Work vehicle

Abstract

To provide a work vehicle that facilitates an operation of travel at a slow speed in comparison to conventional techniques.SOLUTION: A work vehicle includes: a hydraulic continuously variable transmission for shifting power from an engine 12 by adjusting an opening degree of a trunnion shaft; an operation tool 62 for performing an operation to adjust the opening degree of the trunnion shaft; and a changing tool 63 for performing an operation to change an upper limit of the opening degree of the trunnion shaft. On the basis of an operation state of the changing tool 63 for performing the operation to change the upper limit of the opening degree of the trunnion shaft, the control unit 300 controls the upper limit of the opening degree of the trunnion shaft, and the operation tool 62 performs the operation to adjust the opening degree of the trunnion shaft, thereby facilitating an operation of travel at a slow speed in comparison to conventional techniques.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This invention relates to work vehicles such as rice transplanters and tractors.

Background Art

[0002] In work vehicles such as rice transplanters and tractors, when it is desired to travel at a very low speed, such as when loading and unloading the work vehicle onto a truck or entering and leaving a field, there is a known technique of setting the maximum speed when the shift pedal is depressed to the limit with an operating tool such as a maximum speed setting dial (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the techniques described in Patent Documents 1 and 2, even when the maximum speed is limited to a very low speed, an operation of depressing the shift pedal is required, and it is necessary to travel while seated. The pedal operation is a foot operation, which is difficult to finely adjust, and the shift pedal installed on the floor step where operations such as seedling replenishment work are performed may induce accidents such as tripping and falling, and there is also a problem of hindering work. Also, when traveling at a very low speed during storage in a shed, loading onto a truck, crossing a ridge, etc., there is little margin in the gap with the ceiling, the slope is large, or there is significant vertical sway when crossing a ridge, etc., resulting in uneasiness in the operation while seated, or the foot easily leaves the shift pedal and operation errors are likely to occur.

[0005] The technical problem of the present invention is to provide a work vehicle that is easier to operate for traveling at a very low speed compared to the prior art.

Means for Solving the Problem

[0006] The above problems of the present invention are solved by the following solution means. The invention according to claim 1 is a work vehicle comprising: an engine (12) mounted on a vehicle body (1); a hydraulic continuously variable transmission that changes the power from the engine (12) by adjusting the opening degree of a trunnion shaft; an operating tool (62) that performs an operation of adjusting the opening degree of the trunnion shaft; a changing tool (63) that performs an operation of changing the upper limit of the opening degree of the trunnion shaft; and a control unit (300) that controls the upper limit of the opening degree of the trunnion shaft based on the operating state of the changing tool (63).

[0007] The invention according to claim 2 is a work vehicle according to claim 1, further comprising: a working machine (3) provided on the vehicle body (1) for performing work in a field; and the control unit (300) that controls the opening degree of the trunnion shaft to the limit value when the changing tool (63) performs an operation of limiting the upper limit of the opening degree of the trunnion shaft to a limit value lower than a predetermined reference value in a state where an operation for stopping the vehicle body (1) is performed, the vehicle body (1) has stopped running, and the working machine (3) has stopped.

[0008] The invention according to claim 3 is a work vehicle according to claim 1, further comprising: an inclination measuring member (SN1b) that measures the inclination of the vehicle body (1); and the control unit (300) that, when the operating tool (62) is operated in a state where the opening degree of the trunnion shaft is controlled to a limit value lower than a predetermined reference value, runs the vehicle body (1) within the range of the limit value, and after the inclination angle of the vehicle body (1) in the front-rear direction reaches a first angle predetermined during running within the range of the limit value, releases the control for limiting the upper limit of the opening degree of the trunnion shaft to the limit value when the inclination angle of the vehicle body (1) in the front-rear direction no longer reaches the first angle.

[0009] The invention according to claim 4 is the work vehicle according to claim 1, characterized in that it includes the control unit (300) that releases control for restricting the upper limit of the opening degree of the trunnion shaft to a limit value lower than a predetermined reference value when the work machine (3) becomes in a state where work can be started.

[0010] The invention according to claim 5 is the work vehicle according to claim 1, characterized in that it includes the operating tool (62) that enables an operation to adjust the opening degree of the trunnion shaft from outside the vehicle body (1) in a state where the vehicle body (1) is not occupied, and the changer (63) arranged near the operating tool (62). The changer (63) is operable between a forward position that restricts the upper limit of the opening degree of the trunnion shaft when the vehicle body (1) moves forward to a limit value lower than a predetermined reference value, a reverse position that restricts the upper limit of the opening degree of the trunnion shaft when the vehicle body (1) moves backward to the limit value, and a neutral position that stops the vehicle body (1). When the hand leaves the changer (63) during the operation to the forward position or the reverse position, the changer (63) automatically returns to the neutral position.

[0011] The invention according to claim 6 is the work vehicle according to claim 1, characterized in that it includes a work machine (3) composed of a seedling planting device (3) having a seedling tank (39) for accommodating seedlings and a seedling planting tool (41) for planting seedlings in a field, a number changer (501) for changing the number of times of reciprocating movement of the seedling tank (39) in the width direction of the vehicle body (1), an interlocking part (503) movable in conjunction with an interlocked part (502) provided on the number changer (501), an interlocking position detecting member (506) for detecting the position of the interlocking part (503), and a driving device (504) for changing the number of reciprocating movements by moving the number changer (501) by moving the interlocking part (503) according to the number of reciprocating movements.

[0012] The invention according to claim 7 is a work vehicle comprising: a seedling tank (39) for accommodating seedlings; a seedling planting tool (41) for planting seedlings in a field; a soil tilling rotor (21) for contacting the field and tilling the soil; a float (6) for contacting the field and leveling the field; a work implement (3) composed of the seedling planting device (3); a lifting device (36) for lifting and lowering the work implement (3) based on the variation of the float (6) contacting the field; a sensitivity adjuster (SW2) for adjusting the sensitivity of the variation of the float (6); and a control unit (300) for lowering the height of the soil tilling rotor (21) when the sensitivity is adjusted to the sensitive side by the sensitivity adjuster (SW2) as compared to when adjusted to the insensitive side, which is the work vehicle according to claim 1, characterized in that it is provided with these components.

Effect of the Invention

[0013] According to the invention described in claim 1, based on the operating state of a changer (63) that performs an operation to change the upper limit of the opening degree of the trunnion shaft, the control unit (300) controls the upper limit of the opening degree of the trunnion shaft, and by performing an operation to adjust the opening degree of the trunnion shaft with an operating tool (62), it is possible to provide a work vehicle that is easier to operate for traveling at a very low speed compared to the prior art.

[0014] According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, when the changer (63) performs an operation to limit the upper limit of the opening degree of the trunnion shaft to a limit value in a state where the vehicle body (1) has been operated to stop traveling, the vehicle body (1) has stopped traveling, and the work implement (3) has stopped, the control unit (300) controls the opening degree of the trunnion shaft to the limit value, so that the upper limit of the opening degree of the trunnion shaft can be limited to the limit value in a safe situation.

[0015] According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, when the inclination angle reaches a first angle and then no longer reaches the first angle during traveling within the range of the limit value, by canceling the control to limit the upper limit of the opening degree of the trunnion shaft to the limit value, there is no need to perform an operation to cancel it, and the next operation can be smoothly shifted to.

[0016] According to the invention described in claim 4, in addition to the effects of the invention described in claim 1, when the working machine (3) becomes in a state where work can be started, by canceling the control that restricts the opening degree upper limit of the trunnion axis to a limit value lower than a predetermined reference value, it becomes unnecessary to perform the canceling operation, and the work on the working machine (3) can be smoothly shifted to.

[0017] According to the invention described in claim 5, in addition to the effects of the invention described in claim 1, the operating tool (62) can be operated from the outside of the vehicle body (1). Also, with the changing tool (63), forward, reverse, and neutral can be switched. Furthermore, when the hand leaves the changing tool (63) during operation in the forward position or the reverse position, it automatically returns to the neutral position, thereby improving safety.

[0018] According to the invention described in claim 6, in addition to the effects of the invention described in claim 1, an interlocking part (503) that can move in conjunction with an interlocked part (502) provided on the number changing tool (501), an interlocking position detecting member (506) that detects the position of the interlocking part (503), and by the drive device (504) moving the interlocking part (503) according to the number of reciprocating movements to move the number changing tool (501) and change the number of reciprocating movements, compared with the conventional configuration that only manually changes the number of reciprocating movements, the number of reciprocating movements can be easily changed.

[0019] According to the invention described in claim 7, in addition to the effects of the invention described in claim 1, when the sensitivity is adjusted to the sensitive side with the sensitivity adjusting tool (SW2), by lowering the height of the leveling rotor (21) compared to the case of adjusting to the insensitive side, the height of the leveling rotor (21) can be stabilized.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying out the Invention

[0021] Embodiments of the present invention will be described below. An example of the work vehicle of the present invention, a four-row riding rice transplanter which is an example of a seedling transplanter, will be described in detail with reference to the drawings. FIG. 1 is a side view of the riding rice transplanter according to the embodiment. FIG. 2 is a plan view of the riding rice transplanter according to the embodiment. As shown in the side view of FIG. 1 and the plan view of FIG. 2, the riding rice transplanter is configured to mount a seedling planting device 3, which is a type of working machine, on a traveling vehicle (an example of the vehicle body) 1 via a lifting link device 2 and to be provided with a fertilizer application device 4 so as to function as a riding fertilizer rice transplanter as a whole. The traveling vehicle 1 is a four-wheel drive vehicle having a pair of left and right front wheels 8, 8 and a pair of left and right rear wheels 7, 7 which are drive wheels. In this specification, the left and right sides are referred to as the left side and the right side respectively toward the forward direction of the rice transplanter, the forward direction is referred to as the front side, and the reverse direction is referred to as the rear side.

[0022] As shown in Fig. 1, a transmission case 11 and an engine (internal combustion engine) 12 are arranged on main frames 10a and 10b, a hydraulic pump 13 is integrally assembled with the transmission case 11 on the rear side surface of the transmission case 11, and a steering post 14 projects upward in front of the transmission case 11. And a steering wheel 16 is provided at the upper end of the steering post 14. A step floor 19 serving as a floor for operation is attached to the upper part of the machine body, and a driver's seat 20 is installed above the engine 12. A shift operation lever (travel operation member, HST lever) 17 is provided on the right side of the steering wheel 16.

[0023] An operation panel (not shown) is provided on the steering post 14 in front of the driver's seat 20. A ridging clutch lever 18 is provided on the right side of the driver's seat 20. The front wheels 8 and 8 are pivotally supported by front wheel support cases 22 and 22 provided on the side of the transmission case 11 so that the direction can be changed. The rear wheels 7 and 7 are pivotally supported via rear wheel support bodies 30 by rear wheel transmission cases 24 and 24 attached to the left and right ends of the left and right frames 37. The left and right frames 37 are supported at the rear ends of the main frames 10a and 10b.

[0024] As shown in Figs. 1 and 2 for a part of the power transmission mechanism to the rear wheels 7, the rotational power of the engine 12 is transmitted to the input shaft 32a of a hydrostatic transmission (HST) 31 via a pulley 27, a belt 28, and a pulley 29 in sequence, and is transmitted into the transmission case 11 from the output shaft 32b of the HST 31. The rear ends of the rear output shafts 11a and 11b project to the rear of the transmission case 11, and left and right rear wheel transmission shafts 35 and 35 for transmitting power to the rear wheel transmission cases 24 and 24 are connected to the projecting end portions. The left and right rear wheels 7 and 7 are driven to rotate by the left and right rear wheel transmission shafts 35 and 35 respectively.

[0025] The seedling planting device 3 is mounted on the traveling vehicle 1 via a lifting link device 2 so as to be liftable. As an example of a general lifting device in which the base is rotatably provided on the traveling vehicle 1, the upper end of the piston of the lift cylinder 36 (Fig. 1) is connected to the lifting link device 2, and the hydraulic pump 13 provided on the traveling vehicle 1 supplies and discharges pressure oil to the lift cylinder 36 via a lift valve (not shown), and the piston of the lift cylinder 36 is extended and retracted so that the seedling planting device 3 connected to the lifting link device 2 moves up and down.

[0026] The seedling planting device 3 includes a planting transmission case 38 that also serves as a frame that is rotatably mounted on the rear part of the lifting link device 2 via left and right frames 37, a seedling stage (seedling tank) 39 that is supported by a support member provided on the planting transmission case 38 and reciprocates in the left-right direction of the machine body, a seedling planting tool 41 that is mounted on the rear end of the planting transmission case 38 and plants seedlings one by one from the lower end of the seedling stage 39 in the field, and a center float (sensor float) 6(6a) and a side float 6(6b) which are leveling bodies whose rear parts are pivotally supported at the lower part of the planting transmission case 38 and whose front parts are mounted so as to be swingable up and down. The center float 6a and the side float 6b are provided to level the field and level the front of the field where the seedlings are planted by the seedling planting tool 41.

[0027] The PTO drive shaft 45 (Fig. 1) has universal joints at both ends and is provided to transmit the power from the transmission case 11 to the planting transmission case 38 of the seedling planting device 3. The seedling planting device 3 is configured for four-row planting, and includes a planting transmission case 38 that also serves as a frame, a seedling stage 39 that places seedlings and reciprocates left and right to supply the seedlings one by one to each row of seedling outlets 39a (Fig. 2), a seedling planting tool 41 that plants the seedlings supplied to the seedling outlets 39a in the field, and the like.

[0028] As shown in Fig. 1, a soil tilling rotor 21(21a) for tilling the field is arranged in front of the center float 6(6a), and the soil tilling rotor 21(21a) is arranged further forward than the soil tilling rotor 21(21b) in front of the side float 6(6b). The power of the soil tilling rotor 21a is transmitted from the gear in the rear wheel transmission case 24 of the rear wheel 7 via the transmission shaft 25, and the power of the soil tilling rotor 21b is transmitted from a pair of chains (not shown) in a pair of chain cases 71, 71 on the left and right, respectively, from the drive shafts (not shown) of both rotors 21a, 21a.

[0029] The rear wheel transmission case 24 of the rear wheel 7 is attached to the left and right ends of the left and right frames 37 and is pivotally supported by the rear wheel support 30. By the rotation of the rear wheel transmission case 24, the axle 23 of the rear wheel 7 moves up and down integrally with the rear wheel transmission case 24. The power is transmitted to the rear wheel transmission case 24 from the transmission case 11 via the left and right rear wheel transmission shafts 35.

[0030] The fertilizer applicator 4 feeds the fertilizer in the fertilizer tank 67 downward by a certain amount by the fertilizer feeding section 68, transfers the fed fertilizer to the fertilizer guide 80 through the fertilizer hose 70 by the blower 69, and drops it into the fertilizer groove formed near the side of the seedling planting strip by the furrowing body 82 provided on the front side of the fertilizer guide 80. Also, the pedal 86(Fig. 2) can operate both the main clutch and the left and right rear wheel brake devices (not shown), and is arranged on the lower right side of the steering handle 16. When this pedal 86 is depressed, the main clutch is disengaged, and subsequently, the left and right rear wheel brakes are applied, and the machine body stops.

[0031] Fig. 3 is an explanatory view of the ridge crossing handle of the embodiment. Fig. 3(A) is an overall explanatory view of the ridge crossing handle, and Fig. 3(B) is an enlarged view of the micro speed switch. At the front of the traveling vehicle 1, a ridge-crossing handle 61 is supported. In FIG. 3, the ridge-crossing handle 61 of the embodiment is composed of a U-shaped pipe extending obliquely upward in front of the traveling vehicle 1. The ridge-crossing handle 61 can be pushed up and down in a state where an operator reaches around to the front of the traveling vehicle 1 and grabs it (non-riding state) to incline the posture of the traveling vehicle 1 forward or backward. Therefore, when the traveling vehicle 1 crosses a convex part such as a ridge, it is possible to assist in smooth crossing.

[0032] A travel lever 62, which is an example of an operating tool, is supported by the ridge-crossing handle 61. Also, in the vicinity of the travel lever 62, a micro speed switch 63, which is an example of a changing tool, is arranged. The micro speed switch 63 of the embodiment is a switch that switches between three positions: a forward position that limits the maximum speed during forward movement to a predetermined forward limit speed (first limit speed), a reverse position that limits the maximum speed during reverse movement to a predetermined reverse limit speed (second limit speed), and a neutral position that stops the traveling vehicle 1 without transmitting drive. In the micro speed switch 63 of the embodiment, the forward position is arranged on the front side with respect to the front-rear direction of the traveling vehicle 1, and the reverse position is arranged on the rear side, which is intuitive and easy for the operator to understand. Note that the forward limit speed and the reverse limit speed are set to a low speed (micro speed) at which the operator can safely respond even when the traveling vehicle 1 moves in a state where the operator reaches around to the front of the traveling vehicle 1. Also, in the embodiment, the forward limit speed and the reverse limit speed are set to the same speed, but it is also possible to set different speeds.

[0033] In addition, the fine speed switch 63 in the embodiment is a switch (so-called momentary switch) that is operated at the forward position or the reverse position while being pushed to the forward position or the reverse position by a finger or a hand, and returns to the neutral position when the finger is released. Note that the fine speed switch 63 preferably employs a momentary switch, but is not limited thereto. It is also possible to use a switch that does not return to the neutral position. Further, when the reverse position is not required, it is also possible to use a switch with only two positions, the forward position and the neutral position. Moreover, any switch can be adopted, such as a switch in which "forward", "neutral", and "reverse" are switched each time the button is pressed, or a switch that switches to "forward" when pressed briefly and switches to "reverse" when pressed and held for a long time.

[0034] In the seedling transplanter of the embodiment, by holding the travel lever 62 while pressing the forward position or the reverse position with a finger on the fine speed switch 63, the traveling vehicle 1 can start traveling at the forward limit speed or the reverse limit speed. Therefore, in the seedling transplanter of the embodiment, the traveling vehicle 1 does not travel even if the travel lever 62 is held when the fine speed switch 63 is not being operated, and when the finger is released from the fine speed switch 63, the fine speed switch 63 automatically returns to the neutral position, and the seedling transplanter stops traveling even if the travel lever 62 is continuously held. Note that even if the finger is released from the fine speed switch 63, it is also possible to adopt a mode in which the traveling vehicle 1 is not immediately stopped, and the traveling vehicle 1 continues to travel when the fine speed switch 63 is pressed again within a predetermined time. By doing so, even if the finger slips off the fine speed switch 63 or the like and the finger is accidentally released, the traveling vehicle 1 does not stop immediately, so the workability is improved.

[0035] In addition, after operating the fine speed switch 63 to the forward position or the reverse position, even if the finger is released, if the travel lever 62 is held within a predetermined time, by controlling to perform fine-speed forward or reverse travel, it is not necessary to continuously press the fine speed switch 63, and it is also possible to improve the operability and workability.

[0036] In addition, during extremely low-speed driving, it is preferable to activate notification means such as a buzzer, a lit lamp, and voice guidance in order to notify the surroundings that the vehicle is in extremely low-speed driving. In addition, it is desirable to install a sensor that detects seating in the driver's seat 20 and configure it so that the traveling lever 62 and the extremely low-speed switch 63 cannot be operated when seating is detected. That is, it is desirable to configure the traveling vehicle 1 so that it does not travel even if the traveling lever 62 or the extremely low-speed switch 63 is operated. In addition, when the traveling lever 62 is operated, although an example is shown in which the control unit 300 (described later) transmits a control signal to the HST for control, it is not limited to this. For example, it is also possible to directly connect the traveling lever 62 and the HST with a cable or the like and directly operate the HST when the traveling lever 62 is operated. In this mode, it is possible to change the vehicle speed according to the amount of gripping of the traveling lever 62.

[0037] (Description of the control unit of the seedling transplanter) FIG. 4 is a functional block diagram of the control unit of the embodiment. The seedling transplanter of the embodiment has a control unit 300 that controls each function. The control unit 300 has an input / output interface I / O that performs input / output of signals with the outside. In addition, the control unit 300 has a ROM: read-only memory in which programs and information for performing necessary processing are stored. In addition, the control unit 300 has a RAM: random access memory for temporarily storing necessary data. In addition, the control unit 300 has a CPU: central processing unit that performs processing according to the programs stored in the ROM and the like. Therefore, the control unit 300 of the embodiment is configured by a small information processing device, so-called microcomputer. Therefore, the control unit 300 can realize various functions by executing the programs stored in the ROM and the like.

[0038] The control unit 300 receives signals from signal input elements such as a high-mount monitor (not shown) composed of a touch panel, which is an example of an input unit and an example of a display unit, a positioning device SN1, an HST lever 33, a traveling lever 62, a creep switch 63, a planting switch SW1, a hydraulic pressure sensitivity switch SW2, a float angle sensor SN2, a straight-ahead assist start switch SW3, and various other sensors (not shown).

[0039] The positioning device SN1 includes a GNSS (Global Navigation Satellite System) receiver SN1a and an IMU (Inertial Measurement Unit, an example of an inclination measurement member) SN1b. The GNSS receiver SN1a can receive positioning signals from artificial satellites and measure the current position of the seedling transplanter. The IMU SN1b can measure acceleration and angular velocity and measure the direction (traveling direction) and attitude (left-right inclination and front-back inclination) of the seedling transplanter. Therefore, by correcting the measurement result of the GNSS receiver SN1a with the IMU SN1b, it is possible to measure the current position with higher accuracy compared to the case of measuring the current position only by the GNSS method.

[0040] The planting switch SW1 is operated for an input operation of "planting start" to operate the seedling planter 41 or "planting stop" to stop the seedling planter 41. The hydraulic sensitivity switch SW2, which is an example of a sensitivity adjuster, sets the sensitivity of the rise and fall (strictly speaking, the inclination around the axis) of the float 6. The float 6 has a function of contacting the field and leveling the field surface. When the field is hard, if the float 6 rises and falls easily, the leveling of the field is likely to be insufficient. When the field is soft, if the float 6 is difficult to rise and fall, the float 6 is likely to sink into the soft soil. Also, the float 6 rises and falls (rotates around the support axis) according to the unevenness of the field. When the float 6 rises and falls, the seedling planting device 3 is also raised and lowered by the lift cylinder so that the planting depth becomes constant. When the hydraulic sensitivity switch SW2 is operated to make the sensitivity (ease of rising and falling) of the float 6 sensitive, the float 6 easily rises and falls even with small unevenness, and the seedling planting device 3 is likely to move up and down erratically. Therefore, in a hard field, a field with many unevennesses, or a rough field, the sensitivity is often set to the insensitive side by operating the hydraulic sensitivity switch SW2. The float angle sensor SN2 detects the inclination angle of the float 6. The straight-ahead assist start switch SW3 inputs to start the straight-ahead assist operation that makes the transplanter travel straight automatically while planting seedlings.

[0041] The control unit 300 transmits control signals to the engine 12, the steering handle 16, the HST, the planting clutch of the seedling planting device 3, the rotor lifting device, the fertilizer application device 4, the lift cylinder, etc., which are examples of controlled elements, to control the raising and lowering, operation / stop of the seedling planting device 3, the height of the leveling rotor 21, the operation / stop of the fertilizer application device, and the speed change of the HST (Hydraulic Static Transmission), which is an example of a speed change device. Note that the HST is a conventionally known commercially available speed change device that steplessly adjusts the inclination angle of the internal swash plate by rotating the trunnion shaft to change the power from the engine 12. Also, the control unit 300 outputs control signals to a liquid crystal monitor or a high-mount monitor, which are examples of a display unit, to be able to display work information and work status.

[0042] The positioning means 301 measures the current position of the seedling transplanter based on the measurement results of the positioning device SN1. The low-speed switch input discrimination means 302 discriminates whether any input of the forward position, neutral position, or reverse position is being input to the low-speed switch 63 based on the input of the low-speed switch 63. The hydraulic sensitivity detection means 303 detects the hydraulic sensitivity based on the input of the hydraulic sensitivity switch SW2.

[0043] The float angle detection means 304 detects the angle of the float 6, that is, the height of the float 6 and the unevenness of the field, based on the detection results of the float angle sensor SN2. The inclination detection means 305 detects the inclination of the traveling vehicle 1 based on the detection results of the IMU SN1b.

[0044] The HST control means 306 controls the HST based on the operation position of the HST lever 33 to control the traveling speed. The HST control means 306 in the embodiment controls the opening degree of the trunion shaft of the HST to control the gear ratio steplessly. Also, the HST control means 306 in the embodiment changes the gear ratio by controlling the opening degree of the trunion shaft and controls forward and reverse by switching the positive and negative with respect to the neutral angle of the inclination angle of the swash plate interlocked with the trunion shaft. Note that the control of the trunion shaft can be performed using an actuator or a trunion motor. The HST control means 306 in the embodiment controls the upper limit of the opening degree of the trunion shaft when the low-speed switch 63 is input to the forward position or the reverse position. Specifically, the upper limit of the opening degree of the trunion shaft is limited to a limit opening degree (limit value) corresponding to the forward limit speed or the reverse limit speed. The limit opening degree is set to a lower value compared to the reference opening degree (reference value) without speed limitation during road travel or the like. In a state where the upper limit of the opening degree of the trunion shaft is limited to the limit opening degree (low-speed travel standby state), the traveling vehicle 1 does not travel, and when the travel lever 62 is operated (grasped) in the low-speed travel standby state, the traveling vehicle 1 travels within the limit speed according to the operation state. That is, in the low-speed travel standby state, even if the travel lever 62 is grasped, the vehicle does not travel at a speed exceeding the limit speed.

[0045] Note that when the HST control means 306 of the embodiment is in a state where the HST lever 33 is operated to the neutral position, the traveling vehicle 1 has stopped traveling, and the planting switch SW1 is set to "planting off" and the seedling planting tool 41 has stopped, and the micro speed switch 63 is operated to the forward position or the reverse position, it shifts to the micro speed traveling standby state. Therefore, when the HST lever 33 operated from the driver's seat 20 side is not operated to the neutral position, or when the traveling vehicle 1 has not stopped during the execution of the straight-ahead assist or the like, or when the seedling planting tool 41 is operating, even if the micro speed switch 63 is operated, it does not shift to the micro speed traveling standby state. This is to prevent the traveling vehicle 1 from being suddenly controlled to a very low speed and suddenly braked during traveling even if the micro speed switch 63 accidentally reacts due to flying stones, splashed mud, etc. during the planting operation or traveling. Therefore, it is possible to prevent the operator in the driver's seat 20 from being injured by sudden braking and the seedling planting from being disturbed.

[0046] Further, when the traveling lever 62 is operated in the micro speed standby state, the HST control means 306 of the embodiment causes the traveling vehicle 1 to travel within the range of the restricted speed, and during the traveling within the range of the restricted speed, after the tilt angle in the longitudinal direction of the traveling vehicle 1 measured by the tilt detection means 305 reaches a predetermined first angle (for example, 5°), when the tilt angle in the longitudinal direction of the traveling vehicle 1 no longer reaches the first angle, the control that restricts the upper limit of the opening degree of the trunnion shaft to the limit value is released. That is, when returning after exceeding the first angle during traveling in the micro speed standby state, the HST control means 306 determines that it has crossed a convex portion such as a ridge or a slope for loading and unloading on a truck, and releases the micro speed standby state. Therefore, in a situation where it is highly likely that it has crossed a ridge or the like and has become a flat state where it is possible to travel at a normal speed, the state where the traveling speed is automatically restricted is released. That is, the micro speed standby state is automatically released without performing an operation to release the micro speed standby state, and it becomes possible to travel at a normal speed. If continuous traveling at a very low speed is still required, the micro speed switch 63 may be operated again.

[0047] Furthermore, when the planting switch SW1 is operated to "planting in" or the grounding of the float 6, i.e., the lowering of the seedling planting device 3, is detected by the float angle detecting means 304 in the very slow standby state, the HST control means 306 of the embodiment determines that the seedling planting device 3 has become in a state where work can be started, and performs control to limit the upper limit of the opening degree of the trunnion shaft to a limit value, that is, releases the very slow standby state. When the work can be started and the very slow traveling becomes unnecessary, the very slow standby state is automatically released, and the workability is improved compared to the case of manually releasing the very slow standby state. For example, in a field where a turning slope for turning, so-called turning farm road, is formed at the outer edge of the field, after traveling at a very slow speed on the turning farm road and then entering the field and lowering the seedling planting device 3, the very slow standby state is automatically released, and the workability is improved compared to the case of manually releasing the very slow standby state. Note that the lowering of the seedling planting device 3 can also be detected by a sensor provided in the lifting link device 2.

[0048] The traveling control means 307 controls the traveling of the seedling transplanter by controlling the engine 12 and the steering wheel 16. The traveling control means 307 of the embodiment controls the rotation speed of the engine 12 or controls the HST via the HST control means 306 according to the operations of the operator such as the steering wheel 16, the accelerator pedal, the brake pedal, and the HST lever 33 during manual traveling, to make the seedling transplanter travel. Also, when the input of the straight-ahead assist start switch SW3 is received, based on the current position measured by the positioning device SN1 and the traveling direction, the rotation speed of the engine 12 and the steering control of the steering wheel 16 are performed so as to travel straight automatically.

[0049] The work implement control means 308 controls the seedling planting device 3 as an example of a work implement. The work implement control means 308 of the embodiment controls the lifting cylinder and the planting clutch to control the raising and lowering and the operation / stop of the seedling planting device 3.

[0050] The rotor height control means 309 controls the rotor lifting device to control the height of the land leveling rotor 21. When the rotor height control means 309 in the embodiment adjusts the sensitivity of the float 6 to the sensitive side with the hydraulic pressure sensitivity switch SW2, the height of the land leveling rotor 21 is made lower than when adjusted to the insensitive side. However, when the hydraulic pressure sensitivity switch SW2 is set to the sensitive side (soft side) with respect to the reference setting, it becomes easy to slide on the soil surface and float during traveling, and the seedling planting device 3 tends to float. Therefore, the height of the land leveling rotor 21 also tends to increase. Conversely, when set to the insensitive side (hard side), it becomes easy to push the soil surface during traveling, and the seedling planting device 3 tends to sink. Therefore, the height of the land leveling rotor 21 also tends to decrease. Thus, when the setting of the hydraulic pressure sensitivity switch SW2 is changed, the height of the land leveling rotor 21 tends to fluctuate and the height of the land leveling rotor 21 becomes unstable. Conventionally, even when the hydraulic pressure sensitivity was changed, the height of the land leveling rotor 21 was not changed. In the rotor height control means 309 of the embodiment, when the setting of the hydraulic pressure sensitivity switch SW2 is changed to the sensitive side (soft side), the height of the land leveling rotor 21 is lowered, and when the setting of the hydraulic pressure sensitivity switch SW2 is changed to the insensitive side (hard side), the height of the land leveling rotor 21 is raised, and control is performed so that the height of the land leveling rotor 21 is stabilized.

[0051] In addition, when the hydraulic pressure sensitivity switch SW2 is operated to change the sensitivity to the sensitive side while the float 6 is in contact with the ground, it is preferable not to lower the land leveling rotor 21. When the land leveling rotor 21 is lowered in a state where the float 6 is in contact with the ground, that is, in a state where the seedling planting device 3 has descended, the operation of sinking the land leveling rotor 21 into the soil is performed, and loads are applied to each part of the land leveling rotor 21 and the seedling planting device 3, and there is a risk of damage. Therefore, in this case, it is preferable not to lower the land leveling rotor 21. When the hydraulic pressure sensitivity switch SW2 is operated to the sensitive side while the float 6 is in contact with the ground, it is desirable to display on the high mount monitor or the like to prompt the raising of the seedling planting device 3. Also, when the hydraulic pressure sensitivity switch SW2 is operated, it is also preferable to display the height of the land leveling rotor 21 on the high mount monitor.

[0052] Also, the reference height of the land preparation rotor 21 can be fixed at the time of factory shipment or the like, but is not limited to this. It is also possible for the operator to manually set and change it, or to make changes such as setting the height of the land preparation rotor 21 at the start of the seedling transplanter as the reference height. Since there may be a deviation over time between the actual height of the land preparation rotor 21 and the set value of the hydraulic sensitivity switch SW2, it is better to change it in a timely manner, such as at the start of the seedling transplanter, rather than fixing it, so that damage when lowering the land preparation rotor 21 is more easily suppressed. Furthermore, the rotor lifting device can adopt any configuration, and it is possible to use a motor or a hydraulic cylinder. Also, in the embodiment, an aspect of changing the height of the land preparation rotor 21 according to the setting of the hydraulic sensitivity switch SW2 is exemplified, but it is not limited to this. For example, in addition to the setting of the hydraulic sensitivity switch SW2, since the float 6 is more likely to float as the traveling speed increases, it is also possible to change the height of the land preparation rotor 21 according to the traveling speed.

[0053] In the seedling transplanter of the embodiment having the above configuration, when the traveling lever 62 is operated with the micro speed switch 63 provided on the over-ridge handle 61 in front of the traveling vehicle 1 in the forward position or the reverse position, the traveling vehicle 1 travels at a micro speed. Therefore, compared with the conventional technology that requires the operation of stepping on the shift pedal while sitting, accidents such as tripping and falling are suppressed, and the operation of traveling at a micro speed is easy. Also, by operating the traveling lever 62, it is possible to travel with the traveling speed limited to a micro speed, and it is possible to easily adjust the vehicle speed at low speeds, which is difficult with lever operations such as the HST lever.

[0054] In FIG. 4, as an example, the control unit 300 of the embodiment has the positioning means 301 to the inclination detection means 305 unitized as the main ECU (Electronic Control Unit) 401, the HST control means 306 is the HST ECU 402, the traveling control means 307 is the traveling ECU 403, and the work implement control means 308 and the rotor height control means 309 are unitized as the work implement ECU 404. Each of the ECUs 401 to 404 can communicate with each other via signal lines and is powered by the battery 406.

[0055] FIG. 5 is an explanatory diagram of the engine stop control circuit of the control unit of the embodiment. FIG. 5(A) is an explanatory diagram of a conventional configuration, and FIG. 5(B) is an explanatory diagram of the configuration of the engine stop control circuit of the embodiment. In FIG. 5(A), in the conventional engine stop control circuit, the contact portion 04a of the fuse cut relay switch 04 is connected in series to the key stop solenoid 02 for stopping the engine via the power supply path 03 interlocked with the key operation, and the coil portion 04b of the fuse cut relay switch 04 is connected in parallel to the contact portion 04a. The fuse cut relay switch 04 in FIG. 5(A) is composed of a normally open (NO) type relay switch. Further, the contact portion 06a of the short relay switch 06 is connected in series to the coil portion 04b of the fuse cut relay switch 04. Also, the coil portion 06b of the short relay switch 06 is arranged in parallel to the contact portion 06a of the short relay switch 06, and the coil portion 06b is connected in series to the main ECU 01. The short relay switch 06 in FIG. 5(A) is composed of a normally closed (NC) type relay switch.

[0056] Therefore, in the conventional circuit shown in FIG. 5(A), normally, the coil portion 06b of the short relay switch 06 is not energized and the contact portion 06a is closed. Therefore, the coil portion 04b of the fuse cut relay switch 04 is in an energized state and the contact portion 04a is closed. Thus, the key stop solenoid 02 is turned on and the engine is kept in an operating state. When the fuse blows due to overcurrent or the like and is heated, the coil portion 04b of the fuse-blow relay switch 04 is no longer energized. When the coil portion 04b is de-energized, the contact portion 04a opens, the key stop solenoid 02 turns off, and the engine stops. Also, when the output 01a of the main ECU 01 turns on, that is, when a signal to stop the engine is output from the main ECU 01 (when 12V is supplied), the coil portion 06b of the short relay switch 06 is energized and the contact portion 06a opens. Therefore, the coil portion 04b of the fuse-blow relay switch 04 is no longer energized, the key stop solenoid 02 turns off, and the engine stops.

[0057] In the conventional configuration shown in FIG. 5(A), when the main ECU 01 itself fails and cannot output a signal to stop the engine, there is a problem that the engine cannot be stopped. In FIG. 5(B), the control unit 300 of the embodiment has a key stop solenoid 412, a power supply path 413, a fuse-blow relay switch 414, and a short relay switch 416 similar to the conventional key stop solenoid 02, power supply path 03, fuse-blow relay switch 04, and short relay switch 06. A diode 417 is connected in series between the main ECU 401 and the coil portion 416b of the short relay switch 416.

[0058] Also, the traveling ECU 403 of the embodiment is also connected to the power supply path 413. The coil portion 421b of the first engine stop relay switch 421 is connected in series to the first connection path 413a that connects the first output 403a of the traveling ECU 403 and the power supply path 413. Further, the coil portion 422b of the second engine stop relay switch 422 is connected in series to the second connection path 413b that connects the second output 403b of the traveling ECU 403 and the power supply path 413.

[0059] A third connection path 413c that connects in parallel with the contact part 414a and the coil part 414b of the fuse cut-off relay switch 414, and the node 417a between the coil part 416b of the short circuit relay switch 416 and the diode 417 is connected to the power supply path 413. In the third connection path 413c, the contact part 421a of the first engine stop release switch 421 and the contact part 422a of the second engine stop release switch 422 are connected in series. The engine stop release switches 421 and 422 of the embodiment are both composed of normally open (NO) type relay switches.

[0060] In the configuration of the embodiment shown in FIG. 5(B), during normal operation, when the fuse is blown, or when a signal for engine stop is output from the main ECU 401, it operates in the same manner. During normal operation, the two outputs 403a and 403b of the travel ECU 403 are off, the coil parts 421b and 422b of the two engine stop release switches 421 and 422 are non-energized, and the contact parts 421a and 422a are in an open state. When an instruction to stop the engine is given from the travel ECU 403, the two outputs 403a and 403b turn on, and the coil parts 421b and 422b are in an energized state. Therefore, the contact parts 421a and 422a close, and the coil part 416b of the short circuit relay switch 416 is energized. Therefore, the contact part 416a of the short circuit relay switch 416 opens, the coil part 414b of the fuse cut-off relay switch 414 is non-energized, the contact part 414a opens, the key stop solenoid 412 turns off, and the engine stops.

[0061] Therefore, in the embodiment shown in FIG. 5(B), even when the main ECU 401 fails and cannot output an engine stop signal, the engine can be stopped by a signal from the travel ECU 403. Therefore, safety is improved. Note that when the contact parts 421a and 422a of the engine stop release switches 421 and 422 turn on, the main ECU 401 is protected by the diode 417 so that current does not flow from the battery 406 side to the main ECU 401 side.

[0062] In the embodiment, even if only one of the two outputs 403a, 403b of the travel ECU 403 is turned on, the third connection path 413c is not energized, so the engine does not stop, but if both are turned on, the engine stops. Therefore, even if all the output terminals of the existing travel ECU 403 are already in use, two of the terminals in use can be used as the outputs 403a, 403b for stopping the engine, without the need to add an output terminal for stopping the engine. In other words, even if the existing travel ECU 403 does not have a vacant output, the engine stop control can be added. If the traveling ECU 403 has an available output, it is possible to use one output and perform engine stop control with one engine stop relay switch. It is also possible to configure the engine stop control to be performed using three or more outputs and three or more engine stop relay switches.

[0063] FIG. 6 is an explanatory diagram of a lateral feed speed change lever portion for changing the number of lateral feeds of the seedling tank according to the embodiment, as viewed from the rear of the machine body. FIG. 7 is an explanatory diagram of a lateral feed speed change lever portion for changing the number of lateral feeds of the seedling tank according to the embodiment, as viewed from the front of the machine body. FIG. 8 is an explanatory diagram of a lateral feed speed change lever portion for changing the number of lateral feeds of the seedling tank according to the embodiment, and is a perspective view seen obliquely from the front. 6 to 8, in the seedling transplanter of the embodiment, in order to pick up seedlings evenly from the mat seedlings with the planting claws when planting seedlings, similar to the conventional seedling transplanting stage, the seedling tank 39 is configured to be able to move back and forth in the left and right direction (lateral direction, width direction of the traveling vehicle 1). It is also known that by increasing or decreasing the number of times the seedling tank 39 is lateral fed per unit time (number of times it reciprocates in the left and right direction), the number of times the planting claws pick up seedlings increases or decreases in tandem, and the interval between seedlings planted in the field can be narrowed or widened. The number of times the seedlings are lateral fed can be changed by a speed change device that changes the output of the lateral feed motor, and the speed change ratio is adjusted by operating the lateral feed speed change lever 501 (an example of a number change tool).

[0064] In the conventional configuration, the lateral feed speed change lever 501 is a manually operated member, whereas in the embodiment, it can be manually operated and is also configured to be automatically adjustable. In the lateral feed speed change lever 501 of the embodiment shown in FIGS. 6 to 8, as an example of the driven part, a protrusion 502 extending forward is formed. The protrusion 502 penetrates a long hole 503a formed in a sector gear 503 as an example of the interlocking part. The sector gear 503 is rotatable about a rotation shaft 503b at the upper end. The rotation position of the sector gear 503 is adjusted by the drive of a motor 504 (an example of a drive device) disposed on the front side of the lateral feed speed change lever 501. An angle sensor 506 as an example of an interlocking position detection member is supported on the rotation shaft 503b, and the angle sensor 506 detects the rotation angle of the rotation shaft 503b.

[0065] Therefore, in response to the input of a switch on a steering board (not shown), by rotating the motor 504 forward and backward while detecting the rotation angle with the angle sensor 506, the rotation position of the sector gear 503 can be controlled, and the lateral feed speed change lever 501 interlocked with the sector gear 503 and the protrusion 502 can be moved to adjust the number of lateral feeds. Even when the lateral feed speed change lever 501 is manually operated, it is also possible to obtain the current setting of the number of lateral feeds from the detection result of the angle sensor 506. In the conventional configuration, the lateral feed speed change lever 501 is disposed near the center of the machine body on the back side (front side) of the seedling tank, and is disposed at a position where it is difficult to operate the lateral feed speed change lever 501. In the embodiment, although the lateral feed speed change lever 501 can be manually operated, the number of lateral feeds can be automatically adjusted via the motor 504, improving workability.

[0066] (Modification example) The work vehicle of the present invention is not limited to a seedling transplanter, and can also be applied to various work vehicles capable of fertilizing and spraying chemicals, such as tractors and chemical liquid spraying vehicles. In addition, although an example of the work vehicle has been shown as a configuration in which an operator rides and performs operations, it is not limited to this. It is also applicable when a self-driving work vehicle that does not have an operator on board, so-called a work robot, crosses a ridge after the work is completed, or is stored in a truck or a storage shed.

Explanation of Signs

[0067] 1…Vehicle body, 3…Work implement, seedling planting device, 6…Float, 12…Engine, 21…Soil tilling rotor, 31…Hydraulic continuously variable transmission, HST, 36…Lifting device, 39…Seedling tank, 41…Seedling planting tool, 62…Operating tool, 63…Changing tool, 300…Control unit, 501…Rotation number changing tool, 502…Driven part, 503…Linking part, 504…Driving device, 506…Linking position detecting member, SN1b…Inclination measuring member, SW2…Sensitivity adjusting tool.

Claims

1. An engine (12) mounted on a vehicle body (1), a hydraulic continuously variable transmission that changes the power from the engine (12) by adjusting the opening degree of a trunnion shaft, an operating tool (62) for performing an operation of adjusting the opening degree of the trunnion shaft, a changer (63) for performing an operation of changing the upper limit of the opening degree of the trunnion shaft, a control unit (300) for controlling the upper limit of the opening degree of the trunnion shaft based on the operating state of the changer (63), A work vehicle characterized by comprising the above.

2. A working machine (3) provided on the vehicle body (1) for performing work in a field, When an operation to stop the running of the vehicle body (1) is performed, and the vehicle body (1) has stopped running, and the working machine (3) has stopped, and the changer (63) performs an operation of restricting the upper limit of the opening degree of the trunnion shaft to a limit value lower than a predetermined reference value, the control unit (300) for controlling the opening degree of the trunnion shaft to the limit value, The work vehicle according to claim 1, characterized by comprising the above.

3. An inclination measuring member (SN1b) for measuring the inclination of the vehicle body (1), When the operating tool (62) is operated in a state where the opening degree of the trunnion shaft is controlled to a limit value lower than a predetermined reference value, the vehicle body (1) is caused to run within the range of the limit value, and during running within the range of the limit value, after the inclination angle in the front-rear direction of the vehicle body (1) reaches a predetermined first angle, when the inclination angle in the front-rear direction of the vehicle body (1) no longer reaches the first angle, the control unit (300) for canceling the control of restricting the upper limit of the opening degree of the trunnion shaft to the limit value, The work vehicle according to claim 1, characterized by comprising the above.

4. The control unit (300) for canceling the control of restricting the upper limit of the opening degree of the trunnion shaft to a limit value lower than a predetermined reference value when the working machine (3) becomes in a state where work can be started, The work vehicle according to claim 1, characterized by comprising the above.

5. The operating tool (62) capable of adjusting the opening degree of the trunnion shaft from the outside of the vehicle body (1) in a state where the vehicle body (1) is not occupied, The changer (63) disposed near the operating tool (62), which is operable between a forward position for restricting the opening degree upper limit of the trunnion shaft when the vehicle body (1) is moving forward to a limit value lower than a predetermined reference value, a reverse position for restricting the opening degree upper limit of the trunnion shaft when the vehicle body (1) is moving backward to the limit value, and a neutral position for stopping the vehicle body (1), and the changer (63) that automatically returns to the neutral position when the hand leaves the changer (63) during operation at the forward position or the reverse position. The work vehicle according to claim 1, characterized by comprising the above.

6. A working machine (3) composed of a seedling planting device (3) having a seedling tank (39) for accommodating seedlings and a seedling planting tool (41) for planting seedlings in a field. A frequency changer (501) for changing the number of times of reciprocating movement of the seedling tank (39) in the width direction of the vehicle body (1). An interlocking part (503) movable in conjunction with an interlocked part (502) provided on the frequency changer (501). An interlocking position detection member (506) for detecting the position of the interlocking part (503). A drive device (504) for changing the number of reciprocating movements by moving the frequency changer (501) by moving the interlocking part (503) according to the number of reciprocating movements. The work vehicle according to claim 1, characterized by comprising the above.

7. A working machine (3) composed of a seedling planting device (3) having a seedling tank (39) for accommodating seedlings, a seedling planting tool (41) for planting seedlings in a field, a leveling rotor (21) for leveling the field in contact with the field, and a float (6) for leveling the field in contact with the field. A lifting device (36) for lifting and lowering the working machine (3) based on the variation of the float (6) in contact with the field. A sensitivity adjuster (SW2) for adjusting the sensitivity of the variation of the float (6). A control unit (300) for lowering the height of the leveling rotor (21) when the sensitivity is adjusted to the sensitive side by the sensitivity adjuster (SW2) compared to when it is adjusted to the insensitive side. The work vehicle according to claim 1, characterized by comprising the above.

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