JP2013244950A - Working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a travelling vehicle capable of safe backward travelling by automatically releasing automatic cruise when a forward/backward lever 10 is operated to a backward side.SOLUTION: A travelling vehicle is provided with a forward/backward lever position sensor 10a for detecting an operating position of a forward/backward lever 10; an automatic cruise switch 14c for adjusting hydraulic output of HST 34 by varying a rotational angle of a trunnion shaft 30 by responding to the stepped in amount for keeping the travelling speed of travelling wheels 2, 3 constant; and a controller 100 with a control structure for releasing the automatic cruise travelling when the forward/backward lever position sensor 10a detects that the forward/backward lever 10 is in the backward side even when the automatic cruise switch 14c is in action. In this case, no possibility exist of the vehicle travelling backward in backward even when a switching operation occurs for forward/backward which is frequently carried out for a working vehicle.

Description

  The present invention relates to a work vehicle such as a tractor for agriculture, construction, and transportation.

  When a work vehicle such as a tractor is turned 180 degrees, the auto-cruise traveling is canceled when the steering wheel is operated or the rotary is raised.

JP-A-1-168530

In the work vehicle of Patent Document 1, etc., when the traveling direction is largely corrected from the forward side to the reverse side, the forward / reverse lever is operated to the reverse side. As a result, there was a longer distance to move forward due to the inertial force during reverse operation, and this resulted in a poor response to reverse travel. Further, if the auto cruise is not canceled, the vehicle is accelerated to the auto cruise speed when the reverse drive is applied, so that the safe reverse may not be performed.
An object of the present invention is to provide a traveling vehicle in which auto-cruise is automatically canceled when the forward / reverse lever is operated to the reverse side so that the vehicle can travel backward safely.

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 (5), the engine speed detecting means (5a) for detecting the speed of the engine (5), and the power of the engine (5) are inputted, and the hydraulic pump (34a ), The trunnion shaft (30) having a swash plate (34d) that can change the inclination angle provided in the hydraulic pump (34a), and hydraulic oil corresponding to the inclination angle of the swash plate (34d) (34c) to the hydraulic motor (34b), and the hydraulic motor (34b) drives the travel output shaft (36), and the hydraulic continuously variable transmission (34). A gear-engaged, multiple-stage auxiliary transmission (38) that is operated by an output; traveling wheels (2, 3) that are driven by the output of the auxiliary transmission (38); and a forward direction of the trunnion shaft (30) or Runs at a reverse rotation angle A forward / reverse lever (10) for switching the forward or reverse rotation of the wheel (2, 3), a forward / reverse lever position sensor (10a) for detecting the operation position of the forward / reverse lever (10), and a depression An accelerator pedal (15) that changes the output amount of the HST 34 by changing the rotation angle of the trunnion shaft (30) corresponding to the amount, and provided at the base of the accelerator pedal (15), the accelerator pedal (15) And an swash plate fixed to the trunnion shaft (30) of the hydraulic continuously variable transmission (34) according to the detected value of the accelerator pedal sensor (15a). A trunnion hydraulic proportional valve (65) for adjusting the hydraulic output of the hydraulic continuously variable transmission (34) by adjusting the forward or reverse inclination angle of (34d), and the auxiliary transmission (38 Sub-shift operation means (21) for operating the sub-shift by the low speed side and the high speed side, and auto-cruise travel operation means (auto-cruise switch) for keeping the travel speed of the traveling wheels (2, 3) constant ( 14c) and the forward / reverse lever position sensor (10a) detects that the forward / reverse lever (10) is on the reverse side, the automatic cruise traveling is canceled even if the operation means (14c) for the automatic cruise traveling is in operation. A traveling vehicle is provided with a control device (100) having a control configuration.

  According to the second aspect of the present invention, the accelerator pedal detecting means (15a) for detecting the depression amount of the accelerator pedal (15), and the amount of operation of the accelerator pedal (15) during the auto-cruise traveling control is not more than a predetermined value (for example, 7%), then the accelerator pedal detection means (15a) detects that the accelerator pedal (15) is further depressed and the accelerator pedal detection means (15a) exceeds a predetermined value (about half of the predetermined value, for example, 2. The traveling vehicle according to claim 1, wherein the control device (100) is provided with a control configuration for canceling the auto-cruise traveling when it is detected that the total is approximately 12%.

  According to a third aspect of the present invention, the control device (100) has a control configuration in which the auto-cruise traveling control is canceled when the engine speed detecting means (5a) detects that the engine speed is less than a predetermined value (eg, less than 500 rpm). The traveling vehicle according to claim 1, wherein the traveling vehicle is provided.

  According to the fourth aspect of the present invention, the vehicle speed detecting means (53) for detecting the rotational speed of the traveling wheels (2, 3) and the brake switches (77a, 77b) for detecting the depression of each of the brake pedals (16, 16). ) And a vehicle speed slow response dial (14b) for setting the rotation angle of the trunnion shaft (30) of the hydraulic continuously variable transmission (34) to a vehicle speed slow response speed, and operating means for auto-cruise traveling (auto-cruise switch) When the auto cruise is released with (14c) turned off, the vehicle speed detection means (53) detects that the vehicle speed is on the deceleration side, the brake switches (77a, 77b) are on, and the vehicle speed slow response. When the dial (14b) is set below the standard value, the control configuration for forcibly returning the set value of the vehicle speed slow response dial 14b to the standard value or the vehicle speed slow When the answer dial (14b) is set below the standard value, the forward / reverse lever sensor (10c) indicates that the forward / reverse lever (10) is reversely operated from the forward side to the reverse side or from the reverse side to the forward side. When the reversal operation time between the forward side and the reverse side is shorter than a predetermined value, the control device (100) is configured to decelerate the vehicle speed slow response dial (14b) to a standard value. The traveling vehicle according to claim 1, wherein the traveling vehicle is provided.

  According to the first aspect of the present invention, if the automatic cruise is not canceled when the forward / reverse lever 10 is operated from the forward side to the reverse side, the reverse travel is performed at the speed of the auto cruise. In order to avoid this, it is possible to work on a tractor or the like by adopting a control configuration that releases auto-cruise when the forward / reverse lever 10 is operated from the forward side to the reverse side during auto-cruise traveling control. Even if there is a forward / reverse switching operation frequently performed in the vehicle, there is no possibility that the vehicle travels backward during reverse travel.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, when the amount of depression of the accelerator pedal 15 becomes smaller than a predetermined value over two stages, the traveling vehicle is decelerated and the auto cruise is performed. You can drive safely by canceling it so that no unexpected situation occurs.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, when the engine speed becomes a predetermined value or less, the auto-cruise traveling is automatically canceled, so that safe traveling can be performed.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 1, when the vehicle speed slow response dial 14b is set to a standard value or less, control for slowly moving the trunnion shaft 30 of the HST 34 is performed. Even if the accelerator pedal 15 is operated, it takes time to reach the target speed. At this time, when the auto cruise is canceled and the vehicle is on the deceleration side, the vehicle is slowly decelerated because of the setting. Canceling auto-cruise basically wants to decelerate early, so only for such decelerating, even if the vehicle speed slow response dial 14b is set to a standard value or less, the trunnion shaft 30 of the HST 34 is moved from the standard speed. Decelerate quickly by moving fast. Further, the fact that the reverse operation time between the forward side and the reverse side is shorter than a predetermined value is the same as described above because the forward / reverse lever 10 is operated at high speed.

It is a side view of the tractor of the Example of this invention. It is a top view of the tractor of FIG. It is a power transmission mechanism diagram of the transmission of the tractor of FIG. FIG. 2 is a hydraulic circuit diagram of the hydrostatic continuously variable transmission of the tractor of FIG. 1. It is a control block diagram of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG. It is a flowchart of control of the tractor of FIG.

Embodiments of the present invention will be described with reference to the drawings.
Hereinafter, a tractor will be described as an example of a work vehicle. FIG. 1 (FIG. 1 shows a view without a front loader) shows an overall side view, and FIG. 2 shows a plan view of the tractor of FIG. 1 (excluding the cabin). 3 is a power transmission mechanism diagram of the tractor transmission of FIG. 1, FIG. 4 is a hydraulic circuit diagram of the hydrostatic continuously variable transmission of the tractor of this embodiment, and FIG. 5 is a control of the tractor of this embodiment. It is a block diagram.
In this specification, the left and right directions in the forward direction of the work vehicle are referred to as left and right, respectively, the forward direction is referred to as front, and the reverse direction is referred to as rear.

The tractor shown in FIGS. 1 and 2 includes front wheels 2 and 2 and rear wheels 3 and 3 at the front and rear portions of the traveling vehicle body 1, and the rotational power of the engine 5 mounted on the front portion of the vehicle body 1 is transmitted by a transmission in the transmission case. The vehicle is configured to be appropriately decelerated and transmitted to the front wheels 2 and 2 and the rear wheels 3 and 3.
A steering handle 7 is supported on the handle post 6 in the center of the vehicle body 1, and a seat 9 is provided behind the steering handle 7.

As shown in FIG. 1, the fuel tank 8 is stored in the bonnet 22, and the rear side of the fuel tank 8 main body is stored in the handle post 6.
A forward / reverse lever 10 that switches the traveling direction of the vehicle body 1 to the front / rear direction is provided below the steering handle 7. When the forward / reverse lever 10 is moved forward, the vehicle body 1 moves forward, and when it is moved backward, it moves backward. A throttle lever 11 for changing the engine speed is provided on the opposite side of the forward / reverse lever 10 with the handle post 6 in between. An accelerator pedal 15 and left and right brake pedals 16 are provided at the right corner of the step floor 13. , 16 are arranged. The accelerator pedal 15 is basically used when traveling on the road, the engine speed increases according to the amount of depression, and the amount of depression of the accelerator pedal 15 is detected by an accelerator pedal position sensor 15a (FIG. 5). The rotation angle of the trunnion shaft 30 (FIG. 4) of the hydrostatic continuously variable transmission (HST) 34 can be changed by the trunnion hydraulic proportional valve 65 in accordance with the detected value of the accelerator pedal position sensor 15a. By changing the inclination angle of the swash plate 34d (FIG. 4) according to the rotation angle of the trunnion shaft 30, the output of the HST can be continuously changed steplessly.

  The throttle lever 11 is used to change the engine speed and is used during work travel. The throttle lever 11 is configured so that the position is maintained even if the hand is released at the operated position. Further, a sub-shifting lever 21 that can select any of low speed, medium speed, high speed, and neutral position is arranged on the left side of the cockpit 9 and is mounted behind the front wheel 2 and the rear wheel 3 behind the mid work. A mid PTO speed change lever 23a for turning on and off the PTO shaft of a machine (moor etc.) and a PTO shaft on and off of a working machine (mower, rotary, snowplow etc. (not shown)) mounted on the rear part of the machine body. A rear PTO speed change lever 23b is provided. A link 31 for connecting a work machine (not shown) is provided behind the vehicle body 1.

  The rotational power of the engine 5 is transmitted from the HST input shaft 33 to the HST 34. Further, the hydraulic pump 34a shown in FIG. 4 is operated by the power introduced from the HST input shaft 33, and pressure oil corresponding to the inclination angle of the swash plate 34d provided in the hydraulic pump 34a is supplied from the hydraulic closed circuit 34c to the hydraulic motor. The driving output shaft 35 is driven by the hydraulic motor 34b to transmit power to the meshing transmission 38.

As shown in FIG. 3, in the auxiliary transmission clutch shifter 39 of the meshing transmission 38, the rotation of the transmission shaft 43 is driven through the differential device 46 and the rear wheel 3 is driven at the traveling speed of the auxiliary transmission high speed stage.
The power output from the HST 34 is transmitted from the travel output shaft 35 to the rotary shaft 36. The gear position by the transmission 38 is set as follows. That is, in the sub-speed stage (third speed), the power changed by the gear 38 b from the gear 38 a is transmitted to the transmission shaft 43. In addition, in the sub-speed middle speed (second speed), the power shifted from the gear 38c by the gear 38d is transmitted to the transmission shaft 43, and in the sub-speed lower speed (first speed), the gear 38e is shifted by the gear 38f. Power is transmitted to the transmission shaft 43. These three sub-shifts are switched by operating the sub-shift lever 21 and sliding the shifter 39 left and right. The rotation of the transmission shaft 43 is driven through the differential device 46 so that the rear wheel 3 is driven at the traveling speed of the sub-shift middle speed.

On the other hand, power input from the HST input shaft 33 to the variable displacement hydraulic pump 34a (FIG. 4) is provided to the PT46O shaft 52 from the pump output shaft 51 (shown only in FIG. 3) via the PTO hydraulic clutch 54 and the like. Is transmitted to the drive system for the PTO. Power is transmitted to the rear PTO shaft 55 and the mid PTO shaft 56 to the PTO shaft 52.
Also, the gear 58 on the lower side of the sub-shift of the transmission shaft 43 is transmitted to the gear 57 of the front wheel output shaft 48 via the gear 47 of the PTO shaft 52 and the gear 59 integral with the gear 47, and the front wheel 2 is driven. The

Further, when a loader (not shown) is attached to the front or rear of the vehicle body 1, the loader is raised and lowered by a loader lifting cylinder (not shown).
The hydrostatic continuously variable transmission (HST) 34 has a rotational speed of the trunnion shaft 30 set by the control device 100 according to the rotational angle of the trunnion shaft 30 (FIG. 4), that is, the rotational angle of the swash plate 34d. Although the detailed description is omitted, when the depression amount of the accelerator pedal 15 is detected by the accelerator pedal position sensor 15a, the operation amount (the number of rotations) of the trunnion shaft 30 according to the detected value of the accelerator pedal position sensor 15a. Is automatically set by the control device 100 by the trunnion hydraulic proportional valve 65, and the hydraulic pressure output of the hydrostatic continuously variable transmission (HST) 34 is automatically set to an appropriate value.

  In addition, the control device 100 operates the hydrostatic continuously variable transmission by a method such as operating a changeover switch (not shown) provided at the rotation base of the forward / reverse lever 10 by switching the forward / reverse lever 10 to the forward side or the reverse side. The rotation direction of the trunnion shaft 30 of the device (HST) 34 is set to the forward side or the reverse side. The turning direction of the trunnion shaft 30 is determined by the switching valve 63 (FIG. 4). Then, the rotation angle of the trunnion shaft 30 changes according to the depression amount of the accelerator pedal 15. The rotation angle of the trunnion shaft 30 is determined by the amount of current to the solenoid valve of the trunnion hydraulic proportional valve 65.

  Further, in the event of an emergency such as a valve stick, the HST trunnion shaft 30 can be forcibly returned to neutral by fully depressing the brake pedals 16 and 16 in the control section. When the brakes 16 and 16 are stepped on, the operator removes his / her foot from the accelerator pedal 15, so the trunnion shaft 30 returns to neutral. At this time, whether the trunnion shaft 30 returns naturally or forcibly returns at a high speed differs depending on the model.

  In the hydraulic circuit 34c of the HST 34 shown in FIG. 4, when a valve or the like is clogged with impurities (valve stick), an emergency stop lever (not shown) in the control section is pulled to return the trunnion shaft 30 of the HST 34 to neutral. .

  As shown in the overall plan view of the tractor shown in FIG. 1, a throttle lever 11 and a forward / reverse lever 10 are arranged on the left and right on the handle post 6 around the handle 7. An accelerator pedal 15 is disposed on the step floor 13 on the right side of the throttle lever 11. The accelerator pedal 15 can adjust the rotation angle of the trunnion shaft 30 of the HST 34.

Furthermore, the lever guide 12a on the right side of the cockpit 9 has a maximum speed setting dial 14a, a vehicle speed slowness response dial 14b, and a cruise travel switch 14c arranged in a line in order from the front side to the rear side. The dials 14a and 14b and the switch 14c need only be arranged in a line in the front-rear direction, and the arrangement order of the dials 14a and 14b and the switch 14c is not particular.
The maximum speed setting dial 14a is a dial type, and regulates the maximum speed of the vehicle body by adjusting the rotation angle of the trunnion shaft 30. For example, the maximum speed setting dial 14a is set so that the operator can determine a predetermined maximum speed. It is set as the structure which can be changed into a dial type in the range of 15-30 km / h. Therefore, even if the accelerator pedal 15 is depressed to the maximum, only the speed regulated by the maximum speed setting dial 14a can be obtained.

  The vehicle speed slowness response dial 14b also changes and sets the rotation speed of the trunnion shaft 30. When the accelerator pedal 15 is stepped on, the target speed of the accelerator pedal sensor 15a, that is, the rotation angle of the target trunnion shaft 30 is determined. The trunnion shaft is reached by the position of the rotation angle of the target trunnion shaft 30. The time which 30 reaches | attains is changed. For example, if the vehicle speed slowness response dial 14b is made insensitive (slow), even if the accelerator pedal 15 is stepped on quickly, the time to reach the target rotation angle of the trunnion shaft 30 will be slow, so it will accelerate slowly. It is the composition which goes. The change of the arrival time to the target position is performed by changing the duty ratio of the current to the trunnion hydraulic proportional valve 65 (FIG. 4). The time until the vehicle speed slowness response dial 14b reaches a predetermined vehicle speed can be changed to a dial type from about 3 seconds to about 6 seconds, for example.

  The cruise travel switch 14c is an on / off switch. If the cruise travel switch 14c is turned on while traveling at a specific speed, the speed at that time is maintained even if the accelerator pedal 15 is released. It is a configuration. That is, the cruise travel switch 14c keeps the rotation angle of the trunnion shaft 30 constant so as to match the vehicle speed when the cruise travel switch 14c is turned on, so the output of the HST 34 is kept constant and the vehicle speed is kept constant. Is done. Even if the foot is released from the accelerator pedal 15 after the cruise travel switch 14c is turned on, the speed at that time is maintained.

  In this way, the turning angle of the trunnion shaft 30 of the HST 34 can be set to any one of the three preset types by simply turning on the highest speed setting dial 14a, the vehicle speed slowness response dial 14b, or the cruise travel switch 14c. Since it can be set, the maneuverability is improved as compared with the case where these dials 14a and 14b and the switch 14c are not provided. In addition, since the dials 14a and 14b and the switch 14c are arranged in a line in the front-rear direction adjacent to the cockpit 9, the selection of the dials 14a and 14b and the switch 14c is not lost, and the target dial and switch Can be put in quickly.

  The dials 14a and 14b and the switch 14c are collectively called a servo switch, but the highest speed setting is set from the front side to the rear side in order to line up the right lever guide 12a adjacent to the cockpit 9 in the front-rear direction. You may arrange | position in order of the dial 14a, the cruise travel switch 14c, and the vehicle speed slowness response dial 14b.

Further, on the left side of the cockpit 9, an auxiliary transmission lever 21, a mid PTO lever 23a, a rear PTO lever 23b, and a 4WD lever 24 are arranged. The sub-transmission lever 21 is disposed outside the 4WD lever 24, and the mid PTO lever 23a is disposed outside the rear PTO lever 23b.
In an emergency such as a valve stick, the HST trunnion shaft 30 can be forcibly returned to neutral by fully depressing the brake pedals 16 and 16 in the control section shown in FIG.

  In the tractor with HST servo, when the operation position of the throttle lever 11 detected by the throttle lever sensor 11a is in the vicinity of the half throttle position (when the engine speed is about half of the maximum speed), When it is determined that a load is placed in a bucket of a loader (not shown) that can be moved up and down, and the forward / reverse lever 10 is on the forward side (the rotation direction of the trunnion shaft 30 is forward) The throttle lever 11 is left as it is, and the engine speed is kept constant and the accelerator pedal 15 is depressed to increase the hydraulic output of the HST 34 to increase only the vehicle speed, but the forward / reverse lever 10 is on the reverse side. In this case, the rotation speed corresponds to the rotation angle of the trunnion shaft 30 corresponding to the depression amount of the accelerator pedal 15, and the die By varying in speed slower response speed slower than the speed change rate set by Le 14b, it may be performed gently raising control vehicle speed.

  Further, the turning angle of the trunnion shaft 30 is increased by depressing the accelerator pedal 15, and the engine speed is increased when the accelerator pedal 15 is further depressed even if the engine speed becomes equal to or higher than the half throttle. The vehicle speed is increased by increasing the operation amount of the trunnion hydraulic proportional valve 65 for adjusting the rotation angle of the trunnion shaft 30 controlled by the controller 100 according to the depression amount of the accelerator pedal 15.

  By controlling the engine speed as described above, fuel efficiency can be reduced in the half throttle state. In particular, when the vehicle is traveling backward, by gradually increasing the engine speed, the engine driving force can be reduced and fuel consumption can be reduced.

  Further, the arrival speed to the target speed can be changed according to the forward / reverse switching speed of the forward / reverse lever 10 detected by the forward / backward lever switching speed sensor 10a provided at the base of the forward / backward lever 10. For example, when the forward / reverse lever 10 is switched quickly in consideration of the operator's intention, the time to reach the target speed can be shortened.

  In addition, a control configuration that can change the speed to reach the target speed according to the forward / reverse switching speed of the forward / reverse lever 10 (considering the operator's intention according to the forward / backward switching speed of the forward / backward lever 10). In addition, when switching forward and reverse quickly, the time to reach the target speed is shortened), and at this time, the switching speed from reverse to forward is compared to the switching speed from forward to reverse And increase the time to reach the target speed. This is to prevent the operator from feeling afraid of switching from backward to forward.

In the tractor with HST servo, the switching speed from reverse to forward is switched from reverse to reverse at the same time as control for changing the speed to reach the target speed in accordance with the forward / backward switching speed of the forward / reverse lever 10. By making it slower than the speed so that the speed to reach the target speed becomes slower, the fear of the operator is eliminated, and further, the detected value of the HST output shaft rotation sensor 35a and the detected value of the trunnion shaft rotation angle sensor 30a. (The difference between the two detected values from the predetermined value) is determined to determine the traction load of the work implement, and the output change speed of the hydrostatic continuously variable transmission 34 is adjusted according to the traction load. Thus, work such as loader work can be easily performed. For example, if it is determined that the load of the loader (not shown) is filled with earth and sand by judging the tractor's traction load, it will move back and forth more slowly than when there is no earth or sand so as not to drop the earth and sand from the loader bucket. Adopting a control configuration that switches between hexes.
This control configuration is also performed to prevent the operator from feeling afraid of switching from backward to forward.

If the difference between the detected values of the trunnion shaft rotation angle sensor 30a and the HST output shaft rotation sensor 35a deviates from a predetermined value, it is determined that the tractor has a traction load, and the feedback speed can be changed. .
Normally, the trunnion shaft rotation angle and the HST output shaft rotation speed are proportional to each other. However, depending on the travel load, even if the trunnion shaft rotation angle is constant, the HST output shaft rotation speed changes when a load is applied. When the engine speed is constant, the change in the engine speed is read, and the change speed of the trunnion hydraulic proportional valve 65 is adjusted according to the amount of change per time. For example, if the change speed of the HST trunnion hydraulic proportional valve 65 (FIG. 4) is made slow, the vehicle speed can also be lowered slowly.
FIG. 5 shows a control block diagram of the tractor control device of this embodiment.

  In addition, when the traction load of the tractor is determined and the feedback speed is changed based on the deviation between the trunnion shaft rotation angle sensor 30a and the HST output shaft rotation sensor 35a, the traction load of the tractor is not changed. When the engine speed decreases due to the PTO load, it is determined that there is a PTO load, and the vehicle speed is controlled to be reduced to prevent engine stall due to the PTO load.

Further, since the traction load of the tractor is judged based on the deviation between the trunnion shaft rotation angle sensor 30a and the HST output shaft rotation sensor 35a, the traction load does not change and the throttle lever 11 is not operated. When there is no detection of the movement of the throttle lever 11 by 11a and the engine speed varies due to the PTO load, the change speed of the HST trunnion hydraulic proportional valve 65 is adjusted to lower the vehicle speed.
This is to prevent the engine stall when the engine drop occurs due to the PTO load during traveling at a constant vehicle speed during the PTO operation.

  Further, the deviation of the trunnion shaft rotation angle sensor 30a and the HST output shaft rotation sensor 35a and the variation of the engine speed are comprehensively determined (detection values of the trunnion shaft rotation angle sensor 30a and the HST output shaft rotation sensor 35a). If the engine speed is low and the engine speed is low, it is determined that the load is large, and even if the detected values of the trunnion shaft rotation angle sensor 30a and the HST output shaft rotation sensor 35a are misaligned, If the number has not decreased, there may be a problem due to the structure of the mechanical member, not the load), and the change speed of the trunnion hydraulic proportional valve 65 is adjusted by sensing both the tractor traction load and the PTO load fluctuation. Thus, a control configuration for changing the vehicle speed may be adopted.

Thus, it is possible to prevent engine stall by detecting fluctuations in the PTO load and the traction load and reducing the vehicle speed in accordance with the load.
The electronically controlled HST 34 of the present embodiment may be configured such that the inclination angle of the swash plate 34d of the trunnion shaft 30 of the HST 34 can be switched between the two-stage specifications of the low speed side and the high speed side.

  As shown in FIG. 4, a swash plate 34d is provided on the pump 34a side of the HST 34, and the swash plate 34d can change the tilt angle, and is generally referred to as a variable pump 34a. On the other hand, there is generally no swash plate on the side of the motor 34b, which is referred to as a quantitative motor 34b. In this way, when the quantitative motor 34b without the stage switching function of the HST 34 described below is used, the stage is fixed. Since this fixing varies depending on the model, it is usually high speed, high speed vicinity, or high speed and low speed. Such as the middle.

  A motor 34b having a swash plate 34e on the motor 34b side is referred to as a variable motor 34b. In the present embodiment, a configuration may be adopted in which a swash plate 34e is provided also on the motor 34b side and control for moving the swash plate 34e can be performed. The output of the variable motor 34b is switched between two stages of high speed and low speed. This is called stage switching of the variable motor 34b having the swash plate 34e.

  The two-stage specification of the low speed side and the high speed side is performed by changing the angle of the swash plate 34e of the variable hydraulic motor 34b, and cannot be performed by the variable hydraulic pump 34a. The rotation angle of the swash plate 34d of the variable hydraulic pump 34a changes according to the depression amount of the speed change pedal 15.

  As a characteristic of the HST 34, the torque does not change even if the speed is changed by changing the inclination angle of the swash plate 34d on the pump 34a side, and the torque fluctuation occurs only when the engine speed is changed. However, if the speed is changed by changing the inclination angle of the swash plate 34e on the motor 34b side, the torque also changes, and the torque increases at a low speed, and decreases at a high speed.

  When the engine load increases and the engine speed decreases, the torque increases as the output speed of the HST 34 decreases by changing the inclination angle of the swash plate 34e on the motor 34b side to lower the HST stage. The engine stall can be prevented and stable work can be performed. At this time, even if the swash plate 34d on the pump 34a side is moved to the low speed side, the torque does not increase, so that a stable driving force cannot be obtained.

  Thus, the torque changes by changing the traveling speed of the vehicle by changing the rotation angle of the swash plate 34e of the variable hydraulic motor 34b. However, the torque does not change even if the speed is changed by the variable hydraulic pump 34a. This is a feature of the step transmission 34, and the present invention utilizes the feature point of the HST 34.

  The output of the hydrostatic continuously variable transmission (HST) 34 is determined by the rotation angle of the trunnion shaft 30 and will not be described in detail, but according to the detection value of the accelerator pedal position sensor 15a as described above. The operation amount of the trunnion shaft 30 is automatically set by the control device 100 by the trunnion hydraulic proportional valve 65, and the hydraulic output of the hydrostatic continuously variable transmission (HST) 34 is automatically set to an appropriate value.

  It should be noted that the forward / reverse switching lever 10c is switched to the forward side or the reverse side, based on a detection value of a potentiometer 10c (shown only in FIG. 5) provided at the rotation base of the forward / backward switching lever 10, or the forward / reverse switching switch 10a. , 10b (shown only in FIG. 5) or the like, the control device 100 sets the rotational direction of the trunnion shaft 30 of the hydrostatic continuously variable transmission (HST) 34 to the forward side or the reverse side. The turning direction of the trunnion shaft 30 is determined by the switching valve 63 (FIG. 4). Then, the rotation angle of the trunnion shaft 30 changes according to the depression amount of the accelerator pedal 15. The rotation angle of the trunnion shaft 30 is determined by the amount of current to the trunnion hydraulic proportional valve 65.

  Further, in the event of an emergency such as a valve stick, the HST trunnion shaft 30 can be forcibly returned to neutral by fully depressing the brake pedal 16 in the control section.

  As described above, the hydraulic output of the hydrostatic continuously variable transmission (HST) 34 is changed by the trunnion hydraulic proportional valve 65 according to the depression amount of the accelerator (HST) pedal 15, and the rotation angle of the trunnion shaft 30 of the HST 34 is changed. And the output of the HST 34 is changed steplessly by changing the inclination angle of the swash plate 34d provided on the trunnion shaft 30, but the accelerator pedal sensor 15a for detecting the depression amount of the accelerator (HST) pedal 15 is used. If there is an abnormality, the operation panel 9b displays that there is some abnormality in the accelerator (HST) pedal 15 on the display screen by appropriate graphics, characters, voices, or the like.

  Further, when the value of the pedal sensor 15a of the accelerator pedal 15 is out of the specified range during auto-cruise traveling, the control oil pressure of the trunnion hydraulic proportional valve 65 is changed from the operation amount of the accelerator pedal 15, and the accelerator pedal 15 is placed on the operation panel 9b. Fail-safety can be achieved by outputting an indication of any abnormality on the display screen using appropriate graphics, characters, voices, etc., and canceling the auto cruise control.

  In the abnormal processing of the accelerator pedal sensor 15a that regulates the output from the operation amount of the accelerator pedal 15 to the solenoid valve (solenoid) of the trunnion hydraulic proportional valve 65, when the sensor value is out of the prescribed range during auto-cruise control, the accelerator pedal 15 In addition, a display output indicating that there is any abnormality is displayed on the operation panel 9b with an appropriate figure, character, voice, etc., and the auto cruise lamp is turned off.

  When the auto cruise switch 14c is turned off and the auto cruise is released, the vehicle speed is on the deceleration side, and the left and right brake switches 77a and 77b are both turned on to return the swash plate 34b of the HST 34 to the neutral position. Turning both the left and right brake switches 77a and 77b on means that in the case of a tractor having the left and right brake pedals 16 and 16, the road travels when the left and right brake pedals 16 and 16 are connected, and the field travels when the left and right brake pedals 16 and 16 are not connected. . In traveling in the field, a small turn is possible by stepping on the brake pedal 16 inside the turning direction. Since the left and right brake pedals 16 and 16 have brake switches 77a and 77b, respectively, the fact that both the left and right brake switches 77a and 77b are turned on means that the left and right brake pedals 16 and 16 are connected. It means that the brake is stepped on.

  However, at this time, if the vehicle speed slow response dial 14b is set to a standard value or less, the swash plate 34b of the HST 34 may not return to the neutral position. Therefore, both the left and right brake switches 77a and 77b are turned off (if the foot is released from the brake pedals 16 and 16, the left and right brake pedal switches 77a and 77b are turned off. That is, the brake pedals 16 and 16 are released to release the brakes. Even if the pedals 16 and 16 are stopped, there is an output of the HST 34 and the vehicle starts to run.

  Therefore, when the auto-cruise switch 14c is turned off and the auto-cruise control is released, the increase / decrease direction of the vehicle speed detected by the vehicle speed sensor 53 is on the deceleration side instead of the acceleration side, and both the left and right brake switches 77a, 77b are on. Then, when the vehicle speed slow response dial 14b is set to a standard value or less, the set value of the vehicle speed slow response dial 14b is forcibly returned to the standard value, and the swash plate 34b of the HST 34 is reliably set to the neutral position. return. A flowchart of control in this case is shown in FIG.

  Further, when the forward / reverse lever 10 is made neutral during forward travel, the forward / reverse lever 10 moves from the forward side to the reverse side or from the reverse side when the set value of the vehicle speed slow response dial 14b is slower than the standard value. When operated forward, the vehicle is decelerated and stopped after the operation of operating the forward / reverse lever 10.

  Therefore, in this embodiment, when the forward / reverse lever 10 is reversely operated from the forward side to the reverse side or from the reverse side to the forward side when the set value of the vehicle speed slow response dial 14b is on the side slower than the standard value, When the reverse operation time is shorter than a predetermined value, if the vehicle speed slow response dial 14b is set to the standard value and the vehicle is decelerated, the vehicle is quickly decelerated and stopped in response to the operation of the forward / reverse lever 10. A flowchart of control in this case is shown in FIG.

  In a passenger car, the auto cruise is canceled when the brake pedal 16 is depressed. However, in the tractor, the forward / reverse switching is frequently performed. Therefore, the auto cruise is canceled when the forward / reverse lever 10 is operated from forward to reverse. With this configuration, when the forward / reverse lever 10 is operated to the reverse side, the vehicle is not accelerated to the speed of the auto cruise, and the reverse drive can be performed safely. A flowchart of the control at this time is shown in FIG.

  There are cases where it is desired to accelerate the tractor by depressing the accelerator pedal 15 during auto-cruise traveling. However, conventionally, it has not been determined how to cancel auto-cruising with the amount of operation of the accelerator pedal 15 during auto-cruising. Therefore, there was a problem that the auto cruise switch 14c had to be operated.

  Therefore, during the auto cruise control, the accelerator pedal sensor 15a detects that the operation amount of the accelerator pedal 15 is a predetermined value (for example, 7%) or less, and after that, the accelerator pedal 15 is further depressed to half the predetermined value. When it is detected that the vehicle is depressed more than about (for example, about 12% in total), the auto-cruise is canceled.

  As described above, since the auto-cruise can be canceled by depressing the accelerator pedal 15, it is freed from the trouble of having to release the auto-cruise switch 14c by hand, and the operation of the handle 7 is dedicated to the operation of the work implement. There are advantages you can do. A flowchart of the control at this time is shown in FIG.

  When the engine speed is less than a predetermined value (for example, 500 rpm), the automatic cruise traveling control is canceled. Until now, it was not decided how much to cancel the auto-cruise when the engine speed reached. Therefore, there is a problem that an overload acts on the HST 34 when trying to continue traveling with the engine speed being low.

  Therefore, if the auto cruise is canceled under the above-described conditions, it is possible to prevent an overload from acting on the HST 34, and the auto cruise can be canceled by depressing the accelerator pedal 15, so that the auto cruise switch 14c can be released. There is an advantage that the operation of the handle 7 can be devoted to the operation of the work implement, which is free from the troublesomeness that must be done by hand. A flowchart of the control at this time is shown in FIG.

  Further, when the oil temperature in the hydraulic circuit 34c of the HST 34 is detected and the detected value exceeds a predetermined value (eg, 105 ° C.), the set value of the maximum speed restriction dial 14a is set to a predetermined amount (eg, 10% or 5%). Etc.), the damage of the HST 34 due to the increase in the oil temperature of the HST 34 can be prevented.

  Further, the oil temperature of the hydraulic circuit 34c of the HST 34 is detected, and the detected value is set to a predetermined amount (eg, −5% from the current maximum speed setting value) lower than the current maximum speed setting dial setting value in a plurality of steps. Also good. In the flowchart of this control, deceleration according to the detected oil temperature is possible as shown in FIG. Thus, damage to the HST 34 due to an increase in the oil temperature of the HST 34 can be prevented.

Further, the oil temperature in the hydraulic circuit 34c of the HST 34 is detected, and when the detected value exceeds a predetermined value (eg, 105 ° C.), the maximum speed set value is regulated by a plurality of steps depending on the oil temperature. .
For example, as shown in the flowchart of FIG. 12, when the oil temperature in the hydraulic circuit 34c of the HST 34 is lower than a predetermined value (eg, 105 ° C.), more than 10 minutes have passed since the previous oil temperature control, and the oil temperature control subtraction is further performed. If the number of times is less than 4, it is possible to prevent damage to the HST 34 due to an increase in the oil temperature of the HST 34 by lowering the set value of the current maximum speed restriction dial 14a by a predetermined amount (eg, 5%). In this way, by restricting the maximum speed in a plurality of steps by the oil temperature, it is possible to prevent damage to the HST 34 due to an increase in the oil temperature of the HST 34.

表１に示すように、車速緩慢応答ダイヤル１４ｂの設定値を「遅い」、「標準」及び「速い」と車速緩慢応答ダイヤル１４ｂを回転操作することにより変更できる構成にし、それぞれの回転操作位置でアクセルペダル１５の操作量に対するＨＳＴ３４の応答性を「１ビットの変化時間（ｍｓ）」で変更する。なお、表１に示すように本実施例では、車速緩慢応答ダイヤル１４ｂを回転操作位置が「遅い」方から「速い」方に順次電圧値が高くなるように設定している。
このようにアクセル（ＨＳＴ）ペダル１５の操作量に対する応答性を車速緩慢応答ダイヤル１４ｂにより任意に変更することができる。 The setting value of the vehicle speed slow response dial 14b can be set in a plurality of stages, and the response to the operation amount of the accelerator pedal 15 is made to correspond to the setting value of the plurality of stages of the vehicle speed slow response dial 14b. It can be changed arbitrarily according to the setting value of the response dial 14b.

As shown in Table 1, the setting value of the vehicle speed slow response dial 14b can be changed to “slow”, “standard” and “fast” by rotating the vehicle speed slow response dial 14b, and at each rotational operation position, The response of the HST 34 to the operation amount of the accelerator pedal 15 is changed by “1 bit change time (ms)”. As shown in Table 1, in this embodiment, the vehicle speed slow response dial 14b is set so that the voltage value sequentially increases from the “slow” to “fast” rotational operation position.
Thus, the response to the operation amount of the accelerator (HST) pedal 15 can be arbitrarily changed by the vehicle speed slow response dial 14b.

If the 1-bit change time (ms) according to the set value of the vehicle speed slow response dial 14b is regulated from the operation amount of the accelerator pedal 15 0%, the accelerator speed is set to the slow side and the fast side when the vehicle speed slow response dial 14b is set. There has been a case where a problem occurs in which the operation amount of the pedal 15 changes.
In such a case, up to a predetermined value (10%) of the operation amount of the accelerator (HST) pedal 15, the operation output on the acceleration side of the HST 34 with respect to the operation amount of the accelerator pedal 15 is performed, and the operation amount of the accelerator pedal 15 is When the predetermined value (10%) is exceeded, according to the set value of the vehicle speed slow response dial 14b, for example, by running according to the change time (ms) of 1 bit shown in Table 1, The problem can be improved.

When the vehicle speed is decelerated by removing the foot from the accelerator pedal 15, the control by the vehicle speed slow response dial 14b is stopped at a predetermined value (for example, 110%) or less of the operation amount of the accelerator pedal 15 as in the case of the acceleration. If the vehicle is decelerated rapidly with the standard value, a shock will occur when the vehicle stops.
Therefore, when the vehicle speed is decelerated by removing the foot from the accelerator pedal 15, even if the control by the vehicle speed slow response dial 14b is continued even if the operation amount of the accelerator pedal 15 is less than a predetermined value (for example, 10%), the vehicle speed is slowly decelerated. There is no sudden stop and no shock occurs.

When the depression of the accelerator pedal 15 is stopped and the foot is released from the accelerator pedal 15 (when the speed is decelerated), if the difference between the current travel speed and the target travel speed on the deceleration side is greater than a predetermined value , Deceleration output is performed with the amount of change twice the amount of change on the acceleration side.
This is because if the difference between the maximum speed value and the target deceleration value is too large when decelerating from the maximum speed at which the operation amount of the accelerator pedal 15 is at the maximum value to the target low speed, the driving feeling is poor at the time of deceleration. This is to solve this problem.

Further, when the operation of depressing the accelerator pedal 15 is stopped and the foot is released from the accelerator pedal 15 (when the speed is reduced), the difference between the current traveling speed and the target traveling speed on the deceleration side is not more than a predetermined value. When the deceleration output is performed with a change amount twice as large as the acceleration side change amount, a shock is generated just before the vehicle stops.
In order to prevent this, if the difference between the current traveling speed and the target deceleration-side traveling speed is equal to or less than the predetermined value, the vehicle is stopped by performing deceleration output with the same amount of change as the acceleration-side variation. There is no immediate shock.

When the accelerator pedal 15 is operated to the deceleration side, the wheels are mechanically locked when both the left and right brakes are activated. However, the set value of the solenoid valve of the trunnion hydraulic proportional valve 65 of the HST 34 when the accelerator pedal 15 is activated is the vehicle speed slow response dial 14b. Due to the influence of the set value, there was a problem of continuing running even when the brakes were turned off.
Therefore, in order to prevent this phenomenon, when both the left and right brake switches 77a and 77b are on during deceleration, and the set value of the vehicle speed slow response dial 14b is below the standard value, the vehicle speed slow response dial 14b is used. By decelerating with the set standard value, the vehicle can be quickly stopped. A flowchart of this control is shown in FIG.

  When the vehicle speed slow response dial 14b is set to a standard value or less, it takes time to reach the target speed even if the accelerator pedal 15 is operated (control to move the trunnion shaft 30 of the HST 34 slowly). . At this time, when the auto cruise is canceled and the vehicle is on the deceleration side, the vehicle is slowly decelerated because of the setting. Canceling auto-cruise basically wants to decelerate early, so only for such deceleration, even if the vehicle speed slow response dial 14b is set below the standard value, the trunnion shaft 30 of the HST 34 is made faster (standard (By value) to move and decelerate quickly. In such a case, when the input of the HST pedal sensor 15a, that is, when the accelerator pedal 15 is depressed and accelerates, the vehicle speed slow response dial 14b is originally set to a standard value or less, so it accelerates slowly. Control to try.

  Of course, when the power is turned off, even if the vehicle speed slow response dial 14b as described above is set to a standard value or less, the control for quickly decelerating by moving the trunnion shaft 30 of the HST 34 (by the standard value) is cancelled. A flowchart of this control is shown in FIG.

  When the traveling vehicle is outputting forward or reverse, there is an abnormality in the sensor 15a of the accelerator pedal 15, and when the sensor value is out of the specified range, the traveling is stopped after a predetermined change time has elapsed, so that the vehicle is not stopped suddenly. It is possible to stop safely while preventing the occurrence of shock. A flowchart of this control is shown in FIG.

  If there is an abnormality in the sensor 15a of the accelerator pedal 15 while the traveling vehicle is moving forward or backward, and the sensor value is out of the specified range, the traveling is stopped after a predetermined change time has elapsed, and once the abnormality processing mode is entered. Even if the accelerator pedal sensor 15a returns to normal or even if the accelerator pedal 15 is depressed, safety is achieved by continuing the vehicle stop process.

DESCRIPTION OF SYMBOLS 1 Traveling vehicle body 2 Front wheel 3 Rear wheel 5 Engine 5a Engine rotation sensor 6 Handle post 7 Steering handle 8 Fuel tank 9 Pilot seat (seat) 9b Operation panel 10 Forward / reverse lever 10a Forward solenoid 10b Reverse solenoid 10c Forward / reverse lever position sensor DESCRIPTION OF SYMBOLS 11 Throttle lever 11a Throttle lever sensor 12a, 12b Lever guide 13 Step floor 14a Maximum speed control dial 14b Vehicle speed slowness response dial 14c Auto cruise switch 14ca Auto cruise speed increase switch 14cb Auto cruise deceleration switch 15 Accelerator pedal 15a Accelerator pedal position sensor 16 Brake pedal 21 Sub transmission lever 21a Sub transmission lever position sensor 22 Bonnet 23a Mid PTO transmission lever 23b Rear PTO transmission lever -24 4WD lever 30 trunnion shaft 30a trunnion shaft angle sensor 31 link 34 hydrostatic continuously variable transmission (HST) 34a hydraulic pump 34b hydraulic motor 34c hydraulic closed circuit 34d swash plate 35 travel output shaft 35a HST output shaft rotation sensor 36 rotation Shaft 38 Intermeshing transmission 39 Sub-transmission clutch 43 Transmission shaft 46 Differential device 47, 57, 58, 59 Gear 48 Front wheel output shaft (4WD shaft)
51 pump output shaft 52 PTO shaft 53 rotational speed sensor (vehicle speed sensor) 54 hydraulic clutch 55 rear PTO shaft 56 mid PTO shaft 63 switching valve 65 trunnion hydraulic proportional valve 77a left brake switch 77b left brake switch 100 controller

Claims (4)

An engine (5),
Engine speed detecting means (5a) for detecting the speed of the engine (5);
A trunnion shaft (30) and a swash plate having a swash plate (34d) capable of changing the inclination angle provided in the hydraulic pump (34a) by inputting the power of the engine (5) and operating the hydraulic pump (34a). (34d) is supplied with hydraulic oil from the closed hydraulic circuit (34c) to the hydraulic motor (34b), and the hydraulic motor (34b) drives the travel output shaft (36) to the hydrostatic transmission ( 34)
A gear meshing-type sub-transmission (38) operated by the output of the hydraulic continuously variable transmission (34);
Traveling wheels (2, 3) driven by the output of the auxiliary transmission (38);
A forward / reverse lever (10) for switching the forward or reverse rotation of the traveling wheel (2, 3) according to the forward or reverse rotation angle of the trunnion shaft (30);
A forward / reverse lever position sensor (10a) for detecting an operation position of the forward / reverse lever (10);
An accelerator pedal (15) that changes the output amount of the HST 34 by changing the rotation angle of the trunnion shaft (30) in accordance with the depression amount;
An accelerator pedal detection means (15a) provided at the base of the accelerator pedal (15) for detecting the depression amount of the accelerator pedal (15);
The inclination angle of the forward or reverse direction of the swash plate (34d) fixed to the trunnion shaft (30) of the hydraulic continuously variable transmission (34) is adjusted according to the detected value of the accelerator pedal sensor (15a). A trunnion hydraulic proportional valve (65) for adjusting the hydraulic output of the hydraulic continuously variable transmission (34), and a sub-shift operation means (21) for operating the sub-shift by the sub-transmission device (38) to the low speed side and the high speed side. )When,
An operation means for auto cruise traveling (auto cruise switch) (14c) for keeping the traveling speed of the traveling wheels (2, 3) constant;
When the forward / reverse lever position sensor (10a) detects that the forward / reverse lever (10) is on the reverse side, it has a control structure for canceling the automatic cruise travel even if the operation means (14c) for the automatic cruise travel is operating. A traveling vehicle provided with a control device (100). An accelerator pedal detecting means (15a) for detecting the depression amount of the accelerator pedal (15), and an accelerator pedal detecting means (15a) that the operation amount of the accelerator pedal (15) is not more than a predetermined value during the automatic cruise traveling control. When the accelerator pedal (15) is further depressed and the accelerator pedal detection means (15a) is detected to be equal to or greater than a predetermined value, the control device (100) is configured to cancel the automatic cruise traveling. The traveling vehicle according to claim 1, wherein the traveling vehicle is provided.   The travel according to claim 1, wherein the control device (100) is provided with a control structure for canceling the auto-cruise travel control when the engine speed detecting means (5a) detects that the engine speed is less than a predetermined value. vehicle. Vehicle speed detection means (53) for detecting the rotational speed of the traveling wheels (2, 3);
Brake switches (77a, 77b) for detecting depression of each of the brake pedals (16, 16);
A vehicle speed slow response dial (14b) for setting the rotation angle of the trunnion shaft (30) of the hydraulic continuously variable transmission (34) to a vehicle speed slow response speed;
When the auto-cruise traveling operation means (14c) is turned off and the auto-cruise is released, the vehicle speed detecting means (53) detects that the vehicle speed is on the deceleration side, and the brake switches (77a, 77b) are on. If the vehicle speed slow response dial (14b) is set to a standard value or less, the control configuration for forcibly returning the set value of the vehicle speed slow response dial 14b to the standard value or the vehicle speed slow response dial (14b) The forward / reverse lever sensor (10c) detects that the forward / reverse lever (10) is reversely operated from the forward side to the reverse side, or from the reverse side to the forward side, and When the reverse operation time between the forward side and the reverse side is shorter than a predetermined value, the control device is configured to decelerate by setting the set value of the vehicle speed slow response dial (14b) as a standard value. 100). The traveling vehicle according to claim 1, wherein the traveling vehicle is provided at 100).

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