JPH0716325B2 - Tractor work implement lift control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a deceleration mode in which the descending speed is gradually decelerated in order to avoid a sudden collision at the time of landing when a working machine mounted on a tractor descends. is there.

(B) Conventional technology When lowering a work machine that has been conventionally mounted on a tractor,
It is well known that the pulse signal is changed in accordance with the lowered position of the lift arm to change the descending speed. For example, it is like the technique described in JP-A-61-293305. Further, a technique for changing the speed in order to eliminate the impact when the working machine touches down is also known. For example, it is as in Japanese Patent Publication No. 61-34766.

(C) Problems to be Solved by the Invention In the present invention, the slow-down of the solenoid valve is kept constant for the ON time of the pulse drive, and the OFF time is changed to form the deceleration mode. This solves the problem that when the amount of discharged oil changes due to fluctuations in engine speed, changes in oil temperature, and the like, which occurs when the time is changed, the descending speed changes accordingly.

That is, the ON time is set to a time in which the lift arm 4 changes by a constant rotation angle, and by setting this to a constant time,
Since the deceleration is set depending on the length of the OFF time, even if there is a change in the discharge oil amount, the descending speed does not change, and it is possible to obtain a constant slow descending.

(D) Means for Solving the Problems The object of the present invention is as described above, and a configuration for achieving the object will be described below.

In the configuration in which the tractor descends the lift arm 4 after the end of field travel, the pressure oil of the hydraulic cylinder that raises and lowers the lift arm 4 is controlled by an electromagnetic valve, and the electromagnetic valve is configured to intermittently open and close by a pulse signal, The pulse signal is changed according to the lowered position of the lift arm, and the OFF time of the pulse signal is divided into a plurality of stages from the highest position to the lowest position of the angle of the lift arm 4, and the closer it is to the lowest position. The ON time of the pulse signal is set according to the time during which the lift arm 4 changes by a fixed minute angle α in the lift angle.

(E) Embodiments and Functions The object and structure of the present invention are as described above. Next, the structures and operations of the embodiments shown in the accompanying drawings will be described.

FIG. 1 is a side view of a state in which a rotary cultivator is mounted on a tractor, FIG. 2 is a side view showing a lowered state of the rotary cultivator of the present invention, and FIG. 3 is a rotation angle of a lift arm 4 and an electromagnetic valve. FIG. 4 is a drawing showing the relationship with the OFF time, FIG. 4 is a drawing showing the OFF time control in pulse driving, and FIG. 5 is a side view showing the problems associated with a sudden fall.

The configuration of the rotary tiller attached to the tractor will be described with reference to FIG.

The outer circumference of the rotation path of the tiller claw 1 is covered with a tiller cover 5, and the rear cover 2 is pivotally supported at the rear portion of the tiller cover 5. The rear cover 2 also serves as a sensor for automatic reverse control, and the rotation of the rear cover 2 is transmitted to the rotary encoder in the control box by the feedback wire 3 to change it to an electrical value. The signal is transmitted as a pulse signal for controlling the electromagnetic valve to switch the electromagnetic valve.

In the rotary tiller with this configuration, the tiller cover 5 can be adjusted back and forth, and the tiller cover adjusting handle 16 is used to adjust the tiller cover 5 forward and backward.

When the tillage cover 5 is adjusted back and forth, the rear cover 2 is also adjusted back and forth. 17 is a depth wheel adjustment handle.

As described above, the present invention is thus attached to the working machine mounting device of the tractor, and when being lifted and lowered by the lift arm 4, the rotary tilling device is fully raised for the field end traveling, and after the traveling, the tilling posture is resumed. This is related to slow descent when lowering the rotary cultivator in order to return to.

FIG. 2 and FIG. 5 show the situation in which the tractor restarts the tilling work after traveling at the end of the field.

When the slow descending device at the time of grounding is not provided, as shown in FIG. 5, the tilling claw 1 is moved to the ground surface L by the inertial force of the rapid descending.
It bites deeply from the ground, and the biting amount h increases. The portion with the large bite amount h is concentrated on the headland portion, and the headland is deeply engraved.

Further, even if the slow descending device at the time of grounding is provided, if the speed at the slow descending becomes too slow, the fitting distance l shown in FIG.
It becomes too long, and uncultivated land is created on the headland.

According to the present invention, the biting amount h is made close to 0 and the fitting distance 1 is made as short as possible.

In the present invention, even when the electromagnetic valve that operates the lift arm 4 is opened, the oil is sent by intermittently opening and closing by the pulse signal.

The driving configuration for intermittent opening / closing by the pulse signal is set as shown in FIG.

That is, the ON time t0 for exciting the solenoid of the electromagnetic valve to open the oil passage is constant, and the constant time is, as shown in FIG. 4, the time during which the lift arm 4 changes by 2 degrees in the lift angle. The ON time for exciting the solenoid is fixed.

In order to gradually decrease the descending speed as the lift arm 4 descends, the ON time of the solenoid is the same. Therefore, the OFF time of the solenoid t1 · t
The length of 2 is changed.

That is, as shown in FIG. 3, the OFF times t1 and t2 of the solenoid are divided into five stages from the angle of the lift arm 4 from 0 degrees at the highest position to 70 degrees at the lowest position. It is configured to change to 5 steps up to 40 mm seconds.

Therefore, as the lift arm 4 descends, the pulse signal turns off.
Since the time changes as shown in FIG. 3, the descending speed of the rotary tiller also gradually decreases as shown in the graph of FIG. As a result, the speed at the time of landing on the ground surface L slows down to almost zero, and the automatic plowing depth control is started.

At the end of the field, the rotary tiller is raised to the highest position by rotating the position operation lever to the highest position while keeping the automatic control of the plowing depth.

When the operator operates the position control lever to the lowest position or below the setting position of automatic plowing depth control after the completion of traveling, the slow descent is performed only until it falls within the range of automatic plowing depth control. To be seen. Then, when the operator enters the area of the automatic plowing depth control, the tilling work is continued in the automatic plowing depth automatic control state that was performed before reaching the end of the field.

As shown in the hydraulic circuit diagram of FIG. 8, the lowering check valve 7 is an interlocking rod 10 of FIG. 10 in order to be opened in the mechanical hydraulic valve V when the switching spool 6 is closed at the time of lowering.
The lowering check valve 7 is opened by being pushed by the push rod 11.

Since the lowering check valve 7 has not been conventionally assigned the purpose of slowly descending, as shown in FIG. 11 and FIG.
It was constructed like a short poppet valve, and the poppet valve had only two uses: open or closed.

In this configuration, the lowering check valve 7 is not a check valve that only opens and closes, but a throttle taper portion 7a is provided in addition to the closing poppet valve portion 7b.

With this configuration, when the lowering check valve 7 is not fully retracted and is retracted and opened by the distance m in FIG. 10, the return oil for descending from the hydraulic cylinder S is given a throttle action. Of.

The lowering check valve 7 is closed when the lift arm 4 is set to the highest position for the field end traveling, and when lowering after the completion of the traveling, the operator sets the hydraulic operation lever 9 to the lowest position. However, as the lift arm 4 descends, the switching spool 6 and the lowering check valve 7 are gradually and integrally pushed back to the neutral side by the operation of the feedback mechanism.

When the lowering check valve 7 is returned by the feedback mechanism, until the lowering check valve 7 is completely closed,
The tapered portion 7a for diaphragm is provided so that the diaphragm effect is gradually exhibited.

Further, as shown in FIG. 7, if the stopper 8 is made detachable by projecting the stopper 8 in the turning locus of the hydraulic operation lever 9, when the stopper 8 is provided, the hydraulic operation lever 9 is at the lowest position. Distance m in Fig. 10 without turning to 9 '
It is possible to stop at the position, and in this state, the descent can be started while the diaphragm effect of the diaphragm taper portion 7a is exerted.

Further, if the stopper 8 is removed, the check valve 7 can be retracted to the position of the distance n in FIG. 10, and at this position, the throttling effect of the throttling taper portion 7a is not initially exerted, so it is suddenly increased halfway. When the feedback check mechanism gradually pushes back the lowering check valve 7 and the tapered taper portion 7a begins to be fitted into the spool hole, the throttle effect gradually begins to be exerted.

With this configuration, it is possible to gradually and slowly descend rather than stepwise as shown in FIG.

(F) Effects of the Invention Since the present invention is configured as described above, it has the following effects.

With the solenoid valve slowly descending, the ON time of pulse drive is constant,
Since the deceleration mode is configured by changing the OFF time, if the ON time is changed as in the past, if the discharge oil amount changes due to engine speed fluctuations, oil temperature changes, etc. The speed was changing accordingly, but ON
The time is set to a time in which the lift arm 4 changes by a fixed rotation angle, and by setting this to a fixed time, the deceleration is OF
Since it is set depending on the length of F time, even if there is a change in the discharge oil amount, the descending speed will not change,
It is possible to obtain a constant slow descent.

[Brief description of drawings]

FIG. 1 is a side view of a state in which a rotary cultivator is mounted on a tractor, FIG. 2 is a side view showing a lowered state of the rotary cultivator of the present invention, and FIG. 3 is a rotation angle of a lift arm 4 and an electromagnetic valve. Drawing showing the relationship with OFF time, Fig. 4 is a drawing showing OFF time control in pulse drive, Fig. 5 is a side view showing a problem associated with sudden lowering, and Fig. 6 is a mechanical hydraulic valve for slow lowering. A speed curve in the case of being configured by the shape of the lowering check valve 7 provided on the V, FIG. 7 is a side view showing the relationship between the hydraulic operating lever 9 and the lift arm 4, and FIG. 8 is a hydraulic circuit diagram of the configuration. FIG. 10 is a cross-sectional view of the hydraulic valve V having the structure, and FIG. 10 is a drawing showing the structure of the lowering check valve 7.
11 and 12 are cross-sectional views of conventional lowering check valves 27 and 37. 1 ... Tilling claw 4 ... Lift arm l ... Fitting distance h ... Biting amount

Claims (1)

[Claims] 1. A structure in which a tractor descends a lift arm 4 after the end of field travel has been completed, and pressure oil of a hydraulic cylinder for raising and lowering the lift arm 4 is controlled by an electromagnetic valve,
The electromagnetic valve is configured to be intermittently opened and closed by a pulse signal, the pulse signal is changed according to the lowered position of the lift arm, and the OFF time of the pulse signal is the lift arm 4 from the highest position to the lowest position. Is divided into multiple steps, and the time is set to gradually increase for each step as it approaches the lowest position, and the ON time of the pulse signal is
A work implement lift control device for a tractor, wherein the lift arm 4 is set according to a time for which the lift angle changes by a fixed minute angle α.