Work vehicles

Abstract

To provide a work vehicle capable of performing travel gear shift operation of a travel machine body using a gear shift operation tool more smoothly and with high operability in the work vehicle comprising a control unit for controlling a stepless gear shift device.SOLUTION: A work vehicle comprises: a hydraulic gear shift device; a gear shift operation tool; operation position detection means for detecting an operation position of the gear shift operation tool; an actuator for operating a trunnion shaft of the hydraulic gear shift device; and a control unit. The gear shift operation tool is configured to perform swing operations in different two directions from a neutral position and configured to automatically return to the neutral position when the swing operation from the neutral position is cancelled. The control unit performs a stepless gear shift in accordance with the operation position of the gear shift operation tool in a case where the gear shift operation tool is operated to a forward side or a backward side for a predetermined time or longer and, on the other hand, performs stepped gear shift in accordance with an operation direction of the gear shift operation tool in a case where the gear shift operation tool is operated to the forward side or the backward side within the predetermined time.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a work vehicle equipped with a control unit that controls the gear shifting operation of a traveling machine body. [Background technology]

[0002] A traveling machine body having a control unit for an operator to operate the traveling machine body, and a hydraulic transmission for changing the traveling power of the traveling machine body. (Continuously variable transmission) The work vehicle described in Patent Document 1 is known in the art and includes a gear change device provided on the control unit for changing gears in the hydraulic transmission, an operating position detection means for detecting the operating position of the gear change device, an actuator for changing gears in the hydraulic transmission, and a control unit for shifting the hydraulic transmission to a forward state, a neutral state, or a reverse state depending on the operating position of the gear change device.

[0003] According to the work vehicle of the above document, the continuously variable transmission can be operated by an electric operation method controlled via the electric actuator, and a gear ratio adjustment means is provided that adjusts the gear ratio operated in accordance with the operating position of the transmission operating device, making it possible to easily adjust the amount of gear change in accordance with the amount of operation of the transmission operating device. However, compared to when the continuously variable transmission is manually operated through a mechanical linkage, the operation method and operability are roughly the same and cannot be said to have been improved, and there is an issue of increased costs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3635823 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention uses an actuator Hydraulic Transmission In a work vehicle equipped with a control unit for controlling Gear shifting device by Running vehicleThe present invention aims to provide a work vehicle that allows smoother and more user-friendly gear shifting operations while traveling. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a vehicle having a traveling machine body having a control section where an operator operates the vehicle for traveling, a hydraulic speed change device for changing the speed of the traveling power of the traveling machine body, a speed change operating device provided on the control section for operating the hydraulic speed change device, operating position detection means for detecting the operating position of the speed change operating device, an actuator for operating a trunnion shaft of the hydraulic speed change device, and a control section for switching the hydraulic speed change device to a forward state, a neutral state, or a reverse state according to the operating position of the speed change operating device, and the speed change operating device is configured to be swingable in two different directions from a neutral position, and is configured to be capable of being released from the swinging operation from the neutral position. the control unit is configured to shift the hydraulic transmission to the forward side when the gearshift operating device is swung to one side from the neutral position, and to shift the hydraulic transmission to the reverse side when the gearshift operating device is swung to the other side from the neutral position; and the control unit is configured to perform infinitely variable gear shifting in accordance with the operating position of the gearshift operating device when the gearshift operating device is operated to the forward or reverse side for a predetermined period of time or more, and to perform stepped gear shifting in accordance with the operating direction of the gearshift operating device when the operation of the gearshift operating device to the forward or reverse side is within a predetermined period of time.

[0007] Secondly, the control unit is characterized in that, when the speed change is performed continuously by the speed change operating device, the control unit is configured to increase or decrease the operating speed of the trunnion axis operated via the actuator in accordance with the amount of operation of the speed change operating device from the neutral position.

[0008] Thirdly, when the trunnion shaft is operated to a neutral state by the stepless speed change operation of the speed change operation tool, the control unit Hydraulic Transmission and maintains the neutral state of the gear shifter via the gear shift operating device. Hydraulic TransmissionThe control unit is configured to restrict the gear shift operation by the gear shift operating device, and when the gear shift operation by the gear shift operating device is restricted, the control unit is configured to release the restriction on the gear shift operation by the gear shift operating device by returning the gear shift operating device to a neutral position.

[0009] Fourthly, when the speed change is performed by the speed change device, the control unit adjusts the speed change amount in accordance with the amount of operation of the speed change device. Hydraulic Transmission and a low-speed mode in which the amount of gear shift that can be operated by the gear shift operating tool is smaller than that in the normal mode.

[0010] Fifthly, the control unit is configured to slow down the operating speed of the trunnion shaft operated via the actuator as the amount of operation of the speed change operating device from the neutral position decreases. Effect of the Invention

[0011] The speed change operating device is configured to automatically return to a neutral position, and the control unit is configured to automatically return the speed change operating device to a neutral position when the speed change operating device is operated to the forward or reverse side for a predetermined period of time or more according to the operating direction. Hydraulic Transmission On the other hand, when the speed change operating tool is operated to the forward or reverse side within a predetermined time, the Hydraulic Transmission By configuring the gear shifter to have a stepped speed change, the gear shifter can be operated by a single gear shifter. Hydraulic Transmission Since it is possible to operate the vehicle forward and backward with stepless acceleration and deceleration, and forward and backward with stepped acceleration and deceleration, operability is further improved.

[0012] In addition, when the speed change device is used to change the speed steplessly, the operating speed of the trunnion shaft operated via the actuator is increased or decreased in accordance with the amount of operation of the speed change device from the neutral position. Hydraulic Transmission The user can intuitively control the acceleration / deceleration of the traveling machine body with a similar operational feel to that when operating the vehicle.

[0013] When the trunnion shaft is operated to a neutral state by the stepless speed change operation of the speed change operating tool, the control unit Hydraulic Transmission and maintains the neutral state of the gear shifter via the gear shift operating device. Hydraulic Transmission and the control unit is configured so that, when the gear shift operation by the gear shift operating device is restricted, the restriction on the gear shift operation by the gear shift operating device is released by returning the gear shift operating device to a neutral position. According to this, when the traveling vehicle body is stopped by operation of the gear shift operating device, the gear shift operating device will stop even if it has been operated from the neutral position to the forward or reverse side, and the traveling vehicle body cannot be moved forward or backward until the gear shift operating device is returned to the neutral state, thereby further improving safety.

[0014] The control unit controls the speed changer in response to an amount of operation of the speed changer. Hydraulic Transmission By configuring the vehicle to be switchable between a normal mode in which the gear is changed at a high speed, and a low-speed mode in which the amount of gear change that can be operated by the gear change operating device is smaller than in the normal mode, it becomes possible to operate the gear change operating device to increase or decrease speed at a lower speed, making it possible to more smoothly and easily perform work that requires speed control at low speeds, such as when driving for work or when stacking or unloading luggage.

[0015] Furthermore, if the control unit is configured to slow down the operating speed of the trunnion axis operated via the actuator the smaller the amount of operation of the speed change operating device from the neutral position, the speed of the traveling body can be adjusted more finely, thereby improving operability. [Brief description of the drawings]

[0016] [Figure 1] 1 is an overall plan view of a riding rice transplanter (transplanter) to which a work vehicle of the present invention is applied. [Diagram 2] 1 is an overall side view of a riding rice transplanter (transplanter) to which the work vehicle of the present invention is applied. [Diagram 3]FIG. 2 is a side view of a main portion showing the steering mechanism and the HST control mechanism. [Figure 4] FIG. 2 is a front perspective view of a main portion showing the steering mechanism and the HST control mechanism. [Diagram 5] FIG. 2 is a rear perspective view of a main portion showing the steering mechanism and the HST control mechanism. [Figure 6] FIG. 2 is an enlarged view of a main part showing an operating arm for operating the traveling HST. [Figure 7] 4A and 4B are side views of the main part of the brake operation linkage mechanism before and during operation of the brake operating device. [Figure 8] FIG. 2 is a block diagram of a control unit. [Figure 9] FIG. 1A is a diagram showing the vehicle speed when the shift lever is operated for stepless shifting, FIG. 1B is a diagram showing the vehicle speed when the shift lever is operated for stepped shifting, and FIG. 1C is a diagram showing the difference in vehicle speed between normal mode and low-speed mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1 and 2 are an overall side view and an overall plan view of a riding rice transplanter (transplanter) to which the work vehicle of the present invention is applied. This riding rice transplanter is equipped with a traveling body 3 supported by a pair of left and right front wheels 1, 1 and rear wheels 2, 2, and a planting work machine 6 connected to the rear of the traveling body 3 via a lifting link 4 so as to be freely raised and lowered.

[0018] The vehicle frame 8 that supports the traveling vehicle body includes an engine (not shown) surrounded by a bonnet 9 at the front, and a traveling HST ( hydraulic transmission, The vehicle is equipped with a hydraulic continuously variable transmission (hydraulic transmission) 10 and a transmission case 11 to which the power output from the traveling HST 10 is input, and a control section 7 is provided at the rear of the engine where an operator (worker) sits and performs steering operations, etc.

[0019] The control section 7 is arranged with a seat 12 for an operator to sit on, a steering handle 13 for steering the traveling body 3 (front wheels 1) via a steering mechanism 20 described later, a main shift lever (shift operating device, forward / reverse switch lever) 14 provided on either the left or right side of the steering handle 13 and operated to swing at least back and forth, an auxiliary shift lever 16 for operating the gear shift of the traveling body 3, a floor step 17 below the steering handle 13, and a brake pedal (manual operating device) 18 provided in front of the floor step 17 so as to be stepped on and for operating the brakes (braking) of the traveling body 3.

[0020] The main speed change lever 14 is provided with a switch operation device 14a arranged so that the operator can push the switch operation device 14a while holding the switch operation device 14a at the upper end of the grip portion. The switch operation device 14a is a changeover switch (changeover operation device) that changes the speed of the traveling machine body 3 to a low speed mode, which is operated by the main speed change lever 14, and is reduced. This will be described in detail later.

[0021] In addition, the main shift lever 14 is configured to be able to swing back and forth from a basic position (neutral position) that is slightly tilted forward, and is configured to automatically return to the neutral position when the back and forth swing operation of the main shift lever is released (see Figure 3, etc.).

[0022] The main speed change lever 14 is configured so that its swing operation position in the front-rear direction can be detected by an operation position detection potentiometer (operation position detection means, operation position detection sensor) 46. The main speed change lever 14 is configured so that the traveling machine body 3 can be switched between a forward state, a stopped state, and a reverse state by operating an HST control mechanism 30 that controls the traveling HST 10 (a trunnion shaft 35 that changes the speed) via a control unit 50 described later. The specific configuration of the HST control mechanism 30 will be described later.

[0023] Specifically, the control unit 50 is configured to execute HST control such that when the main shift lever 14 is operated to the neutral position, the traveling HST 10 is switched to a neutral state, when the main shift lever 14 is operated to a forward position swung forward from the neutral position, the traveling HST 10 is switched to a forward state in which the speed is shifted forward in accordance with the amount of operation when the main shift lever 14 is operated to a reverse position swung backward from the neutral position, the traveling HST 10 is switched to a reverse state in which the speed is shifted backward in accordance with the amount of operation. The HST control will be described later.

[0024] The brake pedal 18 has a step portion 18a that the operator steps on, a rod-shaped extension portion 18b that extends downward and rearward in a U-shape from the step portion 18a, and a pivot portion 18c that pivots the rear end of the extension portion 18b on a left-right support shaft 15 that is disposed below the floor step, and the step portion 18a is biased to an initial position where it is swung forward (see FIG. 5, etc.). The brake pedal 18 (the pivot portion 18c) is provided with a brake operation linkage mechanism 40 that switches the traveling HST 10 to a neutral state (neutral state) via the HST control mechanism 30. This will be described in detail later.

[0025] The planting work machine 6 has a seedling carrier 22 on which seedlings to be planted in the field are placed, and a planting unit 23 that carries out the planting work of the seedlings placed on the seedling carrier 22 into the field, and is raised and lowered relative to the running body 3 via the lifting cylinder 4, and power transmitted from the engine is transmitted intermittently via a planting clutch (not shown).

[0026] Next, the steering mechanism and the HST control mechanism will be described with reference to Figures 3 to 6. Figures 3 to 5 are a side view, a front perspective view, and a rear perspective view of the main parts showing the steering mechanism and the HST control mechanism, and Figure 6 is an enlarged view of the main parts showing an operating arm that operates the traveling HST.

[0027] The steering mechanism 20 comprises the steering shaft extending in the vertical direction, the transmission case 11 which is arranged between the left and right front wheels 1, 1 and which has built-in transmission gears for changing the speed of engine power to each component, a pitman arm (not shown) supported on the underside of the transmission case 11 so as to be able to swing freely left and right, a power steering device 32 which is arranged below the steering shaft 19 and on the upper side of the transmission case 11, and a cylindrical steering column 31 through which the steering shaft 19 is inserted, and a support bracket 33 which is formed in a U-shape with an open upper portion is provided on the upper side of the power steering device 32.

[0028] The HST control mechanism 30 includes a support shaft 36 supported so as to penetrate the left and right sides of the support bracket 33 in the left-right direction, a swing arm 37 attached so as to be swingable in the vertical direction around the support shaft 36 and arranged on the outside of the left side of the support bracket 33, an operation arm 38 supported so as to rotate integrally with a trunnion shaft 35 that changes the speed of the traveling HST 10, a vertical operation rod 39 having an upper end connected to the swing arm 37 side and a lower end connected to the operation arm 38 side, a motor 42 installed so as to be able to rotate the support shaft 36 about its axis via a clutch 41 described later, and the control unit 50, and the torque limiter type clutch 41 is provided on the left end side of the support shaft 36 (see Figures 3 to 5, etc.).

[0029] The HST control mechanism 30 is provided with a brake operation linkage mechanism 40 for manually operating the traveling HST 10 via the brake pedal 18, and is configured so that the traveling HST 10 can also be directly operated by manual operation by an operator. A specific configuration of the brake operation linkage mechanism 40 will be described later.

[0030] According to this configuration, the HST control mechanism 30 is configured to rotate the support shaft 36 about its axis by the driving force of the motor 42, to swing the oscillating arm 37 up and down by the axial rotation of the support shaft 36, to move the operating rod 39 up and down by the up and down swinging movement of the oscillating arm 37, and to operate the operating position of the operating arm 38 that operates the trunnion shaft 35 by the up and down movement of the operating rod 39 (see Figures 4 to 6, etc.).

[0031] At this time, an operating arm detection potentiometer 47 that detects the operating position of the operating arm 38 is provided on the side of the operating arm 38, and the control unit 50 is configured to be able to check the gear shifting state of the traveling HST 10 by detecting the operating position of the operating arm 38 (see Figure 6, etc.).

[0032] According to the above-mentioned configuration, the control unit 50 is configured to be able to execute the HST shift control by controlling the drive of the motor 42 based on the forward and backward swing operation of the main shift lever 14 detected by the operation position detection potentiometer 46 and the current shift state of the traveling body 3 (traveling HST 10) detected by the operation arm detection potentiometer 47.

[0033] The clutch 41 is provided on the left end side of the support shaft 36 on the outside of the left side surface of the support bracket 33 so as to rotate integrally with the support shaft 36, and has a drive gear 41A that rotates freely around the support shaft 36 by meshing with the output gear 42a of the motor 42, a torque limiter-type clutch portion 41B that interrupts the transmission of power between the drive gear 41A and the support shaft 36, and an elastic member (biasing member) 41C that biases the clutch portion 41B toward the drive gear 41A (see Figure 3, etc.).

[0034] As a result, the clutch 41 is configured so that when the support shaft 36 (drive gear 41A) rotates with a torque stronger than the driving force of the motor 42 (the biasing force of the elastic member), power transmission between the motor 42 and the support shaft 36 is cut off.

[0035] In other words, the clutch 41 is configured to be able to operate the oscillating arm 37 (operating arm 38) via the support shaft 36 when the motor 42 is driven, while being able to prevent the operating force from being transmitted to the motor 42 when the support shaft 36 (operating arm 37) side is operated with a force (torque) greater than the driving force of the motor 42 via the brake operation linkage mechanism 40.

[0036] More specifically, the motor 42 is disposed on the upstream side of the clutch 41, while on the downstream side of the clutch 41, power is transmitted in the order of the support shaft 36 → the swing arm 37 → the operating rod 39 → the operating arm 38 → the trunnion shaft 35 to link with the traveling HST 10. The brake operation linkage mechanism 40, which will be described later, operates the support shaft 36 by the operating force exerted by depressing the brake pedal 18, thereby operating the trunnion shaft 35 to the neutral state.

[0037] Next, the configuration of the brake operation linkage mechanism will be specifically described with reference to Figures 3 to 7. Figures 7(A) and (B) are side views of the main part of the brake operation linkage mechanism, showing the brake operation linkage mechanism before and during operation of the brake operating tool.

[0038] The brake operation linkage mechanism 40 includes a swing piece 51 provided on the pivot portion 18c of the brake pedal, a linkage rod 52 extending forward from the swing piece 51 and pushed and pulled in the front-rear direction in response to operation of the brake pedal 18, a first linkage arm 53 connected to the front end side of the linkage rod 52 and swinging forward and backward, a second linkage arm 54 swinging up and down in response to swinging operation of the first linkage arm 53, and a linkage arm 55 connecting the first linkage arm and the It comprises a linkage arm support shaft 56 which supports the second linkage arm 54, a diamond-shaped brake operation linkage arm 57 which rotates integrally with the support shaft 36 at the right end side of the support shaft 36, a first linkage member 58 in the vertical direction which links the front end side of the brake operation linkage arm 57 with the second linkage arm 54, and a second linkage member 59 in the vertical direction which links the rear end side of the brake operation linkage arm 57 with the second linkage arm 54 (see Figure 7, etc.).

[0039] The upper end side of the first linking member 58 and the upper end side of the second linking member have through holes 58a, 59a which are long holes extending in the vertical direction, and are connected to the front and rear end sides of the brake operation linking arm 57 via the through holes 58a, 59a, respectively (see Figure 7(A)).

[0040] At this time, when the brake pedal 18 is not depressed (see Figure 7 (A)) and the support shaft 36 is rotated via the motor 42, the brake operation linkage arm 57 is configured to swing within the range of the accommodation holes 58a, 59a.

[0041] On the other hand, when the brake pedal 18 is depressed (see Figure 7 (B)), each of the accommodation holes 58a, 59a is configured to connect in the following order: brake pedal 18 → oscillating piece 51 → linking rod 52 → first linking arm 53 → linking arm support shaft 56 → second linking arm 54 → first linking member 58 → brake operation linking arm 57, thereby enabling the support shaft 36 to rotate in a predetermined direction.

[0042] As a result, the brake operation linkage mechanism 40 (and the HST control mechanism 30) is configured to be able to perform a gear shift operation of the traveling HST 10 to a neutral state by stepping on the brake pedal 18.

[0043] With this configuration, when the brake pedal 18 is depressed, the brake operation linkage mechanism 40 can forcibly operate the traveling HST 10 into a neutral state (stopped state) regardless of the driving state of the motor 42 controlled by the control unit 50, thereby more reliably stopping the traveling body 3.

[0044] Incidentally, when the support shaft 36 (traveling HST 10) is operated via the brake operation linkage mechanism 40 as a result of depression of the brake pedal 18, the clutch 41 can reliably prevent the axial rotation of the support shaft 36 from being transmitted to the motor 42. As a result, when the traveling HST 10 is forcibly changed in speed by the brake operation (manual operation) by the operator, the motor 42 is not forcibly rotated, so it is possible to prevent a situation in which an unnecessary load is applied to the motor 42 and a breakdown occurs.

[0045] Next, the control contents of the HST shift control by the control unit will be described with reference to Figures 8 and 9. Figure 8 is a block diagram of the control unit, Figure 9(A) is a diagram showing the vehicle speed when the shift lever is operated to shift infinitely forward or reverse, to return to the original position, and to decelerate, Figure 9(B) is a diagram showing the vehicle speed when the shift lever is operated to shift infinitely forward or reverse, and Figure 9(C) is a diagram showing the difference in vehicle speed between normal mode and low-speed mode.

[0046] The input side of the control unit 50 is connected to the operation position detection potentiometer 46 which detects the operation position of the main speed change lever 14, a detection potentiometer (operation arm detection potentiometer) 47 which detects the operation position of the operation arm 38 (trunnion shaft 35), and the switch operation device 14a, and the output side of the control unit 50 is connected to the motor 42 (see FIG. 8). The control unit 50 also has a timer and is configured to be able to detect the operation time during which the main speed change lever 14 is swung.

[0047] The operation position detection potentiometer 47 is configured to be able to detect the operation position of the main speed change lever 14, specifically, the operation direction (forward or reverse) of the main speed change lever 14, the operation amount from the neutral position, and the operation speed (angular velocity of the shaft) when the main speed change lever 14 is swung. Also, it is configured to be able to detect the operation time when the main speed change lever 14, which is biased toward the neutral position using the timer or the like, is swung.

[0048] The HST shift control by the control unit 50 is configured to, when a pivoting operation (hereinafter, infinitely variable shift operation) of the main shift lever 14 from the neutral position toward the forward or reverse position for a preset period of time or longer is detected, to infinitely variable shift the traveling HST 10 to the forward or reverse side according to the operating position of the main shift lever 14 (see (1) in FIG. 9(A)), and thereafter, when an operation (return operation) of the main shift lever 14 to return to the neutral position is detected, to maintain the traveling speed at the time when the return operation was detected (see (2) in FIG. 9(A)).

[0049] Specifically, when a stepless speed change operation in the forward direction of the main shift lever 14 is detected and the traveling HST 10 is in a neutral state, the traveling HST 10 (trunnion shaft 35) is shift-controlled so that the traveling body 3 increases (or decreases) speed steplessly in a direction corresponding to the operation direction of the main shift lever 14 and toward a traveling speed corresponding to the operation position (amount of operation from the neutral position) of the main shift lever 14.

[0050] Incidentally, when the main speed change lever 14 is operated to perform a stepless speed change (stepless deceleration operation) in the direction opposite to the traveling direction of the traveling body 3, the traveling HST 10 is steplessly decelerated (see (3) in Figure 9(A)).

[0051] In response to this, when the traveling HST 10 is operated from a forward or reverse state to a neutral state by the above-mentioned stepless deceleration operation and the traveling body 3 is stopped, the control unit 50 is configured to restrict the traveling HST 10 from shifting to the forward or reverse side depending on the operating position of the main shift lever 14, even if the operation of the main shift lever 14 to the forward or reverse position is maintained.

[0052] In this case, the control unit 50 is configured such that, when a return operation of the main shift lever 14 to the neutral position is detected, the state that restricts the main shift lever 14 from shifting the traveling HST 10 from the neutral state to the forward or reverse side is released.

[0053] According to this configuration, when the speed is reduced by the stepless speed change operation of the main speed change lever 14, it is possible to reliably prevent the traveling body 3 from starting to travel in the reverse direction immediately after stopping, thereby improving safety.

[0054] On the other hand, when an operation of swinging the main shift lever 14 back and forth to return it to the neutral position in a time shorter than a predetermined time (hereinafter, referred to as a stepped shift operation) is detected, the HST shift control is configured to shift the traveling HST 10 in a stepped manner according to the direction of operation of the main shift lever 14 (see FIG. 9(B)).

[0055] Specifically, when the traveling HST 10 is in neutral or forward travel and the main shift lever 14 is operated to shift gears in the forward direction (stepped speed increase operation), the traveling HST 10 is accelerated in the forward direction by a preset speed increase amount (see (4) in FIG. 9(B)). Note that when the traveling HST 10 is in reverse travel and the main shift lever 14 is operated to shift gears in the forward direction (stepped speed reduction operation), the traveling HST 10 is decelerated by a preset speed reduction amount (see (5) in FIG. 9(B)).

[0056] Similarly, when the traveling HST 10 is in neutral or reverse and a stepped speed change operation (stepped speed increase operation) of the main shift lever 14 is performed in the reverse direction, the traveling HST 10 is increased in speed by a preset speed increase width in the reverse direction (see (4) in FIG. 9(B)). Note that when the traveling HST 10 is in a forward state and a stepped speed change operation (stepped speed reduction operation) of the main shift lever 14 is performed in the reverse direction, the traveling HST 10 is decelerated by a preset speed reduction width (see (5) in FIG. 9(B)).

[0057] According to this configuration, the single main speed change lever 14 can selectively be used for variable speed operation and stepped speed change operation of the traveling machine body 3 (traveling HST 10), improving operability.

[0058] In addition, the HST shift control is configured such that, when it is detected that the main shift lever 14 has been swung forward to the front end operating position (reverse stop operation) while the traveling body 3 is traveling in reverse, the traveling HST 10 is operated from the reverse state to the neutral state, and, when it is detected that the main shift lever 14 has been swung backward to the rear end operating position (forward stop operation) while the traveling body 3 is traveling forward, the traveling HST 10 is operated from the forward state to the neutral state.

[0059] According to this configuration, regardless of the speed at which the traveling body 3 is traveling, the traveling body 3 can be stopped safely and smoothly with a single simple operation (stopping operation) of the main shift lever 14, thereby improving operability and safety.

[0060] In addition, the HST shift control is configured such that, when the main shift lever 14 is swung forward or backward, the closer the operating position of the main shift lever 14 is from the neutral position, the slower the operating speed of the trunnion shaft 35 operated via the motor 42 becomes.

[0061] With this configuration, fine adjustments to the running speed of the running body 3 can be easily made, and the running body 3 can be easily and smoothly operated to a slow speed at which it can be stopped immediately and maintained at that slow speed, making it easy to perform delicate tasks such as parking a work vehicle in a garage.

[0062] Furthermore, the HST shift control is configured so that it can be switched from normal mode to low-speed mode by pressing the switch operating device 14a, and by rocking the main shift lever 14 back and forth when switched to the low-speed mode, the shift range of the traveling HST 10, which is changed in accordance with the operating position of the main shift lever 14, can be made smaller than in the normal mode (see FIG. 9(C)).

[0063] According to this configuration, by operating the main speed change lever 14 in the low-speed mode, the speed range in which the traveling machine body can be operated is narrowed even with the same operation range, so that the vehicle speed cannot be increased, but fine speed adjustment becomes easier. Therefore, it is possible to prevent the vehicle speed from becoming too fast when traveling for work in a farm field, and it is also possible to adjust the traveling speed for work more smoothly and easily. [Explanation of symbols]

[0064] 2 Running body 7. Control Section 10 Travel HST (hydraulic variable speed transmission, variable speed transmission) 14 Gear shift lever (gear shifting device) 35 Trunnion axis 42 Motor (actuator) 50 Control section

Claims

1. A traveling machine body having a control unit where an operator operates the traveling machine; A hydraulic transmission that changes the speed of the traveling power of the traveling machine body; A gear shifting tool provided in the steering section for performing a gear shifting operation of the hydraulic transmission device; an operating position detection means for detecting an operating position of the gear shift operating device; An actuator for operating a trunnion shaft of the hydraulic transmission; a control unit that switches the hydraulic transmission device to a forward state, a neutral state, or a reverse state according to the operating position of the shift operating tool, the speed change operating device is configured to be pivotable in two different directions from a neutral position, and is configured to automatically return to the neutral position when the pivoting operation from the neutral position is released; the control unit is configured to shift the hydraulic transmission to a forward side when the shift operating device is swung to one side from a neutral position, and to shift the hydraulic transmission to a reverse side when the shift operating device is swung to the other side from a neutral position, The control unit is configured to change the speed steplessly according to the operating position of the gearshift operating device when the gearshift operating device is operated to the forward or reverse side for a predetermined period of time or more, and to change the speed stepwise according to the operating direction of the gearshift operating device when the gearshift operating device is operated to the forward or reverse side for less than a predetermined period of time. Work vehicle.

2. The control unit is configured to increase or decrease the operating speed of the trunnion shaft operated via the actuator in accordance with the amount of operation of the speed change device from a neutral position when the speed change device is used for stepless speed change. A work vehicle according to claim 1.

3. the control unit is configured to maintain a neutral state of the hydraulic transmission device when the trunnion shaft is operated to a neutral state by a stepless speed change operation using the speed change device, and to restrict the speed change operation of the hydraulic transmission device via the speed change device, The control unit is configured such that, when the gear shift operation by the gear shifter is restricted, the restriction on the gear shift operation by the gear shifter is released by returning the gear shifter to a neutral position. A work vehicle according to claim 1 or 2.

4. The control unit is configured to be able to switch between a normal mode in which the hydraulic transmission is changed in accordance with the amount of operation of the shifting device, and a low-speed mode in which the amount of shifting that can be performed by the shifting device is smaller than that in the normal mode, when the shifting device is used for stepless speed change. A work vehicle according to any one of claims 1 to 3.

5. The control unit is configured to slow down the operating speed of the trunnion shaft operated via the actuator as the operation amount of the speed change operating device from the neutral position decreases. A work vehicle according to any one of claims 1 to 4.

Images