Work vehicle

Abstract

This work vehicle is provided with: an engine provided on a traveling vehicle body; a hydraulic continuously variable transmission for shifting and outputting the power input from the engine; and a setting tool which is an operation tool capable of adjusting a vehicle speed of the traveling vehicle body by adjusting a trunnion opening of the hydraulic continuously variable transmission, adjusts the trunnion opening by using the operation tool, within a range up to a set trunnion opening, and receives a change operation for the set trunnion opening. The engine rotation speed is linked to a position of the operation tool regardless of the operation on the setting tool. Thus, the work vehicle which improves the safety of workers can be provided.

Description

Work vehicles

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

[0002] BACKGROUND ART Conventionally, there is known a work vehicle in which the vehicle speed of the traveling vehicle body is set in accordance with the depression amount of a speed change pedal provided on the traveling vehicle body, and the traveling vehicle body is caused to travel (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2000-236714

[0004] For example, when loading or unloading a work vehicle onto or from a truck, or when moving a work vehicle on a slope, such as when entering or leaving a field, fine adjustment of operating tools such as a gear change pedal is required.

[0005] However, with the above technology, it can be difficult to fine-tune operating tools such as a gear change pedal when moving on an inclined surface due to tilting or vibration of the traveling vehicle body, which can cause the traveling vehicle body to move in an unexpected way when moving on an inclined surface, leaving room for improvement in terms of worker safety.

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

[0007] In order to solve the above-mentioned problems and achieve the object, a work vehicle (1) according to one aspect of the embodiment comprises an engine (30) provided on a traveling body (2), a hydraulic continuously variable transmission (14) that changes the speed of the power input from the engine (30) and outputs it, and an operating device (36) that can adjust the vehicle speed of the traveling body (2) by adjusting the trunnion opening of the hydraulic continuously variable transmission (14), and is equipped with a setting device (49) that adjusts the trunnion opening within a range up to a set trunnion opening using the operating device (36) and accepts operation to change the set trunnion opening, and the engine (30) rotation speed is linked to the position of the operating device (36) regardless of operation of the setting device (49). The invention of claim 2 is the work vehicle according to claim 1, characterized in that it has a first vehicle speed mode and a second vehicle speed mode that are set in response to operation of the setting device (49), the second vehicle speed mode being a mode in which the set upper limit of the trunnion opening is smaller than that of the first vehicle speed mode, and in the second vehicle speed mode, the set trunnion opening is reached midway through the operation range of the operating device (36).The invention of claim 3 is the work vehicle according to claim 2, characterized in that after the set trunnion opening is reached, by further operating the operating device (36) to the speed-up side, the engine speed increases while the trunnion opening remains constant at the set trunnion opening.The invention of claim 4 is the work vehicle according to claim 2 or 3, characterized in that the second vehicle speed mode is released on the condition that the operating device (36) is in the neutral position and the setting device (49) is set to a mode other than the second vehicle speed mode.

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

[0009] Fig. 9 is a side view showing a work vehicle. Fig. 9 is a plan view showing a work vehicle. Fig. 9 is an explanatory diagram of an HST. Fig. 9 is an explanatory diagram of a lever guide unit. Fig. 9 is an explanatory diagram of a setting switch. Fig. 9 is a block diagram showing a control system centered on the control device of the seedling transplanter. Fig. 9 is a diagram showing the relationship between the position of the main speed change operation lever, the trunnion opening, and the engine rotation speed. Fig. 9 is a flowchart showing the upper limit opening setting process for the trunnion opening according to the embodiment. Fig. 9 is an explanatory diagram of a ridge crossing handle according to the embodiment, where Fig. 9(A) is an overall explanatory diagram of the ridge crossing handle and Fig. 9(B) is an enlarged view of the slow speed switch.

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

[0011] In the following description, the forward / rearward direction refers to the direction of travel of the work vehicle (1) when traveling straight, with the front side of the traveling direction being defined as "front" and the rear side being defined as "rear." The traveling direction of the work vehicle (1) is the direction from the driver's seat (41) toward the handle (35) (steering device) when traveling straight (see Figures 1 and 2).

[0012] In this embodiment, the work vehicle (1) is described as a riding seedling transplanter (1) that has a seedling planting unit (4) as a work device and that plants seedlings in a field. As shown in Figures 1 and 2, the seedling transplanter (1) has a seedling planting unit (4) that can be raised and lowered via a lifting link mechanism (3) on the rear side of a traveling vehicle body (2) to plant seedlings in a field.

[0013] The main body of the fertilizer applicator (5) is disposed on the upper rear side of the traveling body (2). If the work vehicle (1) is not a seedling transplanter (1), it may be provided with a seed sowing device or the like as a work device.

[0014] The traveling body (2) is a four-wheel drive vehicle equipped with left and right front wheels (10) and rear wheels (11) which are drive wheels. A transmission case (13) for transmitting driving force to the seedling planting section (4) and the like, and a hydraulic continuously variable transmission (14) for outputting driving force supplied from the engine (30), i.e., rotation generated by the engine (30), to the transmission case (13) are provided in front of a main frame (15) which constitutes the body skeleton of the traveling body (2).

[0015] The continuously variable transmission 14 is a hydrostatic continuously variable transmission known as an HST (Hydro Static Transmission). In the following, a case where the continuously variable transmission is an HST 14 will be described.

[0016] The HST (14) will now be described with reference to Fig. 3. Fig. 3 is an explanatory diagram of the HST (14).

[0017] As shown in Figure 3, the HST (14) uses power from the engine (30) to drive a hydraulic pump (141) to generate hydraulic pressure, and then converts this hydraulic pressure into mechanical power (rotational power) using a hydraulic motor (142) to output it. At this time, by operating a main transmission operation lever (36) described later, the rotation angle (hereinafter referred to as "trunnion opening") of a trunnion shaft (147) of the HST (14) is changed via a trunnion shaft actuator such as an HST motor (146), thereby changing the tilt angle of a swash plate (148), thereby making it possible to change the output of the HST (14) in a stepless manner.

[0018] That is, pressure oil corresponding to the tilt angle of the swash plate (148) is supplied from the hydraulic closed circuit (143) to the hydraulic motor (142), and this hydraulic motor (142) drives the output shaft (145), thereby changing the rotational speed of the front wheels (10) and rear wheels (11). In this way, the HST (14) converts the power generated by the engine (30) into power for propelling the traveling vehicle body (2), and by changing the output and output direction, it is possible to control the forward / reverse movement and traveling speed (vehicle speed) of the traveling vehicle body (2). In FIG. 3, reference numeral (80) denotes 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.

[0019] 1 and 2, an auxiliary transmission mechanism (16) is provided within the transmission case (13) for switching the driving mode of the traveling vehicle body (2) between high-speed mode for road driving and low-speed mode for planting seedlings. That is, the auxiliary transmission mechanism (16) switches between a high-speed mode for road speed and a low-speed mode for planting seedlings. 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 protrude outward from front wheel support parts that can change the steering direction of the left and right front wheel final cases (10a).

[0020] An engine (30) is mounted on the main frame (15). Rotational power of the engine (30) is transmitted to the transmission case (13) via the belt transmission device (21) and the HST (14). The rotational power transmitted to the transmission case (13) is changed in speed by the sub-transmission mechanism (16) in the transmission case (13), and then separated into running power and externally extracted power.

[0021] The rotational power of the engine (30) is transmitted to a hydraulic pump, and the hydraulic pressure generated by the hydraulic pump is supplied to the HST (14), a power steering mechanism (not shown) of the handle (35), the lift cylinder (25), etc.

[0022] The externally extracted power extracted from the rotational power transmitted to the transmission case (13) is transmitted to a planting clutch case (27) provided at the rear of the running body (2), and is transmitted from the planting clutch case (27) to the seedling planting section (4) by a planting transmission shaft (67).

[0023] Meanwhile, left and right drive shafts (42) are provided at the rear of the transmission case (13). 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).

[0024] In addition, a side clutch (not shown) for turning on and off the power transmission to the left and right drive shafts 42 is disposed upstream of the left and right drive shafts 42 in the power transmission direction. As shown in Figure 1, a side clutch pedal 43a for turning on and off the left and right side clutches is provided at the front lower part of the cockpit 41 and on one of the left and right sides.

[0025] When the side clutch pedal (43a) on the inside of the turning is depressed out of the left and right side clutch pedals (43a) to put the side clutch in a disengaged state and then the steering wheel (35) is operated to turn, the driving rotation of the rear wheel (11) on the inside of the turning can be completely cut off.

[0026] A bonnet (39) with a control panel (38) for operating each part is provided on the upper front part of the vehicle body (2). The control panel (38) is provided with a monitor (not shown) and the like.

[0027] The hood (39) is also provided with a handle (35) for steering the running body (2), a main speed change operation lever (36) for operating the HST (14) and the seedling planting section (4), and an auxiliary speed change operation lever (37) for operating the auxiliary speed change mechanism (16).

[0028] The main speed change control lever (36) is an operating tool (first operating tool) that can adjust the speed of the traveling vehicle body (2) by adjusting the opening of the trunnion shaft (147) of the HST (14). The main speed change control lever (36) is operated, for example, by a driver. The main speed change control lever (36) accepts speed change operations by the driver.

[0029] The main transmission operation lever (36) is provided so as to be movable along a lever guide portion (815), for example, as shown in Figure 4. Figure 4 is a diagram illustrating the lever guide portion (815). As shown in Figure 4, the lever guide portion (815) is largely divided into a forward travel area (811) on the front side of the vehicle body, a reverse travel area (813) on the rear side of the vehicle body, and a neutral area (812) located so as to be sandwiched between them. Note that the lever guide portion (815) in Figure 4 is merely an example and is not limited to this.

[0030] When the main speed change lever (36) is positioned in the forward travel area (811), the seedling transplanter (1) moves forward, and the closer it is to the front, the faster it moves. When the main speed change lever (36) is positioned in the reverse travel area (813), the seedling transplanter (1) moves backward, and the closer it is to the rear, the faster it moves.

[0031] That is, the main speed change control lever (36) is provided so that its position can be changed across a forward travel region (811) and a reverse travel region (813) across a neutral region (812), and the output of the HST (14) can be adjusted depending on the operation position. That is, the tilt angle of the swash plate (148) of the HST (14) changes depending on the amount of operation of the main speed change control lever (36) within the lever guide portion (815), and the output from the HST (14), i.e., the travel speed, is changed continuously.

[0032] The rotation speed of the engine (30) is set by the amount of operation of the main transmission control lever (36). For example, when the main transmission control lever (36) is positioned in the forward driving region (811), the rotation speed of the engine (30) increases as the main transmission control lever (36) approaches the frontmost position.

[0033] On the other hand, when the main speed change lever (36) is placed in the neutral region (812), the output from the HST (14) is stopped and the seedling transplanter (1) stops. Furthermore, in the seedling transplanter (1), the brakes are forcibly applied to the front wheels (10) and rear wheels (11).

[0034] When the driver stops operating the main speed change operation lever (36), the lever is held in the position where the driver stopped operating it.

[0035] As shown in FIG. 5, the hood (39) is provided with a setting switch (49) (setting tool) that can change and set the upper limit of the trunnion opening of the HST (14). FIG. 5 is a diagram illustrating the setting switch (49). The setting switch (49) is, for example, a switch that is provided so as to be rotatable in the vertical direction. The setting switch (49) can be rotated by the operator. The setting switch (49) accepts the operator's operation to set the upper limit of the opening. The setting switch (49) is a switch for setting the upper limit of the trunnion opening when the traveling vehicle body (2) is moving forward and when moving backward. The setting switch (49) may be a button type or the like.

[0036] When the setting switch (49) is in the first position (upper position), for example, the vehicle speed mode is set to the first vehicle speed mode. In the first vehicle speed mode, the upper limit of the trunnion opening is set to the first upper limit. The first upper limit is the normal upper limit and is set according to the position of the main transmission operation lever (36).

[0037] When the setting switch (49) is, for example, in the second, lower position, the vehicle speed mode is set to the second vehicle speed mode. In the second vehicle speed mode, the upper limit of the trunnion opening is set to a second upper limit. The second upper limit is smaller than the first upper limit. In other words, the second vehicle speed mode is a mode in which the speed of the traveling vehicle body (2) is slower than in the first vehicle speed mode.

[0038] 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 when it is moving backward. For example, in the second vehicle speed mode, the second upper limit opening degree when moving backward is smaller than the second upper limit opening degree when moving forward.

[0039] 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 when reversing is about 30% of the vehicle speed in the first vehicle speed mode when reversing.

[0040] The trunnion opening here is the opening relative to the state in which the swash plate (148) (see FIG. 3) is not tilted. The trunnion openings in forward and reverse travel are, for example, amounts of change relative to the state in which the swash plate (148) is not tilted, and both will be described as positive values. The setting switch (49) may be provided separately for forward travel and reverse travel.

[0041] An accelerator pedal (110) (second operating tool) that can be depressed by the driver 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. Specifically, when the driver is not depressing the accelerator pedal (110), the accelerator pedal (110) is biased by the biasing means to return to the initial position. When the driver depresses the accelerator pedal (110), the accelerator pedal (110) rotates from the initial position in accordance with the driver's depressing force. When the driver no longer depresses the accelerator pedal (110), the accelerator pedal (110) returns to the initial position by the biasing force of the biasing means.

[0042] The controller (100) is connected to actuators such as a throttle motor (not shown), hydraulic control valves (81, 82), a planting clutch actuation solenoid (83), a side clutch actuation solenoid (84), an HST motor (146), a line drawing marker lifting motor (87), a steering motor (95), and a differential lock switching motor (96).

[0043] The throttle motor increases or decreases the rotation speed of the output shaft (30a) of the engine (30) by operating a throttle that adjusts the amount of intake air of the engine (30).

[0044] The HST motor (146) changes the inclination angle of the swash plate (148) of the HST (14) by changing the trunnion opening degree of the HST (14).

[0045] The controller (100) controls the speed of the engine (30) and the trunnion opening of the HST (14), thereby controlling the vehicle speed of the traveling vehicle body (2).

[0046] The controller (100) sets the vehicle speed mode to the first vehicle speed mode or the second vehicle speed mode in accordance with the operation of the setting switch (49). That is, the controller (100) sets the trunnion opening of the HST (14) to the first upper limit opening or the second upper limit opening in accordance with the operation state of the setting switch (49).

[0047] When the vehicle speed mode is a first vehicle speed mode, the controller (100) controls the trunnion opening of the HST (14) in accordance with the position (operation amount) of the main shift operation lever (36) so that the vehicle speed of the traveling vehicle body (2) becomes the vehicle speed corresponding to the position of the main shift operation lever (36). The controller (100) controls the trunnion opening of the HST (14) while setting the trunnion opening of the HST (14) to a first upper limit opening.

[0048] When the vehicle speed mode is the second vehicle speed mode, the controller (100) restricts the trunnion opening of the HST (14) to a second upper limit opening. As a result, the vehicle speed of the traveling vehicle body (2) is limited to a lower vehicle speed compared to when the vehicle speed mode is the first vehicle speed mode. The rotation speed of the engine (30) is set according to the position of the main shift operation lever (36).

[0049] The relationship between the position of the main transmission control lever (36), the trunnion opening, and the engine (30) rotation speed when the vehicle speed mode is the second vehicle speed mode will be described with reference to FIG. 7 . FIG. 7 is a diagram showing the relationship between the position of the main transmission control lever (36), the trunnion opening, and the engine (30) rotation speed. For the sake of explanation, FIG. 7 plots the trunnion opening and the engine (30) rotation speed on the vertical axis. FIG. 7 also shows the position of the main transmission control lever (36) between the neutral region (812) (see FIG. 4 ) and the forward travel region (811) (see FIG. 4 ). FIG. 7 also shows a portion of the trunnion opening in the first vehicle speed mode with a dashed line.

[0050] When the vehicle speed mode is the first vehicle speed mode, the trunnion opening degree increases as the position of the main transmission operation lever (36) moves from the neutral region (812) to the forwardmost side of the forward travel region (811). Also, the rotation speed of the engine (30) increases.

[0051] On the other hand, when the vehicle speed mode is the second vehicle speed mode, if the position of the main transmission operation lever (36) moves from the neutral region (812) to the forwardmost side of the forward travel region (811), the trunnion opening is restricted to the second upper limit opening. Note that, because the engine (30) rotational speed increases, the vehicle speed of the traveling vehicle body (2) also changes with the change in engine (30) rotational speed. However, because the trunnion opening is restricted to the second upper limit opening, the increase in the vehicle speed of the traveling vehicle body (2) is suppressed more than when the vehicle speed mode is the first vehicle speed mode. In other words, in the second vehicle speed mode, the trunnion opening is restricted, so the vehicle speed of the traveling vehicle body (2) does not increase with the trunnion opening, but the vehicle speed of the traveling vehicle body (2) increases slightly as the engine (30) rotational speed increases.

[0052] In this way, when the vehicle speed mode is the second vehicle speed mode, the trunnion opening is restricted to the second upper limit opening, thereby suppressing the vehicle speed of the traveling body (2). For example, when the main speed change lever (36) is in the forward most position in the forward traveling region (811) and the vehicle speed mode is the first vehicle speed mode, the seedling transplanter (1) can achieve high-speed traveling according to the position of the main speed change lever (36). When the main speed change lever (36) is in the forward most position in the forward traveling region (811) and the vehicle speed mode is the second vehicle speed mode, the seedling transplanter (1) can achieve low-speed traveling with the trunnion opening restricted.

[0053] Next, the process of setting the upper limit of the trunnion opening degree according to the embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the process of setting the upper limit of the trunnion opening degree according to the embodiment.

[0054] The controller (100) determines whether the setting switch (49) is in the first position (S100). If the setting switch (49) is in the first position (S100: Yes), the controller (100) sets the upper limit of the trunnion opening to the first upper limit (S101).

[0055] If the setting switch (49) is not in the first position (S100: No), i.e., if the setting switch (49) is in the second position, the controller (100) sets the upper limit of the trunnion opening to the second upper limit (S102).

[0056] The seedling transplanter (1) includes an engine (30), an HST (14), a main speed change lever (36), a setting switch (49), and a controller (100). The engine (30) is mounted on a traveling vehicle body (2). The HST (14) changes the speed of the power input from the engine (30) and outputs it. The main speed change lever (36) can adjust the trunnion opening of the HST (14) to adjust the vehicle speed of the traveling vehicle body (2). The setting switch (49) accepts an operation to change the upper limit of the trunnion opening of the HST (14) using the main speed change lever (36). The controller (100) sets the upper limit of the trunnion opening depending on the operating state of the setting switch (49).

[0057] This allows the seedling transplanter (1) to change the upper limit of the trunnion opening in response to the operation of the setting switch (49). For example, when the seedling transplanter (1) is being loaded onto a truck or otherwise moved on an inclined surface, the upper limit of the trunnion opening can be reduced to suppress the speed of the traveling body (2) and allow fine adjustments to be made regarding the traveling of the traveling body (2). Therefore, the seedling transplanter (1) can improve the safety of the operator.

[0058] The main speed change control lever (36) can also switch between forward and reverse travel of the traveling vehicle body (2). The controller (100) sets the upper limit of the trunnion opening when the traveling vehicle body (2) is moving forward and backward in response to the operation of the setting switch (49). The rotation speed of the engine (30) is set by the amount of operation of the main speed change control lever (36).

[0059] This allows the seedling transplanter (1) to set upper limits of the trunnion opening appropriate for forward and reverse travel. Therefore, the seedling transplanter (1) can fine-tune the travel of the traveling body (2) when traveling forward and reverse, improving operator safety. Furthermore, by setting the engine (30) speed according to the amount of operation of the main transmission control lever (36), the seedling transplanter (1) can, for example, increase the engine (30) speed on an inclined surface while restricting the trunnion opening and stabilizing the travel of the traveling body (2).

[0060] The controller (100) also 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, in accordance with 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 slower than in the first vehicle speed mode.

[0061] As a result, by setting the vehicle speed mode to the second vehicle speed mode, the seedling transplanter (1) can prevent the trunnion opening from becoming too large, thereby improving the safety of the operator.

[0062] The first upper limit opening degree and the second upper limit opening degree are different opening degrees when the traveling vehicle body (2) is moving forward and when it is moving backward. The second upper limit opening degree when moving backward in the second vehicle speed mode is smaller than the second upper limit opening degree when moving forward in the second vehicle speed mode.

[0063] This allows the seedling transplanter (1) to further improve the safety of the operator when reversing.

[0064] When the seedling transplanter (1) according to the modified example changes the vehicle speed mode from the second vehicle speed mode to the first vehicle speed mode, the second vehicle speed mode is released on the condition that the main speed change lever (36) is in the neutral region (812). For example, when the main speed change lever (36) is not in the neutral region (812), the vehicle speed mode is maintained in the second vehicle speed mode even if the setting switch (49) is operated from the second position to the first position.

[0065] As a result, the seedling transplanter (1) can suppress a sudden increase in speed of the traveling body (2) when the upper limit of the trunnion opening increases from the second upper limit to the first upper limit, thereby improving the safety of the operator.

[0066] The seedling transplanter (1) according to the modified 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 change to the second vehicle speed mode, but remains in the first vehicle speed mode.

[0067] As a result, the seedling transplanter (1) prevents the vehicle speed mode from switching to the second vehicle speed mode when the seedling planting device (55) is in an operating state. When the vehicle speed mode is switched to the second vehicle speed mode, it is assumed that the traveling vehicle body (2) will travel on a slope, for example, when being loaded onto a truck. In such a case, if the seedling planting device (55) is in an operating state, the seedling planting device (55) may hit the slope, possibly causing deterioration of the seedling planting device (55). By executing the second vehicle speed mode under the condition that the seedling transplanter (1) is in a predetermined non-ground operating state, deterioration of the seedling planting device (55) can be prevented.

[0068] The seedling transplanter (1) according to the modified example may execute the second vehicle speed mode on the condition that the float (62) is not in contact with the ground. The seedling transplanter (1) according to the modified example may execute the second vehicle speed mode on the condition that the auxiliary speed change lever (37) is in the planting position.

[0069] The seedling transplanter (1) according to the modified 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) through the operation of either the main speed change lever (36) or the accelerator pedal (110). The seedling transplanter (1) also controls the rotation speed of the engine (30) through the operation of the other of the main speed change lever (36) and the accelerator pedal (110). When the vehicle speed mode is set to the second vehicle speed mode in response to the operation of the setting switch (49), the upper limit of the output of the HST (14) is set by the operation of the main speed change lever (36) and the accelerator pedal (110).

[0070] As a result, the seedling transplanter (1) can control the output of the HST (14) and the rotation speed of the engine (30) by operating either the main speed control lever (36) or the accelerator pedal (110). Furthermore, the seedling transplanter (1) can control the rotation speed of the engine (30) by operating the other of the main speed control lever (36) and the accelerator pedal (110). Therefore, since the control targets for the operation of the main speed control lever (36) and the accelerator pedal (110) are different, the control targets that the operator desires to control can be differentiated by the operation of the main speed control lever (36) and the accelerator pedal (110). Therefore, the seedling transplanter (1) can improve the operator's maneuverability. Furthermore, when the vehicle speed mode is the second vehicle speed mode, the output of the HST (14) can be regulated by the operation of the main speed control lever (36) and the accelerator pedal (110), thereby improving the safety of the operator.

[0071] The seedling transplanter (1) according to the modified example may set the vehicle speed mode based on the tilt angle in the longitudinal direction of the traveling vehicle body (2) detected by the tilt sensor (92).

[0072] For example, when the tilt angle detected by the tilt 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 tilt angle is equal to or greater than the first predetermined angle, the controller (100) automatically sets the upper limit of the trunnion opening to the second upper limit. The first predetermined angle is a preset angle at which it can be determined that the traveling vehicle body (2) is on an inclined surface.

[0073] Furthermore, when the vehicle speed mode is the second vehicle speed mode and the tilt angle becomes less than the first predetermined angle, 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 tilt angle becomes small and becomes less than the first predetermined angle.

[0074] The controller (100) cancels the second vehicle speed mode when the main shift lever (36) enters the neutral region (812) or the accelerator pedal (110) is released while the vehicle speed mode is in the second vehicle speed mode. In other words, when the main shift lever (36) enters the neutral region (812) or the accelerator pedal (110) is released while the vehicle speed mode is in the second vehicle speed mode, the vehicle speed mode is changed from the second vehicle speed mode to the first vehicle speed mode.

[0075] As a result, when the inclination angle is equal to or greater than the first predetermined angle, the seedling transplanter (1) changes the vehicle speed mode to the second vehicle speed mode, thereby setting the upper limit of the trunnion opening to the second upper limit when traveling on an inclined surface, thereby improving the safety of the operator. Also, when the main speed change operation lever (36) is in the neutral region (812) and the accelerator pedal (110) is no longer operated, the seedling transplanter (1) changes the vehicle speed mode to the first vehicle speed mode, thereby suppressing a sudden increase in the speed of the traveling body (2), and improving the safety of the operator.

[0076] The first predetermined angle may be changeable. The first predetermined angle may be set by an operator or the like. This allows the operator to set the first predetermined angle according to an inclined surface, such as the angle of a running board used when loading the seedling transplanter (1) onto a truck. For example, the first predetermined angle may be set in increments of 0.1 degrees up to 15 degrees.

[0077] 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 / OFF state of the angle setting mode is set by an operator. The seedling transplanter (1) includes a switch for switching between angle setting modes. When the angle setting mode is ON, the controller (100) sets the angle measured by the tilt sensor (92) when the traveling vehicle body (2) enters a field to the first predetermined angle. For example, the controller (100) determines whether the traveling vehicle body (2) has entered a field based on position information detected by the position acquisition device (150). Furthermore, when the angle setting mode is ON and the traveling vehicle body (2) moves from a slope to flat ground, the controller (100) may set the angle on the slope to the first predetermined angle.

[0078] This allows the seedling transplanter (1) to set the first predetermined angle in accordance with the field.

[0079] The controller (100) of the seedling transplanter (1) according to the modified example deletes the reference data for automatic travel when the travel mode is automatic travel mode and the tilt angle is equal to or greater than a first predetermined angle. The reference data includes information on the orientation of the reference line, the straight travel path that serves as the reference for automatic straight travel in the field, the travel distance of the work process, and position information related to the work process.

[0080] This allows the seedling transplanter (1) to automatically delete the reference data of the field where it has worked when it finishes work in the field and is removed from the field, thereby preventing the seedling transplanter (1) from automatically traveling in another field using incorrect reference data.

[0081] The seedling transplanter (1) according to the modified example may change the trunnion opening so that the torque is low and the rotation speed of the engine (30) is high when the vehicle speed mode is the second vehicle speed mode and the tilt angle is equal to or greater than the second predetermined angle. For example, the seedling transplanter (1) reduces the trunnion opening.

[0082] When the vehicle speed mode is changed to the first vehicle speed mode or the second vehicle speed mode, the seedling transplanter (1) according to the modified example may be changed to the first vehicle speed mode or the second vehicle speed mode via a transition preparation mode, respectively. This allows the seedling transplanter (1) to suppress abrupt changes in vehicle speed when the vehicle speed mode is changed.

[0083] For example, when the vehicle speed mode is changed from the second vehicle speed mode to the first vehicle speed mode, the vehicle speed is restricted in the transition preparation mode 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 certain conditions, such as when the main transmission operating lever (36) is in the neutral region (812) or when the seedling planting section (4) is not in a predetermined lowered position.

[0084] Furthermore, when the vehicle speed mode is changed from the first vehicle speed mode to the second vehicle speed mode, there is no restriction on the vehicle speed in the transition preparation mode, and the vehicle speed mode is changed to the second vehicle speed mode under certain conditions. The specific conditions are, for example, when the main speed change operation lever (36) is in the neutral region (812) or when the sub-speed change operation lever (37) is in the planting speed position.

[0085] The seedling transplanter (1) according to the modified example may sound an alarm or display a message on a monitor when changing the vehicle speed mode. Also, the seedling transplanter (1) according to the modified example may turn on a lamp on the center mascot (66).

[0086] In the seedling transplanter (1) according to the modified example, the vehicle speed mode may be set to the second vehicle speed mode when the setting switch (49) is in the second position, the main speed change lever (36) is in the neutral region (812), the sub-speed change lever (37) is at the planting speed, the planting clutch (27a) is in the disengaged state, the float (62) is not grounded, and the safety switch is OFF (for example, the stop pedal is not depressed).

[0087] In the seedling transplanter (1) according to the modified example, when the vehicle speed mode is the second vehicle speed mode, the setting switch (49) is in the first position, the main shift control lever (36) is in the neutral region (812), and the trunnion of the HST (14) is in the neutral position, the vehicle speed mode may be set to the first vehicle speed mode.

[0088] The seedling transplanter (1) according to the modified example may be configured not to accept an operation to engage the planting clutch (27a) when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may be configured not to accept an operation to raise the seedling planting unit (4) when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may be configured not to accept an operation to lower the seedling planting unit (4) when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may be configured not to accept a control to raise the seedling planting unit (4) when the traveling body (2) moves backward when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may be configured not to accept a control to slightly lower the seedling planting unit (4) when the vehicle speed mode is the second vehicle speed mode.

[0089] In the seedling transplanter (1) according to the modified example, the HST (14) may be set to the neutral position when the main speed change lever (36) or the sub-speed change lever (37) is operated, thereby preventing the seedling transplanter (1) from suddenly starting due to erroneous operation.

[0090] In the seedling transplanter (1) according to the modified example, the vehicle speed mode may be set to the second vehicle speed mode when a slow speed switch different from the setting switch (49) is ON, the main speed change operation lever (36) is in the neutral region (812), and the machine is not in the tight-fitting control mode, is not in the tight-fitting planting control mode, is not in the straight-line assist mode, and is not in the turning assist mode.

[0091] The seedling transplanter (1) according to the modified example may not perform the close-fitting control when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may not perform the close-fitting planting control when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may not perform the straight-line assist control when the vehicle speed mode is the second vehicle speed mode. The seedling transplanter (1) according to the modified example may not perform the turning assist control when the vehicle speed mode is the second vehicle speed mode.

[0092] The seedling transplanter (1) according to the modified example may set the vehicle speed mode to the first vehicle speed mode when the ultra-low speed switch is OFF and the main speed change operation lever (36) is in the neutral region (812).

[0093] The seedling transplanter (1) according to the modified example may emit a warning sound by a buzzer or the like when the vehicle speed mode is the second vehicle speed mode and when traveling forward, the target value of the vehicle speed set by the main speed change operation lever (36) exceeds 20% of the vehicle speed in the first vehicle speed mode. The seedling transplanter (1) according to the modified example may be able to change the vehicle speed to be restricted when the vehicle speed mode is the second vehicle speed mode on the setting screen of the monitor.

[0094] The seedling transplanter (1) according to the modified example may emit a warning sound by a buzzer or the like when the vehicle speed mode is the second vehicle speed mode and the target value of the vehicle speed set by the main speed change lever (36) during reverse travel exceeds a vehicle speed that is 30% of the vehicle speed in the first vehicle speed mode. The seedling transplanter (1) according to the modified example may be able to change the vehicle speed limit when the vehicle speed mode is the second vehicle speed mode on a setting screen on the monitor.

[0095] The seedling transplanter (1) according to the modified example may be configured to set the vehicle speed mode to the second vehicle speed mode while the slow speed switch is pressed.

[0096] The seedling transplanter (1) according to the modified example may be provided with a forward slow speed switch and a reverse slow speed switch. The seedling transplanter (1) according to the modified example may set the HST (14) to a neutral position when neither the forward slow speed switch nor the reverse slow speed switch is pressed. The seedling transplanter (1) according to the modified example may set the HST (14) to a neutral position when both the forward slow speed switch and the reverse slow speed switch are pressed.

[0097] In the seedling transplanter (1) according to the modified example, when the HST motor (146) is operated to the acceleration side by operating the micro-speed switch, the response of the HST motor (146) may be made slower (less accelerated) than when the lever is operated normally.

[0098] In the seedling transplanter (1) according to the modified example, when the HST (14) is in the neutral position, the response of the HST motor (146) may be accelerated less (slower) than during normal lever operation.

[0099] The seedling transplanter (1) according to the modified example may increase the rotation speed of the engine (30) in accordance with the trunnion opening of the HST (14). For example, the seedling transplanter (1) controls the rotation speed of the engine (30) not only in accordance with the position of the main transmission operating lever (36) but also in accordance with the trunnion opening of the HST (14).

[0100] As a result, when the vehicle speed mode of the seedling transplanter (1) is the second vehicle speed mode, the rotation speed of the engine (30) is prevented from becoming too high, and fine adjustment of the vehicle speed becomes possible.

[0101] FIG. 9 is an explanatory diagram of a ridge crossing handle of an embodiment, with FIG. 9(A) being an overall explanatory diagram of the ridge crossing handle and FIG. 9(B) being an enlarged view of the slow speed switch. In FIG. 9, a ridge crossing handle (61) is supported on the front of the work vehicle (1). The ridge crossing handle (61) shown in FIG. 9 is composed of a U-shaped pipe extending diagonally upward in front of the work vehicle (1). The ridge crossing handle (61) can be pushed up and down by an operator who goes around to the front of the work vehicle (1) and grabs it (when not in the vehicle), causing the work vehicle (1) to tilt forward or backward. Therefore, it is possible to assist the work vehicle (1) in smoothly climbing over a convex portion such as a ridge.

[0102] A travel lever (620), which is an example of an operating tool, is supported on the ridge crossing handle (61). A slow speed switch (63), which is an example of a speed change tool, is disposed near the travel lever (620). The slow speed switch (63) shown in FIG. 9 is configured as a switch that switches between three positions: a forward position that limits the maximum forward speed to a predetermined forward speed limit (first speed limit), a reverse position that limits the maximum reverse speed to a predetermined reverse speed limit (second speed limit), and a neutral position that stops the work vehicle (1) without transmitting drive. In the slow speed switch (63) shown in FIG. 9, the forward position is located at the front and the reverse position is located at the rear in the fore-and-aft direction of the work vehicle (1), making it easy for workers to intuitively understand. The forward speed limit and reverse speed limit are set to a low speed (slow speed) that allows the worker to safely respond even if the work vehicle (1) moves while the worker is around in front of the work vehicle (1). In the embodiment shown in FIG. 9, the forward speed limit and the reverse speed limit are set to the same speed, but they may also be set to different speeds.

[0103] The fine-speed switch (63) shown in FIG. 9 is configured as a switch (a so-called momentary switch) that is operated in the forward or reverse position while being pressed to that position with a finger or hand, and returns to the neutral position when the finger is released. It is preferable, but not limited to, that the fine-speed switch (63) be a momentary switch. It is also possible to use a switch that does not return to the neutral position. If a reverse position is not required, it is also possible to use a switch with only two positions: forward and neutral. It is also possible to use any switch, such as a switch that switches between "forward," "neutral," and "reverse" each time the button is pressed, or a switch that switches to "forward" with a short press and to "reverse" with a long press.

[0104] In the seedling transplanter shown in FIG. 9 , the work vehicle (1) can start traveling at the forward or reverse speed limit by holding the travel lever (620) while pressing the forward or reverse position on the slow speed switch (63). Therefore, in the seedling transplanter shown in FIG. 9 , even if the travel lever (620) is held while the slow speed switch (63) is not operated, the work vehicle (1) will not travel. Furthermore, when the slow speed switch (63) is released, the slow speed switch (63) automatically returns to the neutral position, and the seedling transplanter stops traveling even if the travel lever (620) continues to be held. It is also possible to configure the work vehicle (1) not to immediately stop when the slow speed switch (63) is released, but to continue traveling if the slow speed switch (63) is pressed again within a predetermined time. This configuration improves workability because the work vehicle (1) does not immediately stop even if the finger accidentally releases the slow speed switch (63) due to a slippage or other reason.

[0105] In addition, even if the user releases his / her finger after operating the slow speed switch (63) to the forward or reverse position, if the travel lever (620) is gripped within a specified time, the vehicle will travel forward or backward at a slow speed. This eliminates the need to keep pressing the slow speed switch (63), thereby improving operability and workability.

[0106] When traveling at a very slow speed, it is preferable to activate a notification means such as a buzzer, a light, or a voice guide to notify those around the vehicle that the vehicle is traveling at a very slow speed. It is also preferable to install a sensor in the driver's seat (41) to detect occupancy, and to configure the vehicle so that the travel lever (620) and the very slow speed switch (63) cannot be operated when the driver's seat is detected. In other words, it is preferable to configure the work vehicle (1) so that the work vehicle does not travel even when the travel lever (620) or the very slow speed switch (63) is operated. Although the above example illustrates a configuration in which the control unit (300) (described below) transmits a control signal to the HST (14) to control it when the travel lever (620) is operated, this is not limiting. For example, it is also possible to directly connect the travel lever (620) and the HST (14) with a cable or the like, and directly operate the HST (14) when the travel lever (620) is operated. In this configuration, the vehicle speed can be changed depending on the amount of grip on the travel lever (620).

[0107] The HST control means controls the HST based on the operating position of the main transmission control lever (36) to control the traveling speed. The HST control means of the configuration shown in FIG. 9 controls the opening of the trunnion shaft of the HST to continuously control the gear ratio. The HST control means of the configuration shown in FIG. 9 also controls the opening of the trunnion shaft to change the gear ratio and also controls forward and reverse travel by switching the inclination angle of the swash plate linked to the trunnion shaft between positive and negative relative to the neutral angle. The trunnion shaft can be controlled using an actuator or a trunnion motor. The HST control means of the configuration shown in FIG. 9 controls the upper limit of the opening of the trunnion shaft when the ultra-low speed switch (63) is set to the forward or reverse position. Specifically, the upper limit of the opening of the trunnion shaft is limited to a limit opening (limit value) corresponding to the forward speed limit or reverse speed limit. The limit opening is set to a value lower than a reference opening (reference value) that does not limit speed during on-road travel, etc. In addition, in a state where the upper limit of the opening of the trunnion shaft is limited to the limited opening (creep speed travel standby state), the work vehicle (1) does not travel, and when the travel lever (620) is operated (gripped) in the creep speed travel standby state, the work vehicle (1) travels within the speed limit according to the operation state. In other words, in the creep speed travel standby state, the work vehicle (1) will not travel at a speed exceeding the speed limit even if the travel lever (620) is gripped.

[0108] The HST control means shown in FIG. 9 transitions to a slow-speed travel standby state when the main speed change lever (36) is operated to the neutral position, the work vehicle (1) is stopped, and the planting switch is set to "planting off" and the seedling planting unit (4) is stopped, and the slow-speed switch (63) is operated to the forward or reverse position. Therefore, when the main speed change lever (36) operated from the driver's seat (41) is not operated to the neutral position, when the work vehicle (1) is not stopped due to the straight-line assist being performed, or when the seedling planting unit (4) is operating, the HST control means does not transition to a slow-speed travel standby state even if the slow-speed switch (63) is operated. This prevents the work vehicle (1) from suddenly braking while traveling, even if the slow-speed switch (63) erroneously responds to flying stones or splashed mud during planting work or traveling. Therefore, sudden braking can be prevented from injuring the operator in the cockpit (41) or from disturbing the planting of seedlings.

[0109] Furthermore, when the travel lever (620) is operated in the slow-speed standby state, the HST control means of the embodiment shown in FIG. 9 allows the work vehicle (1) to travel within the speed limit. Furthermore, when the longitudinal inclination angle of the work vehicle (1) measured by the inclination detection means reaches a predetermined first angle (e.g., 5°) while traveling within the speed limit, the HST control means releases the control that limits the upper limit of the trunnion shaft opening to the limit value if the longitudinal inclination angle of the work vehicle (1) no longer reaches the first angle. That is, when traveling in the slow-speed standby state and the vehicle returns to the normal position after exceeding the first angle, the HST control means determines that the vehicle has crossed a convex portion such as a ridge or a slope for loading and unloading a truck, and releases the slow-speed standby state. Therefore, the state in which the travel speed was restricted is automatically released in a situation where it is highly likely that the vehicle has crossed a ridge or the like and is on a flat surface where travel at a normal speed is possible. That is, the slow-speed standby state is automatically released, and travel at a normal speed becomes possible, even without performing an operation to release the slow-speed standby state. If it is necessary to continue traveling at a slow speed, the slow speed switch (63) can be operated again.

[0110] Furthermore, the HST control means of the configuration shown in FIG. 9 determines that the seedling planting unit (4) is ready to start work when the planting switch is set to "Planting On" or when the float angle detection means detects that the float (62) has touched the ground, i.e., the seedling planting unit (4) is descending, and controls the upper limit of the trunnion shaft opening to a limit value, i.e., cancels the slow-speed standby state. When work is ready to start and slow-speed travel is no longer necessary, the slow-speed standby state is automatically canceled, improving workability compared to manually canceling the slow-speed standby state. For example, in a field with a turning slope (a so-called "turn farm road") formed at the outer edge of the field, simply traveling at slow speed on the turn farm road, then entering the field and lowering the seedling planting unit (4) automatically cancels the slow-speed standby state, improving workability compared to manually canceling the slow-speed standby state. The descent of the seedling planting section (4) can also be detected by a sensor provided on the lifting link mechanism (3).

[0111] In the seedling transplanter of the type shown in Figure 9 having the above configuration, when the slow speed switch (63) provided on the front ridge-crossing handle (61) of the work vehicle (1) is operated to the forward or reverse position and the travel lever (620) is operated, the work vehicle (1) travels at a slow speed. Therefore, compared to conventional technology that requires a seated operator to operate the speed change pedal, accidents such as tripping or falling are reduced, and operation at a slow speed is easier. Furthermore, operation of the travel lever (620) allows travel at a slow speed limit, making it easy to adjust the vehicle speed at low speeds, which is difficult to do with lever operation such as an HST lever.

Claims

1. A work vehicle comprising: an engine mounted on a traveling body; a hydraulic continuously variable transmission which changes the speed of and outputs the power input from the engine; and an operating device which can adjust the vehicle speed of the traveling body by adjusting the trunnion opening of the hydraulic continuously variable transmission, said trunnion opening being adjusted by said operating device within a range up to a set trunnion opening; and a setting device which accepts operation to change the set trunnion opening, wherein the engine speed is linked to the position of the operating device regardless of operation of the setting device.

2. A work vehicle as described in claim 1, characterized in that it has a first vehicle speed mode and a second vehicle speed mode that are set in response to operation of the setting device, the second vehicle speed mode is a mode in which the upper limit opening of the set trunnion opening is smaller than that of the first vehicle speed mode, and in the second vehicle speed mode, the set trunnion opening is reached halfway through the operating range of the operating device.

3. A work vehicle as described in claim 2, characterized in that after the set trunnion opening is reached, the operating tool is further operated to the speed increasing side, whereby the engine speed increases while the trunnion opening remains constant at the set trunnion opening.

4. A work vehicle as described in claim 2 or 3, characterized in that the second vehicle speed mode is released on condition that the operating device is in a neutral position and the setting device is set to a mode other than the second vehicle speed mode.

Images