JPH0367502A - Hydraulic going up and down-controlling device of ground working car - Google Patents

Abstract

PURPOSE:To improve working accuracy by correcting temperature characteristics of proportional flux controlling valve from estimated result of oil temperature with oil temperature-discriminating part in controlling part. CONSTITUTION:Proportional flux controlling valve for rising 31 and proportional flux controlling valve 32 are connected to output side of controlling part 30 and electric current detectors 35 and 36 are installed, then discriminating part estimating oil temperature from detected electric current value is installed in the controlling part 30. Temperature characteristics of the proportional valves 31 and 32 are corrected from estimated result of oil temperature by the discriminating part and simultaneously ON-time of pulse signal required to obtain an objective flux is calculated and corrected, then outputted from the controlling part 30.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for a proportional flow control valve used in a hydraulic lifting control device for lifting and lowering a ground work machine connected to a tractor or the like. be.

[Prior art and its problems] Conventionally, when controlling a ground work machine connected to a tractor to raise and lower, a pulse signal is sent to the drive section of each proportional flow control valve for raising and lowering, and the ON time of the pulse signal is changed ( P.W.
However, as the oil temperature in the tractor's transmission case increases, the temperature of the solenoid coil of the flow control valve also increases, and this temperature increase causes the internal temperature of the solenoid coil to increase. There was a problem in that the resistance increased, and as a result, the output current with respect to the ON time decreased, making it impossible to secure the necessary flow rate.

[Means for Solving the Problems] This invention is proposed in view of the above-mentioned problems, and provides a hydraulic lift control device for ground-based work equipment that can always ensure a target flow rate and improve work accuracy. To this end, the following technical measures were taken.

That is, in a hydraulic lifting control device for a ground work machine equipped with an ascending proportional flow control valve 31 and a descending proportional flow control valve 32, the ON time of the pulse signal that energizes the solenoid of each proportional flow control valve 31, 32 and the solenoid are determined. An estimation determination unit is provided to estimate the oil temperature of the hydraulic oil from the output current flowing through the proportional flow rate control valve 31.
This is a hydraulic lifting control device for a ground-based work machine, characterized in that it is equipped with a control unit 30 that corrects the temperature characteristics of 32, calculates and corrects the ON time to ensure a target flow rate, and outputs the corrected value. be.

[Example code] Hereinafter, the present invention will be described in detail based on the drawings.

First, to explain the configuration, 1 is a tractor with an engine 2 mounted on the front of the machine body, the rotational power of the engine 2 is appropriately reduced by a transmission in a transmission case 3 behind it, and the power is transferred to the front wheels 4, 4 and 4. A hydraulic cylinder case 6 is mounted on the rear upper part of the mission case 3 at the rear of the aircraft, which transmits power to the rear wheels 5.5.
Lift arms 8, 8 are rotatably pivotally attached to the left and right sides of the. Reference numeral 10 denotes a rotary tiller, which is connected to the tractor 1 through a three-point link mechanism consisting of a top link 11 and a lower link 12, 12 so as to be movable up and down.

The rotary tilling device 10 includes a tilling section 14, a main cover 15 that covers the tilling section 14, a rear cover 16 that is rotatably pivotally attached to the rear end of the main cover 15, and the lower edge of the rear cover 16 is placed on the ground. Perform deep plowing work without making sliding contact.

FIG. 2 is a block diagram of a control device that hydraulically controls this rotary tilling device to, and its details will be explained based on this block diagram.

Ground height setting device 19 attached to the rotating base of the hydraulic control lever 18 of the tractor 1. A tillage depth setting device 20 for setting the plowing depth of the rotary tillage device 10. A ground height detector 25 attached to the rotating base of the lift arm 8 on the − side and a rear end of the main cover 15 of the rotary tillage device 10. The plowing depth detector 26 is installed and detects the plowing depth of the rotary tillage device [10] by detecting the rotation angle of the rear cover 16.
A control unit 3 consisting of a CPU via an A/D converter 27, respectively.
0, and the output side of this control section 30 is connected to an ascending proportional flow control valve 31 and a descending proportional flow control valve 32, which constitute a hydraulic elevation control device. The proportional flow rate control valves 31 and 32 have a pressure oil flow opening area provided in the spool that changes in proportion to the current value energized to the solenoid of each control valve 31 and 32, and the detected value relative to the set value. 35 and 36 are configured such that a current proportional to the magnitude, that is, a deviation, is output from the control unit 30, and a pulse current with a pulse width proportional to the current value is energized to each solenoid. A current detector is interposed between the valves 31 and 32 and detects the current value flowing through the solenoids of each proportional flow control valve 31 and 32. A determining section is provided within the control section 30 to estimate the oil temperature from this detected current value.

Further, reference numeral 37 is a switch for forcibly raising and lowering that is directly connected to the control unit 30, and when this switch 37 is turned on,
Rotary tillage device connected to tractor 1 by turning OFF! 10 can be forcibly moved up and down.

Next, the operation of this embodiment will be explained based on the flowchart shown in FIG. The procedure shown in this control flow is a control program stored in the memory of the control unit 30.

Taking depth control (plowing depth control) as an example, during plowing work, the plowing depth is set by the plowing depth setting device 20,
The tilling depth is detected by the tilling depth detector 26, and the tilling section 1 of the rotary tilling device W110 is always set at the set depth.
Control is performed so that the number 4 is positioned. Proportional flow control valve 3
1. During the operation of 32, the current flowing through the solenoid of the control valve 31 (or 32) is detected by the current detector 35 (or 36).
CP is determined from the ON time of the pulse signal for driving the control valve detected at ) and sent from the control unit 30 and this detected current.
The temperature of the hydraulic oil is estimated by the oil temperature determination section in U (step ■■■).

If there is a difference between the plowing depth set value and the plowing depth detection value, an output request command is issued (step ■), and if the plowing depth has become too deep and a raise command is issued to make it shallower, the The target flow rate is calculated, and at the same time, the temperature characteristics of the rising proportional flow control valve 31 are corrected from the estimated temperature, and the target current value to be passed through the proportional flow control valve 31 is determined (step
■).

Then, the ON time of the pulse signal is set to obtain the a standard flow rate by taking into account the amount of change in resistance of the flow rate control valve 31 and the change in temperature characteristics (step ■).
Current is applied to the solenoid (step ■).

It should be noted that for the descending side output, a comparison operation similar to the above-mentioned operation is performed (step ■@).

After the target current value is determined, an ON time is set and current is caused to flow through the descending proportional flow rate control valve 32.

Figure 4A shows the waveform of the pulse signal, and Figure 4C shows the current flowing through the proportional flow control valve and the detected current value, respectively. The dotted line in the figure shows how the current decreases due to the influence of the rise in oil temperature.

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

In other words, even if the hydraulic oil in the transmission case rises, the oil temperature determination section in the control section 30 estimates the oil temperature and determines the amount of change in the internal resistance of the solenoid of the proportional flow control valve and the characteristics of the proportional flow control valve. Taking fluctuations into consideration, calculates the ON time of the pulse signal necessary to obtain the target flow rate, and outputs a set pulse signal from the control unit 30 to the drive unit that drives the solenoid of the flow control valve. Therefore, it is less affected by the temperature rise of the hydraulic oil unlike in the past, and it is possible to control the elevation of the ground work machine with improved accuracy.

[Brief explanation of drawings]

The figure shows an embodiment of the present invention, and the 11th! I
2 is an overall side view, FIG. 2 is a block diagram, FIG. 3 is a flowchart, FIG. Description of code Tractor engine mission case Height above ground setting device Tilling depth setting device Height above ground detector Tilling depth detector Control section Proportional flow control valve for ascending Proportional flow control valve for descending

Claims (1)

[Claims] Rising proportional flow control valve 31 and descending proportional flow control valve 3
In the hydraulic lifting control device for ground work equipment equipped with An estimation discrimination section is provided, and based on the estimation result of the oil temperature by this discrimination section, the proportional flow rate control valve 31,
A hydraulic lifting control device for a ground-based work machine, characterized in that a control unit 30 corrects temperature characteristics of a ground work machine 32 and calculates, corrects, and outputs an ON time for ensuring a target flow rate.