Work vehicle

Abstract

To provide a working vehicle capable of traveling safely by making it easy to grasp the state of speed change operation and traveling control.SOLUTION: A work vehicle including a continuously variable transmission 41 that continuously changes a speed based on an operation of a speed change operation tool 18,23 includes a memory switch 70 that causes a control device 100 to store an operation position of the speed change operation tool 18,23, and a high-speed regulation mode S in which a speed change to a high-speed side corresponding to a speed change region faster than the stored operation position is invalidated and the continuously variable transmission 41 is controlled to a speed change position corresponding to the operation position in a speed change region slower than the stored operation position. When the shift position of the shift operation tool 18,23 is in a higher speed region than the set and stored speed at the time of releasing the high-speed regulation mode S, the high-speed regulation is continued until the shift position by the shift operation tool 18,23 returns to the shift at the time of setting the high-speed regulation mode S.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a work vehicle such as an agricultural tractor. [Background technology]

[0002] A known work vehicle is equipped with a continuously variable transmission and an actuator that controls the transmission position of the continuously variable transmission. Once the transmission position is stored, even if the vehicle is subsequently operated to a different transmission position, the actuator will automatically reproduce the stored position by operating a transmission position reproduction switch (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-298099 Summary of the Invention [Problem to be solved by the invention]

[0004] This configuration is convenient because it makes it easy to reproduce the shift position even in a continuously variable transmission, where it is difficult to reproduce the shift position. However, this can cause a discrepancy between the shift operation lever and the actual shift position, which can confuse the driver.

[0005] An object of the present invention is to provide a work vehicle that can be driven safely by making it easy to grasp the state of gear shifting and driving control. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, a first invention provides a work vehicle equipped with a continuously variable transmission (41) that changes speed continuously based on the operation of a speed change operating device (18, 23), the work vehicle being provided with a memory switch (70) that detects the operating position of the speed change operating device (18, 23) and stores the detected operating position in a control device (100), the control device (100) having a high-speed restriction mode (S) that disables shifting to a higher speed corresponding to a speed change region faster than the stored operating position, and in the high-speed restriction mode (S), the continuously variable transmission (41) is controlled to a speed change position corresponding to the operating position in a speed change region slower than the stored operating position. The high-speed restriction mode (S) is released by operating the release switch (71), and if the speed change position of the speed change operating device (18, 23) is in a higher speed range than the speed set and stored in the high-speed restriction mode (S) when the high-speed restriction mode (S) is released, the high-speed restriction is continued until the speed change position of the speed change operating device (18, 23) returns to the speed when the high-speed restriction mode (S) was set. This is a work vehicle characterized by the above. [Effects of the Invention]

[0007] Work vehicle according to the present invention According to the above, it is possible to easily grasp the state of gear shifting and driving control, thereby enabling safe driving. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a left side view of a tractor according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the tractor of FIG. 1. [Figure 3] FIG. 2 is a power transmission diagram of the power transmission device of the same tractor. [Figure 4] 2 is a schematic diagram showing the configuration and operating state of a hydrostatic continuously variable transmission of the tractor. FIG. [Figure 5] FIG. 2 is a block diagram showing a configuration of a part of a control system of the tractor. [Figure 6] FIG. 2 is a schematic explanatory diagram showing the operation of the main shift lever of the tractor. [Figure 7] FIG. 2 is a plan view of the armrest and operation panel of the tractor. [Figure 8] FIG. 8 is a perspective view of FIG. [Figure 9] FIG. 10 is a block diagram of a control system according to another example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] 1 and 2 show a tractor 1, which is an example of a work vehicle according to an embodiment of the present invention.

[0011] This tractor 1 has a running body 2 on which equipment such as an engine 3, a power transmission device 4, a pair of left and right front wheels 5 and rear wheels 6, and a driver's seat 7 is mounted or provided on a support frame or the like (not shown). Of these, the engine 3 is covered by an openable and closable bonnet cover 11. The power transmission device 4 is made up of a hydrostatic continuously variable transmission (HST: Hydraulic Static Transmission) 41, an auxiliary transmission 51, etc., which are arranged in a transmission case 40.

[0012] The tractor 1 is switchable between a four-wheel drive (4WD) system in which rotational power from the engine 3 is transmitted to the left and right front wheels 5 and the left and right rear wheels 6 via a power transmission device 4, etc., to drive the tractor, and a two-wheel drive (2WD) system in which rotational power is transmitted to the left and right rear wheels 6 to drive the tractor, and the tractor runs in either of these drive systems. The running speed (vehicle speed) of the traveling body 2 is detected by a vehicle speed sensor 92 (FIG. 5), and the detected information is sent to the control device 100.

[0013] Furthermore, the tractor 1 can perform desired work by attaching a work implement (not shown), such as a rotary tiller, to the rear of the traveling body 2 via attachment parts such as a lower link 29. A PTO shaft 59 is provided at the rear of the traveling body 2 for outputting the rotational power of the engine 3 to the attached work implement.

[0014] The cockpit 7 has a seat portion 7a where the driver sits and a step floor portion 7b on which the driver places his / her feet when getting in or driving.

[0015] A steering wheel (handle) 12 is provided in front of the driver's seat 7 and is supported by a handle post 20 provided on the support frame of the traveling vehicle body 2, and is used to steer the front wheels 5. A display panel 13 is provided in front of the steering wheel 12 to display information related to steering (traveling speed, operating status, etc.) to the driver.

[0016] A forward / reverse switch lever 14, which is operated to switch between forward and reverse travel, is provided at the upper end of the handle post 20 and the left end below the steering wheel 12. The forward / reverse switch lever 14 has three switch positions: forward position, neutral position, and reverse position. The selected position is detected by a forward / reverse switch position sensor 93 (FIG. 5), and the detected information is sent to the control device 100.

[0017] An accelerator lever 15 for changing the rotation speed of the engine 3 is provided at the other end below the steering wheel 12, above the handle post 20. The accelerator lever 15 is an example of an accelerator operating tool, and is used when driving for work. The accelerator lever 15 is designed to be held in the operated position even if the operator releases the lever, and the amount of operation is detected by an accelerator lever position sensor 74 (FIG. 5), and the detection information is sent to the control device 100.

[0018] On the step floor 7b of the driver's seat 7, to the right of the handlebar post 20, there are provided an accelerator pedal 16, left and right brake pedals 17L, 17R, an HST pedal 18, a clutch pedal 19, etc. The left and right brake pedals 17L, 17R can be switched between a connected state in which the left and right pedals are operated simultaneously by a connecting member, and a disconnected state in which the left and right pedals can be operated individually, and are equipped with a brake pedal connection sensor 81 (Fig. 5) that detects whether the state is connected or disconnected. If operation of the accelerator pedal 16 is detected by the detection value of the accelerator pedal position sensor 95 (Fig. 5) while the brake pedal connection sensor 81 detects the disconnected state, a lamp and / or buzzer is sounded to prevent unsafe driving.

[0019] Accelerator pedal 16 is an example of an accelerator operating tool, and is a step-on pedal that is operated to increase the engine speed and, ultimately, the vehicle speed of traveling vehicle body 2 depending on the amount of depression of accelerator pedal 16. This accelerator pedal 16 is basically used when traveling on the road. The amount of depression of accelerator pedal 16 is detected by accelerator pedal position sensor 95 (FIG. 5), and the detected information is sent to control device 100.

[0020] The HST pedal 18 is an example of a speed change operating tool, and is a seesaw-type pedal that is operated to change the rotation direction and rotation speed (number of revolutions) of the rotational power output from the continuously variable transmission 41 made up of the HST according to the direction and amount of depression of the pedal, and thereby to change the traveling direction (forward or reverse) of the traveling body 2 and adjust the vehicle speed. The HST pedal 18 is mainly used when traveling for work.

[0021] The HST pedal 18 has a stop operation position where the entire pedal can be kept substantially horizontal to bring the vehicle to a stop, a forward operation range where the vehicle speed can be increased or decreased when the entire pedal is depressed so as to tilt the entire pedal forward from the stop operation position, and a reverse operation range where the vehicle speed can be increased or decreased when the entire pedal is depressed so as to tilt the entire pedal backward from the stop operation position. The direction and amount of depression of the HST pedal 18 is detected by an HST pedal position sensor 96 (FIG. 5), and the detected information is sent to the control device 100.

[0022] On the left side of the cockpit 7 in the forward direction, an auxiliary speed change lever 21, a PTO clutch lever 22, a main speed change lever 23, etc. are provided.

[0023] The sub-speed change lever 21 is a lever that is operated to select one of the speed stages (vehicle speed ranges)—for example, low, medium, or high—for the rotational speed of the rotational power transmitted through the sub-transmission device 51. Of these speed stages, the low and medium speeds are vehicle speed ranges suitable for traveling within a field when working in the field, and the high speed is a vehicle speed range suitable for traveling on roads when traveling between fields, etc. The PTO clutch lever 22 is a lever that is operated to connect and disconnect the drive transmission to the PTO shaft 59. The main speed change lever 23 is another example of a speed change operating device, and is a lever that operates the trunnion shaft 47 of the continuously variable transmission 41 to change speeds.

[0024] The selected operating position of the auxiliary shift lever 21 is detected by an auxiliary shift position sensor 94 (FIG. 5), and the detection information is sent to the control device 100. The selected operating position of the main shift lever 23 is detected by a main shift position sensor 99 (FIG. 5), and the detection information is sent to the control device 100.

[0025] As shown in FIG. 2, a position lever 24 for raising and lowering the work equipment, an adjustment panel 25, etc. are provided on the right side of the operator's seat 7 in the forward direction.

[0026] The position lever 24 is an operating lever that adjusts the height of the work implement when it is raised or lowered. The adjustment panel 25 is a portion on which dials, switches, etc. are arranged to set adjustments required for some of the operations of the tractor 1.

[0027] 3, the power transmission device 4 is configured so that the rotational power of the output shaft of the engine 3 is first transmitted to the input shaft 32 of the transmission case 40 via the main clutch 31, where it is accelerated by the speed-up gears 33a and 33b, and then transmitted to the input shaft 42 of the continuously variable transmission 41. The main clutch 31 is actuated depending on whether or not the clutch pedal 19 is depressed.

[0028] The continuously variable transmission 41 employs the above-mentioned HST, and is an integrated device that combines a hydraulic pump 43 and a hydraulic motor 44 .

[0029] The hydraulic pump 43 is a variable displacement hydraulic pump that operates using the rotational power of the engine 3 input through the input shaft 42, and adjusts the discharge state (direction and flow rate (including zero)) of the hydraulic oil sent to the hydraulic motor 44 by changing the tilt angle of a swash plate 45 inside the pump. The hydraulic motor 44 is, for example, a fixed displacement hydraulic motor, and rotates the motor output shaft 44a in a predetermined rotation direction and at a predetermined rotation speed (number of revolutions) depending on the state of the hydraulic oil discharged from the hydraulic pump 43.

[0030] In the power transmission device 4, as shown in FIG. 3, the rotational power of the motor output shaft 44a of the hydraulic motor 44 in the continuously variable transmission 41 passes through the sub-transmission device 51, is output through the drive output shaft 34, and is then transmitted to the left and right rear wheels 6 via the rear wheel differential gear device 35.

[0031] Furthermore, in the power transmission device 4, when the drive switching device 36 including the connecting gear is switched to the four-wheel drive side, the rotational power output from the auxiliary transmission 51 through the drive output shaft 34 is transmitted to the front wheel relay shaft 37 via the drive switching device 36, and then transmitted to the left and right front wheels 5 via the front wheel speed increasing device 38 and the front wheel differential gear device 39. The front wheels 5 receive rotational power that is faster than the rear wheels 6 only when the front wheel speed increasing device 38 is activated to increase the speed, but otherwise receive rotational power at the same rotational speed as the rear wheels 6.

[0032] 3, the power transmission device 4 is provided with a pump output shaft 43a that rotates in the same manner as the input shaft 42 on the hydraulic pump 43 in the continuously variable transmission 41. As a result, in the power transmission device 4, the rotational power of the pump output shaft 43a is transmitted to a PTO intermediate shaft 57 via a PTO forward / reverse clutch 56, and then transmitted to a PTO shaft 59 via a PTO transmission device 58.

[0033] In the continuously variable transmission 41, the swash plate 45 of the hydraulic pump 43 can be switched to any one of a forward output position, a neutral position, and a reverse output position.

[0034] When the swash plate 45 is switched to the forward output position, the continuously variable transmission 41 outputs power from the motor output shaft 44a to rotate the hydraulic motor 44 in the forward direction at a rotational speed corresponding to the tilt angle, and when the swash plate 45 is switched to the reverse output position, the hydraulic motor 44 outputs power from the motor output shaft 44a to rotate the hydraulic motor 44 in the reverse direction at a rotational speed corresponding to the tilt angle. On the other hand, when the swash plate 45 is switched to the neutral position, the continuously variable transmission 41 does not rotate the motor output shaft 44a and does not output power.

[0035] 4, the continuously variable transmission 41 has a trunnion shaft 47 that rotates to adjust the tilt angle of the swash plate 45 in the hydraulic pump 43. The trunnion shaft 47 is rotated via a trunnion arm 48 that moves when a shaft rotating mechanism 60 is operated.

[0036] The shaft rotation mechanism 60 has a hydraulic cylinder mechanism 61 that serves as a drive source, and a link mechanism 65 that transmits the power of the hydraulic cylinder mechanism 61 to the trunnion arm 48 .

[0037] The hydraulic cylinder mechanism 61 is composed of a double-acting hydraulic cylinder 62 and a control valve 63 that operates the hydraulic cylinder 62.

[0038] The link mechanism 65 is composed of a first oscillating arm 67 having one end connected to the tip of the piston rod 62a of the hydraulic cylinder 62 in the hydraulic cylinder mechanism 61 and rotatably supported on a first fixed shaft 66a, a second oscillating arm 68 having one end connected to the rear end of the trunnion arm 48 and rotatably supported on a second fixed shaft 66b, and a connecting arm 69 that rotatably connects the other end of the first oscillating arm 67 and the other end of the second oscillating arm 68.

[0039] The control valve 63 supplies hydraulic oil from a hydraulic pump for the cylinder (not shown) to one end and the other end of the double-acting cylinder portion 62b at the required timing, thereby extending or retracting the piston rod 62a. The control valve 63 is an electromagnetic hydraulic proportional valve equipped with a pair of solenoids 63a, 63b that control the hydraulic oil supply operation, with one solenoid 63a operating for extension and the other solenoid 63b operating for retraction. Reference numeral 64 in Figure 4 denotes oil supply pipes connecting the control valve 63 to one end and the other end of the cylinder portion 62b, respectively.

[0040] In this shaft rotating mechanism 60, when the piston rod 61a of the hydraulic cylinder mechanism 61 is extended in the direction indicated by arrow D1 from a position corresponding to the neutral position shown in Figure 4 by the operation of the control valve 63 to supply hydraulic oil, the force of the extending piston rod 61a is transmitted to the trunnion arm 48 via the link mechanism 62, and the trunnion arm 48 at this time operates to rotate the trunnion shaft 47 in the direction indicated by arrow E1. In this case, the swash plate 45 of the hydraulic pump 43 is moved so as to tilt toward the forward output position.

[0041] Furthermore, when the piston rod 61a of the hydraulic cylinder mechanism 61 is retracted in the direction indicated by arrow D2 from a position corresponding to the neutral position by the operation of the control valve 63 to supply hydraulic oil, the force of the retracting piston rod 61a is transmitted to the trunnion arm 48 via the link mechanism 62, and the trunnion arm 48 at this time operates to rotate the trunnion shaft 47 in the direction indicated by arrow E2. In this case, the swash plate 45 of the hydraulic pump 43 is moved so as to tilt toward the reverse drive output position.

[0042] Furthermore, as shown in FIG. 4, the continuously variable transmission 41 is provided with a neutral holding mechanism 49 that holds the trunnion shaft 47 that rotates the swash plate 45 and the trunnion arm 48 in a neutral position.

[0043] The neutral holding mechanism 49 has a cam plate 49a that rotates integrally with the trunnion shaft 47 as a support shaft and is configured to return to a neutral position, and a roller 49b that is elastically biased and pressed against a recessed peripheral cam portion of the cam plate 49a. One end of the trunnion shaft 47 in this neutral holding mechanism 49 is rotatably connected to a part of the cam plate 49a.

[0044] In the continuously variable transmission 41, when the shaft rotation mechanism 60 is not operating, the neutral holding mechanism 49 holds the trunnion arm 48 in a neutral position (see FIG. 4), thereby returning the swash plate 45 to the neutral position. The rotation angle of the trunnion shaft 47 is detected by a trunnion shaft angle sensor 97 (FIG. 6), which confirms the movement of a portion of the trunnion arm 48, and the detection information is sent to the control device 100.

[0045] In the continuously variable transmission 41, when the operation amount of the transmission operating device, i.e., the main shift lever 23, is detected by the main shift position sensor 99, or the depression direction and amount of the HST pedal 18 is detected by the HST pedal position sensor 96, the control device 100 controls the drive current values ​​supplied to the solenoids 63a, 63b of the control valve 63 in the shaft turning mechanism 60 in accordance with the detection values ​​of the sensors 99, 96. As a result, in the continuously variable transmission 41, the trunnion shaft 47 is turned in the required direction by a required angle according to the depression amount via the trunnion arm 48. As a result, in the continuously variable transmission 41, the inclination angle of the swash plate 45 in the hydraulic pump 43 is changed arbitrarily in conjunction with the rotation of the trunnion shaft 47, thereby adjusting the direction and flow rate of the hydraulic oil discharged from the hydraulic pump 43 to the hydraulic motor 44, and rotational power that rotates in the required direction through the motor output shaft 44a and is continuously changed to the required rotational speed (number of revolutions) is output from the hydraulic motor 44.

[0046] A memory switch 70 is provided on the operation panel 25. When this memory switch 70 is turned ON, the ON signal and the detection value of the main speed change lever position sensor 99 at the time of ON are transmitted to the control device 100. When the ON signal is input from the memory switch 70, the control device 100 sets the high-speed restriction mode S.

[0047] When high-speed restriction mode S is set, the memory 101 of the control device 100 receives and stores the detected values ​​of the main shift lever position sensor 99 and the HST pedal position sensor 96. During high-speed restriction mode S, high-speed side shifts based on the movement of the main shift lever 23 and the depression of the HST pedal 18 are disabled. In other words, a configuration is adopted in which shifts to a higher speed range than the stored operation range using the shift operating device 23, 18 are disabled. Specifically, the rotation angle of the trunnion shaft 47 is adjusted based on the detected value of the main shift lever position sensor 99 or the HST pedal position sensor 96 when the memory switch 70 is turned ON, thereby setting the speed. Therefore, even if the main shift lever 23 is moved to the high-speed side or the HST pedal 18 is depressed to the high-speed side, the tractor 1 can only travel up to the set speed. Here, regarding the method of setting the regulated vehicle speed when the memory switch 70 is turned ON, that is, whether to use the detection value of the main shift lever position sensor 99 or the HST pedal position sensor 96, there are several methods, such as giving priority to the main shift lever position sensor 99, giving priority to the HST pedal position sensor 96, setting it to the lower or higher vehicle speed corresponding to each detection value, or setting it to the detection value that changed immediately before the memory switch 70 was turned ON.

[0048] When high-speed regulation mode S is set, if operation of either the main shift lever 23 or the HST pedal 18 to the low-speed side is detected, the gear position is controlled to correspond to the operation position.

[0049] Therefore, in the low speed range, the shift is controlled to the operated position, and in the high speed range, the shift is restricted to the memorized shift position, so that it is easy to grasp the relationship between the operated position and the reproduction of the memorized shift position, and safe driving is possible.

[0050] When the memory switch 70 is turned ON again while the high-speed restriction mode S is set, the control device 100 attempts to update the memory by inputting the detected values ​​of the main shift lever position sensor 99 and the HST pedal position sensor 96 at that time. However, if either the main shift lever 23 or the HST pedal 18 is in a higher-speed position than the initially set detected position, the input is restricted and the updated memory is not accepted. Therefore, unexpected speed increases due to memory update can be avoided, ensuring safe driving.

[0051] High-speed restriction mode S is released by a release switch 71 disposed near the memory switch 70. When this release switch 71 is turned on, the vehicle speed can be changed by normal operation of the main shift lever 23 or HST pedal 18. When high-speed restriction mode S is released, if the position of the main shift lever 23 or HST pedal 18 is in a higher speed range than the speed set in high-speed restriction mode S, the high-speed restriction is continued until the shift position set by the main shift lever 23 or HST pedal 18 returns to the shift position when high-speed restriction mode S was set.

[0052] With this configuration, even if the main shift lever 23 or the HST pedal 18 is in the high-speed position when the high-speed restriction mode S is released, an unexpected increase in speed can be avoided, allowing safe driving.

[0053] 6 shows the gear shifting status of the main shift lever 23, which is configured to be able to shift from the maximum position (highest speed position) Max to the lowest speed creep position Min and to D mode, which switches to accelerator shifting mode. When high-speed restriction mode S is set, if memory position X is set by memory switch 70, in range Y between X and Max in FIG. 6, even if the main shift lever 23 is operated, the trunnion shaft 47 does not move from memory position X, and therefore the theoretical vehicle speed does not change. Meanwhile, in range Z between X and Min in FIG. 6, the trunnion shaft 47 moves in conjunction with the operation of the main shift lever 23, and the theoretical vehicle speed changes.

[0054] Next, the main shift lever 23 and memory switch 70 will be described based on an example of the configuration of the operating parts near the cockpit 7 inside the cabin. As shown in Figures 7 and 8, an armrest 80 is provided on one side of the cockpit 7 (the right side in the illustrated example) so that it can rotate up and down. The armrest 80 is connected to a bracket member 81A provided near the side of the cockpit 7 so that it can rotate freely about a horizontal axis, and is divided into an armrest section 82 in the rear half and an operating system arrangement section 83 in the front half. A cushioning material is attached to the upper surface of the armrest section 82.

[0055] The operation system arrangement section 83 in the front half forms a partition section 83C that separates the operation section into an outer operation section 83A and an inner operation section 83B. The outer operation section 83A is provided with a position lever 24 for raising and lowering the work equipment so that it can be moved forward and backward, and the inner operation section 83B is provided with a main speed change lever 23 as a speed change operation device so that it can be moved forward and backward. When the position lever 24 is tilted forward, the work equipment descends, and when tilted rearward, the work equipment rises. The main speed change lever 24 is configured to switch to a lower speed sequentially as it is tilted from the forward tilt side to the rearward tilt side, and the accelerator shift position is set at the rearward tilt end. When set to the accelerator shift position, the gear is switched to a predetermined speed by calculation based on the detected accelerator pedal depression amount and engine speed.

[0056] A vehicle speed restriction switch 86 is disposed behind the main speed change lever 23. When this switch 86 is turned on, the gear stage is calculated so that the detected vehicle speed does not exceed, for example, 15 km / h, and the vehicle is automatically shifted to a predetermined lower speed.

[0057] The operator uses his or her right hand to feel for the partition 83C, and when raising or lowering the work machine R, the operator feels for the position lever 24 on the outside of the partition 83C, and when changing gears, the operator feels for the main speed change lever 23 on the inside of the partition 83C, and the existence of the partition 83C makes it easy to touch and operate the desired operating lever without having to look at it. The curved top shape of the partition 83C is shaped so that it is higher than the operating parts of the position lever 24 and main speed change lever 23.

[0058] Next, we will explain the configuration of the operation panel 87 configured on the upper part of the right fender near the armrest 80. The operation panel 87 portion on the upper surface of the fender is divided into multiple areas. Specifically, it includes a first area 87A close to the outer operation unit 83A of the armrest 80, a second area 87B arranged at an angle from the slightly higher upper edge behind it, a third area 87C whose front portion is formed in a sloping convex shape 87Cp between the upper edge of the second area 87B and the inner wall of the intermediate support pillar 20, and a fourth area 87D which is slightly lower and forward of the sloping convex shape 87Cp of the third area 87C.

[0059] The first area 87A is equipped with a PTO switch 88, tillage depth adjustment dial 89, engine RPM memory 90, memory adjustment switch 91, automatic clutch switch 92A, and other components. The PTO switch 88 manually controls the rotation and stopping of the PTO shaft, while the tillage depth adjustment dial 89 sets the tillage depth during automatic tillage depth control mode. The engine RPM memory 90 employs a seesaw switch configuration to change between two preset engine RPMs with a single touch and is used when pausing and resuming work, such as during turning. The memory adjustment switch 91 also employs a seesaw switch configuration to arbitrarily increase or decrease the engine RPM set in the engine RPM memory 90. The automatic clutch switch 92A activates the automatic clutch brake stop function, which allows the vehicle to decelerate and stop simply by depressing the brake pedal. After the vehicle has stopped, the vehicle can be started again simply by releasing the brake pedal.

[0060] The first area 87A is provided at a height position substantially equal to that of the elbow rest portion 82 of the armrest 80.

[0061] The inclined second area 87B is equipped with an electronic hydraulic operation box 79, which can be opened and closed with a cover 79C. The electronic hydraulic operation box 79 is equipped with a travel selector switch for 2WD, 4WD, etc., work setting switches for reverse linked lift, swing linked lift, swing linked brake, etc., and other setting switches for auto switching of position and draft selection, and horizontal switching of the work implement between absolute horizontal, machine body parallel, and machine body inclination. This second area 87B is set at a slightly higher position than the first area 87A.

[0062] The third area 87C is provided with two external hydraulic control levers 75, 75, and the inclined surface of the convex slope 87Cp in front of them is provided with various switches associated with the automatic straight-ahead control function of the automatic steering mode, which will be described later. For example, a home screen call switch 76 for the sub-monitor (not shown), a screen changeover switch 77, and a position correction switch 78 are provided.

[0063] The fourth area 87D is equipped with a PTO selector switch 72, a mode selector dial 73, a memory switch 70, and a work setting call switch 74A. Of these, the PTO selector switch 72 can be set to either an automatic PTO rotation mode, which automatically stops the PTO shaft rotation when the implement begins to ascend and restarts it when it has descended a specified distance, or a manual mode, which does not perform these operations. The mode selector dial 73 corresponds to the various switches on the electro-hydraulic operation box 79, and when switching between tilling work and road driving, the drive state and various control settings can be set to the appropriate state with a single touch.

[0064] The memory switch 70 sets the high-speed restriction mode S. Functions are added to both a long press and a short press of the switch 70, and when the switch 70 is long pressed, the operating position of the main shift lever 23, i.e., the detection value of the main shift lever position sensor 99, is stored. A short press enters the high-speed restriction mode S, and a subsequent short press can cancel the mode S. With this configuration, the independent release switch 71 can be omitted.

[0065] Next, a configuration for obtaining an appropriate working speed through a combination of the position sensor 99 of the main shift lever 23, the engine RPM memory 90, the position sensor 94 of the sub-shift lever 21, etc. will be described. In FIG. 9, the control device 100 receives signals from the main shift lever position sensor 99 of the main shift lever 23, the sub-shift lever position sensor 94 of the sub-shift lever 21, the engine RPM memory 90, and the memory switch 70, and switches on the LCD display 110 between a screen that displays the set speed, the sub-gear position, and engine RPM memory 70 selection information, and a screen that displays the set speed for each sub-gear position. Reference numeral 111 denotes a display selector switch that switches between the screen displays set for each sub-gear position. The engine RPM memory 90 is provided with switches (two types, A and B in the illustrated example) that can set multiple engine RPMs to correspond to different tasks, and the LCD display 110 displays the set speed calculated from the engine RPM setting and the value detected by the main shift position sensor 99 of the main shift lever 23. In addition, since the set speed differs depending on the shift position of the sub-shift lever, it is calculated in accordance with the detection value of the sub-shift lever sensor 94, and the liquid crystal display unit 110 is configured to be able to display the sub-shift position and the set speed in correspondence with each other.

[0066] In the above embodiment, a hydrostatic continuously variable transmission (HST) has been described as the transmission, but other continuously variable transmissions such as a hydromechanical continuously variable transmission (HMT) may also be used. [Explanation of symbols]

[0067] 18 HST pedal (gear shifting device) 23 Main shift lever (shifting device) 41 Continuously variable transmission 70 Memory switch 71 Release switch 100 control device S High-speed regulation mode

Claims

1. In a work vehicle equipped with a continuously variable transmission (41) that changes speed continuously based on the operation of a speed change operating device (18, 23), a memory switch (70) is provided that detects the operating position of the speed change operating device (18, 23) and stores the detected operating position in a control device (100), the control device (100) has a high-speed restriction mode (S) that disables speed changes to the high-speed side corresponding to a speed change region faster than the stored operating position, and is configured to control the continuously variable transmission (41) to a speed change position corresponding to the operating position in a speed change region slower than the stored operating position in the high-speed restriction mode (S), The high-speed restriction mode (S) is released by operating a release switch (71), and if the shift position of the gear change operating device (18, 23) is in a higher speed range than the speed set and stored in the high-speed restriction mode (S) when the high-speed restriction mode (S) is released, the work vehicle continues to be restricted by the high-speed restriction until the shift position of the gear change operating device (18, 23) returns to the shift position when the high-speed restriction mode (S) was set.

2. 2. The work vehicle according to claim 1, wherein when the high speed restriction mode (S) is set and the memory switch (70) is operated again, the control device (100) inputs the detected values ​​of the gear change operating devices (18, 23) at this time to update the memory, and when the gear change operating devices (18, 23) are at a higher speed position than the set detected position, the control device (100) restricts the input and does not accept the update of the memory.

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