KR102707689B1 - Working machine lifting and working fluid take out hydraulic device of agricultural work vehicle - Google Patents

Abstract

A hydraulic device for lifting and hydraulically extracting a work piece of an agricultural work vehicle is disclosed. The hydraulic device according to the present invention comprises a configuration including a lift control valve unit that is mounted on the rear of an agricultural work vehicle and controls the supply of hydraulic fluid for lifting and lowering to a hydraulically driven three-point lift device, a hydraulic extraction valve unit that controls the extraction of hydraulic fluid out of the work vehicle for hydraulically driven external work equipment and is equipped to receive the hydraulic fluid with priority over the lift control valve unit based on the flow of hydraulic fluid, and a flow rate control valve unit that is installed between the hydraulic extraction valve unit and the lift control valve unit and has a bypass path formed therein for fluidly connecting the hydraulic extraction valve unit supply-side pressure line and the lift control valve unit supply-side pressure line, and has a flow rate control port that can control the opening amount of an input-side branch of the bypass path, so that the flow rate of the bypass path through the flow rate control port is controlled, and thus the flow rate bypassed to the lift control valve unit supply-side pressure line is controlled through the bypass path, thereby controlling the flow rate of the bypass path through the flow rate control port. The gist is that external work machine lifting and external hydraulic pressure extraction through the above-mentioned hydraulic extraction valve can be implemented simultaneously.

Description

{WORKING MACHINE LIFTING AND WORKING FLUID TAKE OUT HYDRAULIC DEVICE OF AGRICULTURAL WORK VEHICLE}

The present invention relates to a hydraulic device for lifting and hydraulically extracting a work machine of an agricultural work vehicle, and more particularly, to a hydraulic device for lifting and hydraulically extracting a work machine of an agricultural work vehicle, which can simultaneously implement lifting and hydraulically extracting an external work machine through a three-point lifting device at the rear of the work vehicle and external hydraulic pressure through a hydraulic extraction valve.

A work vehicle called a 'tractor' has a structure and characteristics that are advantageous for performing various tasks by attaching external work equipment to the hitch (hereinafter referred to as a 'three-point lifting device') at the rear of the body. For example, work equipment such as a rake, rotavator, plow, or harrow can be attached to the hitch to perform various agricultural tasks such as tilling, tilling, pest control, water pumping, and threshing.

The three-point elevator device can be driven to elevate by extending or conversely contracting the elevator cylinder constituting the three-point elevator device according to the flow control of the operating fluid (hereinafter referred to as “pressure fluid”) of the elevator control valve, which is operated by a signal output by the controller according to the operation of the lever of the control device around the tractor driver’s seat, and thereby the height of the external work device with respect to the ground can be adjusted.

At the rear of the tractor, a hydraulic extraction valve unit for extracting pressurized oil from inside the tractor is provided to supply the pressurized oil to the work machine as a power source for operating the external work machine. When the work machine is connected to the three-point elevator, the actuator on the work machine side is connected to the output port of the hydraulic valve unit via a hydraulic hose, so that the work machine is driven by the pressurized oil of the tractor main unit.

The above-mentioned hydraulic relief valve (100) applied to a tractor is a directional control valve that regulates the flow of hydraulic fluid by switching the internal flow path with an external operating force, and as shown in FIG. 1, it is configured with a plurality of directional control valves (110a to 110c) in a stacked configuration but connected to each other in a fluid-flow-capable manner, and is configured to receive hydraulic fluid before the lifting control valve (200) based on the flow of hydraulic fluid.

More specifically, looking at the external hydraulic extraction and external work machine lifting circuit configuration of a conventional tractor, as shown in Fig. 1, the two valves (100, 200) are configured to form a series circuit in the circuit so that the hydraulic extraction valve (100) can be supplied with hydraulic oil with priority over the lifting control valve (200) based on the flow of hydraulic oil. Therefore, in the past, the hydraulic oil had to be used sequentially.

That is, since the hydraulic fluid passing through the plurality of directional control valves (110a to 110c) is supplied to the lifting control valve (200), even if only one of the plurality of directional control valves is used, the three-point lifting device (300) located at the rear end does not operate, and therefore, two tasks (lifting and lowering of the work unit and external hydraulic extraction) cannot be performed simultaneously. For this reason, there is a problem in the past where the efficiency of the work is reduced and the working time is lengthened.

Japanese Patent Publication No. 2008-061552 (Published on March 21, 2008)

The technical problem to be solved by the present invention is to provide a hydraulic device for lifting and hydraulic extraction of a work machine of an agricultural work vehicle, which can simultaneously implement lifting of an external work machine through a three-point lifting device and external hydraulic extraction through a hydraulic extraction valve.

According to an embodiment of the present invention as a means of solving the problem,

It is a device that is installed at the rear of an agricultural work vehicle and enables the lifting and lowering of an external work tool using hydraulics and the driving of the work tool at the same time.

A lift control valve unit mounted on the rear of an agricultural work vehicle and controlling the supply of hydraulic fluid for lifting and lowering to a hydraulically driven three-point lift device;

A hydraulic extraction valve unit connected to the above three-point lifting device and configured to control the extraction of hydraulic fluid out of the work vehicle for driving an external work device driven by hydraulic pressure, and provided so that the hydraulic fluid can be supplied with priority to the above lifting control valve unit based on the flow of hydraulic fluid; and

It is composed of a configuration including a flow rate control valve unit which is installed between the hydraulic extraction valve unit and the lifting control valve unit, and has a bypass path formed therein for fluidly connecting the hydraulic extraction valve unit supply side pressure line and the lifting control valve unit supply side pressure line, and has a flow rate control port for controlling the opening amount of the path formed by the hydraulic extraction valve unit supply side pressure line;

By controlling the flow rate of the bypass path through the above-mentioned flow control port, the flow rate bypassed through the above-mentioned bypass path to the pressure line on the supply side of the elevation control valve unit is controlled, thereby providing a hydraulic device for elevation and hydraulic extraction of an agricultural work vehicle, in which elevation of an external work device through the above-mentioned three-point elevation device and external hydraulic pressure extraction through the above-mentioned hydraulic extraction valve are simultaneously implemented.

In an embodiment of the present invention, the hydraulic extraction valve unit may be configured to include a valve section having a plurality of directional control valves arranged in a vertically stacked manner in which a spool inside moves and a flow path state is switched by an operation signal input from the outside, and a valve cover having an internal flow path formed therein, which is connected to the upper portion of the uppermost directional control valve among the directional control valves arranged in a stacked manner and is connected to the flow path of the uppermost directional control valve.

In addition, in an embodiment of the present invention, the flow rate control valve unit may be coupled to the lower part of the lowest directional control valve among the directional control valves arranged in a stack so as to form a fluidic connection with the lowest directional control valve.

According to an embodiment of the present invention, a flow control valve unit is disposed between a hydraulic extraction valve unit and an elevator control valve unit, which forms a bypass path for fluidically connecting a hydraulic extraction valve unit supply-side pressure line and an elevator control valve unit supply-side pressure line, so that operation of a three-point elevator device and external hydraulic extraction through a hydraulic extraction valve can be implemented simultaneously with a simple additional configuration.

In other words, since the lifting and lowering work of an external work machine and a specific work using an external work machine can be performed simultaneously, the continuity and efficiency of the work can be improved and the work time can be significantly shortened. In addition, since the flow control valve unit is configured to be combined with the hydraulic discharge valve unit in the form of a single module, the cost loss and efforts to secure space that would otherwise occur if the flow control valve were configured separately can be eliminated.

Figure 1 is a hydraulic circuit diagram for external hydraulic extraction and external work machine lifting applied to conventional agricultural work vehicles.
FIG. 2 is a perspective view showing the rear of an agricultural work vehicle to which a hydraulic device for lifting and hydraulically extracting a work device according to an embodiment of the present invention is applied.
Figure 3 is an enlarged drawing of the hydraulic device for lifting and removing the working machine of Figure 2.
Figure 4 is a hydraulic circuit diagram of a hydraulic device for lifting and hydraulically extracting a working machine according to an embodiment of the present invention.
Figures 5 and 6 are operating state diagrams showing the flow of hydraulic oil (working fluid) according to the valve switching state of the hydraulic extraction valve unit.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The terminology used in the specification is only used to describe particular embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. It should be understood that the terms "comprises" or "has" as used herein specify that a feature, number, step, operation, component, part or combination thereof described in the specification is present, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Additionally, while the terms first, second, etc. may be used to describe various components, the components should not be limited by the terms. The terms are used only to distinguish one component from another.

In addition, terms such as “part,” “unit,” and “module” described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software.

In describing with reference to the attached drawings, identical components will be given the same reference numerals and duplicate descriptions thereof will be omitted. In addition, when describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

FIG. 2 is a perspective view showing the rear of an agricultural work vehicle to which a hydraulic device for lifting and hydraulically extracting a workpiece according to an embodiment of the present invention is applied, and FIG. 3 is an enlarged view of the hydraulic device for lifting and extracting a workpiece of FIG. 2. And FIG. 4 is a hydraulic circuit diagram of the hydraulic device for lifting and hydraulically extracting a workpiece according to an embodiment of the present invention.

Referring to FIGS. 2 to 4, a hydraulic device for lifting and hydraulic extraction of a work machine according to the present invention is a device that can simultaneously perform lifting and lowering operations of an external work machine using hydraulic pressure and operating the work machine, and largely includes a lifting control valve unit (30), a hydraulic extraction valve unit (20), and a flow rate control valve unit (10) that controls the flow rate of hydraulic fluid supplied between these valve units (20, 30).

The lift control valve unit (30) is not specifically shown, but can be attached to the upper surface or side surface of the lift unit cover at the upper rear end of the mission case. The lift control valve unit (30) is mounted at the rear of an agricultural work vehicle and controls the supply of hydraulic fluid for lift driving to a hydraulically driven three-point lift device (40), and is arranged in series on the circuit downstream of the hydraulic discharge valve unit (20) based on the flow of hydraulic fluid.

The lift control valve unit (30) is largely composed of a rising and falling main spool (34, 38), a rising and falling proportional solenoid (32, 36), and an unload valve (31), as shown in the circuit diagram of Fig. 4. When the driver moves the lift control lever to which an electric angle sensor is attached, the rising or falling proportional solenoid (32 or 36) operates correspondingly, and the rising or falling main spool (34, 38) opens or closes, causing the lifting cylinder to expand and contract, thereby driving the lifting arm (42R, 42L) of the three-point lifting device (40) to rise and fall.

In the case of the elevator arm stopping, the flow supplied from the hydraulic discharge valve unit (20) flows into the P port of the circuit diagram, but since the proportional solenoids (32, 36) for raising and lowering are closed, the shear pressure of the unload valve (31) increases, and accordingly, it is transmitted to the lower part of the spool through the pilot line (PL1) at the inlet of the unload valve (31), so that the spool of the unload valve (31) opens, and eventually, the flow supplied to the P port is completely discharged through the unload valve (31).

In the case of the elevator arm rising, the pressurized oil flowing into the P port is delivered to the rising main spool (34) through the pilot line (PL2) as the rising proportional solenoid (32) opens, thereby opening the rising main spool (34). Accordingly, the pressurized oil supplied through the P port is evenly supplied to a pair of left and right lifting cylinders (41R, 41L), causing the three-point lifting device (40) to rise, and ultimately causing the external working device connected to the three-point lifting device (40) to rise.

At this time, the unload valve (31) is kept closed by the hydraulic pressure transmitted through the pilot line (PL3) located between the rising main spool (34) and the check valve (39), so that the drain through the unload valve (31) is completely blocked, facilitating the supply of hydraulic pressure for the elevation of the three-point elevator (40). When the three-point elevator (40) reaches the position desired by the operator, the elevation proportional solenoid (32) is automatically closed and the elevation arm (42L, 42R) stops at the position desired by the operator.

The lowering of the elevator arm is implemented by the driver operating the elevator control lever downward from the current position. Specifically, when the elevator control lever located on the driver's seat is operated downward from the current position, the lowering proportional solenoid (36) opens and the hydraulic pressure of the P port is transmitted to the lowering main spool (38) through the pilot line (PL4), thereby moving the lowering main spool (38) to the open position.

Accordingly, the fluid filled in the lifting cylinder (41L, 41R) is discharged to the R port through the lowering main spool (38) and the lowering proportional solenoid (36), thereby implementing the lowering of the lifting arm (42L, 42R). Here, the lowering drain line is formed not only through the lowering main spool (38) but also through the lowering proportional solenoid (36), which is to enable the lowering speed to be increased further if necessary.

Meanwhile, the lowering main spool (38), the lowering proportional solenoid (36) and the unload valve (31) are connected to each other through the pilot line (PL5). Therefore, when the P port pressure is transmitted to the lowering main spool (38) through the lowering proportional solenoid (36), it is also transmitted to the unload valve (31), so that the unload valve (31) opens and closes repeatedly during lowering.

That is, when the pressure of the P line is discharged through the unload valve (31) during the lowering of the elevator arm, the unload valve (31) is repeatedly opened and closed appropriately according to the size of the pressure, and accordingly, the pressure of the P line is appropriately increased, and a pressure that is easy to maintain the lowering main spool (38) in the open position can be formed in the P line.

The hydraulic extraction valve unit (20) uses hydraulic pressure and controls the extraction of hydraulic fluid out of the work vehicle for driving an external work device connected to the three-point lifting device (40). The hydraulic extraction valve unit (20) can be installed on the upper surface of the lifting unit cover (43) as shown in FIGS. 2 and 3, and is provided so that the hydraulic fluid can be supplied to the lifting control valve unit (30) upstream of the lifting control valve unit (30) based on the flow of hydraulic fluid, with priority given to the lifting control valve unit (30), as shown in the hydraulic circuit diagram of FIG. 4.

The hydraulic extraction valve unit (20) is specifically composed of a valve section configured to have a plurality of, preferably three, directional control valves (20a to 20c) arranged in a vertically stacked manner, in which the spools inside are moved by a physical operation signal input from the outside to switch the flow path state, and a valve cover (20d) that is connected to the uppermost directional control valve (20c) among the directional control valves arranged in a stacked manner and has an internal flow path (250) formed therein that is connected to the flow path of the uppermost directional control valve (20c).

One of the plurality of directional control valves (20a to 20c) may be a detent double-acting valve capable of fixing the inner spool to a desired operating position by a detent ball when the inner spool is operated via an operating lever. In this case, since the spool can be fixed to a desired operating position by the detent ball, continuous hydraulic pressure supply to an external working device is possible. For example, it can be used in a working device equipped with a hydraulic motor, etc.

As shown in the diagram of Fig. 4, the directional control valves (20a to 20c) of a laminated configuration constituting the hydraulic extraction valve unit (20) are connected to each other so that the hydraulic fluid supplied through the P port of the flow control valve unit (10) can pass through or be supplied to the output ports (A ports and B ports of each control valve), and the actuator of a work machine that uses hydraulic pressure is connected to the output port of the desired directional control valve (20a to 20c) using a hydraulic hose.

That is, the hydraulic extraction valve unit (20) applied to the present invention is configured to include a plurality of directional control valves (20a to 20c) that are arranged in a vertically stacked manner, and neighboring directional control valves (20a to 20c) can be connected to each other with the same function to form a single straight flow path, and each can be configured to have an output port (A port and B port) for extracting operating fluid that is connected to an external work device-side actuator through a hydraulic hose.

Each directional control valve (20a to 20c) may be a manual type configured to regulate the flow of operating fluid by moving an internal spool in the axial direction with an operating lever as described above, but is not limited thereto, and may be configured as a solenoid type that is switched and driven by an external electrical signal, or may be a 6PORT 3WAY valve configured with an input port, a discharge port, a neutral port, and two output ports.

Accordingly, each directional control valve (20a to 20c) can control the position of the internal spool in a total of three directions, including switching to extend or retract an actuator of an external working device, such as a hydraulic cylinder, depending on the position of the internal spool according to the input of the operating force (or operating signal), and switching to a neutral position so that the hydraulic fluid can be supplied as is to the lifting control valve unit (30) through a neutral line formed in the valves.

For example, when one of the directional control valves (20a to 20c) is switched to the extension side of the actuator (60), the operating fluid supplied through the oil supply line (21) moves to the extension side hydraulic chamber of the actuator (60) controlled by the corresponding directional control valve to extend the actuator, and when the actuator (60) extends, the operating fluid in the opposite hydraulic chamber is drained to the oil tank (T) through the corresponding directional control valve and the oil drain line (24).

Conversely, when one of the directional control valves (20a to 20c) is switched to the retraction side of the actuator (60), the operating fluid supplied through the oil supply line (21) moves to the hydraulic chamber in the retraction direction of the actuator (60) controlled by the directional control valve to retract the actuator, and when the actuator retracts, the operating fluid in the hydraulic chamber on the opposite side is drained to the oil tank (T) through the directional control valve and the oil drain line (24).

When all directional control valves (20a to 20c) are fixed in a state where they are switched to the neutral side, the pressurized oil flowing into the oil supply line (21) passes through each directional control valve (20a to 20c) through a single neutral flow path (22) formed by the internal flow path (250) of the valve cover (20d) and the neutral port of each directional control valve (20a to 20c) being connected, and then is supplied to the aforementioned lift control valve unit (30) through the lift control valve unit supply side pressure line (15) of the flow control valve unit (10).

The flow control valve unit (10) is installed between the hydraulic extraction valve unit (20) and the elevation control valve unit (30), and controls the flow rate of the hydraulic fluid supplied directly to the elevation control valve unit (30) without going through the hydraulic extraction valve unit (20). In other words, it serves to divide the hydraulic fluid from the hydraulic pump (P) to the elevation control valve unit (30) and the hydraulic extraction valve unit (20) during the path of movement of the hydraulic fluid formed to supply the hydraulic fluid to the hydraulic extraction valve unit (20).

To this end, the flow control valve unit (10) has a bypass path (14) formed therein that connects the hydraulic extraction valve unit supply side pressure line (12) and the elevation control valve unit supply side pressure line (15) connected to the P1 port (input port) of the lowest directional control valve (20a to 20c) of the hydraulic extraction valve unit (20) so that fluid movement can occur, and includes a flow control port (13) provided to control the opening amount of the input side branch of the bypass path (14).

The flow control device (13) may be configured to have a rotary handle (130) that extends outside the valve block of the flow control valve unit (10), as shown in Fig. 3. In this case, the handle can be rotated left and right to stepwise adjust the flow rate directly supplied to the hydraulic discharge valve unit (20) and the lifting control valve unit (30), and through this, the operating speed of the three-point lifting device (40) and the external working device using hydraulic pressure can be appropriately adjusted.

That is, by controlling the opening amount of the input side branch of the bypass path (14) through the flow control port (13), the flow rate bypassed to the pressure line (15) on the supply side of the lift control valve unit through the bypass path (14) is controlled, and accordingly, the lifting of the external workpiece by the aforementioned three-point lifting device (40) controlled by the lift control valve unit (30) and the external hydraulic pressure extraction through the hydraulic pressure extraction valve unit (20) are implemented simultaneously.

The flow control valve unit (10) may preferably be coupled to the lowermost directional control valve (20a) among the directional control valves (20a to 20c) arranged in a stack to form the hydraulic extraction valve unit (20) as shown in Fig. 3, so as to form a fluidic connection with the lowermost directional control valve (20a). That is, it is preferable to form one module with the hydraulic extraction valve unit (20), thereby avoiding efforts such as increased costs or securing space.

The operation of the present invention will be examined with reference to FIGS. 5 and 6, and an example will be examined in which a double-acting cylinder is applied as an external working device-side actuator connected to a hydraulic extraction valve unit.

FIG. 5 and FIG. 6 are operating state diagrams showing the flow of hydraulic oil (working fluid) according to the valve switching state of the hydraulic extraction valve unit. As examples, the flow of hydraulic oil will be examined when the uppermost directional control valve (referred to as the “first directional control valve”) among the plurality of, preferably three directional control valves constituting the hydraulic extraction valve unit is switched to the actuator rising side and when all directional control valves are switched to the neutral side.

First, looking at the case where the first directional control valve (20a) is switched to the rising side of the actuator (60) as shown in Fig. 5, when the first directional control valve (20a) is switched to the rising side of the actuator (60), some of the hydraulic oil supplied by the hydraulic pump (P) moves through the oil supply line (21) to the internal flow path of the second directional control valve (20a) and into the hydraulic chamber (602) on the rising side of the actuator (60), and the hydraulic oil filled in the opposite hydraulic chamber (604) is drained to the oil tank (T) through the oil drain line (24).

In addition, the remaining portion of the hydraulic fluid supplied by the hydraulic pump (P) is supplied to the lifting control valve unit (30) through the bypass path (14) of the flow control valve unit (10), and is supplied as an operating fluid for raising or lowering the three-point lifting device (40) depending on the switching status of the valve elements constituting the lifting control valve unit (30), or is drained as is to the oil tank (T) side through the internal circuit when there is no operating command for the lifting device.

At this time, by controlling the opening amount of the input side branch of the bypass path (14) through the flow control port (13) of the flow control valve unit (10), the flow rate supplied to the hydraulic discharge valve unit (20) and the flow rate bypassed to the supply side pressure line (15) of the lift control valve unit through the bypass path (14) are controlled, so that the operating speed of the three-point lift device (40) and the actuator (60) can be controlled.

As shown in the following Figure 6, when all the directional control valves (20a to 20c) are switched to the neutral position, some of the hydraulic fluid supplied by the hydraulic pump (P) is supplied to the elevation control valve unit (30) side through the neutral line (22) formed by the directional control valves, and the remaining part is supplied directly to the elevation control valve unit (30) side through the bypass path (14) of the flow rate control valve unit (10). As a result, the hydraulic fluid supplied when the hydraulic extraction valve unit (20) is in the neutral position is supplied entirely to the elevation control valve unit (30).

According to the embodiment of the present invention as described above, some of the fluid is supplied to the hydraulic extraction valve unit side by the flow control valve unit between the hydraulic extraction valve unit and the elevation control valve unit, and the remaining part is supplied to the elevation control valve unit, so that the operation of the three-point elevation device and the operation of the external work machine using hydraulic pressure can be implemented simultaneously, and the operation speeds of the three-point elevation device and the external work machine can also be appropriately controlled.

In other words, since the lifting and lowering work of an external work machine and a specific work using an external work machine can be performed simultaneously, the continuity and efficiency of the work can be improved and the work time can be significantly shortened. In addition, since the flow control valve unit is configured to be combined with the hydraulic discharge valve unit in the form of a single module, the cost loss and efforts to secure space that would otherwise occur if the flow control valve were configured separately can be eliminated.

In the above detailed description of the present invention, only specific embodiments thereof have been described. However, it should be understood that the present invention is not limited to the specific forms mentioned in the detailed description, but rather should be understood to include all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

10: Flow control valve unit
12: Hydraulic discharge valve unit supply side pressure line
13: Flow control port 14: Bypass path
15: Lift control valve unit supply side pressure line
20: Hydraulic extraction valve unit
20a, 20b, 20c: Directional control valve 20d: Valve cover
21: Fuel line 22: Neutral line
24: Oil distribution line 30: Lifting control valve unit
31: Unload valve 32: Rising proportional solenoid
34: Rising main spool 36: Lowering proportional solenoid
38: Lowering main spool 39: Check valve
40: 3-point lifting device 41L, 41R: Lifting cylinder
42L, 42R: Lifting arm 60: External working machine actuator
P: Hydraulic pump T: Oil tank

Claims (3)

It is a device that is installed at the rear of an agricultural work vehicle and enables the lifting and lowering of an external work tool using hydraulics and the driving of the work tool at the same time.
A lift control valve unit mounted on the rear of an agricultural work vehicle and controlling the supply of hydraulic fluid for lifting and lowering to a hydraulically driven three-point lift device;
A hydraulic extraction valve unit connected to the above three-point lifting device and configured to control the extraction of hydraulic fluid out of the work vehicle for driving an external work device driven by hydraulic pressure, and provided so that the hydraulic fluid can be supplied with priority to the above lifting control valve unit based on the flow of hydraulic fluid; and
It is composed of a configuration including a flow rate control valve unit which is installed between the hydraulic discharge valve unit and the lifting control valve unit, and has a bypass path formed therein for fluidly connecting the hydraulic discharge valve unit supply side pressure line and the lifting control valve unit supply side pressure line, and has a flow rate control port for controlling the opening amount of the input side branch of the bypass path.
A hydraulic device for lifting and hydraulic extraction of a work piece of an agricultural work vehicle, in which the flow rate bypassed to the supply side pressure line of the lifting control valve unit through the above bypass path is controlled, and external work piece lifting through the above three-point lifting device and external hydraulic pressure extraction through the above hydraulic extraction valve are simultaneously implemented.
In paragraph 1,
The above hydraulic extraction valve unit,
A valve section having a configuration in which multiple directional control valves are arranged in layers one above the other, in which the internal spool moves and the euro state is switched by an operation signal input from the outside;
A hydraulic device for lifting and hydraulic extraction of a work piece of an agricultural work vehicle, characterized by comprising: a valve cover which is connected to the upper part of the uppermost directional control valve among the directional control valves arranged in a stack and has an internal flow path formed therein which is connected to the flow path of the uppermost directional control valve;
In the second paragraph,
A hydraulic device for lifting and hydraulic extraction of a work piece of an agricultural work vehicle, characterized in that a flow control valve unit is connected to the lowermost directional control valve among the directional control valves arranged in a stack so as to form a fluidic connection with the lowermost directional control valve.

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