JP2731682B2 - Work vehicle ground work equipment lifting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a ground-type working device (such as a seedling planting device or a rotary tilling device), such as a riding type rice transplanter or agricultural tractor, which is connected to a machine body by a hydraulic cylinder so as to be able to move up and down freely. And a lifting / lowering structure for a ground working device of a working vehicle.

[0002]

2. Description of the Related Art As an example of the work vehicle described above, there is a riding type rice transplanter in which a seedling planting device (corresponding to a ground working device) is connected to the rear of the body so as to be able to move up and down. An example of the lifting structure is disclosed in Japanese Patent Application Laid-Open No. 3-119909. In this structure, a grounding float (6 in FIG. 1 of the above publication) (corresponding to a height sensor) for detecting the height from the rice field (corresponding to the ground) to the seedling planting apparatus is provided.
The ground float and the spool of the control valve for the hydraulic cylinder (9a in FIG. 1 of the above publication) are linked by a wire (14 in FIG. 1 of the above publication) (corresponding to linking means). As a result, as the detected value of the ground float deviates greatly from the set value to the descending side or the ascending side, the spool of the control valve is largely operated to the ascending side or the descending side, and the amount of oil supply / discharge to the hydraulic cylinder increases, With this hydraulic cylinder, the seedling planting device is quickly moved up and down, so that the seedling planting device is maintained at the set height from the rice field, and the seedling planting depth is kept constant.

[0003]

In the structure described above,
It is one spring (15 in FIG. 1 of the above-mentioned publication) that gives resistance to the upward movement of the ground float and the spool of the control valve. It increases linearly from the position. The resistance value of the above-mentioned spring is often set to a weak value so that the landing float smoothly follows the unevenness of the rice field so that the seedling planting device can be quickly moved up and down.

[0004] Therefore, for example, it is assumed that the front wheel of the airframe rides on the convex portion of the cultivator and the seedling planting device suddenly descends greatly. In this case, since the resistance value of the above-mentioned spring is weak, the ground float rises greatly, the spool of the control valve is largely operated to the rising side, and a large flow of hydraulic oil is supplied / discharged to the hydraulic cylinder, so that seedlings are planted. The device is quickly raised to the set height. However, if the operation of supplying and discharging a large flow of hydraulic oil to and from the hydraulic cylinder and quickly raising the seedling planting device is repeated, the seedling planting device will pass without stopping at the set height. Then, a state occurs in which the seedling planting device is lowered and then raised again, which may cause a hunting phenomenon. The present invention suppresses the hunting phenomenon of the ground working device while allowing the ground working device to perform a quick ascending and descending operation (especially ascending side) when the spool of the control valve for the hydraulic cylinder is near the neutral position. The purpose is.

[0005]

The feature of the present invention resides in the following structure of the above-described structure for lifting and lowering the ground working device of the working vehicle. In other words, a hydraulic cylinder for raising and lowering the ground working device with respect to the aircraft, a control valve for supplying and discharging hydraulic oil to and from the hydraulic cylinder, and a height sensor for detecting the height from the ground to the ground working device, As the detected value of the height sensor deviates greatly from the set value to the descending side or the ascending side, the spool of the control valve is largely operated to the ascending side or the descending side of the ground work device, and the amount of oil supply / discharge to the hydraulic cylinder is increased. The hydraulic cylinder is provided with a linking means for linking a height sensor and a spool of a control valve so that the hydraulic cylinder can be quickly extended and retracted, and the ground working device is configured to be maintained at a set height from the ground, If the spool of the control valve is located between the neutral position and the set stroke position on the ascending side, a small resistance is given to the movement of the spool to the ascending side, and the spool exceeds the set stroke position. When located raised side Te, it is provided with resistance adding means for providing a greater resistance to movement in the ascending side of the spool.

[0006]

According to the structure of the present invention, for example, as shown by a solid line in FIG. 6, the ground working device is slightly lowered with respect to the set height, and the spool 12 of the control valve is moved to the neutral position and the set stroke position A on the ascending side. When the operation is performed between the above-mentioned positions, a small resistance is given to the upward movement of the spool 12. Accordingly, in this state, the spool 12 is quickly moved upward with the lowering of the ground working device, but the opening degree is small. As a result, the hydraulic cylinder starts to extend quickly with the lowering of the ground work device and starts the raising operation of the ground work device, but the extension speed is slow. As a result, the ground operation device is smoothly lifted while quickly following the change in the unevenness of the ground.

Conversely, when the ground working device descends significantly with respect to the set height and the spool 12 of the control valve is moved upward (to the right in the drawing) beyond the set stroke position A,
Large resistance is given to the movement of the spool 12 to the rising side. Accordingly, in this state, the spool 12 is slowly moved upward with the lowering of the ground working device, but the opening degree is large. As a result, the hydraulic cylinder starts to elongate slowly with the lowering of the ground work device and starts the ascent operation of the ground work device, but the elongation speed is fast. In this way, if the lifting operation of the ground working device tends to be delayed, the ground working device may return to the set height before the lifting operation of the ground working device is started. Since the frequency of a large ascending operation at a high speed is reduced, it is possible to suppress a hunting phenomenon caused by elevating the ground working apparatus at a high speed and passing a set height.

[0008]

As described above, in the state where the vertical displacement of the ground working device with respect to the set height is small, the hunting phenomenon of the ground working device is performed while the quick lifting operation (especially ascending side) of the ground working device is performed. This makes it possible to perform an accurate and smooth ascending and descending operation of the ground working device, thereby improving the ground working accuracy (such as the planting depth accuracy of the seedling planting device).

[0009]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a seedling planting device 3 (corresponding to a ground working device) is provided at the rear of the body supported by the front wheel 1 and the rear wheel 2.
Are linked via a link mechanism 4 and a single-acting hydraulic cylinder 5 so as to be able to move up and down freely, to constitute a riding type rice transplanter which is an example of a work vehicle. As shown in FIG.
The planting arm 7 is rotatably supported at the rear of the planting mission case 6, and the seedling rest 8 is supported so as to be reciprocally traversable to the left and right with respect to the planting mission case 6. With the rotation of the arm 7, the seedlings are taken out from the seedling placing stand 8 and planted on the rice field surface G (corresponding to the ground).

As shown in FIGS. 2, 3, and 4, the hydraulic oil from the pump 10 is supplied to the pump port 20 of the case 15 and the control valve 1
1 (the spool 12 of the control valve 11 is in the neutral position), the cylinder port 22, the check valve 23, the oil passage 24, and the shutoff valve 25
, And is supplied to the hydraulic cylinder 5. Case 1
5, an operation shaft 26 is rotatably supported.
5, an operation arm 26a fixed to the operation shaft 26
Is in contact with one end of the spool 12 of the control valve 11.
A balance arm 27 and an arm 28 are fixed to the operation shaft 26 outside the case 15. As shown in FIGS. 2 and 1, a ground float 9 (corresponding to a height sensor) is disposed at the center of the right and left sides of the seedling planting device 3, and swings up and down around the horizontal axis P1 of the planting mission case 6. The rear part of the ground float 9 is freely supported. Then, one end of the balance arm 27 on the case 15 side and the ground float 9 are interlocked and connected via the balance arm 13 on the seedling planting apparatus 3 side and the inner wire 14a of the release wire 14 (corresponding to linking means). .

In the state shown in FIGS. 2, 3 and 5, the check valve 23 is operated by the rotary portion 29, the cam ball 30, and the operation spool 31 by operating a lifting lever 21 to be described later to the planting position.
Is being opened, and the shut-off valve 25 is also being opened. In the state shown in FIGS. 2, 3, and 5, when the seedling planting device 3 descends below the set height with respect to the ground float 9 that follows the ground surface G, the inner 14 a is pulled toward the ground float 9, The balance arm 27 and the operation arm 26a swing clockwise in FIG.
The first spool 12 is slid from the neutral position shown in FIG. 3 to the right in the drawing. Thereby, the first land portion 12a side of the pump 10 side in the spool 12 is opened, and the hydraulic oil from the pump 10 is supplied to the hydraulic cylinder 5 through the cylinder port 22 and the check valve 23, and the hydraulic cylinder 5 is extended. The seedling planting device 3 is raised.

Conversely, the seedling planting device 3
Rises above the set height, the inner 14a is returned to the balance arm 27 side, and the balance arm 27 and the operation arm 26a swing counterclockwise by the urging force of the spring 32. Control valve 1 by the urging force of
The first spool 12 is slid to the left from the neutral position shown in FIG. Thereby, the second land portion 12b side of the drain portion 18 side of the spool 12 is opened, and the hydraulic oil of the hydraulic cylinder 5 flows in the opposite direction to the above and the drain port 1
Then, the hydraulic cylinder 5 is contracted and the seedling planting device 3 is lowered. As described above,
When the seedling placement device 3 moves up and down with respect to the ground float 9 that follows the ground, the spool 12 of the control valve 11 is accordingly moved.
Is operated, the hydraulic cylinder 5 is extended and retracted, the seedling planting device 3 is maintained at the set height from the rice field G, and the planting depth of the seedlings is kept constant.

As shown in FIGS. 2 and 4, a rotary portion 29 is rotatably supported around a horizontal axis P2 of the case 15, and a first arm 33 and a second arm 34 are fixed to the rotary portion 29. ing. The lift lever 21 is supported by the first arm 33, and the pin 34 a of the second arm 34 contacts the arm 27 a of the balance arm 27 at the neutral position of the lift lever 21 to lower the balance arm 27 and the spool 12. Side (left side in FIG. 3) is prevented, and the second arm 34 moves the balance arm 27 and the spool 12 to the rising side (right side in FIG. 3) when the lifting lever 21 is in the raised position. It is a forced operation. With the above structure,
The raising / lowering lever 21 is placed at a planting position (a state where the seedling planting device 3 is planted and the above-described automatic raising / lowering operation of the seedling planting device 3 is performed), and a lowering position (the seedling planting device 3 is planted). The seedling operation is stopped, the lowering operation of the seedling planting device 3 is performed), the neutral position (the seedling planting device 3 stops the planting operation, and the seedling planting device 3 is stopped).
(A state in which the raising / lowering operation of the seedling is stopped), and an ascending position (a state in which the seedling planting device 3 stops the planting operation and the raising operation of the seedling planting device 3 is performed).

In this case, as shown in FIG.
9, a first recess 29a and a second recess 29b are provided, and a ball detent mechanism 35 is provided on the case 15 side. As a result, as shown in FIG.
When 1 is operated to the neutral position, the ball detent mechanism 3
5 enters the first concave portion 29a of the rotary portion 29, the elevating lever 21 is held at the neutral position, and the case 1
The cam ball 30 on the fifth side enters the second concave portion 29b,
The check valve 23 is closed. Therefore, the hydraulic oil from the hydraulic cylinder 5 is not stopped by the check valve 23, and the seedling planting device 3 does not descend. And the lifting lever 2
1 is operated to the ascending, descending and planting positions, as shown in FIG. 5 (the state of FIG. 5 is a state in which the elevating lever 21 is operated to the planting position), the cam ball 30 and the operation spool 31 are rotated by the rotary unit 29. The check valve 23 is opened by being pushed rightward on the paper. Thereby, the cylinder port 22
And the operation of supplying and discharging the hydraulic oil to and from the hydraulic cylinder 5 through the check valve 23 can be performed, and the raising and lowering operation of the seedling planting apparatus 3 is performed. When the hydraulic cylinder 5 and the seedling planting apparatus 3 are fixed for a long time, the shutoff valve 25 in FIG. 4 is tightened and closed.

As shown in FIG. 2, a balance-like bracket 36 is swingably supported around a horizontal axis P3, and a sensitivity adjusting lever 19 is provided on the upper portion of the bracket 36. One end of the outer 14b of the release wire 14 on the side is supported by a lower portion of the bracket 36. And the outer 37 of another release wire 37
The end of b is supported on the upper part of the bracket 36, and one end of the inner 37a is connected to the upper part of the balance arm 27 via a spring 38, and a continuously variable transmission for traveling (not shown)
The other end of the inner 37a is connected to the speed change lever 39 for use.

With the above structure, when the sensitivity adjusting lever 19 is operated to the sensitive side, the biasing force of the spring 38 for biasing the balance arm 27 and the spool 12 downward (to the left in FIG. 3) is weakened. At the same time, one end of the outer 14b moves to the left of the drawing sheet, the posture of the ground float 9 is directed downward, the ground area is increased, and the ground float 9 sensitively follows the unevenness of the rice field G. . Conversely, when the sensitivity adjusting lever 19 is operated to the insensitive side, the urging force of the spring 38 urging the balance arm 27 and the spool 12 to the lower side (to the left in FIG. 3) is strengthened, and the outer 14b is One end moves to the right in the drawing, the posture of the ground float 9 is directed upward, the ground area is reduced, and the ground following the unevenness of the ground float 9 becomes insensitive. And the shift lever 3
When the lower gear 9 is operated to the lower speed side, the inner 37a is returned, and the urging force of the spring 38 for urging the balance arm 27 and the spool 12 downward (to the left in FIG. 3) is weakened. It is in a state of sensitively following the ground on the unevenness of the rice field G. Conversely, when the shift lever 39 is operated to the high speed side, the urging force of the spring 38 for urging the balance arm 27 and the spool 12 downward (to the left in FIG. 3) is strengthened, and the unevenness of the ground float 9 is reduced. Ground following becomes insensitive.

Next, a configuration for providing resistance to the operation of the spool 12 of the control valve 11 will be described. As shown in FIG. 3, a first spring 16 (corresponding to a resistance applying means) that constantly urges the spool 12 of the control valve 11 to the lower left side in the drawing is provided. A second spring 17 (corresponding to resistance applying means) to which the end of the spool 12 comes into contact when reaching the set stroke position A on the right side of the drawing from the position to the right on the paper surface is provided. In this case, when the spool 12 is located between the neutral position and the set stroke position A on the ascending side, only the cutout portion 12c of the first land portion 12a communicates with a small opening degree,
When the spool 12 moves to the ascending side beyond the set stroke position A, the first land portion 12a is in a state where the entire opening is large.

With the above structure, the raising and lowering lever 21 is operated to the planting position, the seedling planting device 3 is slightly lowered with respect to the ground float 9 (set height), and the control valve 11 is moved.
Is located between the neutral position shown in FIG. 3 and the set stroke position A on the ascending side, only the resistance of the first spring 16 is reduced as shown by the solid line in FIGS. It will be linearly hung on the spool 12. Accordingly, in this state, the spool 12 is quickly moved upward with the lowering of the seedling planting device 3, but the first land 1
In 2a, only the notch 12c is in a small opening state in which it communicates. As a result, the hydraulic cylinder 5 starts to extend quickly as the seedling planting device 3 descends,
Starts its ascending operation, but its elongation speed is slow. In this case, the opening of the first land portion 12a at the notch portion 12c increases in proportion to the descending amount of the seedling planting device 3 relative to the ground float 9 (set height), and the hydraulic cylinder 5 As the supply amount of hydraulic oil to the hydraulic cylinder 5 increases, the extension speed of the hydraulic cylinder 5 increases.

Conversely, the seedling planting device 3 descends significantly with respect to the ground float 9 (set height), and the spool 12 of the control valve 11 is moved upward (to the right in the drawing) beyond the set stroke position A. In this case, the sum of the resistances of both the first spring 16 and the second spring 17 is linearly applied to the spool 12, as shown by the solid lines in FIGS. Therefore,
In this state, the spool 1
2, the first land portion 12a is opened and the opening degree is large. Thereby, the seedling planting device 3
With the downward movement of the hydraulic cylinder 5, the hydraulic cylinder 5 starts to extend slowly to start the raising operation of the seedling planting apparatus 3, but the extending speed is in a high state.

When the raising / lowering lever 21 is operated to the planting position, the seedling planting device 3 is raised with respect to the ground float 9 (set height), and the spool 12 of the control valve 11 is moved to the position shown in FIG.
In the case where the first spring 1 is located on the lower left side of the drawing from the neutral position shown in FIG.
The spool 12 is about to be moved down by only the urging force of No. 6. In this case, in a range where the amount of rise of the seedling planting device 3 from the neutral position is small, according to the amount of rise,
The degree of opening of the second land portion 12b at the notch portion 12c increases in proportion, the discharge amount of hydraulic oil from the hydraulic cylinder 5 increases, and the contraction speed of the hydraulic cylinder 5 increases. When the seedling planting device 3 rises significantly with respect to the ground float 9 (set height), the second land portion 12b
Is opened, the amount of hydraulic oil discharged from the hydraulic cylinder 5 increases rapidly, and the seedling planting device 3 is lowered at high speed.

As described above, when the planting device 3 is lowered with respect to the ground float 9 (set height), the control valve 1
As shown in FIG. 3 and FIG. 6, resistance is applied to one spool 12 in two stages, but the ground float 9 (set height)
On the other hand, when the seedling planting device 3 is raised, such an operation is not particularly performed, so that the descending operation side is relatively quickly performed as a whole with respect to the raising operation of the seedling planting device 3.
This is because, when raising and lowering the seedling planting device 3, if the seedling planting device 3 rises above the set surface from the rice field G, the planting depth becomes too shallow and floating seedlings may occur. In such a case, it is necessary to quickly lower the seedling planting device 3 to prevent the occurrence of floating seedlings.

[Alternative Embodiment] In the above embodiment, the control valve 11
6 is applied to the upward movement of the spool 12, and a linear urging force is applied to the downward movement of the spool 12. As shown on the side, a two-stage urging force may be applied. In this case, between the neutral position and the set stroke position on the descending side, the urging force of the spool 12 on the descending side is increased, and on the descending side beyond the set stroke position, the urging force of the spool 12 on the descending side is increased. Is configured to be weak.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is an overall side view of a riding rice transplanter.

FIG. 2 is a diagram showing a control valve and its operation system, and a linked state between a ground float and the control valve.

FIG. 3 is a vertical sectional front view of a case in which a control valve is provided.

FIG. 4 is a vertical cross-sectional front view of the vicinity of a rotary unit (a lift lever is in a neutral position) in a case in which a control valve is installed.

FIG. 5 is a vertical cross-sectional front view of the vicinity of a rotary part (a lifting / lowering lever is at a planting position) in a case in which a control valve is provided.

FIG. 6 is a diagram showing a state of a resistance and an urging force applied to a spool of a control valve.

[Explanation of symbols]

 Reference Signs List 3 Ground work device 5 Hydraulic cylinder 9 Height sensor 11 Control valve 12 Spool of control valve 14 Coupling means 16, 17 Resistance adding means G Ground A Set stroke position

Claims (1)

(57) [Claims] 1. A hydraulic cylinder (5) for raising and lowering a ground working device (3) with respect to a machine body, a control valve (11) for supplying and discharging hydraulic oil to and from the hydraulic cylinder (5), and a ground (G). And a height sensor (9) for detecting a height from the ground work device (3) to the ground work device (3). The more the detected value of the height sensor (9) deviates greatly from the set value to the descending side or the ascending side, When the spool (12) of the control valve (11) is largely operated on the ascending side or the descending side of the ground working device (3), the amount of oil supply / discharge to the hydraulic cylinder (5) increases, and the hydraulic cylinder (5) ) Is operated so that the height sensor (9) and the spool (12) of the control valve (11) are linked so as to be operated quickly.
4), the ground work device (3) is configured to be maintained at a set height from the ground (G), and the spool (12) of the control valve (11) is set to a neutral position and a raised position. When the spool (12) is located between the set stroke position (A) and the spool (12), a small resistance is given to the upward movement of the spool (12). A work vehicle ground work device lifting / lowering structure comprising resistance adding means (16), (17) for providing a large resistance to the movement of the spool (12) to the rising side when located on the rising side.