JPH0458857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a work tool posture control device for a front loader.

(Prior Art) A front loader, which is attached to a tractor body and performs work, has a boom pivotably supported on the tractor body so as to be able to rise and fall freely, and a working tool such as a bucket is rotatably attached to the tip of the boom. A solenoid valve corresponding to each cylinder is installed in the hydraulic circuit of the boom cylinder and bucket cylinder that operate these booms and buckets, and these solenoid valves are used to raise and lower the boom, scoop the bucket, and rotate the bucket in the dumping direction. I try to control it.

In this type of front loader, when scooping up earth and sand, it is necessary to ground the bottom of the bucket horizontally to the ground. Therefore, there is a system that detects the attitude of the bucket tot during the lowering operation of the boom and controls the attitude of the bucket tot so that the bucket tot is in the target posture, that is, horizontally touching the ground when it touches the ground.

(Problem to be Solved by the Invention) However, in the past, attitude control was performed independently on the bucket cart side regardless of the descending speed of the boom, so there were cases where the bucket cart could not reliably land on the ground with the bottom horizontal.

In other words, when lowering the boom from a sufficiently high position, or when the bucket does not deviate significantly from the target attitude (bottom horizontal) even if the boom is not high enough,
It is possible to control the attitude of the bucket to make the bottom horizontal during the lowering operation of the boom, but if the boom is at a low position, due to the responsiveness of the bucket tot control system, the bottom will be horizontal by the time the bucket touches the ground. You may not be able to correct your posture.

In view of these conventional problems, the present invention changes the posture control speed of the work tool according to the height at the start of the downward movement when the boom is lowered, so that the work tool in the lowered position is always in the target posture. The purpose is to be in control.

(Means for Solving the Problems) The present invention detects the attitude of the working implement 13 at the tip of the boom 10 during the downward movement of the boom 10, and brings the working implement 13 into the target attitude at the lowered position. 13
In a work implement posture control device for a front loader that controls the attitude of When the height signal is low, the work implement 13
A speed control means 63 is provided for changing the attitude control speed of the work tool 13 so that the attitude control operation of the work tool 13 becomes faster.

(Function) Lower the boom 10 from the raised position and set the work implement 13 in the lowered position to the target posture (for example, horizontal grounding)
When the work tool 13 is
Measure the height at the start of the downward movement. Then, when the boom 10 moves to the lowering operation, the attitude of the working tool 13 is detected at the same time, and attitude control is performed so that the working tool 13 at the lowered position has the target attitude. Based on the height signal, the posture control speed is changed depending on the height so that the posture control operation becomes faster when the height of the work implement 13 is low. For example, this is a variable gain amplifier circuit 63.
This is done by By changing the attitude control speed of the work tool 13 in this manner, it is possible to maintain the work tool 13 in the target attitude at the lowered position.

(Example) Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. In FIG. 2, 1 is a tractor body, 2 is a front wheel, 3 is a rear wheel, 4 is a rear wheel fender, and 5 is a driver's seat. Reference numeral 6 designates a front loader, which includes a mast 8 that is detachably installed on both sides of the tractor body 1 via a mounting base 7, and a boom 10 that is pivoted to the upper end of the mast 8 via a pivot shaft 9 so as to be movable up and down. This boom 10
It consists of a boom cylinder 11 for raising and lowering the boom, a bucket (working tool) 13 rotatably supported on the tip of the boom 11 by a pivot 12, and a bucket cylinder 14 for rotating the bucket.

Reference numeral 15 denotes an inclination sensor for detecting the inclination of the tractor body 1, which is attached to the front loader 6 side, for example, the mast 8. Reference numeral 16 denotes an attitude sensor for detecting the rotating attitude of the bucket cart 13, which is attached to a bracket 17 on the back side of the bucket cart 13. These sensors 15 and 16 are constructed by incorporating a weight plate 21 and a potentiometer 22 into two divided chambers 19 and 20 within a box-shaped case 18, as shown in FIG. The weight plate 21 is attached to a rotating shaft 23 supported by the case 18, and the potentiometer 22 is configured to interlock with the weight plate 21 via the rotating shaft 22. The weight plate 21 responds to changes in the attitude of the bucket 13, and a voltage signal corresponding to the attitude is output from the potentiometer 22. In addition, room 19
Damper oil 23a is placed inside.

Reference numeral 32 denotes an angle sensor consisting of a potentiometer or the like, which is provided in conjunction with the pivot shaft 9 so as to detect the angle of the boom 10.

Reference numeral 24 denotes an operating device, and as shown in FIGS. 4 to 6, there is an operating lever on a case 25 mounted on the rear wheel fender 4 on one side of the driver's seat 5, which can be operated longitudinally, horizontally, and diagonally. 26, this operating lever 26
first and second potentiometers 27,
28 etc. is incorporated. That is, the operating lever 26
is pivotally supported on the movable frame 29 via a horizontal axis 30, and the movable frame 29 is supported on the case 25 side via a longitudinal axis 31. Using the two axes 31 as fulcrums, it can be operated in any direction as shown in FIG. Note that the operating lever 26 is elastically held at the neutral position by a spring (not shown).
The first potentiometer 27 constitutes a lifting command means for commanding the lifting and lowering of the boom 10, and
It is linked to the back and forth movement of the operating lever 26 via the horizontal shaft 30, and outputs a voltage command signal corresponding to the amount of operation of the operating lever 26. 2nd potentiometer 2
8 constitutes a dump/scoop command means for issuing a dump/scoop command to the bucket 13;
The operating lever 26 is connected to the front and rear shaft 31 via the movable frame 29.
It outputs a voltage command signal in conjunction with the left and right movement of the control lever 26 and in accordance with the amount of operation of the control lever 26. A push-button automatic switch 33 is provided at the upper end of the operating lever 26 to be turned on during automatic operation.

FIG. 7 shows a hydraulic circuit for the lift cylinder 11 and the bucket cylinder 14, where 34 is a first electromagnetic valve that controls the lift cylinder 11, and has an ascending solenoid 35 and a descending solenoid 36. A second solenoid valve 37 controls the bucket cylinder 14, and has a dump solenoid 38 and a scoop solenoid 39. Both of these electromagnetic valves 34 and 37 are of a flow rate proportional type.

FIG. 1 shows an electric circuit for driving and controlling the solenoid valves 34, 37. In FIG. 1, 40 and 41 are amplifier circuits, and 42 is a first discrimination circuit that discriminates the operating direction during lifting and lowering, and outputs a rising signal when the command signal from the first potentiometer 27 is larger than the reference value. death,
Further, a falling signal is output when the value is smaller than the reference value. 43 is a second discrimination circuit for discriminating the operating direction during dumping and scooping, and like the first discrimination circuit 42, it outputs a dump signal and a scooping signal, respectively, in response to the command signal from the second potentiometer 28. It's getting old.

44 is a rising solenoid drive circuit, 45 is a descending solenoid drive circuit, and these are the first discrimination circuit 42.
When a rising signal or a falling signal is received from the analog switch 46 or 47, the analog switch 46 or 47 is turned on to drive the rising solenoid 35 or the falling solenoid 36. 48 is a dump solenoid drive circuit, 4
9 is the scoop solenoid drive circuit, these are the second
When a dump signal or scoop signal is received from the discrimination circuit 43, the analog switch 50 or 51 is turned on and the dump solenoid 38 or scoop solenoid 3 is activated.
It is designed to drive 9.

52 is a sample/halt circuit that stores the attitude signal of the bucket 13 from the attitude sensor 16 when the automatic switch 33 is turned on. Reference numerals 53 and 54 designate analog switches, so that when the automatic switch 33 is off (manual mode), the analog switch 53 is turned on, and when it is on, the analog switch 54 is turned on via the NOT gate 55 to switch between manual and automatic mode. It's getting old. Reference numeral 55 denotes a mode changeover switch, which has a contact 56 for attitude holding mode and a contact 57 for horizontal grounding mode.
2 is sent to the deviation amplification circuit 59, and in the horizontal grounding mode, the analog switch 60 is turned on and the slope signal from the slope sensor 15 is sent to the deviation amplification circuit 59.
It is now being sent to

61 is the boom 1 based on the angle signal of the angle sensor 32.
This is a height calculation circuit that calculates the height of the bucket 13 at the start of the downward movement of 0, and these angle sensors 32
The height calculating circuit 61 constitutes a height measuring means 62. Reference numeral 63 is a variable gain amplifier circuit as a speed control means, which uses the height signal from the height calculation circuit 61 to control the bucket height when the bucket height is high.
The gain is configured to change so that the attitude control speed of No. 3 becomes slow and, conversely, becomes fast when it is low. 6
4 is an AND gate which turns on the analog switch 65 when a falling signal is received from the first discrimination circuit 42 in the horizontal grounding mode, and sends the deviation signal of the deviation amplification circuit 59 to the variable gain amplification circuit 63; The analog switch 67 is turned on via the NOT gate 66, and the deviation signal is directly transmitted to the second discrimination circuit 4.
3. The signal is sent to the solenoid drive circuit 48 or 49.

In the above configuration, when performing manual control, the automatic switch 33 of the operating lever 26 is left off;
All you have to do is operate the operating lever 26. By operating this operating lever 26 in the direction of the arrow shown in FIG.
It is possible to perform dumping, scooping, and complex operations that combine these (see Figure 8).

For example, when the bucket 13 performs a scooping operation, when the operating lever 26 is rotated toward the left scooping side, the second potentiometer 28 is operated via the horizontal shaft 31, and the resistance value is set according to the amount of operation. changes and a predetermined command signal is output. Then, the second discrimination circuit 43 discriminates the command signal and outputs the scoop signal, so the analog switch 51 is turned on and the second
A command signal from the potentiometer 28 is sent to the scoop solenoid drive circuit 49, and the scoop solenoid 39 is controlled by the scoop solenoid drive circuit 49.
is driven by a current proportional to the command signal, and the second solenoid valve 37 is switched to the rake side. Therefore, the second electromagnetic valve 37 switches to the scooping side with an opening proportional to the command signal, and the bucket cylinder 14 contracts, so that the bucket 13 performs a scooping operation around the pivot shaft 12.

During automatic control, the automatic switch 33 of the operating lever 26 is pressed to turn on, and the mode changeover switch 55 is used to switch between posture holding mode and horizontal grounding mode. When the automatic switch 33 is turned on, the analog switch 53 is turned off, and at the same time as the second potentiometer 28 is released, the analog switch 54 is turned on.

As shown by the solid line in FIG. 9, when the bucket 13 is dumped at the raised position of the boom 10 to discharge soil, etc., and when the bucket 13 is lowered and its bottom is horizontally grounded, the mode selector switch 55 is set to the horizontal position. Set to ground mode and operate the operating lever 26 in the downward direction. Then, as in the case of manual control, the lowering solenoid 45 is energized, the first solenoid valve 34 is switched to the lowering side, the boom cylinder 11 is contracted, and the boom 1 is moved at a speed proportional to the amount of operation of the operating lever 26.
0 starts the downward movement. In addition, in the horizontal grounding mode, the analog switches 60 and 65 are turned on and the analog switch 67 is turned off, so the deviation amplification circuit 5
9 determines the deviation between the attitude signal of the bucket truck 13 detected by the attitude sensor 16 and the inclination signal of the tractor body 1 detected by the inclination sensor 15, and sends the deviation signal to the variable gain amplification circuit 63. On the other hand, the angle sensor 32 indicates that the boom 10 is
Detects the angle of and sends the angle signal to the height calculation circuit 6
1 reads in, calculates the height of the bucket 13, and controls the gain of the variable gain amplifier circuit 63 based on the height signal. In this case, the bucket truck 13 has deviated significantly toward the dump side from the posture when it should touch the ground horizontally, but since the bucket truck 13 is at a relatively high position, the bucket truck 13's posture has been sufficiently shifted while descending to the lower limit. The gain should be such that it can be controlled. If the height of the bucket 13 is low, it is necessary to speed up the attitude control operation in order to quickly control the attitude of the bucket 13, and therefore the gain is increased by the height signal. The deviation signal amplified by a predetermined gain in the variable gain amplifier circuit 63 is sent to the second
The signal is sent to a discrimination circuit 43 to determine the direction in which the attitude of the bucket 13 should be controlled. In this case, since the bucket 13 is on the dump side, the second discrimination circuit 43 outputs a dumping signal and turns on the analog switch 51. Therefore, the deviation signal amplified by the variable gain amplifier circuit 63 is sent to the scoop solenoid drive circuit 49 via the analog switch 51 and drives the scoop solenoid 39 of the second solenoid valve 37. is switched to the rake side with an opening proportional to the deviation signal, the bucket cylinder 14 is contracted, and the bucket 13 is controlled to a posture in which it should horizontally touch the ground. Therefore, if the boom 10 descends to the lower limit,
Since the bottom of the bucket 13 is in horizontal contact with the ground, if the tractor body 1 is immediately moved forward thereafter, it is possible to scoop up earth and sand. Also, tilt sensor 1
Since the inclination of the tractor body 1 is detected in step 6 and the deviation between the inclination signal and the attitude signal of the bucket 13 is determined, the bottom surface of the bucket 13 can be reliably grounded even on a slope.

The height of the bucket 13 is measured as follows. That is, when the tractor body 1 is on a horizontal plane and the line connecting the bottom of the bucket 13 and the grounding points of the front and rear wheels 2 and 3 is horizontal as shown in FIG. Angle sensor 3
The angle indicated by 2 is θ ₀ , and the axis 12 of bucket 13 is
Let h ₀ be the height from to the pivot 9 of the boom 10.
Therefore, as shown in FIG. 10, the magnitude relationship of θ ₀ with respect to θ is determined from the angle signal of the angle sensor 32. If θ<θ ₀ , the height h of the bucket is
It is calculated using the formula h ₀ + Lsin (θ ₀ - θ), and conversely θ
> θ ₀ , it is calculated using the formula h ₀ −Lsin(θ−θ ₀ ). In addition, L is the axis 9, 12 of the boom 10.
It is the length between.

Note that the height of the bucket 13 can also be determined by attaching an inclination sensor to the base of the boom 10 or the like and detecting the inclination angle of the boom 10 with the inclination sensor.

If the bucket 13 is to be raised or lowered while maintaining its posture, the mode changeover switch 55 is set to the posture holding mode, and the automatic switch 33 is turned on. Then, the attitude signal of the bucket 13 detected by the attitude sensor 16 is sent to the sample and hold circuit 52.
is stored, the deviation amplification circuit 63 calculates the deviation between this signal and the attitude signal from the attitude sensor 16 that changes as the user moves up and down, and the deviation signal is sent to the subsequent stage via the analog switches 67 and 54, and is sent to the bucket 13.
controls the automatic switch 33 to maintain its on-state attitude.

In the embodiment, the bucket 13 is used as an example of the working tool, but the tool is not limited to the bucket 13, and may be a fork or other attachment. In that case,
If you want to be able to attach and detach the work tool at will and replace it, a mounting bracket is pivotally attached to the tip of the boom 10, and the work tool is attached to this mounting bracket with a pin or the like in a removable manner. If the attitude sensor 16 is provided on the bracket side, even if there are various working tools, there is no need to provide the attitude sensor 16 for each working tool, which is very convenient.

Further, the inclination sensor 15 may be attached to the tractor body 1.

Further, in the embodiment, the target attitude and horizontal grounding are shown, but the present invention can also be applied to cases where it is necessary to maintain a predetermined attitude in a descending position.

(Effects of the Invention) According to the present invention, the height of the work implement at the start of the descending operation is measured, and based on the height signal, the attitude control speed is changed so that the attitude control operation of the work implement becomes faster when the height is low. Therefore, no matter what height the work implement is lowered from, it is possible to control the work implement at the lowered position to the target posture.

[Brief explanation of the drawing]

The drawings illustrate one embodiment of the present invention, in which Fig. 1 is an electrical circuit diagram of the control system, Fig. 2 is a side view of the tractor, Fig. 3 is a sectional view of the sensor, and Fig. 4 is an operation diagram. Rear view of the device, Figure 5 is a sectional rear view of the same, Figure 6 is a view along the X-X arrow in Figure 5, Figure 7 is a hydraulic circuit diagram, Figure 8 is an explanatory diagram of the control position, Figure 9 is an action explanatory diagram, and FIG. 10 is a flowchart. 1...Tractor body, 6...Front loader,
10...Boom, 13...Bucket (work tool),
15... Tilt sensor, 16... Attitude sensor, 24
...Operating device, 26...Operating lever, 27, 28
...Potentiometer (command means), 34, 37
... Solenoid valve, 42, 43 ... Discrimination circuit, 59 ...
Deviation amplification circuit, 62... Height measuring means, 63...
Variable gain amplification rotation (speed control means).

Claims (1)

[Claims] 1. Operation of a front loader that detects the attitude of the working tool 13 at the tip of the boom 10 during the lowering operation of the boom 10, and controls the attitude of the working tool 13 to bring the working tool 13 into the target attitude at the lowered position. The tool posture control device is provided with a height measuring means 62 for measuring the height of the working tool 13 when the boom 10 starts its lowering operation, and a height signal from the height measuring means 62 is used to control the work tool 13 when the height is low. A work tool attitude control device for a front loader, characterized in that a speed control means 63 is provided for changing the attitude control speed of the work tool 13 so that the attitude control operation of the work tool 13 becomes faster.