JPH0787724B2 - Work implement lift control device for tractor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a work implement lift control device for a tractor.

[Problems to be Solved by Prior Art and Invention]

In recent years, a hydraulic control mechanism that raises and lowers a working machine has been made possible by electronic control, but the characteristic of this electronic control device is that the operation of the hydraulic valve can be finely controlled.
Therefore, the width of the dead zone can be made narrower than that of the mechanical hydraulic control device, and the work machine lifting control can be finely performed. However, while fine control is possible, there are the following problems. That is, if the lift arm is lifted and stopped in a state where the working machine is raised to the air, the working oil in the hydraulic cylinder leaks due to the weight of the lifted working machine, and the lift arm fluctuates downward. Even if the downward movement of the lift arm is slight, the width of the control dead zone is narrow, so that the angle of the lift arm deviates from the control dead zone, and the lift arm lift output is produced. Then, the descending and ascending operations of the lift arm are continuously repeated, which results in a so-called jumping phenomenon, and as a result, the oil temperature in the hydraulic mechanism rises.

[Means for Solving the Problems]

The present invention has been proposed in view of the above-mentioned problems, and has taken the following technical means.

That is, a lift arm angle sensor that detects the angle of a lift arm that raises and lowers a work machine, a position setter that sets the angle of the lift arm, and a hydraulic mechanism that raises and lowers the lift arm are provided to set the position. In the working machine lifting control device of the tractor configured to operate the hydraulic mechanism to control the lifting of the working machine so that the detection value of the lift arm angle sensor matches the set value set by the lifter, The dead band width increases when the lift arm starts moving, the dead band width decreases when the lift arm starts to move, and the dead band width when the lift arm is stopped is the dead band width when the lift arm moves downward. A work implement lift control for a tractor, characterized in that a control means is provided so that the dead zone width is wider than the dead zone width on the side with respect to upward movement of the lift arm. The configuration of the apparatus.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. First, the structure will be described. A rotary tiller 1 serving as a working machine is connected to the rear part of the body of the tractor 11.
Reference numeral 7 denotes a tilling claw attached to the tilling shaft 8. Also,
Reference numerals 9 and 10 are a top link and a lower link that form a three-point link mechanism. Front and rear wheels 12 and 13 are provided at the front and rear of the tractor 11, and the power of an engine (not shown) housed in the bonnet 14 is appropriately decelerated via a transmission mechanism in the transmission case 17 to reduce the rotational power. Is transmitted to the front wheel 12 and the rear wheel 13.

A lift arm 2 for raising and lowering the working machine is rotatably supported on both left and right sides of a pressing cylinder case 19, and the lift arm 2 and the lower link 10 are connected by a lift rod 21. In this embodiment, the lift rod 21 on one side is composed of a stretchable pressing cylinder, but it may be a normal rod type that is not stretchable.

Further, a PTO shaft 22 is projectingly mounted on the lower rear part of the body of the tractor 11, and a rotary tiller 1 is mounted on the PTO shaft 22 via a universal joint shaft 23.
The rotational power is transmitted to the side.

The position setter 3 for setting the lifting position of the lift arm 2 is
It is attached to a rotating base of a hydraulic operation lever 24 provided on the side of the cockpit 16.

When the hydraulic operating lever 24 is operated back and forth, the position setter 3 is rotated, and the value of the lift arm angle sensor 4 attached to the rotary shaft 20 of the lift arm 2 is adjusted to the height set by the position setter 3. The hydraulic mechanism is rotated up and down to match.

Reference numeral 5 in FIG. 2 shows the entire hydraulic lifting control device, and the position setter 3 and the lift arm angle sensor 4 are connected to the A /
It is connected to the CPU 25 via the D converter 26. 27 is a drive unit connected to the output side of the CPU 25, and 28 is a proportional solenoid valve. The proportional solenoid valve 28 is controlled by an ascending side proportional solenoid 29 and a descending side proportional solenoid 30.
31 is an oil tank, 32 is a hydraulic pump, 33 is a check valve,
34 is an oil passage. When an electric current is applied to the ascending side proportional solenoid 29, the hydraulic oil sent from the hydraulic pump 32 flows into the hydraulic cylinder 18 through the check valve 3, and conversely when an electric current is applied to the descending side proportional solenoid 30. The valve 28 is switched to the descending side so that the hydraulic oil in the hydraulic cylinder 18 is discharged to the oil tank 31.

FIG. 3 shows the relationship between the lift arm 2 and the control dead zone, and FIG. 4 explains the contents of the control program.

In FIG. 3, reference numeral a indicates a target position of the lift arm 2. Before the lift arm 2 stops,
The dead zones having the widths indicated by reference signs c and d are set, and after the lift arm 2 is stopped, the dead zones of b upward and a downward are set. The dead zones b and a after the stop are larger than the dead zones c and d before the stop.

The operation will be described with reference to the flowchart of FIG.
When the detection value of the lift arm angle sensor 4 is R, the setting value of the position setter 3 is P, and the deviation thereof is X, X = R−P. First, the value R of the lift arm angle and the value P of the position setter 3 are read in step, and the deviation is calculated in step.

When the deviation exceeds a, a command for raising the lift arm 2 is issued (step), and at the same time, the detected value (R) of the lift arm angle and the set value (P) are read (step). Then, in step, it is judged whether or not the deviation X is within the narrow dead zone d, and if it is within the dead zone d, the ascending output is stopped, and if not, the step is repeated.

On the other hand, when the deviation exceeds b, a lowering output is issued to lower the lift arm 2 and step), the detected value (R) of the lift arm angle and the set value (P) are read (step), and the deviation X It is determined whether or not is within c.

If the deviation X is within the narrow dead zone, the lowering output is stopped, and if not, the steps are repeated.

Describing the operation with reference to FIG. 3, when the lift arm 2 is stopped at the target position a, the dead zone width (b) is c +.
In contrast to d, the dead zone width (b ') after being stopped at the set position is expanded to a + b. That is, when the lift arm 2 stops, (b) <(b '), and in particular, in this embodiment, a wide dead band is provided for the downward movement of the lift arm 2.

Therefore, even if the hydraulic oil leaks from the hydraulic cylinder 18 and the lift arm 2 gradually descends, it takes a long time to control the lift arm 2 to rise due to the wide dead zone. FIGS. 5 and 6 show the relationship between the pressure P of the hydraulic circuit and the time T. FIG. 5 shows the case of the conventional device and FIG. 6 shows the case of the present application.

In the conventional case, as shown in FIG. 5 (d), a jumping phenomenon in which ascending and descending are frequently repeated in a short time has occurred, but in the case of the present application, the lift arm 2 starts to descend and an ascending command is issued. Since the time interval (c) until the occurrence of is relatively long, such a jumping phenomenon does not occur, and therefore the inconvenience of increasing the temperature is also eliminated.

[Operation and effect of the invention]

The present invention is provided with a lift arm angle sensor that detects an angle of a lift arm that raises and lowers a work machine, a position setter that sets an angle of the lift arm, and a hydraulic mechanism that rotates the lift arm up and down. In the working machine lift control device for a tractor, which is configured to operate the hydraulic mechanism so as to lift and lower the work machine so that the detection value of the lift arm angle sensor matches the set value set by the position setter, When the arm is stopped, the dead band width becomes wider, when the lift arm starts moving, the dead band width becomes narrower, and the dead band width when the lift arm is stopped against the downward movement of the lift arm. A working machine for a tractor, which is provided with a control means for making the dead zone width on the side wider than the dead zone width on the side with respect to upward movement of the lift arm. Since it is a descending control device, when the lift arm is raised and the work machine is stopped in the state of being raised in the air, even if it slightly descends due to leakage of hydraulic oil, an ascending output is not output. As a result, the working machine does not frequently fall and rise to raise the oil temperature, and the working machine can be quickly lowered when it is lowered from the raised state. Is also good.

[Brief description of drawings]

The drawings show one of the embodiments of the present invention. FIG. 1: Overall side view. FIG. 2: Control circuit diagram. FIG. 3: Operation explanatory view. FIG. 4: Control flowchart. FIG. 5: A graph explaining the relationship between the pressure in the hydraulic cylinder and time. FIG. 6: Graph explaining the relationship between the pressure in the hydraulic cylinder and time. Explanation of code 1: Rotary tiller (working machine) 2: Lift arm 3: Positioner 4: Lift arm angle sensor 5: Hydraulic lift control device 11: Tractor

Claims (1)

[Claims] 1. A lift arm angle sensor for detecting an angle of a lift arm for raising and lowering a work machine, a position setter for setting an angle of the lift arm, and a hydraulic mechanism for raising and lowering the lift arm. A working machine lifting control device for a tractor configured to operate the hydraulic mechanism so as to lift and lower the working machine so that a detection value of the lift arm angle sensor matches a set value set by the position setter, When the lift arm is stopped, the dead band width is widened, when the lift arm starts moving, the dead band width is narrowed, and when the lift arm is stopped, the dead band width fluctuates downward due to the dead band width. The tractor working machine is provided with control means for making the dead zone width on the side of the lift arm wider than the dead zone width on the side of upward movement of the lift arm. Descending control device.