JP4605667B2 - Work vehicle control device - Google Patents

Description

In the present invention, when the turning angle of the front wheel detected by the turning angle detecting means is equal to or greater than a predetermined rising angle, the automatic raising means for switching the state of the vehicle body from the working state to the non-working state or the turning angle detecting means The present invention relates to a control device for a work vehicle including front wheel speed increasing means for switching the driving state of front wheels and rear wheels from a constant speed driving state to a speed increasing driving state when a front wheel turning angle is equal to or greater than a predetermined speed increasing angle .

  As a conventional technique, for example, as disclosed in Patent Document 1, the cutting angle of the front wheel is detected by a cutting angle detector (13 in FIG. 5 of Patent Document 1), and the cutting angle of the front wheel is equal to or greater than a predetermined cutting angle. Then, a tractor having an automatic lifting mechanism that lifts the ground work machine (30 in FIG. 4 of Patent Document 1) is known.

Japanese Patent Publication No. 6-34643 (see FIGS. 4 and 5)

  The tractor of Patent Document 1 is configured such that the ground work machine rises when the turning angle of the front wheel is equal to or greater than a predetermined turning angle regardless of whether the tractor is turning. Therefore, for example, when the predetermined cutting angle is set to a small angle, for example, when traveling along the ridge in a deformed field where the ridge is curved, or when the handle is taken while traveling straight due to unevenness of the field, etc. Although the cutting angle of the front wheel exceeds the predetermined cutting angle, the ground work machine rises and the tilling work is interrupted even though it is plowing, and continuous tilling work cannot be performed. There was a problem that became worse.

  Conversely, for example, if the predetermined cutting angle is set to a large angle, after the headland turning (turning about 180 degrees at the heel) is started, the cutting angle of the front wheel reaches the predetermined cutting angle and the ground work machine rises. The time until is longer. For this reason, for example, there is a problem that the ground working machine is in a state of turning while dragging, and the field working machine is damaged by the ground working machine.

  An object of the present invention is to realize a control device for a work vehicle that can switch the state of a vehicle body from a working state to a non-working state with high accuracy in accordance with the state of the field and the content of the work.

[I]
(Constitution)
The first feature of the present invention resides in that the control device for a work vehicle is configured as follows.
A working device is mounted on the vehicle body so as to be movable up and down, and includes a turning angle detecting means for detecting a turning angle of a front wheel, a vehicle speed detecting means for detecting a vehicle speed, and a steering speed detecting means for detecting a steering speed of a steering handle, When the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than a threshold value and the turning angle of the front wheel detected by the turning angle detecting means is greater than or equal to a predetermined rising angle, the state of the vehicle body is An automatic raising means for switching from a working state in which the device is lowered to a lowered position to a non-working state in which the working device is raised to a raised position, and the higher the vehicle speed detected by the vehicle speed detecting means, the higher the threshold value. It is set.

(Function)
According to the first feature of the present invention, focusing on the tendency that the steering speed of the steering wheel tends to increase when the vehicle speed increases compared to when the vehicle speed is low, the threshold value is set higher as the vehicle speed increases. Thus, when the vehicle speed is high, the threshold value is changed to a high value, and unless the steering speed of the steering wheel is relatively fast, the automatic lifting means does not operate and the vehicle body state is switched from the working state to the non-working state. It becomes difficult to change. On the other hand, when the vehicle speed is low, the threshold value is changed to be low, and the automatic raising means operates at a relatively slow steering speed of the steering handle, so that the vehicle body state is easily switched from the working state to the non-working state.

Here, in general, for example, when traveling along a reed in a deformed field where the reed is curved or when traveling straight on a farm field, it is often performed at a relatively high speed, and the steering handle is compared. In such a case, the threshold value is changed to be high so that it is difficult to switch the vehicle body state to the non-working state. Can be prevented from being switched to the non-working state, and work on the field can be performed continuously without interruption.
In other words, when the vehicle speed increases, the threshold value is increased to make it difficult to switch the vehicle body state to the non-working state. When the steering wheel is taken while traveling straight due to unevenness etc., the state of the vehicle body can be prevented from being switched to the non-working state and the working device can be prevented from rising to the raised position, and the working device has been lowered to the lowered position. The work in the state can be performed continuously without interruption.

In general, for example, when turning a headland (turning about 180 degrees at the shore), the vehicle is often driven at a relatively low speed, and the steering handle is often operated relatively quickly. In such a case, by changing the threshold value to make it easier to switch the vehicle body state to the non-working state, the vehicle body state can be quickly switched to the non-working state. It is possible to eliminate problems caused by delays in switching.
In other words, when the vehicle speed decreases, the threshold value is changed to be low so that the state of the vehicle body can be easily switched to the non-working state. For example, when headland turns (turning about 180 degrees at the shore) Thus, the working device can be quickly raised to the raised position, and it is difficult for a state of turning while dragging the working device to prevent the working device from being damaged.

(The invention's effect)
According to the first feature of the present invention, the working device can be raised with high accuracy in accordance with the state of the field and the content of the work .

[II]
(Constitution)
The second feature of the present invention resides in the following configuration in the work vehicle control device of the first feature of the present invention.
The threshold value is set so as to increase continuously as the vehicle speed detected by the vehicle speed detecting means increases.

(Function)
According to the second feature of the present invention, the “action” described in the preceding item [I] is provided in the same manner as the first feature of the present invention, and in addition to this, the following “action” is provided.
According to the second feature of the present invention, the threshold value gradually increases continuously as the vehicle speed increases, so that an appropriate threshold value can be set finely according to the vehicle speed. Thereby, the automatic raising means can be operated at an appropriate steering speed threshold value.

(The invention's effect)
According to the second feature of the present invention, the “effect of the invention” described in the preceding item [I] is provided in the same manner as the first feature of the present invention. In addition, the following “effect of the invention” is provided. ing.
According to the second feature of the present invention, the state of the vehicle body can be switched from the working state to the non-working state with higher accuracy.

[III]
(Constitution)
The third feature of the present invention resides in the following configuration of the work vehicle control device of the first feature or the second feature of the present invention.
When the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than the threshold value, and when the front wheel turning angle detected by the turning angle detecting means is greater than or equal to a predetermined acceleration angle, the front wheels and the rear wheels Front wheel speed increasing means for switching the driving state from a constant speed driving state in which the front wheels are driven at a constant speed at substantially the same peripheral speed as the rear wheels to a speed increasing driving state in which the front wheels are driven at a speed higher than the peripheral speed of the rear wheels. It is.

(Function)
According to the third feature of the present invention, the “action” described in the preceding item [I] [II] is provided in the same manner as the first feature or the second feature of the present invention. Is provided.
According to the third feature of the present invention, when the vehicle speed increases, the threshold value is changed to be high so that it is difficult to switch the driving state of the front wheels and the rear wheels to the acceleration driving state. When driving along a ridge on a paddy field, or when the steering wheel is taken while traveling straight due to unevenness in the field, etc., the driving state of the front wheels and rear wheels is switched to the acceleration driving state, and the front wheels are driven at an acceleration This can be prevented, and the operation in the constant speed driving state in which the front wheels are driven at a constant speed can be continuously performed.
In addition, when the vehicle speed decreases, the threshold value is changed to be low so that the driving state of the front and rear wheels can be easily switched to the acceleration driving state. ), The front wheels can be driven to increase speed quickly and can be turned more quickly.

(The invention's effect)
According to the third feature of the present invention, the “effect of the invention” described in the preceding paragraphs [I] and [II] is provided in the same manner as the first feature or the second feature of the present invention. “Effect of the invention” is provided.
According to the third feature of the present invention, the front wheels can be driven at high speed with high accuracy in accordance with the situation of the field and the content of the work.

[IV]
(Constitution)
A fourth feature of the present invention resides in the following configuration in the work vehicle control device of the third feature of the present invention.
If the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than the threshold value, and the turning angle of the front wheel detected by the turning angle detecting means is greater than or equal to the predetermined acceleration angle, Rear wheel braking means for operating the rear wheel side brake to the braking side is provided.

[V]
(Constitution)
The fifth feature of the present invention is to configure a control apparatus for working vehicle as follows.
A steering angle detecting means for detecting a turning angle of the front wheel, a vehicle speed detecting means for detecting the vehicle speed, and a steering speed detecting means for detecting the steering speed of the steering handle, the steering of the steering wheel detected by the steering speed detecting means. If the speed is equal to or greater than the threshold value and the angle of the front wheels detected by the angle-of-cut detection means is equal to or greater than a predetermined acceleration angle, the driving state of the front wheels and the rear wheels is set to approximately the same circumference as the rear wheels. A front wheel speed increasing means for switching from a constant speed driving state at a constant speed to a speed increasing driving state in which the front wheels are driven at a higher speed than the peripheral speed of the rear wheels, and the vehicle speed detected by the vehicle speed detecting means is increased. The threshold value is set higher .

(Function)
According to the onset Ming fifth feature, when the vehicle speed increases, by increasing change thresholds, by hardly cut instead the driving state of the front wheels and the rear wheels overdrive condition, for example rib is curved or the like When driving along a ridge on a deformed paddy field, or when the steering wheel is taken while traveling straight due to unevenness in the field, etc., the driving state of the front and rear wheels is switched to the accelerated driving state and the front wheels are accelerated. Driving can be prevented, and work in a constant speed driving state in which the front wheels are driven at a constant speed can be continuously performed.
In addition, when the vehicle speed decreases, the threshold value is changed to be low so that the driving state of the front and rear wheels can be easily switched to the acceleration driving state. ) And the like, the front wheels can be driven to increase speed quickly and turn more quickly.

(The invention's effect)
According to the fifth aspect of the present invention, the front wheels can be driven at high speed with high accuracy in accordance with the situation of the field and the content of the work.

[VI]
(Constitution)
A sixth feature of the present invention resides in the following configuration in the work vehicle control device of the fifth feature of the present invention.
If the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than the threshold value, and the turning angle of the front wheel detected by the turning angle detecting means is greater than or equal to the predetermined acceleration angle, Rear wheel braking means for operating the rear wheel side brake to the braking side is provided.
[VII]
(Constitution)
A seventh feature of the present invention resides in the following configuration in the work vehicle control device of the first to sixth features of the present invention.
The threshold value is provided with an upper limit portion in which the threshold value becomes constant in a high speed range where the vehicle speed detected by the vehicle speed detecting means is high. The threshold is configured not to change.

[Overall structure of tractor]
Based on FIGS. 1-6, the whole structure of the tractor as an example of a working vehicle is demonstrated. FIG. 1 is an overall left side view of the tractor, and FIG. 2 is a schematic view showing the structure of the steering device 12. FIG. 3 is a plan view of the vicinity of the operating unit 4, and FIG. 4 is a schematic plan view showing a transmission configuration of the tractor. FIG. 5 is a schematic diagram showing an operation structure of the transmission switching device 26 and the side brake 41, and FIG. 6 is a block diagram of the control device 50 for the tractor.

  As shown in FIG. 1, an engine 19 is disposed at the front of the vehicle body 1, and a pair of left and right steerable front wheels 2 and a pair of left and right rear wheels 3 are disposed at the front and rear of the vehicle body 1. Thus, the tractor travels and turns according to the operation of the steering handle 6 of the driver seated on the driver seat 5 of the driver 4.

  A mission case 7 is disposed at the rear of the vehicle body 1. A pair of left and right lift arms 8 are linked to the rear upper part of the transmission case 7 so as to be swingable up and down around a left and right axis, and a rotary work is performed on the rear part of the transmission case 7 via an elevating link mechanism 9. Device R is connected.

  The elevating link mechanism 9 includes an upper link 9 a and a pair of left and right lower links 9 b, and a linkage link 9 c is linked between the lower link 9 b and the lift arm 8 of the elevating link mechanism 9. .

  A hydraulic lift cylinder 10 linked to the lift arm 8 is housed in the upper part of the transmission case 7. By operating the lift cylinder 10, the lift arm 8 is swung up and down to raise and lower the link. The rotary work device R connected to the rear end portion of the lower link 9b of the mechanism 9 is configured to be driven up and down. The rotary working device R is equipped with a rear cover Ra that swings up and down as the tillage depth in the rotary working device R varies.

  A rearward PTO shaft 11 for taking out power from the engine 19 is provided at the rear part of the transmission case 7, and the rotary work device R can be rotationally driven by linking the rotary work device R to the PTO shaft 11. It is configured as follows.

  The elevating cylinder 10 is composed of a hydraulic cylinder, and is rotated by power from the engine 19 via a three-position switching electromagnetic elevating control valve 47 connected to a control device 50 described later (see FIG. 6). It is connected to a driving hydraulic pump (not shown). Thus, by operating the lift control valve 47 to the raised position, the lift cylinder 10 can be extended and the rotary working device R can be raised, and by operating the lift control valve 47 to the lowered position, the lift cylinder 10 And the rotary working device R can be lowered. In addition, the position of the rotary work apparatus R raised or lowered can be maintained by operating the elevation control valve 47 to the neutral position.

  As shown in FIG. 2, the steering device 12 includes a power cylinder 13, an operation valve 14, and a metering pump 18. A different configuration may be adopted as the steering device 12, and not the hydraulic steering device 12 using the power cylinder 13 or the like, but the steering device 12 that is not a power steering type that does not include the power cylinder 13, or other than the power cylinder 13. You may employ | adopt the steering device 12 provided with the actuator.

  The power cylinder 13 is linked to the knuckle arms 2 a of the left and right front wheels 2, and the power cylinder 13 is connected to a hydraulic pump 16 linked to the engine 19 via an operation valve 14 and a hydraulic circuit 15. Yes. A metering pump 18 is connected to the operation valve 14 via a hydraulic circuit 17, and an input shaft 18 a of the metering pump 18 is linked to a handle operation shaft 6 a of the steering handle 6.

  Thus, when the steering handle 6 is operated and the input shaft 18a of the metering pump 18 is rotated, the operation valve 14 is operated according to the operation amount of the input shaft 18a, and pressure oil is supplied from the operation valve 14 to the power cylinder 13. Is supplied, and the left and right front wheels 2 are knuckled in the steering direction according to the rotation direction of the steering handle 6 by the operation of the power cylinder 13 and at the cutting angle according to the operation amount of the input shaft 18a of the metering pump 18. The arm 2a is swung. Then, the steering operation is performed so that the vehicle body 1 travels in the traveling direction corresponding to the operation direction of the steering handle 6 according to the operation amount of the steering handle 6.

  As shown in FIG. 4, the power from the engine 19 is transmitted to the gear-type main transmission 21 provided inside the transmission case 7 via the main clutch 20. The driving power shifted by the main transmission 21 is transmitted to the front wheel transmission system 24 and the rear wheel transmission system 25 via a forward / reverse switching device 22 and a gear-type auxiliary transmission 23.

  The power transmitted to the front wheel transmission system 24 is transmitted to the left and right front wheels 2 via the transmission switching device 26 and the front wheel differential mechanism 27, and the power transmitted to the rear wheel transmission system 25 is transmitted to the rear wheels. Is transmitted to the left and right rear wheels 3 via the differential mechanism 28 for use.

  A part of the power from the main transmission 21 is transmitted to the PTO clutch 29 without shifting, and the power from the PTO clutch 29 is provided at the rear portion of the transmission case 7 via the PTO transmission 30. It is transmitted to the shaft 11. As a result, the rotary of the rotary working device R linked to the PTO shaft 11 is driven to rotate.

  As shown in FIGS. 3 and 4, the main clutch 20 is linked to a clutch pedal 31 provided in the driving unit 4, and when the clutch pedal 31 is depressed, the main clutch 20 is moved from the on-side to the off-side. Can be operated. Accordingly, by operating the main clutch 20 to the disengagement side, the transmission of power to the main transmission 21 side can be interrupted.

  The main transmission 21 is linked to a main transmission lever 32 disposed on the left side of the driver seat 5. The operation position of the main transmission lever 32 can be switched between a plurality of forward shift positions on the forward side (or a plurality of reverse shift positions on the reverse side) and a forward neutral position (or reverse neutral position) by its swinging operation. Thus, the state of the main transmission 21 is switched to a shift state corresponding to the operation position of the main transmission lever 32.

  The sub-transmission device 23 is linked to a sub-transmission lever 33 disposed behind the main transmission lever 32, and a shift state corresponding to the operation position of the sub-transmission lever 33 is obtained by swinging the sub-transmission lever 33. Switch to.

  The PTO transmission 30 is linked to a PTO transmission lever 34 disposed on the laterally outer side of the auxiliary transmission lever 33, and the PTO transmission lever 34 is operated to swing according to the operation position of the PTO transmission lever 34. Switch to state.

  The forward / reverse switching device 22 is linked to a shuttle lever (forward / reverse switching lever) 35 disposed on the left side of the steering handle 6. The shuttle lever 35 is configured so that its operation position can be switched between a forward position and a reverse position by its swinging operation, and is neutrally biased to a neutral position between the forward position and the reverse position. Thus, when the shuttle lever 35 is operated from the neutral position to the forward movement position, the forward / reverse switching device 22 is switched to the forward movement state, and when the shuttle lever 35 is operated from the neutral position to the reverse movement position, the forward / backward switching device 22 is changed to the reverse movement state. Can be switched.

  Thus, by operating the shuttle lever 35 to the forward position and operating the main speed change lever 32, the vehicle body 1 can be moved forward in a speed change state corresponding to the forward speed change position of the main speed change lever 32. The vehicle body 1 can be stopped by operating the lever 32 to the forward neutral position. By operating the shuttle lever 35 to the reverse position and operating the main speed change lever 32, the vehicle body 1 can be moved backward in a speed change state corresponding to the reverse speed change position of the main speed change lever 32. The vehicle body 1 can be stopped by operating to the reverse neutral position.

  In the tractor in this embodiment, an example in which a gear-type transmission is adopted as the main transmission 21 is shown, but the main transmission 21 is configured by a hydrostatic continuously variable transmission (HST, not shown). May be. In this case, the shuttle lever 35 and the forward / reverse switching device 22 described above are abolished, and the HST lever for switching the forward position, the neutral position, and the reverse position of the hydrostatic continuously variable transmission instead of the main transmission lever 32 described above (see FIG. (Not shown), and the forward / backward speed of the vehicle body 1 may be changed steplessly by the swinging operation of the HST lever.

  As shown in FIGS. 4 and 5, the transmission switching device 26 is connected to a gear type via first and second clutches 36 and 37 that connect and disconnect power transmission from the auxiliary transmission 23 to the left and right front wheels 2. First and second transmission mechanisms 38 and 39 are provided. The first and second clutches 36 and 37 are constituted by multi-plate hydraulic clutches, and are connected to the engine via a front wheel state switching valve 40 which is a three-position switching type electromagnetic valve connected to a control device 50 described later. It is connected to a hydraulic pump (not shown) that is rotationally driven by power from 19.

  When the front wheel state switching valve 40 is operated to transmit power to the left and right front wheels 2 via the first clutch 36 and the first transmission mechanism 38, the state of the transmission switching device 26 is switched to the front wheel driving state, The front wheel 2 is rotationally driven so that the peripheral speed of the front wheel 2 is substantially the same as the peripheral speed of the left and right rear wheels 3.

  When the front wheel state switching valve 40 is operated to transmit power to the left and right front wheels 2 via the second clutch 37 and the second transmission mechanism 39, the state of the transmission switching device 26 is switched to the front wheel acceleration state, The front wheel 2 is driven to increase in speed so that the peripheral speed of the front wheel 2 is approximately twice the peripheral speed of the left and right rear wheels 3.

  When the front wheel state switching valve 40 is operated to switch the transmission switching device 26 to the neutral position, the state of the transmission switching device 26 is switched to the front wheel driven state, and transmission of power to the left and right front wheels 2 is interrupted.

  The left and right sides of the mission case 7 are equipped with multi-plate left and right side brakes 41. The left and right side brakes 41 are separately linked to a pair of left and right brake pedals 42 disposed at the foot of the driving unit 4 via a brake cylinder 43 and a linkage rod 44. As a result, when the left and right brake pedals 42 are depressed, the corresponding rear wheel 3 is braked with a braking force corresponding to the amount of depression of the brake pedal 42.

  The left and right brake cylinders 43 are constituted by single-acting hydraulic cylinders, and are supplied from the engine 19 via a brake braking switching valve 45 that is a three-position switching electromagnetic type connected to a control device 50 described later. It is connected to a hydraulic pump (not shown) that is rotated by power. By operating the brake braking switching valve 45, the left and right brake cylinders 43 can be shortened separately, and the left and right side brakes 41 can be operated separately on the braking side. Accordingly, even when the brake pedal 42 is not depressed, the right or left side brake 41 is moved to the braking side by shortening the right or left brake cylinder 43 by operating the brake braking switching valve 45. Can be operated.

  The PTO clutch 29 is composed of a multi-plate hydraulic clutch, and is connected to a PTO state switching valve 46 which is a two-position switching electromagnetic type connected to a control device 50 described later (see FIG. 6). Thus, by operating the PTO state switching valve 46, the state of the PTO clutch 29 is changed from the main transmission 21 to the PTO transmission 30 to the on state where power is transmitted from the main transmission 21 to the PTO transmission 30. It can be switched to a cut-off state that interrupts power transmission.

  As shown in FIG. 6, detection devices such as a steering angle sensor 60, a shuttle lever sensor 61, an orientation sensor 62, a vehicle speed sensor 63, an arm sensor 64, and a cutting angle sensor 65 are mounted on the tractor.

  As shown in FIGS. 3 and 6, the steering angle sensor 60 is mounted on the handle operating shaft 6a of the steering handle 6 (see FIG. 2), and measures the rotation angle of the handle operating shaft 6a from the reference position. Is detected, and the control device 50 calculates the operation amount (steering operation amount) and the steering speed (steering operation speed) of the steering handle 6. Thereby, the steering angle sensor 60 functions as a steering speed detecting means.

  A shuttle lever sensor 61 is provided at the base of the shuttle lever 35, and the operation position (forward position, neutral position, reverse position) of the shuttle lever 35 can be detected by the shuttle lever sensor 61.

  A vehicle speed sensor 63, which is an example of vehicle speed detection means, is provided in a rotating portion between the auxiliary transmission 23 and the differential mechanism 28 (see FIG. 4), detects the rotation angle of the rotating portion, and controls the control device. 50, the vehicle speed V of the tractor is calculated.

  The direction sensor 62, which is an example of the direction detection means, is disposed at the left and right center portion of the vehicle body 1, and detects the direction of the vehicle body 1 (the traveling direction of the vehicle body 1). An arm sensor 64 that detects the vertical swing angle of the lift arm 8 is provided at the swing portion of the lift arm 8.

  The cutting angle sensor 65 (corresponding to the cutting angle detection means) is mounted on the rotating portion of the knuckle arm 2a linked to the front wheel 2 (see FIG. 2), and determines the cutting angle of the front wheel 2 operated by the steering device 12. To detect. Based on the detection result of the cutting angle sensor 65, the cutting angle of the front wheel 2 is monitored by the control device 50. For example, when the cutting angle of the front wheel 2 changes due to leakage of hydraulic oil in the power cylinder 13, etc. The control device 50 corrects the turning angle of the front wheel 2 based on the detection result from the angle sensor 65, and the accurate turning angle of the front wheel 2 is grasped by the control device 50, and this corrected turning angle of the front wheel 2 will be described later. Control by the control device 50 is performed.

  A mode switch 66 is provided on the left side of the steering handle 6. The mode changeover switch 66 is provided with four switching positions of a two-wheel drive mode, a four-wheel drive mode, a small turning mode, and a sudden turning mode. By switching these four switching positions, the four tractor traveling modes are provided. The mode can be switched.

  When the mode switch 66 is switched to the two-wheel drive mode, the state of the transmission switching device 26 is switched to the front wheel driven state by the output from the control device 50 to the front wheel state switching valve 40, and only the left and right rear wheels 3 are driven. . When the mode selector switch 66 is switched to the four-wheel drive mode, the state of the transmission switching device 26 is switched to the front wheel drive state by the output from the control device 50 to the front wheel state switching valve 40, and the left and right front wheels 2 and the left and right rear wheels are switched. The wheel 7 is driven at a constant speed.

  When the mode selector switch 66 is switched to the small turning mode, when the shuttle lever 35 is operated to the reverse position, the state of the transmission switching device 26 is changed to four by the output from the control device 50 to the front wheel state switching valve 40. By switching to the wheel driving state, the left and right front wheels 2 and the left and right rear wheels 7 are driven at a constant speed.

  When the mode changeover switch 66 is changed to the small turning mode, when the shuttle lever 35 is operated to the forward movement position, the state of the transmission changeover device 26 is changed to four by the output from the control device 50 to the front wheel state changeover valve 40. By switching to the wheel driving state, the left and right front wheels 2 and the left and right rear wheels 7 are driven at a constant speed. Further, when a predetermined condition is satisfied by control by the control device 50 described later, the state of the transmission switching device 26 is switched from the four-wheel drive state to the front wheel acceleration state, so that the left and right front wheels 2 are connected to the left and right rear wheels 3. Drive at an increased speed at a peripheral speed approximately twice the peripheral speed. Thus, the front wheel speed increasing means 51 is configured to drive the front wheel 2 at a peripheral speed approximately twice the peripheral speed of the rear wheel 3 by the output from the control device 50 to the front wheel state switching valve 40.

  When the mode selector switch 66 is switched to the sudden turn mode, when the shuttle lever 35 is operated to the reverse position, the state of the transmission switching device 26 is changed to four by the output from the control device 50 to the front wheel state switching valve 40. By switching to the wheel driving state, the left and right front wheels 2 and the left and right rear wheels 7 are driven at a constant speed.

  When the mode selector switch 66 is switched to the rapid turn mode and the shuttle lever 35 is operated to the forward position, the state of the transmission switching device 26 is changed to four by the output from the control device 50 to the front wheel state switching valve 40. By switching to the wheel driving state, the left and right front wheels 2 and the left and right rear wheels 7 are driven at a constant speed. Further, when a predetermined condition is satisfied by control by the control device 50 described later, the state of the transmission switching device 26 is switched from the four-wheel drive state to the front wheel acceleration state, and the left and right front wheels 2 are rotated around the left and right rear wheels 3. While driving at an increased speed at a circumferential speed that is approximately twice the speed, the side brake 41 inside the turn is operated to the braking side. In this way, by operating the right or left side brake 41 inside the turning to the braking side by the output from the control device 50 to the brake braking switching valve 45, the rear wheel braking means for braking the rear wheel 3 inside the turning. 52 is configured.

  On the right side of the driver's seat 5, an elevating lever 48 is provided so as to be able to swing back and forth, and an elevating lever sensor 67 for detecting the operation position of the elevating lever 48 is provided at the base of the elevating lever 48. Yes. When the elevating lever 48 is operated, the operation position of the elevating lever 48 is set as the target height position, and the target height position, the detected value detected by the arm sensor 64, and the detected value of the arm sensor 64 are used as the actual values of the rotary working device R. Based on the correlation data associated with the height position, the rotary work device R is lifted and lowered to an arbitrary height position corresponding to the operation position of the lift lever 48 from the control device 50 to the lift control valve 47.

  The operation panel 70 is equipped with a plowing depth setting device 71 for setting the plowing depth of the rotary working device R. The rear cover Ra of the rotary working device R is a cover for detecting the vertical swing angle of the rear cover Ra. A sensor 68 is provided. When the lifting lever sensor 67 detects that the lifting / lowering lever 48 has been swung in the floating region provided on the lowest lowered position side of the swinging operation region, the set value of the tilling depth setting unit 71 and the rear portion Based on the detection value of the cover sensor 68 mounted on the cover Ra and the correlation data in which the detection value of the cover sensor 68 is associated with the actual tilling depth of the rotary working device R, the control device 50 moves to the lift control valve 47. It is possible to output and maintain the set tilling depth set by the tilling depth setting unit 71.

  The operation panel 70 is equipped with an upper limit setting device 72 for setting the ascending position (upper limit position) of the rotary working device R.

  A neutrally biased operation lever 49 is provided on the right side of the steering handle 6 so as to swing up and down. An operation lever sensor for detecting the operation position of the operation lever 49 is provided at the base of the operation lever 49. 69 is equipped.

  When the operation lever 49 is swung upward, the set value of the upper limit setter 72, the detected value of the arm sensor 64, and the correlation in which the detected value of the arm sensor 64 is associated with the actual height position of the rotary working device R. Based on the data, it is output from the control device 50 to the lift control valve 47 and the rotary work device R is lifted to the lift position set by the upper limit setter 72.

  When the operating lever 49 is swung downward, and the lift lever 48 is operated outside the floating region, the operation position of the lift lever 48 is set as the target height position, and the target height position and the arm Based on the detection value detected by the sensor 64 and the correlation data in which the detection value of the arm sensor 64 is associated with the actual height position of the rotary working device R, it is output from the control device 50 to the lift control valve 47 to be lifted and lowered. The rotary working device R is lowered to an arbitrary height position corresponding to the operation position of the lever 48.

  When the operation lever 49 is swung downward, and the lift lever 48 is operated in the floating region, the set value of the tilling depth setting device 71 and the cover sensor 68 of the rear cover Ra are set. Based on the detected value and the correlation data in which the detected value of the cover sensor 68 is made to correspond to the actual tilling depth of the rotary working device R, the tilling depth setting device 71 uses the output from the control device 50 to the lifting control valve 47. Automatically descends to the set working depth.

  The operation panel 70 is equipped with an automatic raising switch 73 that can be operated on the entry side (ON) and the cut side (OFF). When the automatic ascending switch 73 is pushed to the entry side (ON), it is determined whether or not the elevating lever 48 is swung within the floating region. When the elevating lever 48 is operated in the floating region, if a predetermined condition is satisfied by control by the control device 50 described later, the set value of the upper limit setter 72, the detected value of the arm sensor 64, and the arm sensor 64 Based on the correlation data in which the detected value is associated with the actual height position of the rotary working device R, the rotary work is set to the raised position set by the upper limit setting device 72 by the output from the control device 50 to the lift control valve 47. The device R is raised automatically. Thus, the automatic raising means 53 that automatically raises the rotary work device R from the lowered position to the raised position is configured by the output from the control device 50 to the elevation control valve 47.

  Note that when the automatic lifting switch 73 is pushed to the cut-off side (OFF), the rotary working device R does not automatically rise, and the rotary working device R is lifted manually by swinging the operating lever 49 upward. Can be made.

  The operation panel 70 is provided with a reverse ascending switch 74 that can be operated on the entry side (ON) and the cut side (OFF). When the reverse ascending switch 74 is pushed to the entry side (ON), it is determined whether or not the elevating lever 48 is swung within the floating region. When the lift lever 48 is operated in the floating area, when the shuttle lever 35 is operated to the reverse position, the set value of the upper limit setting device 72, the detection value of the arm sensor 64, and the arm sensor 64 Based on the correlation data in which the detected value is associated with the actual height position of the rotary work device R, the rotary work is performed up to the lift position set by the upper limit setting device 72 by the output from the control device 50 to the lift control valve 47. The device R is raised automatically.

  The operation panel 70 is equipped with a PTO switch 75. The PTO switch 75 is provided with an on position, a cutting position, and an automatic position. When the PTO switch 75 is switched to the on position, the PTO clutch 29 is operated to the on state by the output from the control device 50 to the PTO state switching valve 46, and when the PTO switch 75 is switched to the off position, the control device 50 switches to the PTO state. By the output to the switching valve 46, the PTO clutch 29 is operated to the disengaged state.

  When the PTO switch 75 is switched to the automatic position, if the grounding of the rotary working device R is detected based on the detection result from the cover sensor 68, the PTO clutch is generated by the output from the control device 50 to the PTO state switching valve 46. 29 is automatically entered and manipulated. When the PTO switch 75 is switched to the automatic position, if the floating of the rotary working device R is detected based on the detection result from the cover sensor 68, the PTO clutch is output by the output from the control device 50 to the PTO state switching valve 46. 29 is automatically turned off.

  A display device 80 (display screen, lamp, buzzer, etc.) is provided on the front side of the steering handle 6. By outputting from the control device 50 to the display device 80, it is displayed on the display screen, the lamp is turned on, Alternatively, visual or audible information can be provided to the driver by sounding a buzzer.

[Calculation method of tractor travel distance and travel distance]
A method of calculating the travel distance W and the travel distances Wx and Wy from the reference position a of the tractor used for work content determination and obstacle avoidance determination described later will be described with reference to FIGS. 6 and 7. FIG. 7 is a schematic plan view illustrating a method of calculating the travel distance W and the travel distances Wx and Wy of the tractor from the reference position a.

  As shown in FIG. 6, since the tractor is provided with an azimuth sensor 62 and a vehicle speed sensor 63, the direction of the vehicle body detected by the azimuth sensor 62 and the vehicle speed V detected by the vehicle speed sensor 63 are determined based on the reference position. 7 with reference to a, a thick line arrow in FIG. 7 is obtained.

  Here, assuming that the tractor is moving on the reference coordinates (x, y) set with reference to the reference position a, the component of the vehicle speed V in the x direction is Vx (= V · cos θ), and the vehicle speed. The component of V in the y direction is Vy (= V · sin θ). When the direction of the vehicle body is changed, the component in the x direction and the component in the y direction of the vehicle speed V are also changed.

  Thus, for example, when the tractor has moved from the reference position a in FIG. 7 to the position b after a predetermined time has elapsed, the component Vx in the x direction of the vehicle speed V within the predetermined time is time-integrated, whereby the tractor reference The movement distance Wx in the x direction from the position a can be calculated. Similarly, the y-direction component Vy of the vehicle speed V within a predetermined time is integrated over time, whereby the movement distance Wy in the y direction from the reference position a of the tractor can be calculated. Further, by integrating the vehicle speed V within a predetermined time with time, the travel distance W of the movement locus from the reference position a to the b position of the tractor indicated by the two-dot chain line in FIG. 7 can be calculated.

  Thereby, the position calculating means 56 for calculating the vehicle body position (W, Wx, Wy) of the tractor from the reference position a is configured.

  In this embodiment, based on the direction of the vehicle body 1 detected by the direction sensor 62 and the vehicle speed V detected by the vehicle speed sensor 63, the travel distance W and the travel distances Wx, Wy are calculated using time integration. Although an example in which the position calculation means 56 for calculating the vehicle body position from the reference position a is shown, the position calculation means 56 for calculating the vehicle body position from the reference position a may be configured by a different calculation method. Further, the vehicle body position of the tractor from the reference position may be calculated based on the tractor travel information detected by the detection means other than the direction sensor 62 and the vehicle speed sensor 63.

  Specifically, for example, although not shown, a GPS antenna and a GPS receiver connected to the GPS antenna are provided so as to receive position information from a GPS satellite and correction information from a reference station, The current position of the tractor may be detected based on the received information, and the vehicle body position of the tractor from the reference position may be calculated. In this case, the GPS receiver may be configured by an SBAS receiver corresponding to SBAS (stationary satellite type satellite navigation augmentation system) so as to be able to receive the correction information for aviation from the reference station.

[Contents of control by control device]
The content of control by the control apparatus 50 is demonstrated based on FIGS. FIG. 8 is a flowchart of the turning mode switching control, and FIG. 9 is a flowchart of the turning determination control. FIG. 10 is a flowchart of travel content determination in the turn determination control, and FIG. 11 is a flowchart of obstacle avoidance determination in the turn determination control.

  FIG. 12 is a graph of threshold value determination in the turning determination control, and is a graph showing the relationship between the vehicle speed V and the threshold value of the steering speed (operation speed) of the steering handle 6. The horizontal axis in FIG. 12 is the vehicle speed V (km / hour), and the vertical axis in FIG. 12 is the steering speed (degrees / second) of the steering handle 6.

  FIG. 13 is a schematic diagram for explaining the first and second predetermined elevation angles α1 and α2 and the first and second predetermined acceleration angles β1 and β2. FIG. 14 is a flowchart when the mode is shifted to the sensitive mode, and FIG. 15 is a flowchart when the mode is shifted to the insensitive mode.

  First, the turning mode switching control will be described with reference to FIG. As shown in FIG. 8, based on the detection result from the mode switch 66, it is determined whether or not the traveling mode is switched to the small turning mode or the sudden turning mode (step # 10). When the traveling mode is switched to the two-wheel drive mode or the four-wheel drive mode, the mode does not shift to any of the sensitive mode and the insensitive mode described later (step # 10, NO).

  Note that step # 10 may be abolished and the flow after step # 11 may be executed regardless of which mode the traveling mode is switched to. In this case, it may be configured to determine whether or not the traveling mode is switched to the small turning mode or the sudden turning mode in Step # 64 of FIG. 14 and Step # 74 of FIG.

  When the traveling mode is switched to the small turning mode or the sudden turning mode (step # 10, YES), whether or not the shuttle lever 35 is operated to the forward position based on the detection result from the shuttle lever sensor 61. Is determined (step # 11). When the shuttle lever 35 is operated to the forward position (step # 11, YES), whether or not the PTO clutch 29 is operated to the engaged state depending on the output state from the control device 50 to the PTO state switching valve 46. Judgment is made (step # 12).

  Next, when the PTO clutch 29 is operated in the engaged state (step # 12, YES), the vehicle speed V is within a preset working speed range (for example, 0. 0) based on the detection result from the vehicle speed sensor 63. Between 2 and 5.0 km / h).

  When the shuttle lever 35 is not operated to the forward position (step # 11, NO), when the PTO clutch 29 is operated in the disengaged state (step # 12, NO), and when the vehicle speed V is outside the working speed range. In some cases (step # 13, NO), the mode is controlled so as not to shift to any of the sensitive mode and the insensitive mode, which will be described later, and thereby the checking means for checking the transition to the sensitive mode and the insensitive mode. Is configured.

  That is, when any one of these conditions (steps # 11 to # 13) is not satisfied, the tractor is in a state where it is not plowing (in a state where there is a high possibility that it is not plowing). Therefore, by checking the transition to the sensitive mode and the insensitive mode in such a state, the automatic lifting means 53, the front wheel speed increasing means 51, even though the tractor is not plowing work, In addition, it is possible to prevent the rear wheel braking means 52 from operating.

  It should be noted that the transition to the sensitive mode and the insensitive mode may be controlled by any one or more of the conditions of steps # 11 to # 13, and the conditions of steps # 11 to # 13 are different. You may comprise so that it may perform in order.

  Moreover, if it is a condition that can determine that the tractor is not plowing (if it is highly possible that the plow is not plowing), a different condition is used instead of the conditions of steps # 11 to # 13. For example, when a rotational speed detecting means (not shown) for detecting the rotational speed of the engine 19 is provided and the rotational speed of the engine 19 is not the rotational speed during the tillage operation, the sensitive mode and the insensitive mode are entered. For example, when a traction load is small or a traction load is not detected, a load detection means (not shown) for detecting a traction load by the rotary working device R may be provided. The transition to the sensitive mode and the insensitive mode may be suppressed.

  Next, when the vehicle speed V is within the working speed range (step # 13, YES), it is determined whether or not the automatic ascent switch 73 is pushed to the on side (ON) (step # 14). When the automatic raising switch 73 is pushed to the cutting side (OFF) (step # 14, NO), the tractor turning mode is sensitive without shifting to the turning determination control (step # 15) described later. Switch to mode.

  If the automatic ascending switch 72 is pushed to the entry side (ON) (step # 14, YES), whether or not the tractor is in a turning operation state by the turning determination control described later ("turning"). ), It is determined whether or not the state is in a turning operation state ("non-turning") (step # 15).

  When the tractor state is determined to be “turning” by turning determination control described later (step # 15, turning), the tractor turning mode is switched to a sensitive mode (step # 16), and the tractor turning control described later is performed. If it is determined that the state is “non-turning” (step # 15, non-turning), the turning mode of the tractor is switched to the insensitive mode (step # 17).

  Here, “sensitive” in the sensitive mode means that the operation sensitivity to the operation of the steering handle 6 is good, and the automatic raising means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 correspond to the operation of the steering handle 6. This means that the operation is easy (sensitive), and the “insensitivity” in the insensitive mode means that the operation sensitivity to the operation of the steering handle 6 is poor, and the automatic raising means 53, the front wheel acceleration for the operation of the steering handle 6 It means that the means 51 and the rear wheel braking means 52 are difficult to operate (insensitive).

  Next, the turning determination control will be described with reference to FIGS. As shown in FIG. 9, in the turning determination control, the travel content determination (step # 20, FIG. 10), the obstacle avoidance determination (step # 21, FIG. 11), and the threshold determination (step # 22, FIG. 12) has been implemented.

  First, the travel content determination will be described based on FIGS. 9 and 10. As shown in FIG. 10, in the travel content determination, it is estimated whether or not the travel of the tractor is the alignment travel with respect to the work travel route of the vehicle body by the estimation means 54 of the control device 50 (step # 30). Here, the estimation of whether or not the alignment traveling with respect to the work traveling route is estimated as follows, for example.

  For example, when it is detected that the shuttle lever 35 is operated to the forward movement position based on the detection result from the shuttle lever sensor 61, it is presumed that the traveling of the tractor is alignment (step # 30). YES) That is, when the shuttle lever 35 is operated to the forward movement position to advance immediately after the vehicle body 1 is moved backward, there is a high possibility that the tilling work is started, and the vehicle is aligned with the work travel route. Since there are many cases (for example, the alignment work immediately after the start (see FIG. 19C)), it is estimated that the tractor travel is the alignment travel.

  In this case, it may be detected that the vehicle is moving forward immediately after the vehicle body 1 is moved backward by different detection means. For example, the shift position detection means for detecting the shift position (shift stage number) of the vehicle speed sensor 63 and the main transmission 21. (Not shown) or based on a detection result from a lever sensor (not shown) for detecting the operation position of the main transmission lever 32, it is detected that the vehicle is moving forward immediately after the vehicle body 1 is moved backward, and the tractor It may be configured such that the traveling of the tractor is estimated to be the alignment traveling, or a combination of these detection means may be configured to infer that the traveling of the tractor is the alignment traveling. .

  Further, for example, when it is detected that the rotary work device R has been raised to the raised position set by the upper limit setting device 72 based on the detection result from the arm sensor 64, the traveling of the tractor is the alignment traveling. (Step # 30, YES). That is, when the rotary working device R is raised and the tilling work is temporarily interrupted, there is a high possibility that the turn to the adjacent traveling route (adjacent tilling) has ended, and the alignment traveling with respect to the working traveling route is performed. Therefore, it is presumed that the traveling of the tractor is the alignment traveling (for example, the alignment work immediately after turning (see FIG. 19D)).

  In this case, the rise of the rotary working device R may be detected by different detection means. For example, the output state from the control device 50 to the lift control valve 47, the output state from the control device 50 to the PTO state switching valve 46, the cover A configuration may be adopted in which the rise of the rotary working device R is detected based on the detection result from the sensor 68 or the detection result from the operation lever sensor 69, and the tractor travel is estimated to be the alignment travel. It is also possible to use a combination of these detection means so that the traveling of the tractor is estimated to be the alignment traveling.

  If it is presumed that the tractor travel is an alignment travel (step # 30, YES), the reference position a for calculating the travel distance W of the tractor is set (step # 31). Then, the calculation of the travel distance W of the tractor from the reference position a is started by the above-described calculation method of the travel distance W. The timing for setting the reference position a may be, for example, when the operation of the shuttle lever 35 to the forward position is detected, or when the lift of the rotary working device R is detected to the raised position. It may be after a predetermined time (for example, 0.2 seconds) from the time point or after step # 32.

  If it is presumed that the tractor travel is the alignment travel (step # 30, YES), it is determined that the tractor travel is the alignment travel (step # 32, step # 20, the alignment travel). Thereby, the state of the tractor is determined to be “non-turning” (step # 24), and the turning mode of the tractor is switched to the insensitive mode (step # 15, non-turning, step # 17).

  Next, it is determined whether or not the tractor travel distance W from the reference position a is equal to or greater than a predetermined distance (for example, 2 m) set in advance (step # 33). When the travel distance W of the tractor from the reference position a is less than the predetermined distance (step # 33, NO), the state where it is determined that the travel of the tractor is the alignment travel is maintained (step # 33, NO, step # 32).

  When the travel distance W of the tractor from the reference position a is equal to or greater than the predetermined distance (step # 33, YES), the travel distance W of the tractor from the reference position a is reset to the initial value (0 m) (step # 34). It is determined that the traveling of the tractor is turning (step # 35, step # 20, turning). Thereby, it is determined that the vehicle is not avoided by the obstacle avoidance determination described later (step # 21, non-avoidance), and when the steering speed of the steering handle 6 is determined to be equal to or higher than the threshold value by the threshold determination (step # 22 · YES), the state of the tractor is determined to be “turning” (step # 23), and the turning mode of the tractor is switched to the sensitive mode (step # 15, turning, step # 16).

  The reference coordinates (x, y) at the reference position a are set, the movement distance Wx or the movement distance Wy from the reference position a is calculated, and the movement distance Wx or the movement distance Wy from the reference position a is set in advance. When the predetermined distance is exceeded, the tractor moving distance Wx or the moving distance Wy may be reset to the initial value (0 m).

  When it is determined that the tractor travel is not the alignment travel (step # 30, NO), it is determined that the tractor travel is the turning travel, and is determined to be the alignment travel. The tractor travel remains in the state determined to be turning (step # 20, turning travel) except for the period from the time until it is determined that the vehicle is turning.

  Next, the obstacle avoidance determination will be described with reference to FIG. 9, FIG. 11, and FIG. As shown in FIG. 11, in the obstacle avoidance determination, based on the detection result from the turning angle sensor 65, it is determined whether or not the turning angle of the front wheel 2 from the straight traveling position is greater than or equal to a predetermined turning angle e set in advance. (Step # 40). As described above, the operation start determining means 55 is configured to determine the start of the operation of the steering handle 6 in the obstacle avoiding direction based on the detection result from the turning angle sensor 65.

  As shown in FIG. 13, the predetermined turning angle e is an angle (for example, 2 to 3 degrees) at which the turning angle of the front wheel 2 is changed from the straight traveling position due to unevenness of the field or fine adjustment of the steering handle 6 during straight traveling. A larger angle (for example, 4 degrees or 5 degrees) is set. Thereby, only when there is a high possibility of obstacle avoidance, it is possible to shift to the subsequent control (steps # 41 to # 50), and the obstacle avoidance determination can be performed efficiently at an appropriate timing.

  The predetermined cutting angle e may be set to a different large angle or a small angle, and the predetermined cutting angle from the straight traveling position to the left side and the predetermined cutting angle from the straight driving position to the right side are set to different angles (magnitude relationship). May be.

  Further, in this embodiment, an example in which the predetermined turning angle e is set with the straight traveling position as the reference position is shown. However, the position where the cutting angle of the front wheel 2 is operated to the right or left from the straight traveling position by the predetermined angle is set as the reference position. A cutting angle e may be set. Further, the change angle of the front wheel 2 to be changed is detected every predetermined time, the detected position of the front wheel 2 is set as a reference position, and the predetermined turn angle from the reference position is set every predetermined time. You may comprise.

  As shown in FIG. 11, when it is determined that the turning angle of the front wheel 2 is equal to or greater than the predetermined turning angle e (step # 40 · YES), based on the detection result from the direction sensor 62, the front wheel 2 from the straight traveling position The extension line of the direction of the vehicle body 1 detected by the azimuth sensor 62 at the time of the determination that the turning angle is equal to or greater than the predetermined turning angle e is set as the reference line L (step # 41).

  Next, a reference position a for calculating the movement distances Wx and Wy of the tractor is set (step # 42), and the position calculation means 56 of the control device 50 uses the calculation method of the movement distances Wx and Wy described above. Based on the detection results from the azimuth sensor 62 and the vehicle speed sensor 63, the tractor moving distance Wy from the reference line L in the direction orthogonal to the reference line L and the reference position a in the direction toward the reference line L. Calculation of the movement distance Wx of the tractor is started. Note that the timing for setting the reference position a may be a point in time when it is determined that the turning angle of the front wheel 2 is equal to or greater than the predetermined cutting angle e, and the cutting angle of the front wheel 2 is determined to be equal to or larger than the predetermined cutting angle e. It may be after a predetermined time (for example, 0.2 seconds) has elapsed from the time of being performed.

  Here, it is determined whether the tractor movement distance Wy from the reference line L in the direction orthogonal to the reference line L is opposite to the direction of the turning angle of the front wheel 2 with respect to the reference line L (reference Determination of whether the vehicle body position of the tractor is located in the right direction or the left direction with respect to the reference line L when viewed from the position a) (step # 44), and the reference in the direction in which the reference line L faces The movement distance Wx of the tractor from the position a is used to determine whether to reset the reference line L, the reference position a, and the movement distances Wx and Wy (step # 49).

  Next, based on the detection result from the turning angle sensor 65, it is determined whether or not the steering handle 6 has been operated in the direction opposite to the obstacle avoiding direction (step # 43). Here, for example, when the obstacle avoidance direction is the left direction and the turning angle of the front wheel 2 is determined to be greater than or equal to the predetermined turning angle e by operating the steering handle 6 in the left direction (step # 40 YES) ), It is determined whether or not the steering handle 6 has been operated in the right direction opposite to the obstacle avoiding direction. For example, the obstacle avoiding direction is in the right direction and the front handle 2 is operated by operating the steering handle 6 in the right direction. If it is determined that the turning angle is equal to or greater than the predetermined turning angle e (step # 40, YES), it is determined whether or not the steering handle 6 has been operated in the left direction opposite to the obstacle avoiding direction.

  If it is determined that the steering handle 6 has been operated in the direction opposite to the obstacle avoiding direction (step # 43, YES), the tractor moving distance Wy from the reference position a in the direction orthogonal to the reference line L is cut off. Depending on the turning angle of the front wheel 2 detected by the angle sensor 65, the direction of the vehicle body position relative to the reference line L (either the direction of the vehicle body position of the tractor rightward or leftward relative to the reference line L when viewed from the reference position a) It is determined whether or not the direction of the turning angle of the front wheel 2 from the straight traveling position is opposite (step # 44).

  Here, for example, when the left direction (y direction) orthogonal to the reference line L is set to be positive, the vehicle body position relative to the reference line L while the tractor movement distance Wy from the reference position a shows a positive value. Is the left direction, and when the movement distance Wy of the tractor from the reference position a turns to a negative value, the direction of the vehicle body position with respect to the reference line L is the right direction. When the tractor movement distance Wy from the reference position a is zero, the vehicle body position is located on the reference line L. In this state, the tractor movement distance Wy from the reference position a is positive. It is handled in the same way as when the value of is shown.

  If it is determined that the direction of the vehicle body position with respect to the reference line L and the direction of the turning angle of the front wheel 2 are opposite (step # 44, YES), the operation of the steering handle 6 is accompanied by avoiding an obstacle. It is determined that there is (step # 45, step # 21, avoidance). Thereby, the state of the tractor is determined to be “non-turning” (step # 24), and the turning mode of the tractor is switched to the insensitive mode (step # 15, non-turning, step # 17).

  In this case, when it is determined that the direction of the vehicle body position with respect to the reference line L and the direction of the turning angle of the front wheel 2 are opposite directions, it is determined that the operation of the steering handle 6 is accompanied by avoidance of an obstacle. A predetermined time (for example, 0.2 seconds) set in advance after it is determined that the direction of the vehicle body position with respect to the reference line L and the direction of the turning angle of the front wheel 2 are opposite to each other. ) After the elapse of time, it may be configured that it is determined that the operation of the steering handle 6 is accompanied by the avoidance of the obstacle.

  As described above, the operation start determining means 55 determines the start of the operation to the right or left side of the steering handle 6, and after the start of this operation is determined, the steering handle 6 is moved to the other side of the right or left side. (Step # 43), it is determined that, under certain conditions (step # 44), it is determined that the operation of the steering handle 6 is accompanied by avoiding an obstacle (step # 44). # 45).

  Next, it is determined whether or not the moving distance Wx of the tractor from the reference position a is equal to or larger than a predetermined distance (for example, 6 m) set in advance (step # 47), and the cutting angle of the front wheel 2 is set to the predetermined cutting angle e. It is determined whether or not it has become less than (step # 48). If the moving distance Wx of the tractor from the reference position a is less than the predetermined distance (step # 47, NO), or the moving distance Wx of the tractor from the reference position a is greater than or equal to the predetermined distance but the cutting angle of the front wheel 2 is In the case where the angle is equal to or greater than the predetermined turning angle e (step # 48, NO), the state where the steering handle 6 is operated in the direction opposite to the obstacle avoiding direction is maintained (step # 43, YES), and the reference line L If the state where the direction of the vehicle body position with respect to the direction of the turning angle of the front wheel 2 is opposite is maintained (YES in step # 44), it is determined that the operation of the steering handle 6 involves avoiding an obstacle. The maintained state is maintained (step # 45).

  When the steering handle 6 is not operated in the direction opposite to the obstacle avoiding direction (step # 43, NO), and when the steering handle 6 is operated again in the same direction as the obstacle avoiding direction (step #). 47 · NO or step # 48 · NO, step # 43 · NO), it is determined that the operation of the steering handle 6 is not accompanied by avoiding the obstacle (step # 46, step # 21, non-avoidance). As a result, if it is determined by threshold determination described later that the steering speed of the steering handle 6 is equal to or higher than the threshold (step # 22, YES), the tractor state is determined to be “turning” (step #). 23) The turning mode of the tractor is switched to the sensitive mode (step # 15, turning, step # 16).

  When the direction of the vehicle body position with respect to the reference line L is not opposite to the direction of the turning angle of the front wheel 2 (step # 44 NO), and the direction of the vehicle body position with respect to the reference line L and the turning angle of the front wheel 2 When the direction is the same again (step # 47, NO or step # 48, NO, step # 43, YES, step # 44, NO), the operation of the steering handle 6 is accompanied by avoiding the obstacle. It is determined that it is not a thing (step # 46, step # 21, non-avoidance). As a result, if it is determined by threshold determination described later that the steering speed of the steering handle 6 is equal to or higher than the threshold (step # 22, YES), the tractor state is determined to be “turning” (step #). 23) The turning mode of the tractor is switched to the sensitive mode (step # 15, turning, step # 16).

  Whether it is determined that the operation of the steering handle 6 is accompanied by avoiding the obstacle (step # 45), or whether the operation of the steering handle 6 is not accompanied by avoiding the obstacle (step # 46). Regardless, the moving distance Wx of the tractor from the reference position a is equal to or greater than a predetermined distance set in advance (step # 47, YES), and the turning angle of the front wheel 2 is less than the predetermined turning angle e (step # 48, YES), the reference position a, the reference line L, and a turning angle to be described later are reset, and the tractor movement distances Wx and Wy from the reference position a are reset to initial values (0 m) (step # 49).

  It is also possible to calculate the tractor travel distance W from the reference position a and reset the tractor travel distance W to an initial value (0 m) when the travel distance W is equal to or greater than a predetermined distance. Good.

  If it is determined that the operation of the steering handle 6 is accompanied by avoiding the obstacle, it is determined that the operation of the steering handle 6 is not accompanied by avoiding the obstacle (step # 50, Step # 21, non-avoidance). As a result, if it is determined by threshold determination described later that the steering speed of the steering handle 6 is equal to or higher than the threshold (step # 22, YES), the tractor state is determined to be “turning” (step #). 23) The turning mode of the tractor is switched to the sensitive mode (step # 15, turning, step # 16).

  If it is not determined that the turning angle of the front wheel 2 is equal to or greater than the predetermined turning angle e (step # 40, NO), it is determined that the operation of the steering handle 6 is not accompanied by avoiding an obstacle. (Step # 21, non-avoidance).

  Next, threshold value determination of the steering speed of the steering handle 6 will be described based on FIG. 9 and FIG. As shown in FIG. 12, as the vehicle speed V increases, the steering speed of the steering handle 6 with respect to the vehicle speed V increases so that the threshold of the steering speed of the steering handle 6 increases linearly in proportion to the increase in the vehicle speed V. A threshold value of the steering speed is set. In FIG. 12, the threshold value of the steering speed of the steering handle 6 with respect to the vehicle speed V is shown as a threshold line K.

  In the high speed region of the threshold line K, there is provided an upper limit portion Ka where the steering speed threshold value of the steering handle 6 becomes constant. In the high speed region where the vehicle speed V is relatively high, the vehicle speed V increases. Is configured so that the threshold value is not changed regardless. As a result, it is possible to prevent the steering handle 6 from being judged as non-turning despite the fact that the steering handle 6 has been operated quickly because the threshold of the steering speed of the steering handle 6 with respect to the vehicle speed V is too high.

  Accordingly, the vehicle speed V detected by the vehicle speed sensor 63 and the steering speed of the steering handle 6 detected by the steering angle sensor 60 are plotted in FIG. 12, and the plotted point falls within the upper region of the threshold line K. It is determined that the steering speed of the steering handle 6 is equal to or higher than the threshold value (including on the threshold line K) (step # 22, YES). Thereby, the state of the tractor is determined as “turning” (step # 23), and the turning mode of the tractor is switched to the sensitive mode (step # 15, turning, step # 16).

  On the other hand, the vehicle speed V detected by the vehicle speed sensor 63 and the steering speed of the steering handle 6 detected by the steering angle sensor 60 are plotted in FIG. 12, and the plotted point falls in the lower region of the threshold line K. It is determined that the steering speed of the steering handle 6 is less than the threshold value (except for the threshold line K) (step # 22, NO). Thereby, the state of the tractor is determined to be “non-turning” (step # 24), and the turning mode of the tractor is switched to the insensitive mode (step # 15, non-turning, step # 17).

  Here, for example, when traveling along a reed in a deformed field where the reed is curved or when traveling straight on a farm field, the revolving handle 6 is often operated at a relatively high speed and the control handle 6 is operated relatively slowly. In many cases, the vehicle speed V is high and the steering speed is low, so that it easily enters the lower region of the threshold line K with a high probability. Therefore, the turning mode of the tractor is easily switched to the insensitive mode, and the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 are difficult to operate as will be described later.

  On the other hand, for example, when headland turns (turning about 180 degrees at the shore), the vehicle is often driven at a relatively low speed, and the steering handle 6 is often operated relatively quickly. It becomes easy to enter the upper region of the threshold line K with a high probability of being slow and having a high steering speed. Therefore, the turning mode of the tractor is easily switched to the sensitive mode, and the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 are easily operated as will be described later.

  Next, based on FIG. 13, the first and second predetermined rising angles α1 and α2 (corresponding to the predetermined angle), and the first and second used when the turning mode is switched to the insensitive mode and the sensitive mode. The predetermined acceleration angles β1 and β2 (corresponding to the predetermined angle) will be described.

As shown in FIG. 13, the first predetermined rising angle α1 and the first predetermined acceleration angle β1 are based on the straight traveling position (the vertical position in FIG. 13 ) where the traveling direction of the vehicle body and the front wheel 2 are substantially parallel . Is set as

  The first predetermined acceleration angle β1 is set to an angle larger than the first predetermined increase angle α1, and the second predetermined acceleration angle β2 is set to an angle larger than the second predetermined increase angle α2.

  Here, for example, the first predetermined rising angle α1 is set to a position where the turning angle of the front wheel 2 is operated 33 degrees to the right from the straight traveling position, and the cutting angle of the front wheel 2 is operated 33 degrees to the left from the straight traveling position. Is set to the correct position. Further, for example, the second predetermined rising angle α2 is set to a position where the turning angle of the front wheel 2 is operated 50 degrees to the right from the straight traveling position, and the turning angle of the front wheel 2 is operated 50 degrees to the left from the straight traveling position. Set to position.

  Further, for example, the first predetermined acceleration angle β1 is set to a position where the turning angle of the front wheel 2 is operated 35 degrees to the right from the straight traveling position, and the cutting angle of the front wheel 2 is operated 35 degrees to the left from the straight traveling position. Is set to the correct position. Further, for example, the second predetermined acceleration angle β2 is set to a position where the turning angle of the front wheel 2 is operated 52 degrees to the right from the straight position, and the turning angle of the front wheel 2 is operated 52 degrees to the left from the straight position. Is set to the correct position.

  The angle difference between the first and second predetermined rising angles α1, α2 is set to the same angle as the angle difference between the first and second predetermined acceleration angles β1, β2.

  Next, based on FIG. 8, FIG. 14, and FIG. 15, the control when the turning mode of the tractor is switched to the sensitive mode and the insensitive mode will be described. As shown in FIGS. 8 and 14, when the turning mode of the tractor is switched to the sensitive mode (step # 16), the turning angle of the front wheel 2 is set to the first predetermined rising angle based on the detection result from the turning angle sensor 65. It is determined whether or not α1 or more (step # 60).

  As shown in FIG. 14, when the turning angle of the front wheel 2 becomes equal to or greater than the first predetermined rising angle α1 (step # 60, YES), the automatic lifting means 53 automatically raises the rotary working device R from the lowered position to the raised position. (Step # 61). When the turning angle of the front wheel 2 is less than the first predetermined rising angle α1, the process does not proceed to the next flow (step # 60, NO).

  Next, based on the detection result from the turning angle sensor 65, it is determined whether or not the turning angle of the front wheel 2 is equal to or greater than the first predetermined acceleration angle β1 (step # 62). When the turning angle of the front wheel 2 becomes equal to or greater than the first predetermined acceleration angle β1 (step # 62, YES), the state of the transmission switching device 26 is switched to the front wheel acceleration state by the front wheel acceleration means 51, and the front wheel 2 is moved to the rear. The drive is increased at a peripheral speed approximately twice the peripheral speed of the wheel 3 (step # 63). When the turning angle of the front wheel 2 is less than the first predetermined acceleration angle β1, the process does not proceed to the next flow (step # 62, NO).

  Next, based on the detection result from the mode switch 66, it is determined whether the traveling mode is switched to the small turning mode or the sudden turning mode (step # 64). When the traveling mode is switched to the sudden turn mode (step # 64, sudden turn), the rear wheel braking means 52 operates the right or left side brake 41 inside the turn to the braking side (step #). 65). Then, although not shown, if it is determined that the vehicle body has turned about 180 degrees since the start of turning based on the detection result from the direction sensor 62, the operation of the front wheel acceleration means 51 is automatically released. The state of the transmission switching device 26 is switched to the four-wheel drive state, and the operation of the rear wheel braking means 52 is automatically released to release the operation of the side brake 41 on the inside of the turn to the braking side. ing.

  When the running mode is switched to the small turning mode (step # 64, small turning), although not shown, the vehicle turns about 180 degrees after the vehicle starts turning based on the detection result from the direction sensor 62. If it is determined that the operation has been performed, the operation of the front wheel acceleration means 51 is automatically released, and the state of the transmission switching device 26 is switched to the four-wheel drive state.

  As shown in FIGS. 8 and 15, when the turning mode of the tractor is switched to the insensitive mode (step # 17), the turning angle of the front wheel 2 is set to the second predetermined rising angle based on the detection result from the turning angle sensor 65. It is determined whether or not α2 or more (step # 70).

  As shown in FIG. 15, when the turning angle of the front wheel 2 becomes equal to or greater than the second predetermined rising angle α2 (step # 70 YES), the automatic lifting means 53 automatically lifts the rotary working device R from the lowered position to the raised position. (Step # 71). When the turning angle of the front wheel 2 is less than the second predetermined rising angle α2, the process does not proceed to the next flow (step # 70, NO).

  Since the second predetermined rising angle α2 is set to be larger than the first predetermined rising angle α1, the turning angle of the front wheel 2 is equal to or greater than the first predetermined rising angle α1 when the tractor turning mode is shifted to the insensitive mode. Even in this case, the automatic lifting means 53 does not operate unless the turning angle of the front wheel 2 becomes equal to or greater than the second predetermined rising angle α2. Thus, there is configured a control means for controlling the automatic raising means 53 not to operate when the turning angle of the front wheel 2 becomes equal to or larger than the first predetermined rising angle α1.

  Next, based on the detection result from the turning angle sensor 65, it is determined whether or not the turning angle of the front wheel 2 is equal to or greater than the second predetermined acceleration angle β2 (step # 72). When the turning angle of the front wheel 2 becomes equal to or greater than the second predetermined acceleration angle β2 (step # 72, YES), the state of the transmission switching device 26 is switched to the front wheel acceleration state by the front wheel acceleration means 51, and the front wheel 2 is moved to the rear. Driving is increased at a circumferential speed approximately twice the circumferential speed of the wheel 3 (step # 73). If the turning angle of the front wheel 2 is less than the second predetermined acceleration angle β2, the process does not proceed to the next flow (step # 72, NO).

  Next, based on the detection result from the mode switch 66, it is determined whether the traveling mode is switched to the small turning mode or the sudden turning mode (step # 74). When the traveling mode is switched to the sudden turn mode (step # 74, sudden turn), the rear wheel braking means 52 operates the right or left side brake 41 inside the turn to the braking side (step #). 75). Although not shown, if it is determined based on the detection result from the direction sensor 62 that the vehicle body 1 has turned about 180 degrees since the start of turning, the operation of the front wheel acceleration means 51 is automatically released. Thus, the state of the transmission switching device 26 is switched to the four-wheel drive state, and the operation of the rear wheel braking means 52 is automatically released to release the operation of the side brake 41 on the inside of the turn to the braking side. Has been.

  Since the second predetermined acceleration angle β2 is set to an angle larger than the first predetermined acceleration angle β1, the turning angle of the front wheel 2 is set to the first predetermined acceleration when the tractor turning mode has shifted to the insensitive mode. Even if the angle β1 or more, the front wheel acceleration means 51 and the rear wheel braking means 52 do not operate unless the turning angle of the front wheel 2 becomes the second predetermined acceleration angle β2 or more. Thereby, when the turning angle of the front wheel 2 becomes equal to or greater than the first predetermined acceleration angle β1, the front wheel acceleration means 51 and the rear wheel braking means 52 are configured not to operate.

  When the traveling mode is switched to the small turning mode (step # 74, small turning), although not shown, based on the detection result from the direction sensor 62, the vehicle body 1 starts turning about 180 degrees. When it is determined that the vehicle has made a turn, the operation of the front wheel speed increasing means 51 is automatically released and the state of the transmission switching device 26 is switched to the four-wheel drive state.

[Avoidance status by obstacle avoidance judgment]
The avoidance situation of the obstacle S by the obstacle avoidance determination will be described with reference to FIGS. FIG. 16 is a schematic plan view for explaining the avoidance situation of the obstacle S, and the arrow shown by a thick line in FIG. 16 is the operation direction of the steering handle 6 at the movement points A to I of the tractor. FIG. 17 is a table showing the status of each parameter at the tractor movement points A to I in FIG. 16, and FIG. 18 is a schematic plan view for explaining the work status when the obstacle S is avoided. The “turning angle” in FIG. 17 indicates whether the direction of the vehicle body 1 detected by the azimuth sensor 62 at the tractor movement points A to I is right or left with respect to the direction of the reference line L. Is.

  16-18, the case where the steering handle 6 is operated to the left to avoid the obstacle S, that is, the case where the obstacle avoiding direction is the left direction will be described as an example. In the case where the direction is the right side, the same action is performed by mistake. Moreover, the setting of the obstacle S and the field shown in FIGS. 16 to 18 is shown as an example, and can be similarly applied to other obstacles that exist in the field. Even in the case where there is, the same applies.

  As shown in FIGS. 16 and 17, the point A is a state where the rotary working device R is plowing the field at the shore while moving the tractor along the ridge, and the mode changeover switch 66 is in the small turning mode. Or, it is switched to the sudden turning mode, the rotary working device R is lowered to the set tilling depth set by the tilling depth setting device 71, the PTO clutch 29 is operated to the engaged state, and the automatic raising switch 73 is turned on (ON). It is a state in which a push operation is performed (a state in which a tilling operation is performed along the edge).

  At point A, the turning angle of the front wheel 2 detected by the turning angle sensor 65 is substantially zero degrees, and the direction of the vehicle body 1 detected by the azimuth sensor 62 is substantially parallel to the heel.

  In order to avoid the obstacle S, while operating the steering handle 6 to the left side, the tractor is driven from point A to point B, and the cutting angle of the front wheel 2 detected by the cutting angle sensor 65 is greater than or equal to a predetermined cutting angle e. Then, the direction of the vehicle body 1 detected by the azimuth sensor 62 when the turning angle of the front wheel 2 reaches the predetermined turning angle e is set as the determination reference direction, and the extension line of the determination reference direction is a point in FIG. It is set as a reference line L indicated by a chain line.

  Further, the vehicle body position of the tractor at the time when the turning angle of the front wheel 2 reaches the predetermined turning angle e (point B) is set as the reference position a, and the direction in which the reference line L faces from the reference position a (x direction) The calculation of the tractor movement distance Wx and the tractor movement distance Wy in the direction (y direction) orthogonal to the reference line L from the reference position a is started by the above-described calculation method of the movement distances Wx and Wy. . In FIG. 16, the reference position a is set with reference to the central portion of the tractor, and the reference coordinates (x, y) in the above-described method of calculating the moving distances Wx and Wy are the central portion of the tractor at the point B. Is set as a standard.

  The tractor at point C is in a state where the steering handle 6 is further operated to the left side in order to avoid the obstacle S. The tractor at point D is in a state in which the steering handle 6 has started to be operated to the right. At point D, the turning angle is zero degrees, and the direction of the vehicle body 1 is substantially parallel to the direction of the reference line L. State. When an operation to the right side of the steering handle 6 at this point D is detected by the steering angle sensor 60, it is determined that the operation to the right side of the steering handle 6 at this point D is due to the avoidance of the obstacle S. Thus, the turning mode is switched to the insensitive mode.

  Since the turning mode remains in the sensitive mode between the points A and C, the front wheel 2 is operated by further operating the steering handle 6 to the left from the point C as shown in FIG. When the turning angle is equal to or greater than the first predetermined rising angle α1, when the mode changeover switch 66 is switched to the small turning mode or the sudden turning mode, the rotary working device R automatically rises, and further, the front wheel 2 When the turning angle becomes equal to or greater than the first predetermined acceleration angle β1, the state of the transmission switching device 26 is switched to the front wheel acceleration state. Further, when the mode switch 66 is switched to the sudden turn mode, when the turning angle of the front wheel 2 becomes equal to or greater than the first predetermined acceleration angle β1, the side brake 41 on the inside (left side) of the turn is operated to the braking side. Is done.

  In order to avoid contact between the rotary work device R and the obstacle S, the tractor at the point E operates the steering handle 6 to the right side so that the direction of the vehicle body 1 is substantially parallel to the side wall of the obstacle S. The tractor at point F is a state in which the steering handle 6 is further operated to the right side.

In the state from the point B to the point F, the vehicle body position of the tractor is located on the left side of the reference line L (upper side in the drawing of FIG. 16), the steering handle 6 is operated to the right side, and the turning angle of the front wheel 2 is rightward Therefore, it is determined that the operation to the right side of the steering handle 6 in the state from the point D to the point F is accompanied by the avoidance of the obstacle S.

  The tractor at point G is in a state where the steering handle 6 is operated to the left so that the obstacle S is avoided and the direction of the vehicle body 1 is parallel to the heel. At point G, the vehicle body position of the tractor is located on the right side of the reference line L (lower side of the drawing in FIG. 16), and the steering handle 6 is operated to the left side so that the turning angle of the front wheel 2 is leftward. It is determined that the operation on the left side of the steering handle 6 is accompanied by avoidance of the obstacle S.

  As described above, when it is determined that the operation of the steering handle 6 is accompanied by the avoidance of the obstacle S, the turning mode of the tractor is switched to the insensitive mode, and the first predetermined increase angle α1 is increased by the second predetermined increase. The first predetermined acceleration angle β1 is greatly changed to the second predetermined acceleration angle β2 and the automatic ascending means 53, front wheel acceleration means 51, and rear wheel braking means 52 are operated. Be delayed. Therefore, for example, even if the turning angle of the front wheel 2 detected by the turning angle sensor 65 becomes equal to or greater than the first predetermined rising angle α1 at points D to G, the automatic lifting means 53 does not operate (the rotary working device R is lifted). Even if the turning angle of the front wheel 2 detected by the turning angle sensor 65 becomes equal to or greater than the first predetermined acceleration angle β1 at the points D to G, the front wheel acceleration means 51 and the rear wheel braking means 52 operate. do not do.

  As shown by (F ′) in FIG. 16, when the steering handle 6 is further operated to the right side from the point F, the vehicle body position of the tractor is positioned on the right side (lower side of the drawing in FIG. 16) with respect to the reference line L. Is operated to the right side, and the turning angle of the front wheel 2 is rightward, so that it is determined that the operation of the steering handle 6 is not accompanied by the obstacle avoidance, and the turning mode is switched to the sensitive mode. Accordingly, when the steering handle 6 is further operated to the right side from the point F and the turning angle of the front wheel 2 becomes equal to or larger than the first predetermined ascending angle α1, the mode switch 66 is switched to the small turning mode or the sudden turning mode. In this case, when the rotary work device R is automatically raised and the turning angle of the front wheel 2 becomes equal to or greater than the first predetermined acceleration angle β1, the state of the transmission switching device 26 is switched to the front wheel acceleration state. Further, when the mode switch 66 is switched to the sudden turn mode, the side brake 41 on the inner side (right side) of the turn is operated to the braking side when the turning angle of the front wheel 2 becomes equal to or greater than the first predetermined acceleration angle β1. Is done.

  The tractor at the point H gradually returns the steering handle 6 to the right side from the point G, and the vehicle body position of the tractor is located on the right side of the reference line L (the lower side of the drawing in FIG. 16). The cutting angle of the front wheel 2 is less than the predetermined cutting angle e, and the direction of the vehicle body 1 is substantially parallel to the heel. Thereby, it is determined that the operation of the steering handle 6 is not accompanied by the avoidance of the obstacle S, and the turning mode is switched to the sensitive mode.

  At the H point, the moving distance Wx in the x direction from the B point is equal to or greater than a predetermined distance (6 m). When the H point is reached, the reference position a and the reference line L are reset, and the moving distance from the reference position a. When Wx and Wy are reset to the initial values (0 m) and the turning angle of the front wheel 2 is equal to or greater than the predetermined turning angle e, the reference position a and the reference line L are set, and the moving distance Wx, Calculation of Wy is started.

  Although not shown, when the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 are actuated in (C ′) and (F ′) of FIG. 16, the reference position a and the reference line L are reset. The moving distances Wx and Wy from the reference position a are reset to the initial value (0 m).

  Thereby, the obstacle S can be avoided and the tilling work can be continuously performed along the edge like the point I.

  As shown in FIG. 18 (a), in the tractor plowing operation, the rotary work device R is placed on the obstacle S so that the front side of the obstacle S (the left side of the obstacle S in FIG. 18) can be plowed as much as possible. In many cases, it is close to the front of the door. In this case, when the front part of the vehicle body 1 is brought close to the obstacle S, the obstacle S is located in front, and the width of the front part of the vehicle body is narrower than the width of the rotary working device R. 6 is operated relatively slowly to the left to avoid contact with the obstacle S.

  However, as shown in FIG. 18B, when the rotary working device R is located immediately behind the obstacle S, the width of the rotary working device R is wider than the width of the front portion of the vehicle body. In order to avoid contact of the rotary working device R with the steering handle 6, the steering handle 6 may be suddenly operated to the right. In this case, the obstacle S is often avoided by swinging the rotary working device R to the left side, and the soil plowed by the rotary working device R becomes difficult to be blown backward, and the obstacle S is in front of the obstacle S. Tillage marks (cultivation holes) are often formed.

  Therefore, contact with the obstacle S can be avoided, but since the cutting angle of the front wheel 2 is operated, the automatic lifting means 53 is activated, the rotary working device R is lifted, and the tilling work is interrupted. In addition, since the front wheel 2 is operated with a large turning angle, the front wheel speed increasing means 51 and the rear wheel braking means 52 are operated to cause the vehicle body 1 to turn sharply and avoid the obstacle S. There is a problem that it becomes difficult to correct the work travel route.

  In this tractor, since the control by the control device 50 is performed, the occurrence of the above-described problems can be prevented, continuous tilling work becomes possible, and workability of the tilling work can be improved.

[Other work status by turning judgment control]
Based on FIG. 19, the other work situation by turning determination control is demonstrated. FIG. 19 is a schematic plan view for explaining the working situation of the tractor.

  As shown in FIG. 19 (a), when plowing work is carried out while running along a cocoon in a deformed field where the cocoon is bent or the like, as shown in FIG. In the case of curved driving, since the vehicle is often driven at a relatively high speed and the steering handle 6 is operated relatively slowly, the threshold value of the steering speed of the steering handle 6 is changed to a high value by the threshold determination. Thus, even when the steering handle 6 is relatively operated, the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 are difficult to operate. Thereby, it is possible to prevent the automatic lifting means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 from operating even though the tilling work is being performed, and the tilling work can be continuously performed without interruption. it can.

  For example, when turning a headland (turning about 180 degrees on the shore), the vehicle is often driven at a relatively low speed, and the steering handle is often operated relatively quickly. As a result, the steering speed threshold value of the steering handle 6 is changed to be low, and the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 are easily operated. Thereby, the rotary working device R can be quickly raised and the vehicle body 1 can be turned in a small turn.

  As shown in FIG. 19C, when the alignment work is performed immediately after starting, or when the alignment operation is performed immediately after turning as shown in FIG. Therefore, the turning mode is switched to the insensitive mode, and the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 become difficult to operate. Thereby, it is possible to prevent the automatic ascending means 53, the front wheel speed increasing means 51, and the rear wheel braking means 52 from operating even though the tilling work is being performed, and in the state where the front wheel 2 is not driven at a speed increase, The vehicle can be aligned and traveled with high precision, and the rotary work device R once lowered can be prevented from rising during the alignment travel, so that the rotary work device R does not need to be lowered again.

[First Alternative Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention], the steering with respect to the vehicle speed V is controlled so that the threshold value of the steering speed of the steering handle 6 increases linearly in proportion to the increase in the vehicle speed V. Although the example in which the threshold value of the steering speed of the steering wheel 6 is set is shown, the threshold value of the steering speed of the steering handle 6 with respect to the vehicle speed V may be set as shown in FIG. FIG. 20 is a graph showing the relationship between the vehicle speed V and the steering speed threshold value of the steering handle 6 in this alternative embodiment. The horizontal axis in FIG. 20 is the vehicle speed V (km / hour), and the vertical axis in FIG. 20 is the steering speed (degrees / second) of the steering handle 6.

  As shown in FIG. 20A, the threshold of the steering speed of the steering handle 6 when the vehicle speed V is low is set low, and the threshold of the steering speed of the steering handle 6 when the vehicle speed V is high. May be set high, and the threshold line K may be set so that the steering speed of the steering handle 6 is changed in two stages with respect to the vehicle speed V.

  As shown in FIG. 20 (b), even if the threshold line K is set so that the threshold of the steering speed of the steering handle 6 increases stepwise as the vehicle speed V increases. Good. In this case, although not shown in the figure, when the vehicle speed V increases, the steering speed threshold value of the steering handle 6 may be changed in three stages. You may comprise so that a threshold value may be changed.

  As shown in FIG. 20 (c), the curve is adjusted so that the threshold value of the steering speed of the steering handle 6 is changed so that the rate of change of the steering speed of the steering handle 6 with respect to the increase in the vehicle speed V is gradually reduced. A curved threshold line K may be set.

  As shown in FIG. 20 (d), the curve is adjusted so that the threshold value of the steering speed of the steering handle 6 is changed so that the rate of change of the steering speed of the steering handle 6 with respect to the increase in the vehicle speed V gradually increases. A curved threshold line K may be set.

  As shown in FIG. 20 (e), a portion where the steering speed threshold of the steering handle 6 continuously increases linearly in proportion to the increase in the vehicle speed V, and the steering of the steering handle 6 with respect to the increase in the vehicle speed V. You may set the threshold line K provided with the part from which the rate of change of speed changes gradually.

  As shown in FIG. 20 (f), a portion where the threshold of the steering speed of the steering handle 6 continuously increases linearly in proportion to the increase in the vehicle speed V, and a stepped shape with respect to the increase in the vehicle speed V. A threshold line K including a portion where the steering speed threshold of the steering handle 6 increases stepwise may be set.

  As shown in FIG. 20, a lower limit portion where the threshold value of the steering speed of the steering handle 6 is constant may be provided in the low speed region of the threshold line K.

[ Second Embodiment of the Invention]
BEST MODE FOR CARRYING OUT THE INVENTION foregoing, and Oite in the first alternative embodiment of the invention] is detected by the steering angle sensor 65 the steering angle of the front wheel 2, the steering speed of the steering wheel 6 However, the turning angle sensor 65 may detect the turning angle of the front wheel 2 and the steering speed of the steering handle 6. Specifically, for example, the control device 50 may be configured to calculate the steering speed of the steering handle 6 by differentiating the turning angle of the front wheel 2 detected by the turning angle sensor 65 with respect to time.

  Further, the steering angle sensor 60 may be configured to detect the turning angle of the front wheel 2 and the steering speed of the steering handle 6. Specifically, for example, based on the steering angle of the steering handle 6 detected by the steering angle sensor 60 and the correlation data between the steering angle of the steering handle 6 and the turning angle of the front wheel 2, the front wheel is controlled by the control device 50. You may comprise so that 2 cut angles may be calculated.

[Third Another Embodiment of the Invention]
BEST MODE FOR CARRYING OUT THE INVENTION foregoing, [first alternative embodiment of the invention, and Oite to the second alternative embodiment of the invention] is rotary working apparatus as a working device to the tractor R However, as a working device, for example, a different working device such as a plow, a medicine spraying device, a hello, or a shaving may be attached to the tractor.

[ Fourth Embodiment of the Invention]
BEST MODE FOR CARRYING OUT THE INVENTION foregoing, [first alternative embodiment of the invention, Oite to the second alternative embodiment of the invention, and [the third alternative embodiment of the invention] Is an example of a tractor equipped with a front wheel 2 and a rear wheel 3 as a traveling device, but it can be similarly applied to a tractor equipped with a different traveling device, for example, a crawler traveling device (not shown) instead of the rear wheel 3. The same applies to tractors equipped with).

BEST MODE FOR CARRYING OUT THE INVENTION foregoing, [first alternative embodiment of the invention, Oite to the second alternative embodiment of the invention, and [the third alternative embodiment of the invention] Although a tractor is shown as an example of a work vehicle, it can be similarly applied to different work vehicles. For example, it can be similarly applied to a riding type rice transplanter, a multipurpose paddy field work vehicle, and the like.

Overall left side view of the tractor Schematic showing the structure of the steering device Plan view near the driving section Schematic plan view showing transmission structure of tractor Schematic showing the operating structure of the transmission switching device and side brake Block diagram of tractor control device Schematic plan view illustrating the calculation method of tractor travel distance and travel distance Flow chart of turning mode switching control Flow chart of turning determination control Flow chart of traveling content determination in turning determination control Flow chart of obstacle avoidance determination in turning determination control Graph of threshold judgment in turning judgment control Schematic explaining the predetermined elevation angle and the predetermined acceleration angle Flow chart when entering sensitive mode Flow chart for transition to insensitive mode Schematic plan view explaining the obstacle avoidance situation Table showing the status of each parameter at the tractor movement point Schematic plan view explaining the work situation when avoiding obstacles Schematic plan view explaining the work status of the tractor Graph showing the relationship between the steering speed threshold speed in the first alternative embodiment of the invention

1 Car body 2 Front wheel 3 Rear wheel
41 Side brake 50 Control device 51 Front wheel speed increasing means
52 Rear wheel braking means 53 Automatic raising means 60 Steering angle sensor (steering speed detecting means)
63 Vehicle speed sensor (vehicle speed detection means)
65 Cutting angle sensor (cutting angle detection means)
α1 First predetermined rising angle (predetermined rising angle)
α2 Second predetermined rising angle (predetermined rising angle)
β1 first predetermined acceleration angle (predetermined acceleration angle)
β2 Second predetermined acceleration angle (predetermined acceleration angle)
K threshold line (threshold)
R Rotary working device (working device)

Claims (7)

The vehicle body is equipped with a working device so that it can be raised and lowered, and includes a turning angle detecting means for detecting a turning angle of a front wheel, a vehicle speed detecting means for detecting a vehicle speed, and a steering speed detecting means for detecting a steering speed of a steering handle,
When the steering speed of the steering wheel detected by the steering speed detection means is greater than or equal to a threshold value and the turning angle of the front wheels detected by the turning angle detection means is greater than or equal to a predetermined rising angle, the state of the vehicle body is Automatic raising means for switching from a working state in which the working device is lowered to the lowered position to a non-working state in which the working device is raised to the raised position ;
A control device for a work vehicle in which the threshold value is set higher as the vehicle speed detected by the vehicle speed detection means becomes faster.   2. The work vehicle control device according to claim 1, wherein the threshold value is set so as to increase continuously as the vehicle speed detected by the vehicle speed detection means increases. When the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than the threshold value, and when the front wheel turning angle detected by the turning angle detecting means is greater than or equal to a predetermined acceleration angle, the front wheels and the rear wheels the driving state, comprising a substantially front-wheel acceleration means for switching the speed increasing drive state to drive faster speed higher than the peripheral speed of the same peripheral speed rear wheel front wheel from the constant velocity drive state to drive at a constant rate over the rear wheel of the front wheel The work vehicle control device according to claim 1 or 2 . If the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than the threshold value, and the turning angle of the front wheel detected by the turning angle detecting means is greater than or equal to the predetermined acceleration angle, 4. The work vehicle control device according to claim 3, further comprising rear wheel braking means for operating a rear wheel side brake to a braking side. A turning angle detecting means for detecting the turning angle of the front wheel, a vehicle speed detecting means for detecting the vehicle speed, and a steering speed detecting means for detecting the steering speed of the steering wheel;
When the steering speed of the steering wheel detected by the steering speed detecting means is greater than or equal to a threshold value and the turning angle of the front wheels detected by the turning angle detecting means is greater than or equal to a predetermined acceleration angle, the front and rear wheels Front wheel speed increasing means for switching the driving state from a constant speed driving state in which the front wheels are driven at a constant speed at substantially the same peripheral speed as the rear wheels to a speed increasing driving state in which the front wheels are driven at a speed higher than the peripheral speed of the rear wheels. ,
A control device for a work vehicle in which the threshold value is set higher as the vehicle speed detected by the vehicle speed detection means becomes faster. If the steering speed of the steering wheel detected by the steering speed detecting means is equal to or greater than the threshold value, and the turning angle of the front wheel detected by the turning angle detecting means is greater than or equal to the predetermined acceleration angle, 6. The work vehicle control device according to claim 5, further comprising rear wheel braking means for operating a side brake of the rear wheel to the braking side. The threshold value is provided with an upper limit portion in which the threshold value becomes constant in a high speed range where the vehicle speed detected by the vehicle speed detecting means is high. The work vehicle control device according to any one of claims 1 to 6, wherein the control device is configured not to change a threshold value.

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