JPH02265404A - Hydraulic pressure circuit structure for working car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a working device connected to a traveling machine body by a single-acting hydraulic cylinder so that it can be driven up and down, and a sensor for detecting the height of the working device above the ground. Based on the results, the height of the work device above the ground is maintained at a set value (including an elevation control means for driving the hydraulic cylinder, and an operating mechanism that allows manual operation of the hydraulic cylinder with priority over the elevation control means). The present invention relates to a hydraulic circuit structure for a work vehicle equipped with.

[Conventional technology]

In the above-mentioned hydraulic circuit structure, there has conventionally been a structure in which a check valve and a fixed throttle are connected in parallel in the oil discharge side oil passage of the hydraulic cylinder (for example, Utility Model No. 62-97521
(see publication).

[Problem to be solved by the invention]

In the above conventional structure, when supplying pressure oil to the hydraulic cylinder to raise the working equipment greatly, consideration is given to supplying a large amount of hydraulic oil through the check valve to quickly perform the raising operation. When the work equipment is lowered, the hydraulic oil in the hydraulic cylinder is drained at high speed due to the weight of the work equipment, but by passing it through a fixed throttle, the speed is reduced to prevent the work equipment from descending rapidly. It is.

However, if the fixed aperture is set to a large aperture amount, when turning the headland during rice planting work, for example, when the working equipment is raised and turned, and then lowered, the lowering is performed slowly, making it difficult to carry out the work. There is a drawback that efficiency decreases, and on the other hand, if the amount of throttle is reduced, the lowering operation is performed quickly, but when planting, when the automatic lifting control is performed by the lifting control means, the following lifting and lowering of the hydraulic cylinder is required. This had the disadvantage that the motion became sensitive and a pitching phenomenon occurred.

Therefore, as a way to solve the problems mentioned above,
It has been considered to use a manually adjustable variable diaphragm instead of the fixed diaphragm. However, the above-mentioned improved structure has the drawback that the accuracy of restoring the aperture amount after adjustment is poor and it is difficult to maintain it in an appropriate state at all times, and the adjustment work is also troublesome.

An object of the present invention is to eliminate the above-mentioned problems, to quickly lower a working device from a greatly raised state, and to always perform automatic elevation control smoothly.

[Means to solve the problem]

A feature of the present invention is that, in the hydraulic circuit structure of the work vehicle described at the beginning, a plurality of oil passages each having a fixed throttle part are connected in parallel to the oil discharge side oil passage from the hydraulic cylinder, and each It is equipped with an oil passage switching mechanism that can be freely switched between a state in which only some of the parallel oil passages allow the passage of drained oil and a state in which all the parallel oil passages allow the passage of drained oil. , its actions and effects are as follows.

[For production]

In other words, when lowering the working equipment from a greatly raised position, by setting the oil passage switching mechanism to a state that allows drained oil to pass through all the parallel oil passages, the flow rate of drained oil increases and the speed is reduced. Can perform descending movements. When automatic elevation control is performed, the oil passage switching mechanism is set to allow drained oil to pass through only some of the oil passages, thereby allowing the drained oil to pass through only some of the fixed throttle sections. Therefore, the flow rate is always suppressed to a constant small flow rate.

〔Effect of the invention〕

Therefore, according to the present invention, although the working device can be lowered quickly and the automatic elevation control can be performed smoothly, it is only necessary to switch the oil passage switching mechanism to one of the states described above. This eliminates the need for cumbersome adjustment work. Moreover, since the amount of drained oil throttled is always maintained constant regardless of the switching operation described above, it has become possible to accurately adjust the amount of oil.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 6 shows a riding rice transplanter which is an example of a working vehicle according to the present invention. This rice transplanter has a seedling planting device (2), which is an example of a working device, which can be raised and lowered via a parallel link mechanism (1) at the rear of the riding-type traveling body, and the front and rear axis (Yl).
This link mechanism (1) is connected so that it can be rolled around, and this link mechanism (1) is extended by supplying pressure oil, and is operated by a single-acting hydraulic cylinder (3) that is shortened by draining the oil by the weight of the seedling planting device (2). It is configured to move up and down.

As shown in FIG. 7, a rolling lock member (4) for locking the rolling operation of the seedling planting device (2) is provided at the rear end of the link mechanism (1). is attached to the link mechanism (1) so as to be able to swing freely around the front and back axis (Y2) which is eccentric from the rolling axis (Yl), and swings sideways to support the seedling planting device (2).
) on the side of the seedling planting device (2) regardless of the lifting position of the
5) can be locked to lock the rolling operation, and 1. The seedling planting device (2) is swung upward and held in the locking portion (6) formed on the link mechanism (1) side.
) can be switched to a state that allows rolling operation.

The seedling planting device (2) is provided with a grounding float (7) as a sensor for detecting the height of the seedling planting device (2) from the ground, and based on the detection result of this grounding float (7), Elevation control means for driving the hydraulic cylinder (3) to maintain the height of the seedling planting device (2) above the ground is provided, and the hydraulic cylinder (13) can be driven manually with priority over the elevation control means. It is equipped with a convenient operating mechanism. To explain in detail, as shown in FIGS. 1, 4 and 5, a seedling planting device (2)
The grounding float (7) is pivotally supported in the planting transmission case (8), which also serves as a frame, so as to be able to swing up and down around the rear transverse support (X), and the front part of the grounding float (7) is connected to the planting transmission case (8), which also serves as a frame. Pivotally connected to a bracket (9) connected from the case (8) via bending links (10), (10),
The lower bending link (lO) and the sliding spool (11) of the hydraulic pressure control valve (v) of the hydraulic cylinder (3) are interlocked and connected. That is, a fork (13) that engages with a pin (12) fixed to a sliding spool (11) is connected to one end of a rotating shaft (14), and a balance arm is attached to the other end of the rotating shaft (14). (15) is fixed, and an operating wire (16) is connected to one end of the balance arm (15). Then, the control valve (v) maintains a neutral state in a state where the ground pressure of the ground float (7) and the biasing force of the downward biasing spring (17) are balanced, and the seedling planting device (2) is activated. It is configured to be set at a predetermined seedling planting height. When the vehicle body enters a deep part of the tiller and the height of the seedling planting device (2) from the ground decreases, the ground pressure of the ground float (7) increases and the operating wire (16) becomes loose, causing the balance arm to loosen. The sliding spool (11) is moved by a tension spring (18) stretched on the other end of (15).
) is switched to the pressure oil supply state, the seedling planting device (2) rises, and when the float ground pressure falls to the set value, the neutral state is restored. Further, when the body rises, the float ground pressure becomes weaker, the sliding spool (11) is switched to the oil draining state, and the seedling planting device (2) is lowered until it reaches the neutral state. In this way, the height of the seedling planting device (2) above the ground is maintained at the set value. The operating wire (16), the rotation shaft (1
4), the fork (13), springs (17), (18), etc. constitute the elevation control means.

A cylindrical shaft (19) is freely fitted onto the rotating shaft (14), and a control lever (20) is attached to one end of the cylindrical shaft (19).
), and a contact arm (21) that is connected to the pin (12) in a one-sided manner is fixed to the other end, and by operating the operation lever (20), the automatic lifting control operation can be performed. The structure is such that the sliding spool (11) can be operated preferentially to the pressure oil supply side. That is, when the operating lever (20) is operated to the raised position (u), the contact arm (21) presses the pin (12) and forcibly switches the sliding spool (11) to the pressurized oil supply state, The seedling planting device (2) rises significantly. And the operation lever (20)
When the contact arm (21
) controls the sliding spool (11) in a neutral state, and the ball detent mechanism (22) allows the seedling planting device (2) to be held at a predetermined height. Next, press the control lever (
20) to the lowered position (d), the abutment arm (21) separates from the pin (12) and the seedling planting device (2) descends, entering into an automatic elevation control state. The operating lever (20) is linked to the planting clutch (23), and when operated from the lowered position (d) to the planting clutch position (C), the planting clutch (23) is activated. Then, the seedling planting is configured to start operation. The operating mechanism is composed of the operating lever (20), the sleeve sleeve (19), the contact arm (21), and the like.

As shown in FIG. 1, the hydraulic cylinder (3
), a fixed throttle part (24a),
Two oil passages (2,) interposed with (24b).

(12) are connected in parallel, and each parallel oil line (l+)
, (11), an oil passage switching mechanism ( 25)
is provided. To explain in detail, the oil passage switching mechanism (25)
As shown in FIGS. 2 to 4, the switching spool (28) is equipped with a switching spool (28) that is rotatable with respect to a case part (27) fixedly attached to a control valve case (26). The annular oil passage (l) constantly connects the control valve side oil passage (l1) and the hydraulic cylinder side oil passage (14) via a first fixed constriction part (24a) having a diameter of about 0.9 mm.
1), and the two passages (z3) and (z4
) to form a radial switching oil passage (l1). Further, the switching spool (28) is provided with a swinging drive arm (29), and the swinging drive arm (29) and the middle part of the operating lever (20) are interlocked and connected via a rod (30). It is. and the operation lever (20)
When the switch is operated to the lowered position (d), the switching oil passage (1
6) are brought into communication, and the drained oil from the hydraulic cylinder (3) flows through the first and second fixed throttle portions (24a) and (24).
b) Since both are set in a state that allows passage, the flow rate of drained oil becomes large and the seedling planting device (2) quickly descends. Furthermore, when the operating lever (20) is operated to the planting clutch position (C), the switching oil passage (16) is in the oil passage cutoff state, and the cylinder waste oil is directed to the first fixed constriction part (24a).
) is set to pass only. Therefore, when the automatic lifting control is activated during planting work, the seedling planting device (12
) will be gradually lowered, and smooth vertical control can be performed without causing a pitching phenomenon. Furthermore, since the oil amount is controlled via a fixed throttle, it can always be maintained in an accurate state.

[Another example]

(2) As shown in FIGS. 8 and 9, the second fixed constriction part (24b) has a diameter of 2.0 mm (24
bl), about 2.3M (24bz) or about 3.
It may be configured to be switchable to either 0 mm (24 bs).

(2) The parallel oil passages (nt) and (j'g) are not limited to two, but may be three or more.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the hydraulic circuit structure of a working vehicle according to the present invention, and FIG. 1 is a hydraulic circuit diagram, FIGS. 2 and 3 are cross-sectional views of the oil passage switching mechanism, and A partially cutaway front view, FIG. 5 is a diagram showing the linkage of the elevation control means, FIG. 6 is an overall side view of the rice transplanter, FIG. 7 is a rear view of the rice transplanter, and FIG. 8 is an oil passage of another embodiment. A cross-sectional view of the switching mechanism and FIG. 9 are perspective views of the fixed throttle portion forming portion of another embodiment. (2)... Working device, (3)... Hydraulic cylinder, ( 7)...Sensor, (24a),
(24b)...Fixed aperture part, (25)...
...Oil passage switching mechanism, (21), (l2)...Oil passage.

Claims (1)

[Claims] A working device (2) is connected to the traveling machine by a single-acting hydraulic cylinder (3) so as to be able to move up and down. (2) Elevation control means for driving the hydraulic cylinder (3) in order to maintain the height above the ground at a set value, and the hydraulic cylinder (3) can be driven manually with priority over the elevation control means. This is a hydraulic circuit structure for a working vehicle that is provided with an operating mechanism, in which a fixed throttle part (24a), (2
4b) are connected in parallel, and each parallel oil path (l_1), (l_
2) Oil passages that can be freely switched between a state in which only some of the oil passages (l_1) allow the passage of waste oil and a state in which all parallel oil passages (l_1) and (l_2) allow the passage of waste oil. A hydraulic circuit structure of a work vehicle provided with a switching mechanism (25).