JPH02186106A - Valve device - Google Patents

Abstract

PURPOSE:To reduce the cost by providing a transfer line communicating between the second passage and a control line, and a check valve which checks hydraulic flow from the control line provided at this transfer line in the direction to the second passage. CONSTITUTION:In combined operation, load pressure of a hydraulic cylinder 34 is led to the second passage 50 through load passages 46 and 47. And it is led to a control line 56 through a transfer passage 57 and a check valve 59, and load pressure of a hydraulic cylinder 35 is led to a passage 51 of the second passage through load passages 48 and 49. And it is further led to the control line 56 through a transfer line 58 and a check valve 60. At last, the larger pressure of the load pressures of hydraulic cylinders 34 and 35, that is, the maximum load pressure is taken out as control pressure in the control line 56. And this control pressure is given to pressure controller 37 and 40, whereby the pressure controllers 37 and 40 are lowered from the rise state opposing pump pressure, and pressures in the first passages 44 and 45 are raised respectively and controlled to the equal pressure. Therefore, it is not necessary to provide an expensive shuttle valve.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a valve device included in a civil engineering/construction machine having a plurality of actuators, such as a hydraulic excavator.

<Prior Art> FIG. 9 is a circuit diagram including an example of a conventional valve device of this type.
This is disclosed in Japanese Patent Application Laid-Open No. 57-110884.

The valve device shown in FIG. 9 has a pressure oil supply source consisting of a hydraulic pump 1 and an actuator 2 that controls the flow rate discharged from the hydraulic pump 1, and is driven by the pressure oil supplied from the hydraulic pump 1. The direction includes a flow control valve 5 for controlling the flow of pressure oil supplied to the hydraulic cylinders 3 and a pressure controller 6. Directional switching valve 1 including a switching valve 7, a flow control valve 8 that controls the flow of pressure oil supplied to the hydraulic cylinder 4, and a pressure controller 9.
0.

The above-mentioned directional control valves 7.10 each have a hydraulic pump 1.
a first passage 13.14 connected to these supply passages 11.12, and a load passage 15.14 connected to each of the hydraulic cylinders 3.4.
15a, 16.16a and each of the first passage 13.14 and the load passage I? 815.15a and 16.16a, and a second passageway 17.18 that can communicate with each of them.

Each of the flow control valves 5.8 described above closes the gap between the supply passage 11.12 and the first passage 13.14.
Or communicate via the built-in variable aperture part 19.20.21.22, and the variable aperture part 19.20.21.22
The flow rate of pressurized oil passing between the supply passage 11.12 and the first passage 13.14 is controlled according to the change in the amount of restriction of the second passage 17.18 and the load passage 15.15a,
16. Block or communicate with 16a, respectively.

Further, the pressure controller 6 described above has a first passage 13 and a second passage.
The pressure regulators 9 are arranged between the first passage 14 and the second passage 18, and these pressure regulators 6.9 are arranged in the control line 23.24. It can be driven by the control pressure guided by. The aforementioned control lines 23.24 are then connected via shuttle valves 25 to each of the second passages 17.18, that is to say to each of the load passages 15.15a, 16.16a, The maximum load pressure of the load pressures of the hydraulic cylinders 3.4 is taken out from the shuttle valve 25 and applied to each of the pressure controllers 6.9 as a common control pressure.

And further, the control conduit 23.24 is connected to the third passage 26.
This third passage 26 extends across each of the flow control valves 5.8 and is able to communicate with a tank 27.

In the valve device configured in this way, the directional control valve 7
．． By switching and driving each of the 10 flow rate control valves 5.8, the pressure oil of the hydraulic pump 1 is supplied to each supply passage 11.
．． 12, is led to the first passage 13.14 via the variable restrictor 19.21 or 20.22, thereby pushing the pressure regulator 6.9 upward in FIG. is supplied to the hydraulic cylinder 3.4 via the second channel 17.18, the load channel 15.16 or 15a, 16a, thereby producing a combined drive of the hydraulic cylinder 3.4.

During this combined drive, the larger of the load pressures of the hydraulic cylinders 3.4 is transferred to the pressure controller 6 via the shuttle valve 25 as a common control pressure via the control line 23.24. .9.

As a result, the pressure regulator 6.9 is lowered from the above-mentioned raised state against the pump pressure, and the pressures in the first passages 13, 14 are respectively increased and controlled to be equal to each other. Here, the pressure on the inlet side of the flow control valve 5.8 is equal to the pressure in the supply passage 11.12, that is, the pump pressure.

Also, the pressures on the outflow side, ie the pressures in the first passages 13, 14, are both equal as described above. As a result, the differential pressure across each of the flow control valves 5.8 is always equal. At this time, the pressures in the first passages 13 and 14 are equal to each other, and the pressures in the first passages 13 and 14 are
8 to one drive part of the actuator 2 which controls the flow rate of the hydraulic pump 1, and energizes the actuator 2 with a force due to the pressure difference between the pump pressure and the pressure in this first passage 13.14. A constant flow rate is supplied from the hydraulic pump l such that the force of the spring 29 is balanced. Therefore, the flow rate corresponding to the respective throttle amount of the variable restrictor 19.21 or 20.22 corresponding to the respective stroke amount of the flow control valve 5.8, that is, the opening amount of the hydraulic cylinder 3.
．． 4, it is possible to realize stable composite driving of the hydraulic cylinders 3.4 without affecting each other due to load fluctuations of the hydraulic cylinders 3.4.

Note that when the flow rate control valves 5.8 are in neutral, the control pressure in the control line 23.24 is transferred to the tank 27 due to the communication of the third passage 26 to the tank 27 due to the return of these flow rate control valves 5.8. be missed.

<Problems to be Solved by the Invention> Incidentally, in the conventional valve device configured as described above, the control pressure is taken out through the shuttle valve 25, and this shuttle valve 25 is generally expensive and expensive. Because of this, manufacturing costs tend to be high.

In particular, civil engineering and construction machines such as hydraulic excavators are usually provided with six or more actuators, such as a left travel motor, right travel motor, swing motor, boom cylinder, arm cylinder, packet cylinder, etc. A left running directional switching valve, a right running directional switching valve, a turning directional switching valve, a boom directional switching valve, an arm directional switching valve, and a packet directional switching valve are provided to control the drive of the vehicle. In such a case, for example, a shuttle valve is required that takes out the larger of the load pressure of the left-hand directional control valve and the load pressure of the right-hand directional control valve as control pressure, and furthermore, this shuttle valve A shuttle valve is required to take out the greater of the control pressure taken out and the load pressure of the swing directional control valve.Considering the same, five shuttle valves are required for six directional control valves. In addition to the complicated piping structure, manufacturing costs also increase.

The present invention has been made in view of the above-mentioned actual situation in the prior art, and its purpose is to take out the maximum load pressure of the load pressure of the actuator as the control pressure to drive the pressure controller without providing a shuttle valve. The objective is to provide a valve device that can.

Means for Solving the Problems To achieve this object, the present invention provides a supply passage connected to a pressure oil supply source, a load passage connected to an actuator, and a first passage connected to the supply passage. a passageway, a second passageway that can communicate with the first passageway and the load passageway, and a supply passageway and the first passageway that are closed or communicated through a built-in variable throttle part; a flow rate control valve that controls the flow rate of pressurized oil passing between the candy offering passage and the first passage according to a change in the amount of restriction of the flow rate, and closes or communicates between the second passage and the load passage; , a control pipe disposed between the first passage and the second passage, having a plurality of directional valves including a pressure controller for controlling the pressure in the first passage, and transmitting control pressure to the pressure controller. In the valve device, the valve device is equipped with a transmission pipe that connects the second passage and the control pipe, and the transmission pipe is equipped with a transmission pipe that connects the second passage and the control pipe. and a check valve for blocking the flow of pressure oil from the control pipe in the direction of the second passage.

<Function> Since the present invention has a structure in which the second passage of each directional control valve is connected to the control pipe via the transmission pipe and the check valve as described above, it is necessary to provide a shaft valve. No load passage,
The maximum load pressure of the load pressures of the actuator can be taken out as the control pressure for controlling the pressure controller through the second passage, and the structure can be simplified.

<Example> Hereinafter, the valve device of the present invention will be explained based on the drawings.

FIG. 1(a) is a circuit diagram including a first embodiment of the present invention.

As shown in FIG. 1(a), the valve device 30 constituting the first embodiment is connected to a hydraulic circuit of a civil engineering/construction machine such as a hydraulic excavator, for example, a variable displacement hydraulic pump 31, and a hydraulic pump 31. A pressure oil supply source 33 consisting of a regulator 32 that controls the flow rate discharged from the hydraulic pump 1, and a plurality of actuators driven by the pressure oil supplied from the hydraulic pump 1.
That is, it is provided in a hydraulic circuit comprising hydraulic cylinders 34 and 35.

The valve device 30 includes a flow control valve 36 that controls the flow of pressure oil supplied to the hydraulic cylinder 34, and a pressure controller 3.
7, a flow rate control valve 39 that controls the flow of pressure oil supplied to the hydraulic cylinder 35, and a directional control valve 41 that includes a pressure controller 40.

The above-described directional control valves 38.41 each have a first passage 44.45 connected to the hydraulic pump 31 and a load passage 46.4 connected to each hydraulic cylinder 34.35.
7,48,49 and a second passage 50.51 which can communicate with each of the first passages 44.45 and with each of the load passages 46.47.48.49.

Each of the above-described flow control valves 36 and 39 is
Variable throttle section 52.53.54.5 that closes or has a built-in space between the supply passage 42.43 and the first passage 44.45
5 and its variable apertures 52.53.54.
The supply passages 42, 43 and the first
The pressure oil flow rate passing between the second passage 50.51 and the load passage 46.47 is controlled.
．． 48 and 49 respectively.

Further, the pressure controller 37 described above is arranged between the first passage 44 and the second passage 50, and the pressure controller 40 is arranged between the first passage 44 and the second passage 50.
and the second passage 51, these pressure regulators 37,40 can be driven by a control pressure guided by a control line 56.

Further, this valve device 30 includes a transmission pipe 57 that communicates the second passage 50 and the control pipe 56, a transmission pipe 58 that communicates the second passage 51 and the control pipe 56, and a transmission pipe 58 that communicates the second passage 51 and the control pipe 56. road 57
A check valve 59 is provided in the transmission pipe line 58 and prevents the flow of pressure oil from the control pipe line 56 in the direction of the second passage 50, and a check valve 59 is provided in the transmission line 58 and prevents the flow of pressure oil from the control line 56 in the direction of the second passage 51. a check valve 60 that prevents the flow of pressure oil; a third passage 62 that can connect the control pipe 56 to the tank 61;
2, and are interlocked with the flow rate control valves 36.39, respectively, and take a communication position when all of these flow rate control valves 36.39 are neutral, and take a cutoff position when the flow rate control valves 36.39 are activated. This configuration includes switching valves 63a and 63b.

The regulator 32 constituting the pressure oil supply source 33 described above has a predetermined differential pressure between the pump pressure and the control pressure of the control line 56, that is, the maximum load pressure of the load pressures of the hydraulic cylinders 34 and 35. In other words, the differential pressure and spring 6
A flow rate control means is configured to control the flow rate of the hydraulic pump 31 so that the force of the hydraulic pump 31 is balanced with the force of the hydraulic pump 31.

In this first embodiment, by switching and driving the flow control valves 36, 39 of the directional switching valves 38, 41, the pressure oil of the hydraulic pump 31 is supplied to the respective supply passages 42, 42, 39, 39, 39, 36, 39, 39, 42, 39, 42, 42, 42, 42, 42, 30, 30, 30, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 400, 400, 400, 40,000,000,000.
43, a variable restrictor 52.53 or 54.55, which leads to the first passage 44.45, whereby the pressure regulator 3
7.40 is pushed upward in FIG.
7.49 to the hydraulic cylinder 34.35;
This results in a combined drive of the hydraulic cylinders 34,35.

During this combined drive, the load pressure of the hydraulic cylinder 34 is guided to the second passage 50 via the load passage 46, 47, and further via the transmission passage 57 and five check valves to the control pipe 56. The load pressure of the hydraulic cylinder 35 is guided to the load passage 4.
8.49 to the second passage 51, and is further led to the control line 56 via the transmission passage 58 and the check valve 60,
As a result, the larger of the load pressures of the hydraulic cylinders 34, 35, ie the maximum load pressure, is taken out as the control pressure in the control line 56. Then, this control pressure is applied to the pressure controller 37.40, whereby the pressure controller 37.40 is lowered from the above-mentioned rising state against the pump pressure.
The pressures in the first passages 44, 45 are respectively increased and controlled to be equal to each other.

Here, the pressure on the inlet side of the flow control valve 36.39 is equal to the pressure in the supply passage 42.43, that is, the pump pressure, and the pressure on the outlet side, that is, the pressure in the first passage 44.45, is also equal as described above. both are equal, thereby causing the flow control valve 36
．． 39, the differential pressures before and after each are always equal. At this time, the control pressure of the control line 56, that is, the hydraulic cylinder 34
．． The maximum load pressure of 35 is led to one drive part of the regulator 32, the pump pressure is led to the other drive part of the regulator 32, and the force due to the pressure difference between the pump pressure and the maximum load pressure and the spring that biases the regulator 32 are applied. A flow rate is supplied from the hydraulic pump 31 such that the force of 64 is balanced. Therefore, a flow rate is supplied to each of the hydraulic cylinders 34.35 according to the respective throttle amount, that is, the opening amount, of the variable throttle portions 52.54 or 53.55 corresponding to the respective stroke amounts of the flow control valves 36.39. Thus, stable combined driving of the hydraulic cylinders 34, 35 can be realized without affecting each other due to load fluctuations of the hydraulic cylinders 34, 35.

Since the control pipe 56 communicates with the tank via the switching valves 63a and 63b, the flow rate control valves 36 and 39
When in neutral, the control pressure in the control line 56 can be released to the tank 61, leaving the pressure regulators 37, 40 in an unloaded state.

The first embodiment configured in this manner uses relatively inexpensive check valves 59 and 60 and a transmission pipe 57 that can form a simple pipe.
．． Hydraulic cylinder 34.
The maximum load pressure of 35 can be taken out as the control pressure to drive the pressure controller 37.40, that is, the same function as a shuttle valve can be obtained without requiring an expensive shuttle valve or a complicated piping system, Manufacturing costs can be reduced. This effect is particularly noticeable when the first embodiment has a large number of actuators, such as in a hydraulic excavator.

FIG. 1(b) is a circuit diagram including a second embodiment of the present invention.

In this second embodiment, another switching valve 63C is provided in the third passage 62 that communicates the control pipe 56 and the tank 61, and the switching valves 63a and 63 are interlocked with the flow rate control valve 36.39.
b is connected to a hydraulic power source 63d via a throttle valve 63e, so that the downstream pressure of the throttle valve 63e is guided as the driving pressure of the switching valve 63c, and the switching valve 63b is connected to the tank 61.

In this configuration, similarly to the first embodiment described above, when the flow rate control valves 36 and 39 are switched, the switching valve 63
a, 63b are closed, and thereby the pressure of the hydraulic source 63d is applied as driving pressure to the switching valve 63c via the throttle valve 63e, and this switching valve 63C is closed.
6.39, the control pipe 56 is communicated with the tank 61 via the switching valve 63c, and the control pressure can be released to the tank 61.

FIG. 2 is a circuit diagram including a third embodiment of the present invention.

This third embodiment provides pressure control means, such as a pressure compensating valve 65, in a third passage 62 connecting the control line 56 to the tank 61. When the control pressure increases in the throttle valve portion of the pressure compensating valve 65, the flow rate also increases in proportion to the increase in control pressure, resulting in an increase in energy loss. Here, when the control pressure is P and the flow rate is Q, the energy loss is expressed as PXQ-α·P” (α co-constant).

In this third embodiment, when the control pressure increases, the flow rate Q flowing from the third passage 62 to the tank 61 is significantly restricted by the flow rate control section of the pressure compensation valve 65, thereby suppressing the above-mentioned energy loss. can do.

Note that if energy loss does not need to be considered, a throttle valve may be simply provided instead of the pressure compensation valve 65 as the pressure control means described above.

FIG. 3 is a cross-sectional view of a main part showing a fourth embodiment of the present invention;
The figure is a cross-sectional view taken along the line AA in FIG. 3.

The fourth embodiment shown in FIG. 3.4 is a directional switching system that includes a slidably provided flow control valve 70 and a pressure controller 71 provided corresponding to the flow 1 control valve 70. A valve 72 is provided in one casting member 73, and a directional control valve 76, which likewise includes a flow control valve 74 and a pressure regulator 75, is provided in one casting member 77. A directional valve 80 with a pressure regulator 79 is provided in one cast member 81 . As shown in FIG. 3, these cast members 73 and 77 are inserted between the front plate 82 and the end plate 83 via a seal member.
．． 81, and these cast members 73, 77, 81 are connected to each other.

Also, front plays 1 to 82, cast members 73.77.
81 and flow control valve 70.74.7.
A control conduit 84 is formed in a direction perpendicular to the sliding direction of the pressure controllers 71, 75.79, and the upper ends of the springs 85.86.
Caps 88.8, 9 to be screwed onto each of 7.81
1 series is attached to the lower end of 0.

The pressure oil supply source 91 connected to this fourth embodiment includes a variable displacement hydraulic pump 92 and a variable displacement hydraulic pump 9.
and a flow rate control means 93 for controlling the flow rate of No. 2.

Furthermore, the above-mentioned control line 84 is connected to a tank 95 via a third passage 94, in which a pressure control means, for example a throttle valve 96, is provided.

For example, inside the cast member 73, as shown in FIG. 98, a second passageway 99 that can communicate with the second passageway 98;
load passages 100 and 101 that can communicate with the passage 99 of the tank and are connected to an actuator such as a hydraulic cylinder (not shown), and a tank passage 10 that is connected to the tank 95 shown in FIG.
2.103, a transmission pipe 104 connecting the second passage 99 and the control pipe 84, and a transmission pipe 104 interposed in the transmission pipe 104 from the control pipe 84 to the second passage Ii'899 direction. A check valve 105 that prevents backflow of pressure oil is provided.
The upper end of the spring 106 shown in FIG. 5 is engaged with a cap 107 that is screwed into the cast member 73.

Note that the flow rate control valve 70 has a supply passage 97 and a first passage 9.
Variable throttle section 108.
109, and controls the flow rate of pressurized oil passing between the supply passage 97 and the first passage 98 in accordance with changes in the amount of restriction of the variable restriction parts 108 and 109. The load passages 100 and 101 are respectively closed off or communicated with each other. Further, the pressure controller 71 is disposed between the first passage 98 and the second passage 99 and can be driven by the control pressure guided by the control conduit 84.

The other cast members 77 and 81 shown in FIG. 3 have the same construction as the cast member 73 shown in FIG. 4, and are provided, for example, to drive different actuators.

The fourth embodiment configured in this way has the same basic configuration as the first embodiment, has the same effect as the first embodiment, and has one cast member in one direction. Since a switching valve is provided, another directional switching valve can be easily added by attaching and removing the end plate 83 and the like.

FIG. 5 is a sectional view of a main part showing a fifth embodiment of the present invention.

This fifth embodiment includes a slidable flow control valve 70.74.
．． 78 and directional valves 72, 76, 80, each with a corresponding pressure regulator 71, 75, 79, are provided in one casting part 110, the control line 111 being connected to the casting part 1.
10 and in a direction perpendicular to the sliding direction of the flow control valves 70, 74, 78. The other configurations are the same as the fourth embodiment shown in FIG. 3.4 described above.

The fifth embodiment configured in this manner also has the same configuration as the first embodiment described above, and exhibits the same effects as the first embodiment.

FIG. 6 is a cross-sectional view of essential parts showing the sixth embodiment of the present invention, and FIG.
The figure is a cross-sectional view taken along the line B--B in FIG. 6.

The sixth embodiment shown in FIG. 6.7 also includes a slidable flow control valve 70, 74, 78 and a corresponding pressure controller 7.
1.75.79 are provided in one cast member 110. And, the control conduit 112 is different from the cast member 110,
In addition, as shown in FIG.
It is set at 13. This member 113 includes each pressure controller 71, 75, 79 and check valve 10 as illustrated in FIG.
5, etc., and each pressure controller 71.
The illustrated upper ends of springs 85, 86, 87, etc. of 75.79 and the illustrated upper ends of springs 106, etc. of check valve 105, etc. are engaged with the lower end of member 113. Other configurations are described in Section 3 above.
This is equivalent to the fourth embodiment shown in FIG.

The embodiment configured in this manner has the same basic configuration as the first embodiment, so it has the same effect as the first embodiment, and the control pipe 112 is smaller than the cast member 110. Since the control pipe 112 is constructed by drilling holes in the member 113, manufacturing of the control pipe 112 is easy.
Since there is no need for a cap as shown in Figure 4, the number of parts is small and the structure is simple.

FIG. 8 is a sectional view of a main part showing a seventh embodiment of the present invention.

The seventh embodiment shown in FIG. 8 is, for example, a flow control valve 7.
Check valve 115 and transmission pipe #1 in pressure controller 71 according to
116 is provided. Other configurations are described in Section 6 above.
This is equivalent to the sixth embodiment shown in FIG.

In the seventh embodiment configured in this way, in addition to achieving the same effects as the fifth embodiment described above, the cast member 110
Also, it becomes unnecessary to process holes for mounting the transmission pipe line and the check valve in the member 113, thereby further reducing processing costs and making the member 113 smaller.

<Effects of the Invention> As described above, the valve device of the present invention is configured to include a relatively inexpensive check valve and a transmission pipe line that is easy to manufacture, so it does not require an expensive shuttle valve like the conventional one. The maximum load pressure of the load pressure of the actuator can be taken out as the control pressure for driving the pressure controller without any problem, and the manufacturing cost can be reduced compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1(a) is a circuit diagram including a first embodiment of the valve device of the present invention, FIG. 1(b) is a circuit diagram including a second embodiment of the present invention, and FIG. Circuit diagram including third embodiment, third
The figure is a sectional view of a main part showing a fourth embodiment of the present invention, FIG. 4 is a sectional view corresponding to the A-A arrow direction in FIG. 3, and FIG. 5 is a sectional view of a fifth embodiment of the present invention. 6 is a sectional view of essential parts showing the sixth embodiment of the present invention, and FIG. 7 is a sectional view taken along line BB in FIG. 6.
FIG. 8 is a sectional view of a main part showing a seventh embodiment of the present invention, and FIG. 9 is a circuit diagram including an example of a conventional valve device. 30... Valve device, 31... Variable capacity hydraulic pump, 32... Regulator (flow control valve), 33.91... Pressure oil supply source, 34.35・
...Hydraulic cylinder, 36.39.70.74.7
8...Flow rate control valve, 37.40.71.75.
79...Pressure controller, 38.41.72.76
．． 80... Directional switching valve, 42.43.97...
...Supply passage, 44.45.98...1st
passage, 46.47.48.49.100.101...
...Load passage, 50.51.99...Second passage, 52.53.54.55.108.109...
...Variable aperture section, 56.84.111.112...
...Control line, 57.58.104.114.116
・・・・・・Transmission pipe, 59.60.105.115・
...Check valve, 61.95 ...Tank, 6
2.94...Third passage, 63a, 63b, 6
3c...Switching valve, 63d...Hydraulic power source,
63e... Throttle valve, 93... Throttle valve (
pressure control means), 64.85.86.87.106...
... Spring, 65 ... Pressure compensation valve (pressure control means), 73.77.81.110 ... Casting member, 82 ... Front plate, 83. ...
...End plate, 88.89.90.107...
...Cap, 92...Hydraulic pump, 93...
...Flow rate control means, 102.103...Tank passage, 1 Fig. 1 63d; Residence right F; 斥, ωθ:,! Erigo K Figure 9

Claims (13)

[Claims] (1) A supply passage connected to a pressure oil supply source, a load passage connected to the actuator, a first passage connectable to the supply passage, and a first passage connected to the first passage and the load passage. The second passage, the supply passage, and the first passage are closed or communicated via a built-in variable throttle part, and the supply passage and the first passage are closed or communicated via a built-in variable throttle part. a flow control valve that controls the flow rate of pressurized oil passing between the first passage and the second passage and the load passage, and a flow control valve that closes or communicates between the second passage and the load passage; and the first passage and the second passage. and a pressure controller that controls the pressure in the first passage, and a control pipe that transmits control pressure to the pressure controller, the control pipe In the valve device for guiding the maximum load pressure of the load pressure of the actuator as the control pressure, the transmission pipe is provided with a transmission pipe connecting the second passage and the control pipe, and a control A valve device comprising a check valve that prevents pressure oil from flowing from the pipe line to the second passage direction. (2) having a third passage through which the control line can communicate with the tank; and with the third passage communicating the control line with the tank when all the directional control valves are in neutral; 2. The valve device according to claim 1, further comprising a switching valve that closes a gap between the control pipe and the tank when the switching valve moves from the neutral position. (3) It has a third passage that can connect the control pipe to the tank, and is equipped with a pressure control means for controlling the pressure of the pressure oil flowing through the third passage. The valve device according to claim (1). (4) The valve device according to claim (3), wherein the pressure control means is a throttle valve. (5) The valve device according to claim (3), wherein the pressure control means is a pressure compensation valve. (6) The pressure oil supply source includes a hydraulic pump, and a flow rate for controlling the flow rate of the hydraulic pump so as to maintain the differential pressure between the pump pressure and the maximum load pressure of the load pressures of the actuator at a predetermined value. 2. The valve device according to claim 1, further comprising a control means. (7) One directional switching valve that is equipped with a slidably provided flow rate control valve and a pressure controller that is provided in correspondence with this flow rate control valve is provided in one cast member, and this cast member is The valve device according to claim 1, wherein a plurality of valve devices are connected to form one structure. (8) A control pipe is provided in each cast member in a direction perpendicular to the sliding direction of the flow control valve, and these control pipes are communicated with each other. ) The valve device described. (9) A claim characterized in that a single cast member includes a plurality of directional switching valves each including a slidably provided flow control valve and a pressure controller provided corresponding to the flow control valve. The valve device according to item (1). (10) The valve device according to claim (9), characterized in that a control conduit is provided within the cast member in a direction orthogonal to the sliding direction of the flow control valve. (11) The valve device according to claim (1), wherein the control conduit is arranged in a member different from the cast member. (12) The valve device according to claim (1), wherein the transmission conduit and the check valve are provided in the cast member. (13) The valve device according to claim (1), wherein the pressure controller is provided with a transmission conduit and a check valve.