JPH10313608A - Machine for work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve such an inconvenience that the operation of a hydraulic actuator becomes instable in the second half of a deceleration deviation range in the case of adopting an electromagnetic switching valve low in frequency characteristics. SOLUTION: At the time of gradually decelerating the extension/contraction operation speed of a lift rod cylinder from the stage that the deviation of a target value and a lift rod sensor value enters a prescribed set deviation range, the cycle of inching signals is fixed first, the extension/contraction speed is decelerated based on the subtraction of a duty, then the duty is fixed and the extension/contraction operation speed is decelerated based on the subtraction of the cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of work machines such as tractors.

[0002]

2. Description of the Related Art Generally, this kind of working machine includes:
In determining a duty value of an inching signal for intermittently operating an electromagnetic switching valve based on a deviation between a target position and a detection position of a hydraulic actuator, a deceleration deviation range in which the duty value is reduced at a predetermined reduction rate is set. There is. That is, when the operating hydraulic actuator is suddenly stopped, a large impact is generated based on the inertia. Therefore, the operation speed is gradually reduced from near the target position to stop the operation with less impact. .

[0003]

Conventionally, the cycle of the inching signal is fixed and the operating speed of the hydraulic actuator is controlled based on the change in the duty value. However, an electromagnetic switching valve having a low frequency characteristic is employed. In such a case, the responsiveness of the electromagnetic switching valve is reduced in the latter half of the deceleration deviation range, and there is a possibility that the hydraulic actuator may stop before the target position. Therefore, in the related art, the above-described disadvantage is avoided by increasing the cycle of the inching signal or widening the dead zone. However, when the cycle is increased, the ON / OFF switching of the electromagnetic switching valve becomes clear. There is a disadvantage that a large shock is transmitted to the aircraft at the time of inching or stopping, and when the dead zone is widened, there is a disadvantage that accuracy and responsiveness of position control are reduced.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has been made to solve these problems, and an electromagnetic switching valve for switching the operation of a hydraulic actuator is provided at a predetermined period. A working machine that intermittently operates with the inching signal of the above and determines the duty value of the inching signal based on the deviation between the target position and the detected position of the hydraulic actuator. In setting the deceleration deviation range for decelerating the speed, the period of the inching signal is fixed, the first deceleration deviation range in which the duty value is reduced at a predetermined reduction rate, and the duty value of the inching signal is fixed, and the period is set to a predetermined value. A second deceleration deviation range to be reduced at the reduction rate is set. In other words, after reducing the duty value at a constant cycle, the duty value is kept constant, and the operating speed of the hydraulic actuator can be reduced based on the reduction of the cycle. In comparison, the response of the electromagnetic switching valve can be improved. Therefore, it is not necessary to set a large cycle of the inching signal in advance or set a wide dead zone, and as a result, it is not possible to eliminate a disadvantage that a large shock is transmitted to the body at the time of inching or stopping, Control accuracy and responsiveness can be improved. Also, while feeding back the operation amount or operation speed of the hydraulic actuator,
There is provided feedback correction means for correcting the period or duty value of the inching signal based on the fed back operation amount or operation speed. That is,
The operating speed of the hydraulic actuator in the final deceleration stage may become unstable based on the weight of the work equipment, the operating oil temperature, the engine speed, the variation of the hydraulic equipment, etc. Since the cycle or duty value of the inching signal is corrected based on the inching signal, the hydraulic actuator can be smoothly stopped at the target position.

[0005]

Next, one embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling body of a tractor, and a working machine 3 such as a rotary is connected to a rear portion of the traveling body 1 via a lifting link mechanism 2 so as to be able to move up and down. The work machine 3 moves up and down with the vertical swing of a lift arm 5 that suspends the lifting link mechanism 2 via the lift rod 4, while a lift provided on one of the left and right lift rods 4. Rod cylinder 6
Are tilted left and right with the expansion and contraction of.

The lift rod cylinder 6 is connected to the hydraulic pump P via an electromagnetic switching valve 7 for lift rod, and an extension solenoid 7a and a reduction solenoid 7b for switching the electromagnetic switching valve 7 for lift rod.
Since intermittent driving based on the inching pulse is possible, the operating speed of the lift rod cylinder 6 can be controlled based on the duty setting (ON time / cycle) of the inching pulse. Reference numeral 8 denotes a lift cylinder for hydraulically operating the lift arm 5, and reference numeral 9 denotes an electromagnetic switching valve for the lift arm.

Reference numeral 10 denotes a control unit constituted by using a microcomputer. On the input side of the control unit 10, a lift rod sensor 11 for detecting the length of the lift rod cylinder 6 is provided, A tilt sensor 12 for detecting an angle, a tilt automatic switch 13 for turning on / off the tilt automatic control, a tilt setting potentiometer 14 for setting a target tilt for the tilt automatic control, and the like are connected via an input interface circuit, while being connected to an output side. Are solenoids 7a and 7 for extending and reducing the electromagnetic switching valve 7 for the lift rod.
b and the like are connected via an output interface circuit.

The control section 10 has an automatic tilt control function for automatically controlling the tilt of the work machine 3 based on a detection signal of the tilt sensor 12. Automatic tilt control includes “data input” for inputting a sensor signal and the like, “data set” for calculating a lift rod target value based on a tilt sensor value and a tilt setting volume value, a lift rod target value and a lift rod sensor value. "Data comparison" which determines the operation direction of the lift rod cylinder 6 by comparing the output data (cycle and duty of the inching pulse) to the telescopic solenoids 7a and 7b based on the deviation between the lift rod target value and the lift rod sensor value. ), “Feedback” for correcting output data based on the lift rod sensor value (offset processing), and “lift” for outputting an inching pulse corresponding to the output data to the telescopic solenoids 7a and 7b. It consists of subroutines such as , Below,
Of these subroutines, “lift rod output data set” and “feedback”, which are the main parts of the automatic tilt control, will be described with reference to flowcharts. In addition, since the control concept at the time of the extension operation and the reduction operation is substantially the same,
The description (flowchart) at the time of the reduction operation is omitted.

In the “lift rod output data set”,
First, the operation direction of the lift rod cylinder 6 is determined, and if the determination result is expansion or contraction, deviation data (deviation data = | target value−lift rod sensor value | +)
Based on a comparison between the deviation offset data) and the range data, the deviation data is set in any of the set deviation ranges {A range, B range (second deceleration deviation range), C range (first deceleration deviation range), and total flow range}. It is determined whether or not it is located. When it is determined that the flow rate is in the entire flow rate range (deviation data ≧ A range data + B range data + C range data−range offset data), the entire flow rate range flag is set, and the maximum value is set in the cycle data and the duty data. A preset maximum cycle and maximum duty) are set. In other words, when the deviation between the target value and the lift rod sensor value exceeds the C range maximum deviation c (deceleration start deviation), the maximum duty (100% in this embodiment) is used for the lift rod cylinder 6.
Is operated to expand and contract at a constant speed.

If it is determined that the deviation data is in the C range (A range data + B range data + C range data-range offset data> deviation data ≧ A range data + B range data-range offset data), the C range The flag is set, and the maximum cycle is set in the cycle data. The duty data is calculated using the following equation. Where D is duty data, H is deviation data, A is A range data, B is B range data, C is C range data, O is range offset data,
Dmax is the maximum duty, and Dmin is the minimum duty. D = [{H−B− (A−O)} / C] (Dmax−Dm
in) + Dmin That is, when the deviation between the target value and the lift rod sensor value is smaller than the maximum deviation c in the C range and equal to or larger than the maximum deviation b in the B range, the cycle is set to a constant (maximum cycle) and the duty is gradually increased. To reduce the expansion / contraction operation of the lift rod cylinder 6.

The deviation data is in the range B (A range data + B range data-range offset data> deviation data ≧
If it is determined that the data is (A range data), the B range flag is set, the minimum duty is set in the duty data, and the cycle data is calculated using the following formula. Here, T is cycle data, Tmax is a maximum cycle, and Tmin is a minimum cycle. T = [{H− (A−O)} / B] (Tmax−Tmi
n) + Tmin In other words, when the deviation between the target value and the lift rod sensor value is smaller than the B range maximum deviation b and equal to or more than the A range maximum deviation a, the duty is fixed (minimum duty).
In this range, the responsiveness of the electromagnetic switching valve 7 for the lift rod is reduced. Therefore, even if the duty is constant, the expansion and contraction of the lift rod cylinder 6 with the decrease in the cycle is performed. The operation speed is reduced in a relatively stable state.

Also, the deviation data is in the range A (deviation data <
If it is determined that the data is (A range data), the A range flag is set and the A range data is set as the deviation data. When the A range data is set as the deviation data, the B range determination becomes YES, so that the minimum duty is set as the duty data, and the following calculation data is set as the cycle data. Has become. T = (O / B) (Tmax−Tmin) + Tmin In other words, when the deviation between the target value and the lift rod sensor value is smaller than the maximum deviation a in the A range, the constant cycle (minimum cycle) and the constant duty (minimum duty) ), The lift rod cylinder 6 is extended and retracted to the target position.

On the other hand, in the "feedback", first, the operation direction of the lift rod cylinder 6 is judged, and if the judgment result is extension or contraction, the feedback timer set at the time of stopping and at the time of non-offset processing ends. A determination is made, and if the determination is YES, the feedback deviation (operation amount) is compared with a target L (minimum operation amount) and a target H (maximum operation amount). If the feedback deviation is equal to or larger than the target L and smaller than the target H, the feedback data and the feedback timer are set and the process returns to the main routine. If the feedback deviation is smaller than the target L, the acceleration offset is set. While executing the processing, if the feedback deviation is equal to or greater than the target H,
A deceleration offset process is executed.

In the acceleration offset processing, first, it is determined whether or not the B range data (fixed value) matches the range offset data. If the determination is NO, the range acceleration offset processing is executed. When it is determined, the duty acceleration offset processing is executed. In the range acceleration offset process, after adding the range offset data (upper limit value = B range data), the sum of the A range initial data (fixed value) and the range offset data is set in the A range data, and The sum of the C range initial data (fixed value) and the range offset data is set in the range data. That is,
When the operation amount fed back is small, the deviation data, the A range data (A range maximum deviation a) and the C range data (C range maximum deviation c) are offset in the increasing direction, so that the duty data increases in the C range. , The telescopic operation speed is increased based on the increase of the period data in the range B and the range A. In the range increase offset process of the present embodiment, the deviation data, the A range data, and the C range data are offset in the increasing direction as described above, but only the B range data (B range maximum deviation b) is reduced. The same operation can be obtained even if the offset is performed.

On the other hand, in the duty acceleration offset processing, after adding the duty offset data (upper limit = maximum duty−minimum duty), the sum of the minimum duty (fixed value) and the duty offset data is set in the minimum duty data. It has become. In other words, if the target operating speed does not come out even when the range offset data is increased to the upper limit value, the minimum duty is offset in the increasing direction. The expansion / contraction operation speed is increased.

In the deceleration offset processing, first, the minimum duty data is set to a minimum duty (fixed value).
It is determined whether or not it is larger than the threshold value. If the determination is YES, the duty deceleration offset processing is executed, while if the determination is NO, the range deceleration offset processing is executed. In the duty deceleration offset processing, after the duty offset data is subtracted (lower limit value = 0), the sum of the minimum duty (fixed value) and the duty offset data is set in the minimum duty data. That is, since the minimum duty data increased by the duty acceleration offset processing is offset in the decreasing direction, the range A, the range B
In the range and the C range, the expansion / contraction operation speed is reduced based on the decrease in the duty data.

On the other hand, in the range deceleration offset processing, after the range offset data is subtracted (lower limit value = 0), the sum of the A range initial data (fixed value) and the range offset data is set in the A range data. For C range data,
The sum of the C range initial data (fixed value) and the range offset data is set. That is, since the deviation data, the A range data and the C range data offset in the increasing direction in the range acceleration offset processing are offset in the decreasing direction, the expansion / contraction operation speed is reduced in the C range based on the decrease in the duty data. , B range and A range, the expansion / contraction operation speed is reduced based on the decrease of the cycle data. In the above description,
For convenience, the case where the range offset data and the duty offset data are 0 is a reference, but in this state, the deceleration offset processing does not function effectively, so that in the mounting state, the middle point of the offset processing range is set to the initial position. Each data is set.

In the apparatus configured as described above, when gradually decreasing the expansion / contraction operation speed of the lift rod cylinder 6 from the stage when the deviation between the target value and the lift rod sensor value falls within a predetermined set deviation range, first, After decelerating the expansion / contraction operation speed based on the subtraction of the duty while keeping the cycle of the inching signal constant, simply subtract the duty until the final deceleration stage in order to decelerate the expansion / contraction operation speed based on the duty reduction and the period subtraction. In this case, it is possible to eliminate the disadvantage that the expansion and contraction operation of the lift rod cylinder 6 becomes unstable in the latter half of the deceleration deviation range. In other words, utilizing the fact that the frequency characteristic of the electromagnetic switching valve 7 decreases in the latter half of the deceleration deviation range, the telescopic operation speed is reduced based on the subtraction of the period without changing the duty. Therefore, it is not necessary to set a large period of the inching signal in advance or set a wide dead zone in advance.
As a result, it is not possible to eliminate the inconvenience of transmitting a large shock to the aircraft at the time of inching or stopping,
The accuracy and responsiveness of the automatic tilt control can be improved.

Further, in order to feed back the operation amount of the lift rod cylinder 6 and to correct the cycle or duty of the inching signal in accordance with the fed back operation amount, it is assumed that the working machine weight, the operating oil temperature, the engine speed, etc. In addition, it is possible to solve the problem that the expansion / contraction operation of the lift rod cylinder 6 becomes unstable based on the variation of the hydraulic equipment, and as a result, it is possible to improve the stability and control accuracy of the automatic tilt control.

The present invention is, of course, not limited to the above embodiment, and it goes without saying that the present invention can be applied to an electromagnetic switching valve for switching the operation of a hydraulic actuator other than the lift rod cylinder. Further, in the above embodiment, the electromagnetic switching valve having low response performance is targeted. However, the present invention (including “feedback”) may be implemented with respect to the electromagnetic switching valve having high response performance. In addition, it is not possible to suppress the generation of the inching sound and the shock of the electromagnetic switching valve, and it is possible to improve the control accuracy.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a hydraulic circuit diagram showing an operation circuit of a lift rod cylinder.

FIG. 3 is a block diagram showing input and output of a control unit.

FIG. 4 is a flowchart showing a main routine of automatic tilt control.

FIG. 5 is a flowchart showing a “lift rod output data set”;

FIG. 6 is a flowchart showing a data set portion at the time of extension of “lift rod output data set”.

FIG. 7 is a timing chart showing the operation of the “lift rod output data set”.

FIG. 8 is a graph showing the operation of the “lift rod output data set”.

FIG. 9 is a flowchart showing “feedback”.

FIG. 10 is a flowchart showing a feedback part (including a deceleration offset processing part) at the time of decompression of “feedback”.

FIG. 11 is a flowchart showing a feedback part (acceleration offset processing part) at the time of expansion of “feedback”.

FIG. 12 is a graph showing a “feedback” offset process (deviation, A range maximum deviation a and C range maximum deviation c).

FIG. 13 is a graph showing an operation of “feedback”.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traveling body 3 Work implement 6 Lift rod cylinder 7 Electromagnetic switching valve for lift rod 10 Control part 11 Lift rod sensor

Continued on the front page (72) Inventor Shigeharu Kimura 667 Iida-cho, Oji-zu, Higashi-Izumo-cho, Yatsuka-gun, Shimane Prefecture Within Mitsubishi Agricultural Machinery Co., Ltd. (72) Satoshi Tamura 667 Iya-cho, Oji-zu, Higashi-Izumo-cho, Yatsuka-gun, Shimane 1 Mitsubishi Agricultural Machinery Co., Ltd.

Claims (2)

[Claims] An electromagnetic switching valve for switching the operation of a hydraulic actuator is intermittently operated with an inching signal of a predetermined cycle, and a duty value of the inching signal is set to
A working machine determined based on a deviation between a target position and a detected position of the hydraulic actuator, wherein the working machine includes:
In setting the deceleration deviation range for decelerating the operating speed of the hydraulic actuator, the period of the inching signal is made constant, the first deceleration deviation range in which the duty value is reduced at a predetermined reduction rate, and the duty value of the inching signal is made constant, A work machine in which a second deceleration deviation range for reducing the cycle at a predetermined reduction rate is set. 2. The apparatus according to claim 1, further comprising feedback correction means for feeding back the operation amount or operation speed of the hydraulic actuator and correcting the cycle or duty value of the inching signal based on the operation amount or operation speed fed back. Working machine.