JPS61285513A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To improve the responsiveness of the pressure control of a pressure reducing valve against the fluctuation of the load, by supplying positively a fluid to the operation of the main valve. CONSTITUTION:A 3-port type main valve 21 of a spool style is provided together with a pilot valve 22. The primary port (a) of the valve 22 is connected the primary port A of the valve 21. While the secondary port (b) of the valve 22 is connected to the secondary port B of the valve 21 respectively. When the secondary pressure PB of the port B drops suddenly less than a set level, a pressure fluid is supplied positively to the end at the other side of a main spool 25 of the valve 21 as well as the port B from the port (a) through the compact valve 22 having the high responsiveness before the valve 21 works.

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, as shown in Fig. 1O, this type of pressure reducing valve consists of a main valve (1) and a poppet type two-bottom pilot valve (
2) is known (Hydraulic Technology, Vol. 24 N
o, 4 p. 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 passageway (6) having a vent restriction (5) forming a vent flow to the main spool (7) of the main valve (1) is provided, and the fluid pressure between the vent restriction (5) and the poppet (3) is transferred to the main spool (7) of the main valve (1). ) into the spring chamber (8) on one end side, while the main valve (1
) is guided to the pilot chamber (9) at the other end of the main spool (7). In other words, the main spool (7) is opposed by 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), and the secondary port ( When the fluid pressure in B) reaches the set pressure of the pilot valve (2), the pilot valve (2) opens to form 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 adjust the opening degree of the variable orifice (4), and the secondary port ( The pressure of B) is reduced. When the fluid pressure at the secondary port (B) becomes lower than the set pressure, the pilot valve (2) closes and reduces the vent flow rate to zero, so the vent throttle (5)
The differential pressure before and after is eliminated, and the main spool (7) is moved to the right in Fig. 3 by the force of the spring (lO), widening the opening of the variable orifice (4) and allowing the flow to flow from the primary port (A). It supplies fluid to the secondary port (B). In addition, 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, ) (B) drops rapidly enough to completely close the pilot valve (2), after the poppet valve (3) closes, move the main spool (7) to the right to perform the opening operation. Only then does the pressure at the secondary port (B) rise. However, in this structure where 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 main spool (7) Since the main spool (7) is large in mass and size, and the movement of the main spool (7) is slow, there is a problem in that the responsiveness of the correction operation to pressure fluctuations at the secondary port (B) due to the influence of load is poor.

Therefore, an object of the present invention is to enable fluid to be actively supplied from a pilot valve to a secondary port of the main valve prior to the operation of the main valve, so that the pressure control of the pressure reducing valve responds 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 has the following features:
As illustrated in the figure, a spool-type 3-port main valve (21) and a pilot valve (22) are used, and the main valve (21)
Connect the primary port (a) of the pilot valve (22) to the primary port (A) of the main valve (2), and connect the secondary port (b) of the pilot valve (22) to the secondary port (B) of the main valve (2■). The basic feature is that the main valve (21) and the pilot valve (22) are connected in parallel. More specifically, one end side of the main spool (25) which switches the secondary port (B) to communicate with the primary port (A) and the tank port (T) is connected to the secondary port (B) via a passage, A main valve (21) in which the other end side of the main spool (25) is connected to the secondary port (B) through a passage having a throttle (33), and the secondary port (b) is connected to the primary port. (a) and the tank port (t), one end side of the pilot spool (41) is connected to the secondary port (b) through a passage, and the other end side of the pilot spool (41) is adjusted. Possible pressing means (
48), the primary port (a) of the pilot valve (22) is connected to the primary port (A) of the main valve (2I), and the pilot valve (22) is connected to the primary port (A) of the main valve (2I). The secondary port (b) of (22) is connected to the other end of the main spool (25). If the secondary pressure (PB) of the secondary port (B) of (21) suddenly drops below the set pressure, the pressure at one end of the pilot spool (41) of the pilot valve (22) will drop, The pilot spool (41) operates to open between the primary port (a) and the secondary port (b) and close between the secondary port (b) and the tank port (t), thereby opening the main valve. Prior to the operation of (21), the secondary port (
A compensation flow is generated from b) through the throttle (33) to be supplied to the secondary port (B) of the main valve (21), and fluid is supplied from the pilot valve (22) to the secondary port (B). Then, the main valve (2I) operates to open the variable orifice (26).
The main flow increases as the opening degree increases. In this way, before the main valve (21) operates, pressure fluid is actively supplied from the primary port (a) to the main spool (2I) of the main valve (2I) through the small and quick-response pilot valve (22). 25) to the other end side and the secondary port (B).
1) The responsiveness of the corrective action to pressure fluctuations at the secondary port (B) becomes faster. Also, like this, the pilot valve (2
Since pressure fluid is supplied to the other end of the main spool (25) through 2), the axial thrust (
The main spool (25) can be actuated quickly against the flow force (flow force), and therefore can resist even a large axial thrust and increase the maximum flow rate.

Next, for some reason, the secondary port (B) of the main valve (21)
Suppose that the secondary pressure (PB) 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 (4I) moves between the secondary port (b) and the tank port (
1) to increase the pilot flow as a drain.

Here too, the pilot valve (22) operates prior to the closing operation of the main valve (21), and the secondary port (B) of the main valve (21)
The pressure (PB) of
The tank port (T) is communicated with the tank port (T) 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.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

In FIG. 1, 21 is a 3-port main valve, and 22 is a 3-port pilot valve.

The main valve (21) is connected to the secondary port (B) at the lands (25a) and (25b) by the operation of the main spool (25).
The primary port (A) and the tank port (T) are switched to communicate with each other. A secondary port (B) is connected to the pilot chamber (28) at one end of the main spool (25) via a pilot passage (29), and a spring (31) at the other end of the main spool (25) is connected to the pilot chamber (28) at one end of the main spool (25). Spring chamber (3)
2) has a pilot passage (35) with a throttle (33);
The secondary port (B) is connected via the.

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 the secondary port
- (B) and on the primary port (A) and on the tank port (T)
The opening degrees of the variable orifices (26) and (30) between the two are 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). . Above pilot spool (
A pilot passage (46) is provided in the chamber (45) at one end of 41).
) is connected to the secondary port (b). A spring (47) with a weak spring force is attached to the pilot valve (22) to determine the rest position of the pilot spool (4I).
It is reduced in size. On the other hand, the above pilot spool (4■
) is provided with an electromagnetic proportional solenoid (48) as an example of adjustable pressing means, and the center of the pilot spool (4) is controlled by the plunger (48a) of the electromagnetic proportional solenoid (48). It is pressed with a force proportional to the energization value (i). Therefore, the pilot spool (41) of the pilot valve (22) has the pressing force of the plunger (4111a) and the pressure of the chamber (45), that is, 2
It operates so that the pressure at the next port (b) is balanced.

The primary port (a) of the pilot valve (22) is connected to the primary port (a) of the main valve (21) via the pilot passage (51).
A), and also connects to 2 of the pilot valve (22).
The secondary port (b) is connected to the spring chamber (32) communicating with the secondary port (B) of the main valve (21) via the pilot passage (52), and the main valve (21) and the pilot valve (22) are connected to each other via the pilot passage (52). connected in parallel. The tank port (t) of the pilot valve (22) is connected to the 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), and the primary port (A) is connected to the pressure source (57) through a passage (58). The tank port (T) is connected to the tank (61).

In the above configuration, the current value (i) flowing to the electromagnetic proportional solenoid (48) is constant, and the hydraulic flick (55)
is stationary due to the influence of the load, and 2 of the main valve (21)
From the next port (B) to the throttle (33) and the pilot valve (22
) through the secondary port (b) and tank port (t) to the tank (54), and the above-mentioned restrictor (
It is assumed that a pressure difference corresponding to the spring pressure of the spring (31) of the main valve (21) occurs before and after the main valve (21).

Now, for some reason, the secondary port (B) of the main valve (21)
Suppose that the fluid pressure (Pa) of is suddenly lower than the set pressure (equilibrium point). Then, the pressure in the pilot chamber (45) of the pilot valve (22) that communicates with the secondary port (B) also drops rapidly, and the pilot spool (41) is pressed by the electromagnetic proportional solenoid (48), as shown in Figure 1. Since the pressure fluid is moved downward and supplied from the primary port (a) of the pilot valve (22) to the secondary port (b), the pressure on the secondary port (b) side of the pilot valve (22) is the main pressure. Valve (2
It rises prior to operation 1). Therefore, the aperture (33
) is reduced, or the throttle (33) is moved from the secondary port (b) side of the pilot valve (22) to the main valve (
A backflow occurs which flows to the secondary port (B) of 2I). Next, the main spool (25) of the main valve (21) is connected to the spring chamber (3).
The secondary port (1) of the pilot valve (22) that acts on
1) side and the spring pressure of the spring (31), the main spool (25) moves to the left in Fig. 1, increases the opening degree of the variable orifice (26), and opens the primary port (A). to the secondary port (B).

In this way, the main valve (21) is opened before the main valve (21) is opened.
A pilot valve (22) that is smaller and has faster response than 1).
Through this, pressure fluid is supplied to the spring chamber (32) and the secondary port (B) of the main valve (21), so it is possible to correct the pressure fluctuations in the secondary port (B) of the main valve (21) due to the influence of load. responsiveness 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 of the secondary port (B) decreases, the main spool (25) of the main valve (21)
) in the spring chamber (32) of the pilot valve (22) as described above.
) is supplied with pressure fluid through the spring chamber (32).
The spring force of the spring (31) becomes apparently stronger, and the main spool (25) can be opened against the axial thrust, opening 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 (PB) 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 connect to the secondary port (b). It operates to open the space between the tank port (t) and further increases the vent flow rate as a drain. Here too, the pilot valve (22) operates prior to the closing operation of the main valve (21) to reduce the pressure (Pa) of the secondary port (B) of the main valve (2I), and then,
The main valve (21) narrows the gap between the secondary port (B) and the primary port (A), and also creates a flow from the secondary port (B) to the tank port (T) to reduce pressure. Let's do it. In this way, the pilot valve (22) directly performs the pressure reducing action before the main valve (21), so that the responsiveness of the correction operation to pressure fluctuations at the secondary port (B) becomes faster.

Figure 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 (Pa) of the secondary port (B) of the main valve (21). , Figure 3 shows the flow ff1 (Qr) from the tank port (T) of the main valve (21) and the flow fi (Qt) from the tank port (t) of the pilot valve (22) for the above current value (i).
FIG. 4 is a graph showing the relationship between the original primary pressure (PA) and the secondary pressure (PB) at a constant current value (i).

Although not shown, if a dither effect is added to the pilot spool (41) of the pilot valve (22), more accurate proportional pressure control can be achieved.

FIG. 5 shows another embodiment, in which the spring (3I) of the main valve (2I)
) is inverted compared to the one shown in FIG. 1, and the spring (31) is compressed into 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 device shown in Fig. 5, when the pressure (PB) of the secondary port (B) of the main valve (21) is at the set pressure (at equilibrium), the throttle (
The pilot flow flowing through the main valve (33) is opposite to that in Figure 1, and flows from the secondary port (b) of the pilot valve (22) to the main valve (
21) to the primary port (B).

6.7.8 are graphs that each correspond to FIG. 2.3.4 of the previous example.

The embodiment shown in FIG. 9 is a modification of the main spool (25) by replacing the primary port (A) and tank port (T) of the embodiment shown in FIG. It is similar to that shown in FIG.

<Effects of the Invention> As is clear from the above, the present invention provides the primary port of the main valve to be connected to the primary port of a spool-type 3-port pilot valve, and the secondary 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 respectively, 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 Pressure fluid can be actively supplied from the pilot valve to the secondary port of the main valve prior to the operation of the pressure reducing valve, so that the pressure reducing valve can correct the pressure fluctuations at the secondary port of the main valve due to the influence of load, etc. In addition, since the main spool of the main valve can be operated with fluid supplied from the secondary port of the pilot valve, there is no closing phenomenon of the variable orifice due to the axial thrust of the main spool, and the axial thrust It can operate normally even when the pressure is large, and the maximum flow rate of the pressure reducing valve can be increased.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] (1) One end side of the main spool (25) that switches the secondary port (B) to communicate with the primary port (A) and the tank port (T) is connected to the secondary port (B) through a passage, and the The main valves (21
) and the secondary port (b) to the primary port (a) and tank port (
one end side of the pilot spool (41) communicating with the secondary port (b) via a passage, and an adjustable pressing means (48) on the other end side of the pilot spool (41). 3-port pilot valve (22
), 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 primary port (A) of the main valve (21). Main spool (25
) A pressure reducing valve characterized in that the other ends of the valve are connected to each other.