JP5708005B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as a tractor.

2. Description of the Related Art Work vehicles such as tractors and riding lawn mowers are known to be equipped with an auto cruise device that can automatically run at a certain speed when set at a certain speed.
For example, Patent Literature 1 below has a hydraulic continuously variable transmission, and when a forward pedal or a reverse pedal is depressed, a forward / reverse motor is driven according to the depression amount, and the hydraulic continuously variable motor is driven by the forward / reverse motor. In a moving vehicle in which a trunnion shaft of a transmission rotates in a normal rotation direction or a reverse rotation direction, a moving vehicle provided with a fixing means for fixing the rotation position of the trunnion shaft is disclosed.

  By fixing the rotation position of the trunnion shaft, the traveling speed can be maintained constant, and fuel consumption can be improved and work can be performed for a long time. When the auto-cruise function of the auto-cruise device is desired to be released, the work vehicle is stopped by being released electrically or mechanically by depressing the brake pedal or the clutch pedal.

JP 2006-125535 A

  In the work vehicle described in Patent Document 1, the auto-cruise function of the auto-cruise device is canceled by depressing the brake pedal, the clutch pedal, etc., but this operation is manual and performed by the operator (operator). Is. Therefore, for example, when an unexpected load is applied during work, the engine may stop if the worker continues the work without noticing that the load is applied to the engine. When the load is large, the auto-cruise device is not used from the beginning, but an inexperienced worker may turn on the auto-cruise device.

Examples of cases where the load increases are as follows.
In the case of lawn mowing work, there is a situation where weeds other than the lawn to be mowed increase, the lawn is wet, etc. In the case of snow removal work, the state of moist snow, foreign matter (such as mud) in the snow There are some situations.

  In order to avoid engine stop, it is desirable to cancel the auto-cruise function when working with a heavy load, but it is a burden on the worker to leave the determination to the worker.

  An object of the present invention is to provide a work vehicle equipped with an auto-cruise device that can release an auto-cruise function when a heavy load is being performed without placing a burden on an operator.

The above-described problems of the present invention are solved by the following solution means.
According to the first aspect of the present invention, the engine (3), the engine speed setting means (101) for setting the speed of the engine (3) to a constant speed, and the speed of the engine (3) are detected. And a trunnion shaft (30) for changing the inclination angle of the swash plate for adjusting the hydraulic pressure to be input and output to the engine (3). hydrostatic transmission device for outputting an output rotation speed based on the hydraulic pressure corresponding to the rotation angle of (30) and (7), a trunnion axis drive motor (66) for rotating the trunnion shaft (30), A transmission comprising a main transmission and a sub-transmission for shifting the output rotational speed from the hydrostatic transmission (7), and a motive power from the engine (3) is supplied to the hydrostatic transmission (7) and the transmission. Travel transmitted through (2), main shift operation means (62a, 62b) for operating the main shift by the main transmission device to the low speed side and the high speed side, and main shift by operation of the main shift operation means (62a, 62b). Main shift operation detecting means (63a, 63b) for detecting the shift, sub-shift operation means (12) for operating the sub-shift by the sub-transmission device to the low speed side and the high speed side, and the operation of the sub shift operation means (12) Sub-shift operation detecting means (65H, 65L) for detecting the sub-shift by means of, and the rotation angle of the trunnion shaft (30) of the hydrostatic transmission (7) corresponding to the depression amount, the trunnion shaft drive motor (66) An HST pedal (9) that is adjusted via the HST pedal, an HST pedal detection means (83) that detects the amount of depression of the HST pedal (9), and a traveling speed of the traveling device (2, 6) to keep constant For auto cruise driving A work unit (82), and auto-cruise traveling prohibiting operation means for inhibiting the auto-cruise traveling (93) by said auto cruise travel operation means (82), when the auto-cruise travel operation means (82) is operated The trunnion shaft drive motor (66) is controlled so as to maintain the rotation angle of the trunnion shaft (30) corresponding to the depression amount of the HST pedal (9) detected by the HST pedal detection means (83) at that time. The first auto-cruise function that keeps the traveling speed of the traveling devices (2, 6) constant, and during the traveling by the first auto-cruise function, and by the main transmission operation detecting means (63a, 63b) When the detected main shift is on the low speed side and the sub shift detected by the sub shift operation detecting means (65H, 65L) is on the high speed side, A function of canceling the first auto-cruise function when the engine speed detected by the engine speed detecting means (103) is lowered by a predetermined value or more from the constant speed set by the engine speed setting means (101). When the sub-shift detected by the sub-shift operation detecting means (65H, 65L) is on the high speed side, the auto-cruise traveling prohibiting operation means (93) is turned on to disable the first auto-cruise function. However, when the sub-shift detected by the sub-shift operation detecting means (65H, 65L) is not on the high speed side, the first auto-cruise function is effective even when the auto-cruise traveling prohibition operating means (93) is on. And when the auto-cruise traveling prohibition operating means (93) is operated to turn it off, the auxiliary transmission operation detecting means (65H, 65L) Subtransmission detected by it is a working vehicle equipped with a control device and (100) having an auto-cruise traveling prohibited acceptable function even high-speed side to enable the first automatic cruise function.

According to a second aspect of the present invention, there is provided an auto-cruise travel speed reproduction operating means (90) for reproducing the speed at the time of the previous auto-cruise travel, and the control device (100) is driven by the first auto-cruise function. The main shift detected by the main shift operation detecting means (63a, 63b) is on the low speed side, and the sub shift detected by the sub shift operation detecting means (65H, 65L) is on the high speed side. In this case, when the engine speed detected by the engine speed detecting means (103) decreases by a predetermined value or more from a fixed speed set by the engine speed setting means (101), the first auto cruise function And the neutral position of the trunnion shaft (30) of the hydrostatic transmission (7) from the position during travel by the first auto-cruise function. The second auto that keeps the traveling speed of the traveling device (2, 6) constant by controlling the trunnion shaft drive motor (66) so as to return to the half position and maintain the neutral half position. have a cruise function, further, previous trunnion shaft (30) of said at running by the first auto cruise function the auto-cruise traveling speed reproduction operation means (90) is operated hydrostatic transmission (7) Even if the auto-cruise traveling speed reproduction operating means (90) is operated when the vehicle is not traveling by the first auto-cruising function, the hydrostatic transmission (7) the trunnion shaft (30) is a working vehicle according to claim 1, wherein the chromatic autocruise traveling speed reproduction function that does not change the position of the previous auto-cruise traveling.

According to a third aspect of the present invention, the control device (100) is configured such that the engine speed detected by the engine speed detection means (103) during the traveling by the second auto-cruise function is the engine speed setting means ( 101), the trunnion shaft drive motor returns the trunnion shaft (30) of the hydrostatic transmission (7) to the position during travel by the first auto-cruise function when the rotational speed is increased to the fixed rotational speed set by (101). The work vehicle according to claim 2, having a function of controlling (66).
In the present specification, the left and right directions in the forward direction of the work vehicle are referred to as left and right, respectively.

According to the first aspect of the present invention, the auto-cruise traveling is canceled when a decrease in the engine speed is detected during auto-cruise traveling, when the sub-shift is on the high speed side and the main gear shift is on the low speed side. By doing so, troubles such as engine stop can be avoided because high-load work at a constant vehicle speed at high speed is not performed.
Further, even when auto-cruise travel is prohibited by the auto-cruise travel prohibition operation means (93), auto-cruise travel is possible if the sub-shift is not on the high speed side. Further, when the auto-cruise travel prohibition operating means (93) is operated to turn off, the auto-cruise travel is possible even when the sub-shift is on the high speed side. Driving is possible.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, by detecting the high load during auto-cruise traveling, the position of the trunnion shaft (30) is returned to the neutral side, It is possible to reliably reduce the speed of the work vehicle. Therefore, troubles such as engine stop can be avoided. And, by automatically driving at a constant speed at a low speed, the burden on the operator's operation is small.
In addition, the auto-cruise traveling at the previous speed becomes possible by setting the speed at the previous auto-cruise traveling by the operation of the auto-cruise traveling speed reproduction operation means (90) during the auto-cruise traveling.

  According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, after the trunnion shaft (30) is returned to the neutral side, the engine speed is increased and the engine speed setting means is provided. After returning to the constant rotational speed set by (101), the vehicle speed of the work vehicle before the engine rotational speed decreases is controlled by controlling the trunnion shaft (30) to return to the previous position. The work vehicle can run smoothly and workability can be improved.

It is a left view of the work vehicle of the Example of this invention. FIG. 2 is a power transmission system diagram in a transmission of the work vehicle of FIG. 1. FIG. 3 is a partially enlarged view of the power transmission system diagram of FIG. 2. It is a perspective view of the operation part of the subtransmission lever of the working vehicle of FIG. It is a block diagram of the control apparatus of the working vehicle of FIG. It is a flowchart of control by the control apparatus of the working vehicle of FIG. It is a flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is a flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the relationship between the engine speed of the working vehicle of this embodiment, and the control angle of a trunnion shaft. It is the figure which showed the relationship (another example) between the engine speed of a working vehicle, and the control angle of a trunnion shaft. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed another example of the block diagram of the control apparatus of FIG. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the flowchart of another example of control by the control apparatus of the working vehicle of FIG. It is the figure which showed the relationship between the engine speed of the conventional work vehicle, and the control angle of a trunnion shaft.

Embodiments of the present invention will be described below with reference to the drawings.
As an example of the vehicle, a left side view of a multipurpose work vehicle (hereinafter referred to as a work vehicle) is shown in FIG. 1A, and FIG. 2 shows a power transmission system diagram in the transmission of the work vehicle of this embodiment, FIG. 3 shows a partially enlarged view of the power transmission system diagram of FIG. 2, and FIG. FIG. 5 shows a block diagram of the control device.

  A vehicle body of a work vehicle having a riding mode of riding four-wheel drive is operated while steering the front wheel 2 with the steering handle 1 or is operated by steering the front wheel 2 and the rear wheel 6 (traveling device). The engine 3 is mounted on the rear part of the fuselage, a transmission case 14 and the like are integrally connected to the front side of the engine 3, and a rear axle housing (not shown) is provided at the rearmost part of the transmission case 14. The rear wheel 6 is mounted on the shaft. Further, the rotational speed of the output shaft 27 of the hydrostatic continuously variable transmission (HST) 7 shown in FIG. 2 is changed according to the depression amount of the HST pedal 9.

  Further, a working machine such as a lawn mower, a snow remover, or a cleaner (with a rotating brush attached) (not shown) is pulled to the front of the vehicle body via the lifting link device 10. Further, a cockpit 5 is provided in front of the vehicle body, and in the vicinity of the driver's seat 11 in the cockpit 5, there are various levers such as an auxiliary transmission lever 12 (FIG. 4) and a position lever for changing the height of the work implement. An operation mode setting button (not shown), an operation mode setting button (not shown, for selecting a slow response speed of the trunnion shaft 30 (FIGS. 2 and 3) of the hydrostatic continuously variable transmission) and cruise Various switches such as a control ON / OFF switch 82 (FIG. 5), an HST pedal 9 and an HST pedal position sensor 83 for detecting the position (depression amount) of the HST pedal 9 are provided. The vehicle speed sensor 74 (FIG. 5) is attached to the mission case 14, and is configured to pick up the number of rotations of the shaft that can detect the vehicle speed.

  Further, when traveling on the road (non-working traveling), the advancing direction of the aircraft is determined by a forward / reverse lever 88 provided on the side surface of the steering handle 1 as shown in the perspective view of the main part of the cab portion of FIG. By depressing the HST pedal 9 provided below the steering handle 1, the engine speed increases and the trunnion shaft 30 of the hydrostatic continuously variable transmission (HST) 7 rotates. Specifically, the engine speed increases to approximately the rated speed during the first 1/4 stroke of the depression of the HST pedal 9, and the trunnion shaft 30 rotates with the remaining 3/4 stroke. That is, the speed is changed from zero speed to the highest speed within the range of the depression of the HST pedal 9 of the 3/4 stroke.

  Further, pedals such as a brake pedal 8 for releasing control to keep the vehicle speed, which will be described later, are provided. A clutch pedal 89 provided below the steering handle 1 is used to turn on and off a clutch (not shown) in the mission case 14.

The sub-transmission lever 12 (see FIG. 4) is rotated along the lever guide 64 so that the sub-transmission device described later can be set to “high speed”, “neutral”, or “low speed” via the link mechanism. It is configured to switch manually.
Further, the rotational speed of the output shaft 27 of the hydrostatic continuously variable transmission (HST) 7 shown in FIG. 2 is changed according to the depression amount of the HST pedal 9.

  During work travel, the engine speed is increased to a substantially rated speed by the accelerator lever 101, and when the HST pedal 9 is depressed at a constant engine speed (maximum from around the rating), the trunnion shaft 30 rotates and accelerates. . At this time, the engine speed is maintained even if the operator releases his hand from the accelerator lever 101. That is, the accelerator lever 101 is an operating means for setting the engine speed during work travel. The engine speed (rpm) is detected by the engine speed sensor 103. The engine speed sensor 103 detects the rotation of the crankshaft of the engine 3, and the position of the engine speed sensor 103 varies depending on the type of the engine 3.

  The transmission case 14 has a configuration in which four hollow cases of a front case 15, a connection case 16, an intermediate case 17 (FIG. 2), and a rear case 18 (FIG. 3) are connected, and an input shaft 19 that is pivotally supported by the rear case 18. The power of the engine 3 is input to (FIG. 3), and the rotation of the input shaft 19 is transmitted to the first relay shaft 23 by the speed increasing gears 21 and 22 in the input case 20, and further the gear on the first relay shaft 23. The speed is increased by a speed increasing gear 25, and a hydraulic input shaft 7c of a variable capacity hydraulic pump 7a of a hydrostatic continuously variable transmission (HST) 7 is spline engaged with the speed increasing gear 25.

The input case 20 is provided in order to increase the output rotation of the engine 3 to enable high-speed traveling, and is attached to the inside of the input case 20 using a conventional transmission vehicle mission case. Thus, since it is set as the structure which accelerates with the input case 20, it becomes unnecessary to raise an engine speed at the time of high-speed driving | running | working, and this can aim at reduction of a noise and improvement of a fuel consumption rather than the conventional transmission.
Further, the rotational speed of the output shaft 27 of the constant displacement hydraulic motor 7b is changed by the swash plate of the variable displacement hydraulic pump 7a through the trunnion shaft 30 interlocked with the HST pedal 9.
On the other hand, since the PTO drive shaft 26 is directly connected to the hydraulic input shaft 7c inside the variable displacement hydraulic pump 7a of the hydrostatic continuously variable transmission 7, the hydraulic pressure of the HST variable displacement hydraulic pump 7a is constant. It rotates at the same rotational speed as the input shaft 7c.

  The PTO drive shaft 26 is directly connected to a drive shaft 28 having a gear 29, and the power of the gear 31 meshing with the gear 29 is transmitted to the counter gear 33 on the counter shaft 32 after the PTO, and then via the PTO clutch 34. The PTO counter counter shaft 35 passes through the front case 15 and is transmitted to a PTO counter shaft and a PTO counter gear (not shown) integrated with the PTO pre counter shaft 35. Power is output to a PTO on / off gear on a PTO output shaft (not shown).

  In addition, the driving force of the travel output shaft 27 of the hydrostatic continuously variable transmission 7 is transmitted through the gear 40a to the gear 40b and the gear 40c of the transmission shaft 40 constituting the gear-meshing main transmission sequentially through the main transmission. This structure is capable of transmitting to the large gear 42 and the intermediate gear 43 on the shaft 41. Further, a sub-transmission high-speed small gear 44a and a sub-transmission low-speed large gear 44b are provided at positions adjacent to the middle gear 43 on the main transmission shaft 41. Further, the sub-transmission low-speed large gear 44b is adjacent to the main transmission shaft 41. A front wheel drive gear 37 is provided at the position.

  On the clutch shaft 45 provided in parallel with the main transmission shaft 41, there are provided transmission clutch gears 46 and 47 that are always meshed with the large gear 42 and the intermediate gear 43, respectively. A hydraulic clutch (high speed side hydraulic clutch) 51 and a hydraulic clutch (low speed side hydraulic clutch) 52 are provided on the clutch shaft 45 therebetween, and a differential device 53 is connected to the output side of the clutch shaft 45. Power is transmitted from the differential device 53 to a front wheel output shaft (not shown), and the front wheel 2 is driven.

  In order to connect the high speed side hydraulic clutch 51 and the low speed side hydraulic clutch 52 by the high speed hydraulic clutch solenoid 49 and the low speed hydraulic clutch solenoid 50 shown in FIG. 5, respectively, the main shift lever 12 shown in FIG. This is done by pressing the shift switches 62a and 62b.

  When the main transmission switch 62a ("+" sign side) and the main transmission switch 62b ("-" sign side) are pressed, the high speed hydraulic clutch solenoid 49 and the low speed hydraulic clutch solenoid 50 shown in FIG. Thus, the high speed side hydraulic clutch 51 and the low speed side hydraulic clutch 52 are respectively connected.

  As shown in FIG. 4, when the auxiliary transmission lever 12 is operated to the high speed side or the low speed side in the lever guide 64, the auxiliary transmission lever sensor 65H on the high speed side and the auxiliary transmission lever sensor 65L on the low speed side respectively. The shift position of the transmission lever 12 can be detected.

  When the engine 3 is started, either one or both of the forward / reverse lever 88 and the auxiliary transmission lever 12 are set to the neutral position. Start (starter does not rotate) except in the neutral position. The forward / backward switching of the forward / reverse lever 88 is detected by a switch (forward / reverse lever sensor) 73 at the base of the forward / reverse lever 88.

During forward travel (first speed and second speed), the forward / reverse lever 88 is first set to the forward side. Next, the first speed (low working speed) and the second speed (high working speed) can be selected. The first gear is used for snow removal work with a snow remover. However, it can also be used for other operations. Also, snow removal work may be performed at the second speed. The second speed is particularly suitable for lawn mowing work with a lawn mower, but it can also be used for other work, and the lawn mowing work may be performed at the first speed. Moreover, the operation | work with mounting | wearing a street cleaner (rotary brush) may also be performed by 1st speed or 2nd speed.
When the auxiliary transmission lever 12 is set to the low speed side, the auxiliary transmission low speed small gear 48b meshes with the auxiliary transmission low speed large gear 44b and preparation for power transmission is made.

  In the case of the first speed, the main transmission switch 62b is turned on, the low speed side hydraulic clutch 52 of the main transmission is connected, and preparation for power transmission from the gear 43 to the gear 47 is completed. In the case of the second speed, the main transmission switch 62a is turned on to connect the high-speed hydraulic clutch 51 of the main transmission, and preparation for transmission of the driving force from the gear 42 to the gear 46 can be made. Since the main transmission switches 62b and 62a function even when the auxiliary transmission lever 12 is neutral, the main transmission switch 62b or 62a is turned on first, and then the auxiliary transmission lever 12 is operated at a low speed or a high speed later. Sometimes.

Further, the work vehicle starts running by raising the engine speed to a certain value by the accelerator lever 101 and depressing the HST pedal 9. Corresponding to the depression amount of the HST pedal 9 (detected by the HST pedal position sensor 83), the trunnion shaft 30 of the variable hydraulic pump 7a of the hydraulic continuously variable transmission (HST) 7 is driven by a trunnion shaft drive motor (forward rotation, forward side, It is rotated at 66 (reverse side by reverse rotation).
As the trunnion shaft 30 rotates, the rotational power of the engine 3 is output from the output shaft 27 of the constant capacity hydraulic motor 7b of the hydraulic continuously variable transmission (HST) 7, and the obtained power is output to the output shaft 27, transmission The shaft 40, the gear 40a, the gear 40b, the gear 40c and the main transmission shaft 41 are transmitted.

  As for the power of the main transmission shaft 41, the first speed is output when the low speed side hydraulic clutch 52 is connected, and the power is sequentially transmitted to the gear 43, the gear 47, the low speed side hydraulic clutch 52, and the shaft 45. In the case of the second speed to which the high speed side hydraulic clutch 51 is connected, power is transmitted to the gear 42, the gear 46, the high speed side hydraulic clutch 51, and the shaft 45 in order. The power of the shaft 45 is sequentially transmitted to the gear 48b, the large sub-speed gear 44b, the front wheel drive gear 37, and the rear wheel drive gear 56. Then, the left and right front wheels 2 pass through the differential device 53.

  Further, the PTO drive shaft 26 of the variable hydraulic pump 7a of the hydrostatic continuously variable transmission 7 is always rotated by the rotation of the engine 3 regardless of whether the HST pedal 9 is depressed (corresponding to the engine speed). ). The power of the PTO drive shaft 26 is transmitted to the gear 29, the gear 31, the gear 33, and the post-PTO counter shaft 32. The counter shaft 32 after PTO is always rotating.

  When the PTO hydraulic clutch 34 is connected, the power of the post-PTO countershaft 32 is transmitted to the pre-PTO countershaft 35 to drive the work implement. On the other hand, when four-wheel drive is selected, a four-wheel drive lever (not shown) is operated to mesh the rear wheel output gear 60 with the gear 58. Then, the power of the rear wheel drive gear 56 is transmitted to the counter gear 57, the gear 58, the rear wheel output gear 60, and the rear wheel drive shaft 61, and further passes through the differential device 53 to drive the rear wheel 6.

Since the shift by the sub-shift lever 12 is a gear slide type, a shift cannot be performed while traveling. However, even with a gear slide type, if the synchro mechanism is configured, it is possible to shift while traveling.
Since the output of the main transmission is performed by the connection of the hydraulic clutches 51 and 52, shifting while traveling is possible. Therefore, when the main shift switches 62b and 62a are alternately turned on and off during work travel, the first speed (working low speed) and the second speed (working high speed) can be switched.

  Further, during reverse travel, reverse travel is started by operating the forward / reverse lever 88 to the reverse side and depressing the HST pedal 9. The reverse speed at this time is adjusted by the amount of depression of the HST pedal 9. That is, the trunnion shaft 30 of the variable hydraulic pump 7a of the hydraulic continuously variable transmission (HST) 7 is moved forward by the trunnion shaft drive motor 66 in accordance with the depression amount of the HST pedal 9 (detected by the HST pedal position sensor 83). The engine 3 rotates in the reverse direction, and the rotational power of the engine 3 is output from the output shaft 27 of the quantitative hydraulic motor 7b of the hydraulic continuously variable transmission (HST) 7 in a reverse rotation from that at the time of forward movement.

  When only the brake pedal 8 is depressed, the disc brakes (not shown) of the front wheels 2 and the rear wheels 6 are operated, and the trunnion shaft 30 is set to the neutral position. When both the brake pedal 8 and the HST pedal 9 are depressed, the function of the brake pedal 8 is activated, and the control device (controller) 100 ignores the signal from the HST pedal 9. The amount of depression of the brake pedal 8 is detected by a brake pedal sensor 92 such as a position sensor provided at the rotation fulcrum of the brake pedal 8.

When traveling on the road, the forward traveling (3rd speed and 4th speed) is basically selected, and the following travel control is performed.
That is, both the 3rd speed and the 4th speed are the low speed and the high speed when traveling on the road, and basically the work using the work machine is not performed, but depending on the conditions, the work using the work machine is also performed at the 3rd speed or the 4th speed. There is. When the auxiliary transmission lever 12 is set to the high speed side, the auxiliary transmission high speed large gear 48a of the auxiliary transmission is engaged with the auxiliary transmission high speed small gear 44a, and preparation for power transmission is made.

In the case of the third speed, when the main transmission switch 62b is turned on, the low speed side hydraulic clutch 52 of the main transmission is connected, and preparation for power transmission from the middle gear 43 to the gear 47 is made. In the case of the fourth speed, the main shift switch 62a is turned on. Then, the high speed side hydraulic clutch 51 of the main transmission is connected, and preparation for power transmission from the gear 42 to the gear 46 is made.
As described above, the work vehicle according to the present embodiment is capable of working in any of the first to fourth speeds, and the operator determines which speed is selected according to the situation.

  Then, at the time of work traveling, first, the accelerator lever 101 is operated to set the engine speed to a constant speed (the engine speed is in accordance with the operation amount, but usually the working speed is between the rated speed and the maximum speed). When the HST pedal 9 is raised, the angle of the trunnion shaft 30 of the hydrostatic continuously variable transmission 7 changes and the work vehicle travels. The rated rotational speed varies depending on the type of engine 3. Then, the operator (operator) operates the accelerator lever 101 while looking at the engine tachometer (not shown).

  When the cruise control on / off switch 82 is turned on while the work vehicle is traveling, auto-cruise traveling is automatically performed at a constant speed while maintaining the speed of the work vehicle. That is, when the cruise control on / off switch 82 is turned on, the amount of depression by the HST pedal 9 at that time is detected by the HST pedal position sensor 83, and the traveling speeds of the front wheels 2 and the rear wheels 6 based on the detected values. In order to maintain a constant value, the trunnion shaft drive motor 66 is driven by the control device 100 to control the trunnion shaft 30 (auto cruise function).

  If the foot is released from the HST pedal 9 during auto-cruise traveling, the HST pedal 9 returns to the original position (position before stepping on), but the vehicle speed of the work vehicle is maintained. Further, when the brake pedal 8 is depressed, the auto cruise traveling (auto cruise function) is canceled. During auto-cruise traveling, the rotation angle of the trunnion shaft 30 is maintained, so that the vehicle speed of the work vehicle is kept constant (constant speed traveling).

  When the speed of the work vehicle decreases on a slope or the like, the vehicle speed when the cruise control on / off switch 82 is turned on is maintained by controlling the trunnion shaft 30 by the control device 100.

  The cruise control memory switch 90 (FIG. 5) is a switch for reproducing the latest auto cruise traveling speed. For example, when the cruise control memory switch 90 is pressed during auto-cruise traveling (for example, when the vehicle speed is 5 km / h), the previous auto-cruise traveling speed (for example, 10 km / h) is obtained, and this speed (10 km / h) Take an auto cruise. Further, when the cruise control memory switch 90 is pressed when the vehicle is not in an automatic cruise traveling, the operation is invalid and does not function.

  In the work vehicle of the present embodiment, the auxiliary transmission lever 12 is at the high speed side and the third speed in which the low speed side is selected by the main transmission switches 62a and 62b, that is, at the time of high speed work traveling at a predetermined speed or more, and A control device 100 having a function of canceling the auto-cruise traveling is provided when a decrease in the engine rotational speed is detected by the engine rotational speed sensor 103 during cruise traveling.

  In the work vehicle according to the present embodiment, auto-cruise traveling is possible even at a relatively high speed of 3rd speed. However, when the work is performed with a heavy load, the worker is informed that the engine 3 is loaded. If you continue to work without noticing, there is a possibility that the engine will stop.

  However, according to this configuration, when a decrease in the engine speed is detected during auto-cruise traveling, that is, when a high load is detected, the auto-cruise traveling is canceled to perform high-load work at a constant vehicle speed at high speed. Because it does not, troubles such as engine stop can be avoided.

FIG. 6 shows a flowchart of control by the work vehicle control device of FIG.
When the engine 3 is started and the running of the work vehicle is started, it is determined by the control device 100 whether the cruise control on / off switch 82 is detected by the on / off signal of the cruise control on / off switch 82. In the case of the entering auto-cruise traveling, the shift position of the auxiliary transmission lever 12 is detected by the auxiliary transmission lever sensor 65, specifically, the high-speed side auxiliary transmission lever sensor 65H and the low-speed side auxiliary transmission lever sensor 65L.

  When the shift position of the sub-shift lever 12 is detected to be the high-speed side by the high-speed sub-shift lever sensor 65H, and the low-speed hydraulic clutch 52 is selected by operating the main shift switches 62a and 62b (third speed) The engine speed is monitored by the engine speed sensor 103, and when a decrease in the engine speed is detected, the auto-cruise traveling is canceled.

  The main shift switches 62a and 62b only select either the high-speed hydraulic clutch 51 or the low-speed hydraulic clutch 52, and the following shift modes (1st to 4th) are set.

First, a description will be given of when the low speed side sub-shift lever sensor 65L is engaged.
The high speed side hydraulic clutch 51 or the low speed side hydraulic clutch 52 is selected by the main transmission switches 62a and 62b.
When the low-speed hydraulic clutch 52 is currently selected (first speed), nothing happens even if the main shift switch 62b ("-" sign side) is pressed, and the main shift switch 62a ("+" sign side) is turned on. When pressed, the high speed side hydraulic clutch 51 is engaged (second speed).

  When the high-speed hydraulic clutch 51 is currently selected (second speed), nothing happens even if the main shift switch 62b ("+" sign side) is pressed, and the main shift switch 62a ("-" sign side) ) Is pressed, the low speed hydraulic clutch 52 is engaged (first speed).

Next, a description will be given of when the auxiliary transmission lever sensor 65H on the high speed side is engaged.
The high speed side hydraulic clutch 51 and the low speed side hydraulic clutch 52 are selected by the main transmission switches 62a and 62b.
When the low-speed hydraulic clutch 52 is currently selected (third speed), nothing happens when the main shift switch 62b ("-" sign side) is pressed, and the main shift switch 62a ("+" sign side) is turned on. When pressed, the high speed side hydraulic clutch 51 is engaged (fourth speed).

When the high-speed hydraulic clutch 51 is currently selected (fourth speed), nothing happens even if the main shift switch 62b ("+" sign side) is pressed, and the main shift switch 62a ("-" sign side) ) Is pressed, the low speed hydraulic clutch 52 is engaged (third speed).
Which of the high speed side hydraulic clutch 51 and the low speed side hydraulic clutch 52 is connected by the operation of the main transmission switches 62a and 62b described above is determined by the main transmission high speed side clutch sensor 63a (high speed side). This is determined by an input signal to the control device 100 from the main transmission low speed side clutch sensor 63b (for detecting the low speed side hydraulic clutch 52).

  Then, in the case of the relatively high speed of 3rd speed, when the engine speed has decreased by a predetermined value or more from the working speed (rated speed to maximum speed, A (rpm)), the auto-cruise traveling is performed. To release. The rated rotational speed and the maximum rotational speed vary depending on the type of the engine 3 mounted. For example, when the rated rotational speed is 2600 rpm and the maximum rotational speed is 2800 rpm, the case where the rotational speed is lower than 2000 rpm is used as a criterion.

When working, the operator works the accelerator lever 101 while raising the engine to near the rated value while looking at an engine tachometer (such as a tachometer). In addition, during auto-cruise traveling, the engine speed is constant when a normal load is not applied.
When the auto-cruise traveling is canceled during the working traveling, the traveling state is set in accordance with the positions of the forward / reverse lever 88, the accelerator lever 101, and the HST pedal 9.

On the other hand, when the decrease in the engine speed is not detected, the auto-cruise traveling is continued. The fact that a decrease in the engine speed is detected during auto-cruise driving means that it is possible to determine that the work vehicle is being pulled and the work vehicle is under heavy load because the work equipment is being pulled. In this case, by canceling the auto-cruise traveling, troubles such as engine stop can be avoided because high-load work at a constant vehicle speed at high speed is not performed.

  Further, in the case of the above-described auto-cruise traveling, and the auxiliary transmission lever 12 is at the high speed side and the low speed side hydraulic clutch 52 is selected by the main transmission switches 62a and 62b, that is, the high speed traveling above the predetermined speed. When a decrease in the engine speed is detected by the engine speed sensor 103 during work, the control device 100 changes the position of the trunnion shaft 30 to the current position (the position of the trunnion shaft 30 corresponding to the speed during auto-cruise traveling, Control may be performed so as to return to the neutral side to a half position (rotation angle (B / 2) degree) of the moving angle (B degrees) and maintain that position (position returned to the neutral side). . When the trunnion shaft 30 rotates from the neutral position, the traveling speed of the work vehicle increases, and when the trunnion shaft 30 returns to the neutral side, the traveling speed decreases.

  If the function of keeping the traveling speed of the work vehicle constant by maintaining the rotation angle of the trunnion shaft 30 is an auto-cruise function, the first auto-cruise function when the rotation angle of the trunnion shaft 30 is B degrees. When the rotation angle of the trunnion shaft 30 is (B / 2) degrees (relatively high speed automatic constant speed), it can be said to be the second auto-cruise function (relatively low speed automatic constant speed).

  The position (rotation angle) of the trunnion shaft 30 is detected by a trunnion sensor 70. The trunnion sensor 70 is provided inside the hydrostatic continuously variable transmission 7, detects the trunnion shaft 30 protruding from the main body of the hydrostatic continuously variable transmission 7, There are various types provided in the link mechanism between the trunnion shaft drive motor 66 and the like.

  If auto-cruise driving is enabled at the relatively high speed of 3rd speed, the engine continues to operate without the operator being aware that the engine is under load, such as when working with heavy loads. May cause a stop.

  However, according to this configuration, when a decrease in the engine speed is detected during auto-cruise traveling, that is, when a high load is detected, the trunnion shaft 30 is controlled to return to the neutral side, and By maintaining the position, the speed of the work vehicle can be surely reduced. Therefore, troubles such as engine stop can be avoided because high-load work at a constant vehicle speed at high speed is not performed. And, by automatically driving at a constant speed at a low speed, the burden on the operator's operation is small.

FIG. 7 shows a flowchart of another example of control by the work vehicle control device of FIG.
When the engine 3 is started and the work vehicle starts to travel, it is determined by detecting the on / off signal of the cruise control on / off switch 82 whether or not the auto cruise is running, and the cruise control on / off switch 82 is turned on. In the case of traveling, the shift position of the auxiliary transmission lever 12 is detected by the high-speed auxiliary transmission lever sensor 65H and the low-speed auxiliary transmission lever sensor 65L. When the shift position of the sub-shift lever 12 is detected to be the high-speed side by the high-speed sub-shift lever sensor 65H, and the low-speed hydraulic clutch 52 is selected by operating the main shift switches 62a and 62b (third speed) The engine speed is monitored by the engine speed sensor 103, and when a decrease in the engine speed is detected, the auto-cruise traveling is canceled. Up to this point, the flow is the same as that in FIG.

  In this flow (FIG. 7), when a decrease in the engine speed is detected, the controller 100 returns the position of the trunnion shaft 30 to the neutral position to half the position during auto-cruising and maintains the position. Control (the second auto-cruise function, the speed during auto-cruise traveling falls to half the speed). On the other hand, when a decrease in engine speed is not detected, control is performed by the control device 100 so that the position of the trunnion shaft 30 remains unchanged (the first auto-cruise function is maintained, and the speed during auto-cruise traveling does not change). ).

  If a decrease in engine speed is detected during auto-cruise driving, that is, if a high load is detected, the position of the trunnion shaft 30 is returned to the neutral side, and control is performed to maintain that position. The speed of the work vehicle can be surely reduced, and troubles such as engine stop can be avoided.

  And after returning the position of the trunnion shaft 30 to the neutral side to the current half position as described above, the rotational speed of the engine 3 rises and returns to the rotational speed before returning the position of the trunnion shaft 30 to the neutral side. Then, the trunnion shaft 30 may be controlled to return to the previous position.

  When the rotational speed of the engine 3 increases and returns to the rotational speed before returning the position of the trunnion shaft 30 to the neutral side, it is no longer a high load state, so even if the position of the trunnion shaft 30 is returned to the previous position. There is no problem. Further, by returning the position of the trunnion shaft 30 to the previous position, the vehicle speed of the work vehicle can be quickly returned to the vehicle speed before the engine speed decreases, and the work vehicle travels smoothly and the workability is improved. Can be improved.

FIG. 8 shows a flowchart of another example of control by the work vehicle control device of FIG.
In this flow, when a decrease in the engine speed is detected during auto-cruise traveling, the trunnion shaft 30 is controlled to return to the neutral side and maintained at that position, while a decrease in the engine speed is not detected. Is the same as FIG. 7 until the control device 100 controls the trunnion shaft 30 so that the position of the trunnion shaft 30 remains unchanged.

  And after returning the position of the trunnion shaft 30 to the neutral side to the half position (rotation angle (B / 2) degree), the rotational speed of the engine 3 is increased to the original rotational speed (A (rpm)). When returning, control is performed so that the position of the trunnion shaft 30 is also returned to the previous position (rotation angle B degrees). On the other hand, if the rotational speed of the engine 3 does not increase or does not return to the previous rotational speed (A (rpm)) even if it increases, the position of the trunnion shaft 30 is not changed, that is, the position of the trunnion shaft 30. Return to the neutral side.

  When the rotational speed of the engine 3 increases and returns to the rotational speed set by the accelerator lever 101, the engine is no longer in a high load state. Therefore, by returning the position of the trunnion shaft 30 to the previous position, the vehicle speed of the work vehicle can be promptly returned to the vehicle speed before the engine rotational speed decreases, and the work vehicle can be smoothly traveled and the workability is improved. Can be improved.

  On the other hand, regardless of whether or not auto-cruising is performed, when the sub-shift lever 12 is at the high speed side (the main shift switch 62 is the main shift switch 62b (“−” sign side)) and the main shift switch 62a (“+”). The control device 100 may control the trunnion shaft 30 to return to a maximum half (50%) position when the engine speed decreases. That is, when the load is applied to the work vehicle and the engine speed is reduced during the work traveling, the position of the trunnion shaft 30 before the load is applied is assumed to be 100% (not necessarily the upper limit rotation angle). Keep the position in half (50%).

In FIG. 9, the relationship between the engine speed of the working vehicle of this embodiment and the control angle of the trunnion shaft 30 is shown. FIG. 19 shows the relationship between the engine speed of a conventional work vehicle and the restriction angle of the trunnion shaft.
As shown in FIG. 19, conventionally, when the sub-shift lever 12 is on the high speed side, the load is applied and the engine speed is the number of rotations during work (the number of rotations during normal work is near the rated value to the maximum value). The trunnion shaft 30 before the load is applied to the trunnion shaft 30 when the load is lowered from the vicinity) (for example, when the rated rotation speed is 2600 rpm, the maximum rotation speed is 2800 rpm, and the rotation speed is lower than 2000 rpm). The position is returned to the neutral side from the position (100%) to a maximum position of 70%.

However, when the trunnion shaft 30 is returned to the neutral side to this extent (about 70%), if the heavy duty operation is performed in the high speed state where the sub transmission lever 12 is on the high speed side, the high speed side of the sub transmission lever 12 will be shown. It is conceivable that a load is applied to these gears (sub-transmission high-speed small gear 44a, sub-transmission high-speed large gear 48a), causing a problem.
However, according to this configuration, as shown in FIG. 9, if a decrease in the engine speed is detected even when the work vehicle is working at a high speed in a high load state, the trunnion shaft 30 before the load is applied is detected. The load applied to the gear on the high speed side of the auxiliary transmission lever 12 is reduced by returning to the neutral side from the position (100%) to the neutral position, that is, returning more than the conventional position. be able to. Accordingly, it is possible to avoid problems associated with the high-speed gear of the auxiliary transmission lever 12.

FIG. 10 shows the relationship (another example) between the engine speed of the work vehicle and the restriction angle of the trunnion shaft 30.
Also, when the sub-shift lever 12 is on the high speed side and the engine speed falls from the working speed (the working speed is near the rated value to the maximum) and falls below a predetermined value. The control device 100 may control the time to start the operation of returning the trunnion shaft 30 to the neutral side.

  For example, during a work run at a rated speed of 3200 rpm, the engine speed starts to decrease when some load acts on the work vehicle. At the same time, the control device 100 controls the trunnion shaft 30 in the neutral position in order to avoid this load, thereby reducing the vehicle speed of the work vehicle.

  As a condition for this low speed, the trunnion shaft 30 was controlled in the neutral position direction when the engine speed decreased to 1900 rpm as shown in FIG. 19, but in this configuration, as shown in FIG. When the engine speed decreases to 2000 rpm, the trunnion shaft 30 is controlled in the neutral position direction.

  Note that the rated speed and the maximum speed are different depending on the engine 3 to be mounted, and the speed at which the work is actually performed is also set by the operator, and thus differs. As described above, for example, when the rated rotation speed is 2600 rpm and the maximum rotation speed is 2800 rpm, the case where the rotation speed is lower than 2000 rpm during the work, such as when the rotation speed is less than about 70%, may be used as the determination criterion. .

  In this way, before the engine speed decreases to 1900 rpm, the trunnion shaft 30 is controlled in the direction of the neutral position at the time of 2000 rpm where the rotational speed is higher than that, so that the trunnion shaft 30 can be controlled as compared with the conventional case. The timing to start the operation to return to the neutral side is advanced. By quickly returning the trunnion shaft 30 to the neutral side, the load on the work vehicle can be quickly reduced. Therefore, it is possible to reduce the load applied to the high-speed side gear of the auxiliary transmission lever 12, and to avoid problems associated with the high-speed side gear of the auxiliary transmission lever 12.

  In the work vehicle according to the present embodiment described above, the auto-cruise traveling is possible even when the auxiliary transmission lever 12 is at the high speed side and the low speed side hydraulic clutch 52 is selected by the operation of the main transmission switches 62a and 62b.

  On the other hand, when the sub-shift lever 12 is on the high speed side, even if the cruise control on / off switch 82 is pressed (operating on) regardless of the decrease in the engine speed, the automatic cruise traveling is not allowed. Therefore, troubles such as engine stop can be avoided.

  Auto-cruise that does not allow auto-cruise traveling when the sub-shift lever 12 is on the high speed side (when the shift position of the sub-shift lever 12 is detected on the high speed side by the high speed side sub shift lever sensor 65H). A travel prohibition switch 93 is provided, and the auto cruise travel prohibition switch 93 is always on.

  In the control device 100 shown in the flow of FIGS. 6 to 8, the auto-cruise travel prohibition switch 93 is turned off, so that the auto-cruise can be performed even when the auxiliary transmission lever 12 is on the high speed side (in the case of the third speed or the fourth speed). Driving is possible. For example, when the load is low, the auto cruise traveling can be performed by turning off the auto cruise traveling prohibition switch 93.

  FIG. 11 shows a flowchart of another example of control by the work vehicle control device of FIG. Even if the cruise control on / off switch 82 is pressed with the auto-cruise travel prohibition switch 93 turned on, if the auxiliary transmission lever 12 is on the high speed side, the control device 100 is controlled so as not to allow auto-cruise travel. . On the other hand, if the auxiliary transmission lever 12 is not on the high speed side, even if the auto cruise travel prohibition switch 93 is in the on state, if the cruise control on / off switch 82 is pressed, the auto cruise travel is performed.

  In addition, a parking brake sensor 105 that detects whether a parking brake lever (not shown) on the left side of the driver's seat 11 is turned on or off is provided at the rotation base of the parking brake lever, and the parking brake sensor 105 detects that the parking brake is turned on. If the HST pedal 9 is not in the neutral position when the forward / reverse lever 88 is in the forward or reverse side instead of the neutral position, a warning may be provided by a notification means such as a buzzer 95.

  Further, in addition to the notification means for stimulating hearing by sound such as a buzzer 95, a visual notification means such as displaying on a monitor (not shown) of the driver's seat 11 or lighting a lamp, an operator's operation tool A tactile notification means that gives vibration to a lever or the like is also conceivable.

If you forget to release the brake while driving (with the parking brake applied), the parking brake will be heavily loaded.
Therefore, when the user forgets to release the brake while pulling the parking brake, the operator can be alerted by the notification means such as the buzzer 95, thereby preventing the parking brake from being loaded.

  FIG. 12 shows a flowchart of another example of the control by the work vehicle control device of FIG. 1, and FIG. 13 shows another example of the block diagram of the control device of FIG. FIG. 13 is a diagram in which a parking brake sensor 105 and a buzzer 95 are added to the block diagram of FIG.

  As shown in FIG. 12, when the parking brake sensor 105 detects that the parking brake is engaged, the operation position of the forward / reverse lever 88 is detected by the forward / reverse lever sensor 73. When the operation position of the forward / reverse lever 88 is not the neutral position, that is, when it is in the forward side or the reverse side, the position of the HST pedal 9 is detected by the HST pedal position sensor 83. When the position of the HST pedal 9 is not the neutral position, that is, when it is depressed, the controller 100 controls the buzzer 95 to sound. On the other hand, when the HST pedal 9 is in the neutral position, the buzzer 95 is not sounded.

  If the work vehicle travels when the parking brake is engaged, a large load is applied to the parking brake.In this way, the alert means prompts the operator to be alerted, and the operator immediately notices and turns off the parking brake. Therefore, the parking brake can be prevented from being loaded.

  Further, when the parking brake is detected by the parking brake sensor 105 and when the forward / reverse lever 88 is not in the neutral position but in the forward side or the reverse side, the work vehicle is detected by the vehicle speed sensor 74. When the vehicle speed is not 0 (zero, stopped state), that is, when a traveling state is detected, a warning may be provided by a notification means such as a buzzer 95.

  FIG. 14 shows a flowchart of another example of control by the work vehicle control device of FIG. In the flow shown in FIG. 12, when the position of the HST pedal 9 is in the neutral position, control is performed by the control device 100 so that the buzzer 95 sounds. In the flow shown in FIG. 14, the vehicle speed of the work vehicle detected by the vehicle speed sensor 74 is controlled. When the value is not 0, the controller 100 controls the buzzer 95 to sound. Further, when the vehicle speed of the work vehicle detected by the vehicle speed sensor 74 is 0, there is no need for warning, so that the buzzer 95 is not sounded.

  Even in this configuration, when the user forgets to release the brake while pulling the parking brake, the operator is immediately aware of the parking brake by notifying the operator with a warning means such as a buzzer 95. Since it is turned off (brake is released), it is possible to prevent a load from being applied to the parking brake.

  In addition, an HST output shaft rotation sensor 86 for detecting the rotation speed (rpm) of the output shaft 27 of the hydrostatic continuously variable transmission (HST) 7 is provided, and the parking brake sensor 105 detects that the parking brake is engaged. When the forward / reverse lever 88 is not in the neutral position but in the forward side or the reverse side, the rotation speed of the output shaft 27 detected by the HST output shaft rotation sensor 86 is 0 (zero, not rotating) ), That is, when the rotational speed of the output shaft 27 is detected (a state where the output shaft 27 is rotating), a warning may be provided by a notification means such as a buzzer 95.

  FIG. 15 shows a flowchart of another example of control by the work vehicle control device of FIG. In the flow shown in FIG. 12, the control device 100 controls the HST pedal 9 to sound the buzzer 95 when the position of the HST pedal 9 is in the neutral position, but in the flow shown in FIG. 15, the rotation speed detected by the HST output shaft rotation sensor 86 is When it is not 0 (in a state where the output shaft 27 is rotating), the controller 100 controls the buzzer 95 to sound. Further, when the rotation speed detected by the HST output shaft rotation sensor 86 is 0, there is no need for a warning, so that the buzzer 95 is not sounded.

  Even in this configuration, when the user forgets to release the brake while pulling the parking brake, the operator is immediately aware of the parking brake by notifying the operator with a warning means such as a buzzer 95. Since it is turned off (releases the brake), it is possible to prevent the parking brake from being loaded.

  Further, when the parking brake is detected by the parking brake sensor 105 and the trunnion shaft 30 of the hydrostatic continuously variable transmission 7 is not in the neutral position, a warning may be given by a notification means such as a buzzer 95. .

FIG. 16 shows a flowchart of another example of control by the work vehicle control device of FIG. As shown in FIG. 16, when the parking brake sensor 105 detects that the parking brake is engaged, the operating position of the forward / reverse lever 88 is detected by the forward / reverse lever sensor 73. When the operation position of the forward / reverse lever 88 is not the neutral position, that is, when it is in the forward side or the reverse side, the position of the trunnion shaft 30 is detected by the trunnion sensor 70. When the position of the trunnion shaft 30 is not the neutral position, the controller 100 controls the buzzer 95 to sound. On the other hand, when the trunnion shaft 30 is in the neutral position, there is no need for warning, so the buzzer 95 is not sounded. The difference from the configuration of FIG. 12 is whether the rotation state of the HST pedal 9 is detected or the rotation of the trunnion shaft 30 is detected. Then, it is assumed that the forward / reverse lever 88 moves forward or backward. Forward-reverse levers 8 8 This is because not drive if neutral.

Although a large load on the parking brake when the work vehicle at the time of entering the parking brake will be traveling Ru Kaka, also in accordance with the present configuration, by prompting a warning to the operator by this way notifying means, the operator immediately Since the parking brake is turned off (the brake is released), it is possible to prevent a load from being applied to the parking brake.

  Further, in the flow shown in FIG. 16, when the trunnion shaft 30 is not in the neutral position, a warning is given by a notification means such as a buzzer 95. However, even if the trunnion shaft 30 is not in the neutral position, the predetermined time is reached. The buzzer 95 may not be sounded when the trunnion shaft 30 returns to the neutral position after a lapse.

  FIG. 17 shows a flowchart of another example of control by the work vehicle control device of FIG. As shown in FIG. 17, when the parking brake sensor 105 detects that the parking brake is engaged, the operation position of the forward / reverse lever 88 is detected by the forward / reverse lever sensor 73. When the operation position of the forward / reverse lever 88 is not the neutral position, that is, when it is in the forward side or the reverse side, the position of the trunnion shaft 30 is detected by the trunnion sensor 70. When the position of the trunnion shaft 30 is not a neutral position, measurement is performed for a predetermined time (in this example, 3 seconds) from the detection of the position of the trunnion shaft 30, and the buzzer 95 is not sounded until the predetermined time elapses. Control is performed by the control device 100 so that the buzzer 95 sounds. In other words, even if the position of the trunnion shaft 30 detected by the trunnion sensor 70 is not the neutral position, if it returns to the neutral position before the predetermined time has elapsed, there is no need for a warning, so that the buzzer 95 is not sounded. .

  When the parking brake is applied and the trunnion shaft 30 is not in the neutral position, if the buzzer 95 sounds immediately, the parking brake is turned off when the HST pedal 9 is stepped on when starting uphill, for example. Even when operated to the side (release of the parking brake), the buzzer 95 always sounds and the operator feels troublesome.

  However, when the position of the trunnion shaft 30 is not the neutral position as in this configuration, the notification means does not operate if the parking brake is operated to the cut side during that time by allowing a predetermined time until the notification. Therefore, there is no inconvenience that the buzzer 95 sounds even when starting up, such as uphill.

  On the other hand, when the trunnion shaft 30 is not in the neutral position even after the predetermined time has elapsed, the buzzer 95 is sounded, and the buzzer 95 sounds when the driver forgets to release the brake while the parking brake is on. A reminder is urged and the operator immediately notices and turns off the parking brake (releases the brake). Therefore, it is possible to prevent the parking brake from being loaded.

  Further, the parking brake sensor 105 detects that the parking brake has been applied, and the trunnion shaft 30 of the hydrostatic continuously variable transmission 7 is not in the neutral position, and the shift position of the sub-shift lever 12 is in the neutral position ( In cases other than (neutral), a warning may be provided by a notification means such as a buzzer 95.

  FIG. 18 shows a flowchart of another example of control by the work vehicle control device of FIG. As shown in FIG. 18, when the parking brake sensor 105 detects that the parking brake is engaged, the operation position of the forward / reverse lever 88 is detected by the forward / reverse lever sensor 73. When the operation position of the forward / reverse lever 88 is not the neutral position, that is, when it is in the forward or reverse side, the position of the trunnion shaft 30 is detected by the trunnion sensor 70. When the position of the trunnion shaft 30 is not the neutral position, the shift position of the auxiliary transmission lever 12 is further detected by the high-speed side auxiliary transmission lever sensor 65H and the low-speed side auxiliary transmission lever sensor 65L. When the shift position of the auxiliary transmission lever 12 is not the neutral position, that is, when it is at the high speed side or the low speed side, the control device 100 controls the buzzer 95 to sound. On the other hand, when the shift position of the auxiliary transmission lever 12 is the neutral position, there is no need for a warning, so that the buzzer 95 is not sounded.

But when the work vehicle at the time of entering the parking brake will be running a large load on the parking brake Ru Kaka, by prompting the warning to the operator by this way notification means, the parking brake worker noticed immediately Since it is turned off (brake is released), it is possible to prevent a load from being applied to the parking brake.

  The present invention is applicable to a work vehicle equipped with a hydraulic continuously variable transmission.

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Front wheel 3 Engine 5 Cockpit 6 Rear wheel 7 Hydrostatic continuously variable transmission 7a Variable displacement hydraulic pump 7b Constant displacement hydraulic motor 7c Hydraulic input shaft 8 Brake pedal 9 HST pedal 10 Lifting link device 11 Driver's seat 12 Sub-transmission lever 14 Transmission case 15 Front case 16 Connection case 17 Intermediate case 18 Rear case 19 Input shaft 20 Input cases 21, 22, 24, 25 Gear 23 First relay shaft 26 PTO drive shaft 27 Output shaft 28 Drive shaft 29, 31 gear 30 trunnion shaft
32 Counter shaft after PTO 33 Counter gear 34 PTO clutch 35 Counter shaft before PTO 37 Front wheel drive gear 40 Transmission shaft 40a, 40b, 40c Gear 41 Main transmission shaft (clutch shaft) 42 Large gear
43 Medium gear 44a Sub-transmission high-speed small gear 44b Sub-transmission low-speed large gear 45 Clutch shafts 46, 47 Transmission clutch gear 48a Sub-transmission high-speed large gear 48b Sub-transmission low-speed small gear 49 High-speed hydraulic clutch solenoid 50 Low-speed hydraulic pressure Clutch solenoid 51 High speed side hydraulic clutch 52 Low speed side hydraulic clutch
53 Differential gear 56 Rear wheel drive gear 57 Counter gear 58 Gear 60 Rear wheel output gear 61 Rear wheel drive shafts 62a, 62b Main transmission (high / low switching) switches 63a, 63b Main transmission clutch sensor (high speed side / low speed side)
64 Lever guide 65H, 65L Sub-shift lever sensor 66 Trunnion shaft drive motor 70 Trunnion sensor 73 Forward / reverse lever sensor 74 Vehicle speed sensor 82 Cruise control on / off switch 83 HST pedal position sensor 86 HST output shaft rotation sensor 88 Forward / reverse lever 89 Clutch pedal 90 Cruise control memory switch 92 Brake pedal sensor 93 Auto cruise travel prohibition switch 95 Buzzer 100 Controller (controller) 101 Accelerator lever 103 Engine speed sensor 105 Parking brake sensor

Claims (3)

Engine (3),
Engine rotation speed setting means (101) for setting the rotation speed of the engine (3) to a constant rotation speed;
Engine speed detecting means (103) for detecting the speed of the engine (3);
A trunnion shaft (30) for changing the inclination angle of the swash plate for inputting the power of the engine (3) and adjusting the output hydraulic pressure, and the hydraulic pressure corresponding to the rotation angle of the trunnion shaft (30) A hydrostatic transmission (7) that outputs an output rotational speed based on
A trunnion shaft drive motor (66) for rotating the trunnion shaft (30);
A transmission comprising a main transmission and a sub-transmission for shifting the output rotational speed from the hydrostatic transmission (7);
A traveling device (2, 6) in which power from the engine (3) is transmitted via the hydrostatic transmission (7) and the transmission;
Main shift operation means (62a, 62b) for operating the main shift by the main transmission to the low speed side and the high speed side;
Main shift operation detecting means (63a, 63b) for detecting a main shift by operation of the main shift operation means (62a, 62b);
Sub-shift operation means (12) for operating the sub-shift by the sub-transmission device to the low speed side and the high speed side;
Sub-shift operation detecting means (65H, 65L) for detecting a sub-shift by operation of the sub-shift operation means (12);
An HST pedal (9) for adjusting the rotation angle of the trunnion shaft (30) of the hydrostatic transmission (7) via a trunnion shaft drive motor (66) in accordance with the depression amount;
HST pedal detection means (83) for detecting the depression amount of the HST pedal (9);
Operation means (82) for auto cruise traveling for keeping the traveling speed of the traveling device (2, 6) constant;
Auto cruise travel prohibiting operation means (93) for prohibiting auto cruise travel by the auto cruise travel operation means (82);
When the auto-cruise driving operation means (82) is operated, the rotation angle of the trunnion shaft (30) corresponding to the depression amount of the HST pedal (9) detected by the HST pedal detection means (83) at that time. The trunnion shaft drive motor (66) is controlled so as to maintain the first auto-cruise function that keeps the traveling speed of the traveling devices (2, 6) constant, and during the traveling by the first auto-cruise function. And when the main shift detected by the main shift operation detecting means (63a, 63b) is on the low speed side and the sub shift detected by the sub shift operation detecting means (65H, 65L) is on the high speed side, Whether the engine speed detected by the engine speed detecting means (103) is a constant speed set by the engine speed setting means (101). A function of releasing the first auto-cruise function and falls by more than a predetermined value, the subtransmission operation detecting means (65H, 65L) auto-cruise traveling prohibiting operation means when the subtransmission detected by is high side (93) The first auto-cruise function is disabled while the automatic shift running prohibiting operation means (93) is activated when the auxiliary shift detected by the auxiliary shift operation detecting means (65H, 65L) is not on the high speed side. Even in the on state, when the first auto-cruise function is enabled and the auto-cruise traveling prohibition operation means (93) is operated to be turned off, the sub-shift operation detection means (65H, 65L) detects it. controller having an auto-cruise traveling prohibited acceptable function subtransmission can be a high-speed side to enable the first automatic cruise function ( 00) and the work vehicle, characterized in that it comprises a. An auto cruise travel speed reproduction operation means (90) for reproducing the speed at the previous auto cruise travel is provided,
The control device (100) is the sub-shift operation detecting means when traveling by the first auto-cruise function and the main shift detected by the main shift operation detecting means (63a, 63b) is on the low speed side. When the sub-shift detected by (65H, 65L) is on the high speed side, the engine speed detected by the engine speed detecting means (103) is set by the engine speed setting means (101). The first auto-cruise function is canceled when the rotational speed is reduced by a predetermined value or more from a certain rotational speed, and the trunnion shaft (30) of the hydrostatic transmission (7) is neutralized from the position during travel by the first auto-cruise function. The trunnion shaft drive motor (66) is controlled so as to return to the half position on the side and maintain the half position on the neutral side. The running speed of 2,6) have a second auto-cruise function of keeping constant, further, the said auto-cruise traveling speed reproduction operation means (90) is operated during the running by the first automatic cruise function hydrostatic The trunnion shaft (30) of the automatic transmission (7) is changed to the position at the time of the previous auto-cruise travel, but when the travel by the first auto-cruise function is not performed, the auto-cruise travel speed reproduction operation means (90) according to claim 1 but also is operated, characterized in that chromatic autocruise traveling speed reproduction function that does not change the trunnion shaft (30) to the position of the previous auto-cruise traveling of the hydrostatic transmission (7) Work vehicle.   In the control device (100), the engine speed detected by the engine speed detecting means (103) is set by the engine speed setting means (101) when traveling by the second auto cruise function. A function of controlling the trunnion shaft drive motor (66) so as to return the trunnion shaft (30) of the hydrostatic transmission (7) to the position during traveling by the first auto-cruise function. The work vehicle according to claim 2, further comprising:

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