JP6700167B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as a tractor and a rice transplanter, and more particularly, to automatic control of a lifting device for lifting a work machine.

  2. Description of the Related Art Conventionally, there has been proposed a work vehicle provided with automatic control of a working machine at the time of turning, which is operated when turning at the end of a field in work such as tilling and planting performed in the field (Patent Document 1). In this work vehicle, when the machine reaches the end of the field and the front wheels are steered, the distance sensor starts integrating the travel distance of the machine and the working device is raised to reach the set distance of the machine. Then, the working device is lowered.

Japanese Patent No. 4605622

  However, the device described in Patent Document 1 lowers the working device by determining whether or not the position of the machine body has reached the position at which work should be restarted based on the traveling distance of the machine body, and therefore the work device is lowered, so that the vehicle turns in the field. In a working vehicle that has a front wheel speedup control that increases the rotation speed of the front wheel with respect to the rear wheel, and an automatic braking control that brakes only the rear wheel that is inside the turn, whether these controls are executed or not. As a result, the radius of curvature of the traveling body changes when it turns, which lowers the accuracy of the position prediction of the body.

  Therefore, the present invention is a work vehicle that calculates the position of the traveling machine body when turning at the field edge, and starts descending the working machine when the working machine lowering start region based on the position at the start of turning of the traveling machine body is reached. , The headland width from the edge is set to a predetermined value regardless of whether control is performed to change the number of revolutions of the traveling parts such as front wheels and rear wheels that affect the radius of curvature when the traveling vehicle turns. It is an object of the present invention to provide a work vehicle capable of performing work in a wide range with high accuracy.

The present invention steers a traveling machine body (2) supported by a pair of left and right front wheels (5) and a pair of left and right traveling parts (6) arranged behind the front wheels, and the traveling machine body (2). A working vehicle (1) comprising a steering section (12) and a lifting device (16) for lifting and lowering a working machine (3),
A working machine descending start region is set with reference to the position of the traveling machine body (2) at the start of turning, and the radius of curvature of the steering section (12) and the traveling distance of the front wheel (5) and the traveling section (6). The position of the traveling machine body (2) is calculated based on the above, and when the traveling machine body (2) reaches the working machine lowering start region, the elevating device (16) starts lowering of the working machine (3). Turning control,
Front wheel acceleration control that drives the peripheral speed of the front wheels (5) to increase with respect to the peripheral speed of the traveling unit (6) when the traveling machine body (2) turns, and the inside of the turning when the traveling machine body (2) turns. And at least one of automatic braking control for braking the traveling section (6)
In the turning control, when the front wheel acceleration control or the automatic braking control is being executed, the radius of curvature (r) is calculated by the radius of curvature based on the executed control.
It is characterized by

For example, referring to FIGS. 2, 3, 6, 7, 7, 8, 9, 10, 13, 14, and 19, power is applied to the front wheel (5) and the traveling section (6). A drive state switching means capable of selecting one of a four-wheel drive state for transmitting and a two-wheel drive state for transmitting power only to the traveling section (6);
Transmission means capable of adjusting the reduction ratio of the front wheels (5) and the traveling section (6),
The turning control starts the descent of the work machine on condition that the four-wheel drive state is selected and the reduction ratio of the traveling unit (6) is adjusted to be a reduction ratio larger than a predetermined reduction ratio. Set the area.

For example, referring to FIG. 4, FIG. 7, FIG. 8, FIG. 10, FIG. 13, FIG. 14 and FIG. 19, the ascending height adjusting means capable of adjusting the upper limit height when ascending the working machine (3) ( 32),
The turning control sets the working machine lowering start region based on the upper limit height of the working machine (3) and the traveling speed of the traveling machine body (2).

For example, referring to FIG. 2, FIG. 7, FIG. 8, FIG. 10, FIG. 13, FIG. 14 and FIG. 19, a lowering speed setting means (29) for setting a lowering speed when lowering the working machine (3) is provided. Prepare,
The turning control sets the working machine lowering start region based on the lowering speed of the working machine (3) and the traveling speed of the traveling machine body (2).

  For example, referring to FIG. 4, FIG. 7, FIG. 8, FIG. 10, FIG. 13, FIG. 14 and FIG. 19, it comprises a descent start area adjusting means (33) for adjusting the working machine descent start area.

  The reference numerals in parentheses above are for comparison with the drawings, but do not limit the configuration of the present invention.

  According to the first aspect of the present invention, the control means sets the working machine descent start region on a coordinate system whose origin is the position at which the traveling machine body starts to turn, and the traveling operation of the traveling machine body and the traveling distance and the front wheels. The position of the traveling machine body is calculated based on the radius of curvature when the traveling machine body makes a turn, which is calculated based on whether or not the speed increasing control and the automatic braking control are being executed, and the working machine in the state where the traveling machine body completes the turning. Since the working machine is started to descend when it reaches the descending start region, the accuracy of calculating the position of the traveling machine body is improved, and the headland width from the ridge can be aligned with a predetermined width with high accuracy.

  According to the second aspect of the present invention, the control means is selected such that the four-wheel drive state is selected and the reduction ratio of the traveling portion is adjusted to be a greater reduction ratio than a predetermined reduction ratio. Since the work equipment descent start area is set, there is no risk of the work equipment automatically descending when the gear ratio is set to a small reduction ratio of the traveling part that is not intended for tilling work in the field, and the operator does not intend Not possible to prevent the work machine from descending.

  According to the third aspect of the present invention, the control means sets the working machine lowering start region based on the upper limit height of the working machine and the traveling speed of the traveling machine body, so that the working machine starts landing after starting to descend. The distance traveled by the traveling body can be predicted with high accuracy, and the headland width from the ridge can be aligned with a predetermined width with high accuracy.

  According to the present invention of claim 4, the control means sets the working machine lowering start region based on the lowering speed of the working machine and the traveling speed of the traveling machine body. Therefore, from the start of the lowering of the working machine to the landing. In addition, the distance traveled by the traveling body can be predicted with high accuracy, and the headland width from the ridge can be aligned with a predetermined width with high accuracy.

  According to the fifth aspect of the present invention, since the work vehicle is provided with the descent start area adjusting means, when an error occurs in the descent start line due to slip of the front wheels or the traveling part, or in a field that is not rectangular, for example, a trapezoid. Even when cultivating work in a field such as the field, the headland width from the ridge can be aligned with a predetermined width with high accuracy.

The side view which shows the tractor which concerns on this Embodiment. The perspective view which shows the rear part of a driving part. The perspective view which shows a side panel. The top view which shows a side panel. The perspective view which shows the front part of a driving part. The perspective view which shows a front panel. The block diagram of a control part. The flowchart which shows the main routine of auto-down control. The flowchart of a control state process. The flowchart of a body information acquisition process. Flow chart of aircraft angle processing. The flowchart of an angle calculation. Flow chart of position calculation. The flowchart of a position flag process. The flowchart of a position determination process. The flow figure of descent start processing. The flowchart of an automatic end process. FIG. 4 is a diagram showing the contents displayed on the liquid crystal display device, (a) is a diagram showing an auto-down canceling state display, (b) is a diagram showing a display when the auto-down is being executed, (c) is an auto-down control The figure showing the display when the descent of the rotary cultivator is stopped by, (d) is the figure showing the display when the descent of the rotary cultivator by the automatic down control is paused, and (e) is the automatic down The figure which shows the display when the rotary tiller is descending by control, (f) the figure which shows the automatic down control position notification display, (g) the figure which shows the automatic down control position cancellation display, (h) the machine Enlarged view showing the display when the angle is within the first angle range, (i) is an enlarged view showing the display when the aircraft angle is within the second angle range, (j) is the aircraft angle is the third angle range (M) is an enlarged view showing the display when the aircraft angle is within the turning completion angle range and the Y coordinate of the traveling aircraft is outside the predetermined range. (m) is the aircraft angle Is an enlarged view showing the display when the angle is within the fourth angle range, (n) is an enlarged view showing the display when the aircraft angle is within the fifth angle range, and (p) is the aircraft angle within the turning completion angle range FIG. 7 is an enlarged view showing a display when the Y coordinate of the traveling body is within a predetermined range. Schematic which shows the traveling route of a tractor.

<Overall structure>
Hereinafter, the present embodiment will be described with reference to the drawings. As shown in FIG. 1, a tractor 1 as a work vehicle according to the present embodiment has a traveling machine body 2 and a rotary 3b that rotates, and serves as a working machine that is vertically movable to a rear portion of the traveling machine body 2. And a rotary cultivator 3. The traveling machine body 2 has a control unit 52 shown in FIG. 7 for controlling input/output of each electric signal, a front wheel 5 and a rear wheel 6 as a traveling unit. The front wheels 5 and the rear wheels 6 are respectively arranged on the left and right and provided in pairs, and the front body 5 is steered to the left and right to steer the traveling machine body 2. Further, the traveling machine body 2 includes a machine body frame 7 supported by the front wheels 5 and the rear wheels 6, and a driving unit 10 having a driver seat 23 on which an operator rides. In the present embodiment, unless otherwise specified, the front direction facing the operator seated on the driver's seat 23 of the tractor 1 placed on a horizontal plane is the front, which is the direction of the traveling machine body 2, and the front-back direction is based on this. Define the left-right direction. On the output side of the control unit 52, a notification buzzer 53 that can notify the operator of various kinds of information by emitting a sound is provided, and operates by an output signal from the control unit 52.

<Power transmission structure>
The machine frame 7 includes an engine (not shown) that generates power for driving the front wheels 5 and the rear wheels 6, an engine room 9 in which the engine is housed, and a mission (not shown) arranged between the left and right rear wheels 6. A case is provided.

  A traveling transmission (not shown) that shifts the power of the engine is housed inside the transmission case. The traveling transmission includes a main transmission mechanism (not shown) as a transmission that shifts the power of the engine in multiple stages and a main transmission. A sub-transmission mechanism (not shown) that serves as a transmission unit that further shifts the power that has been shifted by the mechanism in multiple stages, and a PTO transmission mechanism that shifts the power to the PTO shaft (not shown) are incorporated. The rotation of the PTO shaft is transmitted to the rotary cultivator 3, and the rotary 3b rotates about the rotary shaft 3a to cultivate the field.

  The inside of the mission case is filled with lubricating oil, and this lubricating oil is supplied to a hydraulic pump (not shown) driven by the power of the engine, and the hydraulic pressure generated by the hydraulic pump is rotated by operating the lift arm valve 20 shown in FIG. It is transmitted to a lift arm cylinder (not shown) that raises and lowers the cultivator 3.

  Power that has passed through the main transmission mechanism and the auxiliary transmission mechanism is distributed to the left and right rear wheels 6 by a rear wheel drive shaft (not shown) via a rear wheel differential mechanism (not shown), and a front wheel transmission mechanism (not shown) and a front wheel drive shaft (not shown) are provided. Is distributed to the left and right front wheels 5 via a front wheel differential mechanism (not shown), and when the traveling vehicle body 2 turns left and right by turning the front wheels 5, a difference in rotation speed between the inner wheel and the outer wheel is allowed, thereby smoothing It is configured to be capable of various running.

  The rear wheel differential mechanism transmits power from the rear wheel drive shaft to the left and right rear wheels 6 via a pair of left and right brake mechanisms (not shown) capable of independently braking the left and right rear wheels 6. The number of rotations per unit time of the rear wheel drive shaft and one of the left and right rear wheels 6 is independently detected by the vehicle speed sensor 11, and the rear wheel drive shaft and one of the left and right rear wheels 6 per unit time. The vehicle speed as the traveling speed of the traveling machine body 2 is calculated based on the number of revolutions. Here, the vehicle speed is a moving distance per unit time of the machine body reference point 2a, which is the center point of the left and right rear wheels 6 on the rotation axis of the rear wheels 6, as shown in FIG. The information on the vehicle speed at the calculated time point is transmitted to the control unit 52 by an electric signal. Further, the control unit 52 integrates the vehicle speed with respect to time to obtain the moving distance of the machine body reference point 2a, that is, the traveling distance of the traveling machine body 2.

  The front wheel speed change mechanism is provided with a friction multi-plate hydraulic clutch (not shown) as a drive state switching means, and when the hydraulic clutch is connected or disconnected, the traveling machine body 2 changes the average peripheral speed of the left and right front wheels 5 to that of the left and right rear wheels 6. The front wheel double speed ON 4WD mode in which the front wheel double speed control is executed as the front wheel speed-up control for increasing the average peripheral speed, and the average peripheral speed of the left and right front wheels 5 is changed to the average peripheral speed of the left and right rear wheels 6. On the other hand, a front wheel double speed OFF four-wheel drive mode in which the vehicle is driven at a substantially constant speed and a two-wheel drive mode in which power is not transmitted to the front wheels 5 are switchably provided.

<Steering device>
A steering device 12 as a steering section is arranged on the machine body frame 7. The steering device 12 includes a steering wheel 13 that is rotated by an operator to steer the front wheels 5, a steering column 14 that rotates together with the steering wheel 13 shown in FIG. 6, and a steering column 14 that extends left and right. A steering mechanism (not shown) that converts the rotation of the steering wheel into a substantially linear motion in the left-right direction, and a tie rod (not shown) that connects both ends of the steering mechanism and the left and right front wheels 5 are provided. When the operator turns the steering wheel 13, the steering column 14 turns, and the tie rods move left and right based on the turning angle and turning direction of the steering column 14 to steer the left and right front wheels 5.

  The steering device 12 is provided with stopper portions (not shown) for restricting rotation of the steering wheel 13 in one direction more than a predetermined amount in each of the left and right rotation directions. The maximum turning angle α1 in one direction from the neutral position of the steering wheel 13 in which the traveling machine body 2 travels substantially straight is configured to be substantially the same as the maximum turning angle in the other direction. When the steering wheel 13 is rotated from the neutral position by a predetermined angle α2 which is slightly smaller than the maximum rotation angle α1, the steering sensor 15 shown in FIG. 7 is turned on and the steering wheel 13 is rotated by α2 or more. Also, the turning direction of the steering wheel 13 is detected. When the turning angle of the steering wheel 13 is less than α2 from the neutral position, the steering sensor 15 is turned off, and it is detected that the turning angle of the steering wheel 13 is less than α2. Information about the on state or off state of the steering sensor 15 and the turning direction of the steering wheel 13 is transmitted to the control unit 52 by an electric signal.

<Lifting link mechanism>
In the rear part of the traveling machine body 2, an elevating link mechanism 16 as an elevating device for connecting the machine body frame 7 and the rotary cultivator 3 and elevating the rotary cultivator 3 is provided. The up-and-down link mechanism 16 includes a link bracket (not shown) that is provided to project from the rear portion of the traveling machine body 2, a single top link 17 that is pivotally supported up and down with respect to the link bracket and extends rearward, and a top. And a pair of left and right lower links 18 that are provided below the links and pivotally supported up and down with respect to the link brackets and extend rearward. The top link 17 and the rear end portions of the left and right lower links 18 are , The rotary cultivator 3 is pivotally supported up and down to form a three-point link mechanism. The left and right lower links 18 are suspended by lift arms (not shown) via lift rods (not shown) provided on the left and right, respectively. A front end of the lift arm is pivotally supported by a link bracket so that the lift arm can swing up and down. The lower link 18 swings up and down as the lift arm vertically swings as the lift arm cylinder expands and contracts. 3 moves up and down. The swing angle of the lift arm is detected by the lift arm sensor 21 shown in FIG. 7 provided on the lift arm and transmitted to the control unit 52 by an electric signal.

<Driving department>
Next, the operation unit 10 will be described with reference to FIG. On the left side of the driver's seat 23, an auxiliary shift lever 27, which is swingably supported to shift the auxiliary shift mechanism, is rotatably supported below the driver's seat 23 to lower the rotary cultivator 3. A working machine lowering speed adjusting knob 29 is provided as a lowering speed setting means capable of operating a lowering speed adjusting valve (not shown) for adjusting the speed. The sub-transmission lever 27 is provided so as to be operable in three shift positions of high speed, medium speed, and low speed. When the shift position of the sub-transmission lever 27 is in the high speed, the engine speed is set to The reduction ratio divided by the rotation speed of the wheel drive shaft is the smallest among the three stages, the reduction ratio is the highest in the low speed stage, and the reduction ratio in the middle speed stage is between the high speed stage and the low speed stage. ing. Further, when the operator rotates the working machine descending speed adjusting knob 29 clockwise, the descending speed adjusting valve is operated to decrease the descending speed of the rotary cultivator 3 and to rotate it counterclockwise. And the descending speed increases. The information on the shift position of the auxiliary shift lever 27 and the information on the rotating position of the work implement lowering speed adjustment knob 29 are transmitted to the control unit 52 by an electric signal.

<Side panel>
As shown in FIGS. 2, 3 and 4, a side panel 26 on which various operating tools and lamps are arranged is provided on the right side of the driver's seat 23. On the side panel 26, a main shift lever 30 that is swingably supported and shifts the main transmission mechanism, a position lever 31 that raises and lowers the rotary cultivator 3, and a lift that sets the maximum rising height of the rotary cultivator 3. A raising height volume 32 as height adjusting means and an automatic down timing volume 33 as descending start area adjusting means are arranged.

  The shift operation of the main shift mechanism by the main shift lever 30 can be performed independently of the shift operation of the sub shift mechanism by the sub shift lever 27, and the shift position and power of eight stages from the eighth gear to the first gear can be changed. It is provided so that it can be operated to a neutral position where it is not transmitted to the front wheels 5 and the rear wheels 6 and to an accelerator shift position where gears are automatically shifted from 8 to 4 speeds by operating an accelerator pedal (not shown). The eight speeds have the smallest reduction ratio by the main transmission mechanism, and the reduction ratio increases as the number of speeds decreases. The information on the shift position of the main shift lever 30 is transmitted to the control unit 52 by an electric signal.

  The position lever 31 is swingably supported in the front-back direction, and is configured to hold the swing position when the operator releases the operating hand. When the position lever 31 is rocked back and forth, the rotary cultivator 3 moves up and down to a height corresponding to the position where the position lever 31 is held. The information on the position where the position lever 31 is held is transmitted to the control unit 52 by an electric signal.

  The raising height volume 32 is rotatably supported, and a raising height adjusting position provided in a predetermined turning range and a hydraulic pressure take-out position are provided so as to be selectable depending on the turning position. .. When the rotating position of the raising height volume 32 is located at the raising height adjusting position, when the operator rotates the raising height volume 32 clockwise, the upper limit height when the rotary cultivator 3 moves up and down. Enlarge and rotate counterclockwise to reduce upper height limit. When the turning position of the raised height volume 32 is located at the hydraulic pressure take-out position, the traveling machine body 2 is in a state where the hydraulic pressure is transmitted from the hydraulic pressure take-out port (not shown) and the front loader or the like can be operated. At the same time, the hydraulic pressure to the lift cylinder is cut off, and the rotary cultivator 3 does not move up and down. The information on the rotational position of the raised height volume 32 is transmitted to the control unit 52 by an electric signal.

  The auto-down timing volume 33 is rotatably supported, and is provided so as to be changeable between an on position and an off position provided in a predetermined rotation range. When the turning position of the automatic down timing volume 33 is located at the ON position, the descent start timing of the rotary cultivator 3 can be adjusted in accordance with the turning position in the automatic down control described later. The information on the rotation position of the auto down timing volume 33 is transmitted to the control unit 52 by an electric signal. Further, the side panel 26 is provided with an automatic turn-on lamp 48. The automatic turn-on lamp 48 is turned off when the automatic down timing volume 33 is located in the off position, and is placed in the on position. Lights up or blinks when the auto-down permission condition described later is satisfied or not satisfied.

<Around the steering wheel>
As shown in FIG. 5, the steering wheel 13 is arranged in front of the driver's seat 23, and below the steering wheel 13, a brake pedal 25 and an accelerator pedal for operating the left and right brake mechanisms are arranged. Around the wheel 13, a starter switch 34, which is a main switch of the traveling machine body 2, a shuttle lever 35 for an operator to switch the traveling machine body 2 between forward and reverse, and a preset upper and lower limit height. A quick-up lever 36 for raising and lowering the rotary cultivator 3 is arranged.

  The shuttle lever 35 is operably provided at a forward position, a neutral position, and a reverse position. When the shuttle lever 35 is located at the forward position, the traveling machine body 2 moves forward, and when the shuttle lever 35 is located at the neutral position, the traveling machine body 2 moves. The traveling is stopped, and when the vehicle is in the reverse position, the traveling machine body 2 moves backward. Information on the operation position of the shuttle lever 35 is transmitted to the control unit 52 by an electric signal.

  The quick-up lever 36 is swingably supported between a raised position, a center position, and a lowered position, and is operated by an operator after raising the quick-up lever 36 to a raised position or lowered to a lowered position. A biasing member (not shown) is provided so as to return to the central position when is released. When the raising and lowering of the rotary cultivator 3 is stopped, a short raising operation of the quick-up lever 36 raises the rotary cultivator 3 to the upper limit height, and a short lowering operation causes the rotary cultivator 3 to reach the lower limit height. It descends to a height corresponding to the swing position of the position lever 31. The operation direction and operation time of the quick up lever 36 are transmitted to the control unit 52 by an electric signal.

<Front panel>
As shown in FIG. 6, a front panel 24 including various operating tools, a display device, and a lamp is arranged in front of the steering wheel 13. The front panel 24 includes a backup changeover switch 37 that switches the backup mode of the traveling vehicle 2 between an on state and an off state, and a swing up changeover switch 39 that switches between a turn up mode on state and an off state. When the traveling machine body 2 is in the backup mode ON state, the backup lamp 40 is lit, and the shuttle lever 35 is switched from the neutral position to the reverse position when the rotary tiller 3 is not positioned at the upper limit height. When done, the rotary tiller 3 is raised to the upper limit height. When the turning up mode is on, the turning up lamp 41 is turned on, and when the rotary cultivator 3 is not located at the upper limit height and the steering sensor 15 is switched from the off state to the on state, the rotary cultivator 3 is turned on. Rise to the maximum height. The switching information of the backup changeover switch 37 and the turning up changeover switch 39 is transmitted to the control unit 52 by an electric signal.

  Further, the front panel 24 includes a four-wheel drive changeover switch 42 for connecting/disconnecting the hydraulic clutch, and a turning double speed changeover switch 43 for connecting/disconnecting the hydraulic clutch and a braking operation by a brake mechanism. Every time the operator operates the four-wheel drive changeover switch 42, the traveling machine body 2 switches between each mode in which power is transmitted to the front wheels 5 and the two-wheel drive mode in which no power is transmitted to the front wheels 5 as a two-wheel drive state. The 4WD switching lamp 45 is turned on in each mode for transmitting power to the vehicle. Information on the switching operation by the four-wheel drive changeover switch 42 and the turning double speed changeover switch 43 is transmitted to the control unit 52 by an electric signal.

  Every time the four-wheel drive speed changeover switch 43 is operated while the four-wheel drive switching lamp 45 is lit, the traveling machine body 2 is in the four-wheel drive state and is in the front wheel double-speed off four-wheel drive mode, front wheel double-speed on four-wheel drive mode, and The auto brake mode switches. In the front wheel double speed ON 4WD mode, the turning double speed lamp 46 is turned on, and in the auto brake mode, the front wheel double speed control is executed and the control unit 52 automatically brakes the rear wheel 6 on the inside of the turning. The automatic brake control is executed and the automatic brake turning lamp 47 is turned on.

  The front panel 24 includes an Omakase changeover switch 49 capable of switching between a working mode for the traveling machine 2 to perform plowing work in the field and a traveling mode for traveling on the road outside the field, and the traveling machine 2 to be a working mode. An automatic switching lamp 50 for displaying which of the traveling modes is provided. Each time the operator operates the automatic selection switch 49, the working mode and the traveling mode of the traveling machine body 2 are alternately switched. When the traveling body 2 is switched from the work mode to the traveling mode, both the backup mode and the turning up mode are turned off, and when the front wheel double speed on 4WD mode or the automatic brake mode is set, the front wheel double speed off 4WD mode is set. When in the drive mode, the two-drive mode is maintained, lifting and lowering of the rotary cultivator 3 by the quick up lever 36 is restricted, and when the main shift lever 30 is in the accelerator shift position, the accelerator pedal is operated. Thus, the shift operation of the main transmission mechanism is enabled. When the traveling machine body 2 is switched from the traveling mode to the working mode, it is in any state of the backup mode, the turning up mode, the front wheel double speed ON 4WD mode, the automatic braking mode and the 2WD mode before the switching from the working mode to the traveling mode. Thus, the rotary cultivator 3 can be moved up and down by the quick up lever 36, and the shift operation of the main transmission mechanism by the operation of the accelerator pedal is restricted. The switching information of the work mode and the traveling mode by the automatic changeover switch 49 is transmitted to the control unit 52 by an electric signal.

<Liquid crystal display>
Further, the front panel 24 is provided with a liquid crystal display device 51 that displays various kinds of information relating to the state of the traveling machine body 2 and the cultivating work. It has a part 51e. The auto-down state display portion 51a displays a temperature/fuel display including an engine temperature display and a fuel remaining amount display, or information regarding auto-down control described later, and the notification display portion 51e displays an engine speed display. In addition, an engine speed/usage time display consisting of the total usage time display or a notification text regarding the automatic down control is displayed.

<Block diagram>
FIG. 7 shows a control block diagram in the present embodiment, and a control unit 52 capable of executing auto-down control described later includes a microcomputer 52a having a CPU 52b, a ROM 52c, a RAM 52d, an interface 52e and the like. The control unit 52 includes a steering sensor 15, a lift arm sensor 21, a vehicle speed sensor 11, a quick up lever 36, a main shift lever 30, a sub shift lever 27, a position lever 31, an automatic changeover switch 49, an automatic down timing volume 33, and a raising height. Micro 32 based on signals input from the volume 32, shuttle lever 35, turning double speed changeover switch 43, four-wheel drive changeover switch 42, backup changeover switch 37, turning up changeover switch 39, working machine lowering speed adjusting knob 29 and starter switch 34. A signal is output by the calculation of the computer 52a, the lift arm valve 20 and the alarm buzzer 53 are operated, and the lift-up lamp 22, the automatic switching lamp 50, the turning double speed lamp 46, the four-wheel drive switching lamp 45, the turning-up lamp 41, and the backup are provided. Lighting and extinguishing of the lamp 40, the automatic brake turning lamp 47, and the automatic entrance lamp 48 are controlled to display various information on the liquid crystal display device 51.

<Auto down control>
Next, regarding the automatic down control as the turning control executed by the control unit 52, an example of the flow charts of FIGS. 8 to 17, the content of the notification by the liquid crystal display device 51 of FIG. 18, and the traveling route of the tractor 1 in the cultivating work in the field H will be described. Description will be given along a schematic diagram of FIG. In the automatic down control, the tractor 1 that has reached the field edge J raises the rotary cultivator 3 in the cultivating work of the field H that is performed while the traveling machine body 2 reciprocates by repeating straight traveling and turning at the field edge J. This is a control for automatically starting the descent of the rotary cultivator 3 when the descent start line as the boundary of the working machine descent start region is reached after the turning is performed.

<Main routine>
FIG. 8 is a flowchart showing the main routine of the automatic down control. When the operator turns on the starter switch 34, the main routine is started, and as shown in FIG. 18(a), the liquid crystal display device 51 displays the temperature/fuel display of the auto-down state display portion 51a and the notification display portion 51e. An auto-down cancellation status display consisting of the engine speed and usage time display is displayed. During the execution of the main routine, the data acquisition process (step S1) to the automatic end process (step S9) are sequentially repeated until the starter switch 34 is turned off. First, the operator measures an appropriate headland width M when performing plowing work while traveling back and forth in the field H in the directions of the routes L1 and L2 shown in FIG. Specifically, for example, the right end or the left end of the rotary cultivator 3 is brought close to the ridge E to run along the ridge E, and a mark for identifying the width of the cultivated land by the rotary cultivator 3 is provided. ..

  Next, the operator makes various settings as a preliminary preparation for performing the plowing work. First, the automatic changeover switch 49 is operated to set the traveling machine body 2 to the working mode, and after the turning position of the raising height volume 32 is adjusted to the raising height adjustment position, the turning position of the automatic down timing volume 33 is set. By turning the switch from the off position to the on position, the control section 52 shifts from the auto down off state to the auto down on state, and the automatic ON lamp 48 starts blinking. Further, the operator operates the turn double speed changeover switch 43 and the four-wheel drive changeover switch 42 to set the traveling machine body 2 to the front wheel double-speed on four-wheel drive mode or the automatic brake mode, and shifts the main shift lever 30 and the sub shift lever 27. When the automatic downshift permission condition is satisfied by setting the total reduction ratio determined by the combination of the shift stage by the main transmission mechanism and the shift stage by the auxiliary transmission mechanism to be larger than a predetermined autodown reduction ratio, The ON lamp 48 lights up. In addition, the operator puts the traveling machine body 2 in the turning-up mode or the backup mode on state by operating the turning-up switching switch 39 and the backup switching switch 37 as necessary.

  When the main routine is started, the control unit 52 performs a data acquisition process for detecting the presence or absence of a predetermined turning start operation (step S1). Here, the turning start operation means switching from the neutral position of the shuttle lever 35 to the reverse position in the backup mode on state and the rotary cultivator 3 not positioned at the upper limit height, and the turning up mode on state. In addition, when the rotary cultivator 3 is not located at the upper limit height, the steering sensor 15 is switched from the OFF state to the ON state, and when the rotary cultivator 3 is stopped moving up and down, the quick-up lever 36 has a short time t1 or more. It is a raising operation.

  The operator aligns the traveling machine body 2 with the route L1 shown in FIG. 19 and performs the cultivating work while moving the traveling machine body 2 straight along the route L1 toward the field end J. When the traveling machine body 2 approaches the field end J, the operator continues the tilling work while visually confirming the position of the rotary shaft 3a, and when the rotary shaft 3a reaches the work boundary C marked with the headland width M. When any one of the turning start operations is performed, the auto-down start flag is set.

  Note that, in the present embodiment, the route L1, T, L2 shown in FIG. 19 will be described, but the traveling route at the time of turning at the field edge J is not limited to this, and for example, the traveling machine body 2 reaches the edge E. After that, the operator may turn the steering wheel 13 clockwise by α2 or more to turn the traveling machine body 2 while moving backward while the backup mode is on, so that the traveling machine body 2 is oriented to the path L2. Further, when the rotary shaft 3a reaches the work boundary C at the field end J, after the operator turns the steering wheel 13 counterclockwise by α2 or more to move the traveling machine body 2 forward and turn it approximately 90° to the left. , With the turning angle of the steering wheel 13 returned to the neutral position, the traveling machine body 2 is moved straight forward and backward to an appropriate position, and then the steering wheel 13 is turned counterclockwise by α2 or more and left while moving forward. You may turn 90 degrees and may match the direction of the traveling body 2 with the path|route L2.

<Control state processing>
Next, the control unit 52 performs a control state process (step S2) for determining whether or not to permit the process of calculating the current position of the traveling machine body 2 and the descent start line. FIG. 9 shows a subroutine of control state processing (step S2). When the control state process (step S2) is started, the control unit 52 first determines whether or not the control unit 52 is in the automatic down-on state (step S201).

  When the control unit 52 is in the auto down ON state (YES in step S201), the control unit 52 determines whether or not the auto down execution flag is set (step S202). Here, the auto-down execution flag is a flag that the control unit 52 stands in the auto-down execution state in which the position of the traveling vehicle body 2 in turning and the descending start line are calculated, and the auto-down execution state is set. For the sake of convenience, the state in which the auto-down execution flag is off is called the auto-down cancel state. When the auto-down execution flag is off (NO in step S202), the controller 52 determines whether or not the auto-down start flag is on (step S203).

  In step S203, when the auto-down start flag is off (NO in step S203), the control unit 52 returns the process to the main routine, and when the auto-down start flag is on (YES in step S203), the control is performed. The unit 52 clears the auto-down start flag (step S204) and determines whether or not the auto-down permission condition is satisfied (step S205).

  When the auto-down permission condition is not satisfied (NO in step S205), the control unit 52 returns the process to the main routine, and when the auto-down permission condition is satisfied (YES in step S205), the control unit 52 , An auto-down execution flag is set to be in the auto-down execution state, and a front-rear direction display section 51b, a left-right direction display section 51c, and a warning display section 51d are formed on the auto-down state display section 51a. 18(b), the symbols shown in FIG. 18(h) are displayed on the front/rear direction display section 51b and the left/right direction display section 51c, and the notification buzzer 53 notifies by a short sound repeated at intervals of a predetermined time t5. Is started (step S206), and the process is returned to the main routine. Here, the time when the state in which the auto-down execution flag is set is changed to the state in which the auto-down execution flag is set is referred to as the start of turning. 18(h) to 18(p) based on the results of the machine body information acquisition process (step S3) to be described later to the position flag process (step S10) on the front/rear direction display unit 51b and the left/right direction display unit 51c. One of the symbols shown in is displayed.

  In step S202, when the auto-down execution flag is set (YES in step S202), the control unit 52 determines whether or not the auto-down permission condition is satisfied (step S207), and the auto-down permission condition is determined. When not established (NO in step S207), that is, the traveling machine body 2 was once performing the turning or cultivating work in the automatic down execution state, but for some reason, the automatic down permission condition is not satisfied is performed. At this time, the control unit 52 blinks the automatic ON lamp 48 to notify the operator that the auto-down permission condition is not satisfied (step S208), and the auto-down execution flag and the auto-down start flag are set as the auto-down reset process. Are both dropped (step S210), and the automatic down release state is entered. This may be the case, for example, when the operator operates the automatic changeover switch 49 to switch the traveling machine body 2 from the working mode to the traveling mode due to the end of the plowing work.

  In step S207, when the automatic down permission condition is satisfied (YES in step S207), the control unit 52 determines whether or not the automatic down cancellation flag is set (step S209). The auto-down cancellation flag is a flag that is set when an auto-down cancellation condition, which will be described later, is satisfied in the automatic termination process (step S9) or the like in the auto-down execution state. When the auto-down cancel flag is off (NO in step S209), the control unit 52 returns the process to the main routine. When the automatic down-off state is set in step S201 (NO in step S201) or the automatic down cancellation flag is set in step S209 (YES in step S209), the control unit 52 causes the automatic down mode. Both the execution flag and the auto-down start flag are turned off, and the auto-down execution state is released as the auto-down reset processing to enter the auto-down released state (step S210), and the processing is returned to the main routine.

<Aircraft information acquisition process>
FIG. 10 is a machine body information acquisition process (step S3) of reading information such as the type and setting of a tractor, and calculating a descending reference line F, which is a reference for determining a descending start line, based on the position of the traveling machine body 2 at the start of turning. ) Shows a subroutine. When the machine body information acquisition process is started, the control unit 52 reads the maximum output of the engine stored in advance in the control unit 52 as the acquisition of the horsepower setting (step S301) and the front wheels 5 and the rear wheels as the acquisition of the tire settings. The type and size of the traveling device including 6 are read (step S302). There are a pair of front wheels 5 and a pair of rear wheels 6 and a pair of front wheels 5 and a pair of crawlers as the types of the traveling device, and the dimensions of the traveling device include the length of the crawler or the front wheel 5 and the rear wheel 6. The distance between the shafts, the distance between the left and right front wheels 5 and the rear wheels 6, and the like. Therefore, the traveling device is not limited to this embodiment, and may be a combination of the front wheels 5 and the crawlers. Next, the control unit 52 reads whether the traveling vehicle body 2 is in the front wheel double-speed off four-wheel drive mode, the front wheel double-speed on four-wheel drive mode, or the automatic brake mode (step S303).

  The turning inner circumference and turning outer circumference corresponding to various combinations of the results of step S301, step S302, and step S303 are stored in advance in the control unit 52, and the control unit 52 controls the turning inner circumference and the turning outer circumference corresponding to the combination of the above results. The circumference and the turning outer circumference are read (step S304). Here, the turning inner circumference and the turning outer circumference mean that the rear wheel 6 on the inside and the outside of the turning when the traveling machine body 2 turns 360° in a state where the steering wheel 13 is turned to the left or right maximum turning angle. Is the distance traveled by.

  Next, the control unit 52 calculates the turning circumference that is the average value of the turning inner circumference and the turning outer circumference based on the turning inner circumference and the turning outer circumference read in step S304 (step S305), and based on this turning circumference. Then, a turning radius r as a radius of curvature when the traveling vehicle body 2 turns is calculated (step S306). The turning radius r is the radius of the arc locus drawn by the machine body reference point 2a when the traveling machine body 2 turns while the steering wheel 13 is rotated to either the left or right maximum rotation angle, and the turning radius r It is calculated by dividing by 2 times the pi.

  Next, the control unit 52 reads the hitch length A, which is a distance in plan view between the rotary shaft of the rear wheel 6 and the rotary shaft 3a at the time of landing of the rotary 3b, which is stored in advance in the control unit 52 (step S307). ), the vehicle speed measured by the vehicle speed sensor 11 is read (step S308), the dashing height, the turning position of the raising height volume 32, and the turning position of the working machine lowering speed adjustment knob 29 are read, and based on the vehicle speed. The descending traveling distance D by which the machine body reference point 2a moves from the start of the descent of the rotary tiller 3 to the landing is calculated (step S309). Here, the dashing height means the descent speed after the rotary cultivator 3 is lowered to a predetermined height so that the traveling machine body 2 does not suddenly accelerate due to the rotational force of the rotary 3b when the rotary 3b rotates and is grounded. It is the height that becomes a change point of the preset descending speed when the ground is reduced and slowly grounded.

  As shown in FIG. 19, the control unit 52 sets the position of the aircraft body reference point 2a at the start of turning, that is, the turning start position as the origin O in plan view, and sets the horizontal axis X that is the rotation axis of the rear wheel 6 at this time. And a two-dimensional orthogonal coordinate system that is orthogonal to the horizontal axis X, passes through the origin O, and has the vertical axis Y with the rear side of the traveling machine body 2 at the start of turning as the positive direction, and sets the machine body information (step S3). Based on the results of steps S307 to S309 performed in step S307), the descending reference line F that is defined only by the Y coordinate and serves as a reference for calculating the descending start line is set on the coordinate system (step S310). In addition, the position of the traveling machine body 2 on the coordinate system is specified by the X coordinate of the machine body reference point 2a in the X axis of the horizontal axis and the Y coordinate of the Y axis in the vertical axis.

  A position where the position of the rotary shaft 3a of the rotary cultivator 3 landed after the turning coincides with the work boundary C which is the position of the rotary shaft 3a of the rotary cultivator 3 at the start of the turning, that is, the traveling at the start of the turning. The rotary tiller 3 lands at the work restart position G where the Y coordinate of the machine body reference point 2a is equal to twice the hitch length A in a state where the direction of the machine body 2 and the direction of the traveling machine body 2 after turning are opposite. Then, when the tilling work is restarted, the tilling work can be performed with the headland width M from the ridge E aligned. When the traveling machine body 2 is traveling along the path L2 and the descent is started before the descending traveling distance D from the work restart position G, the traveling machine body 2 travels when the traveling machine body 2 turns at the field edge J. The tilling work can be restarted from the work restart position G without stopping. In this case, the Y coordinate of the work restart position G minus the descending traveling distance D becomes the Y coordinate of the descending reference line F. After calculating the descending reference line F, the control unit 52 returns the process to the main routine. In addition, the operator operates the automatic down timing volume 33 to set the Y coordinate of the position where the descent of the rotary cultivator 3 is started with respect to the descent reference line F from the minimum -S using S that is a predetermined length. It is possible to set the descending setting line adjusted in the range of maximum +S.

<Aircraft angle processing>
FIG. 11 shows a subroutine of the machine body angle processing (step S4) for calculating the change in the orientation of the traveling machine body 2 in the automatic down execution state and determining the completion of the turning based on the calculation result. The control unit 52 determines whether or not the auto-down execution flag is set, the vehicle speed of the traveling machine body 2 is other than 0, and the steering sensor 15 is in the on state (step S401), and all are satisfied. At this time (YES in step S401), the change in the orientation of the traveling machine body 2, that is, the angle change amount in the minute time dt is calculated based on the vehicle speed and the turning radius r (step S403), and the angle change amount is accumulated to start turning. A machine body angle, which is an angle formed by the direction of the traveling machine body 2 at time and the direction of the traveling machine body 2 at the time of calculation, is calculated (step S404). When any of the above conditions is not satisfied in step S401 (NO in step S401), the angle change amount is set to 0 (step S402), and the machine body angle is calculated (step S404).

  When any turning start operation is performed by the operator, the power transmission from the PTO shaft to the rotary cultivator 3 is cut off, the rotary cultivator 3 rises to the upper limit height, and the automatic down-on state and the automatic down start condition are set. If all the automatic down permission conditions are satisfied, the automatic down execution state is entered, and the calculation of the position and orientation of the traveling machine body 2 in the field H is started. At this time, the notification buzzer 53 starts notification by a short sound repeated at intervals of a predetermined time t5, and the warning display portion 51d displays an auto-down caution display “AUTODOWN/fall caution” shown in FIG. The symbol of FIG. 18(h) is displayed on the front-rear direction display portion 51b and the left-right direction display portion 51c. The operator turns the steering wheel 13 clockwise to the maximum turning angle and runs the traveling machine body 2 along an arcuate route T having a radius of the turning radius r.

  Next, the control unit 52 determines whether the machine body angle is 90° or more (step S405), and when the machine body angle is less than 90° (NO in step S405), the control unit 52 does not reach the turn. If it is determined that the state is less than 20° and the aircraft angle is less than 20°, the symbols shown in FIG. 18(h) are displayed on the front/rear direction display unit 51b and the left/right direction display unit 51c. The symbol shown in FIG. 18(i) is displayed on 51b and the left/right direction display portion 51c (step S406), and the process is returned to the main routine. The left-right direction display unit 51c has a rectangular display unit 51i capable of switching between a non-display state in which only the outline is displayed and a display state in which the inside of the outline is displayed in the same color as the outline. When three units are arranged in the left-right direction on both the left and right sides of the section 51b and the display section 51i in the display state is displayed only on the right side, the operator rotates the steering wheel 13 in the clockwise direction and the traveling machine body is rotated. This means that running 2 will allow you to approach the descent start line. When the symbol displayed on the front-rear direction display section 51b is oriented as shown in FIG. 18(h), it means that there is a descent start line behind the traveling machine body 2, and the front-rear direction display section is shown. When the symbol displayed on 51b is oriented as shown in FIG. 18(j), it means that there is a descent start line in front of the traveling machine body 2. The operator continues to turn the traveling machine body 2 along the route T while maintaining the state where the steering wheel 13 is rotated clockwise to the maximum rotation angle while looking at the front-rear direction display portion 51b and the left-right direction display portion 51c. To do.

  In step S405, when the machine body angle is 90° or more (YES in step S405), the control unit 52 determines that the turning state has been reached (step S407), and determines whether the turning angle condition is achieved. (Step S408). The achievement of the turning angle condition means that the body angle is within a predetermined turning completion angle range in which it is determined that the turning is completed. The turning completion angle range is 180° after the aircraft body angle changes from outside the range of 180°±α3 to within 180°±α3 by using the predetermined angles α3 and α4 where α3<α4. After the vehicle body angle changes from within the range of 180°±α4 to outside the range of 180°±α4, the turning completion angle range becomes 180°±α3. In this way, by changing the turning completion angle range depending on whether the aircraft angle is within the turning completion angle range, the processing is frequently switched when the aircraft angle is near the upper limit or the lower limit of the turning completion angle range. Is preventing.

  When the turning angle condition is not achieved in step S408 (NO in step S408), the control unit 52 displays the front-rear direction display unit 51b and the left-right direction display unit 51c when the turning angle is smaller than the turning completion angle range. When the symbol shown in FIG. 18(j) is displayed and the turning angle is larger than the turning completion angle range and 270° or less, the symbol shown in FIG. 18(m) on the front-rear direction display section 51b and the left-right direction display section 51c. Is displayed and the turning angle is more than 270° and less than 300°, the symbol shown in FIG. 18(n) is displayed on the front-rear direction display section 51b and the left-right direction display section 51c, and the turning angle condition flag is cleared ( In step S409), the process is returned to the main routine.

  In step S408, when the turning angle condition is achieved (YES in step S408), the control unit 52 determines that the coordinates of the aircraft body reference point 2a at the time of calculation on the coordinate system, that is, the Y coordinate of the current position is the descent start line. If the distance is within a predetermined distance in the negative direction from the front-rear direction display portion 51b and the display portions 51i adjacent to the left and right of the front-rear direction display portion 51b are both in the display state, the symbol shown in FIG. By changing the interval of short sounds by the notification buzzer 53 to a predetermined time t6 shorter than t5, the operator is informed in advance that the descent start line is approaching. In other cases, the front-back direction display portion 51b and the left-right direction display are displayed. The symbol shown in FIG. 18(k) is displayed on the section 51c, the turning angle condition flag is set (step S410), and the process is returned to the main routine.

  The operator confirms that the symbol shown in FIG. 18(k) is displayed on the left/right direction display section 51c, returns the steering wheel 13 to the neutral position, and the symbol shown in FIG. 18(p) is displayed on the left/right direction display section 51c. Until it is displayed, the traveling machine body 2 travels straight along the route L2 in parallel with the route L1.

<Angle calculation>
FIG. 12 shows a subroutine of angle calculation (step S5) for calculating the current position based on the machine body angle. First, the control unit 52 reads the angle change amount, the machine body angle, and the vehicle speed (step S501), and based on the angle change amount, the machine body angle, and the vehicle speed, a change in the position of the traveling machine body 2 on the coordinate system in the minute time dt, that is, A coordinate change amount is calculated (step S502). Next, the control unit 52 determines whether the vehicle speed of the traveling machine body 2 is other than 0 (step S503), and when the vehicle speed is 0 (YES in step S503), maintains the current position (step S503). S504) The process is returned to the main routine, and when the vehicle speed is other than 0 (NO in step S503), the coordinate change amount is accumulated in the current position to calculate a new current position (step S505), and the process is executed in the main routine. Return to.

<Position calculation>
FIG. 13 shows a subroutine of position calculation (step S6) for calculating the descending start line based on the descending reference line F, the current position, and the descending setting line. First, the control unit 52 determines whether or not it is in the automatic down execution state (step S601), and when it is not in the automatic down execution state (NO in step S601), adopts the descending setting line as the descending start line (step S602). ), and returns the processing to the main routine. Here, the descent start line is a variable defined only by the Y coordinate, and the descent reference line F, the descent setting line, the current descent line are calculated by the position calculation (step S6) and the position determination process (step S7) described later in detail. It is a straight line that changes depending on the result of the calculation based on the position, the body angle, and the route of the traveling body 2, and when the current position reaches, the descent of the rotary cultivator 3 is started. In the automatic down execution state (YES in step S601), the control unit 52 determines that the Y coordinate of the descending setting line is greater than or equal to the Y coordinate of the descending reference line F (YES in step S603) and the descending setting line. When the Y coordinate is greater than or equal to the Y coordinate of the current position and less than the Y coordinate of the descending reference line F (YES in step S605), the Y coordinate of the descending setting line is adopted as the Y coordinate of the descending start line (step S606), and the processing is performed. To the main routine.

  In the case of the automatic down execution state, when the Y coordinate of the descending reference line F exceeds the Y coordinate of the descending setting line and is equal to or less than the Y coordinate of the current position (YES in step S607), the controller 52 starts descending. The Y coordinate of the descending reference line F is adopted as the Y coordinate of the line (step S608), and the process is returned to the main routine. When the Y coordinate of the current position exceeds the Y coordinate of the descending setting line and is less than the Y coordinate of the descending reference line F (NO in step S607), the steering sensor is in the auto down execution state. It is determined whether 15 is in the ON state or the shuttle lever 35 is in the reverse position (step S609). When the steering sensor 15 is in the on state or the shuttle lever 35 is located in the reverse position (YES in step S609), the control unit 52 sets a predetermined hysteresis value in the Y coordinate of the current position as the Y coordinate of the descending start line. The value obtained by adding γ is adopted (step S610), and the process is returned to the main routine. In step S609, when neither the steering sensor 15 is on nor the shuttle lever 35 is in the reverse position (NO in step S609), the process is returned to the main routine. In this way, in the auto-down execution state, the state in which the descending start line is set while the Y coordinate of the descending start line changes in accordance with the change of the current position and the Y coordinate of the descending setting line is maintained.

  The operator causes the traveling machine body 2 to travel forward along the route L2 while traveling straight, the Y coordinate of the current position reaches within a predetermined distance β from the descent start line, and the front-rear direction display section 51b and the left-right direction display section 51c are displayed in FIG. The pattern shown in (p) is displayed, and it is confirmed that the interval of short sounds of the notification buzzer 53 has become small, and it is known that the descent of the rotary cultivator 3 is about to start.

<Position flag processing>
Even when the current position reaches the descent start line, the traveling body 2 is greatly deviated from the route L2, the steering sensor 15 is in the ON state, and the traveling body 2 is moving backward. It is not determined that the descent start line has been properly reached, and the descent of the rotary cultivator 3 is not started. FIG. 14 shows a subroutine of a position flag process (step S10) for determining whether or not a position condition for judging that the traveling machine body 2 has properly reached the descent start line. When the Y coordinate of the current position exceeds the value obtained by adding the hysteresis value γ to the Y coordinate of the descending start line (YES in step S11), the control unit 52 drops the position condition flag and sets the position passing condition flag ( In step S14), the process is returned to the main routine. Here, the position condition flag is one of the conditions for the control unit 52 to set the lowering flag for starting the lowering of the rotary cultivator 3 in the position determination process described in detail later, and the current position is the lowering start line. It is a flag indicating that the number has been reached. The position passing condition flag is a flag indicating that the current position has reached the descending start line, but the condition for descending the rotary cultivator 3 has not been established and the condition has passed the descending start line.

  In step S11, when the Y coordinate of the current position is less than or equal to the value obtained by adding the hysteresis value γ to the Y coordinate of the descent start line (NO in step S11), the control unit 52 determines that the Y coordinate of the current position is the descent start line. It is determined whether or not it is less than the value obtained by subtracting the hysteresis value γ from the Y coordinate of (step S12). In step S12, when the Y coordinate of the current position is less than the value obtained by subtracting the hysteresis value γ from the Y coordinate of the descending start line (YES in step S12), the control unit 52 sets the position condition flag and the position passing condition flag. Both are dropped (step S13), and the process is returned to the main routine. In step S12, when the Y coordinate of the current position is greater than or equal to the value obtained by subtracting the hysteresis value γ from the Y coordinate of the descending start line (NO in step S12), the control unit 52 determines whether the position passing condition flag is set. It is determined (step S15).

  In step S15, when the position passing condition flag is set (YES in step S15) and the Y coordinate of the current position is less than the Y coordinate of the descending start line (YES in step S16), the position passing condition flag is turned off. If (YES in step S15) and the Y coordinate of the current position exceeds the Y coordinate of the descending start line (YES in step S17), the control unit 52 sets a position condition flag (step S18). When the Y coordinate of the current position is greater than or equal to the Y coordinate of the descending start line in step S16 (NO in step S16) and when the Y coordinate of the current position is less than or equal to the Y coordinate of the descending start line (step S16) ( The controller 52 returns the process to the main routine in step S17).

<Position determination processing>
FIG. 15 shows a subroutine of a position determination process (step S7) that issues a lowering request for the rotary cultivator 3 based on the result of the position flag process (step S10). First, the control unit 52 determines whether the vehicle speed is other than 0 (step S701), returns the process to the main routine when the vehicle speed is 0 (NO in step S701), and when the vehicle speed is not 0 (step S701). YES), it is determined whether the steering sensor 15 is off and the shuttle lever 35 is located at the forward position (step S702). In step S702, when the steering sensor 15 is in the on state or the shuttle lever 35 is not in the forward position (NO in step S702), the control unit 52 returns the process to the main routine. In step S702, when the steering sensor 15 is off and the shuttle lever 35 is located at the forward position (YES in step S702), the control unit 52 determines whether the position condition flag and the turning angle condition flag are set. Is determined (step S703).

  In step S703, when at least one of the position condition flag and the turning angle condition flag is set (NO in step S703), the control unit 52 returns the process to the main routine, and the position condition flag and the turning angle condition flag are set. When standing together (YES in step S703), the control unit 52 determines whether or not the descending delay operation has timed out (step S704). Here, the descending delay operation is a long-increasing operation in which the operator holds the quick-up lever 36 up for a predetermined time t2 longer than t1 in the automatic down execution state, and the descending delay operation is performed. In the state, as shown in FIG. 18(d), the temporary stop symbol 51g is displayed on the warning display portion 51d, the temporary stop state for restricting the lowering of the rotary cultivator 3 is started, and the lowering of the rotary cultivator 3 is started. Even if other conditions are satisfied, the rotary cultivator 3 is maintained at the position of the upper limit height. In the descending delay operation, if the operator holds the quick-up lever 36 by raising it for a predetermined time t3 longer than t2, the descending delay operation is timed out. In step S704, when the descending delay operation has timed out (YES in step S704), the control unit 52 sets an auto-down cancellation flag as a time-out process, and as shown in FIG. 18C, the warning display unit 51d. The stop symbol 51f is displayed until the predetermined time t4 has elapsed (step S707), and the process is returned to the main routine. In step S704, when the descending delay operation is not timed out (NO in step S704), the control unit 52 sets a work implement descending flag for starting descending of the rotary cultivator 3 and issues a descending request (step 706). , Return the process to the main routine. Further, after the descent delay operation, when the operator releases the operating hand from the quick-up lever 36 within a predetermined time t3, the descent delay operation is canceled, and the descent of the rotary cultivator 3 can be started again, and the warning display portion 51d. Is displayed as shown in FIG.

<Descent start processing>
FIG. 16 shows a subroutine of the descent start processing (step S8) in which the descent of the rotary cultivator 3 is started by operating the lift arm valve 20 based on the descent request. First, the control unit 52 determines whether or not the work implement lowering flag is set (step S801), and when the work implement lowering flag is set (NO in step S801), returns the process to the main routine and returns to the work implement. When the descending flag is set (YES in step S801), it is determined whether or not the descending delay operation is performed by the operator (step S802). In step S802, when the descending delay operation is performed by the operator (NO in step S802), the control unit 52 returns the process to the main routine, and when the descending delay operation is not performed (YES in step S802), the control unit. 52, the working machine lowering flag is cleared (step S803), the lowering of the rotary cultivator 3 is started (step S804), and the descending symbol 51h is displayed on the warning display portion 51d as shown in FIG. 18(e). The notification buzzer 53 emits a sound to notify the operator that the rotary cultivator 3 is descending (step S805), and the process is returned to the main routine.

  The operator continues the forward traveling of the traveling body 2 with the descent of the rotary cultivator 3 started, the power transmission from the PTO shaft to the rotary cultivator 3 is restarted, the rotary 3b rotates, and the rotary 3b lands. Then the plowing work is resumed.

<Automatic end processing>
FIG. 17 shows a subroutine of an automatic end processing for canceling the automatic down execution state based on the traveling route of the traveling machine body 2 in the automatic down execution state. As a condition for canceling the auto-down execution state, the control unit 52 is provided with an auto-down termination condition for being in the auto-down off state and an auto-down releasing condition for being in the auto-down cancellation state.

  First, the control unit 52 performs processing for the auto-down end position condition, which is the first auto-down end condition. In the auto-down execution state, the control unit 52 defines X coordinate <−ε1, or ε1<X coordinate, and Y coordinate <−ε1 or ε1<Y coordinate, based on a predetermined end distance ε1. It is determined whether or not there is a current position in the end position range that is outside the square (step S901). In step S901, when the current position is within the end position range (YES in step S901), the control unit 52 causes the notification display unit 51e to display the automatic down control position release display “automatic in position restriction” shown in FIG. Is turned off" for a predetermined time t4, and an automatic end process for setting the control unit 52 in the automatic down-off state is executed (step S902), and the process is returned to the main routine. After the elapse of the predetermined time t4, the control unit 52 displays the engine speed/usage time display shown in FIG. 18(a) on the notification display unit 51e and the temperature shown in FIG. 18(a) on the auto-down state display unit 51a.・Display the fuel display. In this way, when the automatic down-off state is brought about by the automatic down termination condition, the automatic down timing volume 33 is once turned to the off position and then the control unit 52 is set to the working mode in order to turn the automatic down on state again. It is necessary to change the turning position of the automatic down timing volume 33 from the off position to the on position again in a state where both the existence and the turning position of the raising height volume 32 are located at the raising height adjusting position. Don't

  In step S901, when the current position is not within the end position range (NO in step S901), the control unit 52 determines −ε1≦X coordinate< based on the end distance ε1 and the predetermined notification distance ε2 smaller than the end distance ε1. It is determined whether or not the current position is within the notification position range defined by -ε2 or ε2 <X coordinate ≤ ε1 and -ε1 ≤ Y coordinate <-ε2 or ε2 <Y coordinate ≤ ε1. Yes (step S903). In step S903, when the current position is within the notification position range (YES in step S903), the position notification process is performed by the automatic display control position notification display "position limit exceeded" shown in FIG. Is displayed, and the operator is notified of the cancellation of the auto-down execution state (step S904).

  In step S903, when the current position is not in the notification position range (NO in step S903), the control unit 52 determines −ε3<X<ε3 based on the notification distance ε2 and the predetermined reset distance ε3 smaller than the notification distance ε2. , And whether or not the current position is within the end position reset range inside the square defined by −ε3<Y<ε3 (step S905). In step S905, when the current position is within the end position reset range (YES in step S905), the control unit 52 performs the end position reset process on the notification display unit 51e as shown in FIG. A usage time display is displayed (step S906).

  Next, the control unit 52 performs processing for the auto-down end angle condition that is the second auto-down end condition. The control unit 52 determines whether or not the machine body angle in the auto-down execution state exceeds a predetermined end angle λ1 (step S907), and when the machine body angle exceeds the end angle λ1 (YES in step S907). The control unit 52 displays the auto-down angle cancellation display “automatically turns off at angle limit” on the notification display unit 51e for a predetermined time t4, and executes an automatic end process to put the control unit 52 into the auto-down off state. (Step S902), the process is returned to the main routine. After a predetermined time has elapsed, the control unit 52 displays the engine speed/usage time display on the notification display unit 51e and the temperature/fuel display on the auto-down state display unit 51a as shown in FIG. 18(a).

  In step S907, when the machine body angle does not exceed the end angle λ1 (NO in step S907), the control unit 52 determines that the machine body angle is the end angle λ1 and the predetermined notification angle λ2 smaller than the end angle λ1. It is determined whether or not it is within the notification angle range defined by λ2<machine angle≦λ1 (step S908). In step S908, when the aircraft angle is within the notification angle range (YES in step S908), an automatic down angle notification display "exceeds the angle limit" is displayed on the notification display section 51e as an angle notification process, and the operator is automatically notified. An advance notice of cancellation of the down execution state is given (step S909).

  In step S908, when the machine body angle is not within the notification angle range (NO in step S908), the control unit 52 determines whether the machine body angle is less than a predetermined reset angle λ3 smaller than the notification angle λ2 ( Step S910). In step S910, when the machine body angle is less than the reset angle λ3 (YES in step S910), the control unit 52 causes the notification display unit 51e to display the engine speed/number as shown in FIG. A usage time display is displayed (step S911).

  Next, the control unit 52 performs the process regarding the automatic end integration distance condition which is the third auto down end condition. The control unit 52 determines whether or not the integrated traveling distance from when the automatic down execution state is entered until when the automatic down execution state is removed exceeds a predetermined end integrated distance ξ1 (step S912). Here, the integrated travel distance refers to all of the travel distance of the machine body reference point 2a from the time the automatic down is executed to the time the automatic down is no longer executed, regardless of whether the vehicle is moving forward, backward, or temporarily stopped. It is the added distance. In step S912, when the total traveled distance exceeds the end totalized distance ξ1 (YES in step S912), the control unit 52 causes the notification display unit 51e to display the auto-down totalized distance cancellation display “automatic with travel restriction”. Is displayed for a predetermined time t4, an automatic end process for setting the control unit 52 in the automatic down-off state is executed (step S902), and the process is returned to the main routine. After the elapse of the predetermined time t4, the control unit 52 displays the engine speed/usage time display on the notification display unit 51e and the temperature/fuel display on the auto-down state display unit 51a as shown in FIG. 18(a).

  In step S912, when the accumulated traveling distance does not exceed the end accumulated distance ξ1 (NO in step S912), the control unit 52 determines that the accumulated traveling distance is smaller than the predetermined accumulated accumulated distance ξ1. , Ξ2<accumulated running distance≦ξ1, it is determined whether or not it is within the notification accumulated distance range (step S913). In step S913, when the integrated travel distance is within the notification integrated distance range (YES in step S913), the control unit 52 performs the integrated distance notification process on the notification display unit 51e with the auto-down integrated distance notification display “travel limit exceeded. Is displayed, and the operator is notified of the cancellation of the auto-down execution state (step S914).

  Next, the control unit 52 determines whether or not the cancellation forward/reverse traveling condition that is the automatic down cancellation condition is satisfied (step S915). Here, establishment of the cancellation forward/reverse traveling condition means that the steering sensor 15 is never turned on during the period from when the control unit 52 is in the automatic down execution state until it is not in the automatic down execution state. When the straight backward movement distance, which is the backward movement distance 2 continuously performed only in forward and backward movements, exceeds the predetermined release forward and backward movement distance ρ1 smaller than the reset distance ε3, or the control unit 52 is in the auto-down execution state. When the steering sensor 15 has not been turned on since then, the straight forward movement distance, which is the forward movement distance continuously performed only in forward and backward movements, exceeds the release forward/backward travel distance ρ1. .. In step S915, when the reverse forward/reverse traveling condition is satisfied (YES in step S915), the control unit 52 executes the automatic release process, and the notification display unit 51e displays the automatic down integrated distance release display “Driving restriction. Control is released” for a predetermined time t4, an auto-down release flag is set (step S916), the auto-down is released, and the process returns to the main routine. After the elapse of the predetermined time t4, the control unit 52 displays the engine speed/usage time display on the notification display unit 51e and the temperature/fuel display on the auto-down state display unit 51a as shown in FIG. 18(a).

  In step S915, when the release forward/reverse traveling condition is not satisfied (NO in step S915), the control unit 52 determines that the straight forward backward moving distance or the straight forward moving distance is greater than the release forward/backward traveling distance ρ1 and the release forward/backward traveling distance ρ1. Based on the small predetermined notification forward/backward travel distance ρ2, it is determined whether or not it is within the notification forward/backward travel range defined by ρ2<straight backward movement distance or straight forward movement distance≦ρ1 (step S917). In step S917, when either one of the straight-ahead backward movement distance and the straight-ahead forward movement distance is within the notification forward/backward movement range (YES in step S917), the control unit 52 causes the notification display unit 51e to automatically perform the forward/backward notification processing. The accumulated down distance notification display "travel limit exceeded" is displayed, and the operator is notified of the cancellation of the automatic down execution state (step S918), and the process is returned to the main routine.

  In step S917, when both the straight ahead moving distance and the straight ahead moving distance are not within the notification forward/backward moving range (NO in step S917), the control unit 52 determines that the straight ahead moving distance or the straight forward moving distance is the notified forward/backward moving distance. It is determined whether or not a predetermined reset forward/backward travel distance ρ3 that is smaller than ρ2 and the notification forward/backward travel distance ρ2 (step S919). In step 919, when both the straight-ahead backward moving distance and the straight-ahead forward moving distance are less than the reset forward/backward moving distance ρ3 (YES in step S919), a notification display as shown in FIG. The engine speed/usage time display is displayed on the section 51e (step S920), and the process is returned to the main routine.

  Further, in step S1, the control unit 52 performs processing for a quick up cancellation condition that is an auto down cancellation condition. When the operation of lowering the quick-up lever 36 for a predetermined time t7 or more is performed in the automatic down execution state, the control unit 52 starts the descent of the rotary cultivator 3, sets the automatic down cancellation flag, and enters the automatic down cancellation state. .. Further, when the quick-up lever 36 is lifted for less than the predetermined time t2 in the automatic down execution state, the control unit 52 causes the warning display portion 51d to display the stop symbol 51f shown in FIG. 18C for the predetermined time t4. The automatic down cancellation flag is set and the automatic down cancellation state is entered.

<Effects of this embodiment>
From the above, the control unit 52 sets the descending start line on the coordinate system with the turning start position of the traveling machine body 2 as the origin O, and descends the rotary cultivator 3 when the current position of the traveling machine body 2 reaches the descending start line. Therefore, when the tractor 1 travels back and forth to cultivate the field H, the operator can select an arbitrary route to turn the traveling machine body 2 and the timing of starting the descent of the rotary cultivator 3. The headland width M from the ridge E can be easily made uniform without the necessity of making a judgment by themselves. Further, it is possible to prevent an operator from performing an erroneous operation such as erroneous timing of starting the descent of the rotary cultivator 3, formation of an uncultivated part of the field H, double cultivating work, etc., and efficient cultivating work can be performed.

  Further, the control unit 52 stores in advance the turning inner circumference and the turning outer circumference in each of the front wheel double-speed on four-wheel drive mode, the front wheel double-speed off four-wheel drive mode, and the automatic brake mode, and the turning inner circumference corresponding to the selected mode. Since the current position is calculated based on the turning outer circumference, the error between the calculation result of the descent start line due to the difference between these modes and the position where the operator expects the descent start of the rotary cultivator 3 is reduced, and The headland width M can be aligned to a predetermined width with high accuracy.

  Further, the control unit 52 does not set the auto-down execution state when the two-wheel drive mode unsuitable for the tilling work in the field H or the high-speed stage having the predetermined reduction ratio or less is selected. Unintentional lowering of the rotary tiller 3 can be prevented. Further, since the control unit 52 sets the descent start line based on the upper limit height of the rotary cultivator 3 and the vehicle speed in the automatic down execution state, the time required from the descent of the rotary cultivator 3 to the touchdown is set. It is possible to prevent the landing position from varying due to the difference in the height of the ground and to align the headland width M from the edge with a predetermined width with high accuracy.

  Moreover, since the control part 52 sets a descent start line based on the upper limit height of the rotary cultivator 3 adjusted by the operation of the raising height volume 32, the rotary cultivator 3 is grounded after starting descent. It is possible to prevent the ground contact position from varying due to the difference in the time required until the headland width M from the edge is aligned with a predetermined width with high accuracy. Further, by operating the work implement descending speed adjusting knob 29, the descending speed of the rotary cultivator 3 can be adjusted by the automatic down control, and the control unit 52 sets the descending start line based on the descending speed of the rotary cultivator 3. Therefore, the convenience is improved, and the variation of the ground contact position due to the difference in the time required from the descent of the rotary tiller 3 to the ground contact is prevented, and the headland width M from the ridge is increased to a predetermined width. Can be aligned with accuracy. Further, since the Y coordinate of the descending start line can be adjusted by the automatic down timing volume 33, when the descending start line has an error due to the slip of the traveling device such as the front wheels 5 and the rear wheels 6, or the field which is not rectangular, For example, it is possible to easily deal with the case of performing cultivating work in a field such as a trapezoid, improving convenience and aligning the headland width M from the ridge to a predetermined width with high accuracy.

  Further, in the automatic down release state, the backup mode is turned on, and the neutral position of the shuttle lever 35 is switched from the neutral position to the reverse position when the rotary cultivator 3 is not located at the upper limit height, and the turning up mode is turned on. And at least one of the operation of switching the steering sensor 15 from the off state to the on state and the raising operation of the quick up lever 36 for a predetermined time t1 or more in a state where the rotary cultivator 3 is not located at the upper limit height. The automatic down execution state is triggered by the detection of the, and the descending start line is set on the coordinate system having the turning start position as the origin O. Therefore, it is possible to cope with various turning operation procedures which are different depending on the operator's preference and the like. It is possible to improve the degree of freedom of operations to be performed and reduce the operation burden on the operator by reducing unnecessary operation procedures.

  Further, in a state where the machine body angle does not reach the turning angle condition, the control unit 52 does not lower the rotary cultivator 3 even when the traveling machine body 2 reaches the lowering start line, so that the rotary cultivator not intended by the operator. The descent of the machine 3 can be prevented. Further, since the descending start line is defined only by the coordinates in the front-rear direction of the machine body reference point 2a at the start of turning, the operator can freely select the horizontal position of the traveling machine body 2 at the time of resuming work. For example, since the cultivating work can be performed every other row, the degree of freedom in operation can be improved and the processing load on the control unit 52 can be reduced.

  In addition, since the descent of the rotary cultivator 3 can be temporarily suspended by operating the quick-up lever 36 for a predetermined time t2 or more in the automatic down execution state, the operator can slip the front wheel 5 or the rear wheel 6 and When it is expected that the timing when the descent of the rotary cultivator 3 is started by the automatic down control is started earlier than the timing when the descent that the operator desires is started due to the operator making a mistake in the steering operation, the rotary cultivator 3 The start of the descent of can be paused temporarily. Further, the operator can know in advance the timing at which the rotary cultivator 3 will start descending by the advance notice from the notification buzzer 53 that the interval of the short sound changes from t5 to t6, and the rotary cultivator based on the advance notice. When it is judged that the timing of starting descent of 3 is too early, the rotary cultivator 3 is temporarily put into a rest state, and the descent of the rotary cultivator 3 can be started while visually confirming the restart position of the work. .. Further, in the automatic down execution state, the automatic down execution state is canceled by a short raising operation of the quick up lever 36 for less than the predetermined time t2, so that the descent of the rotary cultivator 3 can be easily interrupted and further quick up operation can be performed. Since the automatic down execution state can be set again by the raising operation of the lever 36, the operator can easily perform the turning again and the convenience can be improved.

  Further, the control unit 52 starts the notification to the operator by the short sound of the notification buzzer 53 in the automatic down execution state, the aircraft angle is within the turning complete angle range, and the Y coordinate of the aircraft reference point 2a is in front of the descent start line. Since the interval of the short sound of the notification buzzer 53 is shortened when the distance becomes less than or equal to the predetermined distance β, the operator can know that the automatic down is being executed and that the descending start line is near in advance. Therefore, the operator can predict the difference between the tilling restart position by the automatic lowering of the rotary tiller 3 with automatic down control and the tilling restart position desired by the operator. Further, when the automatic down execution state is entered, the control unit 52 starts notifying the operator by the display of the liquid crystal display device 51, displays the direction of the descending start line with the current position of the traveling machine body 2 as a reference, and the descending start line. Since the display is changed according to the distance to, the operator can know the direction in which the traveling machine body 2 should be steered and also know in advance that the descending start line is near. This reduces the operational burden on the operator, and before the rotary tiller 3 starts to descend, the difference between the tiller restart position and the operator's desired tiller restart position due to the automatic lowering of the rotary tiller 3 with automatic down control is set. Can be predicted by the operator.

  Further, the control unit 52 calculates the current position and the machine body angle of the traveling machine body 2 in the auto-down execution state, and when the traveling machine body 2 is separated from the turning start position by more than the predetermined distance ε1, the turning angle is predetermined from 180°. When the vehicle is opened at an angle or more, or when the accumulated traveling distance of the traveling machine body 2 exceeds the predetermined distance ξ1, the automatic down-off state is set. Therefore, when the plowing work performed while reciprocating the field H is completed and traveling on the headland, It is possible to prevent the descent of the rotary cultivator 3 which is not intended by the operator, such as after going out of the field.

  Further, when the straight traveling backward movement distance exceeds the predetermined forward-reverse traveling release distance ρ or the straight forward movement distance exceeds the forward-reverse traveling cancellation distance ρ, the control unit 52 executes the auto down while maintaining the auto down ON state. Since the state is released, it is possible to prevent the rotary cultivator 3 from being lowered unintentionally by the operator, and it is possible to set the automatic down execution state again with a few operations.

  Further, the position of the traveling machine body 2 in the auto-down execution state is calculated by the steering sensor 15 and the vehicle speed sensor 11 which can use inexpensive contact switches, optical sensors, etc. without using expensive gyro sensors, GPS, etc. Therefore, the cost can be suppressed. In the automatic down control, the current position and the machine body angle of the traveling machine body 2 are calculated based on the value of the turning radius r which varies depending on the maximum output of the engine and the type and size of the traveling device such as the front wheels 5 and the rear wheels 6. The control unit 52 can be shared between the traveling machines 2 having different r. Further, the turning radius r of the traveling machine body 2 is calculated based on whether or not the front wheel double speed control or the automatic brake control is executed, and the current position and the machine body angle of the traveling machine body 2 are calculated from the turning radius r. The accuracy of calculating the current position of the machine body 2 is improved, and the headland width M from the edge can be aligned with a predetermined width with high accuracy.

  Although the vehicle speed is set to detect the rotation of the one rear wheel 6 and the rotation of the rear wheel drive shaft, the rotation of the other part may be detected instead. For example, instead of the rotation of the rear wheel drive shaft. The rotation of the drive shaft may be detected, or the rotation of both the left and right rear wheels 6 may be detected. Although the main transmission mechanism and the sub transmission mechanism are multi-stage transmission mechanisms, if the total reduction ratio, which is the ratio of the engine speed to the rear wheel 6 speed, can be detected, The main speed change mechanism and the sub speed change mechanism may be a continuously variable speed change mechanism, or may be configured to include only one of them. As the turning start operation, an operation of raising the rotary cultivator 3 by operating the position lever 31 may be added.

  It should be noted that the visual notification to the operator is based on the change of the design or the notification text of the liquid crystal display device 51, but instead, an organic EL display other than liquid crystal or a dot matrix display device of an LED lamp may be used, or light emission may be performed. The notification may be made by changing the color or position of the display device. The various operation tools for inputting to the control unit 52 may be a touch panel provided on the liquid crystal display device 51 instead, or an input device provided outside the traveling machine body 2 capable of wireless communication. It may be. The operator may operate the tractor 1 from a distance without getting on the vehicle, and the steering device may be driven by a motor or hydraulic control to steer the front wheels 5. The steering wheel 13 may be a lever or a button that can swing or move horizontally, and the operation of the steering wheel 13 is not limited to detection of either the ON state or the OFF state, and the operation angle can be detected numerically. Alternatively, the control unit 52 may be configured to be able to perform calculation based on the turning radius r calculated according to the operation angle. The operation of the steering wheel 13 may directly detect the rotation of the steering wheel 13, or may be detected by the amount of movement of the tie rod or the amount of inclination of the front wheel 5. The control unit 52 may be formed by a discrete circuit or may be integrally formed as a semiconductor integrated circuit element.

  In addition, although the said embodiment demonstrated the tractor 1 provided with the rotary cultivator 3, it is not restricted to this, and a working machine may be a scraping working machine, a plow, etc., and the work which can be raised/lowered to the traveling machine body 2, such as a rice transplanter. It is similarly applicable to other work vehicles provided with a machine.

1 work vehicle (tractor)
2 Traveling machine 3 Working machine (rotary tiller)
5 Front wheels 6 Running section (rear wheels)
12 Steering unit (steering device)
16 Lifting device (lifting link mechanism)
29 Lowering speed setting means (working machine lowering speed adjustment knob)
32 Lifting height adjustment means (raising height volume)
33 Descent start area adjusting means (auto down timing volume)
r Radius of curvature (turning radius)

Claims (5)

A pair of left and right front wheels and a pair of left and right traveling units arranged behind the front wheels, a traveling machine body supported by the traveling machine body, a steering section for manipulating the traveling machine body, and a lifting device for elevating the working machine. In the work vehicle,
Setting a working machine descent start region based on the position at the start of turning of the traveling machine body, calculating the position of the traveling machine body based on the radius of curvature by the steering section and the traveling distance by the front wheels and the traveling section, When the traveling machine body reaches the working machine lowering start region, the lifting control starts and lowers the working machine, and a turning control,
A front wheel speedup control that drives the peripheral speed of the front wheels to the peripheral speed of the traveling unit when the traveling machine body turns, and an automatic braking control that brakes the traveling unit that is on the inside of the turning when the traveling machine body turns. And at least one of
In the turning control, when the front wheel speed-up control or the automatic braking control is being executed, the radius of curvature is calculated with a radius of curvature based on the executed control,
A working vehicle characterized by the above. Drive state switching means capable of selecting one of a four-wheel drive state in which power is transmitted to the front wheels and the traveling portion and a two-wheel drive state in which power is transmitted only to the traveling portion;
A speed changer capable of adjusting the reduction ratio of the front wheels and the traveling section,
The turning control sets the working machine lowering start region on condition that the four-wheel drive state is selected and the reduction ratio of the traveling unit is adjusted to be a reduction ratio larger than a predetermined reduction ratio. Will be done
The work vehicle according to claim 1. Equipped with a rising height adjusting means capable of adjusting the upper limit height when raising the working machine,
The turning control is configured to set the working machine lowering start region based on an upper limit height of the working machine and a traveling speed of the traveling machine body,
The work vehicle according to claim 1. A descending speed setting means for setting a descending speed when descending the working machine,
The turning control comprises setting the working machine lowering start region based on a lowering speed of the working machine and a traveling speed of the traveling machine body,
The work vehicle according to any one of claims 1 to 3. A descending start area adjusting means for adjusting the working machine descending start area,
The work vehicle according to any one of claims 1 to 4.

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