Work vehicle

Abstract

To provide a work vehicle that improves safety of a worker.SOLUTION: A work vehicle includes: an engine which is provided in a travel vehicle body; a hydraulic continuously variable transmission which changes the power input from the engine and outputs it; a setting tool which has an operation tool that can adjust the vehicle speed of the travel vehicle body by adjusting the trunnion opening of the hydraulic continuously variable transmission, in which the engine speed is set by an operation amount of the operation tool, and which accepts a change operation for the upper limit opening of the trunnion opening of the hydraulic continuously variable transmission by the operation tool; and a control device which sets the upper limit opening of the trunnion opening in accordance with an operation state of the setting tool. The work vehicle is configured such that the engine speed increases when the operation tool is further operated in a state where the trunnion opening reaches its upper limit, and can increase the speed due to the rise in engine speed for vehicle speed adjustment beyond the upper limit of the trunnion opening.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, there is known a work vehicle that sets the vehicle speed of a traveling vehicle body according to the amount of depression of a shift pedal provided on the traveling vehicle body and causes the traveling vehicle body to travel (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when loading a work vehicle onto a truck, unloading a work vehicle from a truck, or moving the work vehicle in and out of a field on an inclined surface, it is required to finely adjust an operating tool such as a shift pedal.

[0005] However, in the above technology, due to the inclination or vibration of the traveling vehicle body, it may be difficult to finely adjust an operating tool such as a shift pedal when moving on an inclined surface. Therefore, when moving on an inclined surface, the traveling vehicle body may move unexpectedly for the operator, and there is room for improvement in the safety of the operator.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a work vehicle that improves the safety of an operator.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a work vehicle according to one aspect of the embodiment includes an engine provided on a traveling vehicle body, a hydraulic continuously variable transmission that changes and outputs the power input from the engine, and an operation tool capable of adjusting the vehicle speed of the traveling vehicle body by adjusting the trinion opening of the hydraulic continuously variable transmission. The rotational speed of the engine is set according to the operation amount of the operation tool, and includes a setting tool that receives a change operation of the upper limit opening of the trinion opening of the hydraulic continuously variable transmission by the operation tool, and a control device that sets the upper limit opening of the trinion opening according to the operation state of the setting tool. In a state where the upper limit of the trinion opening is reached, when the operation tool is further operated, the engine rotational speed increases, and for vehicle speed adjustment above the upper limit of the trinion opening, the speed can be increased by the increase in the engine rotational speed.

Effect of the Invention

[0008] According to one aspect of the embodiment, the work vehicle can improve the safety of the operator.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0010] First, with reference to FIGS. 1 and 2, an overview of the work vehicle 1 according to the embodiment will be described. FIG. 1 is a side view showing the work vehicle 1. FIG. 2 is a plan view showing the work vehicle 1.

[0011] In the following description, the front-rear direction is the traveling direction when the work vehicle 1 travels straight, and the front side in the traveling direction is defined as "front" and the rear side as "rear". The traveling direction of the work vehicle 1 is the direction from the driver's seat 41 to the steering wheel 35 (steering device) when traveling straight (see FIGS. 1 and 2).

[0012] The left-right direction is a direction horizontally orthogonal to the front-rear direction, and the left and right are defined toward the "front" side. That is, when the operator (also referred to as the worker) is seated in the driver's seat 41 and facing forward, the left hand side is "left" and the right hand side is "right".

[0013] The up-down direction is the vertical direction. The front-rear direction, the left-right direction, and the up-down direction are orthogonal to each other. Each direction is defined for convenience of explanation, and the present invention is not limited by these directions.

[0014] In the embodiment, the work vehicle 1 will be described as a riding type seedling transplanter 1 having a seedling planting part 4 as a work device and receiving seedlings in a field. As shown in FIGS. 1 and 2, the seedling transplanter 1 includes a vertically movable seedling planting part 4 for planting seedlings in a field via a lifting link mechanism 3 on the rear side of the traveling vehicle body 2.

[0015] The main body part of the fertilizer applicator 5 is arranged on the upper rear part of the traveling vehicle body 2. When the work vehicle 1 is not the seedling transplanter 1, it may be provided with a seeding device for supplying seeds or the like as a work device.

[0016] The traveling vehicle body 2 is a four-wheel drive vehicle equipped with left and right front wheels 10 and rear wheels 11, which are wheels and drive wheels. On the front side of the main frame 15 that constitutes the vehicle body skeleton of the traveling vehicle body 2, there are a transmission case 13 that transmits driving force to the seedling planting part 4 and the like, and a hydraulic continuously variable transmission device 14 that outputs the driving force supplied from the engine 30, that is, the rotation generated by the engine 30, to the transmission case 13.

[0017] The continuously variable transmission device 14 is a hydrostatic continuously variable transmission called a so-called HST (Hydro Static Transmission). Hereinafter, the case where the continuously variable transmission device is the HST 14 will be described.

[0018] Here, the HST 14 will be described with reference to FIG. 3. FIG. 3 is an explanatory diagram of the HST 14.

[0019] As shown in FIG. 3, the HST 14 drives the hydraulic pump 141 with the power from the engine 30 to generate hydraulic pressure, and converts this hydraulic pressure into mechanical force (rotational force) by the hydraulic motor 142 and outputs it. At this time, by operating the main shift operation lever 36 described later, the rotation angle of the trunnion shaft 147 of the HST 14 (hereinafter referred to as the "trunnion opening") is changed through a trunnion shaft actuator such as the HST motor 146, and thereby the inclination angle of the swash plate 148 is changed, so that the output of the HST 14 can be changed steplessly.

[0020] That is, pressure oil corresponding to the inclination angle of the swash plate 148 is supplied from the hydraulic closed circuit 143 to the hydraulic motor 142, and the output shaft 145 is driven by this hydraulic motor 142 to change the rotational speeds of the front wheels 10 and the rear wheels 11. In this way, the HST 14 converts the power generated by the engine 30 into the force for driving the traveling vehicle body 2, and by changing the output and the output direction, the forward and backward movement and the traveling speed (vehicle speed) of the traveling vehicle body 2 can be operated. In FIG. 3, the reference numeral 80 indicates the input shaft of the HST 14, which is connected to the output shaft 30a of the engine 30 via the main clutch 30b. The trunnion shaft actuator may be hydraulic.

[0021] Returning to FIGS. 1 and 2, a sub-shifting mechanism 16 for switching the traveling mode of the traveling vehicle body 2 during traveling on the road in the high-speed mode or during planting of seedlings in the low-speed mode is provided in the transmission case 13. That is, the sub-shifting mechanism 16 switches between the road speed in the high-speed mode and the planting speed in the low-speed mode. Front-wheel final cases 10a are provided on the left and right sides of the transmission case 13, and front wheels 10 are attached to left and right front axles 10b that project outward from front-wheel support portions capable of changing the steering direction of the left and right front-wheel final cases 10a.

[0022] In addition, rear-wheel gear cases 11a are attached to both the left and right sides of a rear frame 22 (see FIG. 2) provided laterally at the rear portion side of the main frame 15, and rear wheels 11 are respectively attached to left and right rear axles 11b that project outward from the rear-wheel gear cases 11a.

[0023] In addition, left and right link support frames 23 for supporting the lifting link mechanism 3 project upward at the upper portion of the rear frame 22. A pair of left and right lower link arms 24 are provided below the left and right link support frames 23 and between the left and right. A lifting cylinder 25 that operates by hydraulic pressure is provided between the left and right of the left and right lower link arms 24.

[0024] An upper link arm 26 is provided above the lifting cylinder 25, and the lifting link mechanism 3 which is a parallel link mechanism is configured. Note that the other end sides of the left and right lower link arms 24, the lifting cylinder 25, and the upper link arm 26, each of which has one end connected to the traveling vehicle body 2 side, are attached to the front portion of the seedling planting portion 4.

[0025] In addition, an engine 30 is mounted on the main frame 15. The rotational power of the engine 30 is transmitted to the transmission case 13 via a belt transmission device 21 and an HST 14. The rotational power transmitted to the transmission case 13 is shifted by the sub-shifting mechanism 16 in the transmission case 13 and then divided into traveling power and externally extracted power.

[0026] Also, the rotational power of the engine 30 is transmitted to the hydraulic pump. The hydraulic pressure generated by the hydraulic pump is supplied to the HST 14, the power steering mechanism 88 (see FIG. 3) of the handle 35, the lift cylinder 25, and the like.

[0027] The external extraction power taken out from the rotational power transmitted to the transmission case 13 is transmitted to the planting clutch case 27 provided at the rear part of the traveling vehicle body 2, and is transmitted from the planting clutch case 27 to the seedling planting part 4 by the planting transmission shaft 67.

[0028] On the other hand, left and right drive shafts 42 are provided at the rear part of the transmission case 13. The rotational power from the engine 30 is transmitted to the left and right rear wheel gear cases 11a via the transmission case 13 and the drive shafts 42.

[0029] Note that side clutches 44 (see FIG. 4) for engaging and disengaging the power transmission to the left and right drive shafts 42 are arranged on the upstream side in the transmission direction from the left and right drive shafts 42. As shown in FIG. 1, a side clutch pedal 43a for engaging and disengaging the left and right side clutches 44 is provided at the lower front side of the driver's seat 41 and on one side of the left and right.

[0030] When the side clutch pedal 43a on the inner side of turning is depressed to disengage the side clutch 44 and then the handle 35 is operated to perform turning travel, the driving rotation of the rear wheel 11 on the inner side of turning can be completely blocked.

[0031] A bonnet 39 with a control panel 38 for operating each part arranged at the upper part is provided at the upper front side of the traveling vehicle body 2. A monitor 86 (see FIG. 4) and the like are provided on the control panel 38.

[0032] Also, on the bonnet 39, a handle 35 for steering the traveling vehicle body 2, a main shift operation lever 36 for operating the HST 14 and the seedling planting part 4, a sub-shift operation lever 37 for operating the sub-shift mechanism 16, and the like are provided.

[0033] The main transmission operation lever 36 is an operating tool (first operating tool) capable of adjusting the vehicle speed of the traveling vehicle body 2 by adjusting the opening degree of the trunnion shaft 147 of the HST 14. The main transmission operation lever 36 is operated by, for example, the operator. The main transmission operation lever 36 receives a gear shifting operation by the operator.

[0034] The main transmission operation lever 36 is provided so as to be movable along the lever guide portion 815, for example, as shown in FIG. 4. FIG. 4 is a diagram for explaining the lever guide portion 815. As shown in FIG. 4, the lever guide portion 815 is roughly divided into a forward traveling region 811 on the front side of the machine body, a backward traveling region 813 on the rear side of the machine body, and a neutral region 812 positioned so as to be sandwiched therebetween. Note that the lever guide portion 815 in FIG. 4 is an example and is not limited thereto.

[0035] When the main transmission operation lever 36 is positioned in the forward traveling region 811, the seedling transplanter 1 moves forward and becomes faster as it approaches the foremost position. When the main transmission operation lever 36 is positioned in the backward traveling region 813, the seedling transplanter 1 moves backward and becomes faster as it approaches the rearmost position.

[0036] That is, the main transmission operation lever 36 is provided so as to be positionally changeable across the forward traveling region 811 and the backward traveling region 813 with the neutral region 812 interposed therebetween, and the output of the HST 14 can be adjusted according to the operation position. That is, according to the operation amount of the main transmission operation lever 36 within the lever guide portion 815, the inclination angle of the swash plate 148 of the HST 14 changes, and the output from the HST 14, that is, the traveling speed, is changed steplessly.

[0037] The rotational speed of the engine 30 is set by the operation amount of the main transmission operation lever 36. For example, when the main transmission operation lever 36 is positioned in the forward traveling region 811, the rotational speed of the engine 30 increases as the main transmission operation lever 36 approaches the foremost position.

[0038] When the other party positions the main transmission operation lever 36 in the neutral region 812, the output from the HST 14 is stopped and the seedling transplanter 1 stops. Further, in the seedling transplanter 1, at this time, brakes are forcibly applied to the front wheels 10 and the rear wheels 11.

[0039] The main transmission operation lever 36 is held at the position where the operator's operation has disappeared when the operator's operation disappears.

[0040] Also, as shown in FIG. 5, on the bonnet 39, a setting switch 49 (setting tool) that can change the upper limit opening of the trunion opening of the HST 14 and can be set is provided. FIG. 5 is a diagram for explaining the setting switch 49. The setting switch 49 is, for example, a switch provided so as to be rotatable in the vertical direction. The setting switch 49 is rotatable by the operation of the operator. The setting switch 49 receives a setting operation of the upper limit opening by the operator. The setting switch 49 is a switch for setting the upper limit opening of the trunion opening when the traveling vehicle body 2 is moving forward and when it is moving backward. The setting switch 49 may be a button type or the like.

[0041] When the setting switch 49 is, for example, in the upper first position, the vehicle speed mode is set to the first vehicle speed mode. In the first vehicle speed mode, the upper limit opening of the trunion opening is set to the first upper limit opening. The first upper limit opening is a normal upper limit opening and is set according to the position of the main transmission operation lever 36.

[0042] When the setting switch 49 is, for example, in the lower second position, the vehicle speed mode is set to the second vehicle speed mode. In the second vehicle speed mode, the upper limit opening of the trunion opening is set to the second upper limit opening. The second upper limit opening is smaller than the first upper limit opening. That is, the second vehicle speed mode is a mode in which the speed of the traveling vehicle body 2 is lower than that in the first vehicle speed mode.

[0043] The first upper limit opening degree and the second upper limit opening degree are set to different opening degrees when the traveling vehicle body 2 is moving forward and backward, respectively. For example, in the second vehicle speed mode, the second upper limit opening degree during backward movement is smaller than the second upper limit opening degree during forward movement.

[0044] For example, the vehicle speed in the second vehicle speed mode is about 20% of the vehicle speed in the first vehicle speed mode. Also, for example, the vehicle speed in the second vehicle speed mode during backward movement is about 30% of the vehicle speed in the first vehicle speed mode during backward movement.

[0045] Note that the trunion opening degree here is the opening degree with respect to the state where the swash plate 148 (see FIG. 3) is not tilted. The trunion opening degrees during forward movement and backward movement are, for example, the amounts of change with respect to the state where the swash plate 148 is not tilted, and both are described as positive values. Note that the setting switch 49 may be provided separately for forward movement and backward movement.

[0046] Returning to FIGS. 1 and 2, an openable and closable front cover 40 is provided on the front side of the bonnet 39. Inside the front cover 40, a fuel tank, a battery, and an interlocking mechanism for rotating the lower sides of the left and right front wheels 10 and the left and right front wheel final cases 10a in accordance with the steering of the steering wheel 35 are provided. The front wheels 10 are, for example, steering wheels that steer in response to the steering of the steering wheel 35.

[0047] An engine cover 30c that covers the upper and side portions of the engine 30 is provided on the rear side of the bonnet 39 and above the engine 30, and a driver's seat 41 on which the operator sits is provided on the upper portion of the engine cover 30c.

[0048] A fertilizer applicator 5 is provided on the rear side of the driver's seat 41 and on the rear end side of the main frame 15. The driving force of the fertilizer applicator 5 is transmitted by a fertilizer transmission mechanism provided so as to face the fertilizer applicator 5 from one side of the left and right rear wheel gear cases 11a.

[0049] On both the left and right sides at the lower part of the engine cover 30c and the bonnet 39, substantially horizontal floor steps 33 are formed. As shown in Fig. 2, the floor steps 33 are partially lattice-shaped. For example, even if mud stuck to, for example, the shoes of the operator walking on the floor steps 33 falls off, the fallen mud etc. will fall onto the field.

[0050] An accelerator pedal 110 (second operating tool) that can be stepped on by the operator is provided on the floor step 33. The accelerator pedal 110 is biased toward a predetermined initial position by a biasing means such as a spring, for example. Specifically, the accelerator pedal 110 is biased by the biasing means to the initial position when not stepped on by the operator. The accelerator pedal 110 rotates from the initial position according to the stepping force of the operator when stepped on by the operator. The accelerator pedal 110 returns to the initial position by the biasing force of the biasing means when the stepping by the operator stops.

[0051] Also, as shown in Fig. 2, a rear step 330 is connected to the rear of the floor step 33. It is preferable that the surface of the rear step 330 is subjected to an anti-slip process in which, for example, a plurality of protrusion patterns are formed so that the feet are less likely to slip during work.

[0052] Also, on the front side of the traveling vehicle body 2 and on both the left and right sides, a spare seedling frame 50 for arranging a plurality of spare seedling placing tables 52 at intervals in the vertical direction on the seedling frame support 51 is provided respectively, and work materials such as seedlings to be replenished to the seedling planting part 4 and fertilizer bags can be placed.

[0053] Also, at the rear end of the lifting link mechanism 3, a seedling tank 53 for loading seedlings to be planted in the field is mounted together with a sliding mechanism that slides in the left-right direction. In the seedling tank 53, long seedling partition fences 54 in the vertical direction are arranged at predetermined intervals in the left-right direction respectively. Below the seedling tank 53, a seedling planting device 55 for scraping up the loaded seedlings and planting them in the field is arranged.

[0054] The seedling planting device 55 is configured to plant the same number of rows as the number of planting operation rows partitioned by the seedling partition fence 54, that is, eight rows simultaneously. Four planting transmission cases 56 are arranged at intervals below the seedling tank 53, and planting rotaries 57 that pick up seedlings by the planting rods 58 while rotating are respectively mounted on both the left and right sides of the planting transmission case 56 and plant the seedlings in the field.

[0055] The fertilizer application device 5 has a fertilizer application hopper 70 in which fertilizer is stored, and is partitioned into the same number of rows as the number of working rows of the seedling planting section 4 (in the example shown in FIG. 2, eight rows). Since the fertilizer application hopper 70 for eight rows is long in the left-right direction, the convenience of fertilizer input and attachment / detachment is reduced. Therefore, a so-called side fertilizer application structure in which those partitioned into four rows each are arranged side by side on the left and right may be used.

[0056] Below the fertilizer application hopper 70, a feeding device 71 for supplying a set amount of fertilizer is provided for each row. Below the feeding device 71, a ventilation duct 72 through which the conveying air for moving the fertilizer passes is provided in the left-right direction. Below the feeding device 71, a fertilizer application hose 73 for guiding the fertilizer to the vicinity of the seedling planting position of the seedling planting section 4 is provided. Further, at one end of the ventilation duct 72, a blower 74 that is operated by a blower electric motor 76 to generate the conveying air is provided.

[0057] The amount of fertilizer supplied to the field (fertilizer application amount) can be adjusted by controlling the feeding device 71. For example, by controlling the rotation speed of the feeding section provided in the feeding device 71 and having a recess into which fertilizer flows from the fertilizer application hopper 70, the amount of fertilizer supplied to the field is adjusted.

[0058] As shown in FIGS. 1 and 2, below the seedling planting section 4, a center float 62C that contacts the field surface and slides, and two side floats 62L and 62R on the left and right are provided so as to be rotatable about an axis. In some cases, the center float 62C and the left and right side floats 62L and 62R are collectively referred to as the float 62.

[0059] Also, below the seedling planting part 4, in front of the float 62, a leveling rotor 63 for leveling the unevenness of the field surface is provided. For example, the driving force is transmitted to the leveling rotor 63 via a rotor transmission shaft 63a from the rear wheel gear case 11a on the left and right other sides.

[0060] Also, as shown in FIG. 1, on both the left and right sides of the seedling planting part 4, line markers 65 are respectively provided, with either the left or the right side in contact with the field surface to form a groove as a guide for traveling in the next working strip (next process). When either the left or the right line marker 65 touches the ground, the other side is separated upward. When the seedling planting part 4 is raised during turning, both the left and right sides are separated upward. When the seedling planting part 4 descends after turning, one side is separated upward and the other side touches the ground.

[0061] Also, as shown in FIGS. 1 and 2, at the left and right central part of the traveling vehicle body 2 and in front of the bonnet 39, a center mascot 66 that is long in the vertical direction is provided. By aligning the center mascot 66 with the groove formed in the field by the left and right line markers 65, it becomes possible to travel in accordance with the working position of the previous working strip, improving the working accuracy and preventing the occurrence of non-working.

[0062] Note that depending on the soil quality of the field, the guide lines formed by the left and right line markers 65 may be buried immediately, and the straight-ahead reference may disappear. In such a case, it is advisable to use the left and right side markers 19 provided in front of the left and right line markers 65. That is, by moving the left and right side markers 19 outward and positioning the side markers 19 above the planted seedlings, it becomes possible to perform the planting work in accordance with the planting of the seedlings in the previous working strip.

[0063] Also, as shown in FIG. 1, the seedling transplanter 1 is provided with a position detection device 150. The position detection device 150 detects the current position and orientation of the seedling transplanter 1. That is, the position detection device 150 detects information regarding the position and orientation of the traveling vehicle body 2. The position detection device 150 includes, for example, an orientation sensor and positioning means such as GPS (Global Positioning System) or GNSS (Global Navigation Satellite System). The position detection device 150 may be composed of a plurality of devices. The position detection device 150 may include a camera and an ultrasonic sensor, and may acquire the turning position in the field and detect the distance to the turning position.

[0064] For example, the position detection device 150 receives positioning information from the positioning means, creates current position information and orientation information of the traveling vehicle body 2 based on the received positioning information, and detects the current position and orientation. The position detection device 150 is attached to, for example, the attachment stay 59 and disposed above the traveling vehicle body 2.

[0065] The straight - travel control program and the turning control program created based on the position information by the position detection device 150 are stored in different locations. The straight - travel control program is stored, for example, in the straight - travel control ECU (Electronic Control Unit) 100a in the position detection device 150, and the turning control program is stored, for example, in the turning control ECU 100b housed in the bonnet 39. Note that the straight - travel control ECU 100a and the turning control ECU 100b are included in the control device 100 (see FIG. 3) described later. The straight - travel control ECU 100a and the turning control ECU 100b may be stored in the same ECU.

[0066] Next, the control system of the seedling transplanter 1 will be described with reference to FIG. 6. FIG. 6 is a block diagram showing the control system centered on the control device 100 of the seedling transplanter 1. The seedling transplanter 1 is capable of controlling each part by electronic control and is provided with a control device (hereinafter referred to as a controller) 100 for controlling each part.

[0067] The controller 100 is provided with a processing unit having a CPU (Central Processing Unit) etc., a storage unit such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and further an input / output unit, and these are connected to each other and can transfer signals to each other. A computer program for controlling the seedling transplanter 1 etc. is stored in the storage unit. The controller 100 exhibits each function by reading out a computer program etc. stored in the storage unit.

[0068] Connected to the controller 100 are, for example, as actuators, a throttle motor 80, hydraulic control valves 81, 82, a planting clutch operating solenoid 83, a side clutch operating solenoid 84, an HST motor 146, a wire drawing marker lifting motor 87, a steering motor 95, a differential lock switching motor 96, etc.

[0069] The throttle motor 80 increases or decreases the rotational speed of the output shaft 30a of the engine 30 by operating a throttle that adjusts the intake air amount of the engine 30. The hydraulic control valve 81 controls the telescopic operation of the lifting cylinder 25. The hydraulic control valve 82 controls the power steering mechanism 88. The power steering mechanism 88 changes the direction of the front wheels 10 which are the steering wheels of the traveling vehicle body 2. The planting clutch operating solenoid 83 operates the planting clutch 27a. When the planting clutch 27a is in the "engaged" state, the planting rotary 57 rotates and seedlings are planted by the planting rod 58. When the planting clutch 27a is in the "disengaged" state, the planting rotary 57 does not rotate and seedlings are not planted by the planting rod 58.

[0070] The side clutch operating solenoid 84 operates a side clutch 44 that switches the power transmission state to the rear wheels 11 (see FIG. 1). The side clutch 44 is provided on each of the left and right rear wheels 11, and two side clutch operating solenoids 84 are provided corresponding to each side clutch 44.

[0071] The HST motor 146 changes the tilt angle of the swash plate 148 of the HST 14 by changing the trunnion opening of the HST 14. The steering motor 95 is a motor that drives the steering wheel 35, which is a steering device that adjusts the steering amount (steering angle) of the front wheels 10 (see FIG. 1) when automatic turning control is performed. The steering motor 95 rotates the steering wheel 35. The line-drawing marker lifting motor 87 raises and lowers the line-drawing marker 65.

[0072] The differential lock switching motor 96 is a motor that switches the operation and the stop of the differential lock mechanism 97 (hereinafter referred to as the differential lock mechanism) that rotates the left and right traveling wheels, specifically, the left and right front wheels 10, at the same rotational speed. When the differential lock mechanism 97 is in the engaged state, the left and right traveling wheels rotate at the same rotational speed.

[0073] To the controller 100, a rotation speed sensor 90, a steering amount sensor 91, an inclination sensor 92, etc., which are detection devices, are connected. Two rotation speed sensors 90 are provided corresponding to the left and right rear wheels 11, and detect the rotation speeds of the left and right rear wheels 11 respectively. Note that the rotation speed sensor 90 may detect the rotation speeds of the left and right front wheels 10.

[0074] The steering amount sensor 91 detects the operation position of the steering wheel 35, which is a steering device, that is, the steering amount (steering angle) of the front wheels 10. The steering amount sensor 91 is provided, for example, on the shaft connected to the pitman arm. Note that the steering amount is detected in each of the left and right directions with the value when the steering wheel 35 is in the preset straight-ahead position as a reference value.

[0075] The inclination sensor 92 detects the inclination angle of the traveling vehicle body 2. The inclination sensor 92 detects the inclination angle of the traveling vehicle body 2 in the front-rear direction. The inclination sensor 92 is, for example, a G sensor.

[0076] In addition, signals are input into the controller 100 as operation signals from the main shift operation lever 36, sub-shift operation lever 37, setting switch 49, autonomous driving changeover switch 46, planting unit lift switch 47, automatic straight travel changeover switch 45, automatic turning changeover switch 48, and accelerator pedal 110, etc.

[0077] The autonomous driving changeover switch 46 is a switch for switching whether to execute autonomous driving. Specifically, the autonomous driving changeover switch 46 is a switch for switching the driving mode to a manual driving mode or an autonomous driving mode (automatic driving mode). The manual driving mode is a mode in which the vehicle travels by the manual operation of the operator. The autonomous driving mode is a mode in which the vehicle automatically travels without the manual operation of the operator.

[0078] For example, when the autonomous driving changeover switch 46 is "ON", the driving mode is set to the autonomous driving mode. When the autonomous driving changeover switch 46 is "OFF", the driving mode is set to the manual driving mode. When the autonomous driving changeover switch 46 is turned "ON", the automatic straight travel changeover switch 45 and the automatic turning changeover switch 48 are turned "ON". That is, when the driving mode becomes the autonomous driving mode, the automatic straight travel changeover switch 45 and the automatic turning changeover switch 48 can be changed to "OFF" by the operation of the operator even if they have once been turned "ON".

[0079] The planting unit lift switch 47 is a switch for switching whether to lift the seedling planting unit 4. The planting unit lift switch 47 is changed to the "raise" and "lower" positions.

[0080] When the planting unit lift switch 47 is in the "raise" position, the seedling planting unit 4 rises to a predetermined raised position, and the seedling planting device 55 enters a non-ground working state where it stops. When the seedling planting unit 4 is in the non-ground working state, the planting clutch 27a is in the "off" state.

[0081] When the planting unit lifting switch 47 is in the "lowering" position, the seedling planting unit 4 lowers to a predetermined lower position, and the seedling planting device 55 enters an operating state. That is, the planting unit lifting switch 47 is a switch that detects the operating state of the seedling planting unit 4. Note that a separate switch for detecting the operating state of the seedling planting unit 4 may be provided. When the seedling planting unit 4 enters the operating state, the planting clutch 27a enters the "engaged" state.

[0082] The automatic straight-ahead switching switch 45 is a switch that switches whether or not to enable the execution of automatic straight-ahead driving. When the automatic straight-ahead switching switch 45 is "ON", the running assist function described later becomes effective, and automatic straight-ahead driving can be executed. When the automatic straight-ahead switching switch 45 is "OFF", the running assist function becomes invalid, and automatic straight-ahead driving cannot be executed.

[0083] The automatic turning switching switch 48 is a switch that switches whether or not to enable the execution of automatic turning. When the automatic turning switching switch 48 is "ON", the turning assist function described later becomes effective, and automatic turning can be executed. When the automatic turning switching switch 48 is "OFF", the turning assist function becomes invalid, and automatic turning cannot be executed. When the automatic turning switching switch 48 is "OFF", even if the conditions for executing automatic turning are satisfied, automatic turning is not executed.

[0084] The controller 100 switches the driving mode between the manual driving mode and the autonomous driving mode according to the operations of the autonomous driving switching switch 46, the automatic straight-ahead switching switch 45, and the automatic turning switching switch 48.

[0085] In addition, current position information of the traveling vehicle body 2 and the like are input to the controller 100 from the position detection device 150. The controller 100 executes an autonomous driving mode in which the traveling vehicle body 2 performs work while automatically traveling.

[0086] The controller 100 has an autonomous driving mode (automatic driving mode) in which the steering motor 95 is controlled while feedbacking the steering amount of the front wheels 10 (see FIG. 1) to operate the steering wheel 35. The autonomous driving mode includes an automatic straight - running mode and an automatic turning mode.

[0087] The automatic straight - running mode is a mode in which the steering motor 95 is controlled so that the traveling vehicle body 2 travels along a preset straight - running path. In the automatic straight - running mode, while the seedlings are being planted in the field by the seedling planting unit 4, the traveling vehicle body 2 travels straight without depending on the operation of the operator. That is, while the traveling vehicle body 2 is automatically traveling straight, a traveling assist function for transplanting seedlings in the field becomes effective and the traveling assist function is executed.

[0088] In the automatic turning mode, when the traveling vehicle body 2 reaches a predetermined planting end position, the seedling planting by the seedling planting unit 4 is stopped, and the steering motor 95 is controlled so that the traveling vehicle body 2 travels along a preset turning path, and it is a turning mode. The predetermined planting end position is set, for example, by the traveling distance of the process in which the work is performed, the position information regarding the process in which the work is performed, and the like.

[0089] In the automatic turning mode, for example, the seedling planting unit 4 rises and is in a non - working state, and the traveling vehicle body 2 automatically turns without depending on the operation of the operator. That is, without performing the seedling planting by the seedling planting unit 4, a turning assist function for turning the traveling vehicle body 2 becomes effective and the turning assist function is executed.

[0090] In addition, various information is input to the controller 100 from a remote operation device 170 (hereinafter referred to as a "remote controller"). For example, the controller 100 receives various information from the remote controller 170 via a receiver 180 (see FIG. 1). The receiver 180 is attached to, for example, a mounting stand 59 (see FIG. 1) and is disposed above the front side of the traveling vehicle body 2. Note that a plurality of receivers 180 may be provided. The mounting stand 59 is attached to the traveling vehicle body 2.

[0091] The remote controller 170 can remotely operate the seedling transplanter 1. The remote controller 170 is a terminal device such as a smartphone. The remote controller 170 transmits a control signal according to the operator's operation. The remote controller 170 is communicably connected to the controller 100 by short-range wireless communication such as Wi-fi (registered trademark) or BLE (Bluetooth (registered trademark) Low Energy), but is not limited thereto, and may be communicably connected via a communication network or the like in addition to or instead of short-range wireless communication.

[0092] A plurality of remote controllers 170 may be provided. That is, the controller 100 may be able to acquire the position information of each remote controller 170 from a plurality of remote controllers 170. The remote controller 170 may be attachable to the seedling transplanter 1.

[0093] The controller 100 controls the vehicle speed of the traveling vehicle body 2 by controlling the rotational speed of the engine 30 and the trunion opening degree of the HST 14.

[0094] The controller 100 sets the vehicle speed mode to the first vehicle speed mode or the second vehicle speed mode according to the operation of the setting switch 49. That is, the controller 100 sets the trunion opening degree of the HST 14 to the first upper limit opening degree or the second upper limit opening degree according to the operation state of the setting switch 49.

[0095] When the vehicle speed mode is the first vehicle speed mode, the controller 100 controls the trunion opening degree of the HST 14 so that the vehicle speed of the traveling vehicle body 2 becomes the vehicle speed corresponding to the position (operation amount) of the main transmission operation lever 36. The controller 100 controls the trunion opening degree of the HST 14 while setting the trunion opening degree of the HST 14 as the first upper limit opening degree.

[0096] When the vehicle speed mode is the second vehicle speed mode, the controller 100 regulates the trunion opening degree of the HST 14 to the second upper limit opening degree. As a result, the vehicle speed of the traveling vehicle body 2 is limited to a lower vehicle speed compared to the case where the vehicle speed mode is the first vehicle speed mode. The rotational speed of the engine 30 is set according to the position of the main transmission operation lever 36.

[0097] With reference to FIG. 7, the relationship between the position of the main transmission operation lever 36, the trunion opening degree, and the rotational speed of the engine 30 when the vehicle speed mode is the second vehicle speed mode will be described. FIG. 7 is a diagram showing the relationship between the position of the main transmission operation lever 36, the trunion opening degree, and the rotational speed of the engine 30. In FIG. 7, for the sake of explanation, the trunion opening degree and the rotational speed of the engine 30 are described on the vertical axis. Also, in FIG. 7, the position of the main transmission operation lever 36 between the neutral region 812 (see FIG. 4) and the forward travel region 811 (see FIG. 4) is shown. Further, in FIG. 7, a part of the trunion opening degree in the first vehicle speed mode is indicated by a broken line.

[0098] When the vehicle speed mode is the first vehicle speed mode, as the position of the main transmission operation lever 36 moves from the neutral region 812 to the foremost side of the forward travel region 811, the trunion opening degree increases. Also, the rotational speed of the engine 30 increases.

[0099] On the other hand, when the vehicle speed mode is the second vehicle speed mode, when the position of the main transmission operation lever 36 moves from the neutral region 812 to the foremost side of the forward travel region 811, the trunion opening degree is regulated to the second upper limit opening degree. Since the rotational speed of the engine 30 increases, the vehicle speed of the traveling vehicle body 2 also changes as the rotational speed of the engine 30 changes. However, since the trunion opening degree is regulated to the second upper limit opening degree, the increase in the vehicle speed of the traveling vehicle body 2 is suppressed compared to the case where the vehicle speed mode is the first vehicle speed mode. That is, in the second vehicle speed mode, since the trunion opening degree is regulated, the vehicle speed of the traveling vehicle body 2 does not increase due to the trunion opening degree, but the vehicle speed of the traveling vehicle body 2 slightly increases because the rotational speed of the engine 30 increases.

[0100] Thus, when the vehicle speed mode is the second vehicle speed mode, the trunion opening is regulated to the second upper limit opening, thereby suppressing the vehicle speed of the traveling vehicle body 2. For example, when the main shift operation lever 36 is at the foremost position in the forward traveling region 811 and the vehicle speed mode is the first vehicle speed mode, the transplanter 1 can achieve high-speed traveling according to the position of the main shift operation lever 36. When the main shift operation lever 36 is at the foremost position in the forward traveling region 811 and the vehicle speed mode is the second vehicle speed mode, the transplanter 1 can achieve low-speed traveling with the trunion opening regulated.

[0101] Next, the upper limit opening setting process of the trunion opening according to the embodiment will be described with reference to FIG. 8. FIG. 8 is a flowchart showing the upper limit opening setting process of the trunion opening according to the embodiment.

[0102] The controller 100 determines whether the setting switch 49 is in the first position (S100). When the setting switch 49 is in the first position (S100: Yes), the controller 100 sets the upper limit opening of the trunion opening to the first upper limit opening (S101).

[0103] When the setting switch 49 is not in the first position (S100: No), that is, when the setting switch 49 is in the second position, the controller 100 sets the upper limit opening of the trunion opening to the second upper limit opening (S102).

[0104] The transplanter 1 includes an engine 30, an HST 14, a main shift operation lever 36, a setting switch 49, and a controller 100. The engine 30 is provided on the traveling vehicle body 2. The HST 14 shifts and outputs the power input from the engine 30. The main shift operation lever 36 can adjust the vehicle speed of the traveling vehicle body 2 by adjusting the trunion opening of the HST 14. The setting switch 49 accepts a change operation of the upper limit opening of the trunion opening of the HST 14 by the main shift operation lever 36. The controller 100 sets the upper limit opening of the trunion opening according to the operation state of the setting switch 49.

[0105] As a result, the seedling transplanter 1 can change the upper limit opening degree of the trunnion opening degree according to the operation of the setting switch 49. For example, when the seedling transplanter 1 is loaded onto a truck or moving on an inclined surface, by reducing the upper limit opening degree of the trunnion opening degree, the speed of the traveling vehicle body 2 can be suppressed, and fine adjustment can be performed regarding the traveling of the traveling vehicle body 2. Therefore, the seedling transplanter 1 can improve the safety of the operator.

[0106] In addition, the main transmission operation lever 36 can switch the forward and backward movement of the traveling vehicle body 2. The controller 100 sets the upper limit opening degree of the trunnion opening degree when the traveling vehicle body 2 is moving forward and backward according to the operation of the setting switch 49. The rotational speed of the engine 30 is set according to the operation amount of the main transmission operation lever 36.

[0107] As a result, the seedling transplanter 1 can set the upper limit opening degree of the trunnion opening degree suitable for forward movement and backward movement respectively. Therefore, the seedling transplanter 1 can perform fine adjustment regarding the traveling of the traveling vehicle body 2 during forward movement and backward movement respectively, and can improve the safety of the operator. In addition, the seedling transplanter 1 can set the rotational speed of the engine 30 according to the operation amount of the main transmission operation lever 36, for example, while increasing the rotational speed of the engine 30 on an inclined surface, regulate the trunnion opening degree, and stabilize the traveling of the traveling vehicle body 2.

[0108] In addition, the controller 100 sets the vehicle speed mode to a first vehicle speed mode in which the upper limit opening degree is a first upper limit opening degree or a second vehicle speed mode in which the upper limit opening degree is a second upper limit opening degree according to the operation of the main transmission operation lever 36. The second vehicle speed mode is a mode in which the speed of the traveling vehicle body 2 is lower than that of the first vehicle speed mode.

[0109] As a result, the seedling transplanter 1 can suppress the increase in the trunnion opening degree by setting the vehicle speed mode to the second vehicle speed mode, and can improve the safety of the operator.

[0110] Also, the first upper opening degree and the second upper opening degree are different opening degrees when the traveling vehicle body 2 is moving forward and when it is moving backward, respectively. The second upper opening degree when moving backward in the second vehicle speed mode is smaller than the second upper opening degree when moving forward in the second vehicle speed mode.

[0111] Thereby, the seedling transplanter 1 can further improve the safety of the operator when moving backward.

[0112] When changing the vehicle speed mode of the seedling transplanter 1 according to the modification example from the second vehicle speed mode to the first vehicle speed mode, the second vehicle speed mode is canceled on the condition that the main transmission operation lever 36 is in the neutral region 812. For example, when the main transmission operation lever 36 is not in the neutral region 812, even if the setting switch 49 is operated from the second position to the first position, the vehicle speed mode is maintained in the second vehicle speed mode.

[0113] Thereby, when the upper limit opening degree of the trunnion opening degree increases from the second upper limit opening degree to the first upper limit opening degree, the seedling transplanter 1 can suppress a rapid increase in the speed of the traveling vehicle body 2 and improve the safety of the operator.

[0114] The seedling transplanter 1 according to the modification example may execute the second vehicle speed mode on the condition that the seedling planting device 55 is in a predetermined non-ground working state. For example, when the seedling planting device 55 is in a working state, even if the setting switch 49 is operated from the first position to the second position, the vehicle speed mode does not become the second vehicle speed mode and is maintained in the first vehicle speed mode.

[0115] Accordingly, the seedling transplanter 1 suppresses the vehicle speed mode from becoming the second vehicle speed mode when the seedling planting device 55 is in the working state. When the vehicle speed mode is set to the second vehicle speed mode, for example, it is assumed that the traveling vehicle body 2 travels on an inclined surface such as being loaded on a truck. In such a case, if the seedling planting device 55 is in the working state, the seedling planting device 55 may hit the inclined surface and the seedling planting device 55 may deteriorate. The seedling transplanter 1 can suppress the deterioration of the seedling planting device 55 by executing the second vehicle speed mode on the condition that it is in a predetermined non-ground working state.

[0116] Note that the seedling transplanter 1 according to the modification example may execute the second vehicle speed mode on the condition that the float 62 is in a non-grounded state. The seedling transplanter 1 according to the modification example may execute the second vehicle speed mode on the condition that the sub-shift operation lever 37 is in the planting position.

[0117] The seedling transplanter 1 according to the modification example controls the speed of the traveling vehicle body 2 by controlling the output of the HST 14 and the rotation speed of the engine 30 by operating either one of the main shift operation lever 36 and the accelerator pedal 110. Also, the seedling transplanter 1 controls the rotation speed of the engine 30 by operating the other one of the main shift operation lever 36 and the accelerator pedal 110. When the vehicle speed mode is set to the second vehicle speed mode according to the operation of the setting switch 49, the upper limit of the output of the HST 14 is set by operating the main shift operation lever 36 and the accelerator pedal 110.

[0118] As a result, the seedling transplanter 1 can control the output of the HST 14 and the rotational speed of the engine 30 by operating either the main speed change operation lever 36 or the accelerator pedal 110. Further, the seedling transplanter 1 can control the rotational speed of the engine 30 by operating the other of the main speed change operation lever 36 and the accelerator pedal 110. Therefore, since the control targets for the operations of the main speed change operation lever 36 and the accelerator pedal 110 are different, the operator can distinguish the control target that the operator desires to control by operating the main speed change operation lever 36 and the accelerator pedal 110. Accordingly, the seedling transplanter 1 can improve the operability of the operator. Also, when the vehicle speed mode is the second vehicle speed mode, the output of the HST 14 can be regulated by operating the main speed change operation lever 36 and the accelerator pedal 110, and the safety of the operator can be improved.

[0119] The seedling transplanter 1 according to the modification may set the vehicle speed mode based on the inclination angle in the longitudinal direction of the traveling vehicle body 2 detected by the inclination sensor 92.

[0120] For example, when the inclination angle detected by the inclination sensor 92 is equal to or greater than a first predetermined angle (predetermined angle), the controller 100 sets the vehicle speed mode to the second vehicle speed mode. That is, when the inclination angle is equal to or greater than the first predetermined angle, the controller 100 automatically sets the upper limit opening of the trunnion opening to the second upper limit opening. The first predetermined angle is a preset angle and is an angle at which it can be determined that the traveling vehicle body 2 is on an inclined surface.

[0121] Further, when the inclination angle becomes less than the first predetermined angle while the vehicle speed mode is in the second vehicle speed mode, the controller 100 maintains the vehicle speed mode in the second vehicle speed mode. That is, when the vehicle speed mode is the second vehicle speed mode, the controller 100 maintains the vehicle speed mode in the second vehicle speed mode even if the inclination angle becomes small and less than the first predetermined angle.

[0122] When the vehicle speed mode is in the second vehicle speed mode and the main shift operation lever 36 enters the neutral range 812, or when the depression of the accelerator pedal 110 ceases, the controller 100 releases the second vehicle speed mode. That is, when the vehicle speed mode is in the second vehicle speed mode and the main shift operation lever 36 enters the neutral range 812, or when the depression of the accelerator pedal 110 ceases, the vehicle speed mode changes from the second vehicle speed mode to the first vehicle speed mode.

[0123] Thereby, when the inclination angle of the transplanter 1 becomes equal to or greater than the first predetermined angle, the vehicle speed mode is set to the second vehicle speed mode, so that when traveling on an inclined surface, the upper limit opening of the trunnion opening is set to the second upper limit opening, and the safety of the operator can be improved. Further, when the main shift operation lever 36 enters the neutral range 812 or when the operation of the accelerator pedal 110 ceases, the transplanter 1 changes the vehicle speed mode to the first vehicle speed mode, can suppress a rapid increase in the speed of the traveling vehicle body 2, and can improve the safety of the operator.

[0124] Note that the first predetermined angle may be changeable. The first predetermined angle can be set by an operator or the like. Thereby, the operator can set the first predetermined angle according to the inclined surface such as the angle of the footboard used when loading the transplanter 1 onto a truck, for example. For example, the first predetermined angle may be set in 0.1-degree units up to 15 degrees.

[0125] The controller 100 of the seedling transplanter 1 according to the modified example may have an angle setting mode for setting a first predetermined angle. The ON and OFF of the angle setting mode are set by the operator. The seedling transplanter 1 is provided with a switch or the like for switching the angle setting mode. When the angle setting mode is ON, the controller 100 sets the angle measured by the inclination sensor 92 when the traveling vehicle body 2 enters the field to the first predetermined angle. For example, the controller 100 determines whether the traveling vehicle body 2 has entered the field based on the position information detected by the position detection device 150. Further, when the angle setting mode is ON and the seedling transplanter 1 moves from an inclined surface to a flat ground, the controller 100 may set the angle on the inclined surface to the first predetermined angle.

[0126] Thereby, the seedling transplanter 1 can set the first predetermined angle according to the field.

[0127] For example, in FIG. 9, when the seedling transplanter 1 according to the modified example sets a work area by traveling along the ridges of the field (routes La, Lb, Lc), the azimuth during traveling on route La may be used as the azimuth of the reference line in the work area. FIG. 9 is a diagram showing an example of a method for setting a work area. The work area is, for example, an area where work can be performed by autonomous traveling, that is, straight-ahead assist and turning assist.

[0128] When the traveling mode of the controller 100 of the seedling transplanter 1 according to the modified example is the automatic traveling mode and the inclination angle is equal to or greater than the first predetermined angle, the controller 100 deletes the reference data for automatic traveling. The reference data includes information such as the azimuth of the reference line, the straight-ahead route that serves as a reference for automatic straight-ahead traveling in the field, the traveling distance of the process in which work has been performed, and the position information regarding the process in which work has been performed.

[0129] Thereby, when the work in the field is completed and the seedling transplanter 1 is taken out of the field, the seedling transplanter 1 can automatically delete the reference data of the field where the work has been performed. Therefore, the seedling transplanter 1 can prevent incorrect reference data from being used and automatic traveling from being executed in other fields.

[0130] When the seedling transplanter 1 according to the modification example is in the second vehicle speed mode and the inclination angle is equal to or greater than the second predetermined angle, the trunnion opening may be changed so that the torque is low and the engine speed 30 increases. For example, the seedling transplanter 1 reduces the trunnion opening.

[0131] When the vehicle speed mode of the seedling transplanter 1 according to the modification example is changed to the first vehicle speed mode and the second vehicle speed mode, it may be changed to the first vehicle speed mode and the second vehicle speed mode respectively through the shift preparation mode. Thereby, the seedling transplanter 1 can suppress a sudden change in vehicle speed when the vehicle speed mode is switched.

[0132] For example, when the vehicle speed mode is changed from the second vehicle speed mode to the first vehicle speed mode, in the shift preparation mode, the vehicle speed is regulated in the same manner as in the second vehicle speed mode, and the vehicle speed mode is changed to the first vehicle speed mode under specific conditions. The specific conditions are, for example, the condition that the main shift operation lever 36 is in the neutral region 812. The specific condition is the condition that the seedling planting unit 4 is not in the predetermined lowered position.

[0133] When the vehicle speed mode is changed from the first vehicle speed mode to the second vehicle speed mode, in the shift preparation mode, there is no vehicle speed regulation, and the vehicle speed mode is changed to the second vehicle speed mode under specific conditions. The specific conditions are, for example, the condition that the main shift operation lever 36 is in the neutral region 812. The specific condition is the condition that the sub-shift operation lever 37 is in the position for planting speed.

[0134] When changing the vehicle speed mode, the seedling transplanter 1 according to the modification example may sound an alarm or display on the monitor 86. Further, the seedling transplanter 1 according to the modification example may turn on the lamp of the center mascot 66.

[0135] For the seedling transplanter 1 according to the modification example, when the setting switch 49 is in the second position, the main speed change operation lever 36 is in the neutral region 812, the sub-speed change operation lever 37 is at the planting speed, the planting clutch 27a is in the disengaged state, the float 62 is in the non-grounded state, and the safety switch is OFF (for example, the parking pedal is not depressed), the vehicle speed mode may be set to the second vehicle speed mode.

[0136] For the seedling transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, if the setting switch 49 is in the first position, the main speed change operation lever 36 is in the neutral region 812, and the trunion of the HST 14 is in the neutral position, the vehicle speed mode may be set to the first vehicle speed mode.

[0137] For the seedling transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, it may be configured not to accept the engagement operation of the planting clutch 27a. For the seedling transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, it may be configured not to accept the raising operation of the seedling planting unit 4. For the seedling transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, it may be configured not to accept the lowering operation of the seedling planting unit 4. For the seedling transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, it may be configured not to accept the control to raise the seedling planting unit 4 when the traveling vehicle body 2 moves backward. For the seedling transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, it may be configured not to accept the control to slightly lower the seedling planting unit 4.

[0138] For the seedling transplanter 1 according to the modification example, when the main speed change operation lever 36 or the sub-speed change operation lever 37 is operated, the HST 14 may be set to the neutral position. Thereby, the seedling transplanter 1 can suppress sudden acceleration due to misoperation.

[0139] For the seedling transplanter 1 according to the modification example, when a micro-speed switch different from the setting switch 49 is ON, the main speed change operation lever 36 is in the neutral region 812, it is not in the pita alignment control, not in the pita planting control, not in the straight line assist, and not in the turning assist, the vehicle speed mode may be set to the second vehicle speed mode.

[0140] In the transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, the pita alignment control may not be performed. In the transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, the pita planting control may not be performed. In the transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, the straight-ahead assist control may not be performed. In the transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode, the turning assist control may not be performed.

[0141] In the transplanter 1 according to the modification example, when the creep switch is OFF and the main shift operation lever 36 is in the neutral region 812, the vehicle speed mode may be set to the first vehicle speed mode.

[0142] In the transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode and, when moving forward, the target vehicle speed by the main shift operation lever 36 exceeds the vehicle speed that is 20% of the vehicle speed in the first vehicle speed mode, a warning sound may be emitted by a buzzer or the like. In the transplanter 1 according to the modification example, the vehicle speed to be regulated when the vehicle speed mode is the second vehicle speed mode may be changeable on the setting screen of the monitor 86.

[0143] In the transplanter 1 according to the modification example, when the vehicle speed mode is the second vehicle speed mode and, when moving backward, the target vehicle speed by the main shift operation lever 36 exceeds the vehicle speed that is 30% of the vehicle speed in the first vehicle speed mode, a warning sound may be emitted by a buzzer or the like. In the transplanter 1 according to the modification example, the vehicle speed to be regulated when the vehicle speed mode is the second vehicle speed mode may be changeable on the setting screen of the monitor 86.

[0144] In the transplanter 1 according to the modification example, the vehicle speed mode may be set to the second vehicle speed mode while the creep switch is being pressed.

[0145] The seedling transplanter 1 according to the modified example may be provided with a low-speed switch for forward movement and a low-speed switch for reverse movement. When neither the low-speed switch for forward movement nor the low-speed switch for reverse movement of the seedling transplanter 1 according to the modified example is pressed, the HST 14 may be set to the neutral position. When the low-speed switch for forward movement and the low-speed switch for reverse movement of the seedling transplanter 1 according to the modified example are pressed, the HST 14 may be set to the neutral position.

[0146] When the HST motor 146 operates on the acceleration side by operating the low-speed switch of the seedling transplanter 1 according to the modified example, the response of the HST motor 146 may be made slower (smaller acceleration) compared to the normal lever operation.

[0147] When the HST 14 is set to the neutral position in the seedling transplanter 1 according to the modified example, the response of the HST motor 146 may be made slower (smaller acceleration) compared to the normal lever operation.

[0148] That is, since the trunnion opening amount with respect to the lever operation amount is different between the first vehicle speed mode and the second vehicle speed mode, when the same lever operation amount is used in the second vehicle speed mode and the first vehicle speed mode, the vehicle speed in the second vehicle speed mode is slower than that in the first vehicle speed mode. Therefore, the acceleration can be reduced, and the vehicle can be accelerated slowly with respect to the operation amount, improving safety.

[0149] The seedling transplanter 1 according to the modified example may increase the rotational speed of the engine 30 according to the trunnion opening of the HST 14. For example, the seedling transplanter 1 does not control the rotational speed of the engine 30 only according to the position of the main transmission operation lever 36, but also controls the rotational speed of the engine 30 according to the trunnion opening of the HST 14.

[0150] Thereby, when the vehicle speed mode of the seedling transplanter 1 is the second vehicle speed mode, an increase in the rotational speed of the engine 30 is suppressed, and fine adjustment of the vehicle speed becomes possible.

[0151] Further effects and modifications can be easily derived by those skilled in the art. For this reason, the broader aspects of the present invention are not limited to the specific details and representative embodiments presented and described as above. Therefore, various changes can be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

Explanation of Signs

[0152] 1 Seedling transplanter (work vehicle) 2 Traveling vehicle body 4 Seedling planting unit (work device) 14 HST (continuously variable transmission, hydraulic continuously variable transmission) 30 Engine 35 Steering wheel (steering device) 36 Main transmission operation lever (operating tool, first operating tool) 49 Setting switch (setting tool) 55 Seedling planting device 92 Tilt sensor 95 Steering motor (motor) 100 Controller (control device) 110 Accelerator pedal (operating tool, second operating tool) 150 Position detection device (position information acquisition device)

Claims

1. An engine provided on a traveling vehicle body, a hydraulic continuously variable transmission that changes and outputs the power input from the engine, an operating tool capable of adjusting the vehicle speed of the traveling vehicle body by adjusting the trinion opening degree of the hydraulic continuously variable transmission, wherein the rotational speed of the engine is set according to the operation amount of the operating tool, a setting tool that accepts a change operation of the upper limit opening degree of the trinion opening degree of the hydraulic continuously variable transmission by the operating tool, a control device that sets the upper limit opening degree of the trinion opening degree according to the operation state of the setting tool, In a state where the upper limit of the trinion opening degree is reached, when the operating tool is further operated, the engine speed increases, and for vehicle speed adjustment above the upper limit of the trinion opening degree, the vehicle speed can be increased by the increase in the engine speed. A work vehicle characterized by this.

2. The control device sets the vehicle speed mode to a first vehicle speed mode in which the upper limit opening degree is a first upper limit opening degree or a second vehicle speed mode in which the upper limit opening degree is a second upper limit opening degree according to the operation of the setting tool, The work vehicle according to claim 1, wherein the second vehicle speed mode is a mode in which the speed of the traveling vehicle body is lower than that of the first vehicle speed mode.

3. The trinion opening degree with respect to the operation amount of the operating tool is different between the first vehicle speed mode and the second vehicle speed mode, The work vehicle according to claim 1 or 2, characterized in that when the operating tool is set to the same operation amount in the second vehicle speed mode and the first vehicle speed mode, the trinion opening degree is smaller in the second vehicle speed mode.

Images