JPH08224003A - Hydraulic pressure regulating device of tractor - Google Patents

Abstract

PURPOSE: To regulate various operating machines linked to a tractor in an optimal state. CONSTITUTION: This hydraulic pressure regulating device in a tractor having a position regulating mode and a draft regulating mode and capable of vertically moving and rotating a hydraulic lifting up and down mechanism by a command from a regulating part 18 consisting of a microcomputer to excite an solenoid valve 12 for lifting up and a solenoid valve 13 for taking down, is obtained by so as to make the relationship of a deviation with a flow rate a linear proportional relationship in the position regulating mode and the quadratic functional change of the flow rate to the deviation in the draft regulating mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for a tractor and is intended to control various working machines connected to the tractor in an optimum state.

[0002]

2. Description of the Related Art In recent years, computerization of hydraulic control devices for tractors has been undertaken. Draft control for lifting and lowering the plow and lifting and lowering of working machines while utilizing the rear cover of a rotary tiller as a working depth sensor. There are depth control for controlling, position control for operating the hydraulic operation lever back and forth and raising and lowering the working machine according to the operation amount, etc., and are electrically controlled.

[0003]

By the way, in the case of the above-mentioned conventional device, the control valve for operating the hydraulic lifting device is such that its flow rate characteristic is uniformly determined, and the control mode is changed. However, since the flow rate characteristics themselves did not change, it was difficult to say that optimum control could be performed depending on the type of work machine and work content, and there was the problem that accurate control could not be performed.

[0004]

The present invention has been proposed in view of the above-mentioned drawbacks, and has taken the following technical means. That is, it has a position control mode and a draft control mode, and is configured to control an ascending solenoid valve and a descending solenoid valve in response to a command from a control section to vertically rotate a hydraulic lifting mechanism. In the hydraulic control device of the tractor, in the position control mode, the flow rate characteristic is set so that the relationship between the deviation and the flow rate is substantially proportional, and in the draft control mode, the flow rate changes as a quadratic function with respect to the deviation. The hydraulic control device for a tractor is characterized in that the flow rate characteristic is set.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. First, the structure will be described. 1 is a tractor, and 2 and 3 are front and rear wheels of the tractor, respectively. Reference numeral 4 denotes a hydraulic cylinder case mounted on the upper part of the mission case 5, and in the hydraulic cylinder case 4,
A single-acting hydraulic cylinder is housed. Lift arms 6 and 6 are pivotally mounted on both right and left sides of the hydraulic cylinder case 4 so that the lift arms 6 and 6 can be moved up and down when hydraulic oil is supplied to and discharged from the hydraulic cylinder. are doing. 7 and 7 are lower links, 8 and 8 are lower links 7,
A lift rod 9 for connecting the lift arm 6 and the lift arm 6;
Is the top link.

Top link 9 and lower links 8, 8
A plow 10 is connected to the rear part of the three-point link mechanism consisting of, and a draft sensor 11 is provided on the upper rear part of the mission case 5, so that a compression force exceeding a predetermined value is applied to the top link 9 during plow work. A signal for raising the working machine is input to a control valve to be described later, and the plow 10 is interlocked so as to be raised.

The control valve comprises an ascending solenoid valve 12 and a descending solenoid valve 13. In this embodiment, the ascending solenoid valve 12 is an electromagnetic proportional type ascending proportional solenoid valve, and the descending solenoid valve 13 is used. Is composed of an electromagnetic proportional type proportional solenoid valve for lowering. Then, by controlling the value of the current supplied to these solenoid valves, the flow rate of the hydraulic oil proportional to the value of the current is secured.

FIG. 2 is a block diagram of the control system thereof. The potentiometer 14 mounted on the rotary shaft of the lift arm 6, the draft sensor 11, and the position lever for setting the lifting height of the working machine. A position setting device 15a attached to the rotating base of 15 and a draft setting device 16 for setting the draft force are connected to an A / D converter 17, respectively. The A / D converter 17 includes a control unit 18 including a microcomputer. They are connected, and current is applied to the ascending solenoid valve 12 and the descending solenoid valve 13 according to an instruction from the control unit 18.

Reference numeral 19 is a changeover switch for selecting a control mode, which is used by artificially changing it when the work content changes. The solenoid valves 12 and 13 are controlled according to the flow rate characteristics stored in the storage device of the control unit 18 by appropriately switching and using the changeover switch 19.
3 shows the case of position control, and FIG. 4 shows the case of draft control. In FIG. 3, the vertical axis shows the flow rate, the horizontal axis shows the deviation between the position setting value and the position detection value, and in FIG. 4, the vertical axis shows the flow rate, and the horizontal axis shows the deviation between the draft setting value and the draft detection value. Is represented.

In the case of position control, it is desirable that the flow rate with respect to the deviation linearly change so that the hydraulic lifting mechanism operates in proportion to the operation amount of the position lever 15.
Further, as is clear from the figure, since the dead zone a is set in the area where the deviation is minute, control is not performed in this range, and when the deviation exceeds the predetermined value b, the maximum flow rate (total amount) is flown.

In the case of draft control, as shown in FIG. 4, a region in which the flow rate changes in a quadratic curve is set between the dead zone setting region c and the point d at which the total amount starts to flow.
In the draft control, the draft control is performed by setting a curve that gradually inclines gently at the beginning so that the work implement rising output is output only when it greatly deviates from the target set value We are trying to stabilize.

The above-mentioned flow rate characteristics are stored in advance in the storage device of the control unit 18, and when the changeover switch 19 is operated to select one mode, the flow rate characteristics suitable for the mode are obtained. The rising solenoid valve 12 or the lowering solenoid valve 13 is energized and controlled according to a command from the control unit 18 while calculating the deviation between the selected value and the detected value.

[0013]

As described above, the present invention has the position control mode and the draft control mode, and controls the ascending solenoid valve and the descending solenoid valve in response to a command from the controller to control the hydraulic lifting mechanism. In a hydraulic control device for a tractor configured to rotate up and down, the position control mode is set to a flow rate characteristic in which the relationship between the deviation and the flow rate is substantially proportional, and the draft control mode is set to the deviation. Since the flow rate characteristic is set so that the flow rate changes in a quadratic function, the position control allows the working machine to operate in proportion to the operation amount of the position operation lever, so that the working machine can be accurately moved up and down. In the draft control, the plow greatly moves up and down only when a large load is applied, and does not react sensitively to a small load, so that the control can be stabilized.

Moreover, since the selection of these flow rate characteristics can be easily performed by the changeover operation of the changeover switch, the operability is improved.

[Brief description of drawings]

FIG. 1 is an overall side view.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a graph showing a flow rate characteristic of position control.

FIG. 4 is a graph showing a flow rate characteristic of draft control.

[Explanation of symbols]

 1 tractor 4 hydraulic cylinder case 6 lift arm 10 plow 12 solenoid valve for raising 13 solenoid valve for lowering 14 potentiometer 15 position lever 16 draft setting device 17 A / D converter 18 control unit

Claims (1)

[Claims] 1. A structure having a position control mode and a draft control mode, which controls an ascending solenoid valve and a descending solenoid valve in response to a command from a controller to vertically rotate a hydraulic lifting mechanism. In the hydraulic control device of the tractor, the position control mode is set to a flow rate characteristic in which the relationship between the deviation and the flow rate is substantially proportional, and in the draft control mode, the flow rate is a quadratic function with respect to the deviation. A hydraulic control device for a tractor, characterized in that the flow rate characteristic is changed to