Work vehicles

Abstract

To provide a work vehicle that can improve safety and operability in stepped gear shifting.SOLUTION: A rice transplanter 1 includes: a stepped variable transmission device 40 switched to any one of a plurality of shift positions for shifting power to be transmitted to travelling parts, which are front wheels 13 and rear wheels 14 from an engine 11 (power source); a speed change lever 18 (stepped speed change operation part) for receiving a switching operation of the stepped variable transmission device 40; and a speed change control part 70 for controlling switch drive of the stepped variable transmission device 40 on the basis of a result of detection of the switching operation by the speed change lever 18. The speed change control part 70 starts deceleration of the travelling parts according to the switching operation by the speed change lever 18, waits for the switch drive of the stepped variable transmission device 40 corresponding to the switching operation by the speed change lever 18 until the travelling speed of the travelling parts becomes a predetermined speed threshold or lower while allowing the switch drive of the stepped variable transmission device 40 corresponding to the switching operation by the speed change lever 18 with a driving speed of the travelling parts becoming a predetermined speed threshold or lower as a switch condition.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a work vehicle equipped with a stepped transmission having a plurality of shift positions.

Background Art

[0002] Conventionally, work vehicles such as rice transplanters are equipped with a continuously variable transmission that continuously changes the power transmitted from the power source to the traveling unit, or a stepped transmission that has a plurality of shift positions and changes gears stepwise. The stepped transmission has, for example, a plurality of shift positions including a forward position, a neutral position, a reverse position, etc. for switching between forward and reverse, or a low-speed position, a medium-speed position, a high-speed position, etc. for switching speed steps. The work vehicle includes an actuator (shift drive member) that performs a switching drive to switch the stepped transmission to any one of the shift positions, and a shift lever (stepped shift operation unit) that receives a switching operation of the stepped transmission. The work vehicle detects the operation position of the shift lever and performs a switching drive of the stepped transmission by driving the actuator according to the detection result.

[0003] For example, the traveling vehicle body disclosed in Patent Document 1 is provided with a main clutch for turning on and off the drive to the drive wheels, a brake device for braking the drive wheels, and a shift lever for shifting the transmission that changes the drive to the drive wheels and stops the drive, and operates the actuator by operating the shift lever to shift the transmission. The traveling vehicle body is provided with a linkage mechanism that disengages the main clutch and brakes the brake device by the operation of the actuator when the shift lever is operated to the neutral position where the drive is stopped.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In work vehicles, actuators are used to drive the stepped transmission, but since the speed difference is large when switching between forward and reverse or between speed gears using the stepped transmission, driving the stepped transmission while in motion can cause damage to the drivetrain and sudden acceleration / deceleration, reducing safety.

[0006] Furthermore, in conventional work vehicles such as those described in Patent Document 1, when shifting to the neutral position, which does not transmit power to the drive wheels, the vehicle is braked and stopped by the brake system before shifting to the neutral position. As a result, it is not possible to shift to the next gear position after the neutral position while the work vehicle is decelerating and coming to a stop, which reduces operability.

[0007] The present invention aims to provide a work vehicle that can improve safety and operability during stepped gear changes. [Means for solving the problem]

[0008] To solve the above problems, the work vehicle of the present invention comprises a stepped transmission that changes the speed of power transmitted from a power source to a drive unit by switching to one of a plurality of gear positions, a stepped transmission operation unit that receives a switching operation of the stepped transmission, and a control unit that controls the switching drive of the stepped transmission based on the detection result of the switching operation by the stepped transmission operation unit. The control unit starts decelerating the drive unit in response to the switching operation by the stepped transmission operation unit, and waits for the switching drive of the stepped transmission corresponding to the switching operation by the stepped transmission operation unit until the drive speed of the drive unit falls below a predetermined speed threshold, while allowing the switching drive of the stepped transmission corresponding to the switching operation by the stepped transmission operation unit when the drive speed of the drive unit falls below the predetermined speed threshold as a switching condition. [Effects of the Invention]

[0009] The present invention provides a work vehicle that can improve safety and operability when using stepped gears. [Brief explanation of the drawing]

[0010] [Figure 1] This is a left side view showing a rice transplanter according to an embodiment of the present invention. [Figure 2] This is a top view showing the gear shift lever of a rice transplanter according to an embodiment of the present invention. [Figure 3] This is a perspective view from above of the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 4] This is a perspective view from below showing the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 5] This is a top view showing the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 6] This is a transmission mechanism diagram showing the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 7] This is a cross-sectional view showing the main speed shifting member in the transmission of a rice transplanter according to an embodiment of the present invention, viewed from the side. [Figure 8] Block diagram showing a rice transplanter according to an embodiment of the present invention. [Figure 9] This is a timing chart showing an example of the operation of a rice transplanter according to an embodiment of the present invention. [Figure 10] This flowchart shows an example of the operation of a rice transplanter according to an embodiment of the present invention. [Figure 11] This is a timing chart showing an example of operation of a stepped transmission according to another example of the present invention. [Figure 12] This is a timing chart showing an example of operation of a stepped transmission according to another example of the present invention. [Modes for carrying out the invention]

[0011] A rice transplanter 1, which is an embodiment of the work vehicle of the present invention, will be described with reference to the drawings. As shown in Figure 1, the rice transplanter 1 comprises a vehicle body 2 and a planting unit 3, and is configured to perform seedling planting work by the planting unit 3 while the vehicle body 2 moves. Furthermore, as shown in Figure 8, the rice transplanter 1 is equipped with a control device 4 for controlling the vehicle body 2 and the planting unit 3.

[0012] The vehicle body part 2 includes a body frame 10, an engine 11 (power source) which is a power source attached to the front part of the body frame 10 near the center in the left - right direction, and a transmission 12 (speed change device). As a traveling part, the vehicle body part 2 includes a pair of front wheels 13 rotatably attached to the front part of the body frame 10 at both ends in the left - right direction, and a pair of rear wheels 14 rotatably attached to the rear part of the body frame 10 at both ends in the left - right direction.

[0013] The vehicle body part 2 has a driver's seat 15 near the center on the body frame 10, and around the driver's seat 15, there are driving operation tools such as a steering wheel 16, a shift pedal 17, a shift lever 18, etc. The vehicle body part 2 has a plurality of spare seedling tables 19 on the body frame 10.

[0014] The engine 11 generates rotational power to drive each part and is covered from above by a bonnet 20. The transmission 12 is connected to the engine 11, shifts the power of the engine 11, and transmits it to the traveling part consisting of a pair of front wheels 13 and a pair of rear wheels 14. As shown in FIGS. 3 - 6, the transmission 12 includes a continuously variable transmission 30 that continuously shifts the power from the engine 11 and a stepped transmission 40 that has a plurality of shift positions and shifts step - by - step. Also, the transmission 12 is connected to a power take - off shaft (PTO shaft) 21 provided at the rear part of the vehicle body part 2, and transmits the power of the engine 11 to the planting part 3 via the PTO shaft 21. Details of the transmission 12 will be described later.

[0015] The pair of front wheels 13 and the pair of rear wheels 14 rotate and drive according to the power transmitted from the engine 11 and the transmission 12, and cause the vehicle body part 2 to travel forward or backward. Also, the pair of front wheels 13 are steered and driven according to the operation of the steering wheel 16 to steer the vehicle body part 2.

[0016] The steering wheel 16 is arranged in front of the driver's seat 15 and behind the bonnet 20, and the steering transmitted to the pair of front wheels 13 is adjusted according to the rotational operation of the steering wheel 16 by the operator. The shift pedal 17 is a continuously variable transmission operation unit that receives the adjustment operation of the continuously variable transmission 30 of the transmission 12, and is arranged at the lower front part of the driver's seat 15. A continuously variable operation detection unit 17a (see FIG. 8) for detecting adjustment operations such as depression by the operator is provided for the shift pedal 17, and the control device 4 controls the continuously variable transmission 30 based on the detection result of the continuously variable operation detection unit 17a, so that the power transmitted to the traveling unit composed of the pair of front wheels 13 and the pair of rear wheels 14 is adjusted continuously. The continuously variable operation detection unit 17a is configured to be able to detect the opening degree of the shift pedal 17. Note that when there is no depression of the shift pedal 17, the opening degree is 0%, and when the depression is maximum (MAX), the opening degree is fully open (100%).

[0017] The shift lever 18 is a stepped transmission operation unit that receives the switching operation of the stepped transmission 40 of the transmission 12, and is arranged on the left side of the steering wheel 16. A stepped operation detection unit 18a (see FIG. 8) for detecting the shifting operation by the operator is provided for the shift lever 18, and the control device 4 controls the stepped transmission 40 based on the detection result of the stepped operation detection unit 18a, so that the stepped transmission 40 is switched to any one of a plurality of shift positions. The stepped operation detection unit 18a is composed of, for example, a lever position sensor provided at the fulcrum of the shift lever 18. The shift lever 18 receives a main shift operation for switching the forward travel, reverse travel, and stop of the rice transplanter 1, and a sub-shift operation for switching the planting travel and the moving travel as the switching operation of the stepped transmission 40. Note that when the shift lever 18 is switched to the moving travel, the traveling direction of the rice transplanter 1 is the same as that of the planting travel by the transmission 12, but by changing the gear ratio, a driving force faster than the planting travel can be transmitted to the traveling unit.

[0018] The gear shift lever 18 has multiple operating positions. For example, as shown in Figure 2, the main gear shift operating positions include forward operation 18b, neutral operation 18c, and reverse operation 18d, while the sub-gear shift operating positions include planting operation 18e and movement operation 18f. Note that the forward operation 18b, which corresponds to forward driving, and the planting operation 18e, which corresponds to planting driving, may be the same operating position. The gear shift lever 18 may also have a seedling grafting operation 18g as a sub-gear shift operating position.

[0019] The planting unit 3 is located at the rear of the vehicle body 2 and is connected to the vehicle body 2 via a lifting link mechanism 22, which allows the planting unit 3 to be raised and lowered relative to the vehicle body 2. The planting unit 3 comprises a planting input case section 23, a plurality (for example, three) of planting units 24, a seedling tray 25, and a plurality of floats 26. The planting unit 3 is configured to sequentially supply seedlings from the seedling tray 25 to each planting unit 24, and to perform planting work in multiple rows using the plurality of planting units 24. The planting input case section 23 is configured to transmit power transmitted from the transmission 12 via the PTO shaft 21 to the plurality of planting units 24.

[0020] Multiple planting units 24 are arranged at intervals in the left-right direction, and each planting unit 24 comprises a planting transmission case section 27 and a rotating case section 28. The front of the planting transmission case section 27 is connected to the planting input case section 23, and power is transmitted through the planting input case section 23. The rotating case sections 28 are provided on both the left and right sides of the planting transmission case section 27 and are rotatably attached to the rear of the planting transmission case section 27. Two planting claws 29 are attached to the left-right outer side of each rotating case section 28 (opposite the side of the planting transmission case section 27).

[0021] The two planting claws 29 are rotatably mounted on the rotating case section 28 at both ends of the rotating case section 28, spaced apart from the axis of rotation of the rotating case section 28 relative to the planting transmission case section 27. As the rotating case section 28 rotates relative to the planting transmission case section 27, the two planting claws 29 rotate around the axis of rotation of the rotating case section 28. At this time, each planting claw 29 rotates while passing through a scraping position for scraping seedlings from the seedling mat on the seedling tray 25 and a planting position for planting seedlings in the field.

[0022] The seedling tray 25 is positioned in front of and above the multiple planting units 24 and is configured to hold seedling mats. The float 26 is pivotably mounted below the planting section 3, and the lower surface of the float 26 contacts the field surface, stabilizing the planting position of the planting section 3 relative to the field surface.

[0023] Next, the transmission 12 will be explained with reference to Figures 3 to 7.

[0024] In the transmission 12, the continuously variable transmission 30 transmits power from the engine 11 to the stepped transmission 40 by continuously changing the speed. For example, as shown in Figures 3 to 6, the continuously variable transmission 30 is configured as a hydraulic mechanical transmission (HMT) by comprising a hydraulic continuously variable transmission 31 (HST) and a planetary gear mechanism 32. The hydraulic continuously variable transmission 31 is connected to the planetary gear mechanism 32 and transmits power from the engine 11 to the planetary gear mechanism 32 by continuously changing the speed. The planetary gear mechanism 32 is composed of planetary gears, etc., and is connected to the main transmission shaft 41 provided in the stepped transmission 40, and transmits power from the hydraulic continuously variable transmission 31 to the main transmission shaft 41, causing the main transmission shaft 41 to rotate.

[0025] The continuously variable transmission 30 includes a continuously variable transmission drive member 33 (see Figure 8), such as an actuator, which adjusts and drives the hydraulic continuously variable transmission 31. The continuously variable transmission drive member 33 is controlled by the control device 4 to adjust and drive the hydraulic continuously variable transmission 31 and change the power.

[0026] In the transmission 12, the stepped transmission 40 includes a main transmission shaft 41, a sub-transmission shaft 42, a reverse transmission shaft 43, and a brake 44. The main transmission shaft 41 is provided with a main transmission member 45 and a first PTO gear 46, and the sub-transmission shaft 42 is provided with a sub-transmission member 47, a first transmission gear 48, a second transmission gear 49, and a second PTO gear 50. The reverse transmission shaft 43 is provided with a reverse gear 51.

[0027] The main transmission member 45 has multiple transmission positions: a forward position, a neutral position, and a reverse position. It switches to any of these transmission positions to change the speed of the power transmitted from the main transmission shaft 41. The main transmission member 45 may be composed of any transmission means, such as a ball clutch or a slide gear, but in this embodiment, as shown in Figure 7, an example in which it is composed of a ball clutch is shown.

[0028] When the main transmission member 45 is switched to the forward position, the main transmission shaft 41 is connected to the main transmission shaft forward gear 66, and power is transmitted from the main transmission shaft forward gear 66 to the auxiliary transmission shaft 42 via the auxiliary transmission member 47. When the main transmission member 45 is switched to the reverse position, the main transmission shaft 41 is connected to the main transmission shaft reverse gear 67, and power is transmitted from the main transmission shaft reverse gear 67 to the reverse transmission shaft 43 via the reverse gear 51. The reverse gear 51 is also connected (measuring) to the first transmission gear 48 of the auxiliary transmission shaft 42, and power is transmitted to the auxiliary transmission shaft 42 via the first transmission gear 48. When the main transmission member 45 is switched to the neutral position, the main transmission shaft 41 is not connected to either the main transmission shaft forward gear 66 or the main transmission shaft reverse gear 67, and power is not transmitted.

[0029] A main transmission drive member 52, such as an actuator that performs switching drive, is attached to the main transmission member 45, and the main transmission drive member 52 is controlled by the control device 4 to perform switching drive of the main transmission member 45. For example, the main transmission member 45, which consists of a ball clutch, is configured as shown in Figure 7 with two balls 45a corresponding to the main transmission shaft forward gear 66 and the main transmission shaft reverse gear 67, respectively, a shifter 45b that shifts in accordance with the drive of the main transmission drive member 52, and a ball engaging member 45c.

[0030] The ball engaging member 45c is an annular member provided on the outer circumferential surface of the main transmission shaft 41. The outer circumferential surface of the ball engaging member 45c has rows of recesses 45d arranged circumferentially for accommodating balls 45a, and these rows are provided at two locations in the axial direction. Note that one row of recesses 45d and the other row of recesses 45d have recesses at different positions in the circumferential direction.

[0031] Furthermore, the main transmission member 45 has a first sleeve 66a having a main transmission shaft forward gear 66 and a second sleeve 67a having a main transmission shaft reverse gear 67, and the first sleeve 66a and the second sleeve 67a are provided so as to surround the main transmission shaft 41. The ball 45a corresponding to the main transmission shaft forward gear 66 is held in a through hole 66b formed in the first sleeve 66a, and the ball 45a corresponding to the main transmission shaft reverse gear 67 is held in a through hole 67b formed in the second sleeve 67a.

[0032] The shifter 45b is formed in an annular shape that surrounds the first sleeve 66a and the second sleeve 67a, and is configured to slide axially across the first sleeve 66a and the second sleeve 67a. An annular cavity 45e is formed on the inner circumferential surface of the shifter 45b at its axial center.

[0033] When the shifter 45b is shifted to the neutral shift position, as shown in Figure 7, the cavity 45e of the shifter 45b is positioned to straddle the through hole 66b of the first sleeve 66a and the through hole 67b of the second sleeve 67a, and each ball 45a is released into the cavity 45e. As a result, neither the first sleeve 66a nor the second sleeve 67a is fixed to the main transmission shaft 41, and neither the main transmission shaft forward gear 66 nor the main transmission shaft reverse gear 67 is fixed (connected) to the main transmission shaft 41, making power transmission from the main transmission shaft 41 impossible.

[0034] When the shifter 45b is shifted to the forward shift position on the second sleeve 67a side from the neutral shift position, the end of the shifter 45b on the first sleeve 66a side is positioned to correspond to the through hole 66b of the first sleeve 66a, and the ball 45a in the through hole 66b is pushed into the recess row 45d, thereby fixing the first sleeve 66a to the main transmission shaft 41, fixing (connecting) the main transmission shaft forward gear 66 to the main transmission shaft 41, and enabling power transmission from the main transmission shaft 41 to the sub-transmission shaft 42. In addition, the through hole 67b of the second sleeve 67a is positioned to correspond to the cavity 45e of the shifter 45b, and the ball 45a in the through hole 67b is released into the cavity 45e, so the second sleeve 67a is not fixed to the main transmission shaft 41, and therefore the main transmission shaft reverse gear 67 is not fixed (connected) to the main transmission shaft 41.

[0035] When the shifter 45b is shifted to the reverse shift position on the first sleeve 66a side from the neutral shift position, the end of the shifter 45b on the second sleeve 67a side is positioned to correspond to the through hole 67b of the second sleeve 67a, and the ball 45a in the through hole 67b is pushed into the recess row 45d, thereby fixing the second sleeve 67a to the main transmission shaft 41, fixing (connecting) the main transmission shaft reverse gear 67 to the main transmission shaft 41, and enabling power transmission from the main transmission shaft 41 to the sub-transmission shaft 42. Note that the through hole 66b of the first sleeve 66a is positioned to correspond to the cavity 45e of the shifter 45b, and the ball 45a in the through hole 66b is released into the cavity 45e, so the first sleeve 66a is not fixed to the main transmission shaft 41, and therefore the main transmission shaft forward gear 66 is not fixed (connected) to the main transmission shaft 41.

[0036] The auxiliary transmission member 47 has multiple gear shift positions, including a planting position and a moving position, and switches to any of these gear shift positions to change the speed of the power transmitted to the auxiliary transmission shaft 42. The auxiliary transmission member 47 may be composed of any gear shifting means, such as a slide gear, but in this embodiment, an example in which it is composed of a slide gear is shown.

[0037] The auxiliary transmission member 47 is composed of a slide gear having a relatively large-diameter planting gear 47a corresponding to the planting position and a relatively small-diameter moving gear 47b corresponding to the moving position. When the auxiliary transmission member 47 is switched to the planting position, the large-diameter planting gear 47a is connected (meets) with the main transmission shaft forward gear 66, transmitting power to the auxiliary transmission shaft 42 at a relatively low speed. When the auxiliary transmission member 47 is switched to the moving position, the small-diameter moving gear 47b is connected (meets) with the main transmission shaft forward gear 66, transmitting power to the auxiliary transmission shaft 42 at a relatively high speed. An auxiliary transmission drive member 53, such as an actuator that performs the switching drive, is attached to the auxiliary transmission member 47, and the auxiliary transmission drive member 53 is controlled by the control device 4 to perform the switching drive of the auxiliary transmission member 47.

[0038] The second transmission gear 49 of the auxiliary transmission shaft 42 is connected (meets) with the front wheel output gear 55 provided on the front wheel output shaft 54, and transmits the power transmitted to the auxiliary transmission shaft 42 to the front wheel output shaft 54 ​​via the front wheel output gear 55. In addition, the first transmission gear 48 of the auxiliary transmission shaft 42 is connected (meets) with the rear wheel output gear 60 provided on the rear wheel output shaft 59 via the third transmission gear 56, fourth transmission gear 57, fifth transmission gear 58, etc., and transmits the power transmitted to the auxiliary transmission shaft 42 to the rear wheel output shaft 59 via the rear wheel output gear 60.

[0039] The first PTO gear 46 of the main transmission shaft 41 is connected (meets) with the second PTO gear 50 of the auxiliary transmission shaft 42, and transmits the power transmitted to the main transmission shaft 41 to the auxiliary transmission shaft 42 via the second PTO gear 50. Furthermore, the second PTO gear 50 of the auxiliary transmission shaft 42 is connected (meets) with the PTO output gear 64 provided on the PTO output shaft 63 via the sixth transmission gear 61, the seventh transmission gear 62, etc., and transmits the power transmitted to the auxiliary transmission shaft 42 to the PTO output shaft 63 via the PTO output gear 64.

[0040] The brake 44 is attached to the auxiliary transmission shaft 42 and, when activated, brakes the rotation of the auxiliary transmission shaft 42 and restricts the transmission of power. The brake 44 is fitted with a brake drive member 65, such as an actuator, which switches between an activated (ON) state and an activated (OFF) state. The brake drive member 65 is controlled by the control device 4 to switch between the activated and deactivated states of the brake 44 in response to the operation of a brake operating member (not shown) or to the drive to switch the stepped transmission 40 to the neutral position.

[0041] Next, the control unit 4 will be described. As shown in Figure 8, the control unit 4 is composed of a computer such as a CPU and is connected to storage units 5 such as ROM, RAM, hard disk drive, and flash memory.

[0042] The memory unit 5 stores programs and data for controlling various components and functions of the rice transplanter 1, and the control device 4 controls the various components and functions by performing calculations based on the programs and data stored in the memory unit 5.

[0043] The control device 4 operates as a gear shift control unit 70 (control unit) by executing a program stored in the memory unit 5. The gear shift control unit 70 controls gear shifting by the continuously variable transmission 30 and gear shifting by the stepped transmission 40. The gear shift control unit 70 implements the gear shift control process of the gear shift control method according to the present invention.

[0044] The gear shift control unit 70 controls the gear shift of the continuously variable transmission 30 by detecting the operation state of the gear shift pedal 17's adjustment operation of the continuously variable transmission 30 using the continuously variable operation detection unit 17a, and adjusting and driving the continuously variable transmission drive member 33 based on the detection result to control the continuously variable transmission 30. In this way, the gear shift control unit 70 continuously adjusts the power transmitted from the engine 11 to the running gears of the pair of front wheels 13 and the pair of rear wheels 14. For example, the gear shift control unit 70 detects the opening degree of the gear shift pedal 17 using the continuously variable operation detection unit 17a and controls the power of the continuously variable transmission 30 to change according to the opening degree of the gear shift pedal 17.

[0045] Furthermore, when the gear shift control unit 18a detects that a switching operation of the stepped gear shift device 40 has been performed by the gear shift lever 18, the gear shift control unit 70 controls the continuously variable transmission 30 to reduce the power transmitted to the running gear. For example, when the rice transplanter 1 is running, the gear shift control unit 70 detects that a switching operation has been performed by the gear shift lever 18, specifically that the gear shift lever 18 has been switched from forward operation 18b or reverse operation 18d to another operation position, and reduces the power transmitted to the running gear by reducing the power of the continuously variable transmission 30. At this time, the gear shift control unit 70 should gradually reduce the power of the continuously variable transmission 30 by gradually lowering the set speed related to the running speed of the rice transplanter 1 and the set speed related to the drive speed (rotation speed) of the continuously variable transmission 30.

[0046] Furthermore, if the gear shift control unit 70 detects that a gear shift operation of the gear shift lever 18 has been performed on the gear shift device 40 using the gear shift lever 18, it disables the adjustment operation of the continuously variable transmission 30 using the gear shift pedal 17. In other words, the gear shift control unit 70 automatically controls the continuously variable transmission 30 to reduce power regardless of the operation state of the gear shift pedal 17.

[0047] Subsequently, when the gear position switching drive of the stepped transmission 40 is completed in response to the switching operation by the gear lever 18, the gear control unit 70 notifies the operator of the completion of the gear shift by displaying on a display (not shown) or by outputting sound by a speaker (not shown). Furthermore, in this case, the gear control unit 70 activates the adjustment operation of the continuously variable transmission 30 by the gear pedal 17 in accordance with a predetermined operation of the gear pedal 17. For example, the gear control unit 70 detects the operation state of the gear pedal 17 with the continuously variable operation detection unit 17a, and activates the gear pedal 17 when a predetermined operation is performed in which the gear pedal 17 is returned to a specified value or less (an operation in which the opening degree of the gear pedal 17 becomes 30% or less of the fully open position).

[0048] The gear shift control unit 70, in order to control the gear shift of the stepped transmission 40, basically detects the operation status of the gear shift operation of the stepped transmission 40 by the gear shift lever 18 using the stepped operation detection unit 18a, and controls the stepped transmission 40 by switching the main gear shift drive member 52 and the sub-gear shift drive member 53 based on the detection result. As a result, the gear shift control unit 70 shifts the power transmitted from the engine 11 to the running gears of the pair of front wheels 13 and the pair of rear wheels 14 to one of the multiple gear positions.

[0049] For example, when the gear lever 18 is switched to forward operation 18b, neutral operation 18c, or reverse operation 18d, the gear shift control unit 70 controls the main gear shift drive member 52 to switch the main gear shift member 45 to the corresponding forward position, neutral position, or reverse position to change the power of the stepped transmission 40. Also, when the gear lever 18 is switched to planting operation 18e or moving operation 18f, the gear shift control unit 70 controls the sub-gear shift drive member 53 to switch the sub-gear shift member 47 to the corresponding planting position or moving position to change the power of the stepped transmission 40. Furthermore, when the gear shift lever 18 is switched to the seedling grafting operation 18g, the gear shift control unit 70 controls the power of the stepped transmission 40 by switching the main gear shift member 45 to the neutral position using the main gear shift drive member 52 and switching the auxiliary gear shift member 47 to the moving position using the auxiliary gear shift drive member 53.

[0050] In this embodiment, in particular, when the gear shift control unit 18a detects that a switching operation of the stepped transmission 40 has been performed by the gear shift lever 18, the gear shift control unit 70 waits without performing the switching drive of the stepped transmission 40 corresponding to the switching operation by the gear shift lever 18 until the drive speed of the traveling section of the rice transplanter 1 falls below a predetermined speed threshold. Then, the gear shift control unit 70 allows the switching drive of the stepped transmission 40 corresponding to the switching operation by the gear shift lever 18, using the driving speed of the traveling section falling below a predetermined speed threshold as the switching condition. The gear shift control unit 70 obtains the drive speed of the power output by the continuously variable transmission 30 as the drive speed of the traveling section, and for example, detects the rotation position of the operating motor (not shown) of the continuously variable transmission 30 with a potentiometer (not shown) and obtains the drive speed based on the detection result. It is preferable to set the speed threshold to a speed that does not cause damage to the drive system or sudden acceleration / deceleration due to gear shifting. The speed threshold is set to a value greater than 0.

[0051] At this time, the gear shift control unit 70 sets a predetermined speed threshold according to the current (before shifting) gear position of the stepped transmission 40. For example, an operator may perform a shifting operation via the neutral operation 18c using the gear shift lever 18 to switch the stepped transmission 40 from the current gear position (e.g., forward or reverse position) to the target gear position (e.g., reverse or forward position) via the neutral position (for example, switching from forward operation 18b to reverse operation 18d via neutral operation 18c, or switching from reverse operation 18d to forward operation 18b via neutral operation 18c). In this case, the gear shift control unit 70 allows the stepped transmission 40 to switch from the current gear position to the neutral position, with the driving speed of the running unit being less than or equal to a first speed threshold V1 (e.g., 0.4 m / s) as a predetermined speed threshold, and also allows the stepped transmission 40 to switch from the neutral position to the target gear position, with the driving speed of the running unit being less than or equal to a second speed threshold V2 (e.g., 0.2 m / s), which is smaller than the first speed threshold V1, as a predetermined speed threshold. Alternatively, the gear shift control unit 70 may set the same switching conditions as above based on the operating amount of the continuously variable transmission 30 (e.g., the operating amount of the HMT operating actuator such as the continuously variable transmission drive member 33), and allow the stepped transmission 40 to switch from the current gear position to the neutral position, and also allow the stepped transmission 40 to switch from the neutral position to the target gear position.

[0052] Furthermore, when the gear shift control unit 18a detects that a gear shift operation of the gear shift lever 18 has been performed on the gear shift device 40, the gear shift control unit 70 automatically controls the brakes 44 to be activated by the brake drive member 65, with the driving speed of the travel section of the rice transplanter 1 being less than or equal to a predetermined braking speed V3 as the braking condition. At this time, the gear shift control unit 70 sets, as a switching condition that allows the gear shift drive of the gear shift device 40 in response to the gear shift operation of the gear shift lever 18, the driving speed of the travel section being less than or equal to a predetermined speed threshold, in addition to the condition that the brakes 44 are activated by the brake drive member 65.

[0053] For example, a brake operation detection unit 44a (see Figure 8) is provided for the brake 44 to detect the operation of the brake 44, and the gear shift control unit 70 determines that the brake 44 is operating based on the detection result of the brake operation detection unit 44a. After controlling the brake 44 to operate, the gear shift control unit 70 automatically controls the brake drive member 65 to release the brake 44 and put it into a non-operating state when the stepped transmission 40 has completed shifting and a predetermined operation of the gear shift pedal 17 has been performed. If the predetermined operation of the gear shift pedal 17 has been performed before the stepped transmission 40 has completed shifting, the gear shift control unit 70 may control the brake drive member 65 to release the brake 44 and put it into a non-operating state when the stepped transmission 40 has completed shifting. The braking speed V3 may be the same value as the first speed threshold V1, or it may be a value slightly larger than the first speed threshold V1.

[0054] Next, an example of the operation of shifting the speed of the stepped transmission 40 in the rice transplanter 1 will be explained with reference to the timing chart in Figure 9 and the flowchart in Figure 10. In the timing chart in Figure 9, the travel speed of the rice transplanter 1 and the drive speed of the continuously variable transmission 30 are shown in correspondence and superimposed, with the travel speed shown by a dashed line and the drive speed shown by a solid line. In addition, the timing chart in Figure 9 shows the opening degree of the shift pedal 17, the operating state of the shift lever 18, and the operating state of the brake 44. Furthermore, in the timing chart in Figure 9, the operating state of the main shift drive member 52 and the operating state of the main shift member 45 of the stepped transmission 40 are shown in correspondence and superimposed, with the operating state of the main shift drive member 52 shown by a solid line and the operating state of the main shift member 45 shown by a dashed line.

[0055] First, while the rice transplanter 1 is moving forward with the gear lever 18 set to forward operation 18b (S1 in Figure 10), the operator switches the gear lever 18 from forward operation 18b to neutral operation 18c (T1 in Figure 9), and then switches it to reverse operation 18d (T2 in Figure 9, S2 in Figure 10).

[0056] In response to the switching operation of the gear shift lever 18, the gear shift control unit 70 automatically controls the continuously variable transmission 30 to reduce the power transmitted to the stepped gear shift 40, regardless of the operation state of the gear shift pedal 17, and also disables the adjustment operation of the continuously variable transmission 30 by the gear shift pedal 17 (T1 in Figure 9, S3 in Figure 10).

[0057] Subsequently, when the driving speed of the running section falls below a predetermined braking speed V3 (T3 in Figure 9, S4 in Figure 10: Yes), the gear shift control unit 70 automatically controls the brake drive member 65 to activate the brake 44 (S5 in Figure 10).

[0058] Furthermore, when the drive speed of the running section falls below the first speed threshold V1 (T4 in Figure 9, S6 in Figure 10: Yes) and the operation of the brake 44 is detected, the gear shift control unit 70 allows the stepped gear shift device 40 to switch from the forward position, which is the current gear shift position, to the neutral position, and switches the main gear shift drive member 52 to shift the main gear shift member 45 from the forward position to the neutral position (S7 in Figure 10).

[0059] Furthermore, when the drive speed of the running section falls below the second speed threshold V2 (T5 in Figure 9, S8 in Figure 10: Yes) and the operation of the brake 44 is detected, the gear shift control unit 70 allows the stepped gear shift device 40 to switch from the neutral position to the reverse position, and switches the main gear shift drive member 52 to shift the main gear shift member 45 from the neutral position to the reverse position (S9 in Figure 10).

[0060] Then, when the gear shifting drive of the stepped transmission 40, which corresponds to the gear shifting operation by the gear shift lever 18, is completed and the gear shift is finished, the gear shift control unit 70 notifies the operator that the gear shift is complete (T6 in Figure 9, S10 in Figure 10).

[0061] Furthermore, after the gear shift is completed, if the gear shift pedal 17 is operated so that the opening is below a specified value (T7 in Figure 9, S11 in Figure 10: Yes), the gear shift control unit 70 activates the adjustment operation of the continuously variable transmission 30 by the gear shift pedal 17 and automatically controls the brake drive member 65 to release the brake 44 and put it into a non-operating state (S12 in Figure 10). Alternatively, after activating the adjustment operation of the continuously variable transmission 30 by the gear shift pedal 17, the gear shift control unit 70 may set the release condition for the brake 44 as the amount of acceleration operation of the gear shift pedal 17 or the amount of operation of the HMT operation actuator such as the continuously variable transmission drive member 33 being above a predetermined threshold.

[0062] The gear shift control unit 70 allows the step-shift drive of the step-shift transmission 40, and then allows the running section to start, with the completion of the gear shift drive of the step-shift transmission 40 as the starting condition (T8 in Figure 9). Here, the completion of the gear shift drive of the step-shift transmission 40 means when the gear shift drive of the main transmission member 45 to the target position (reverse position) is completed. For example, this can be when the shift of the shifter 45b of the main transmission member 45, which is a ball clutch, to the target shift position (reverse shift position) is completed, fixing the ball 45a corresponding to the target gear (main transmission shaft reverse gear 67) to the main transmission shaft 41, thereby fixing the target gear (main transmission shaft reverse gear 67) to the main transmission shaft 41 and enabling power transmission from the main transmission shaft 41 to the target gear (reverse gear shaft 43).

[0063] Alternatively, as another example, the completion of the switching drive of the stepped transmission 40 may also be defined as the completion of the switching of the main transmission drive member 52 to the target switching position (reverse switching position) in order to drive the main transmission member 45 to the target position (reverse position) by the main transmission drive member 52 (T6' in Figure 11). Figure 11 is a timing chart showing an example of operation in which the stepped transmission 40 shifts gears in the rice transplanter 1, similar to Figure 9, and only shows the operation example of the stepped transmission 40. In this case, the switching drive of the main transmission member 45 to the target position (reverse position) may not be completed due to deflection of the operating rod constituting the actuator of the main transmission drive member 52, for example, the shifter 45b of the main transmission member 45, which is a ball clutch, may not have completed shifting to the target shift position (reverse shift position).

[0064] Alternatively, the completion of the shifting drive of the stepped transmission 40 may be defined as operating the main transmission drive member 52 more than the normal target shifting position (reverse shifting position) in order to smoothly drive the main transmission member 45 to the target position (reverse shifting position), and then returning the main transmission drive member 52 to the normal target shifting position (reverse shifting position) after the driving of the main transmission member 45 to the target position (reverse shifting position) is completed, in which case the main transmission drive member 52 may stop at the normal target shifting position (reverse shifting position) on the first attempt (T6'' in Figure 12). Figure 12 is a timing chart showing an example of operation in which the stepped transmission 40 shifts speed in the rice transplanter 1, similar to Figure 9, and only the operation example of the stepped transmission 40 is shown.

[0065] Furthermore, the gear shift control unit 70 may add other conditions as starting conditions for the running gear, in addition to the completion of the switching drive of the stepped transmission 40. For example, the gear shift control unit 70 may add the stopping of the running gear as another starting condition. Alternatively, the gear shift control unit 70 may add further deceleration from a predetermined speed threshold as another starting condition.

[0066] As described above, according to this embodiment, the rice transplanter 1, which is an example of a work vehicle, includes a stepped transmission 40 that changes the speed of the power transmitted from the engine 11 (power source) to the running section, which is the front wheel 13 and rear wheel 14, by switching to one of a plurality of gear positions, a gear lever 18 (stepped transmission operation unit) that receives switching operations of the stepped transmission 40, and a gear control unit 70 that controls the switching drive of the stepped transmission 40 based on the detection result of the switching operation by the gear lever 18. The gear control unit 70 starts deceleration of the running section in response to the switching operation by the gear lever 18, and waits for the switching drive of the stepped transmission 40 corresponding to the switching operation by the gear lever 18 until the driving speed of the running section falls below a predetermined speed threshold, while allowing the switching drive of the stepped transmission 40 corresponding to the switching operation by the gear lever 18 when the driving speed of the running section falls below a predetermined speed threshold as a switching condition.

[0067] As a result, even when the stepped transmission 40 of the rice transplanter 1 is switched, it can reduce speed before switching and drive, thereby suppressing damage to the drive system and sudden acceleration and deceleration, and improving safety during stepped transmission.

[0068] Furthermore, according to this embodiment, in the rice transplanter 1, the speed control unit 70 allows the switching drive of the stepped transmission 40, and then, with the completion of the switching drive of the stepped transmission 40 as the starting condition, allows the running unit to start.

[0069] As a result, the rice transplanter 1 can safely start moving when the stepped transmission 40 is shifted.

[0070] Furthermore, according to this embodiment, in the rice transplanter 1, the speed control unit 70 sets the speed threshold according to the current gear position and / or target gear position of the stepped transmission 40.

[0071] As a result, in the rice transplanter 1, the drive speed at which the stepped transmission 40 can smoothly shift speeds varies depending on the shift position. However, the stepped transmission 40 can shorten the shift time by starting the switching drive at the optimal timing for each shift position. In addition, the stepped transmission 40 can improve operability during stepped shifting by making the speed threshold corresponding to the drive speed different depending on the shift position.

[0072] For example, in this embodiment, the stepped transmission 40 has a neutral position as a gear shift position in which power is not transmitted to the running gear, and when a switching operation is performed by the gear shift lever 18 to switch the stepped transmission 40 from the current gear shift position to the target gear shift position via the neutral position, the gear shift control unit 70 allows the stepped transmission 40 to switch from the current gear shift position to the neutral position, with the switching condition being that the driving speed of the running gear becomes less than or equal to a first speed threshold V1, and allows the stepped transmission 40 to switch from the neutral position to the target gear shift position, with the switching condition being that the driving speed of the running gear becomes less than or equal to a second speed threshold V2 which is smaller than the first speed threshold V1.

[0073] In the rice transplanter 1, when the stepped transmission 40 is switched, if the drive speed is not approximately zero, problems may occur due to the connection of the main transmission member 45 or the meshing of other gears. However, when switching to the neutral position, such problems do not occur. Therefore, according to this embodiment, by switching to the neutral position before the drive speed becomes zero, the shift time can be shortened. Furthermore, when switching to a target shift position via the neutral position, by switching to the neutral position before the drive speed becomes zero and approaching the target shift position, it is possible to switch to the target shift position before the drive speed becomes zero, further shortening the shift time.

[0074] Furthermore, according to this embodiment, the rice transplanter 1 further includes a continuously variable transmission 30 that adjusts the power transmitted to the travel unit, and a gear shift pedal 17 (continuously variable transmission operation unit) that receives adjustment operations for the continuously variable transmission 30. The gear shift control unit 70 decelerates the power transmitted to the travel unit by the continuously variable transmission 30 based on the detection result of the switching operation by the gear shift lever 18.

[0075] As a result, in the rice transplanter 1, the continuously variable transmission 30 reduces the speed to a speed threshold at which the stepped transmission 40 can be switched, thereby reducing the operator's burden and improving operability when using stepped transmissions.

[0076] Furthermore, according to this embodiment, the rice transplanter 1 further includes a brake 44 for braking the travel section and a brake drive member 65 for operating the brake 44. After a switching operation is performed by the shift lever 18, the gear shift control unit 70 uses the brake drive member 65 to operate the brake 44 when the driving speed of the travel section becomes less than or equal to a predetermined braking speed V3 as the braking condition.

[0077] Furthermore, the gear shift control unit 70 allows the stepped transmission 40 to switch gears, with the brake 44 being activated by the brake drive member 65 as the switching condition.

[0078] As a result, the rice transplanter 1 can suppress the vehicle from starting to move the moment it shifts to the target gear position, specifically, the moment it shifts from the neutral position to the target gear position on a slope, thereby improving safety when using stepped gears.

[0079] Furthermore, according to this embodiment, in the rice transplanter 1, the gear shift control unit 70 disables the adjustment operation by the gear shift pedal 17 in response to a switching operation by the gear shift lever 18, and after the switching drive of the stepped gear shift device 40 is completed, it enables the adjustment operation by the gear shift pedal 17 in response to a predetermined operation of the gear shift pedal 17.

[0080] As a result, in the rice transplanter 1, even when the gear shift pedal 17 is operated and the gear shift drive of the stepped transmission 40 is completed, the gear shift pedal 17 is in a deactivated state, which suppresses the sudden start of the running section and improves safety during stepped gear shifting. In addition, since a predetermined operation of the gear shift pedal 17 is required when the gear shift drive of the stepped transmission 40 is completed, the running section can be started according to the operator's intention, improving operability during stepped gear shifting.

[0081] In the above-described embodiment, the stepped transmission 40 of the rice transplanter 1 was shown to have multiple gear positions, namely a forward position, a neutral position, and a reverse position. However, the present invention is not limited to this example. As another example, the stepped transmission 40 may be configured to have multiple gear positions, namely a low-speed position, a medium-speed position, a high-speed position, and so on.

[0082] In the embodiments described above, an example was explained in which the work vehicle of the present invention is composed of a rice transplanter 1. However, the present invention is not limited to this example, and the work vehicle of the present invention may be composed of other agricultural machinery such as tractors, combine harvesters, and lawnmowers, or other work vehicles other than agricultural machinery.

[0083] Furthermore, the present invention may be modified as appropriate, provided that it does not contradict the gist or idea of ​​the invention as can be inferred from the claims and the specification as a whole, and work vehicles with such modifications are also included in the technical concept of the present invention.

[0084] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0085] <Note 1> A stepped transmission that switches between multiple gear positions to change the speed of power transmitted from the power source to the drive unit, A stepped gear shift operation unit that receives the switching operation of the stepped gear shift device, The system includes a control unit that controls the switching drive of the stepped transmission based on the detection result of the switching operation by the stepped transmission operation unit, The control unit starts decelerating the running gear in response to a switching operation by the stepped gear shift operation unit, and waits for the stepped gear shift device to switch in response to the switching operation by the stepped gear shift operation unit until the driving speed of the running gear falls below a predetermined speed threshold, while allowing the stepped gear shift device to switch in response to the switching operation by the stepped gear shift operation unit, with the driving speed of the running gear falling below the predetermined speed threshold as the switching condition.

[0086] <Note 2> The work vehicle according to Appendix 1, characterized in that the control unit allows the switching drive of the stepped transmission, and then allows the starting of the running section with the completion of the switching drive of the stepped transmission as the starting condition.

[0087] <Note 3> The work vehicle according to Appendix 1 or 2, characterized in that the control unit sets the speed threshold according to the current gear position and / or target gear position of the stepped transmission.

[0088] <Note 4> The aforementioned stepped transmission has a neutral position as the gear shift position, which is a state in which power is not transmitted to the running gear. The control unit, when a switching operation is performed by the stepped gear shift operation unit to switch the stepped gear shift from the current gear position to the target gear position via the neutral position, allows the stepped gear shift to be driven from the current gear position to the neutral position, with the switching condition being that the drive speed of the travel unit becomes less than or equal to a first speed threshold, and allows the stepped gear shift to be driven from the neutral position to the target gear position, as described in Appendix 3.

[0089] <Note 5> A continuously variable transmission that adjusts the power transmitted to the aforementioned running section, The system further comprises a stepless transmission control unit that receives adjustment operations for the aforementioned stepless transmission, The work vehicle according to any one of the appendices 1 to 4, characterized in that the control unit reduces the power transmitted to the running unit by the continuously variable transmission based on the detection result of the switching operation by the stepped speed shift operation unit.

[0090] <Note 6> A brake for braking the aforementioned running section, The system further comprises a brake drive member for activating the aforementioned brake, The work vehicle according to any one of the appendices 1 to 5, characterized in that the control unit activates the brake using the brake drive member after a switching operation by the stepped speed shifting operation unit, with the driving speed of the travel unit being below a predetermined braking speed as the braking condition.

[0091] <Note 7> The work vehicle according to Appendix 6, characterized in that the control unit allows the switching drive of the stepped transmission device with the brake being operated by the brake drive member as the switching condition.

[0092] <Note 8> The work vehicle according to Appendix 5, characterized in that the control unit disables the adjustment operation by the continuously variable transmission control unit in response to a switching operation by the stepped transmission control unit, and after the switching drive of the stepped transmission is completed, enables the adjustment operation by the continuously variable transmission control unit in response to a predetermined operation of the continuously variable transmission control unit. [Explanation of Symbols]

[0093] 1. Rice transplanter (work vehicle) 2. Body 3 Planting area 4. Control device 11. Engine (power source) 12 Transmission 13 Front wheels (running section) 14. Rear wheels (running section) 17. Gear shift pedal (continuously variable speed control unit) 18. Gear shift lever (stepped gear shift operation part) 30 Continuously Variable Transmission 33 Continuously Variable Speed ​​Drive Member 40-speed transmission 44 Brake 45 Main transmission component 47 Sub-transmission component 52 Main transmission drive member 53 Sub-transmission drive member 65 Brake drive member 70. Gear shift control unit (control unit)

Claims

1. A stepped transmission that switches between multiple gear positions to change the speed of power transmitted from the power source to the drive unit, A stepped gear shift operation unit that receives the switching operation of the stepped gear shift device, The system includes a control unit that controls the switching drive of the stepped transmission based on the detection result of the switching operation by the stepped transmission operation unit, The control unit starts decelerating the travel unit in response to the switching operation by the stepped gear shift operation unit, and waits for the stepped gear shift device to switch in response to the switching operation by the stepped gear shift operation unit until the drive speed of the travel unit falls below a predetermined speed threshold, while allowing the stepped gear shift device to switch in response to the switching operation by the stepped gear shift operation unit when the drive speed of the travel unit falls below the predetermined speed threshold as a switching condition. A brake for braking the aforementioned running section, The system further comprises a brake drive member for activating the aforementioned brake, The control unit is characterized in that, after a switching operation is performed by the stepped speed shifting unit, the brake is activated by the brake drive member when the driving speed of the travel unit becomes less than or equal to a predetermined braking speed as a braking condition.

2. The work vehicle according to claim 1, characterized in that the control unit allows the switching drive of the stepped transmission and then allows the starting of the running section with the completion of the switching drive of the stepped transmission as the starting condition.

3. The work vehicle according to claim 1 or 2, characterized in that the control unit sets the speed threshold according to the current gear position and / or target gear position of the stepped transmission.

4. The aforementioned stepped transmission has a neutral position as the gear shift position, which is a state in which power is not transmitted to the running gear. The control unit, when a switching operation is performed by the stepped gear shift operation unit to switch the stepped gear shift from the current gear position to the target gear position via the neutral position, allows the stepped gear shift to be driven from the current gear position to the neutral position, with the switching condition being that the drive speed of the travel unit becomes less than or equal to a first speed threshold, and allows the stepped gear shift to be driven from the neutral position to the target gear position, as described in claim 3.

5. A continuously variable transmission that adjusts the power transmitted to the aforementioned running section, The system further comprises a stepless transmission control unit that receives adjustment operations for the aforementioned stepless transmission, The work vehicle according to claim 1, characterized in that the control unit reduces the power transmitted to the running unit by the continuously variable transmission based on the detection result of the switching operation by the stepped speed shift operation unit.

6. The work vehicle according to claim 1, characterized in that the control unit allows the switching drive of the stepped transmission device with the brake being operated by the brake drive member as the switching condition.

7. The work vehicle according to claim 5, characterized in that the control unit disables the adjustment operation by the continuously variable transmission control unit in response to a switching operation by the stepped transmission control unit, and after the switching drive of the stepped transmission is completed, enables the adjustment operation by the continuously variable transmission control unit in response to a predetermined operation of the continuously variable transmission control unit.

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