JPH0433048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a pressure reducing valve consisting of a main valve and a pilot valve.

<Prior art> Conventionally, this type of pressure reducing valve is known as one consisting of a main valve 1 and a povet type two-port pilot valve 2, as shown in Fig. 10 (Hydraulic Technology, Vol. 24). No. 4 page 21). This pressure reducing valve is connected from the secondary port B side of the main valve 1 to the poppet 3 of the pilot valve 2.
A pilot passage 6 having a vent throttle 5 forming a vent flow to the main valve 1 is provided, and the fluid pressure between the vent throttle 5 and the poppet 3 is guided to a spring chamber 8 at one end side of the main spool 7 of the main valve 1. The pressure at the secondary port B of the main valve 1 is guided to the pilot chamber 9 at the other end of the main spool 7. In other words, the fluid pressure in the pilot chamber 9 and the resultant force obtained by adding the force of the spring 10 to the fluid pressure in the spring chamber 8 are opposed to the main spool 7, and the fluid pressure in the secondary port B is the setting of the pilot valve 2. When pressure is reached, pilot valve 2 opens to create a vent flow. Therefore, a pressure difference is formed before and after the vent throttle 5, and when this pressure difference becomes equivalent to spring pressure, the main spool 7 is operated to narrow the opening degree of the variable orifice 4 and reduce the pressure at the secondary port B. . When the fluid pressure at the secondary port B becomes lower than the set pressure, the pilot valve 2 closes and the vent flow rate is reduced to zero, so the differential pressure before and after the vent throttle 5 is eliminated, and the force of the spring 10 closes the main spool. 7 is moved to the right in FIG. 3 to widen the opening degree of the variable orifice 4 and supply fluid from the primary port A to the secondary port B. Also, a relief operation is performed from the secondary port B to the tank port T.

<Problems to be Solved by the Invention> By the way, in the above-mentioned conventional pressure reducing valve, when the pressure at the secondary port B falls below the set pressure during the pressure reducing operation, especially when the pressure at the secondary port B falls below the set pressure, When the pressure decreases rapidly enough to completely close the pilot valve 2, the pressure at the secondary port B is reduced only after the poppet valve 3 is closed and the main spool 7 is moved to the right and opened. Rise.
However, in this structure in which the main spool 7 of the main valve 21 is operated following the pilot valve 2 to control the pressure of the secondary port B for the first time, the mass and dimensions of the main spool 7 are large; Secondary port B due to slow operation due to load
There is a problem in that the response of the correction operation to pressure fluctuations is poor.

Therefore, an object of the present invention is to enable fluid to be actively supplied from the pilot valve to the secondary port of the main valve prior to the operation of the main valve, thereby improving the response of pressure control of the pressure reducing valve to fluctuations on the load side. The aim is to enhance sexuality.

<Means for Solving the Problems> In order to solve the above problems, the present invention provides a spool-type three-port main valve 21 and a pilot valve 22, as illustrated in FIGS. 1, 5, and 9. The pilot valve 22 is connected to the primary port A of the main valve 21.
Connect the primary port a of the pilot valve 22 to the secondary port B of the main valve 21, and
The basic feature is that the main valve 21 and the pilot valve 22 are connected in parallel. For more details, see 2.
One end side of the main spool 25 that switches and communicates the secondary port B with the primary port A and the tank port T is connected to the secondary port B via a passage, and the other end side of the main spool 25 is connected to the passage having a throttle 33. The main valve 21 communicates with the secondary port B through the passageway, and the pilot spool 41 connects the secondary port B to the primary port a and the tank port T via a passage. b, and adjustable pressing means 4 on the other end side of the pilot spool 41.
The primary port a of the pilot valve 22 is connected to the primary port A of the main valve 21, and the secondary port b of the pilot valve 22 is connected to the main spool 25. It is characterized by communicating with the other end.

<Function> During normal pressure reduction operation, if the secondary pressure P _B of the secondary port B of the main valve 21 suddenly drops below the set pressure for some reason, one end side of the pilot spool 41 of the pilot valve 22 The pressure of
The pilot spool 41 operates to open the space between the primary port a and the secondary port b and close the space between the secondary port b and the tank port t. from the secondary port b of the main valve 21 through the throttle 33
A compensating flow is generated to supply the secondary port B
Fluid is supplied from the pilot valve 22, and then the main valve 21 is operated to increase the opening degree of the variable orifice 26, increasing the main flow. in this way,
Before the main valve 21 operates, the primary port a is actively
Since pressure fluid is supplied from the main valve 21 to the other end side of the main spool 25 and the secondary port B, the main valve 21
The responsiveness of the corrective action to pressure fluctuations at the secondary port B becomes faster. In addition, since pressure fluid is supplied to the other end of the main spool 25 through the pilot valve 22 in this way, the main spool 25 resists the axial thrust (flow force) acting on the main spool 25.
can be operated quickly, and therefore can resist large axial thrusts, increasing the maximum flow rate.

Next, for some reason, the secondary port B of the main valve 21
Suppose that the secondary pressure P _B suddenly rises above the set pressure. Then, the pressure at one end of the pilot spool 41 of the pilot valve 22 increases, and the pilot spool 41 operates to open between the secondary port b and the tank port t, increasing the pilot flow as drain. Main valve 21 also here
Prior to the closing operation, the pilot valve 22 operates to reduce the pressure P _B at the secondary port B of the main valve 21, and then the main valve 21 closes to reduce the main flow. Furthermore, the secondary port B and the tank port T are communicated with each other to perform a depressurizing action. In this way, the pilot valve 22 directly performs the pressure reducing action before the main valve 21, resulting in faster response.

<Examples> The present invention will be described in detail below with reference to illustrated examples.

In Fig. 1, 21 is a 3-port main valve;
2 is a 3-port pilot valve.

The main valve 21 switches the secondary port B to the primary port A and the tank port T at lands 25a and 25b by operating the main spool 25. A secondary port B is connected to the pilot chamber 28 at one end of the main spool 25 through a pilot passage 29, and a throttle 33 is connected to the spring chamber 32 at the other end of the main spool 25 in which the spring 31 is compressed.
The secondary port B is connected through a pilot passage 35 having a diameter. Therefore, the main valve 21 operates the main spool 25 so that the differential pressure between the pilot chamber 28 and the spring chamber 32 corresponds to the spring force of the spring 31, and controls the secondary port B, the primary port A, and the tank port. The opening degree of variable orifices 26 and 30 between T and T is controlled.

On the other hand, the pilot valve 22 switches the secondary port b to the primary port a and the tank port t at the land 41a by operating the pilot spool 41. A secondary port b is connected to the chamber 45 at one end of the pilot spool 41 via a pilot passage 46. The pilot valve 22 is equipped with a spring 47 having a weak spring force for determining the rest position of the pilot spool 41. On the other hand, the pilot spool 4
An electromagnetic proportional solenoid 48 as an example of adjustable pressing means is provided on the other end side of the pilot spool 41.
The plunger 48a presses with a force proportional to the current energization value i. Therefore, the pilot spool 41 of the pilot valve 22
operates so that the pressing force of the plunger 48a and the pressure in the chamber 45, that is, the pressure at the secondary port b, are balanced.

The primary port a of the pilot valve 22 is connected to the primary port A of the main valve 21 via a pilot passage 51, and the secondary port b of the pilot valve 22 is connected to a spring port connected to the secondary port B of the main valve 21. It is connected to the chamber 32 via a pilot passage 52, so that the main valve 21 and the pilot valve 22 are connected in parallel. A tank port t of the pilot valve 22 is connected to a tank 54 via a drain passage 53.

Further, the secondary port B of the main valve 21 is connected to the hydraulic cylinder 55 via a passage 56, the primary port A is connected to the pressure source 57 via a passage 58, and the tank port T is connected to the tank 61. ing.

In the above configuration, the current value i flowing to the electromagnetic proportional solenoid 48 is constant, and the hydraulic cylinder 5
5 is at rest under the influence of the load, and the main valve 21
from secondary port B to throttle 33 and pilot valve 22
It is assumed that a vent flow to the tank 54 occurs through the secondary port b and the tank port t, and a pressure difference corresponding to the spring pressure of the spring 31 of the main valve 21 is generated before and after the throttle 33.

Now, for some reason, the secondary port B of the main valve 21
Suppose that the fluid pressure P _B suddenly drops below the set pressure (equilibrium point). Then, the pilot chamber 45 of the pilot valve 22 communicating with the secondary port B
The pressure of the pilot spool 41 also decreased rapidly.
is pressed by the electromagnetic proportional solenoid 48 and moves downward in FIG. 1, supplying pressure fluid from the primary port a to the secondary port b of the pilot valve 22.
The pressure on the secondary port b side of the pilot valve 22 increases prior to the operation of the main valve 21. Therefore, the vent flow rate passing through the throttle 33 decreases, or
3 flows from the secondary port b side of the pilot valve 22 to the secondary port B of the main valve 21. Subsequently, the main spool 25 of the main valve 21 is moved by the pressure on the secondary port b side of the pilot valve 22 acting on the spring chamber 31 and the spring pressure of the spring 31.
5 moves to the left in FIG.
6 is increased to increase the main flow from primary port A to secondary port B.

In this way, before the main valve 21 opens, the pilot valve 2, which is smaller and faster in response than the main valve 21, is opened.
Since the pressure fluid is supplied to the spring chamber 32 and the secondary port B of the main valve 21 through the main valve 2, the response of the correction operation to pressure fluctuations in the secondary port B of the main valve 21 due to the influence of load becomes faster.

Further, when the main spool 25 of the main valve 21 operates to close the variable orifice 26 due to the axial thrust and the pressure in the secondary port B decreases, the main valve 21
As mentioned above, the pilot valve 22 is installed in the spring chamber 32 of 1.
Since pressure fluid is supplied through the spring chamber 32
The spring force of the spring 31 becomes stronger apparently, and the main spool 25 can be opened against the axial thrust, and the valve 21
The maximum flow rate can be increased.

Next, for some reason, the secondary port B of the main valve 21
Suppose that the pressure P _B suddenly rises above the set pressure. Then, the pressure in the pilot chamber 45 at one end of the pilot spool 41 of the pilot valve 22 increases, and the pilot spool 41 moves upward in FIG. 1 to open the space between the secondary port b and the tank port t. operates to further increase vent flow as drain. Here too, the pilot valve 22 operates prior to the closing operation of the main valve 21 to reduce the pressure P _B at the secondary port B of the main valve 21, and then the main valve 21 closes the secondary port B. The space between the primary ports A is narrowed, and a flow is caused from the secondary port B to the tank port T, thereby performing a depressurizing effect. In this way, the pilot valve 22 directly performs the pressure reducing action before the main valve 21, so that the responsiveness of the corrective action to pressure fluctuations at the secondary port B becomes faster.

FIG. 2 is a graph showing the relationship between the current value i energized to the electromagnetic proportional solenoid 48 of the pilot valve 22 and the fluid pressure P _B of the secondary port B of the main valve 21, and FIG. A graph showing the relationship between the sum of the flow rate Q _T from the tank port T of the valve 21 and the flow rate Q _T from the tank port t of the pilot valve 22. Figure 4 shows the primary pressure when the current value i is constant. It is a graph showing the relationship between PA and secondary pressure P _B.

Although not shown, if a dither effect is added to the pilot spool 41 of the pilot valve 22,
More accurate proportional pressure control is possible.

FIG. 5 shows another embodiment in which the spring 3 of the main valve 21
1 is inverted compared to the one shown in FIG. 1, and the spring 31 is compressed in the pilot chamber 28 at one end of the main spool 25. The other configurations are the same as those shown in FIG. 1, so the same reference numerals are given to them and the explanation will be omitted.

In the case shown in FIG. 5, when the pressure P _B of the secondary port B of the main valve 21 is the set pressure (at equilibrium), the throttle 3
The pilot flow flowing through the main valve 2 from the secondary port b of the pilot valve 22 is opposite to that in FIG.
1 flows toward the primary port B of No. 1. 6th, 7th, 8th
The figures are graphs corresponding to figures 2, 3 and 4 of the previous embodiment, respectively.

The embodiment shown in FIG. 9 is one of the embodiments shown in FIG.
The main spool 25 is modified in shape by replacing the next port A and the tank port T, and the other configuration is the same as that shown in FIG.

<Effects of the Invention> As is clear from the above, the present invention provides a method for connecting the primary port of the main valve to the primary port of a spool-type three-port pilot valve, and connecting the primary port of the main valve to the secondary port of the pilot valve. The secondary port and the other end of the main spool are connected, and the main valve and pilot valve are connected in parallel, so if the pressure at the secondary port of the main valve fluctuates due to the influence of load, the main valve Prior to operation, pressure fluid can be actively supplied from the pilot valve to the secondary port of the main valve, making it possible to correct the pressure reducing valve in response to pressure fluctuations at the secondary port of the main valve due to the influence of load, etc. The response of the operation can be made faster, and the main spool of the main valve can be connected to the second valve of the pilot valve.
Since it can be operated with fluid supplied from the next port, there is no closing phenomenon of the variable orifice due to the axial thrust of the main spool, and it can operate normally even under large axial thrust, increasing the maximum flow rate of the pressure reducing valve.

[Brief explanation of drawings]

1, 5, and 9 are principle diagrams of one embodiment of the present invention, and FIGS. 2, 3, 4, and 6 respectively.
, FIG. 7, and FIG. 8 are characteristic diagrams of the above embodiment, respectively.
FIG. 10 is a sectional view of a conventional example. 21... Main valve, 22... Pilot valve, 25... Main spool, 33... Throttle, 41... Pilot spool, 48... Electromagnetic proportional solenoid.

Claims (1)

[Claims] 1. One end side of the main spool 25 that switches and communicates the secondary port B with the primary port A and the tank port T is connected to the secondary port B via a passage, and the other end of the main spool 25 is connected to the secondary port B via a passage. The main valve 21 is connected to the secondary port B through a passage having a throttle 33 on its side, and the secondary port B is connected to the primary port a and the tank port t.
A three-port pilot valve 2 having one end side of a pilot spool 41 communicating with the secondary port b via a passage, and an adjustable pressing means 48 provided on the other end side of the pilot spool 41.
2, the primary port a of the pilot valve 22 communicates with the primary port A of the main valve 21, and the secondary port b of the pilot valve 22 communicates with the other end of the main spool 25. A pressure reducing valve characterized by: