Work vehicle

Abstract

To provide a work vehicle which can easily till the land at a ridge edge.SOLUTION: A work vehicle 1 comprises: a PTO normal / reverse clutch 16k which is configured so as to be able to switch rotation power of a PTO shaft driving a tiller W between normal rotation and reverse rotation; a ground-leveling body w4 which performs ground leveling behind a tilling body w3; and midair posture keeping means w47 which can keep the ground-leveling body w4 at a midair posture when the tilling body w3 is lowered to a work position. The work vehicle 1 is constituted so that backward traveling tilling where the backward traveling is performed while rotating the tilling body w3 in a reverse direction, can be executed through switching the rotation power of the PTO shaft 16 into reverse rotation by the PTO normal / reverse clutch in a condition that the tiller W is dropped to the work position. The ground-leveling body w4 is kept at the midair posture by the midair posture keeping means w47 during executing the backward traveling tilling.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a work vehicle for performing agricultural work, and in particular to a work vehicle equipped with a tiller. [Background technology]

[0002] Conventionally, as shown in Patent Document 1 below, for example, there is known a work vehicle that uses position information obtained from a satellite positioning system to perform agricultural work (hereinafter simply referred to as work) while driving automatically in a field. This type of automatically driven work vehicle can switch between manual and automatic driving, and when in automatic driving, it travels alternately between going straight and turning in order to travel efficiently throughout the entire field.

[0003] Furthermore, work vehicles are equipped with a detachable working implement attached to the rear of the traveling body. A known working implement is a tiller for tilling a field, as described in Patent Document 2 below. This conventional tiller is movable up and down relative to the traveling body using a lifting device. It includes tiller tines for tilling the soil in the field, a rotary cover that covers the top of the tiller tines, and a rear cover that is supported at the rear of the rotary cover so that it can move up and down. A tilling depth sensor is provided on the rotary cover to detect the tilling depth of the working implement. The tilling depth sensor is a potentiometer-type sensor that can detect the rotation angle of the rear cover relative to the rotary cover as the tilling depth. This allows the operator to raise and lower the tiller and adjust the tilling depth by performing a predetermined operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-069291 [Patent Document 2] Japanese Patent Application Publication No. 2023-048719 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, when a work vehicle turns near a ridge during work, it raises the tiller to a non-working position and turns so as not to come into contact with the ridge. Once the turn is complete, the tiller is lowered to a preset working position and tilling resumes. However, in the area where the vehicle turns back at the edge of the field, known as the headland, tilling cannot be performed because the tiller is raised to the non-working position during the turn.

[0006] Therefore, if the worker wants to start tilling from the edge of the field after turning, after completing the turn, he or she must first reverse the machine, move the tiller to the edge of the field, and then lower the tiller to the working position to resume tilling, which is time-consuming and reduces work efficiency.

[0007] In addition, when the tiller is raised to a non-working position to move it closer to the edge of the field and the work vehicle is then reversed, the raised tiller obstructs the view from the driver's seat, making it difficult and inconvenient to adjust the position of the tiller at the edge of the field, as this reduces visibility of the field scene.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a work vehicle that can solve these problems and easily plow right up to the edge of the ridges. [Means for solving the problem]

[0009] In order to achieve the above object, the first invention is: A work vehicle comprising a traveling vehicle body that travels in a field, a tiller disposed at the rear of the traveling vehicle body, and a lifting device that raises and lowers the tiller, A PTO forward / reverse clutch configured to switch the rotational power of the PTO shaft that drives the tiller between forward and reverse rotation, The tiller comprises a main body that is detachably connected to the rear of the work vehicle, a tilling body that is rotatably attached to the main body and rotates in a predetermined direction to perform tilling work, and a leveling body that is rotatably attached to the main body in the vertical direction around a left-right axis and performs leveling work behind the tilling body. A hollow posture maintaining means is provided that can maintain the ground leveling body in a hollow posture even when the cultivator is lowered to the working position, The work vehicle is configured to be able to perform reverse tilling, in which the rotational power of the PTO shaft is switched to reverse by the PTO forward / reverse clutch while the tiller is lowered to the working position, and the tiller body is rotated in reverse while the vehicle moves backward, and the hollow posture maintaining means maintains the ground leveling body in a hollow posture while the reverse tilling is being performed.

[0010] According to the first aspect of the present invention, the field can be tilled by moving the machine backwards using reverse tilling, making it easy to reach the edge of the field. Furthermore, since the tiller is lowered to its working position, it is less likely to obstruct the worker's view, making it easier to adjust the position of the tiller W at the edge of the field. Additionally, by maintaining the soil leveling body in a hollow position, it is possible to avoid loads (resistance) from the field surface and prevent damage.

[0011] The second invention is the first invention, a PTO speed change unit that changes the speed of the rotational power of the PTO shaft, When performing the reverse tilling, the PTO transmission unit is automatically switched to a preset speed ratio, and the lifting device is automatically controlled so that the height of the tiller becomes a preset height.

[0012] According to the second invention, in addition to the effects of the first invention, The tilling tines rotate at high speed, preventing them from being damaged or broken due to the load, while the load on the tilling tines due to reverse rotation is well suppressed, making tilling possible.

[0013] The third invention is the first or second invention, A tilling depth sensor is provided to detect the tilling depth by detecting the rotation angle of the soil leveling body, When the reverse sensor detects a change in the rotation angle of the soil leveling body during reverse tilling, the PTO forward / reverse clutch cuts off the rotational power of the PTO shaft, stopping the drive of the tiller and further stopping the movement of the machine body.

[0014] According to the third invention, in addition to the effects of the first or second invention, When the leveling body comes into contact with an obstacle during backward tilling, the rotation angle of the leveling body changes. By detecting the change in the rotation angle of the leveling body, the machine can be stopped and the tiller can be stopped, greatly improving safety.

[0015] The fourth invention is the third invention, During the backward tilling, when the vehicle speed exceeds a predetermined speed limit, the machine is controlled so that the vehicle speed is automatically kept below the predetermined speed limit; and The device is characterized in that it is configured to automatically control the aircraft so that the rotation speed of the PTO shaft is equal to or less than the predetermined limit rotation speed when the rotation speed of the PTO shaft at a predetermined time interval exceeds a predetermined limit rotation speed.

[0016] According to the fourth aspect of the present invention, in addition to the effects of the third aspect of the present invention, Furthermore, the load on the tiller tines can be reduced and safety can be improved. [Effects of the Invention]

[0017] According to the present invention, a work vehicle can be provided that can easily plow right up to the edge of the ridges. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a left side view of a work vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a left side view of the work machine of FIG. [Figure 3] FIG. 3 is an enlarged view of a main part of part B in FIG. [Figure 4]2 is a plan view showing the schematic configuration of a drive transmission system and a control system of the work vehicle of FIG. 1. FIG. [Figure 5] FIG. 5 is an explanatory diagram of the operating devices located in front of the cockpit. [Figure 6] FIG. 6 is an enlarged view of part A in FIG. [Figure 7] FIG. 7 is a schematic perspective view of the right side of the cockpit in FIG. [Figure 8] FIG. 8 is a block diagram showing the configuration of a control system including a control device for a work vehicle. [Figure 9] FIG. 9 is a flowchart showing an example of the backward tilling process. DETAILED DESCRIPTION OF THE INVENTION

[0019] A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. In the following description, unless otherwise specified, the forward direction of the work vehicle 1 (the direction from the operator's seat 8 to the steering wheel 9, which will be described later) will be referred to as the front, the opposite direction will be referred to as the rear, and the right side when facing forward will be referred to as the right, and the left side will be referred to as the left. The work vehicle 1 as a whole will sometimes be referred to simply as the vehicle body.

[0020] <1. Basic configuration of work vehicle> First, the basic configuration of a work vehicle 1 according to the embodiment will be described with reference to Figure 1. Figure 1 is a left side view of the work vehicle 1 according to the embodiment. In the following, a tractor will be used as an example of the work vehicle 1. Therefore, in the following, the work vehicle 1 will mainly be referred to as the tractor 1.

[0021] The tractor 1, which is a work vehicle, is an agricultural tractor that travels autonomously to perform work in fields, etc. The tractor 1 is operated by an operator (also called an operator) and travels within the field to perform predetermined tasks, and also performs predetermined tasks while automatically driving within the field through control of each part by a control system centered on a control device C (see Figure 3), which will be described later, that is disposed at an appropriate position on the vehicle body.

[0022] As shown in Fig. 1, the tractor 1 includes a traveling body 2 and a work implement W. The traveling body 2 includes a body frame 3, front wheels 4, rear wheels 5, a bonnet 6, an engine E, and a control unit 7. and a transmission case 10. The vehicle body frame 3 and the transmission case 10 form the main frame of the traveling vehicle body 2.

[0023] The front wheels 4 are a pair of left and right wheels, and are primarily used for steering (steered wheels). The rear wheels 5 are a pair of left and right wheels, and are primarily used for driving (drive wheels). The tractor 1 may be configured to be switchable between two-wheel drive (2WD) in which the rear wheels 5 are driven, and four-wheel drive (4WD) in which both the front wheels 4 and the rear wheels 5 are driven. In this case, both the front wheels 4 and the rear wheels 5 are drive wheels. The traveling body 2 may be equipped with a crawler device instead of wheels (front wheels 4 and rear wheels 5). In this case, the traveling crawler is the drive wheel.

[0024] The hood 6 is provided at the front of the traveling vehicle body 2 so as to be able to be opened and closed freely. The hood 6 can be rotated (opened and closed) in the vertical direction with the rear part as the rotation center. When closed, the hood 6 covers the engine E mounted on the vehicle body frame 3. The engine E is the driving source of the tractor 1 and is a heat engine such as a diesel engine or a gasoline engine.

[0025] The control unit 7 receives operations from the worker and functions to steer the work vehicle 1, and a control room is defined by a cabin box 7a that covers the top of the traveling body 2, and the control room is configured to be equipped with various operating members that receive operations from the worker, such as a driver's seat 8 where the worker sits and a steering wheel 9. The steering wheel 9 is a member that steers the front wheels 4, which are the steered wheels, and is steered manually by the worker during manual operation, and automatically steers by a steering device 31 that is configured including a steering actuator, steering cylinder 31s, etc. (not shown) during automatic operation.

[0026] The transmission case 10 houses a transmission (a speed change device 32). The power (rotational power) output from the engine E is appropriately reduced (shifted) by the transmission and transmitted to the front wheels 4 and rear wheels 5 via the front axle 4j and rear axle 5j, as well as to the PTO shaft 16. The transmission case 10 also houses a PTO forward / reverse clutch 16k, a PTO speed change unit 16h, etc., which make it possible to control the transmission (on / off, speed change) of power to the PTO shaft (see FIG. 8). This enables the work vehicle A to control the drive of the work implement W.

[0027] A work implement W that performs work in the field is connected to the rear of the traveling body 2, and a PTO shaft 16 that transmits power to drive the work implement W protrudes rearward from the transmission case 10. The PTO shaft 16 transmits rotational power that has been appropriately reduced by the transmission to the work implement W that is attached to at least the rear of the traveling body 2.

[0028] In addition, a lifting device 12 that raises and lowers the work implement W is provided at the rear of the traveling body 2. The lifting device 12 raises the work implement W to move it to a non-working position. The non-working position is a position where the work implement W is raised when, for example, the traveling body 2 moves backward or turns. In addition, the lifting device 12 lowers the work implement W to move it to a ground work position. The lifting device 12 includes a hydraulic lifting cylinder 121, a lift arm 122, a lift rod 123, a lower link 124, and a top link 125.

[0029] When hydraulic oil is supplied to the lift cylinder 121, the lift arm 122 rotates around the axis AX, which serves as the rotation fulcrum, to raise the work implement W, and when hydraulic oil is discharged from the lift cylinder 121, the lift arm 122 rotates around the axis AX to lower the work implement W. A lift arm sensor 26 that detects the rotation angle of the lift arm 122 is provided at the base of the lift arm 122 (near the axis AX). The height of the work implement W is calculated based on the detection result of the lift arm sensor 26. In this way, by extending and retracting the lift cylinder 121, the position of the work implement W can be switched between a working position where the work implement W is lowered to perform work (in other words, a height position where the tillage body w3, described later, touches the ground), and a non-working position where the work implement W is raised to perform no work (in other words, a height position where the tillage body w3, described later, does not touch the ground).

[0030] The positioning device 30 is, for example, a GNSS (Global Navigation Satellite System) antenna, and can perform positioning and timing by receiving radio waves from navigation satellites S orbiting the sky. It can also calculate the traveling speed from the history of positioning results and the Doppler effect of radio waves. During autonomous driving, a control device C (described later) acquires positioning information (in other words, vehicle position information) from the positioning device 30 to calculate the vehicle's position, and controls the steering device 51 to eliminate deviation from a predetermined target driving route, thereby enabling autonomous driving. The positioning device 30 also includes an IMU (Inertial Measurement Unit), which can simultaneously measure the tilt angle of the traveling vehicle body 2 (i.e., the tilt of the field).

[0031] The lift arm 122 is connected to the lower link 124 via the lift rod 123. In this way, the lifting device 12 connects the work machine W to the traveling body 2 via the lower link 124 and the top link 125 so that the work machine W can be raised and lowered. The lower link 124 is attached to the rear of the transmission case 10.

[0032] The tractor 1 also allows the operator to set various tasks for a specific field by operating an information processing terminal (a mobile terminal such as a tablet terminal) 100. The information processing terminal 100 includes a storage unit configured with, for example, a hard disk, a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and a display unit and operation unit configured with a touch panel. Note that various keys, buttons, etc. may also be provided separately as the operation unit.

[0033] <2. Configuration of the work machine (cultivator)> FIG. 2 is a left side view of the work machine W of FIG. The work implement W is a machine that performs work (plowing) in a field. In this embodiment, the work implement W is a rotary tiller that performs tilling work in a field, and performs tilling and leveling work (agricultural work) while moving across the field in the direction of travel by the tractor 1. Therefore, hereinafter, the work implement W will mainly be referred to as the tiller W. For the basic configuration of a rotary tiller, see, for example, Japanese Patent Application Laid-Open No. 2013-208089.

[0034] The tiller W comprises a main body w2 that is detachably connected to a three-point link at the rear of the tractor 1, a tiller body (rotary) w3 that is rotatably mounted on the main body w2 and performs tilling work while rotating in a predetermined direction (for example, the down-cut direction), and a soil leveling body (also called a leveling plate or rotary rear cover) w4 that is rotatably mounted on the main body w2 in the vertical direction (direction of arrow F) around a left-right axis (rotational fulcrum) w5 and performs soil leveling work behind the tiller body w3.

[0035] As shown in Figure 1, the main body w2 has a three-point linkage (traveling vehicle linkage) w11 that is detachably connected to the three-point linkage at the rear of the tractor 1. The three-point linkage w11 has one top mast w12 and two lower arms w13 (one on the left and one on the right). A top pin w14 is attached to the tip of the top mast w12, and a lower pin w15 is attached to the tip of the lower arm w13.

[0036] The main body w2 also has a transmission case w17, which is a shaft holder that rotatably holds an input shaft w16 extending in the front-rear direction, and inner ends of frame pipes w18, which are frames extending in the left-right direction, are attached to both the left and right sides of the transmission case w17. The input shaft w16 is connected to a PTO shaft 16 of the tractor 1 via a joint (not shown).

[0037] A chain case w19, which serves as a box-shaped tillage unit support, is attached to the outer end of the left frame pipe w18. A bracket (not shown), which serves as a plate-shaped tillage unit support, is attached to the outer end of the right frame pipe w18. The tillage unit w3 is rotatably supported by the chain case w20 and bracket (not shown), which are spaced apart and facing each other. Side cover plates w10, which serve as side plates, are fixed to each of the chain case w19 and bracket w20.

[0038] Furthermore, the machine body w2 has a tilling cover part w21 that covers the upper part of the tilling body w3, and a ground leveling body w4 is attached to the rear end of this tilling cover part w21 so that it can rotate up and down around an axis w5. Between this ground leveling body w4 and the main body w2, a ground pressure adjustment means w22 is installed that can adjust the ground pressure of the ground leveling body w4.

[0039] The tillage unit w3 performs tilling work while rotating in a predetermined direction around a left-right rotation center axis X based on power from the input shaft w16. The tillage unit w3 has a tillage shaft w31, which is a rotating shaft extending left-right, and multiple tillage tines w32 that are detachably attached to the tillage shaft w31. A spline shaft portion (not shown) at the left end, which is one axial end of the tillage shaft w31, is rotatably attached to the chain case portion w19 via a boss portion (not shown), and a right shaft portion (not shown) at the right end, which is the other axial end of the tillage shaft w31, is rotatably attached to a bracket portion (not shown) via a boss portion (not shown).

[0040] The rotational power transmitted from the PTO shaft 16 to the input shaft w16 is transmitted via the transmission case w17 to the chain case w20, and then transmitted by a chain from the chain case w20 to the tillage shaft w31, rotating the tillage tines w32. As a result, the tillage tines w32 are configured to rotate forward or reverse in accordance with the forward or reverse rotation of the PTO shaft 16.

[0041] Next, the configuration around the ground pressure adjusting means w22 will be described in detail. The soil leveling body w4 is equipped with a soil leveling board w41 that receives and levels the soil tilled by the tillage tines w32, and rear brackets w42, which are a pair of left and right plate-like members erected on the top of the soil leveling board 41. The frame pipe section w18 is also equipped with front brackets w43, which are a pair of left and right plate-like members erected on the top of the frame pipe section w18.

[0042] Furthermore, one end (front end) of the ground pressure adjustment rod w44 is connected to the front bracket w43 so as to be rotatable about axis X2. The other end (rear end) of the ground pressure adjustment rod w44 is supported by the rear bracket w42 so as to be able to move back and forth in the direction of arrow F2. A biasing spring w45 that biases the rear end of the ground pressure adjustment rod w44 in a direction to rotate downward is provided above the rear bracket w42 and is wound around the ground pressure adjustment rod w44. The upper end of the biasing spring w45 abuts against a fixture w451 fixed to the ground pressure adjustment rod w44, and the lower end abuts against a ring body (not shown) provided on the rear bracket w42 so as to slidably pass through the ground pressure adjustment rod w44. As a result, when the ground leveling plate w41 rotates upward, the elastic force of the biasing spring w45 presses it downward (toward the field surface). A buffer spring w46 is provided below the rear bracket w42 of the ground pressure adjusting rod w44. In this way, the ground pressure adjusting means w22 is configured.

[0043] Next, the hollow attitude maintaining means w47 of the ground leveling body w4 will be described. Normally, when the tiller W is lowered to the working position, that is, when the tiller tines w32 are lowered to the position where the field is cultivated, the rear end of the soil leveling body w4 comes into contact with the ground. However, in this embodiment, even when the tiller tines w32 are lowered to the position where the field is cultivated (that is, the working position), a hollow attitude maintaining means w47 is provided that can maintain the soil leveling body w4 in a hollow attitude (an attitude where the rear end of the soil leveling body w4 does not come into contact with the ground).

[0044] The hollow attitude maintaining means w47 allows the overall length of the ground pressure adjusting rod w44 to be extended and retracted, and when the tiller W is in the working position, the overall length of the ground pressure adjusting rod w44 can be shortened to lift the rear end of the soil leveling body w4 and maintain it in an attitude where it is not in contact with the ground. More specifically, the hollow attitude maintaining means w47 is configured to extend and retract the ground pressure adjusting rod w44 using an electric actuator w48.

[0045] FIG. 3 is an enlarged view of a main part of part B in FIG. As shown in FIG. 3, the electric actuator w48 is configured to transmit the rotation of the motor shaft of the electric motor (DC motor) w481 to the gear head w482, and further transmit the rotation of the gear head w482 to the ball screw w483. The upper end rod w441 of the ground pressure adjustment rod w44 is threadedly engaged with the ball screw w483 and is configured to be movable in the direction of arrow F2 depending on the rotation direction of the ball screw w483. This allows the ground pressure adjustment rod w44 to extend or retract its entire length by driving the electric actuator w48. The lower end rod w442 of the ground pressure adjustment rod w44 is fixedly connected to the rear of the electric actuator w48 by a connector w484. The driving of the electric actuator w48 (electric motor w481) is controlled by a control device C, which will be described later. In this manner, the hollow posture maintaining means w47 is configured.

[0046] The tilling depth sensor w493, which detects the tilling depth of the tiller W, is mounted on the tilling cover portion w21. One end (front end) of a bent rod w492 is attached to a protruding piece w491 mounted on the top of the soil leveling unit w4. The other end of the bent rod w492 rotates the sensor arm of the tilling depth sensor w493 in response to the rotation of the soil leveling unit w4, detecting the rotation angle of the soil leveling unit w4 around axis X relative to the tilling cover portion w21. This allows the tilling depth, which indicates the tilling depth, to be detected. For details about the configuration of the tilling depth sensor w493, see, for example, Japanese Patent Application Laid-Open No. 2017-55668. Detection information from the tilling depth sensor w493 is transmitted to a control device C, which will be described later.

[0047] <3. Work vehicle sensors> Next, the group of sensors N arranged on the tractor 1 will be described. The obstacle sensor 20 functions to detect obstacles (people or objects) around the aircraft. This obstacle sensor 20 is a medium-range sensor, preferably an infrared sensor, that can detect obstacles by emitting an infrared beam and detecting the light reflected from the obstacle. In addition, the distance to the obstacle can be measured by measuring the time between emitting the infrared beam and detecting the light reflected from the obstacle. The obstacle sensor 20, which is an infrared sensor, detects obstacles two-dimensionally, with a detection range of, for example, several meters to several tens of meters. Note that other medium-range sensors, such as sonar or millimeter-wave radar, can also be used as the obstacle sensor 20, or a combination of these can be used.

[0048] The obstacle sensor 20 includes a front sensor 21 and a rear sensor 22. The front sensor 21 has a detection area that extends forward of the vehicle body, and the rear sensor 22 has a detection area that extends rearward of the vehicle body. The front sensor 21 is disposed at the front of the traveling vehicle body 2, for example, by being attached to a sensor mounting stay 13 provided in front of the hood 6, and detects obstacles (people or objects) that exist in front of the traveling vehicle body 2. The rear sensor 22 is disposed at the upper rear of the traveling vehicle body 2, for example, by being attached to the top of the cabin 7a, and detects obstacles that exist behind the traveling vehicle body 2. The angle of the rear sensor 22 relative to the cabin 7a, i.e., the traveling vehicle body 2, can be changed by a motor (not shown).

[0049] Although not described in detail, the tractor 1 also includes, as a sensor group N, in addition to the above-mentioned lift arm sensor 26, an engine rotation sensor 23 that detects the engine rotation speed, a vehicle speed sensor 24 that detects the vehicle speed, a steering angle sensor 25 that detects the steering angle of the front wheels 4, which are the steered wheels, and a lever sensor 35 that detects the operating positions of various operating levers, all of which are arranged in appropriate positions.

[0050] <4. Schematic configuration of drive transmission system and control system> FIG. 4 is a plan view showing a schematic configuration of the drive transmission system and control system of the work vehicle 1 of FIG. The rotational power output from the engine E is branched into power for the traveling system that drives the machine body and power for the working system that drives the tiller W.

[0051] Power of the propulsion system is transmitted from the engine E through the forward / reverse clutch 31k, the main transmission 32a, the auxiliary transmission 32b, and the rear wheel actuating device 5d to the rear wheels 5. Power is also transmitted from the auxiliary transmission 32b through the front wheel drive clutch 4k and the front wheel actuating device 4d to the front wheels.

[0052] The forward / reverse clutch 31k can connect or disconnect the transmission of power, and also has the function of switching the rotational power for forward or reverse transmission. The forward / reverse clutch 31k is configured such that the above-mentioned operation is controlled by a control device C, which will be described later, and the operator can switch between connecting and disconnecting the transmission of power by stepping on the clutch pedal 18, and can switch the rotational power for forward or reverse transmission by operating the forward / reverse lever 201.

[0053] The main transmission unit 32a has a plurality of gears and a shifter that changes the connections of the gears, and by appropriately changing the meshing of the plurality of gears with the shifter, it is possible to change the input rotation and output it, thereby changing the speed. The main transmission unit 32a is configured so that the speed ratio is controlled by a control device C, which will be described later, and so that the speed ratio can be changed when the operator operates the main transmission operating unit 17 (main transmission speed increase button 17a, main transmission speed decrease button 17b).

[0054] The sub-transmission unit 32b has the function of expanding the speed change range, and like the main transmission unit 32a, it has multiple gears and a shifter that changes the connections of those gears, and by appropriately changing the meshing of the multiple gears with the shifter, it is possible to change and output the rotation input from the main transmission unit 32a. The sub-transmission unit 32b is configured so that the speed ratio is controlled by a control device C, which will be described later, and the operator can change the speed ratio by operating the sub-transmission lever 14.

[0055] The rear wheel differential 5d rotatably supports the left and right rear axles to which the rear wheels 5 are attached, absorbs differential force, and transmits power from the sub-transmission unit 32b to the left and right rear axles to drive the rear wheels 5. Similarly, the front wheel differential 4d rotatably supports the left and right front axles to which the front wheels 4 are attached, absorbs differential force, and transmits power from the sub-transmission unit to the left and right front axles to drive the front wheels 4.

[0056] The front-wheel drive clutch 4k is a clutch that turns on and off the transmission of power to the front wheels 4. When the front-wheel drive clutch 4k is connected (connected), power from the auxiliary transmission unit 32b is transmitted to the front wheel differential 4d, resulting in four-wheel drive. On the other hand, when the front-wheel drive clutch 4k is disconnected (disconnected), power from the auxiliary transmission unit 32b is transmitted only to the rear wheels 4, resulting in two-wheel drive.

[0057] The power of the work system is transmitted from the engine E through a PTO forward / reverse clutch 16k and a PTO speed change section 16h to a PTO shaft 16, and drives a tiller W connected to the PTO shaft 16.

[0058] The PTO forward / reverse clutch 16k is a clutch that switches power transmission to the PTO shaft 16 on and off, and is equipped with a reverse gear and a reverse clutch gear (not shown), so that the rotational power can be switched between forward and reverse output. As a result, when the PTO forward / reverse clutch 16k outputs reverse, the PTO shaft 16 rotates in the reverse direction, causing the tiller tines w32 of the tiller W to rotate in the reverse direction. The operation of the PTO forward / reverse clutch 48 is controlled by a control device C (described later). The PTO shaft 16 is also provided with a PTO shaft rotation speed detection sensor 16s that detects the rotation speed of the PTO shaft 16, and detection information from the PTO shaft rotation speed detection sensor 16s is sent to the control device C (described later).

[0059] The PTO transmission unit 16h is configured to include a transmission clutch, multiple gears, etc., and can change (change the speed) of the power (in other words, the number of revolutions or rotation speed) input from the engine E via the PTO forward / reverse clutch 16k and transmit it to the PTO output shaft 16. The PTO transmission unit 16h is configured so that the transmission ratio is controlled by a control device C, which will be described later, and so that the transmission ratio can be changed when the operator operates a PTO transmission lever 354.

[0060] The left and right rear axles are provided with left and right brake devices 14b, 15b, respectively, that brake the rear wheels when activated. In this embodiment, the left brake pedal 14 and the right brake pedal 15 are provided independently, and the left and right brake devices 14b, 15b can be activated independently. Furthermore, left and right brake cylinders 14s, 15s are interposed between the left brake pedal 14, the right brake pedal 15, and the left and right brake devices 14b, 15b. The left and right brake devices 14b, 15b can be activated by extending and retracting the left and right brake cylinders 14s, 15s, respectively, without operating the left and right brake pedals. This allows a control device C, described later, to control the extension and retraction of the left and right brake cylinders 14s, 15s, thereby enabling automatic braking (autobrake). The control device C, described later, controls the extension and retraction of a steering sensor 31s, which is part of the steering device 31, based on detection information from the steering angle sensor 25, thereby changing the steering angle of the front wheels 4, 4 and enabling automatic steering of the work vehicle 1.

[0061] <5. Configuration of various control devices in the control section> Next, various operating devices provided around the steering wheel 9 will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is an explanatory diagram of the operating devices located in front of the cockpit 8. Fig. 6 is an enlarged view of part A in Fig. 5. Note that Fig. 6 shows part A in Fig. 5 as viewed from right to left. Furthermore, the types and arrangements of the operating devices shown in each figure are examples and are not limited to these.

[0062] As shown in Figure 5, as described above, the steering wheel 9 is provided in front of the driver's seat 8 (see Figure 1). In addition, a clutch pedal 18 is provided on the lower left side of the handle post 350 to which the steering wheel 9 is attached, and an accelerator pedal 19 and left and right brake pedals 14, 15 are provided on the lower right side of the handle post 350.

[0063] A forward / reverse lever 201 is provided on the upper left side of the handle post 350. An accelerator lever 351 for adjusting the rotation speed of the engine E and a blinker lever 352 are provided on the upper right side of the handle post 350. An engine key switch 353 for operating the drive (on / off) of the engine E is also provided on the right side of the handle post 350, and a PTO shift lever 354 is provided in the center.

[0064] A dashboard cover 355 is provided in front of the steering wheel 9. The dashboard cover 355 also has a meter panel 11 mounted thereon so as to be visible to the operator in the cockpit 8. The meter panel 11 also has a display unit (liquid crystal monitor) 356, an engine revolution meter (tachometer) 357, and the like. The liquid crystal monitor 356 displays various information such as a gear display that displays the current gear, a fuel consumption rate display, and a traveling speed display, and the fuel consumption rate display and the traveling speed display may be displayed so as to switch at regular intervals.

[0065] As shown in Figure 6, the right side of the dashboard cover 355 is provided with the travel mode selection switch 223, the engine mode selection switch 192, and the reverse tillage switch 358. When the engine mode selection switch 192 is pressed, the engine E is controlled with an engine output curve that provides low fuel consumption. The reverse tillage switch 358 is a switch that causes the machine to perform reverse tillage, which will be described later.

[0066] In this embodiment, the tractor 1 is configured to be switchable, by operating the driving mode selection switch 223, among a manual driving mode in which the tractor travels in a field by manual steering (the operator operates the steering wheel 9, etc.), an automatic driving mode in which the tractor travels in a field by automatic steering, and a road driving mode in which the tractor travels on roads. The manual driving mode and the automatic driving mode are control modes selected when working in a field, and have an upper limit on the vehicle speed. For example, the vehicle is controlled to travel only at low speeds (1 to 10 km / h). The road driving mode is a control mode selected, for example, when traveling on a road to a field, and, like the manual driving mode, the tractor travels by manual steering, but the upper limit on the vehicle speed is lifted and the vehicle is controlled to travel at high speeds (15 km / h or higher).

[0067] 7, the main transmission operation unit 17 (main transmission speed increase button 17a, main transmission speed decrease button 17b), the sub-transmission lever 14, the accelerator lever 151, the position lever 152, the lift position setting means (lift height dial) 90, the public road travel button 91, the operation panel storage section 62, etc. are provided on the right side of the operator's seat 8. Of these, the position lever 152 is operated when raising or lowering the lift arm 122.

[0068] Additionally, various operation switches such as a PTO automatic / manual changeover switch, a PTO on / off switch, an engine rotation indicator, an RPM increase adjustment switch, and an RPM decrease adjustment switch are provided on the right side of the cockpit 8. The operation panel storage section 62 stores an operation panel on which operation switches other than those described above are provided.

[0069] The lifting position setting means (lifting height dial) 90 is a dial-type operating member for adjusting the height of the tiller W. A control device C, which will be described later, controls the extension and contraction of the lifting cylinder 121, which is a hydraulic cylinder, based on the detected angle of the lift arm 122 detected by the lift arm sensor 26, thereby controlling the tiller W to be at the height set by the lifting position setting means 90 during operation. Information relating to the operation of the various operating levers, dials, and other switches described above is detected by the lever sensor 35 and detection sensors (not shown), and transmitted to the control device C, which will be described later.

[0070] <6. Configuration of the control system including the control device> FIG. 8 is a block diagram showing the configuration of a control system including a control device C of the work vehicle A. The control device C is an information processing device configured by combining multiple ECUs (Electronic Control Units). Each of the multiple ECUs is configured with a CPU that performs arithmetic processing and a memory that can read and write information required for the arithmetic processing. The CPU operates in accordance with various control programs stored in the memory, thereby realizing the configuration shown as functional blocks in Fig. 8.

[0071] 8, the control device C has an input side connected to the positioning device 30, the sensor group N, the engine key switch 36, the engine mode selection switch 192, and the driving mode selection switch 223 via an input / output signal processing unit (including a communication unit) not shown, thereby acquiring positioning information (aircraft position information) from the positioning device 30, detection and detection information from the sensor group N, and operation information from the engine mode selection switch 192 and the driving mode selection switch 223. The output side is connected to the engine E, the steering device 31, the transmission 32, the braking device 33, the lifting device 12, the PTO forward / reverse clutch 16k, the PTO transmission unit 16h, the electric actuator w48, etc., and can transmit control signals to these devices and mechanisms. It can also transmit various information to be displayed on the display unit 356.

[0072] The control device C is equipped with ECUs for controlling each mechanism of the vehicle, and more specifically, it is equipped with an operation system ECU 50 that controls the operation of each mechanism of the work vehicle 1, and a control system ECU 54 that determines the operation method (operation rules) of each mechanism. As shown in Fig. 8, the operation system ECU 50 is equipped with an engine ECU 51 that controls the operation of the engine E, a travel system ECU 52 that controls the operation of mechanisms related to travel such as the steering device 31, transmission 32, and braking device 33, and a work machine ECU 53 that controls the operation (lifting and lowering) of the lifting device 12.

[0073] As described above, the steering device 31 includes a steering actuator, a steering cylinder 31s, etc., and is a device that automatically steers the steering wheel 9 during automatic driving. The speed change device 32 is a transmission housed in the transmission case 10, and is a device that changes the speed of the rotational power output from the engine E. The braking device 33 includes left and right brake cylinders 14s, 15s, left and right brake devices 14b, 15b, etc., and is a device that brakes the aircraft.

[0074] The control device C includes a communication unit 60, which is a communication mechanism that connects with an external device physically separated from the control device C via a network NW and exchanges information through communication. In this embodiment, the communication unit 60 is connected to at least the mobile information terminal 100, and is capable of sending and receiving information.

[0075] <7. Example of control by control device (control system ECU)> The configuration of the control system ECU 54 will be described in more detail below, along with control examples. The control system ECU 54 is equipped with, as control programs, a driving control unit 56 that controls the driving of the machine body, and a reverse tilling processing unit 57 that executes processing for plowing while moving the machine body backward (hereinafter referred to as reverse tilling).

[0076] The control system ECU 54 also has a work information database DB in which work information, which is information related to work, is stored. The work information includes, for example, field information, which is information related to the field, a planned travel route related to travel, and the working width of the work implement W (cultivator W). The field information also includes field information necessary for the work, such as information on the shape, position, size, range, ridge position, latitude, longitude, and altitude of each field to be worked on.

[0077] [Control example] (I) Manual driving mode, automatic driving mode, road driving mode The driving control unit 56 includes a manual driving control unit 56a that controls driving in the manual driving mode, an automatic driving control unit 56b that controls driving in the automatic driving mode, and an on-road driving control unit 56c that controls driving in the on-road driving mode 56c. Here, controlling driving means, in more detail, acquiring necessary detection information from the sensor group N to execute each mode, and sending necessary control commands to the operating ECU 50 when each mode is selected.

[0078] Each operation mode is well known and will not be described in detail. However, in the automatic operation mode, a planned travel route corresponding to the work to be performed by the work implement W (tiller W) is determined in advance for each field, digitized, and stored in a work information database DB. Based on the measurement results of the positioning device 30, various components such as the engine E, steering device 51, transmission 52, braking device 33, and lifting device 12 are controlled so that the work implement W travels along the stored planned travel route. The planned travel route is usually designed to alternate between straight travel routes and turning routes to efficiently travel the entire field, and the spacing between the straight travel routes is determined by the working width of the work implement W (tiller W) so that the work areas do not overlap. Furthermore, the specific planned travel route is designed depending on the shape and size of the field, the width, length, and number of ridges formed in the field, etc. The planned driving route may be designed by the control device C after receiving information about the field and input from the operator, or the control device C may be configured to obtain information about the planned driving route designed by an external computer via the network NW.

[0079] In the manual driving mode, the operator can steer the machine by operating the steering wheel 9 to travel in a field. Similarly, in the road driving mode, the operator can steer the machine by operating the steering wheel 9 to travel on the road, but as described above, the upper limit of the vehicle speed is controlled so that the machine can travel at low speeds in the manual driving mode and at high speeds in the road driving mode.

[0080] (II) Backward tillage treatment The backward tilling processing unit 57 is a program that executes the backward tilling process. Figure 9 is a flowchart showing an example of the backward tilling process. The backward tilling process starts, for example, when work starts (the engine key switch 353 is turned on).

[0081] When the reverse tilling process starts, the reverse tilling processing unit 57 determines (monitors) whether the operator has performed a start operation to start reverse tilling (Step #1). Here, the start operation is, for example, when the reverse tilling switch 358 is pressed and the forward / reverse lever 201 is operated to the reverse side.

[0082] If it is determined that a start operation has been performed (Y in step #1), it is determined whether the start conditions for starting reverse tilling are met (step #2). Here, the start conditions may be, for example, that the vehicle speed is equal to or less than a first threshold (e.g., 8 km / h) and / or that the PTO gear is equal to or less than a certain speed (preferably, the operator can select and set in advance whether to use an AND condition or an OR condition). Since the tiller tines w32 are kicked downward assuming forward rotation (forward rotation), there is a risk of damage if they contact the ground during high-speed reverse rotation. Therefore, if the start conditions are not met, reverse tilling is not started, thereby preventing damage to the tiller tines w32. If it is determined that the start conditions are not met (N in step #2), the process returns to step #1. Another start condition may be that the operating position of the lifting position setting means (lifting height dial) 90 is not in the position that raises the tiller W (working implement W) to the "highest position." This is to prevent malfunction due to erroneous operation when the tiller W (working machine W) is in the non-working position.

[0083] If it is determined that the conditions satisfy the start condition (Y in step #2), the vehicle speed is automatically changed (the main transmission unit 32a and the sub-transmission unit 32b are automatically switched to the gear ratio preset for reverse tilling) (step #3). This prevents the machine from traveling at high speed during reverse tilling, which will be described later, and allows it to travel stably at a low speed.

[0084] Next, the reverse tilling processing unit 57 automatically shifts the PTO output (step #4). Specifically, the PTO shifting unit 16h is automatically switched to a gear ratio preset for reverse tilling. This prevents the tilling tines w32 from rotating at high speed during reverse tilling (described later) and being damaged or broken by the load.

[0085] Next, the reverse tilling processing unit 57 automatically adjusts the height of the tiller W (working machine W) (step #5). Specifically, the lifting cylinder 12 is automatically controlled so that the height of the tiller W is a height preset for reverse tilling. Here, the height of the tiller W preset for reverse tilling is a height that allows the tiller tines w32 to till the field, and is preferably set a predetermined distance above the standard height for tilling. This makes it possible to till the field while reducing the load on the tiller tines w32 due to reverse rotation.

[0086] Next, the backward tilling processing unit 57 controls the hollow attitude maintaining means w47 to raise the rear end of the soil leveling body w4, move it away from the field surface, and maintain it in a hollow attitude (step #6). Here, in the backward tilling described below, if the soil leveling body w4 is on the ground, a forward load (resistance) is applied to the soil leveling body w4 from the field surface as the machine moves backward, which may normally cause damage to the soil leveling body w4. Therefore, by raising the rear end of the soil leveling body w4 and maintaining it in a hollow attitude, the load (resistance) from the field surface can be avoided and damage can be prevented.

[0087] Next, the reverse tilling processing unit 57 starts reverse tilling (step #7). In detail, while automatically moving backward at a low speed (for example, 3 km / h, about the speed at which a person walks), the PTO shaft 16 is rotated in reverse by switching control of the PTO forward / reverse clutch 16k, and the tiller tines w32 of the tiller W are rotated in reverse. This allows the field to be tilled while moving the machine backward, making it easy to till the edge of the field. Also, at this time, because the tiller W is lowered to the working position, the tiller W is less likely to obstruct the operator's view, making it easy to adjust the position of the tiller W at the edge of the field.

[0088] After reverse tilling has started, while reverse tilling is being performed, the reverse tilling processing unit 57 determines whether an interruption condition, which is a condition for interrupting reverse tilling, is met (step #8). Here, the interruption condition is a condition under which it is determined that continuing reverse tilling is inappropriate. For example, the interruption condition can be a change in the tilling depth detected by the tilling depth sensor w493 (in other words, a change in the rotation angle of the soil leveling unit w4). That is, during reverse tilling, the soil leveling unit w4 is normally maintained in a hollow position and its rotation angle is constant. However, if the soil leveling unit w4 comes into contact with an obstacle, the rotation angle of the soil leveling unit w4 changes. As a result, if the soil leveling unit w4 comes into contact with an obstacle, the machine's travel is stopped in a later step, and the tiller W is stopped, thereby significantly improving safety. The interruption condition can also be that the steering wheel 9 has been turned a certain amount or more. This allows, for example, if an operator (driver) discovers an obstacle while reversing tillage and tries to avoid it, to immediately interrupt reversing tillage by operating the steering wheel 9, thereby improving safety. Also, if the operator tries to turn the machine, reversing tillage can be immediately interrupted, improving work efficiency. The interruption condition can also be that an obstacle has been detected by the obstacle sensor 20 within a predetermined distance from the machine.

[0089] If it is determined that the interruption condition is met (Y in step #8), the machine stops traveling (reverse) (step #9), and the PTO forward / reverse clutch 16k cuts off power transmission to the PTO shaft 16, stopping the drive of the tiller W (step #10). Furthermore, the lifting device 12 is controlled to raise the tiller W to a non-working position (step #11), and the process ends. This ensures safety when a reason for interrupting reverse tilling occurs, that is, when the interruption condition is met.

[0090] Furthermore, if the interruption condition is not met during reverse tilling after it has started (N in step #8), it is determined whether the termination condition, which is the condition for terminating reverse tilling, is met (step #12). Here, the termination condition is a condition for normally terminating reverse tilling, and can be, for example, that the forward / reverse lever 201 has been operated to the forward side. Alternatively, the termination condition can be that the left and right brake pedals 14, 15 have been depressed a predetermined amount or more.

[0091] If it is determined that the termination condition is met (Y in step #12), travel (reverse) is stopped (step #13), and the PTO shaft 16 is returned to forward rotation by switching control of the PTO forward / reverse clutch 16k (step #14). Furthermore, the lifting cylinder 12 is automatically controlled (step #15) to return the height of the tiller W to the height before the start of reverse tilling (the height set by the lifting position setting means 90), and the process ends.

[0092] The embodiments of the present invention have been described above. The present invention is not limited to the above-described embodiments. It goes without saying that modifications may be made as appropriate within the scope of the technical concept. Other embodiments will be described below.

[0093] The control device C of the work vehicle 1 may be configured to automatically stop the machine when the tiller W reaches the edge of the ridge during backward tilling. The determination that the tiller W has reached the edge of the ridge may be made, for example, by determining the position of the tiller W and the ridge based on the position information from the positioning device 30 and the position information of the ridge included in the field information. The distance between the tiller W and the ridge may be determined by calculating the shortest distance between the tiller W and the ridge. The distance between the tiller W and the ridge may also be determined by calculating the shortest distance between the tiller W and the ridge based on the detection information from the rear sensor 22. To prevent work from being resumed with the soil leveling body w4 maintained in a hollow position when the forward / reverse lever 201 is operated to the forward side after backward tilling, the control device C may control the hollow position maintaining means w47 of the soil leveling body w4 to automatically return the overall length of the ground pressure adjusting rod w44 to its normal length.

[0094] When performing reverse tilling, the reverse speed may be changed according to the amount of depression of the accelerator pedal 19. In this case, the control device C may be configured to acquire vehicle speed information from the vehicle speed sensor 24, and when the vehicle speed exceeds a predetermined speed limit (e.g., 3 km / h), automatically control the machine to keep the speed below the predetermined speed limit. This makes it possible to reduce the load on the tiller tines w32 while improving safety.

[0095] Furthermore, when performing reverse tilling, the PTO shift lever 354 may be operated to change the speed of the PTO shaft 16 by changing the speed using the PTO shift unit 16. In this case, the control device C may be configured to obtain information regarding the rotation speed of the PTO shaft 16 using the PTO shaft rotation speed detection sensor 16s, and to automatically control the machine (by using the PTO shift unit 16 to change the speed) to keep the rotation speed of the PTO shaft 16 below the predetermined limit speed when the rotation speed of the PTO shaft 16 over a predetermined time interval exceeds a predetermined limit speed. This makes it possible to reduce the load on the tiller tines w32 while improving safety. [Explanation of symbols]

[0096] 1 Tractor (work vehicle) 2 Running vehicle 3 Body frame 4 front wheels 5 rear wheels 6. Bonnet 7 Control Unit 7a Cabin 8. Cockpit 9. Steering wheel 12 Lifting device 20 Obstacle Sensor 21 Front sensor 22 Rear sensor 26 Lift arm sensor 30 Positioning device 36 Engine key switch 100 Mobile Information Terminals 100a small camera E-Engine S navigation satellite W Work equipment (tiller)

Claims

1. A work vehicle comprising a traveling vehicle body that travels in a field, a tiller disposed at the rear of the traveling vehicle body, and a lifting device that raises and lowers the tiller, A PTO forward / reverse clutch configured to switch the rotational power of the PTO shaft that drives the tiller between forward and reverse rotation, The tiller comprises a main body that is detachably connected to the rear of the work vehicle, a tilling body that is rotatably attached to the main body and rotates in a predetermined direction to perform tilling work, and a leveling body that is rotatably attached to the main body in the vertical direction around a left-right axis and performs leveling work behind the tilling body. A hollow posture maintaining means is provided that can maintain the ground leveling body in a hollow posture even when the cultivator is lowered to the working position, The work vehicle is configured to be able to perform reverse tilling, in which, with the tiller lowered to the working position, the rotational power of the PTO shaft is switched to reverse using the PTO forward / reverse clutch, causing the tiller body to rotate in reverse while moving backward, and the hollow attitude maintaining means maintains the leveling body in a hollow attitude while the reverse tilling is being performed.

2. a PTO speed change unit that changes the speed of the rotational power of the PTO shaft, The work vehicle according to claim 1, characterized in that, when performing the reverse tilling, the PTO transmission is automatically switched to a preset speed ratio, and the lifting device is automatically controlled so that the height of the tiller is set to a preset height.

3. A tilling depth sensor is provided to detect the tilling depth by detecting the rotation angle of the soil leveling body, A work vehicle as described in claim 1 or claim 2, characterized in that when the reverse sensor detects a change in the rotation angle of the soil leveling body while the reverse tilling is being performed, the PTO forward / reverse clutch cuts off the rotational power of the PTO shaft, stopping the drive of the tiller and further stopping the movement of the machine body.

4. During the backward tilling, when the vehicle speed exceeds a predetermined speed limit, the machine is controlled so that the vehicle speed is automatically kept below the predetermined speed limit; and 4. The work vehicle according to claim 3, characterized in that when the rotation speed of the PTO shaft at a predetermined time interval exceeds a predetermined limit rotation speed, the vehicle body is controlled so that the rotation speed of the PTO shaft is automatically kept below the predetermined limit rotation speed.

Images