and the deviation amount W5 is maintained. If so, the tractor 1 is steered to the right so as to eliminate the amount of deviation W5 between the calculated vehicle body position W1 and the planned travel line L2. After that, assume that the driver notices that the tractor 1 is deviated from the planned travel line L2 and steers the first correction unit 53A at position P23 to increase the left correction amount from zero. Then, the left correction amount is added to the calculated vehicle body position W1, and the vehicle body position after correction (corrected vehicle body position) W3 can be substantially the same as the actual position W2. That is, by setting the left correction amount by the first correction unit 53A, the vehicle body position of the positioning device 40 can be corrected in the direction of eliminating the deviation amount W5 generated near the position P22. As indicated by position P23 in FIG. 5B, when the actual position W2 of the tractor 1 is away from the planned travel line L2 to the right after correcting the vehicle body position, the tractor 1 is steered to the left. The actual position W2 can be matched with the planned travel line L2.

Next, the setting switch 51 and the correction switch 53 will be explained.
As shown in FIG. 6, the outer circumference of the steering shaft 31 is covered with a steering post 180. As shown in FIG. The outer circumference of steering post 180 is covered with cover 177 . The cover 177 is provided in front of the driver's seat 10 . Cover 177 includes panel cover 178 and column cover 179 .

A panel cover 178 supports the display device 45 . A support portion 178 e that supports the display device 45 is provided on the upper plate portion 178 a of the panel cover 178 . The support portion 178 e supports the display device 45 in front of the steering shaft 31 and below the steering handle 30 . The upper plate portion 178a also has a mounting surface 178f on which the setting switch 51 and the correction switch 53 are mounted. The mounting surface 178f is provided behind the support portion 178e and below the steering handle 30. As shown in FIG. The support portion 178e and the mounting surface 178f are continuous, the support portion 178e being positioned in front of the upper plate portion 178a, and the mounting surface 178f being positioned in the rear portion of the upper plate portion 178a. The setting switch 51 and the correction switch 53 are attached to the attachment surface 178f. Accordingly, the setting switch 51 and the correction switch 53 are arranged around the steering shaft 31 .

A shuttle lever 181 protrudes from the left plate portion 178b of the panel cover 178. As shown in FIG. The shuttle lever 181 is a member that operates to switch the running direction of the vehicle body 3 . More specifically, by operating (swinging) the shuttle lever 181 forward, the forward/reverse switching unit 13 is brought into a state of outputting forward driving power to the traveling device 7, and the traveling direction of the vehicle body 3 is switched to the forward direction. Further, by operating (swinging) the shuttle lever 181 rearward, the forward/reverse switching portion 13 is brought into a state of outputting reverse driving power to the traveling device 7, and the traveling direction of the vehicle body 3 is switched to the backward traveling direction. Power is not output to the traveling device 7 when the shuttle lever 181 is in the neutral position.

The column cover 179 is arranged below the steering handle 30 and covers the upper portion of the steering shaft 31 . The column cover 179 is formed in a substantially square tubular shape and protrudes upward from the mounting surface 178f of the panel cover 178. As shown in FIG. That is, the mounting surface 178f is provided around the column cover 179. As shown in FIG. Therefore, the setting switch 51 and the correction switch 53 attached to the attachment surface 178f are arranged around the column cover 179. As shown in FIG.

Next, the arrangement of the setting switch 51, the steering switch 52, and the correction switch 53 will be described in detail. As shown in FIG. 6 , the setting switch 51 , the steering changeover switch 52 and the correction switch 53 are arranged around the steering shaft 31 .
The setting switch 51 is arranged on one side (left side) of the steering shaft 31 . The steering changeover switch 52 is arranged on one side (left side) of the steering shaft 31 . In the case of this embodiment, the steering changeover switch 52 is composed of a swingable lever. The steering changeover switch 52 can swing around a base end provided on the steering shaft 31 side as a fulcrum. A base end portion of the steering changeover switch 52 is provided inside the column cover 179 . The steering switch 52 protrudes to one side (left) of the column cover 179 .

The correction switch 53 is arranged on the other side (right side) of the steering shaft 31 . More specifically, the correction switch 53 is arranged to the right and rear (diagonally right rear) of the steering shaft 31 . The correction switch 53 is arranged to the right and rear (diagonally right rear) of the column cover 179 in terms of positional relationship with the column cover 179 . The correction switch 53 is arranged on the rear right side of the mounting surface 178f of the panel cover 178 in terms of the positional relationship with the mounting surface 178f. By arranging the correction switch 53 at the rear portion of the inclined mounting surface 178f, a long distance between the correction switch 53 and the steering handle 30 can be ensured. As a result, unintended operation of the correction switch 53 and steering of the steering wheel 30 can be prevented more reliably.

As described above, the setting switch 51 , the steering changeover switch 52 and the correction switch 53 are arranged around the steering shaft 31 . In other words, the setting switch 51 , the steering switch 52 , and the correction switch 53 are concentrated around the steering shaft 31 . Therefore, the driver can grasp the position of each switch at a glance. In addition, the driver can operate each switch while seated on the driver's seat 10 without changing his/her posture. Therefore, operability is improved, and erroneous operations can be prevented. Moreover, the harness (wiring) routed from each switch can be shortened.

Incidentally, regarding the arrangement of the switches described above, the left and right sides may be interchanged. That is, one side may be the left side and the other side may be the right side, or one side may be the right side and the other side may be the left side. Specifically, for example, the setting switch 51 and the steering changeover switch 52 may be arranged on the right side of the steering shaft 31 and the correction switch 53 may be arranged on the left side of the steering shaft 31 .

As shown in FIG. 1 , the tractor 1 has a plurality of control devices 60 . The plurality of control devices 60 are devices that perform travel system control, work system control, vehicle body position calculation, and the like in the tractor 1 . The plurality of control devices 60 are a first control device 60A, a second control device 60B and a third control device 60C.
The first control device 60A receives the satellite signal (received information) received by the receiver 41 and the measurement information (acceleration, angular velocity, etc.) measured by the inertial measurement device 42, and determines the position of the vehicle body based on the received information and the measurement information. Ask for For example, when the correction amount by the correction switch 53 is zero, i.e., when correction of the vehicle body position by the correction switch 53 is not instructed, the first control device 60A calculates the calculated vehicle body position using the received information and the measurement information. Without correcting the position W1, the calculated vehicle body position W1 is determined as the vehicle body position used during automatic steering. On the other hand, when correction of the vehicle body position by the correction switch 53 is commanded, the first control device 60A corrects the vehicle body position based on either the number of operations of the correction switch 53 or the operation amount (displacement amount) of the correction switch 53. A correction amount is set, and a corrected vehicle body position W3 obtained by correcting the calculated vehicle body position W1 with the correction amount is determined as a vehicle body position to be used during automatic steering.

The first control device 60A sets a control signal based on the vehicle body position (calculated vehicle body position W1, corrected vehicle body position W3) and the planned travel line L2, and outputs the control signal to the second control device 60B. The second control device 60B has an automatic steering control section 200. As shown in FIG. The automatic steering control unit 200 is composed of an electrical/electronic circuit provided in the second control device 60B, a program stored in a CPU, and the like. The automatic steering control unit 200 controls the steering motor 38 of the automatic steering mechanism 37 so that the vehicle body 3 travels along the scheduled travel line L2 based on the control signal output from the first control device 60A.

As shown in FIG. 7, the automatic steering control unit 200 maintains the rotation angle of the rotation shaft of the steering motor 38 when the deviation between the vehicle body position and the planned travel line L2 is less than the threshold. When the deviation between the vehicle body position and the planned travel line L2 is greater than or equal to the threshold and the tractor 1 is positioned on the left side of the planned travel line L2, the automatic steering control unit 200 controls the steering direction of the tractor 1 to the right. The rotating shaft of the steering motor 38 is rotated so as to be in the direction. When the deviation between the vehicle body position and the planned travel line L2 is greater than or equal to the threshold and the tractor 1 is positioned on the right side of the planned travel line L2, the automatic steering control unit 200 controls the steering direction of the tractor 1 to the left. The rotating shaft of the steering motor 38 is rotated so as to be in the direction. In the above-described embodiment, the steering angle of the steering device 11 is changed based on the deviation between the vehicle body position and the planned travel line L2. If the orientation (vehicle orientation) F1 (traveling direction) is different, that is, if the angle θg of the vehicle orientation F1 with respect to the planned travel line L2 is equal to or greater than the threshold, the automatic steering control unit 200 controls the angle θg to be zero (vehicle orientation). The steering angle may be set so that F1 coincides with the direction of the planned travel line L2. Further, the automatic steering control unit 200 sets the final steering angle in automatic steering based on the steering angle obtained based on the deviation (positional deviation) and the steering angle obtained based on the bearing (bearing deviation). may The setting of the steering angle in the automatic steering in the embodiment described above is an example, and is not limited.

As described above, the control device 60 can automatically steer the tractor 1 (the vehicle body 3).
60 C of 3rd control apparatuses perform various control regarding the tractor 1. FIG. The third control device 60C can perform manual elevation control, auto-up control, double speed control, and the like. The manual elevation control is a control for raising and lowering the elevation device 8 based on the operation of the elevation switch 101 connected to the third control device 60C. Specifically, the lift switch 101 is provided around the driver's seat 10 and is a three-position selector switch. When the lift switch 101 is switched from the neutral position to one side, a lift signal for lifting the lift device 8 (lift arm 8a) is input to the third control device 60C. Further, when the lift switch 101 is switched from the neutral position to the other position, a lowering signal for lowering the lifting device 8 (lift arm 8a) is input to the third control device 60C. The third control device 60C raises the lifting device 8 by outputting a control signal to the control valve 29 when the rising signal is obtained, and outputs a control signal to the control valve 29 when obtaining the falling signal to move the lifting device 8. lower. That is, the third control device 60 can perform manual elevation control for raising and lowering the elevation device 8 according to the manual operation of the elevation switch 101 .

In the auto-up control, when the tractor 1 (vehicle body 3) moves backward, the lifting device 8 is automatically operated to raise the working device 2. As shown in FIG. Specifically, the control device 60, such as the control device 60C, is connected to a reverse motion detection device 102 that detects reverse motion. The reverse detection device 102 is a sensor that detects rotation of the front axle 21F, a sensor that detects rotation of the rear axle 21R, a sensor that detects the switching position of the shuttle lever 181, and the like. That is, the reverse detection device 102 detects the tractor 1 (the vehicle body 3 ) backward. When the reverse movement detection device 102 detects that the tractor 1 (vehicle body 3) is moving backward, the third control device 60C outputs a control signal to the control valve 29 to perform auto-up control to automatically raise the lifting device 8. It should be noted that the backward detection device 102 described above is an example and is not limited.

Further, in the double-speed control, when the steering angle of the steering device 11 is a predetermined value or more, for example, when the steering angle corresponds to turning, by automatically changing the connection of the first clutch 17 and the second clutch 18, the front wheels can be rotated. Make the rotation speed of 7F faster than the rotation speed of the rear wheels. Specifically, a steering angle detection device 205 that detects the steering angle of the steering device 11 is connected to the control device 60 such as the control device 60C. When the steering angle detected by the steering angle detection device 205 is equal to or greater than the steering angle corresponding to turning, the control device 60C outputs a control signal to the first operating valve 25 and the second operating valve 26, so that the first clutch 17 in the connected state and the second clutch 18 in the disengaged state, the rotational speed of the front wheels 7F is made faster than the rotational speed of the rear wheels.

As described above, the control device 60C can perform controls related to the tractor 1, such as manual elevation control, auto-up control, and double speed control.
The work vehicle is provided with a vehicle speed detection device for detecting the running speed (vehicle speed) of the tractor 1 (body 3). The running speed (vehicle speed) is obtained by converting the number of revolutions of a rotating shaft provided in the vehicle body 3 . As shown in FIG. 1, the vehicle speed detection device has a rotation detection device 43a that detects the rotation speed of the front wheel drive shaft 23 from the transmission 5 to the front wheels 7F. The rotation detection device 43a is provided on the side of the gear 44 that meshes with the gear 17a of the first clutch 17 and rotates together with the front transmission shaft 22. By detecting the rotation speed of the gear 44, the rotation speed of the front wheel drive shaft 23 is detected. That is, the rotation speed of the front transmission shaft 22 is detected.

The rotation detection device 43a detects the rotation speed (first rotation speed) of the front transmission shaft 22 when the first clutch 17 is disengaged and the second clutch 18 is engaged (4WD constant speed state), i. ) and the number of rotations (second number of rotations) of the front transmission shaft 22 when the first clutch 17 is engaged and the second clutch 18 is disengaged (4WD acceleration state), that is, when the double speed device is operating. To detect. The difference (acceleration amount) between the first rotation speed in the 4WD constant speed state and the second rotation speed in the 4WD acceleration state changes depending on the gear ratio in the first clutch 17 and the second clutch 18. do. In this embodiment, the second number of revolutions is twice as large as the first number of revolutions.

The vehicle speed detection device has a first calculation section 701 and a second calculation section 702 . The first arithmetic unit 701 and the second arithmetic unit 702 are composed of electric/electronic circuits provided in the second control device 60B, programs stored in the CPU and the like.
The first calculation unit 701 calculates the traveling speed of the vehicle body 3 from the first rotation speed. For example, the first calculation unit 701 obtains the traveling speed by incorporating the conversion coefficient K1 for converting the rotation speed into the speed into the first rotation speed. Specifically, the conversion coefficient K1 is a conversion coefficient K1 for converting the rotation speed of the front transmission shaft 22 into the running speed based on the relationship between the outer diameter of the rear wheel 7R and the rotation speed of the front transmission shaft 22. The calculation unit 701 stores. When the first rotation speed is "RV1" and the running speed is "VB1", the first calculating unit 701 calculates the running speed in the 4WD constant speed state by VB1=RV1×K1, that is, the double speed device is operated. Calculate the running speed VB1 when the vehicle is not running.

A second calculation unit 702 calculates the running speed of the vehicle body 3 from the second rotation speed. The second calculation unit 702 obtains a subtracted rotational speed by subtracting the increased rotational speed of the front transmission shaft 22 during operation of the double-speed device from the second rotational speed, and adds the conversion factor K1 to the obtained subtracted rotational speed. By doing so, the running speed is obtained. The second calculation unit 702 calculates the 4WD acceleration state by VB2=(RV2−UV1)×K1, where the second rotation speed is “RV2”, the increased rotation speed is “UV1”, and the running speed is “VB2”. The running speed at that time, that is, the running speed VB2 when the double speed device is operating is obtained. As described above, when the double-speed device is in operation, it doubles compared to when the double-speed device is not in operation. RV2/2). Further, since the increased rotational speed UV1 is the amount of increase between the 4WD constant speed state and the 4WD double speed state at the second rotational speed, the second calculation unit 702 has a formula or the like for converting the increased amount in advance. good too.

As described above, the vehicle speed detection device can determine the running speed when the speed doubler is operating and the running speed when the speed doubler is not operating.
The display device 45 displays the running speed VB1 calculated by the first calculation unit 701 when the speed doubling device is not in operation, and displays the traveling speed VB1 calculated by the second calculation unit 702 when the speed doubling device is in operation. Display the running speed VB2.

As shown in FIG. 6, the display device 45 has a display section 46 that displays various information. The display unit 46 includes a fixed display unit 46A that displays warnings and the like, and a variable display unit 46B that can change displayed information. The fixed display section 46A has a panel on which graphics such as warnings are shown, and an irradiation section such as an LED that irradiates the graphics on the panel with a light source. Also, the variable display section 46B is composed of an organic EL panel, a liquid crystal panel, or the like, and displays various information related to the operation (running) of the tractor 1 and the like.

9A shows the operation screen M1 of the tractor 1. FIG. The operation screen M1 is a screen displayed on the variable display section 46B when the setting switch 51 is OFF, that is, when the setting mode is disabled.
The display device 45, that is, the operation screen M1 has an operation display section 61 that shows operation information. The operation display unit 61 includes a rotation display unit 62 that displays the rotation speed of the engine 4 (motor rotation speed) as operation information. The rotary display section 62 includes a level display section 63 . The level display portion 63 is a portion that displays the engine speed in stages. For example, the level display portion 63 includes a scale portion 65 and an indicator portion 80 . The scale portion 65 has, for example, a first line 65A and a plurality of second lines 65B allocated at predetermined intervals along the first line 65A. Also, the scale portion 65 has a first line 65A and a third line 65C spaced apart at a predetermined interval. The first line 65A and the third line 65C are formed, for example, in a semicircular shape, with one end side (for example, left side) having a minimum value and the other end side (for example, right side) having a maximum value. .

The indicator portion 80 is a bar whose length changes according to the number of revolutions of the engine. The indicator part 80 is positioned, for example, between the first line 65A and the third line 65C, and when the engine speed value is the minimum value of zero, the first line 65A and the third line 65C When it is located on the one end side (left side) and has the shortest length and the value of the motor revolution speed is the maximum value, from the one end side (left side) of the first line 65A and the third line 65C to the first line 65A and the third line 65C. It extends to the other end side (right side) of the third line 65C and is the longest. The rotating display portion 62 includes a numeric display portion 64 . A numeric display unit 64 displays the number of revolutions of the engine in numbers. For example, the rotating display portion 62 is arranged inside the semicircles of the first line 65A and the third line 65C.

Therefore, according to the operation display section 61 , the motor rotation speed such as the engine rotation speed can be displayed in stages by the level display section 63 and numerically by the rotation display section 62 .
The operation screen M1 has an icon display portion 67 that displays a plurality of icon portions 66. FIG. The icon display portion 67 is a portion where various information is indicated by the icon portion 66 . That is, the settings related to running such as automatic steering, for example, the setting state set in the setting mode are displayed in the icon portion 66 . The icon display portion 67 is located at a different position from the driving display portion 61, and is arranged, for example, in the upper portion of the driving screen M1.

The plurality of icon portions 66 includes a first icon portion 66A, a second icon portion 66B, a third icon portion 66C, a fourth icon portion 66D, a fifth icon portion 66E, a sixth icon portion 66F, a seventh icon portion 66G, a 8 icon portion 66H. Note that the operation screen M1 does not need to have all of the plurality of icon portions 66 (66A, 66B, 66C, 66D, 66E, 66F, 66G, 66H), and is not limited to the embodiment described above.

The first icon portion 66A is displayed when a warning occurs. The second icon portion 66B is displayed when the starting point P10 of the driving reference line L1 is set. The third icon portion 66C is displayed when the end point P11 of the driving reference line L1 is set.
The fourth icon portion 66D is displayed when the conditions for automatic steering are met. For example, the fourth icon portion 66D is displayed when the setting mode is enabled, the setting of the driving reference line L1 is completed, and the planned driving line L2 can be set.

The fifth icon portion (double speed display portion) 66E is displayed when the lifting device 8 is in the lifting state. The sixth icon portion 66F is displayed when the vehicle is in the 4WD acceleration state, that is, when the double speed device is activated, and is not displayed when the double speed device is not activated. The color of the seventh icon portion 66G changes according to the reception sensitivity of the reception signal of the reception device 41 .
The display of the eighth icon portion 66H changes according to the automatic steering conditions. The eighth icon portion 66H is displayed when the automatic steering cannot be performed for some reason, for example, when the setting mode is disabled or when the receiving signal reception sensitivity of the receiving device 41 is low and the vehicle body position cannot be detected. is not set, it turns gray to indicate that automatic steering cannot be performed. The eighth icon portion 66H can detect the position of the vehicle body when the setting mode is valid and the reception sensitivity of the reception signal of the reception device 41 is equal to or higher than a predetermined value, for example, when the automatic steering becomes possible for some reason. If the driving reference line L1 has been set, the green color indicates that automatic steering can be performed. Note that the display form in the eighth icon portion 66H is not limited to the display form described above.

9B shows the operation screen M2 of the tractor 1. FIG. The operation screen M2 is a screen displayed on the variable display section 46B when the setting switch 51 is ON, that is, when the setting mode is valid. The operation screen M2 also includes an operation display portion 61 and an icon display portion 67, like the operation screen M1. In other words, the driving screen M2 is a screen capable of displaying at least the same information as the driving screen M1 regarding the driving information. Since the operation display portion 61 and the icon display portion 67 are the same as those of the operation screen M1, description thereof is omitted.

When the setting mode is changed from disabled to enabled, the display device 45 changes the display state of the operation display section 61 of the operation screen M2 to a display form different from the display state of the operation display section 61 of the operation screen M1. . That is, when the setting mode is valid, the display device 45 makes the display state of the operation display section 61 when the setting mode is valid different from the display form of the operation display section 61 when the setting mode is invalid.
The display device 45 sets the color (coloration) indicating the operation display portion 61 on the operation screen M2 to a color different from the color (coloration) indicating the operation display portion 61 on the operation screen M1. Specifically, the display device 45 sets the color of the scale portion 65 of the level display portion 63 in the operation screen M2, that is, the colors of the first line 65A, the second line 65B, and the third line 65C to the same color as that of the operation screen M1. However, the color of the indicator portion 80 of the operation screen M2 is set to a color different from that of the operation screen M1. That is, when the setting mode is enabled, the color of the index portion 80 is different from the color of the index portion 80 when the setting mode is disabled.

Further, the display device 45 sets the color of the number display portion 64 in the operation screen M2, that is, the color of the number indicating the number of rotations of the prime mover, to a color different from that of the operation screen M1. That is, when the setting mode is enabled, the color of the number display portion 64 is different from the color of the number display portion 64 when the setting mode is disabled.
The driving display unit 61 includes a speed display unit 710 that displays running speeds VB1 and VB2 as driving information. The speed display unit 710 displays the running speed by, for example, a numerical value, a level gauge, or the like. The speed display unit 710 displays the running speed VB1 calculated by the first calculation unit 701 when the double speed device is not in operation (when the double speed control is not performed). The speed display unit 710 displays the travel speed VB2 calculated by the second calculation unit 702 when the double speed device is activated (when the double speed control is performed).

That is, the fifth icon portion (double speed display portion) 66E and the speed display portion 710 can be displayed on the operation screens M1 and M2. Therefore, the running speed of the speed display portion 710 when the fifth icon portion (double speed display portion) 66E is not displayed is the running speed VB1 when not running at the double speed, and the fifth icon portion (double speed display portion) ) 66E is displayed on the speed display unit 710, it can be easily understood that the running speed is the running speed VB2 when running at double speed.

The work vehicle 1 is provided with a steering handle 30 and a travel device including front and rear wheels, and can travel by either manual steering by the steering handle 30 or automatic steering by the steering handle 30 based on the travel reference line L1. a vehicle body 3, a transmission 5 including a speed doubler that makes the rotational speed of the front wheels 7F faster than the rotational speed of the rear wheels 7R when the steering angle of the steering handle 30 is greater than or equal to a predetermined value, and the transmission from the transmission 5 to the front wheels 7F. and a rotation detection device 43a for detecting the rotation speed of the front wheel drive shaft 23, and the first rotation speed, which is the rotation speed of the front wheel drive shaft 23 detected by the rotation detection device 43a when the speed doubler is not operating. The traveling speed of the vehicle body 3 is calculated from the first calculating section 701 that calculates the traveling speed and the second rotation speed that is the rotation speed of the front wheel drive shaft 23 detected by the rotation detecting device 43a when the speed doubler is operating. and a second computing unit 702 . According to this, when the double speed device is not operated, the first rotation speed calculated by the first calculation unit 701 can be obtained, and when the double speed device is operated, the second speed calculation unit 702 is used. A second rotational speed can be determined. That is, in the work vehicle 1 capable of manual steering and automatic steering, a speed doubler is provided, and a rotation detection device 43a for detecting the running speed is provided on the drive shaft (front wheel drive shaft 23) on the front wheel 7F side. Even in this case, the running speed can be properly detected. Further, in the work vehicle 1, the rotation detection device 43a can be provided in an empty space on the front wheel 7F side, and the mounting portion of the rotation detection device 43a can be made compact.

The work vehicle 1 displays the running speed of the vehicle body 3 calculated by the first calculation unit 701 when the speed doubling device is not in operation, and calculates it by the second calculation unit 702 when the speed doubling device is in operation. A display device 45 for displaying the running speed of the vehicle body 3 is provided. According to this, by looking at the display device 45, it is possible to easily grasp the traveling speed both when the double speed device is operating and when the double speed device is not operating.

The first calculation unit 701 obtains the traveling speed of the vehicle body 3 by incorporating the conversion coefficient for converting the rotation speed into the speed in the first rotation speed, and the second calculation unit 702 calculates the speed doubler in the second rotation speed. The traveling speed of the vehicle body 3 is obtained by calculating the division number of rotations by dividing the increased number of rotations of the front wheel drive shaft 23 at the time of operation, and incorporating the conversion factor into the obtained division number of rotations. According to this, by using the conversion factor, the traveling speed can be easily obtained from the first rotation speed of the front wheel drive shaft 23, and by using both the conversion factor and the division rotation speed, the speed of the front wheel drive shaft 23 can be easily obtained. The traveling speed can be obtained from the second rotation speed.

The work vehicle 1 includes a steering changeover switch 52 for switching between starting and ending automatic steering. to start. According to this, by operating the steering selector switch 52, manual steering can be easily switched to automatic steering.
The work vehicle 1 includes a positioning device 40 capable of detecting the position of the vehicle body 3, and a reference line setting switch for setting the position of the vehicle body 3 detected by the positioning device 40 to the starting position and the ending position of the traveling reference line L1. I have.

According to this, the driving reference line L1 can be easily set by operating the reference line setting switch.
It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

1: Work vehicle (tractor)
3: Vehicle body 5: Transmission device 7: Running device 7F: Front wheel 7R: Rear wheel 30: Steering handle 40: Positioning device 43a: Rotation detection device 45: Display device 60: Control device 701: First calculation unit 702: Second calculation Department

Claims (4)

steering handle and
a vehicle body provided with a traveling device including front wheels and rear wheels, and capable of traveling by either manual steering using the steering handle or automatic steering using the steering handle based on a traveling reference line;
a transmission including a speed doubler that makes the rotational speed of the front wheels higher than the rotational speed of the rear wheels when the steering angle of the steering handle is greater than or equal to a predetermined value;
a rotation detection device for detecting the number of rotations of a front wheel drive shaft extending from the transmission to the front wheels;
By multiplying the first rotation speed, which is the rotation speed of the front wheel drive shaft detected by the rotation detection device when the double speed device is not operating, by a conversion coefficient for converting the rotation speed to speed, the vehicle body travels. a first calculation unit that calculates speed;
The number of rotations of the front wheel drive shaft detected by the rotation detection device when the speed doubling device is in operation is calculated from the number of rotations of the front wheel drive shaft when the speed doubling device is in operation and when the speed doubling device is in operation. a second calculation unit that calculates the traveling speed of the vehicle body by obtaining a subtraction rotation speed obtained by subtracting the increase rotation speed, which is an increase amount, and multiplying the subtraction rotation speed by the conversion coefficient;
When the speed doubling device is not operating, the running speed of the vehicle body calculated by the first calculation unit is displayed, and when the speed doubling device is operating, the vehicle body calculated by the second calculation unit a display device for displaying the running speed of the
A work vehicle equipped with 2. The second calculation unit has a formula for calculating the increased number of revolutions based on the second number of revolutions, and obtains the subtracted number of revolutions based on the second number of revolutions and the formula. Work vehicle described in . a steering selector switch for switching between starting and ending the automatic steering ;
an automatic steering control unit that starts automatic steering of the steering handle when the steering changeover switch switches the start of the automatic steering;
The work vehicle according to claim 1 or 2, comprising : a positioning device capable of detecting the position of the vehicle body;
a reference line setting switch for setting the position of the vehicle body detected by the positioning device to the start position and end position of the travel reference line;
The work vehicle according to any one of claims 1 to 3, comprising:

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