JP2574432B2 - Hydraulic lifting and lowering control device of transfer agricultural machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulic lift control device for a mobile agricultural machine such as a tractor, and the like, in which the control dead zone width is automatically changed to enable optimal hydraulic lift control. Things.

[Prior art] Conventionally, in this type of mobile agricultural machine, the control dead zone width is:
In general, a system in which an operator switches and sets the sensitivity setting device as appropriate is generally used, and the switching is performed in accordance with soil conditions of a field or the like.

[Problems to be Solved by the Invention] In order to accurately position the ground work machine and increase the work accuracy, it is desirable that the dead zone width is narrow. However, when the dead zone width is narrow, while lifting the ground working machine, when the hydraulic oil leaks from the hydraulic cylinder constituting the hydraulic lifting mechanism and the ground working machine slightly descends, it is attempted to raise the ground working machine. As a result of the operation of the hydraulic pump, the operating pressure oil is fed into the hydraulic cylinder, and ascending and descending repeatedly, the engine horsepower is unnecessarily consumed, which may lead to a horsepower loss.

[Means for Solving the Problems] The present invention has been proposed in view of the above problems, and has taken the following technical means.

That is, a ground work machine is connected to the rear of the body via a hydraulic lifting mechanism so as to be able to move up and down freely, and the hydraulic lifting mechanism is controlled using a proportional solenoid valve. Has a control means for reducing the width of the control dead zone and providing control means for widening the width of the control dead zone when the ground working machine is lifted up.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a description will be given of the configuration. Reference numeral 8 denotes an agricultural tractor, and a rotary tilling device 3 is connected to a rear portion of the body of the agricultural tractor 8 via a three-point link mechanism 9 so as to be able to move up and down. The three-point link mechanism 9 includes a top link 14 and left and right lower links 15, and connects an intermediate portion of the lower link 15 and a lift arm 11 described later with a lift rod 16.

A hydraulic cylinder 2 comprising a cylinder 2a and a piston 2b is accommodated in a hydraulic cylinder case 10 at the rear of the body 1 of the agricultural tractor 8, and the lift arm 11 is pivotally mounted on the left and right outer sides of the hydraulic cylinder case 10. Supported.

The bell crank 11a provided at the base end of the lift arm 11 is connected to the connecting rod 12 on the hydraulic cylinder 2 side. When the piston 2b moves in the front-rear direction, the lift arm
11 is configured to rotate vertically.

The rotating base 13 of the one-sided lift arm 11 has a lift arm
A lift arm angle sensor 6 for detecting a rotation angle of 11 is attached.

Energize the rise control proportional solenoid valve 4 to release the hydraulic cylinder 2
When the operating oil pressure flows into the oil chamber 17 of the hydraulic cylinder 2, the lift arm 11 rotates upward, and conversely, the lowering control proportional solenoid valve 5 is excited to discharge the operating oil in the oil chamber 17 of the hydraulic cylinder 2. Then, the lift arm 11 is configured to descend by the own weight of the rotary tilling device 3.

20 is a constant current circuit for ascending, 21 is a constant current circuit for descending. These constant current circuits 20, 21 are interposed between the CPU 34 and the solenoid valves 4, 5, and are operated by a command from the CPU 34. The proportional solenoid valve 4 for ascending control or the proportional solenoid valve 5 for descending control is controlled.

In the vicinity of the driver's seat 23 above the rear wheel 22, a hydraulic operating lever 24 for setting the elevation height of the rotary tillage device 3 is provided.
A potentiometer is provided at the rotation base of the hydraulic operation lever 24.
24a is attached.

Until the set value of the potentiometer 24a and the detection value of the lift arm angle sensor 6 substantially match, an ascending command or descending command is output from the CPU 34 to the solenoid valves 4 and 5,
Here, position control is performed.

Reference numeral 25 denotes a tillage depth setting device provided near the driver's seat 23, and reference numeral 27 denotes a tillage depth sensor for detecting the swing angle of the rear cover 26. When the tillage depth setting device 25 is operated, the proportional solenoid valve 4 for raising control is set so that the set value and the detection value of the tillage depth sensor 27 substantially match.
Alternatively, the lowering proportional solenoid valve 5 is configured to be selectively excited, and the depth control is performed here.

Although not shown, the tractor can also perform draft control, and the draft control will be described below.

A drag setting device (not shown) is provided near the driver's seat 23. The drag setting device 25 is usually used as a substitute. Further, a draft sensor (not shown) for detecting a pressing force or a pulling force acting on the top link 14 is provided at a body side base of the top link 14, and a draft load detected by the draft sensor with respect to a set load of the drag setting device is provided. When the draft load is larger than the set value, a rising command is output from the CPU 34 to the constant current circuit 20 for raising, and when the draft load is smaller than the set value, a lower command is dropped from the CPU 34. It is provided to the constant current circuit 21 to lower a plow working machine (not shown).

Reference numeral 28 denotes a work mode switching panel, which can select any one of the above-described position control, depth control, and draft control by appropriately operating a changeover switch.

Reference numeral 7 denotes an upper limit setting device, which can raise the rotary tillage device 3 to the height set by the upper limit design device 7. More specifically, when the elevating switch 29 is pressed once, the rotary tilling device 3 rises to the height determined by the upper limit setting device 7, and when the elevating switch 29 is pressed again, the hydraulic operating lever is pressed.
It is configured to descend to the height set in 24.

In FIG. 2, the horizontal axis shows the displacement amount, which is the difference between the set value and the detected value, and the vertical axis shows the flow rate.

The operation will be described with reference to the same drawing. When the hydraulic operating lever 24 is operated upward at the end of the field and the rotary tilling device 3 is raised to the non-working position C near the upper limit position, the hydraulic operating lever 24 A target position is set by the provided potentiometer 24a.

Then, the larger the amount of displacement, which is the difference between the target position and the current position, the greater the flow rate of the working oil pressure flowing into the hydraulic cylinder 2, and the amount of displacement is gradually eliminated and the target position approaches. Come, hydraulic cylinder 2
The amount of working pressure oil flowing into the tank is reduced. Therefore, the movement of the lift arm 11 becomes slow. Then, when the displacement amount becomes a, it enters the dead zone width A, and the rotary tillage device 3 stops rising and holds this position.

When the rotation of the rotary tilling device 3 stops, the dead zone width is changed from A to B substantially at the same time, and the dead zone width is switched from the narrow dead zone width to the wide dead zone width.

Conventionally, the dead zone width is fixed to one type,
For example, in the above example, if the dead zone width is fixed at A and the control is continued as it is, the following problem occurs.

That is, while the rotary tilling apparatus 3 is stopped at the ascending position, the hydraulic oil leaks from the hydraulic cylinder 2 and the lift arm 11 descends beyond the dead zone width A, so that the output for immediately raising the hydraulic cylinder 2 is output. This is output from the CPU 34, and therefore, the rotary tilling apparatus 3 repeats unnecessary raising and lowering operations such as raising and lowering, which results in an increase in oil temperature.

However, in this embodiment, when the rotary tilling device 3 is raised to the vicinity of the upper limit position, the dead band width automatically changes from the narrow dead band width A to the wide dead band width B, so that the working pressure oil leaks from the hydraulic cylinder 2. However, the rotary tilling device 3 does not rise until the displacement amount becomes b, and the time until the output to be raised becomes longer. As a result, there is no increase in oil temperature and no loss in engine horsepower.

In particular, since the dead zone width B after the stop of the rotary tilling device 3 has been changed to a value larger than that during operation as shown in FIG. 2, when the rotary tilling device 3 descends greatly, the hydraulic cylinder 2 The initial flow rate of the hydraulic oil flowing into the inside increases, and the rotary tilling device 3 rises at a stretch. Therefore, due to the inertial force, the dead band width B enters the vicinity of the center position (point 0), and the time until the rising output is output again can be lengthened.

[Effects of the Invention] The present invention relates to an apparatus in which a ground working machine is connected to a rear portion of a machine body via a hydraulic lifting mechanism so as to be able to move up and down, and the hydraulic lifting mechanism is controlled using a proportional solenoid valve. When working, the control dead zone width is reduced,
Since the control means for widening the control dead zone width is provided when the ground working machine is lifted, high-precision control is possible when the ground working machine is in a working state, and
When the ground work machine is lifted, the time required for the output to increase again becomes longer even if the operating oil pressure leaks from the hydraulic cylinder that composes the hydraulic elevating mechanism. Problems such as increasing the temperature can be eliminated.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a control block diagram, FIG. 2 is a characteristic graph showing a relationship between a displacement amount and a flow rate, and FIG. 3 is an overall side view. DESCRIPTION OF SYMBOLS 1 ... Body 2 ... Hydraulic cylinder 3 ... Rotary tilling device 4 ... Proportional solenoid valve for ascending control 5 ... Proportional solenoid valve for descending control 7 ... Upper limiter 8 ... Agricultural tractor 9 ... 3-point link mechanism

Claims (1)

(57) [Claims] A ground work machine is connected to a rear portion of a machine body via a hydraulic lift mechanism so as to be able to move up and down, and the hydraulic lift mechanism is controlled using a proportional solenoid valve. , A control means for reducing the width of the control dead zone and increasing the width of the control dead zone when the ground working machine is lifted is provided.