JPH0789765B2 - Hydraulic lifting control device for ground work machine - Google Patents

Description

Description: [Industrial field of use] The present invention relates to a hydraulic lifting control device for lifting and lowering a ground work machine connected to a tractor or the like.

[Prior Art and its Problems] Conventionally, as shown in Japanese Patent Application No. 63-274104, this type of device has a proportional proportional flow control valve for ascending and a descending proportional flow control valve between a hydraulic cylinder driving a hydraulic lifting mechanism and a hydraulic pump. Each proportional flow rate control valve is installed, and the amount of current flowing to the solenoid of each proportional flow rate control valve is changed variously to change the spool opening amount, in other words, the pressure oil flow opening area, and to flow out the control valve. The amount of pressure oil to enter was controlled. In this case, the solenoid is configured to apply a current having a pulse width proportional to the current value.

In such a conventional device, when the current value to be supplied to the solenoid of the control valve is sharply increased on both the rising side and the falling side, the pressure or flow rate of the hydraulic oil does not follow the change in the current, and the input current After the target control amount is exceeded to secure the set pressure or flow rate, in other words, after the overshoot phenomenon occurs, the control state often stabilizes after a while, and it takes time for the control to stabilize. There was a problem.

[Means for Solving the Problems] The present invention is proposed in view of the above-mentioned problems, and an object thereof is to obtain a hydraulic lifting control device for a ground work machine capable of ensuring a stable control state in a short time. Is.

Therefore, the present invention takes the following technical means.
That is, the proportional flow control valve 31 for rising and the proportional control valve for falling
A hydraulic lift control mechanism having 32, a setting device 19 for setting the ground height of the ground work implement 10, and a detector 25 for detecting the ground height of the ground work implement 10 are provided, and the two proportional flow rates are provided. Control valve
In the hydraulic lifting control device for a ground work machine configured to control the flow rate to and from the proportional flow rate control valves 31 and 32 by changing the magnitude of the pulse current value energized to the solenoids 31 and 32, the solenoid When increasing the value of the current to be applied, a control unit 30 for limiting the rate of increase of the current value per pulse cycle is provided, which is a hydraulic lifting control device for a ground work machine.

[Embodiment] A practical example of the present invention will be described below with reference to the drawings.

First, the configuration will be described. 1 is a tractor equipped with an engine 2 at the front of the machine body, the rotational power of the engine 2 is appropriately reduced by a transmission in a mission case 3 behind the engine 2, and the power is transmitted to the front wheels 4, 4 and It is transmitted to the rear wheels 5, 5. A hydraulic cylinder case 6 is mounted on the upper rear part of the transmission case 3 in the rear part of the machine body, and lift arms 8, 8 are rotatably pivoted on both left and right sides of the case 6. Reference numeral 10 is a rotary tiller, which is movably connected to the tractor 1 via a three-point link mechanism including a top link 11, lower links 12, 12.

The rotary tiller 10 comprises a tiller 14, a main cover 15 that covers the tiller 14, a rear cover 16 that is pivotally attached to the rear end of the main cover 15, and the lower edge of the rear cover 16 is on the ground. Perform plowing work while making sliding contact.

FIG. 2 is a block diagram of a control device for hydraulically controlling the rotary tiller 10, and the details will be described based on this block diagram.

Ground height setting device 19 mounted on the rotation base of the hydraulic operation lever 18 of the tractor 1, plowing depth setting device 20 for setting the working depth of the rotary tiller 10, and mounting on the rotation base of the one-side lift arm 8. Height detector 25, rotary tiller 10
The cultivation depth detectors 26, which are attached to the rear end of the main cover 15 and detect the depth of cultivation of the rotary tiller 10 by detecting the rotation angle of the rear cover 16, are respectively connected via the A / D converter 27. Is connected to a control unit 30 composed of a CPU, and an ascending proportional flow rate control valve 31 and a descending proportional flow rate control valve 32 that constitute a hydraulic lift control device are connected to the output side of the control unit 30.

These proportional flow rate control valves 31, 32 are respectively controlled by the control valves 31, 32.
The flow opening area of the pressure oil provided on the spool changes in proportion to the value of the current supplied to the solenoid, and the control unit 30 outputs a current proportional to the detected value relative to the set value, that is, the deviation. A pulse current having a pulse width proportional to the current value is supplied to each solenoid.

Further, reference numeral 35 is a switch for forcibly raising and lowering which is directly connected to the control unit 30, and by turning the switch 35 ON and OFF, the rotary tiller 10 connected to the tractor 1 is forcibly moved up and down. Can be made.

Next, the operation of this embodiment will be described based on the flow chart shown in FIG. In the procedure shown in this control flow, the control program is stored in the control unit 30.

First, the rotary tiller 10 is controlled from the ascending side to the descending side, or in the opposite case, the output direction changes,
When this change is recognized, the output current memory value is once set to zero for initializing the state (step).

The difference between the set value by the ground height setter 19 and the detected value by the ground height detector 25, that is, when the deviation is obtained, the output current value is calculated, and the regulation that may energize the solenoid is regulated. The current value is obtained. In order to facilitate understanding, it is assumed that the minute single pulse to be added is represented by α, and the minute pulse α is sequentially added to determine the regulation current.

The magnitude of the required current value and the regulated current value obtained from the difference between the set value and the detected value is determined (step), and when the required current is equal to or greater than the regulated current, the regulated current value is set as the output current (step). On the contrary, when the required current is less than the regulated current value, the required current value is set as it is as the output current.

For example, in FIG. 4A, when the pulse width W required to secure the required current value i is 3α <W <4α, the pulse width is gradually increased to α, 2α, 3α, W. While sequentially outputting the pulse current having the maximum pulse width W, and when the pulse width required to secure the required current value i exceeds 4α as shown in FIG.
The pulse width is gradually widened, such as 2α, 3α, and 4α, and the pulse having the regulation value 4α is output and set as the output current.

In this manner, when the output current is determined, the rotary tiller 10 is then lowered or raised, or the proportional flow control valve 3 for raising is moved according to the direction of the output request.
1. Energize each solenoid of the proportional flow control valve 32 for lowering.

In this embodiment, as the ground height setting device and the ground height detector of the ground work machine, the so-called position control mechanism corresponds to the reference numerals 19 and 25, and the depth control mechanism corresponds to the reference numerals 20 and 26. Applicable

[Effects of the Invention] Since the present invention is configured as described above, it has the following technical effects.

That is, in a hydraulic lift control device including the proportional flow rate control valves 31 and 32, in particular, when the current suddenly changes when the current increases, a change in the pressure or flow rate on the output side with respect to a change in the input current. However, it may take time to stabilize the control due to overshoot of the target control amount. However, according to the present invention, when the current increases, one pulse period Each proportional flow control valve 31, regulated current by limiting the amount of current increase per
Since it flows to 32, it is possible to solve the conventional problems that the control goes too far and it takes a long time to stabilize.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is an overall side view, FIG. 2 is a block diagram, FIG. 3 is a flow chart, and FIG. ) Is a waveform diagram showing an increase rate of pulses. Explanation of code 1 …… Tractor 2 …… Engine 3 …… Mission case 19 …… Ground height setting device 20 …… Ground depth setting device 25 …… Ground height detector 26 …… Ground depth detector 30 …… Control Part 31 …… Proportional flow control valve for raising 32 …… Proportional flow control valve for lowering

Claims (1)

[Claims] 1. A hydraulic lifting control mechanism having a rising proportional flow control valve 31 and a falling proportional flow control valve 32, and a ground work machine 10.
And a detector 25 for detecting the ground height of the ground working machine 10, and a pulse current value for energizing the solenoids of the two proportional flow control valves 31, 32. In the hydraulic lifting control device for a ground work machine configured to control the flow rates of the proportional flow rate control valves 31 and 32 by changing the magnitude, when increasing the current value to be applied to the solenoid, one pulse period is used. A hydraulic lifting control device for a ground work machine, which is provided with a control unit 30 for limiting an increasing rate of a current value per hit.