JP3631632B2 - Valve device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve device having a relief valve function.
[0002]
[Prior art]
Figure2Shows a meter-in / meter-out separated control circuit.22 shows a bridge-structured control circuit for controlling the single rod / cylinder type actuator 11.
[0003]
This control circuit is a pump line in which a tank 15 is connected via a common bypass valve 14 to a discharge port of a variable displacement pump 13 whose discharge flow rate can be variably controlled by a swash plate 12, and a load hold check valve 16 is provided. A bridge circuit 18 is connected via 17.
[0004]
The bridge circuit 18 is formed by two meter-in valves 21 and 22 connected to the pump line 17 and two meter-out valves 23 and 24 connected to the meter-in valves 21 and 22, respectively. Yes.
[0005]
These meter-out valves 23 and 24 are connected to the tank line 25, and each meter-out valve 23 and 24 is replenished with hydraulic oil as hydraulic fluid from the tank line 25 to the negative pressure generating part in the circuit. Makeup check valves 26 and 27 are connected in parallel.
[0006]
A passage 31 drawn from between the meter-in valve 21 and the meter-out valve 23 shown on the upper side of the bridge circuit 18 is a chamber on the side where the rod 33 is located from the piston 32 of the actuator 11 (hereinafter referred to as “rod-side chamber”). ) 34, and a passage 35 drawn from between the meter-in valve 22 and the meter-out valve 24 illustrated on the lower side is a chamber (hereinafter referred to as a head side) that is located on the head side from the piston 32 of the actuator 11. , “Head side chamber”).
[0007]
The inlet side of the meter-out valve 23 and the meter-out valve 24 is a return passage 37 from the actuator 11.
[0008]
The common bypass valve 14, meter-in valves 21, 22 and meter-out valves 23, 24 are provided with variable throttle means such as spool valves or poppet valves whose opening area can be variably controlled by electromagnetic means or pilot hydraulic means. The variable throttle means is controlled by a pilot pressure signal directly in the case of electromagnetic means, or via an electro-oil conversion means in the case of pilot hydraulic means, by an electrical signal calculated by the controller and output from the controller. .
[0009]
The hydraulic oil supplied from the pump 13 to one of the rod side chamber 34 and the head side chamber 36 of the actuator 11 and discharged from the other to the tank 15 is supplied to the two meter-in valves 21 and 22 and the two meter-out valves 23. , 24 is controlled by the bridge circuit 18 formed.
[0010]
For example, when extending the actuator 11 against the load W, the common bypass valve 14 is closed, the meter-in valve 22 on the head side of the actuator 11 is opened and the meter-out valve 24 is closed, and the meter-in on the rod side is closed. The valve 21 is closed and the meter-out valve 23 is opened.
[0011]
When contracting the actuator 11, the common bypass valve 14 is closed, the meter-in valve 21 on the rod side of the actuator 11 is opened, the meter-out valve 23 is closed, and the meter-in valve 22 on the head side is closed. Then, open the meter-out valve 24 on the head side.
[0012]
Figure3Shows details of the conventional meter-out valve 23 or 24, and in a valve chamber 41 formed in the valve body 40, a pilot flow rate amplification type poppet valve (hereinafter, this poppet valve will be referred to as a “flow amplifier poppet valve”). ) 42 is provided to be displaceable, and a return passage 37 from the actuator 11 communicates with an inlet port 43 opened in the valve chamber 41.
[0013]
The flow amplifier refined poppet valve 42 has a pilot control unit 44 formed at one end thereof, and a pilot variable slot 45 in which the area of the opening 45a changes in the axial direction in the vicinity of the pilot control unit 44 depending on the position of the flow amplifier refined poppet valve 42. Is formed.
[0014]
At the opposite end of the flow amplifier poppet valve 42, there is provided a drain flow rate control portion 47 that is formed at the outlet portion of the valve chamber 41 and can be fitted to and removed from the valve seat portion 46 communicated with the tank 15. A main flow rate control slot 48 is formed in the drain flow rate control unit 47.
[0015]
The pilot control unit 44 faces the spring chamber 49, and the flow amplifier poppet valve 42 is pressed toward the valve seat unit 46 by the coil spring 50 built in the spring chamber 49, that is, in the closing direction.
[0016]
A central core 51 for position detection is integrally provided at the center of the pilot control unit 44, and a coil 52 for position detection is disposed on the valve body 40 side, so that the displacement of a flow amplifier poppet valve 42 such as an operating transformer can be reduced. A displacement detection sensor for detection is formed.
[0017]
As means for controlling the opening degree of the flow amplifier poppet valve 42, a passage 53 and a passage 25a are disposed from the spring chamber 49 to the tank line 25, and a modulation stem 54 is interposed in the passage 53. The spring chamber 49 is drain-controlled in accordance with an electrical signal from a controller (not shown), and is proportionally controlled by a solenoid 55 against a coil spring (not shown).
[0018]
Further, an overload preventing pilot poppet valve 57 is interposed in another passages 56a and 56b drawn from the spring chamber 49 of the flow amplifier poppet valve 42 toward the tank 15.
[0019]
This pilot poppet valve 57 opens the valve seat portion 46 by drain-controlling the spring chamber 49 of the flow amplifier poppet valve 42 when an excessive load pressure is generated in the return passage 37 from the actuator 11. 58 is pressed against the valve seat 62 by a coil spring 61 provided in a spring chamber 60 in the pilot cylinder 59.
[0020]
The poppet taper portion 58 is integrally formed with a large diameter portion 64 via a neck portion 63, and this large diameter portion 64 is slidably fitted into a passage 65 communicated with the return passage 37, When the load pressure is guided to the tip circular pressure receiving surface 64a of the large-diameter portion 64 through this passage 65 and the force generated by the load pressure acting on the tip circular pressure receiving surface 64a is larger than the preload of the coil spring 61, the valve The seat portion 62 is opened.
[0021]
Further, a pilot piston 66 for adjusting the spring force of the coil spring 61 is slidably fitted in the pilot cylinder 59 and is locked by an adjusting screw 67. The pilot cylinder 59 is provided with a port 68 for supplying pilot pressure from the outside to the pilot piston 66, and an external pilot pressure signal generator is connected to the port 68.
[0022]
In this external pilot pressure signal generator, a pilot pump 69 is connected to a port 68 via a related pipe 71 having an electromagnetic proportional pressure reducing valve 70, and a pilot for setting a pump discharge pressure in a discharge pipe of the pilot pump 69 A relief valve 72 is provided.
[0023]
Next, figure3The operation of the conventional meter-out valve control device shown in FIG.
[0024]
(1) The return flow rate Q from the actuator 11 is guided to the inlet port 43 of the flow amplifier poppet valve 42, and the flow rate q therein flows into the spring chamber 49 from the opening 45 a of the pilot variable slot 45. The stroke control of the flow amplifier poppet valve 42 is achieved by the opening control of the modulation stem 54 communicating with the spring chamber 49, and the flow rate passing through this portion is represented by q in the figure.₂It is shown in Pilot flow q toward the upper pilot poppet valve 57₁Is zero when the pilot poppet valve 57 is closed, in which case q = q₂It becomes. On the other hand, the stroke control of the flow amplifier poppet valve 42 opens the main flow rate control slot 48 at the right end in the figure to control the main flow rate LQ. This main flow rate LQ is as if the pilot flow rate q in the modulation system 54₂Indicates an amplified aspect.
[0025]
(2) Next, the modulation stem 54 is closed and q₂When LQ and LQ are zero, the return pressure of the return passage 37 from the actuator 11 rises and acts on the tip circular pressure receiving surface 64a of the large diameter portion 64 provided at the tip of the pilot poppet valve 57. When the force overcomes the repulsive force of the coil spring 61, the poppet taper portion 58 opens from the valve seat portion 62, and the pilot flow q₁Begins to flow (in this case q = q₁Therefore, a differential pressure is generated in the opening 45a of the pilot variable slot 45 of the flow amplifier refined poppet valve 42, the flow amplifier refined poppet valve 42 moves to the left in the figure, the main flow rate control slot 48 opens, and the main flow rate LQ As a result, the return pressure of the return passage 37 from the actuator 11 is prevented from increasing abnormally, and the pressing force of the spring 61 acting on the pilot poppet valve 57 is divided by the pressure receiving area of the tip circular pressure receiving surface 64a. Settling with pressure value. That is, it also has a relief valve function.
[0026]
(3) The lift amount of the flow amplifier refined poppet valve 42 does not increase unless the opening gain of the pilot poppet valve 57 having the relief valve function is increased. That is, the opening degree of the pilot variable slot 45 of the flow amplifier poppet valve 42 increases, and q, q₁If the pressure does not increase appropriately, the override characteristics as a relief valve (the override pressure, which is the difference between the total pressure when the valve is fully open and the cracking pressure when the valve is open, should be small) may not be improved. In order to improve the characteristics, it is necessary to increase the diameter of the valve seat portion 62 and the diameter of the large diameter portion 64 at the tip with respect to the pilot poppet valve 57. Since the pressure receiving area of the large-diameter portion 64 must be increased as described above, the spring force of the coil spring 61 must necessarily be increased in order to set a high-pressure relief valve.
[0027]
For this reason,3As shown in Fig. 3, the spring force of the coil spring 61 is strong, so it is difficult to control the spring force of the coil spring 61 with a normal small thrust electromagnetic actuator.3In this way, the pilot piston 66 is applied with an external pilot pressure via a related piping 71 from a pilot hydraulic power source including an external pilot pump 69, an electromagnetic proportional pressure reducing valve 70, a pilot relief valve 72, etc. The thrust is controlled and the amount of compression of the coil spring 61 is controlled. Therefore, there are many related parts, resulting in a high cost.
[0028]
[Problems to be solved by the invention]
As described above, conventionally, in order to improve the override characteristics as a relief valve, the pressure setting spring has to be enlarged, and the setting pressure of a strong large spring can be changed by a small thrust electromagnetic actuator. Since the amount of spring compression is controlled by an external pilot pressure signal generator using an expensive electromagnetic proportional pressure reducing valve that cannot be controlled, there is a problem that the cost is increased.
[0029]
The present invention has been made in view of the above points, and by improving the shape of the pilot poppet valve, the pressure setting spring can be reduced in size while ensuring good override characteristics as a relief valve. It is another object of the present invention to reduce the cost by making it possible to variably control the relief valve set pressure with an inexpensive electromagnetic actuator.
[0030]
[Means for Solving the Problems]
ContractClaim1The pilot flow amplification type poppet valve provided on the meter-out side of the actuator and the stroke of the pilot flow amplification type poppet valve are controlled by controlling the pilot flow rate of the pilot flow amplification type poppet valve. The pilot modulation valve and the pilot flow amplification type poppet valve are connected in parallel with the pilot modulation valve.TapaIlot poppet valve andTheEquippedThis pilot poppet valve has a relief valve function that is detachably attached to the valve seat part, and a spring that presses the pilot poppet valve against the valve seat part, and a direction in which the pilot poppet valve opens against this spring A pressure receiving surface that receives a pilot signal pressure that is pressed against the donut, and the pressure receiving surface is formed between a large diameter portion and a small diameter portion that are fitted into the stepped hole, and has a smaller area than the area of the valve seat portion.・ Area-shaped pressure-receiving surfaceIt is a valve device.
[0031]
When the pilot poppet valve functions as a relief valve with respect to the pilot flow amplification type poppet valve whose pilot flow rate is controlled by the pilot modulation valve, the pilot signal pressure receiving surface has an area smaller than the area of the valve seat portion. The pilot poppet valve can increase its opening gain, ensure a large lift amount of the pilot flow amplification type poppet valve, and ensure a good override characteristic as a relief valve, while the pressure receiving surface of the pilot signal pressure is small, The pressure setting spring can be downsized.In particular, by reducing the difference in diameter between the large diameter part and the small diameter part, the area of the pressure receiving surface in the donut area can be made sufficiently small, so even if the pilot signal pressure becomes sufficiently high, the thrust of the pilot poppet valve Can be made sufficiently small, and the spring force for setting the relief valve pressure can be made sufficiently small, so that the spring can be sufficiently downsized.
[0032]
Claim2The invention described in claim 11In the mounted valve device, a separate small-diameter piston that is smaller in diameter than the valve seat portion of the pilot poppet valve and is in contact with the end face of the poppet valve opposite to the spring, and the opposite side to the contact side of this small-diameter piston And a pressure chamber for applying a pilot signal pressure to the pressure receiving surface.
[0033]
And since the pilot signal pressure is transmitted to the pilot poppet valve via the small diameter piston received by the small pressure receiving surface from the valve seat portion, the pilot poppet valve thrust can be reduced even if the pilot signal pressure becomes high, and the relief valve The spring force for setting the pressure can also be reduced, the spring can be reduced in size, and the pilot poppet valve and the separate small-diameter piston can be easily machined.
[0034]
Claim3The invention described in claim 1Or 2In the described valve device, the valve device includes a set pressure variable means that is installed in parallel with the spring for the pilot poppet valve and variably controls the set pressure of the relief valve function.
[0035]
The set pressure variable means installed in parallel with the spring acts directly on the pilot poppet valve without using the spring, so that it is not necessary to adjust the expansion and contraction of the spring, and the space of the spring can be saved.
[0036]
Claim4The invention described in claim 13This is a valve device in which the set pressure variable means in the described valve device is an electromagnetic actuator.
[0037]
And claim 1Or 2Since the described valve device can reduce the pressure setting spring, it is possible to set a relief valve even with an inexpensive electromagnetic actuator with a small spring force and almost a compulsory small thrust without using a conventional expensive external pilot pressure signal generator. Pressure can be variably controlled, reducing costs.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG.TheoryLight up. Figure2Are also used in the embodiment according to the present invention.
[0039]
FIG. 1 shows the internal structure of the meter-out valve 23 and the meter-out valve 24. In a valve chamber 41 formed in the valve body 40, a pilot flow rate amplification type poppet valve (hereinafter this poppet valve is referred to as “flow amplifier”). A poppet valve (hereinafter referred to as a “poppet valve”) 42 is provided in a freely displaceable manner, and the actuator 11 (see FIG.2) Return passage 37 is connected.
[0040]
The flow amplifier refined poppet valve 42 has a pilot control unit 44 formed at one end thereof, and a pilot variable slot 45 in which the area of the opening 45a changes in the axial direction in the vicinity of the pilot control unit 44 depending on the position of the flow amplifier refined poppet valve 42. Is formed.
[0041]
At the opposite end of the flow amplifier poppet valve 42, there is provided a drain flow rate control portion 47 that is formed at the outlet portion of the valve chamber 41 and is detachable with respect to the valve seat portion 46 communicated with the tank 15. A main flow rate control slot 48 is formed in the drain flow rate control unit 47.
[0042]
The pilot control unit 44 faces the spring chamber 49, and the flow amplifier poppet valve 42 is pressed toward the valve seat unit 46, that is, in the closing direction, by a coil spring 50 built in the spring chamber 49.
[0043]
A central core 51 for position detection is integrally provided at the center of the pilot control unit 44, and a coil 52 for position detection is disposed on the valve body 40 side, so that the displacement of a flow amplifier poppet valve 42 such as an operating transformer can be reduced. A displacement detection sensor for detection is formed. The displacement detection sensor is used for feedback control of the flow amplifier poppet valve 42 and monitoring of valve operation. However, this displacement detection sensor is not essential and may be omitted in some cases.
[0044]
As a means for controlling the opening degree of the flow amplifier poppet valve 42, a passage 49a, a passage 53a, a passage 53b and a passage 25a are disposed from the spring chamber 49 to the tank line 25, and a pilot modulation valve is provided in the passages 53a and 53b. A modulation stem 54 is interposed.
[0045]
The modulation stem 54 controls the drain flow rate from the spring chamber 49 of the flow amplifier refined poppet valve 42 according to an electrical signal from a controller (not shown), that is, by controlling the pilot flow rate of the flow amplifier refined poppet valve 42. The control valve portion 54a provided at one end of the modulation stem 54 is provided with respect to the spring receiving plate 54b locked at the other end. The push-type solenoid 55a, which is pressed in the closing direction by the coil spring 54c and receives an electric signal from the controller, pushes out the push rod 55b in response to the electric signal, so that the control valve portion 54a changes to an electric signal (energization amount). Proportionally controlled to the corresponding opening.
[0046]
Further, a passage 56a, a passage 56b, and a passage 25a branched from the passage 49a from the spring chamber 49 to the tank line 25 of the flow amplifier rippoppet valve 42 are disposed, and relief valves for preventing overload are provided in the passages 56a and 56b. A functioning pilot poppet valve 57 is interposed.
[0047]
That is, a pilot poppet valve 57 is connected to the spring chamber 49 of the flow amplifier poppet valve 42 in parallel with the modulation stem 54.
[0048]
This pilot poppet valve 57 opens the valve seat portion 46 by drain-controlling the spring chamber 49 of the flow amplifier poppet valve 42 when an excessive load pressure is generated in the return passage 37 from the actuator 11. 58 is pressed against the detachable valve seat 62 by a coil spring 61 as a spring provided in a spring chamber 60 formed in the valve body 40.
[0049]
The poppet taper portion 58 is integrally formed with a large-diameter portion 64 via a neck portion 63, and a small-diameter portion 82 is stepped into the large-diameter portion 64 via a donut-area-shaped pressure receiving surface 81. Is formed. The large diameter portion 64 and the small diameter portion 82 are slidably fitted into the stepped holes.
[0050]
The diameter of the valve seat portion 62 and the large diameter portion 64 is an override characteristic as a relief valve of the pilot poppet valve 57 (the override pressure, which is the difference between the full pressure when the valve is fully opened and the cracking pressure when the valve is open, is small) However, the donut area-shaped pressure-receiving surface 81 has a conventional tip-shaped circular pressure-receiving surface 64a (see FIG.3) It has a smaller area and an area smaller than the area of the valve seat 62. The area of the valve seat portion 62 is an area of a circle having the same diameter as the diameter of the inner space of the valve seat portion 62.
[0051]
The donut area-shaped pressure receiving surface 81 faces a pressure chamber 83 formed in the valve body 40 for applying a pilot signal pressure, and the pressure chamber 83 communicates with the valve chamber 41 through a passage 65. The valve chamber 41 communicates with a return passage 37 from the actuator.
[0052]
Therefore, the load pressure from the actuator 11 is guided to the donut-area pressure receiving surface 81 through the passage 65, and becomes a pilot signal pressure that presses the pilot poppet valve 57 in the opening direction against the coil spring 61.
[0053]
On the other hand, the chamber 84 where the distal end surface of the small diameter portion 82 faces communicates with the passage 56b through a passage 85, and further communicates with the tank line 25 through the passage 25a.
[0054]
The coil spring 61 that presses the pilot poppet valve 57 in the closing direction is locked at a fixed position by a solenoid mounting portion 86 fixed to the valve body 40. Further, an electromagnetic actuator 87 as a set pressure variable means for the pilot poppet valve 57 is provided on the solenoid mounting portion 86.
[0055]
This electromagnetic actuator 87 is provided with a small push-type solenoid 88 in a solenoid mounting portion 86, and the tip of a push rod 89 operated by this push-type solenoid 88 is in contact with the end face of the pilot poppet valve 57. .
[0056]
That is, the push rod 89 of the electromagnetic actuator 87 is in direct contact with the pilot poppet valve 57 similarly to the coil spring 61, and the coil spring 61 and the electromagnetic actuator 87 act in parallel with the pilot poppet valve 57. It is configured.
[0057]
in this way,
(1) The opening control mechanism by the modulation stem 54 for controlling the stroke of the flow amplifier poppet valve 42 is illustrated in FIG.3However, the structure of the pilot poppet valve 57 that functions as a relief valve to determine the set pressure is different.
[0058]
(2) The pilot poppet valve 57 has a pilot flow rate q to improve the override characteristics as a relief valve.₁Has a considerably large valve seat diameter. However, the pressure receiving area portion that senses the return pressure of the return passage 37 from the actuator 11 is a donut area-shaped pressure receiving surface 81 between the large diameter portion 64 and the small diameter portion 82 fitted in the stepped hole, and the large diameter portion The difference in diameter between the small diameter portion 64 and the small diameter portion 82 is reduced to sufficiently reduce the area of the pressure receiving surface 81.
[0059]
(3) With the above structure, even if the return pressure from the actuator 11 in the return passage 37 becomes high, the thrust applied to the pilot poppet valve 57 can be small. Therefore, the coil spring 61 can be reduced in size, and a small electromagnetic actuator 87 having a level comparable to the spring force and its maximum thrust can be installed in parallel with the coil spring 61 as a means for changing the set pressure.
[0060]
Next, the function and effect of the embodiment shown in FIG. 1 will be described.
[0061]
(1) Since the diameter of the valve seat portion 62 of the pilot poppet valve 57 can be increased, the opening gain of the pilot poppet valve 57 can be increased, and a good override characteristic as a relief valve of the flow amplifier poppet valve 42 can be secured.
[0062]
(2) A stepped large-diameter portion 64 and a small-diameter portion 82 are formed at the tip of the pilot poppet valve 57, and the pressure-receiving surface is formed by a difference in cross-sectional area between the large-diameter portion 64 and the small-diameter portion 82, that is, a donut area. Since the area of 81 is reduced, the spring force for setting the relief valve pressure can be reduced, and the coil spring 61 can be reduced in size.
[0063]
(3) In order to variably control the set pressure as the relief valve, a small and inexpensive electromagnetic actuator 87 having a level comparable to the spring force of the coil spring 61 and the maximum thrust force can be reduced. Therefore, it can be incorporated in parallel with the coil spring 61.
[0064]
(4) As in the past, parts such as the pilot piston 66 for variable control of the relief valve set pressure, the external pilot pump 69, the electromagnetic proportional pressure reducing valve 70 and the pilot relief valve 72, and the related piping 71 are not required, and low Cost can be increased.
[0065]
Less thanAs described above, the override related to the cracking pressure set in the pilot poppet valve 57 having the relief valve function provided for the spring chamber 49 of the pilot flow rate amplification type poppet valve installed in the return passage 37 from the actuator 11 This is a technology for improving the characteristics. The structure of the pilot poppet valve 57 for determining the set pressure with a relief valve function has been changed, and the pressure receiving surface for the return pressure from the actuator 11 is changed to the pressure receiving surface in a small donut area. The coil spring 61 can be reduced in size by replacing the pressure receiving surface 81 of the donut area with the pressure receiving surface 93 of the small piston 91.
[0066]
Further, as a setting pressure variable means of the pilot poppet valve 57, it is only necessary to install a small and inexpensive push type electromagnetic actuator 87, and the conventional pilot piston 66, pilot pump 69, electromagnetic proportional pressure reducing valve 70, pilot Expensive facilities such as the relief valve 72 and related piping 71 are not required, and the cost can be reduced.
[0067]
The valve device of the present invention is particularly suitable as a relief valve for a pilot flow rate amplification type poppet valve used for actuator meter-out control of construction machinery. Is also widely applicable.
[0068]
【The invention's effect】
ContractClaim1According to the described invention, when the pilot poppet valve functions as a relief valve with respect to the pilot flow rate amplification type poppet valve whose pilot flow rate is controlled by the pilot modulation valve, the pilot signal pressure having an area smaller than the area of the valve seat portion. The pilot poppet valve with the pressure receiving surface can increase the opening gain, ensure a large lift amount of the pilot flow amplification type poppet valve, and receive the pilot signal pressure while ensuring good override characteristics as a relief valve Since the surface is small, the pressure setting spring can be miniaturized.In particular, by reducing the difference in diameter between the large diameter part and the small diameter part, the area of the pressure receiving surface in the donut area can be made sufficiently small, so even if the pilot signal pressure becomes sufficiently high, the thrust of the pilot poppet valve Can be made sufficiently small, and the spring force for setting the relief valve pressure can be made sufficiently small, so that the spring can be sufficiently downsized.
[0069]
Claim2According to the described invention, since the pilot signal pressure is transmitted to the pilot poppet valve through the small diameter piston received by the pressure receiving surface having a smaller diameter than the valve seat portion, even if the pilot signal pressure becomes high, the thrust of the pilot poppet valve is transmitted. The spring force for setting the relief valve pressure can be reduced, the size of the spring can be reduced, and the pilot poppet valve and the separate small-diameter piston can be easily machined.
[0070]
Claim3According to the described invention, the set pressure variable means for variably controlling the set pressure of the relief valve function installed in parallel with the spring acts directly on the pilot poppet valve without using the spring. No space is required for the spring.
[0071]
Claim4According to the described invention, the pressure setting spring can be reduced in size.ValveSince the set pressure variable means is an electromagnetic actuator in the device, the relief valve set pressure can be achieved even with a small and inexpensive electromagnetic actuator that is almost compatible with the small spring force without using a conventional expensive external pilot pressure signal generator. Can be variably controlled, and cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a valve device according to the present invention.
FIG. 2 is a circuit diagram showing a meter-in / meter-out separate control circuit;
FIG. 3 is a cross-sectional view showing a conventional valve device.
[Explanation of symbols]
11 Actuator
42 Pilot flow amplification type poppet valve (flow amplifier poppet valve)
54 Modulation stem as pilot modulation valve
57 Pilot poppet valve
61 Spring
62 Valve seat
64 Large diameter part
81 Donut area-shaped pressure-receiving surface
82 Small diameter part
83 Pressure chamber
87 Electromagnetic actuator as variable pressure setting
91 Small diameter piston
93 Pressure sensing surface

Claims (4)

A pilot flow rate amplification type poppet valve provided on the meter-out side of the actuator;
A pilot modulation valve that controls the stroke of the pilot flow rate amplification type poppet valve by controlling the pilot flow rate of the pilot flow rate amplification type poppet valve;
; And a path for the pilot poppet valve connected in parallel with the pilot modulation valve to the pilot flow amplification type poppet valve,
This pilot poppet valve has a relief valve function that is detachably attached to the valve seat.
A spring that presses the pilot poppet valve against the valve seat,
A pressure receiving surface that receives a pilot signal pressure that presses the pilot poppet valve in the opening direction against the spring;
The pressure receiving surface is a donut area-shaped pressure receiving surface formed between a large diameter portion and a small diameter portion fitted in a stepped hole and having an area smaller than the area of the valve seat portion. Characteristic valve device. A separate small-diameter piston that is smaller in diameter than the valve seat portion of the pilot poppet valve and is in contact with the end face of the poppet valve opposite to the spring;
A pressure receiving surface provided on an end surface opposite to the contact side of the small diameter piston,
The pressure receiving surface claim 1 Symbol mounting of the valve device, characterized by comprising a pressure chamber for applying a pilot signal pressure to. 3. A valve device according to claim 1, further comprising a set pressure variable means for variably controlling the set pressure of the relief valve function, which is installed in parallel with the spring for the pilot poppet valve. 4. The valve device according to claim 3, wherein the set pressure varying means is an electromagnetic actuator.

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