JPH11264465A - Control structure for continuously variable transmission type working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a practical vehicle speed from getting different from a supposed speed by controlling an output shaft by a shift position correcting means, when an error is generated between a set shift output rotation speed and a detecting shift output rotation speed in setting the advancement. SOLUTION: A movable swash plate of a hydraulic pump moves to a set position by a lever operation of a continuously variable transmission 3 and the lever set position is detected by a lever angle sensor S3. When a set value is set in a rotation speed setting device 23 in response to the detected value and the setting of the advancing area of the movable swash plate position is confirmed, a controller C reads the set value by the set device 23 based on the detected value. It confirms that it is within a work rating rotation speed or less and reads the value detected by a rotation speed sensor S2. An error allowable quantity is calculated based on the rotation speed set value, and when the rotation speed detection value is higher than the upper limit value of the error allowable range of the rotation speed set value, the movable swash plate is moved to the low speed side by a swash plate control motor 8 so as to reduce the vehicle speed. The vehicle speed is increased in the reversed case. The practical vehicle speed is thus matched to the supposed shift position rightly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a continuously variable transmission (H).
The present invention relates to a control structure for correcting a shift position of a continuously variable transmission and a control structure automatically corresponding to a type of a working machine to be mounted in a work vehicle such as an agricultural work vehicle (agricultural tractor) shifted in ST).

[0002]

2. Description of the Related Art Conventionally, in a ground work vehicle such as an agricultural work vehicle (agricultural tractor) equipped with an HST, an electronic work pitch (for example, a tillage pitch, a seeding pitch, a transplantation pitch, etc.) is required to be uniform. 2. Description of the Related Art A configuration in which a vehicle travels while controlling a work load and a work traveling speed using a governor device or the like is known.

In performing such control, agricultural tractors and the like change the model and size of the working machine to be mounted in accordance with the type of work to be performed. Since the work load, the work traveling speed, the height of the work machine, and the like differ depending on the type of the work machine mounted, the worker sets an appropriate value every time the work machine is replaced.

[0004]

In the above technology,
Even though the work load and the work traveling speed can be made uniform by the electronic governor control, nothing is done unless the set load or traveling speed is an appropriate value. The problem here is that H
In ST, a fixed output shaft rotation speed is not always obtained with respect to a certain shift position, that is, the position of the movable swash plate of the hydraulic pump, and the speed fluctuates due to a change in conditions such as load and oil temperature. This is a problem. The position of the movable swash plate is set using the HST operation lever (main shift lever). If the actual vehicle speed is different from the vehicle speed assumed by the operator, the lever operation is performed while looking at the display of a speedometer or the like. Returning the vehicle speed to a normal value by performing the above operation is burdensome for the operator. The electronic governor device controls the output shaft and the load of the engine based on the detection of the load, and cannot correct the error of the vehicle speed caused by the error of the rotation speed of the output shaft of the HST.

Therefore, it is conceivable to provide a means for detecting such an error by an electric motor or the like and automatically correcting the movable swash plate position of the HST hydraulic pump in addition to the HST operation lever. The problem is that the work load fluctuates in accordance with the vehicle speed correction control. For example, in an overload state, the HST output shaft is required to increase the vehicle speed just because the actual vehicle speed is lower than the set vehicle speed. When the speed increase control is performed, the torque of the output shaft is reduced, so that the degree of overload is further increased, and there is a risk of engine stall.

Further, if it is necessary to artificially set a load, an elevating device, a vehicle speed, and the like in accordance with a work machine to be mounted on an agricultural tractor or the like as in the above-mentioned conventional technology, the setting operation is complicated. It is difficult to memorize each setting value, and if possible, if the control corresponding to it is set automatically only when frequently used work equipment is installed,
The burden on the operator is greatly reduced.

[0007]

SUMMARY OF THE INVENTION The present invention provides the following control structure in order to solve the above-mentioned problems in a continuously variable work vehicle. First, at least a continuously variable transmission and a control mechanism thereof are provided, and the control mechanism of the continuously variable transmission includes at least a shift position setting unit, a shift position detection unit, a shift position correction unit, A continuously variable transmission operation comprising: a transmission output rotation number setting means for setting the rotation number of the output shaft of the continuously variable transmission according to the set value of the transmission position setting means; and a transmission output rotation number detecting means. In the vehicle, when an error occurs between the set shift output rotational speed and the detected shift output rotational speed at the time of forward setting, in order to correct this, the shift position correcting means is used to adjust the speed of the continuously variable transmission. It is configured to perform output shaft control.

Secondly, in the control mechanism of the continuously variable transmission work vehicle having the above-mentioned structure, when the detected shift output rotational speed is lower than the set shift output rotational speed by a certain value or more, whether the detected engine load is larger than the set engine load, Alternatively, when the detected engine speed is within a range in which engine stall may occur when viewed from the set engine speed, the output shaft control of the continuously variable transmission by the shift position correcting means is not performed.

Third, the internal combustion engine and its control mechanism, the continuously variable transmission and its control mechanism are provided at least, and the control mechanism of the internal combustion engine includes at least an engine speed detecting means, an engine speed, Setting means, an engine load detecting means, and an engine load setting means, wherein the control mechanism of the continuously variable transmission includes at least a shift position setting means, a shift position detecting means, a shift position correcting means, A shift output rotational speed setting means for setting the rotational speed of the output shaft of the continuously variable transmission in accordance with the set value of the shift position setting means; and a shift output rotational speed detecting means. If an error occurs between the shift output speed and the detected shift output speed,
In order to correct this, in the control structure of the continuously variable transmission type work vehicle, wherein the output shaft control of the continuously variable transmission is performed by using the transmission position correction means, the transmission output rotational speed setting means includes The set value is changed in accordance with a set speed stage of the subtransmission that can be set to a plurality of stages arranged in series with the speed transmission.

Fourthly, the hydraulic continuously variable transmission includes at least a hydraulic stepless transmission and a control mechanism therefor, and a power take-out shaft for a working machine, and the control mechanism of the hydraulic stepless transmission has at least a shift position setting means. Speed change speed detection means; speed change position correction means; speed change output speed setting means for setting the speed of the output shaft of the continuously variable transmission in accordance with the set value of the speed change position setting means; Number detection means, comprising a hydraulic pressure detection means for forward drive and a hydraulic pressure detection means for reverse of the hydraulic circuit,
The continuously variable transmission work vehicle, wherein the power take-out shaft for the working machine includes at least a power take-out shaft drive detection unit that detects whether the work machine power drive shaft is in a driving state or a non-driving state. When one or more of the shift position detecting unit, the shift output rotational speed setting unit, the shift output rotational speed detecting unit, and the forward drive hydraulic pressure detecting unit determine that the work vehicle is in the forward state. Further, when the reverse drive hydraulic pressure detecting means detects that the vehicle is in the reverse state, it is determined that the operation state is the work state of the specific work machine, and the control corresponding thereto is performed.

[0011]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall side view of a farming tractor as an embodiment of a work vehicle according to the present invention, and FIG. 2 is a side view of a portion centering on a clutch housing and a transmission case in the farming tractor shown in FIG. 3 is
FIG. 4 is a block diagram of the HST control system according to the present invention, FIG. 5 is a basic flowchart of the HST output correction control according to the present invention, and FIG. 6 is a control flowchart of FIG. FIG. 7 is a flowchart showing an HST output correction control in which control for correcting the HST rotation speed set value is added to the control flow shown in FIG. FIG. 8 is a flowchart of the added HST output correction control, and FIG.
FIG. 9 is a HST output correction control flowchart to which control for increasing the speed of the ST output shaft is added, FIG. 9 is a control flowchart for automatically detecting the installation of the rotary tiller and performing the rotary tillage control, and FIG. FIG. 11 is a control flowchart for automatically detecting the installation of the rotary cultivator and controlling the vehicle speed for the rotary tilling. FIG. 11 is a flowchart following the flowchart of FIG. FIG. 7 is a flowchart of a vehicle speed control routine for changing a set value regarding the vehicle speed.

The overall configuration of a continuously variable agricultural traveling vehicle (tractor) according to the present invention will be described with reference to FIG. Left and right front wheels 19 and right and left rear wheels 20 are suspended in front and back of the vehicle body, and an engine (internal combustion engine) E is mounted in a front hood 18. An electronic governor device (internal combustion engine drive control device)
2 is attached. Power from engine E is rear wheel 20
A clutch housing 4 and a transmission case 5 are connected to each other at the lower part of the vehicle in the front-rear direction so as to be transmitted to the lower part of the vehicle. A possible auxiliary transmission (not shown) is provided, an HST 3 is provided between the clutch housing 4 and the transmission case 5, and a PTO transmission mechanism (not shown) is provided in the rear half of the transmission case 5. That is, the engine power is transmitted to the axle of the rear wheel 20 through the main clutch mechanism, the auxiliary transmission, the main clutch mechanism, and the HST3 as a traveling drive system, while the main clutch mechanism is transmitted as the PTO drive system. The power is transmitted to the PTO shaft 7 via the mechanism and the PTO transmission mechanism.
The power can be transmitted to the front wheels 19 from the traveling drive system.

A step 11 is formed on the clutch housing 4 and a front portion of the step 11 and the bonnet 18 are provided.
A dashboard 12 is erected at the rear of the vehicle, a steering column 13 is disposed in the dashboard 12 in a front-rear inclination, an upper end of the steering column 13 projects rearward and upward, and a steering handle 14 is disposed at the upper end. ing. A rear portion of the step 11 is surrounded on both left and right sides by fenders 15, and a seat 16 is disposed between the fenders 15. Lever guide 1 for various levers such as HST operation lever (main shift lever) 9 using the upper surfaces of left and right fenders 15
a and a switch panel 1b on which various switches are arranged. A sub-transmission lever 10 that is a setting means of the sub-transmission that can be set to a plurality of speeds is provided inside these. The grip portion of the HST operation lever 9 is provided with a one-touch elevating switch SW1 that can be set up and down. An arrangement portion of these levers and switches is referred to as an operation unit 1. The upper part of the part from the front dashboard 12 to the rear seat 16 and the operation unit 1 is covered with a cabin 17.

Furthermore, on the upper part of the transmission case 5,
A (hydraulic) ground work machine elevating control device 6 is disposed. The ground work machine elevating control device 6 has left and right lift arms 6a, 6a protruding rearward, and is turned up and down. Also, a PTO shaft 7 for driving a ground work machine is protruded from the rear end of the transmission case 5, and the PTO shaft 7 for mounting a ground work machine (not shown) that rotates vertically with the vertical movement of the lift arm 6 a. The link mechanism is protruded rearward, and a ground work machine (such as a rotary cultivator) is mounted on the rear of the vehicle at the rear end of the link mechanism so that the link mechanism can be moved up and down, and is driven via a PTO shaft (power take-out shaft) 7. And

The vehicle according to this embodiment is a continuously variable transmission type, that is,
The traveling direction and speed are controlled by a hydraulic continuously variable transmission (HST). Arrangement structure of the HST3, an HST operating lever 9 as a shift position setting means for setting a movable swash plate position of the hydraulic pump of the HST3, and a swash plate control motor 8 as a shift position correction means in the HST control device. 1 to 3 will be described. First, HS
T3 is provided in the rear half of the clutch housing 4 and the front half of the transmission case 5. The HST 3 connects a front horizontal hydraulic pump P and a rear horizontal hydraulic motor M via a vertical plate-shaped center section 3c to fluidly communicate with each other, and the center section 3c is connected to the clutch housing 4 and the transmission. It is interposed between the case 5 and connects the two. HS ahead of hydraulic pump P
The T input shaft (pump shaft) 3a and the HST output shaft (motor shaft) 3b are provided horizontally behind the hydraulic motor M, respectively. A transmission mechanism (not shown) is provided in a rear half portion of the transmission case 5, and is provided with an HS.
The rotation of the T output shaft 3b is shifted and transmitted to the axle of the rear wheel 20.

The front half of the clutch housing 4 is a main clutch, which forms a clutch mechanism connected to the output shaft of the engine E, and also has an upper opening 4 as shown in FIG.
The lower end portion of the steering column 13 is fitted from a to form a steering mechanism. A swash plate control motor (electric motor) 8 for controlling the position of the movable swash plate of the hydraulic pump P is provided above a boundary between the first half and the second half of the HST hydraulic pump P. It is covered by the dashboard 12 behind it.

At the output of the swash plate control motor 8, there is provided a motor arm 8b rotatable in a fixed area, and the motor arm 8b and the motor arm 8b are disposed immediately before the HST hydraulic pump P. A link mechanism is connected between the vertical rotating shaft 21 shown in FIG. 2 and FIG. 3, and a link mechanism is further connected between the rotating shaft 21 and the trunnion shaft of the HST hydraulic pump P. In this way, the rotating shaft 21 rotates in accordance with the driving of the movable swash plate motor 8, and the movable swash plate of the hydraulic pump P rotates accordingly, thereby changing the shift position.

The HST operating lever 9 is a shift position setting means for artificially setting the movable swash plate of the hydraulic pump P.
Is disposed on a lever guide 1a formed on one fender 15 in the operation unit 1, and the connecting rod 22 shown in FIG.
Is connected to an arm 21a fixed to the arm. That is, H
The connecting rod 22 is pushed and pulled by the rotating operation of the ST operating lever 9, thereby rotating the rotating shaft 21, and the hydraulic pressure is changed in the same manner as when the rotating shaft 21 is rotated by the swash plate control motor 8. The movable swash plate of the pump P is moved.

The agricultural tractor shown in FIGS. 1 to 3 is an embodiment to which a load control mechanism using the HST of the present invention and its control device is applied. The system configuration related to this load control mechanism is shown in FIG. A more detailed description will be given.

Various input means such as sensors and switches for the controller C for HST control are provided in the operation unit 1, governor 2, and HST3. First, these input means will be described. In HST3, the swash plate angle sensors S1 and HS that detect the angle (shift position) of the movable swash plate of the hydraulic pump P (that is, are shift position detecting means).
The rotation speed of the T output shaft (motor shaft) 3b is detected (that is,
HST rotation speed sensor S which is a shift output rotation speed detection means)
2. It has a forward pressure sensor (forward pressure detecting means) S3 and a reverse pressure sensor (reverse pressure detecting means) S4 for detecting the operating oil pressure in the hydraulic circuit in which the operating oil flows during forward driving. The detection voltage (A / D) is input from the swash plate angle sensor S1 and the pressure sensors S3 and S4 to the controller C, and the detected rectangular wave signal is input from the HST rotation speed sensor S2.

The HST output shaft 3b is proportional to the lever position (lever angle) of the HST operation lever 9 described later.
An HST rotation speed setting device (shift output rotation speed setting means) 23 for setting the rotation speed is provided to receive the output signal from the controller C and perform the setting. Is input to the controller C.

In the operation section 1, an HST operation lever (main means for setting an HST shift position (means for setting a traveling direction, a shift position or a shift amount)) connected to the movable swash plate by a mechanical link mechanism. HST lever angle sensor S5 for detecting the rotation angle of the
Is provided. As described above, the ascending input signal and the descending input signal are input to the controller C from the one-touch elevating switch SW1 disposed on the grip portion of the HST operation lever 9.

Further, in the operation unit 1, in addition to the sub-transmission switch SW2 for inputting an input signal corresponding to each set number of steps of the sub-transmission lever 10 to the controller C, a PTO transmission switch SW3, an automatic / manual mode switching switch SW
4. ON / OF by ON / OFF operation of PTO clutch
Various switches SW such as a PTO clutch switch SW5 (power take-off shaft drive detecting means)... Are provided, and an input signal corresponding to each switch is input to the controller C in accordance with each switch switching.

The electronic governor device (internal combustion engine drive control device) 2 for adjusting the fuel injection amount of the engine E has a load factor monitor (that is, a load factor monitor for detecting an engine load factor (engine speed / set speed)). An engine load detecting means) M1 and a rotational speed monitor (that is, engine rotational speed detecting means) M2 are provided, and each monitor rectangular wave is input to the controller C. A load factor setting device 24 is provided as an engine load setting device, and a signal (voltage) based on the set value of the set load factor is input to the controller C. Further, an engine speed setting means such as an accelerator lever and an accelerator pedal is provided, and the detected voltage is input to the electronic governor device 2 and the controller C from an accelerator sensor S6 for detecting the set amount.

As the output means, an actuator (hydraulic cylinder or the like) 6b for elevating and lowering the lift arm 6a in the work machine elevating and lowering control device 6 is provided, and an output for elevating and lowering is outputted from the controller C to the actuator 6b. . Further, a display panel 25 having various display lamps L such as an overload display lamp L1 and an automatic / manual mode display lamp L2... Is provided, and the controller C outputs ON / OFF to each display lamp L. Is made. In this case, when the detected load factor of the load factor monitor M1 is higher than the load factor set by the load factor setting device 24 as described later, the controller C determines that the controller C is in the overload state. Thus, an ON output for lighting is performed. Also, the battery checker 26 and the controller C
Are mutually communicated with.

In the HST 3, the rotation speed and the rotation direction of the output shaft 3b, which is the motor shaft of the hydraulic motor M, are changed by the displacement of the movable swash plate of the hydraulic pump P. The movable swash plate moves following the manual operation of the HST operation lever 9 by the operator, while the swash plate control is an electric (D / C) motor provided as a shift position correcting means for load control according to the present invention. It can be moved by driving the motor 8. The swash plate control motor 8 is provided with a motor drive unit 8a, and the controller C outputs a forward rotation output signal SG1, a reverse rotation output signal SG2, and a drive stop output signal SG3 to the motor drive unit 8a. Forward rotation output signal SG
1 and a reverse rotation output signal SG2 are ON / OFF output signals, which are alternately output, and one of SG1 and SG2 is output, and at the same time, a drive stop output signal which is a PWM (pulse wave signal). SG3 is output, and the drive speed is set according to the duty value of the pulse wave. On the basis of these output signals SG1, SG2, SG3, the motor drive unit 8a sends a drive signal SG5 to the swash plate control motor 8.
Is transmitted, and the swash plate control motor 8 is driven at a predetermined speed to the normal rotation side or the reverse rotation side to move the movable swash plate.

Thus, for example, the normal rotation output signal SG1
And the drive stop output signal SG3 are output simultaneously,
The movable swash plate moves to the side on which the swash plate control motor 8 rotates forward (the forward side) at a speed based on the pulse wave of the drive stop output signal SG3. If the reverse rotation output signal SG2 and the drive stop output signal SG3 are output at the same time, the movable swash plate moves to the reverse side at a predetermined speed.

The motor drive unit 8a is provided with an overload detection sensor. If an overload of the swash plate control motor 8 is detected, this detection signal (overload abnormality signal) S
G4 is input to the controller C, and based on this, a drive stop output signal SG3 is transmitted with a duty value of 0, and the swash plate control motor 8 is immediately stopped.

On the other hand, the movable swash plate is provided with limiters in the forward and backward movement ranges. Correspondingly, the swash plate control motor 8 is also provided with a forward limit and a reverse limit. When the swash plate control motor 8 reaches each limiter, the forward rotation limit signal SG6 or the reverse rotation limit signal SG7 is transmitted to the controller C.

In the above-described configuration of the agricultural work vehicle (agricultural tractor) and the system configuration of the HST control mechanism, the control by the load control mechanism according to the present invention will be described with reference to the flowcharts shown in FIGS.

First, FIG. 5 is a basic flowchart relating to the HST output correction control structure among the control structures according to the present invention. By operating the HST operation lever 9, the movable swash plate of the hydraulic pump P moves to the set position in the HST3, and the set position of the HST operation lever 9 at this time is detected by the lever angle sensor S3. Further, a set value is set in the HST rotation speed setter 23 in accordance with the detection value of the lever angle sensor S3. (For example, the H
The set value HR in the ST rotation speed setter 23 is a proportional value of the detection value LS of the lever angle sensor S3. That is, HR
= K x LS, K is a proportional constant. )

Based on the value detected by the lever angle sensor S3,
When it is confirmed that the movable swash plate position is set in the forward range (St1), the controller C reads the HST rotation speed set value HR by the HST rotation speed setting device 23 based on the detected value (St2). . Then, first, it is checked whether it is equal to or lower than the rated working speed (in this embodiment, this is set to 2800 rpm), and if this is checked (St3), the HST speed by the HST speed sensor S2 is further determined. Read the detection value KR (St
4). It should be noted that HR (> 0) and K
R indicates a higher value as the movable swash plate is on the higher speed side.

Here, the controller C calculates an allowable error amount ▲ HR (> 0) based on the read HST rotation speed set value HR, and the HST rotation speed detection value KR is used as the HST rotation speed. A comparison operation is performed to determine whether or not the error is within an error allowable range based on the numerical set value HR. As a result of this comparison operation, the HST rotation speed detection value KR is equal to the upper limit value of the allowable error range of the HST rotation speed setting value HR (HR + ▲ HR).
If (KR> HR + ▲ HR) is higher than (St5),
Since the actual HST rotation speed is much higher than the set HST rotation speed and the vehicle speed is higher than the set vehicle speed, the swash plate control motor 8 is used to lower the movable swash plate of the HST hydraulic pump P at a low speed. Side (St6), HS
The T output shaft 3b is decelerated, and the vehicle speed is reduced so as to approach the set vehicle speed.

On the other hand, the HST rotation speed detection value KR is equal to the lower limit value (HR-−H) of the allowable error range of the HST rotation speed setting value HR.
R) (KR <HR−−HR) is lower than (St)
7) Since the actual HST rotation speed is much lower than the set HST rotation speed, and the vehicle speed is lower than the set vehicle speed, the HST rotation is performed using the swash plate control motor 8.
The movable swash plate of the hydraulic pump P is moved to the high speed side (St
8) The speed of the HST output shaft 3b is increased to increase the vehicle speed so as to approach the set vehicle speed.

By such vehicle speed correction control, the vehicle speed is maintained at substantially the set speed, and for example, in the ground work such as the seeding work, an accurate work pitch (seeding pitch) corresponding to the set speed can be obtained. In addition, in combination with governor control or the like, constant speed traveling is also possible, and a uniform seeding pitch can be obtained.

As described above, the HST rotation speed setting device 2
3 corresponds to the lever position (detection value LS of the lever angle sensor S5) set by the HST operation lever (main transmission lever) 9 (for example, HR = K as described above).
XLS), but if the sub-transmission that can be set in a plurality of stages is on the upper side of the HST, the set value HR is changed in accordance with the setting of the sub-transmission. For example, in the case of a subtransmission having a first gear and a second gear, H
R = K ₁ × LS, and HR = K ₂ × LS in the case of the second speed. (K ₁ is a proportionality constant that auxiliary speed change device corresponds to the case one speed, K ₂ is a constant of proportionality also corresponding to the case of a two-speed.)

The flowchart shown in FIG. 6 is obtained by adding a correction of the HST rotation speed set value HR to the number of sub-gear stages in the flowchart shown in FIG. That is, the HST rotational speed detection value HR by the HST rotational speed setting unit 23 is read (St2), and the sub-shift stage number is read by the setting of the sub-transmission switch SW2 in the operation unit 1 (St2 + a), and the HST rotational speed set value is set. The HR is corrected in accordance with the read sub-gear number (St2 + b), and then the HST rotation speed detection value KR is read as described above, and the same control as that shown in FIG. 5 is performed (St3 to S).
t8).

Further, as described above, the operating section 1 has a PTO speed change switch SW3 capable of setting a plurality of speed stages of the PTO shaft.
Are arranged. Assuming that the engine speed is constant, the vehicle speed is set by the HST operation lever 9 (the detection value LS of the lever angle sensor S5) and the setting of the sub-transmission lever 10 (input value of the sub-transmission switch SW2). The working efficiency, that is, the working pitch (tiling pitch, etc.) is determined by the combination of the vehicle speed and the driving speed of the working machine (for example, in the case of a rotary cultivator, the rotation speed of a rotary tilling claw). . Therefore, in setting the working pitch, for example, as shown in Table 1, the set number of sub-transmissions and PT
The above HST is determined by a combination of the number of shift speeds of the O transmission (in this embodiment, the first speed and the second speed can be set, respectively).
The set value of the rotation speed set value HR is made to correspond.

[0039]

[Table 1]

In the flowchart shown in FIG. 7, the table of Table 1 is stored in the controller C, and the step (St2 + a) of reading the number of sub-gears in the flowchart shown in FIG. The reading step (St2 + a ')
The step (St2 + b) of correcting the HST rotation speed set value HR with the number of sub-gear stages is the step (St2 + b ') of correcting the HST rotation speed set value HR based on the table of Table 1.

In the basic control of the HST output correction shown in FIGS. 5 to 7 described above, in the deceleration control of the HST output shaft 3b in the case of (KR> HR + ▲ HR), the torque of the output shaft 3b increases. So there is no problem, but on the other hand, (KR <
In the case of HR- ▲ HR), the speed increase control of the HST output shaft 3b reduces the torque of the output shaft 3b, so that there is a possibility that the HST output shaft 3b becomes overloaded or stalls.

The flowchart shown in FIG. 8 is the same as the basic flowchart shown in FIG. 5, except that when (KR <HR− ▲ HR), the overload state is detected by using the detecting means of the electronic governor device 2. If the engine speed is low enough to cause engine stall, control is performed to avoid speed-up control. This flowchart is also applicable to the flowcharts shown in FIGS. In this case, in the flowchart shown in FIG. 8, the steps (St2 + a, St2 + b) shown in FIG.
Alternatively, the steps (St2 + a ', St2 +
b ′) may be inserted after the step (St2).

As described above, in the HST output correction control flow, the HST rotational speed detection value KR by the controller C
As a result of performing a comparison operation with the HST rotation speed set value HR, if KR <HR− ▲ HR (St7), the detected load factor EL by the load factor monitor M1 is read (S7).
t10) Compared with the set load factor SL preset by the load factor setter 24, the detected load factor EL is equal to the set load factor S.
If not more than L (St11), the set engine speed ES is read by an accelerator sensor (engine speed setter) S6 (St12), and the detected engine speed ER is detected by an engine speed monitor (sensor) M2. Is read (St1
3). In the overload state, the overload indicator lamp L1 is lit. Here, the controller C sets the allowable engine speed reduction amount DR in advance (or calculates the allowable engine speed reduction amount DR based on the read set engine speed ES by using a certain arithmetic expression. It is confirmed that the detected engine speed ER is within the allowable reduction range (ER ≧ ES-DR) with respect to the set engine speed ES (St14), and the speed of the movable swash plate is increased for the first time. Side, that is, speed-up control of the HST output shaft 3b (St15).

As a result of reading the engine load factor EL, if it is determined that the engine is in an overload state (EL> SL) (St16), and even if the engine is in a low load state,
When the detected engine speed ER is smaller than an allowable lower limit (ES-DR) for the set engine speed ES (ER <ES-
DR) (St17), the speed increase control of the HST output shaft 3b accompanied by the torque reduction is not performed, and the engine stall can be avoided. As a result, the vehicle speed becomes lower than the set speed and the work pitch becomes shorter than the set pitch. This may be corrected by controlling the engine speed by governor control.

The control shown in FIGS. 5 to 8 is based on the HST
9 relates to the vehicle speed correction control in FIG.
A flowchart relating to determination of a mounting work machine (rotary tiller) using the HST shown in FIG. 10 will be described.

In the agricultural tractor, in the control of the engine speed and load by governor control, the output control of the HST, the control of the height of the working machine, etc., unless the control corresponding to the working machine to be mounted is performed, respectively, It is not possible to do good work for the machine. That is, various setting values such as the engine load factor must be changed according to the type of the working machine to be mounted. For example, in the vehicle speed correction control shown in FIGS. 5 to 8, the set value of the HST rotation speed setter 23 corresponding to the operation position of the main shift lever is set in accordance with the type and size of the work machine to be mounted. change. In addition, the setting of the working height also depends on the type of working machine and the like.

If the working machine to be mounted is special, it is unavoidable to artificially change such set values every time the working machine is mounted. Wants to naturally determine various setting values for each control when it is mounted. For that purpose, means for specifying the work machine when the work machine is mounted is required. In the present embodiment, the work machine to be specified is a rotary cultivator (most often used in agricultural tractors), and as the specifying means, detection means originally provided in the HST is used. In addition, since it is not necessary to newly provide a dedicated detecting means, the cost can be reduced.

Now, in order to specify the rotary cultivator in this embodiment, it is necessary to detect a remarkable feature when the rotary cultivator is mounted. As a remarkable feature when the rotary tiller is mounted, a strong back pressure is applied to the HST output shaft 3b. That is, the tilling work by the rotary cultivator is always performed at the time of forward running. Therefore, the lever angle sensor S5, the swash plate position sensor S1, etc. It should detect that the plate is in the forward position, and the forward hydraulic pressure sensor (forward hydraulic pressure detecting means) S3 provided in the HST 3 should also detect the operating hydraulic pressure flowing for forward drive. Nevertheless, in HST3, the reverse hydraulic pressure sensor (reverse hydraulic pressure detecting means) S4
In the case where the detection of the working oil pressure appearing during reverse travel is recognized, it is determined that the cause is the back pressure caused by the mounting of the rotary tiller, and at this time, it is determined that the rotary tiller is mounted, and various controls are performed. Is set to a value corresponding to when the rotary tiller is mounted.

The procedure for determining whether to mount the rotary tiller will be described with reference to the flowchart of FIG. here,
Various controls (eg, governor speed control, work implement height control, etc.) when various set values (eg, load factor set value, work height set value, etc.) are set in response to the installation of the rotary cultivator Rotary control is performed, and the controller C sets a rotary control flag for starting the rotary control routine. That is, the flag for rotary control is 1 (FLAG for rotary tilling =
At the time of 1), the rotary control routine is started.

First, under the initial setting (St21),
Rotary control flag is 0 (FLA for rotary tilling)
G = 0) (St22), and when the automatic mode is selected by the automatic / manual mode changeover switch SW4 (St23), the one-touch lifting / lowering switch is set to “lower” in order to determine whether the working machine is in the working state. ”Is set. In the case of the “lower” setting (St24), it is determined that the work implement is in the working state, and the rotary tilling flag is set to 0 (FLAG for rotary tilling =
0) (St25), a series of sequence controls associated with the one-touch up / down switch being "down", that is, being in a working state, is performed (St26).

Subsequently, the procedure proceeds to a procedure for determining whether or not the working machine is a rotary cultivator. That is, the lever angle sensor S5
It is confirmed that the HST operation lever 9 is at the forward position by reading the detection value of (S27), and further, by reading the detection value of the swash plate angle sensor S1, the swash plate position (HST) is read.
If it is confirmed that the position of the movable swash plate of the hydraulic pump P is on the forward side (St28), it is determined that the vehicle is driving forward. Although it is conceivable that forward drive is determined by detection of any one of the sensors, it is assumed that an error may occur between the position of the swash plate and the set position of the HST operation lever 9, and a plurality of The forward drive is determined by sensor detection.

When it is detected that any one of them is in the neutral or reverse position, (St27 + a or St28)
+ A), there is a possibility that the vehicle is driving backward, so at this time, the automatic / manual mode switch S
Even when W4 is automatically set, the control mode is switched to the manual mode (St33), and for the vehicle speed operation and the like, the operator controls the vehicle speed while watching the display of the load factor and the speedometer. And the height of the working machine is adjusted.

When it is determined that the forward drive is performed based on the position of the HST operation lever 9 and the position of the swash plate, the forward working pressure detection value (FP) detected by the forward pressure sensor S3 of the HST 3 and the forward pressure sensor S4 determined by the reverse pressure sensor S4. The reverse operating pressure detection value (RP) is read (St29), and a comparison operation between the two sensor detection values FP and RP is performed. Here, when the reverse operating pressure detection value RP is larger (or very large) than the forward operating pressure detection value FP (St30), the operating pressure exhibits the characteristic in the reverse driving state. Become. Note that only the reverse operating pressure detection value RP is read and R
If P> 0, it may be determined that the vehicle is in the reverse drive state with respect to the operating pressure.

Here, whether or not the work implement is actually driven is detected by ON / OFF of the PTO clutch switch SW5. When the state where the PTO clutch is ON is confirmed (St31), the work vehicle itself is in the forward drive state, but the reverse drive state with respect to the operating pressure of the HST is caused by mounting and driving the rotary tiller. In this state, a back pressure is applied to the output side of the HST3, and when this state appears, it is determined that the mounted work machine is a rotary cultivator, and the controller C determines a rotary cultivation flag. Is set to 1 (FLAG for rotary tilling = 1) (St32), and the routine proceeds to a routine for rotary tilling (St33). If the PTO clutch is off, it is determined that the state of the operating oil pressure is abnormal, and the process proceeds to another routine (S
t31 + a).

When the reference driving pressure is not detected at the HST output side in the working state when the forward drive is set (the working machine is driven "down") (ie, the reverse hydraulic pressure sensor S4 When it is judged from the detection state of that it is not the time when the rotary tiller is mounted), when the other work equipment is mounted,
Alternatively, it is determined that the work machine is not mounted, and in the present embodiment, the process is shifted to a manual control routine (St34), and, for example, the vehicle speed operation and the work machine field height adjustment are manually performed. The load factor and working height are set uniformly when a non-rotary cultivator is installed, and a general automatic control routine other than rotary tilling is provided. At this time, the process may shift to this control routine.

As described above, when the forward running of the work vehicle is started in the state where the automatic / manual mode switch SW4 is set to the automatic mode, the operating pressure of the HST is immediately detected to determine whether or not the rotary tiller is mounted. Is determined and the control (rotary control) corresponding to the rotary cultivator is automatically performed. Therefore, the operator does not need to perform the operation of setting the load factor, etc., so that the operation is easy and reliable. You can get a great Rotary work.

As described above, the rotary control includes various controls such as governor control and work height control. FIGS. 10 and 11 show the rotary control and the rotary tilling flag (FIG. 9) in FIG. Rotary tilling F
LAG) is replaced with a vehicle speed control and a vehicle speed control flag (vehicle speed control FLAG), and the vehicle speed control here means vehicle speed control as engine speed control by the electronic governor device 2. Included in the subject of rotary control. Therefore, the determination as to whether or not to perform the vehicle speed control as the rotary control shown in FIG. 10 is the same as the flow in FIG. 9 described above.

The vehicle speed control routine shown in FIG. 11 will be described. This is a routine for selecting vehicle speed control as rotary tilling control or selecting other vehicle speed control based on detection of a vehicle speed control flag. In the controller C, two tables (TABLE) for rotary tilling and non-rotary tilling are set in advance with respect to the set value of the load factor setting device 24 included in the electronic governor device 2 and the increase / decrease amount of the engine speed. If the vehicle speed control flag is 0 (FLAG = 0 for vehicle speed control) (that is, if the working machine is not a rotary cultivator),
t37), non-rotary tilling table (TABL)
E), and the load factor set value of the electronic governor device 2 is
In this embodiment, the vehicle speed is controlled to 95% (St38) and governor control is performed based on the set load factor.

If the vehicle speed control flag is 1 (FLA for vehicle speed control)
If G = 1) (St35), the rotary tilling table (TABLE) is read, and in the electronic governor device 2, the load factor is set to 97% in this embodiment,
The engine speed is reduced by 200 rpm from the set engine speed (St36). That is, in response to the rotary tilling, the engine speed is reduced and the torque is increased to increase the work load, and the engine output is controlled.

[0060]

According to the present invention, the control structure of the continuously variable work vehicle has the following effects by being configured as described above. First, with the control structure as described in claim 1, even if the actual shift position of the continuously variable transmission is shifted from the set position by the shift position setting means due to conditions such as load and oil temperature. Since the output control of the continuously variable transmission is performed to correct (or approach) the actual rotational speed to the set rotational speed, the actual vehicle speed becomes a vehicle speed correctly corresponding to the shift position assumed and set by the worker. You can run at the vehicle speed that you envisioned.

Further, the corrected vehicle speed can be kept constant by combining with governor control and the like, and the working pitch (tiling pitch, seeding pitch, transplanting pitch, etc.) can be equalized with the assumed value. And good work becomes possible. In addition, not the manual operation of the shift position setting means by the operator, but the detection value of the rotation speed of the output shaft of the continuously variable transmission and the rotation speed of the output shaft corresponding to the set value of the shift position setting means. When an error from the set value is detected, the output control of the continuously variable transmission is automatically performed by the shift position correcting means, so that there is no need for the operator to perform a complicated vehicle speed correction operation while watching the vehicle speed. .

In the output control of the continuously variable transmission,
When the actual rotation speed is smaller than the set value of the output shaft rotation speed, the speed increase control is performed. However, according to the configuration of claim 2, in the case of an overload state or when the engine rotation speed is increased. When the engine speed is low enough to cause engine stall when viewed from the set rotation speed, the speed increase control is not performed, so that the engine stall that may be caused by the torque reduction accompanying the speed increase of the output shaft of the continuously variable transmission is avoided.

Further, as described above, the set value of the rotation speed setting means of the output shaft of the continuously variable transmission is set in accordance with the set position of the shift position setting means.
The output shaft of the continuously variable transmission corresponds to the combination of the continuously variable transmission and the auxiliary transmission, which are the main transmissions. Is set, and the operator obtains the correct vehicle speed according to the vehicle speed set artificially by assuming a certain vehicle speed and combining the shift position of the continuously variable transmission and the number of speed stages of the auxiliary transmission. This allows the operator to accurately obtain the desired vehicle speed over a wide range.

According to the fourth aspect of the present invention, it is possible to detect that a specific work machine is mounted on the continuously variable work vehicle. Between the time and the other cases, the operator sets setting values (for example, engine load setting value and working height setting value) for various controls (for example, control of engine output and control of working height) to the working machine. There is no need to change the operation accordingly, and control corresponding to the working machine is automatically performed.
Good work is obtained. In addition, the work machine can be specified by using the existing pressure detection means in the continuously variable transmission without using any other dedicated detection means for specifying the work machine, and the cost can be reduced. .

[Brief description of the drawings]

FIG. 1 is an overall side view of an agricultural tractor as an embodiment of a work vehicle according to the present invention.

FIG. 2 is a side view of a portion centering on a clutch housing and a transmission case in the agricultural tractor shown in FIG. 1;

FIG. 3 is a plan view of the same.

FIG. 4 is a block diagram of an HST control system according to the present invention.

FIG. 5 is a basic flowchart of HST output correction control according to the present invention.

6 is a control flowchart of FIG. 5 in which control for correcting an HST rotation speed set value based on the number of sub-gear stages is added.
It is a T output correction control flowchart figure.

7 is an HST output correction control flowchart in which control for correcting an HST rotational speed set value based on the number of sub-gears and the number of PTO gears is added to the control flowchart shown in FIG. 5;

8 is an HST output correction control flowchart in which control for limiting the speed increase control of the HST output shaft is added to the control flowchart shown in FIG. 5;

FIG. 9 is a control flowchart for automatically detecting the mounting of the rotary tiller and performing control for the rotary till.

FIG. 10 is a control flowchart for automatically detecting the mounting of the rotary tiller and controlling the vehicle speed for rotary tilling.

11 is a flowchart following the flowchart of FIG. 10, and is a flowchart of a vehicle speed control routine for changing a set value relating to vehicle speed control based on a determination as to whether or not rotary tilling is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operating part 2 Electronic governor device 3 HST (Continuously variable transmission) 3b HST output shaft 7 PTO shaft (power take-off shaft) 9 HST operation lever 10 Sub transmission lever S1 Swash plate angle sensor S2 HST rotation sensor S3 Forward pressure sensor S4 Reverse pressure sensor S5 HST lever angle sensor S6 Accelerator sensor 23 HST rotation speed setting device 24 Load factor setting device

Claims (4)

[Claims] 1. A continuously variable transmission and a control mechanism thereof, the control mechanism of the continuously variable transmission includes at least a shift position setting unit, a shift position detecting unit, a shift position correcting unit, and a shift position correcting unit. A continuously variable transmission type work vehicle comprising: a transmission output rotation number setting means for setting the rotation number of the output shaft of the continuously variable transmission according to the set value of the position setting means; and a transmission output rotation number detecting means. In the forward setting,
When an error occurs between the set shift output rotational speed and the detected shift output rotational speed, in order to correct the error, the output shaft control of the continuously variable transmission is performed using the shift position correcting means. A control structure for a continuously variable work vehicle. 2. An internal combustion engine and a control mechanism thereof, and a continuously variable transmission and a control mechanism thereof. The control mechanism of the internal combustion engine includes at least an engine speed detecting means and an engine speed setting means. , An engine load detecting means, and an engine load setting means, wherein the control mechanism of the continuously variable transmission includes at least a shift position setting means, a shift position detecting means, a shift position correcting means, A shift output rotational speed setting means for setting the rotational speed of the output shaft of the continuously variable transmission in accordance with the set value of the position setting means; and a shift output rotational speed detecting means. When an error occurs between the rotational speed and the detected shift output rotational speed, in order to correct the error, the output shaft control of the continuously variable transmission is performed using the shift position correcting means. In the control structure of a work vehicle, When the detected shift output speed is lower than the set shift output speed by a certain value or more, the detected engine load is larger than the set engine load, or the detected engine speed is in a range where engine stop may occur when viewed from the set engine speed. In this case, the control structure of the continuously variable transmission-type work vehicle is characterized in that the output shaft control of the continuously variable transmission is not performed by the shift position correcting means. 3. An internal combustion engine and a control mechanism therefor, a continuously variable transmission and a control mechanism therefor, wherein the control mechanism for the internal combustion engine comprises at least an engine speed detecting means and an engine speed setting means. , An engine load detecting means, and an engine load setting means, wherein the control mechanism of the continuously variable transmission includes at least a shift position setting means, a shift position detecting means, a shift position correcting means, A shift output rotational speed setting means for setting the rotational speed of the output shaft of the continuously variable transmission in accordance with the set value of the position setting means; and a shift output rotational speed detecting means. When an error occurs between the rotational speed and the detected shift output rotational speed, in order to correct the error, the output shaft control of the continuously variable transmission is performed using the shift position correcting means. In the control structure of a work vehicle, The transmission output speed setting means is configured to change a set value corresponding to a set speed stage of a subtransmission that can be set to a plurality of stages that are arranged in series with the continuously variable transmission. The control structure of a continuously variable work vehicle. 4. A hydraulic continuously variable transmission including at least a hydraulic continuously variable transmission and a control mechanism thereof, and a power take-out shaft for a working machine, wherein the hydraulic continuously variable transmission control mechanism includes at least a shift position setting unit; Shift position detecting means, shift position correcting means, shift output rotational speed setting means for setting the rotational speed of the output shaft of the continuously variable transmission according to the set value of the shift position setting means, and shift output rotational speed detection Means, a hydraulic circuit for forward drive and a hydraulic apparatus for reverse movement of the hydraulic circuit, wherein the power take-off shaft for the working machine has at least a power take-off shaft for detecting whether it is in a drive state or a non-drive state. In the continuously variable work vehicle having drive detecting means, the shift position setting means, the shift position detecting means, the shift output rotational speed setting means, the shift output rotational speed detecting means, and the forward drive hydraulic pressure are provided. Detection means When the work vehicle is determined to be in the forward state by one or more of the following, when the reverse drive hydraulic pressure detection means detects that the work vehicle is in the reverse state, the work state is determined by the specific work machine. A control structure for a continuously variable work vehicle, wherein the control structure is configured to determine that there is a vehicle, and to perform control corresponding thereto.