JPS5826931B2 - Work equipment lifting mechanism for ground-based work equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ground-based working machine that is configured, for example, to have a rotary tilling device attached to the rear of a tractor and to perform tilling while traveling.

In the above-mentioned ground-based work equipment, pre-set Work load fluctuations are detected by the deviation between the engine rotation speed and the actual engine rotation speed,
It has been considered to control the raising and lowering of the tilling device based on this detection result.

At the same time, the system also detects the deviation between the actual height of the ground work equipment relative to the tractor and the arbitrarily set target height.
It has also been considered to increase the lifting speed when the deviation is large, and to reduce the lifting speed when the deviation is small, thereby accurately and quickly controlling the lifting to the target height.

However, according to the above-mentioned control, when there are locally hard parts or raised parts in the field, first, an increase in load is detected by detecting a decrease in engine speed, and then
The ground working device is raised and load reduction control is performed, and then the ground working device reaches near the end of the hard portion or raised portion, the load is relatively rapidly reduced, and descending control is performed. In this case, the deviation from the target height of the ground work equipment has become significantly larger due to the previous ascent control, resulting in a high-speed descent. If this high-speed descent continues for a long time, the load will increase rapidly and the engine speed will drop significantly. First, there is the problem that hunting occurs in a work area where there are repeated hard parts or raised parts as described above, making it difficult to perform stable control.

The present invention is intended to solve the above-mentioned problems and to perform stable elevation control.

Hereinafter, embodiments of the present invention will be described in detail based on illustrative drawings.

FIG. 1 shows a ground working machine in which a rotary tilling device 1 as a ground working device is attached to the rear of a tractor 2 so that it can be raised and lowered, and the rear propulsion wheels 4, 4 and the tilling device are powered by an engine 3 mounted on the tractor 2. 1 and also drives a hydraulic pump (not shown), and operates a hydraulic control valve (described later) which is appropriately switched and activated by an electric control signal. The cylinder 5 is expanded and contracted to cause a lift arm 6 connected to the cylinder 5 to swing up and down, thereby driving the tilling device 1 suspended and supported by the lift arm 6 up and down.

Based on the load fluctuation of the hydraulic cylinder 5 and the engine 3 and the relative height change of the tilling device 1 with respect to the tractor 2,
It is configured to be automatically controlled, and its details will be explained with reference to the block diagram in FIG. 2.

A signal E from the detector 7 that detects the actual rotational speed of the engine 3 and a signal A from the rotational speed setter 8 that sets the maximum engine rotational speed according to the accelerator setting are applied to the first subtractor 9. , the engine load is detected as the amount of decrease A-E in the engine rotational speed.

Further, a signal from the first subtractor 9 and a signal from the plowing depth setting device 10 for adjusting the relative level of the tilling device 1 with respect to the tractor and changing the target plowing depth are applied to the adder 11. , the signal from this adder 11 and the signal from a level detector 12 for detecting the relative level of the tilling device 1 with respect to the tractor 2 are applied to a second subtractor 13, which is connected to each of the detection and setting devices 7, 8, 10 and 12. Depending on the balance of the signals from the subtractor 12, a signal for determining whether to raise or lower the tilling device 1 is taken out from the second subtractor 13 in view of the change in engine load and the set plowing depth value.

The signals A-E from the first subtractor 9 increase as the engine speed decreases, and the signals H and L from the plowing depth setter 10 and level detector 12 increase as the plowing depth increases. If the tilling device 1 is located shallower than the set plowing depth position while the engine rotation speed is decreasing, the rotation speed decrease amount (engine load) A
-E > 0 and deviation amount H-L from the set tilling depth of tilling device 1
If < and 0 are equal, the output from the second subtractor 13 becomes zero, and it is determined that the tilling device 1 does not need to be raised or lowered. If the engine rotational speed reduction amount A-E increases from this state, the second
When the output from the subtractor 13 becomes positive and it is determined that the tilling device 1 needs to be raised, and conversely, when the engine rotational speed reduction amount A-E decreases, the output from the second subtractor 13 becomes positive. becomes negative, and it is determined that the tilling device 1 needs to be lowered.

Then, the raising and lowering of the tilling device 1 is controlled so that the above-mentioned balanced relationship is established based on the change in the amount of decrease in engine rotational speed and the change in the signal from the level detector 12 as the tilling device 1 is raised and lowered.

First, when the output from the second subtractor 13 is positive, the hydraulic cylinder 5
On the other hand, when the output is negative, the lowering valve 15 of the hydraulic cylinder 5 is opened so that the lift arm 6 and the tilling device 1 are lowered by their own weight.

Both valves 14 and 15 are controlled as follows based on the output from the second subtractor 13.

First, the output from the second subtractor 13 is input to three comparators 16, 17 and 18, and if the output is positive, the first comparator 16 determines this and the rising valve 14
The spreader 19 works, and the tilling device 1 is continuously raised at a constant speed.

Further, while the output is negative and the feed value is relatively small, the second comparator 17 operates, and accordingly, the intermittent signal generator 20 and the amplifier 21 of the descending valve 15 operate. , the tilling device 1 is intermittently lowered by its own weight.

Then, when the output is negative and the feed value increases, the third comparator 18 is activated, and accordingly, the amplification device 21 is continuously activated, and the tiller 1 is continuously activated by its own weight. It will be lowered.

(However, in this case, the second comparator 17 is also activated and an intermittent lowering control signal is output, but continuous lowering control has priority.

) Moreover, even if the engine rotational speed is greatly reduced, the above-mentioned balanced relationship is established and stability is maintained in a low-speed running state or a high-load state by only controlling the elevation discrimination by pressing the button on the second subtractor 13. As a result, there is a risk of a decrease in work efficiency or engine stoppage, so this problem is solved by the following control.

In the past, the signal from the first subtractor 9 is applied to three comparators 22, 23 and 24 whose inputs are respectively set to different reference values a, b, and c, where a < b < c. , due to an increase in the engine load, the engine speed decreases and the signal from the first subtractor 9 increases 7, exceeding the first reference value a given by the setter 25 and the signal given by the setter 26. When the value becomes smaller than the second reference value, the fourth comparator 22 is activated and a signal is issued to stop the operation of the third comparator 18, and the negative output from the second damper 13 is output. Even if the third comparator 18 is operated in a state where the third comparator 18 is operated, the lowering valve 15 is intermittently controlled by the operation of only the second comparator 17 while the fourth comparator 22 is operated.

Furthermore, when the engine speed decreases and the signal from the first subtractor 9 exceeds the second reference value C and becomes smaller than the third reference value C given by the setter 27, the signal from the fifth comparator 23
is activated, a descending prohibition command signal is input to the amplifier 21 of the descending valve 15, and even if there is a descending command from the second subtractor 13, the descending operation is prohibited (1), and the engine rotational speed is further reduced. Accordingly, when the signal from the first subtractor 9 exceeds the third reference value C, the sixth comparator 24 is activated to issue a forced rise command signal, and based on this signal, the intermittent signal generator 28 is activated, and the lifting valve 14 is operated intermittently regardless of the lifting control command from the second subtractor 13.

As a result, in a range where the amount of decrease in engine speed is smaller than the first reference value a, the tilling device 1 is controlled to rise and fall based on the command from the second subtractor 13, and the first reference value a and the second reference value a are In the range between the reference values, intermittent descending control is performed even if there is a continuous descending command from the second subtractor 13, and
In the range between the reference value and the third reference value C, the second subtractor 13
The tilling device 1 is raised only when there is a command to raise it, and lowering is prohibited.Furthermore, if the value exceeds the third reference value C, the tilling device 1 is forcibly raised to lower the load below the second reference value C. This will help reduce the amount of damage.

With the above-described structure, the following control is performed when there is a localized hard part or the like during work and the load increases significantly.

First, the tilling device 1 is controlled to ascend based on the detection of a decrease in engine rotational speed (increase in load), and then, when an increase in engine rotational speed (load reduction) is detected, the tillage device 1 is controlled to descend. In this case, the tillage device 1 has deviated significantly upward from the set target height and the detector 12
Therefore, the output from the second subtractor 13 also becomes a large negative value, and the operating range of the third comparator 18 (
(connected descent).

Furthermore, at the beginning of the descent, the engine rotational speed is sufficiently high, so the output of the first subtractor 9 is also smaller than the first reference value a, and therefore,
The descending control is continuous descending, and the tilling device 1 descends at high speed.

Then, as the load decreases, the load increases slightly and the fourth comparator 2
2 is activated, the third comparator 18 is deactivated even if the tilling device 1 is still far from the target height and the command from the second subtractor 13 is for continuous descent. Second
Intermittent lowering control is performed by operating only the comparator 17, and a sudden increase in load due to rapid lowering is avoided.

When the hard part is reached during this low-speed descent, the above control is repeated again.

As described above in detail in the embodiments, according to the present invention, when the ground work device 1 deviates significantly upward from the target height, it descends quickly, and when it approaches the target height, it descends at a low speed. Although it is possible to control the transition to the target height quickly and accurately, when the engine load increases, low-speed descending control is given priority over the transition control to the target height to prevent sudden descent due to rapid descent. Prevents an increase in load, and prevents the ground work device 7 from being large and rapidly controlled to raise and lower during work where bumps or hard parts that cause a local increase in load appear repeatedly, causing nchching. Now you can.

[Brief explanation of drawings]

The drawings illustrate an embodiment of the working device elevating mechanism for a ground-based working machine according to the present invention, and FIG. 1 is an overall side view of the riding power cultivator;
FIG. 2 is a block diagram of the control mechanism. 1...Ground work equipment.

Claims (1)

[Claims] 1 In a ground work machine equipped with a control mechanism that automatically raises and lowers the ground work device 1 attached to the machine body based on the engine load detection result, the actual height of the ground work device 10 relative to the machine body and the set target height A mechanism is provided to detect a deviation from the ground working device 1, and the structure is configured to increase the descending speed of the ground work device 1 when the deviation is large, and to reduce the descending speed when the deviation is small, and in a light load region where the engine load is constant. , increase the lowering speed of the ground work equipment,
The ground work device is equipped with a descending speed limiting mechanism that reduces the descending speed even when the ground working device 1 is in a rapid descending control state based on the increase in height deviation when the engine load increases from the above range. Work equipment lifting mechanism.