Directional control hydraulic valve and system including same

Abstract

The present invention relates to a directional control hydraulic valve and a hydraulic system including the same. [Solution] The directional control hydraulic valve and hydraulic system including the same according to the present invention include a first valve that controls the flow of fluid flowing in from a first input port in conjunction with a solenoid valve that can be switched between energized (on) and de-energized (off), and a second valve that is connected to the first valve and controls the flow of fluid flowing in from the first valve using fluid flowing in from a second input port or a third input port, and at least a portion of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port or the third input port. The hydraulic system can also be configured with two or more directional control valves including the same, thereby achieving multiplexing of the hydraulic system.

Description

[Technical field]

[0001] The present invention relates to directional control hydraulic valves and systems including same. [Background technology]

[0002] In various industrial fields that use hydraulics as a power source, stable operation of hydraulic systems can improve productivity and ensure safety. In particular, the application of hydraulic systems is essential when operating heavy-load and large-capacity machines, and a system error caused by the failure of any part can result in significant human or material losses.

[0003] In this regard, various types of hydraulic trip systems are known. In particular, the circuit diagram for realizing a 2 out of 2 or 2 out of 3 type trip system, which is commonly used among trip systems, is complex, and a large number of components each performing a different function are required to realize the circuit diagram.

[0004] Furthermore, the trip system must always maintain a controlled state and respond to trip signals that occur intermittently. However, if the system is maintained for a long period of time, and a solenoid fails or a valve sticks, the valve may malfunction in a situation that is not a normal trip signal, resulting in unnecessary losses. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT INVETION The present invention has been made to solve the above-mentioned problems of the prior art, and has an object to provide a directional control hydraulic valve that opens and closes by line contact.

[0006] The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an entire system including the directional control hydraulic valve.

[0007] The object of the present invention is not limited to the above-mentioned object, and other unmentioned object will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the directional control hydraulic valve system of the present invention is a directional control hydraulic valve system in which any one directional control hydraulic valve is connected to at least two other directional control hydraulic valves, the directional control hydraulic valve includes a first valve that controls the flow of a fluid flowing in from a first input port in cooperation with a solenoid valve that can be switched to energized (on) or de-energized (off), and a second valve that is connected to the first valve and controls the flow of a fluid flowing in from the first valve by a fluid flowing in from a second input port or a third input port, and is characterized in that at least a portion of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port or the third input port.

[0009] In this case, the hydraulic system may further include a trip valve that controls an emergency stop of the hydraulic system in cooperation with the directional control hydraulic valve, and when at least three directional control hydraulic valves are provided, the trip valve trips only when at least two of the solenoid valves provided in each of the directional control hydraulic valves are in an operating state.

[0010] Furthermore, in order to achieve the above-mentioned object, the directional control hydraulic valve of the present invention includes a first valve that controls the flow of fluid flowing in from a first input port in cooperation with a solenoid valve that can be switched between energized (on) and de-energized (off), and a second valve that is connected to the first valve and controls the flow of fluid flowing in from the first valve by fluid flowing in from a second input port or a third input port, and is characterized in that at least a portion of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port or the third input port.

[0011] In this case, the first valve may include a first plunger that is displaced by the fluid flowing in from the first input port or the solenoid valve, a first piston that is displaced by the fluid flowing in from the first input port or the restoring force of a first elastic body, a first body that is displaced by the first plunger and the first piston and determines the flow of the fluid flowing in from the first input port depending on the amount of displacement, and a first seat that abuts against the first body as it is displaced to determine the amount of displacement of the first body.

[0012] In this case, the first valve may include a first line providing a path for fluid flowing in from the first input port, a second line branching off from the first line providing a path in the direction of the first plunger, and a third line branching off from the first line providing a path in the direction of the first piston.

[0013] Alternatively, the first body may have a circular or wedge-shaped cross section, or may be formed in a poppet shape so as to come into line contact with a portion of the first seat as the first body moves.

[0014] The second valve can include a second plunger displaced by the fluid flowing in from the first input port, a second piston displaced by the fluid flowing in from the second input port or the restoring force of a second elastic body, a third piston displaced by the fluid flowing in from the third input port or the restoring force of a third elastic body, a second body displaced by at least one of the second plunger, the second piston, or the third piston and determining the flow of the fluid flowing in from the first valve in accordance with the amount of displacement, and a second seat abutting against the second body as it is displaced to determine the amount of displacement of the second body.

[0015] In this case, the first valve may include a fourth line branching off from a first line providing a path for fluid flowing in from the first input port and providing a path in the direction of the second plunger.

[0016] Alternatively, the second valve may include an eighth line providing a path for fluid entering from the second input port towards the second piston.

[0017] Alternatively, the second valve may include a ninth line providing a path for fluid entering from the third input port towards the third piston.

[0018] Alternatively, the second body may have a circular or wedge-shaped cross section, or may be formed in a poppet shape so as to come into line contact with a portion of the second seat as the second body moves.

[0019] The device may further include a fifth line providing a path for fluid through the first valve toward the first output port.

[0020] In this case, a sixth line branching from the fifth line and providing a path in the direction of the second valve may be further included.

[0021] The pump may further include a seventh line providing a path for the fluid that has passed through the second valve to be discharged to a second output port. Effect of the Invention

[0022] The directional control hydraulic valve and the system including the same according to the present invention for solving the above-mentioned problems have the following advantages.

[0023] Even if a switching phenomenon occurs in some of the multiple solenoid valves due to a self-fault, the trip system will not operate and control of the turbine can be maintained.

[0024] Also, separate maintenance or testing can be performed on only some of the solenoid valves.

[0025] Moreover, by unifying the components, manufacturing and maintenance are more advantageous than in the past.

[0026] In addition, the gap between the body and the seat of the directional control hydraulic valve can be eliminated, preventing foreign matter from entering and causing adhesion.

[0027] Also, the oil leakage into the gap between the body and the seat of the directional control hydraulic valve can be minimized.

[0028] Also, by preventing adhesion of foreign matter and oil leakage, the reliability of the directional control hydraulic valve can be improved.

[0029] Even if some of the solenoid valves are stuck and cannot be switched to a trip signal, the trip system can still function properly if at least two valves are operating.

[0030] The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. [Brief description of the drawings]

[0031] [Figure 1] FIG. 2 is a diagram showing the state and fluid flow of the directional control hydraulic valve of the present invention when the solenoid valve is in an energized (on) state. [Diagram 2] FIG. 2 is a diagram showing the state and fluid flow of the directional control hydraulic valve of the present invention when the solenoid valve is in a de-energized (off) state. [Diagram 3] FIG. 2 is a diagram showing the state and fluid flow of the directional control hydraulic valve of the present invention when the solenoid valve is in a de-energized state. [Figure 4]FIG. 2 is a diagram showing a case where the directional control hydraulic valve of the present invention is connected in a 2 out of 3 type and each solenoid valve is in an excited state. [Diagram 5] FIG. 2 is a diagram showing a case where the directional control hydraulic valve of the present invention is connected in a two-out-of-three configuration, and one of the solenoid valves is in a non-excited state. [Figure 6] FIG. 2 is a diagram showing a case where the directional control hydraulic valve of the present invention is connected in a two-out-of-three type, and at least two solenoid valves are in a non-excited state. [Figure 7] FIG. 2 illustrates a system including the directional control hydraulic valve of the present invention when the solenoid valve is in an energized state. [Figure 8] FIG. 2 illustrates a system including the directional control hydraulic valve of the present invention when the solenoid valve is in a de-energized state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a directional control hydraulic valve and a system including the same according to the present invention will be described with reference to the accompanying drawings and examples. However, the present invention is not limited to these examples.

[0033] Like reference numbers refer to like elements throughout the specification.

[0034] The directional control hydraulic valve of the present invention may include a first valve and a second valve.

[0035] The first valve can be linked to a solenoid valve that can be switched on or off to control the flow of fluid entering from the first input port 180 .

[0036] The second valve is connected to the first valve and can control the flow of fluid flowing in from the first valve by the fluid flowing in from the second input port 280 or the third input port 290.

[0037] Then, at least a portion of the fluid that has passed through the first valve is discharged to a first output port 190 and can flow into the second input port 280 or the third input port 290 connected to the first output port 190.

[0038] Specifically, a portion of the fluid that has passed through the first valve may flow to the first output port 190 along a fifth line 50 that provides a path for the fluid that has passed through the first valve in the direction of the first output port 190.

[0039] The remainder of the fluid except for the fluid flowing to the first output port 190 can flow into the second valve through a sixth line 60 that branches off from the fifth line 50 and provides a path in the direction of the second valve.

[0040] The first valve may include a first plunger 110, a first piston 120, a first body 130, a first seat 140, and a first frame that provides a space for these components to operate in conjunction with each other internally.

[0041] In addition, for the flow of fluid through the first valve, a first line 10, a second line 20, and a third line 30 which are paths through which the fluid flows may be included.

[0042] The first line 10 provides a path for the fluid flowing in from the first input port 180, and the second line 20 may branch off from the first line 10 to provide a path in the direction of the first plunger 110. And, the third line 30 may branch off from the first line 10 or the second line 20 to provide a path in the direction of the first piston 120.

[0043] The first plunger 110 can be displaced by fluid entering from the first input port 180 or by the solenoid valve.

[0044] For example, the first plunger 110 may be movably provided at one end inside the first frame. The fluid flowing in through the first input port 180 may flow toward the first plunger 110 along a path provided by the first line 10 and the second line 20, and may flow into a space between the first plunger 110 and the first frame. In this case, when the solenoid valve is in an excited state, the first plunger 110 may move in a first direction due to the fluid flowing in the space between the solenoid valve, the first plunger 110, and the first frame.

[0045] The first piston 120 can be displaced by the fluid flowing in from the first input port 180 or by the restoring force of a first elastic body 125 .

[0046] For example, the first elastic body 125 may be provided at the other end of the inside of the first frame facing the first plunger 110. The first piston 120 may be provided movably inside the first frame so that the restoring force of the first elastic body 125 is transmitted. The fluid may flow along the third line 30 into a space between the first piston 120 and the first frame in which the first elastic body 125 is provided. In this case, when the solenoid valve is in a non-excited state, the sum of the magnitude of the hydraulic pressure applied to the first piston 120 by the fluid and the magnitude of the restoring force of the first elastic body 125 is greater than the magnitude of the hydraulic pressure applied to the first plunger 110 by the fluid, so that the first piston 120 may move in a second direction opposite to the first direction.

[0047] The first body 130 is displaced by the first plunger 110 and the first piston 120, and the flow of the fluid flowing in from the first input port 180 can be determined according to the amount of displacement.

[0048] Specifically, the first body 130 may include a cylindrical first rod member 131 between the first plunger 110 and the first piston 120, and the first contact members 135 at both ends of the first rod member 131. In this case, it is preferable that the first contact member 135 has a circular or wedge-shaped cross section or is formed in a poppet shape so as to come into line contact with a part of the first seat 140 as the first body 130 moves.

[0049] The first sheet 140 comes into contact with the first body 130 as the first body 130 is displaced, thereby determining the amount of displacement of the first body 130 .

[0050] That is, the first sheet 140 is fixed at a specific position inside the first frame, and can abut against the first sheet 140 while the first body 130 is moving, thereby limiting the amount of displacement of the first body 130.

[0051] The second valve may include a second plunger 250, a second piston 210, a third piston 220, a second body 230, a second seat 240, and a second frame that provides a space for these components to operate in conjunction with each other internally.

[0052] Also, for fluid flow in the second valve, an eighth line 80 and a ninth line 90 may be included as paths through which the fluid flows.

[0053] The eighth line 80 may provide a path for fluid entering from the second input port 280 in the direction of the second piston 210. And, the ninth line 90 may provide a path for fluid entering from the third input port 290 in the direction of the third piston 220.

[0054] The second plunger 250 can be displaced by fluid entering through the first input port 180 .

[0055] For example, the second plunger 250 may be movably provided at one end inside the second frame. Then, the fluid may flow toward the second plunger 250 along a fourth line 40 that branches from a first line 10 that provides a path for the fluid flowing in from the first input port 180 and provides a path toward the second plunger 250, and may flow into a space between the second plunger 250 and the second frame to pressurize the second plunger 250.

[0056] The second piston 210 can be displaced by the fluid flowing in from the second input port 280 or by the restoring force of a second elastic body 215 .

[0057] The third piston 220 can be displaced by the fluid flowing in from the third input port 290 or by the restoring force of a third elastic body 225 .

[0058] For example, it is preferable that the third elastic body 225, the third piston 220, the second elastic body 215, and the second piston 210 are arranged in this order in the second frame. The second piston 210 and the third piston 220 may be provided movably. When a fluid flows into the second input port 280, the fluid may flow between the third piston 220 and the second piston 210 along the eighth line 80 to pressurize the second piston 210. When a fluid flows into the third input port 290, the fluid may flow between an end of the second frame and the third piston 220 along the ninth line 90 to pressurize the third piston 220. At this time, when the fluid flows into the second input port 280 or the third input port 290, the sum of the magnitude of the hydraulic pressure applied to the second piston 210 by the fluid and the magnitude of the restoring force of the second elastic body 215, or the sum of the magnitude of the hydraulic pressure applied to the third piston 220 by the fluid and the magnitude of the restoring force of the third elastic body 225 is greater than the magnitude of the hydraulic pressure applied to the second plunger 250 by the fluid via the fourth line 40, so that the second piston 210 or the third piston 220 can move in the direction of the second plunger 250.

[0059] The second body 230 is displaced by at least one of the second plunger 250, the second piston 210, or the third piston 220, and the flow of fluid flowing in from the first valve can be determined depending on the amount of displacement.

[0060] Specifically, the second body 230 may include a cylindrical second rod member 231 between the second plunger 250 and the second piston 210, and a second contact member 235 at one end of the second rod member 231. In this case, it is preferable that the second contact member 235 has a circular or wedge-shaped cross section or a poppet-shaped cross section so as to come into line contact with a part of the second seat 240 as the second body 230 moves.

[0061] The second sheet 240 comes into contact with the second body 230 as the second body 230 is displaced, thereby determining the amount of displacement of the second body 230 .

[0062] That is, the second sheet 240 is fixed at a specific position inside the second frame, and can abut against the second sheet 240 while the second body 230 is moving, thereby limiting the amount of displacement of the second body 230.

[0063] The fluid that has passed through the second valve can then be discharged to the second output port 270 along a seventh line 70 that provides a path for the fluid that has passed through the second valve to be discharged to the second output port 270.

[0064] The relationship and interlocking between the components of the directional control hydraulic valve of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a diagram showing the state and fluid flow of the directional control hydraulic valve of the present invention when the solenoid valve is in an excited (on) state. Figures 2 and 3 are diagrams showing the state and fluid flow of the directional control hydraulic valve of the present invention when the solenoid valve is in a non-excited (off) state.

[0065] As shown in FIG. 1, when the solenoid valve is in an excited state, the sum of the pressure applied to the first plunger 110 by the solenoid valve and the hydraulic pressure flowing between the first plunger 110 and the first frame through the second line 20 is greater than the sum of the pressure of the fluid applied to the first piston 120 through the third line 30 and the restoring force of the first elastic body 125. Therefore, the first contact member 135 of the first body 130 can move toward the first plunger 110 until a part of it abuts against the first seat 140. And the fluid flowing into the inside of the first frame through the first line 10 cannot flow between the first contact member 135 of the first body 130 and the first seat 140.

[0066] Next, as shown in FIG. 2, when the solenoid valve is switched to a non-excited state, the pressure applied to the first plunger 110 by the solenoid valve is removed. At this time, the sum of the magnitude of the hydraulic pressure applied to the first piston 120 by the fluid and the magnitude of the restoring force of the first elastic body 125 is greater than the magnitude of the hydraulic pressure applied to the first plunger 110 by the fluid. Therefore, the first contact member 135 of the first body 130 becomes farther away from the first seat 140. And, the fluid flowing into the inside of the first frame through the first line 10 can move along the fifth line 50 through the gap between the first contact member 135 of the first body 130 and the first seat 140.

[0067] Of the fluid flowing along the fifth line, a portion travels along the sixth line 60 towards the second valve, and the remainder of the fluid is discharged to the first output port 190 .

[0068] Finally, as shown in FIG. 3, the fluid discharged to the first output port 190 can flow into the second input port 280 or the third input port 290 connected to the first output port 190. As described above, when the fluid flows into the second input port 280, the sum of the pressure of the fluid flowing between the second piston 210 and the third piston 220 to pressurize the second piston 210 and the restoring force of the second elastic body 215 is greater than the pressure that pressurizes the second plunger 250 along the fourth line 40. Therefore, the second contact member 235 of the second body 230 becomes farther away from the second seat 240. And, the fluid flowing into the inside of the second frame through the sixth line 60 can move to the second output port 270 along the seventh line 70 via the gap between the second contact member 235 of the second body 230 and the second seat 240. In a similar manner, when the fluid flows into the third input port 290, the sum of the pressure of the fluid flowing between the end of the second frame and the third piston 220 to pressurize the third piston 220 and the restoring force of the third elastic body 225 is greater than the pressure that pressurizes the second plunger 250 along the fourth line 40. Therefore, the second contact member 235 of the second body 230 becomes farther away from the second seat 240. And, the fluid flowing into the inside of the second frame through the sixth line 60 can move to the second output port 270 along the seventh line 70 via the gap between the second contact member 235 of the second body 230 and the second seat 240.

[0069] In this case, it will be obvious to those skilled in the art that whether the fluid discharged to the first output port 190 flows into the second input port 280 or the third input port 290 can be formed in various ways depending on the installation environment, etc.

[0070] With reference to Fig. 4 to Fig. 6, the operation of the directional control hydraulic valve of the present invention when multiple directional control hydraulic valves are connected in a so-called 2 out of 3 configuration will be described. Fig. 4 is a diagram showing a case where the directional control hydraulic valves of the present invention are connected in a 2 out of 3 configuration and each solenoid valve is in an excited state, and Fig. 5 is a diagram showing a case where the directional control hydraulic valves of the present invention are connected in a 2 out of 3 configuration and one solenoid valve is in a non-excited state. And Fig. 6 is a diagram showing a case where the directional control hydraulic valves of the present invention are connected in a 2 out of 3 configuration and at least two solenoid valves are in a non-excited state.

[0071] For ease of explanation, respective directional control hydraulic valves are shown at 1001, 1002, 1003, which may be configured to have the same or similar functions as the directional control hydraulic valves of the present invention described above.

[0072] As shown in FIG. 4, when all the solenoid valves are in an excited state, the fluid flowing into each of the first input ports is blocked between the first contact member of the first body and the first seat and cannot move.

[0073] 5, when any one of the solenoid valves 1001 is in a de-energized state, the fluid flowing into the first input port of 1001 passes through the first valve of 1001 and is discharged to the first output port of 1001. The first output port of 1001 flows to the second input port of 1002 and the third input port of 1003.

[0074] 6, when the two solenoid valves 1001, 1002 are in a non-energized state, the fluid flowing into the first input port of 1001 is discharged to the first output port of 1001 by the driving of the directional control hydraulic valve described above. Similarly, the fluid flowing into the first input port of 1002 is discharged to the first output port of 1002.

[0075] Hereinafter, a system including the above-mentioned directional control hydraulic valve of the present invention will be described with reference to Figs. 7 and 8. In relation to the system including the directional control hydraulic valve of the present invention described below, the description of the directional control hydraulic valve can be substituted for the description of the directional control hydraulic valve of the present invention described above. That is, when the terms used in the system including the directional control hydraulic valve of the present invention described below are the same as the terms used in the directional control hydraulic valve of the present invention described above, they can be understood as the same or similar configuration having the same or similar purpose and achieving the same or similar effect. Fig. 7 is a diagram showing a system including the directional control hydraulic valve of the present invention when the solenoid valve is in an excited state. And Fig. 8 is a diagram showing a system including the directional control hydraulic valve of the present invention when the solenoid valve is in a non-excited state.

[0076] The directional control hydraulic valve system of the present invention is characterized in that any one directional control hydraulic valve is connected to at least two other directional control hydraulic valves, and in this case, the directional control hydraulic valve includes a first valve that controls the flow of a fluid flowing in from a first input port in cooperation with a solenoid valve that is switched to energized (on) or de-energized (off), and a second valve that is connected to the first valve and controls the flow of a fluid flowing in from the first valve by a fluid flowing in from a second input port or a third input port, and at least a part of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port or the third input port.

[0077] Also, the directional control hydraulic valve system further includes a trip valve that controls an emergency stop of the turbine in cooperation with the directional control hydraulic valve, and when at least three directional control hydraulic valves are provided, the trip valve operates only when at least two of the solenoid valves provided in each of the directional control hydraulic valves are in a de-energized state.

[0078] That is, the directional control hydraulic valve system of the present invention can connect the above-mentioned directional control hydraulic valves of the present invention in a two-out-of-three type. The two-out-of-three type connection can be understood as the trip valve being operated when the solenoid valves provided in two of the three directional control hydraulic valves are de-energized (off), as in the conventional case. However, this is merely one preferred configuration, and the case where the trip valve is operated when the solenoid valve is energized (on) can also be considered, which is obvious to a person of ordinary skill in the art.

[0079] For example, the trip valve does not operate when the solenoid valves provided in the three directional control hydraulic valves are each in an energized state as in Figures 4 and 7, or when any two of the solenoid valves provided in the three directional control hydraulic valves are in an energized state as in Figures 5 and 7. However, when at least two of the solenoid valves provided in the three directional control hydraulic valves are in a non-energized state as in Figures 6 and 8, the trip valve operates to induce an emergency shutdown of the turbine. [Industrial Applicability]

[0080] According to the present invention, even if a phenomenon occurs in which some of the plurality of solenoid valves are switched due to an internal defect, the trip system is not activated and the turbine control can be maintained, and therefore the present invention has industrial applicability.

[0081] In addition, since separate maintenance or testing can be performed on only some of the solenoid valves among a plurality of solenoid valves, the present invention has industrial applicability.

[0082] Furthermore, the unification of components provides advantages in manufacturing and maintenance, and thus has industrial applicability.

[0083] In addition, the gap between the body and the seat of the directional control hydraulic valve can be eliminated, and it is possible to prevent foreign matter from entering and becoming stuck, so that the present invention has industrial applicability.

[0084] Also, the oil leakage phenomenon that progresses to the gap between the body and the seat of the directional control hydraulic valve can be minimized, so that the present invention has industrial applicability.

[0085] Furthermore, by preventing adhesion of foreign matter and oil leakage, the reliability of the directional control hydraulic valve can be improved, and therefore the present invention has industrial applicability.

[0086] In addition, even if some of the multiple solenoid valves are stuck and cannot be switched even by a trip signal, if at least two or more valves are operating, the normal trip system can operate, which has industrial applicability. [Explanation of symbols]

[0087] 110: First plunger 120: First piston 125: First elastic body 130: First Body 131: First rod member 135: First contact member 140: First sheet 180: First input port 190: First output port 210: Second piston 215: Second elastic body 220: The third piston 225: Third Elastic Body 230: Second Body 231: second rod member 235: second contact member 240: Second sheet 250: Second plunger 270: Second output port 280: Second input port 290: Third input port 1000: Directional control hydraulic valve of the present invention

Claims

1. A directional control hydraulic valve system in which any one directional control hydraulic valve is connected to at least two other directional control hydraulic valves, The directional control hydraulic valve is a first valve that controls the flow of fluid flowing in from a first input port in cooperation with a solenoid valve that can be switched on or off; a second valve connected to the first valve and configured to control the flow of the fluid flowing in from the first valve by a fluid flowing in from a second input port or a third input port; At least a portion of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port of one of the other two directional control hydraulic valves or the third input port of the other directional control hydraulic valve, a trip valve that controls an emergency stop of the hydraulic system in cooperation with the directional control hydraulic valve; The trip valve is A directional control hydraulic valve system, comprising at least three directional control hydraulic valves, which operates only when at least two of the solenoid valves in each of the directional control hydraulic valves are in a de-energized state.

2. A directional control hydraulic valve in a directional control hydraulic valve system in which any one directional control hydraulic valve is connected to at least two other directional control hydraulic valves, a first valve that controls the flow of fluid flowing in from a first input port in cooperation with a solenoid valve that can be switched on or off; a second valve connected to the first valve and configured to control the flow of the fluid flowing in from the first valve by a fluid flowing in from a second input port or a third input port; At least a portion of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port of one of the other two directional control hydraulic valves or the third input port of the other directional control hydraulic valve, The first valve includes: a first plunger that is displaced by a fluid flowing in from the first input port or by the solenoid valve; a first piston that is displaced by a fluid flowing in from the first input port or a restoring force of a first elastic body; a first body that is displaced by the first plunger and the first piston and determines the flow of fluid that flows in from the first input port in accordance with the amount of displacement; a first seat that abuts against the first body as it is displaced to determine the amount of displacement of the first body.

3. The first valve includes: a first line providing a path for fluid entering the first input port; a second line branching off from the first line and providing a path in the direction of the first plunger; a third line branching off from the first line or the second line to provide a path in the direction of the first piston.

4. The first body includes:

3. The directional control hydraulic valve according to claim 2, wherein the cross section is circular or wedge-shaped, or is poppet-shaped, so as to come into line contact with a portion of the first seat as it moves.

5. A directional control hydraulic valve in a directional control hydraulic valve system in which any one directional control hydraulic valve is connected to at least two other directional control hydraulic valves, a first valve that controls the flow of fluid flowing in from a first input port in cooperation with a solenoid valve that can be switched on or off; a second valve connected to the first valve and configured to control the flow of the fluid flowing in from the first valve by a fluid flowing in from a second input port or a third input port; At least a portion of the fluid that has passed through the first valve is discharged to a first output port and flows into the second input port of one of the other two directional control hydraulic valves or the third input port of the other directional control hydraulic valve, The second valve is a second plunger that is displaced by fluid flowing in from the first input port; a second piston that is displaced by a fluid flowing in from the second input port or a restoring force of a second elastic body; a third piston that is displaced by a fluid flowing in from the third input port or by a restoring force of a third elastic body; a second body that is displaced by at least one of the second plunger, the second piston, and the third piston and determines the flow of the fluid that flows in from the first valve in accordance with the amount of displacement; a second seat that abuts against the second body as it is displaced to determine the amount of displacement of the second body.

6. The first valve includes:

6. The directional control hydraulic valve according to claim 5, further comprising a fourth line branching off from a first line providing a path for fluid flowing in from said first input port and providing a path in the direction of said second plunger.

7. The second valve is 6. The directional control hydraulic valve of claim 5, including an eighth line providing a path for fluid entering from said second input port in the direction of said second piston.

8. The second valve is 6. The directional control hydraulic valve of claim 5, including a ninth line providing a path for fluid entering from said third input port in the direction of said third piston.

9. The second body includes:

6. The directional control hydraulic valve according to claim 5, wherein the cross section is circular or wedge-shaped, or is poppet-shaped, so as to come into line contact with a portion of the second seat as it moves.

10. 6. The directional control hydraulic valve of claim 5, further comprising a fifth line providing a path for fluid through said first valve in the direction of said first output port.

11. 11. The directional control hydraulic valve of claim 10, further comprising a sixth line branching off from the fifth line to provide a path in the direction of the second valve.

12. 6. The directional control hydraulic valve of claim 5, further comprising a seventh line providing a path for fluid through said second valve to be discharged to a second output port.

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