JPH11332309A - Load controller of tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent engine stop and flatly finish the field face in operation by a tractor. SOLUTION: In this load controller of a tractor controlled so as to raise a working machine when detected size of engine load becomes larger than a previously set value, when raising output demand of the working machine is made at a frequency of a definite value or above, speed change position is shifted to low speed side. In this load controller of a tractor controlled so as to raise the working machine when detected size of engine load becomes a previously set value, lowering pattern is changed so as to be different from previous lowering pattern when the working machine is continuously raised by the above control to lower the working machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor load control device for controlling an engine load so as not to become too large during work.

[0002]

2. Description of the Related Art When a work is performed by connecting a ground work machine such as a cultivator to a tractor, determination is made based on plowing depth control for controlling the work machine to be at a fixed height with respect to the ground and engine speed. Load control for controlling the engine load to fall within a predetermined range is also performed. That is, normally, the height of the working machine is kept constant by the plowing depth control, and when the engine load becomes large, the plowing depth control is temporarily released, and the working machine is raised by the load control to reduce the engine load. Then, when the engine load is returned to the normal state after the work implement has been raised by the load control, the work implement is lowered and returned to the plowing depth control near the target plowing depth value.

[0003] In the above load control, when the working machine after ascending is lowered at a stretch to near the target plowing depth, the engine load sharply increases and the working machine rises again. In order to prevent this, there is known a technique in which the working machine is lowered stepwise while alternately repeating lowering and lowering stop.

[0004]

By the way, in the field, there are both hard and soft soils in the soil. Generally, an increase in engine load during work is when a hard place in the soil is encountered. In such a case, the work implement can be lowered to the target cultivation depth value after passing through even a hard place of the soil. However, after the work implement rises due to the load control, when the work implement is lowered, the engine load increases again, and the work implement may rise immediately. When such a situation occurs continuously, it means that not only a hard place in the soil has been encountered, but also the work condition is not suitable for the conditions of the field. Therefore, even if the work is continued as it is, the work machine simply repeats ascending and descending, and the field scene is finished unevenly.

Accordingly, the present invention is to prevent stalling and to make a field scene flat by always performing work in an appropriate state when performing tractor work using both plowing depth control and load control. Is an issue.

[0006]

Means for Solving the Problems In order to solve the above problems, the present invention is configured as follows. That is, the tractor load control device according to the first invention detects the magnitude of the engine load, and controls the work implement to rise when the engine load becomes larger than a preset value. In the above, when the demand for increasing the output of the work implement is issued at a frequency higher than a certain level, the shift position is shifted to a lower speed side instead of raising the work implement.

A load control device for a tractor according to a second aspect of the present invention detects the magnitude of an engine load and controls the work implement to rise when the engine load reaches a preset value. The apparatus is characterized in that when the work implement rises continuously by the above control, the descending pattern is changed to be different from the previous descending pattern to lower the work implement.

Further, a tractor load control device according to a third aspect of the present invention detects a magnitude of an engine load, and controls the work implement to be raised when the engine load reaches a preset value. In the apparatus, after lowering the work implement by the above control, when lowering the work implement, the work implement is configured to be lowered stepwise while alternately repeating lowering and lowering stop, and while the work implement is being lowered. When the ascending output request is issued continuously, one or both of the descending amount per one stage and the descending stop time at the time of the subsequent lowering of the work machine are changed from those at the time of the previous lowering of the work machine. .

[0009]

Preferred embodiments of the present invention will be described below with reference to the drawings. The tractor 1 shown in FIG.
A four-wheel drive vehicle including a pair of left and right front wheels 2, 2 and rear wheels 3, 3, wherein an engine 5 is mounted at a front portion of the body,
A clutch case 6 for housing a main clutch is provided on the rear side, and a transmission case 7 for housing a forward / reverse transmission, a main transmission, an auxiliary transmission, and the like is provided behind the clutch case 6.

[0010] Fenders 8, 8 are attached from the front to the upper part of the left and right rear wheels 3, 3, and a seat 9 is provided between the left and right fenders. A steering handle 10 for steering the front wheels 2 is provided in front of the seat 9. Further, on the side of the seat 9, a shift lever 11 for switching a shift position, a position lever 12 for raising and lowering the work implement, a tillage setting dial 13 for setting a tillage depth when a rotary tillage device is connected as a work implement, load control A mode switch 14 and the like are provided.

At the rear of the machine body, lift arms 16 and 16 are provided, which are vertically moved by an elevating hydraulic cylinder 15. A lift arm is provided between an end of the lift arm and an intermediate portion of a lower link 17 for mounting a working machine. They are connected by rods 18,18. By raising and lowering the lift arms 16, 16, the working machine 20 supported by the three-point link mechanism constituted by the lower links 17, 17 and the top link 19 moves up and down. Lift arm 16,
The rotation angle of 16 is detected by the lift arm sensor 21.
Note that one of the lift rods 18 (the left side in the illustrated example) is a hydraulic cylinder for tilting left and right, and the tilt of the working machine is adjusted by expanding and contracting the hydraulic cylinder. In the figure, a rotary tilling device is connected as a work machine 20, and the rotary tilling device is provided with a depth sensor 22 for detecting an actual tillage depth.

FIG. 2 is a diagram showing a transmission mechanism of the tractor.
The rotational power of the engine 5 is input to the transmission case 7 via the main clutch 23 in the clutch case 6 so that the power can be transmitted and received. The rotation speed of the secondary shaft of the main clutch 23 is detected by the engine speed sensor 24. The power input to the transmission case 7 is transmitted and branched to two systems, a driving power for driving the front wheels and the rear wheels, and a PTO driving power for extracting external power.

The traveling driving force is controlled by a multi-plate hydraulic clutch type forward / reverse switching device 25 and a synchromesh type main transmission 2.
6, and a synchromesh type auxiliary transmission 27. The forward / reverse switching device 25 includes a forward speed, a reverse speed,
And switch to neutral. The main transmission 26 is "first speed"
It has four gear positions of "4th speed", "1st speed" and "2nd speed"
Is changed by the variable speed hydraulic cylinder 28A, and "3rd speed" and "4
"Speed" is switched by the transmission hydraulic cylinder 28B. The piston operation amounts of the transmission hydraulic cylinders 28A, 28B are detected by main transmission position sensors 29A, 29B, respectively. The sub-transmission 27 has four shift positions of "ultra low speed", "low speed", "medium speed", and "high speed", and switches between them manually.
By the combination of the main transmission 26 and the auxiliary transmission 27,
As shown in the table of FIG. 3, 16 shift steps can be obtained for both forward and reverse.

A part of the shifted power is supplied to the rear wheel differential device 30.
To drive the left and right rear wheels 3, and the remaining power is transmitted to the front wheel differential device 31, and the left and right front wheels 2, 2
Drive.

On the other hand, the PTO driving force is transmitted by the PTO transmission 3
2 and is taken out to the PTO shaft 33 projecting rearward from the rear part of the transmission case 7. A transmission shaft 34 to the work machine 20 is removably and operatively connected to the protruding portion of the PTO shaft 33.

As shown in FIG. 4, the shift lever 11 for switching the shift position of the main transmission 26 and the auxiliary transmission 27 is provided with a push button type speed change switch 35 and a deceleration shift switch at the handle portion. A switch 36 is provided to operate the entire lever along an H-shaped guide groove 37. When the speed change switch 35 is pressed, the main speed is sequentially shifted up from "1st speed" to "4th speed", and when the speed reduction switch 36 is pressed, the main speed is changed from "4th speed" to "1 speed".
Shift down sequentially to the "speed" side. The main clutch 21
By operating the shift lever 14 to each shift position of the guide groove in a state where the gear is turned off, the sub-shift is set to “ultra low speed (LL)”.
Switching is made between "low speed (L)", "medium speed (M)" and "high speed (H)".

When the rotary tilling device is connected to the tractor, the tilling depth control for keeping the tilling depth constant and the load control for preventing the engine load from becoming too large are performed together. FIG. 5 is a block diagram of these tillage depth control and load control systems. The input side of the controller 40 is connected to the lift arm sensor 21, the depth sensor 22, the engine speed sensor 24, the main speed change position sensors 29A and 29B, the cultivation depth setting dial 13, the speed change switches 35 and 36, and the load control mode switch 14. ing. The output side of the controller 40 is provided with the transmission hydraulic cylinders 28A, 28B.
Transmission solenoids 42, 43, 4 for driving the control valves
4, 45, an ascending solenoid 46 for driving a control valve of the elevating hydraulic cylinder 15, a descending solenoid 47, and a notification buzzer 48 are connected.

The control valves of the transmission hydraulic cylinders 28A and 28B and the lifting hydraulic cylinder 15 are proportional pressure control valves.
The output current value to the solenoid that drives these valves is calculated by multiplying the standard value by a coefficient for correcting the variation of the hydraulic equipment and a coefficient for correcting the variation of the circuit board of the controller 40 itself. These coefficients are stored in the EEPROM 50. For this reason, even if the board | substrate of a controller is exchanged, the controller 50 can be made to function normally immediately.

First, the engine load is determined based on the engine speed detected by the engine speed sensor 24. If the engine load is equal to or less than a predetermined value, the cultivation depth control mode is set. In the tillage depth control mode, the actual tillage depth value detected by the depth sensor 22 is output to the ascending solenoid 46 and the descending solenoid 47 so as to match the target tillage value set by the tillage depth setting dial 14. Raise and lower the work machine.

When the engine load is equal to or more than a predetermined value, the mode is switched to the load control mode. In the load control mode,
The work implement is once raised to a predetermined height at which no load is applied to the work implement, and at that position, a predetermined time Tw (for example, Tw = 0.
After holding for 1 second), the work implement is lowered to the target plowing depth. At this time, as shown in the graph of FIG. 6, the work machine is lowered stepwise while alternately repeating lowering and lowering stop. The first step reduction width is a reduction width of 1 / X (X is arbitrary) of a difference between the lift arm sensor value Lf at the time of stopping the rising output and the lift arm sensor value Ld corresponding to the target plowing depth value. The reduction width after the second stage is 1 / X of the difference between the lift arm sensor value at the end of the previous stage and the lift arm sensor value Ld corresponding to the target plowing depth value.
That is, the decreasing width is gradually reduced. Then, when the working machine has sufficiently approached the target plowing depth position, the work implement is directly lowered until the lift arm sensor value Ld corresponding to the target plowing depth value is reached. The solid line in the graph of FIG.
The case where the descent stop time Tk = 1 second is indicated, and the broken line indicates the case where the solid line X = 3 and the descent stop time Tk = 0.5 second.

Further, the engine load is determined by estimating that the engine speed sensor value is stabilized every time the output of the descent is stopped at each stage. When the engine load is equal to or more than a predetermined value, the working machine is moved to the predetermined level. Raise again to height. Then, as described above, after holding at that position for a certain period of time, the work machine is lowered to the target plowing depth value. Change one or both of the descent stop times. FIG. 7 is a flowchart of the control.
And In the flowchart, the output pattern at the time of the first descent is displayed as "normal load", and the output pattern at the second and subsequent descents is displayed as "high load". For example, in the case of "normal load", the load is decreased in the output pattern shown by the solid line in the graph of FIG.

When the work machine is raised by the load control, the request for continuously raising the work machine without returning to the cultivation depth control means that not only a hard place in the soil is encountered but also that There is a great possibility that the engine is overloaded at the shift position. Therefore, even if the work is continued as it is, it is expected that the work implement lifting request will be issued again. Therefore, in order to prevent the work machine from lowering unnecessarily, the lowering amount per one stage is reduced from the second and subsequent lowering times, and the engine load is determined in small increments. Even if the descending amount per stage is reduced, the descending stop time Tk is shortened instead, so that the total time required for descending the working machine from the predetermined height to the target plowing depth value is reduced. Can be shortened.

As shown in the flow chart of FIG. 8, when there is a request for ascending three times within six seconds during the load control, the main speed is shifted down by one stage, and this is changed to the buzzer 48.
To inform. If the ascending request is made three times or more in six seconds, the main shift may be shifted down by one step. The time when the work implement rises continuously due to the load control is when the work implement is descending or when the descending ends and rises again within a certain time. Hereinafter, load control is performed in the same manner, and if necessary, the gear is shifted down by one stage. In this way, by performing the work at an appropriate shift position according to the engine load, engine stall can be prevented, and the field scene can be finished flat by preventing the working machine from repeatedly rising and falling.

The load control mode switch 41 is a switch for switching between a mode in which the work equipment is lifted and automatic deceleration in load control are performed, a mode in which automatic deceleration is not performed, and a mode in which neither (no load control) is performed. When the load control mode switch is set to a mode in which automatic deceleration is not performed, automatic deceleration is not performed even if the number of times of request for ascent is satisfied. By providing the load control mode switch 41, it is possible to carry out load control according to the preference of the operator.

Further, when the sub-shift is neutral, that is, when the vehicle is stopped, automatic deceleration is not performed by the load control. This is to prevent a meaningless downshift when performing adjustment or various settings by grounding the work implement before work, for example.

The load control of this embodiment employs a descent pattern in which the work machine is lowered step by step while alternately repeating the descent and the descent stop. A descending pattern to be changed or another descending pattern may be adopted.

[0027]

As is apparent from the above description, the load control device for a tractor according to the present invention does not raise the working machine but raises the speed when the demand for increasing the working machine output is issued more than a certain frequency. By shifting the position to the low speed side, it is possible to always work at the appropriate shift position, prevent stalling, and eliminate the need for the work machine to repeatedly rise and fall, so that the field scene can be finished flat. Became.

[Brief description of the drawings]

FIG. 1 is a side view showing a working state by a tractor.

FIG. 2 is a diagram of a transmission mechanism.

FIG. 3 is a table showing a relationship between the number of shift speeds, a shift position of a main shift, and a shift position of a sub-shift.

FIG. 4 is a perspective view of a shift lever.

FIG. 5 is a block diagram of a tillage depth control system and a load control system.

FIG. 6 is a graph showing a descending output pattern.

FIG. 7 is a first flowchart of load control.

FIG. 8 is a second flowchart of load control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tractor 2 Front wheel 3 Rear wheel 5 Engine 7 Transmission case 15 Elevating hydraulic cylinder 24 Engine speed sensor 26 Main transmission 27 Auxiliary transmission 28A, 28B Transmission hydraulic cylinder 40 Controller 41 Load control mode switch

Claims (3)

[Claims] 1. A load control device for a tractor for detecting the magnitude of an engine load and for raising the work implement when the load reaches a preset value, wherein the demand for the increase output of the work implement is not less than a certain value. A load control device for a tractor, wherein the shift position is shifted to a lower speed side instead of raising the work implement when the frequency is issued. 2. A load control device for a tractor that detects the magnitude of an engine load and controls the work machine to rise when the engine load reaches a preset value. A load control device for a tractor, characterized in that, when performing, the lowering pattern is changed to be different from the previous lowering pattern to lower the work implement. 3. A load control device for a tractor that detects the magnitude of an engine load and controls the work machine to rise when the engine load reaches a preset value. When the work machine is lowered, the work machine is configured to be lowered step by step while alternately repeating the lowering and the lowering stop. A tractor load control device characterized in that one or both of a descending amount per one stage and a descending stop time when the work machine descends are changed from those before the work machine descends.