JPS61285515A - Pressure reducing valve - Google Patents

Abstract

PURPOSE:To reduce a leakage flow rate by securing the linkage between the port of a pilot valve and the prescribed areas of both a main valve and a main spool respectively and attaining the control of the secondary pressure over the entire area. CONSTITUTION:For a 3-port type main valve 21, a chamber on the end face at the spool side of a main spool 25 having a spool part coupled with switching to a primary port A and a tank port T and a piston part having a larger diameter than the spool part is coupled to a secondary port (a) of the valve 22 is coupled to the primary port a of the valve 21. While the secondary port (b) of the valve 22 is coupled to a chamber of the piston part.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is suitable for use, for example, in controlling hydraulic cylinders for clutches in automobiles, and is capable of controlling secondary pressure over a wide range from zero pressure to a value equal to the primary pressure. It relates to a controllable pressure reducing valve.

<Conventional technology>
y Conventionally, a pressure reducing valve and a poppet-type three-bottom pilot valve for the main valve (1), as shown in Figure 7, are used.
11.

(2) is known (Hydraulic technology, 24)
.

Vol., No., p. 4.2I). This pressure reducing valve is the main valve (1)
1': Vent throttle (5) that forms a vent flow from the secondary port (B) side of the pilot valve (2) to the port (3) of the pilot valve (2).
A pilot passage (6) with (□・; ; ;
The fluid pressure between the first throttle (5) and the poppet (3) is introduced into the spring chamber (8) at one end of the main spool (7) of the main valve (1).
On the other hand, the pressure at the secondary port (B) of the main valve (1) is
[;1'1 Lead to the pilot room (g) at the other end of the pool (7)
+].

There is. In other words, the main spool (7) has a pilot chamber.
:), '(9) fluid pressure and spring chamber (8
) is opposed by the resultant force obtained by adding the force of the spring (10), and when the fluid pressure of the secondary port (B) reaches the set pressure of the pilot valve (2), the pilot valve (2)
The valve 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 narrow the opening of the variable orifice (4), and the secondary port (B ) to reduce the pressure. 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 becomes zero, eliminating the differential pressure across the vent throttle (5) and causing the spring ( 10) Main spool (7) by force
to the right in Fig. 5 to widen the opening degree of the variable orifice (4) and supply fluid from the primary port (A) to the secondary port (B). increase the pressure,
The pressure is controlled to the desired set pressure. Also, the secondary port (B
) to the tank port (T) <Problem to be solved by the invention> However, in the above conventional pressure reducing valve, the main spool (7
) is led from the secondary port (B) side, so there is a problem that the minimum control pressure becomes high. That is, even if the pressing force of the electromagnetic solenoid (11) of the pilot valve (2) is zero and the poppet (3) is fully opened, the spring (
10) In order to overcome the spring force, a pressure of 1.5 to 2 kg/cm' is generally required as the pressure at the secondary port (B), so the minimum control pressure at the secondary port (B) is There is a problem in that the pressure inevitably exceeds 1.5 to 2 kg/cm'' and the secondary pressure cannot be controlled from approximately zero pressure.

In addition, in conventional pressure reducing valves, there is a vent throttle (5) from the secondary port (B) of the main valve to the pilot valve (2).
Since the pilot flow (vent flow) passing through the vent throttle (vent flow) obtains the pilot pressure that operates the main spool (7), a constant amount of vent flow rate is constantly generated to create a constant differential pressure before and after the vent throttle (5). The disadvantage is that a certain amount of vent flow is required even at the lowest control pressure, and the power loss is large.

Therefore, the main purpose of this invention is to be able to control the secondary pressure over the entire range from completely low pressure (zero pressure) to equal to the primary pressure, and thereby to control the pressure of the clutch hydraulic cylinder etc. connected to the secondary port. The actuator can be started softly and smoothly from low pressure, and can also be operated at high pressure equal to the primary pressure.

Another object of the present invention is to eliminate the vent flow from the secondary port of the main valve and introduce pilot pressure from the primary port side of the main valve, so that the leakage flow rate (
The goal is to reduce the drain flow rate.

<Means for Solving the Problems> In order to achieve the above object, the pressure reducing valve of the present invention connects the secondary port (B) to the primary port (A) as illustrated in FIG.
and the tank port (T) through a passageway through a chamber on the end face of the spool part of the main spool (25), which has a spool part that communicates with the spool part and a piston part whose diameter is larger than the diameter of the spool part. The 3-port main valve (21) communicates with (B), and one end of the pilot spool (41) communicates the secondary port (b) with the primary port (a) and tank port (t). A three-port pilot valve (22) in which the chamber is communicated with the secondary port (b) through a passage and a pressing means is provided at the other end 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 primary port (A) of the main valve (21). The main spool (25) is characterized in that it communicates with the chambers on the piston section side.

Function> With the above configuration, the pressing means (4) of the pilot valve (22) is used to adjust the secondary pressure (PB) of the main valve (21) to approximately zero pressure.
8), the operation of the pilot spool (41) due to the balance between the pressure (pb) in the chamber at one end of the pilot spool (41) and the pressing means (48) causes the primary port ( a) and the secondary port (b
) and close the gap between the secondary board (b) and the tank port (
t). The chamber on the piston side of the main spool (25) of the main valve (21) is connected to the pilot valve (22).
), and the pressure in the chamber on the piston side is controlled to zero pressure. Therefore, the main valve (21
The main spool (25) of the main spool (25) operates by the balance between the chamber on the spool side and the chamber on the piston side.
5) moves to the right in Figure 1, connects the secondary port (B) and tank bow (T), and controls the pressure of the secondary port (B) of the main valve (21) to zero pressure. do. Further, the pressing means (48) of the pilot valve (22) is changed from zero pressure to the main valve (22).
When the pressure is controlled to a pressure corresponding to the pressure between the primary pressure (PA) of 1), the pressure of the pilot valve (22) is adjusted accordingly.
The secondary pressure (pb) and the pressure in the chamber on the piston side of the main valve (21) are controlled, and the main spool (25) operates by balancing the pressure in the chamber on the piston side and the pressure in the chamber on the spool side. Thus, the pressure (PB) of the secondary bow 1-(B) of the main valve (21) is controlled to a desired reduced pressure. Main valve (21
) When the secondary pressure (PB) of Since the spool (25) is actuated, even if the spring (31) that presses the main spool (25) is used, the main The spool (25) is movable by compressing the spring (31), and the pressure can be controlled so that the primary pressure (PA) and the secondary pressure (Pa) of the main valve (2I) are equal.

When the secondary pressure (Pa) of the main valve (21) is controlled to be equal to the primary pressure (PA), or when the main valve (21)
The pilot spool (41) and the main spool (25) can be at the stroke end position when the secondary pressure (PB) of the There is almost no drain flow rate from the primary ports (a) and (A) of (21).

Therefore, power loss is small.

Also, the main spool (25) is inserted through the pilot valve (22).
), which has a large pressure-receiving area, is supplied with pressure fluid to act on it, so the main spool (25) is operated with a large force against the axial thrust (flow force) acting on the main spool (25). Therefore, it is possible to resist axial thrust and increase the maximum flow rate.

<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 spool (25) of the main valve (21) has three lands (25a-1), (25a-2), (25a
-3) and a piston part (25b) having a larger diameter than the spool part (25a) are integrally formed. The above land (25a-1), (25
a-2).

(25a-3) and the piston part (25b) are the main body (20)
It is slidably fitted. The above piston part (25b)
The diameter of land (25a-1), (25a-2), (
25a-3). Then, the land (25a-
In 2), the secondary port (B) is switched to communicate with the primary port (A) and the tank port (T). A spring (
The spring chamber (28), which is a reduced version of 31), has a pilot passage (
29) to the secondary port (B). The opening (29a) that opens to the land (25a-2) of the pilot passage (29) is always connected to the secondary port (B).
(The dimensions of the main spool (25) are determined so as to communicate with each other. Also, a pilot chamber (32) is provided at the other end of the main spool (25) on the piston part 1 (25b) side.
There is. The piston part (25b) and the land (25a-
3) Jin:・ One hour o! (66)! ! Communication path 53 sweat 0'''?y7 (6
1) i is connected. Therefore, the main valve (21) is operated by the differential pressure between the pilot chamber (32) and the spring chamber (28).
(31) Adjust the main spring so that the force corresponds to the spring force of the spring (31).
Operate the i-rule (25) to change the distance between the secondary port (B), the primary μ port (A), and the tank port (T).
1.i.

Controls the opening degree of the orifuus (26) and (30).
:・)゛On the other hand, the above pilot valve (22) is normally closed.
(, 1 (P. 1.: l -D type, depending on the operation of the pilot spool (41).
:,.

Connect the secondary port (b) to the primary port using the land (41).
il (a) and tank port (t)
It is designed to switch and communicate. One end side of the pilot spool (41) 1° chamber (4
5) is connected to the secondary port (
b) is connected. The chamber of the pilot valve (22) (
45) is compressed with a spring (47).

On the other hand, on the other end side of the pilot spool (41),
An electromagnetic proportional solenoid (48) as an example of adjustable pressing means is provided, and the center of the pilot spool (41) is connected to the plunger (48a) of the electromagnetic proportional solenoid (48).
The pressure is applied with a force proportional to the energization value (i) of the current. The plunger (48a) is pressed toward the pilot spool (41) by a balancing spring (49). The spring force of the spring (47) is the spring force of the spring (47).
The spring force is slightly stronger than 9). The left end of the pilot spool (4I) is provided with an engaging part (41b) for engaging and positioning the surrounding main body, and in the normal position, the primary port (a) and the secondary port (b) are connected. I'm trying to close the gap. That is, the pilot valve (22)
is normally closed type. 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 in 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 the pilot passage (5I).
A), and also connects to 2 of the pilot valve (22).
The next port (b) is the piston part (25b) of the main valve (21)
It is connected to the pilot chamber (32) on the side via a pilot passage (52). The tank port (t) of the pilot valve (22) and the chamber (65) containing the plunger (48a) are connected to the tank (61) through a drain passage (53).
).

Further, the secondary port (B) of the main valve (2[) is connected to the clutch cylinder (55) of the automobile via a passage (56), and the primary port (A) is connected to the pressure source (57) through a passage. (58
), and the tank port (T) is connected through the passage (71)
It is connected to the tank (61) via.

In the above configuration, the current value (i) of the current flowing through the electromagnetic proportional solenoid (48) of the pilot valve (22)
When , the pilot spool (41) of the pilot valve (22) is pushed to the right in Fig. 1 by the spring force of the spring (47), and the primary port (a) is
) and the secondary port (b).
) and tank port (t) fully open. Therefore, the pilot chamber (32) of the main valve (21) is connected to the passage (52).
, communicates with the tank (6I) via the tank port (t), and the main spool (25) of the main valve (21) is connected to the spring chamber (28).
is pressed by the spring (31), moves to the right in Fig. 1,
Close the space between the primary port (A) and the secondary port (B) with the land (25a-2), fully open the space between the secondary port (B) and the tank port (T), and close the space between the secondary port (A) and the secondary port (B). The pressure in (B) is controlled to zero pressure. At this time, the drain flow rate from the primary port (A) of the main valve (21) and the primary port (a) side of the pilot valve (22) is substantially less than during the pressure control described below.

Next, the electromagnetic proportional solenoid (4) of the pilot valve (22)
8), as the current value (i) increases, the operation of the pilot spool (41) causes
Secondary port (b) and main valve (21) pilot chamber (
32) pressure increases. The main spool (25) of the main valve (2I) absorbs the fluid pressure acting on the pilot chamber (32) on the piston portion (25b) side and the spring chamber (28).
) operates so that the force due to the differential pressure between the fluid pressure of the secondary port (B) and the fluid pressure of the secondary port (B) acting on the
Control the pressure at the next port (B). At this time, the main valve (2
Drain fluid necessary for control is discharged from both the tank port (T) of 1) and the tank port (t) of the pilot valve (22).

Furthermore, the electromagnetic proportional solenoid (
When the current value (i) applied to the pilot valve (22) is increased by a certain value or more, the pilot spool (41) of the pilot valve (22)
) moves to the left in Figure 1 to fully open between the primary port (a) and secondary port (b), and fully open between the secondary port (b) and tank port (t). Then, the pressure of the primary port (a) is guided to the pilot chamber (32) of the main valve (21) via the passage (52). Therefore, the pressure of the primary port (a) acts on the piston part (25b) having a larger cross-sectional area, and the main spool (25) moves to the left in FIG. Fully open the space between the secondary port (F3) and completely close the space between the secondary port (B) and the tank port (T).

Then, the secondary pressure (Pa) of the secondary port (B) is controlled to be equal to the primary pressure (PA, ) of the primary port (A).

At this time, the drain flow rate from the tank port (T) of the main valve (2I) and the tank port (t) of the pilot valve (22) is substantially lower than during the pressure control described above, and therefore the power loss is reduced. There is.

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 (PB) of the secondary port (B) of the main valve (21). Then, the secondary pressure (PR) changes from Okg/cm' to the current value (i
), and it can be seen that when the current value (i) exceeds a certain value, P B =PA. Furthermore, Fig. 3 is a graph showing the relationship between the total leakage amount (drainage amount) from both tank ports (T) and Q) of the main valve (21) and pilot valve (22) with respect to the above current value (i). in,
It can be seen that the amount of leakage decreases when the secondary pressure (PB) is at the lowest control pressure (approximately zero pressure), at the highest control pressure (when P a =PA), and in a region connected thereto.

In this way, this pressure reducing valve is connected to the main spool (2I) of the main valve (2I).
Since the pilot pressure that operates the main spool (25) is led from the primary port (A) side, even if the pressure at the secondary port (B) is controlled to an extremely low pressure close to zero, the main spool ( 25) can be operated to perform pressure reduction control, and the pressure at the secondary port (B) can be controlled from zero pressure. Since the pressure at the secondary port (B) can be controlled from zero pressure in this way, the clutch hydraulic cylinder (55) can be started extremely softly and without shock. Furthermore, by increasing the pressing force of the electromagnetic proportional solenoid (48), the pressure at the secondary port (B) can be controlled to a pressure equal to the pressure at the primary port (A). In this way, this pressure reducing valve can be used from extremely low pressure close to zero pressure to one □-8 (A,
. 1 ke ka. 2゜6oyu, Iekayo 7. :The secondary pressure of the secondary port (B) over a wide range of
i(P·) can be controlled.
1. Also, the main spool (25) of the main valve (21) is supplied with fluid pressure to the piston portion (25b) to act on it.

Since the main spool (25) is operated, the axial thrust (flow force) acting on the main spool (25)
In response, the main spool (25) can be actuated and the maximum flow rate of the main valve (21) can be increased.

Fig. 4 shows another embodiment, in which the primary port (a) and tank port (t) of the pilot valve (22) are replaced with the one shown in Fig. 1 to make it a normally open type. , the plunger (48a) of the electromagnetic proportional solenoid (48)
) The pressure of the secondary bow (b) is introduced into the chamber (65) containing the pressure of the secondary bow (b). 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. 4, a spring (47) serves as a pressing means, and as the pressing force of the electromagnetic proportional solenoid (48) becomes stronger, the pressing force of the spring (47) against the pilot spool (4I) becomes relatively weaker. Therefore, as shown in FIG. 5, as the current value (D) increases, the secondary pressure (PB) of the main valve (21) decreases.

Note that until the current value (i) reaches the set value, the spring (47
) is much stronger than the spring force of the spring (47), the space between the primary port (a) and the secondary port (b) of the pilot valve (22) is fully opened, and the main valve (21 )of"'"
, +7 (PA) “″”°゛゛°″”°°“ao
l), jAlso, the amount of leakage (0) for this example 0 current value (i).

[・1 The characteristics are shown in FIG. 6 and are similar to those in FIG. 3.
[In addition, in the above example, (Y, main valve (2□
),) The spool part (25a) and piston part (25b) of the main part (25)
i has an integral structure, but the spool part (25a
) and the piston portion (25b) may have a separate structure. t) <Effects of the invention>
i・1
1.O.

As is clear from the above, the pressure reducing valve of the present invention is
Mi...j",... Chamber on the piston side of the main spool of the 3-port main valve
1゜'j・: The primary valve of the main valve is connected to the main valve via the 3-port pilot valve.
,・.

Chair 1'' (A) side'' Feeding 01/1 valve 02 1-) - (B
) > side is not communicated,
Extremely low secondary port 1);:.

The main spool of the main valve is operated even in the pressure-down control state.
((.

□、4yuyoka、751.7ka1. A2nie. workman
[i゛[11 The force can be controlled to an extremely low pressure close to zero pressure, and the primary
fl] [,] Can be controlled to a high pressure approximately equal to one pressure, and can be used over a wide range.
((Pressure control can be performed across the range. Therefore, the actuator connected to this pressure reducing valve can be started very softly from a low pressure without shock, and this actuator can be operated at a high pressure approximately equal to the primary pressure.) But it can be activated.

Further, since the pressure reducing valve of the present invention does not perform pressure control by a constant flow rate of vent flow from the secondary port side via the vent throttle as in the conventional case, the amount of leakage can be reduced overall. In addition, the main spool can be operated by applying the pressure of the fluid supplied from the primary port to the secondary port of the pilot valve to the piston of the main spool, so the main spool can be operated even under large axial thrust. , the maximum flow rate of the pressure reducing valve can be increased. Further, since the main spool is operated by increasing the force in the piston portion, the secondary pressure of the main valve can be controlled over a wide range from approximately zero pressure to a value equal to the primary pressure.

[Brief explanation of drawings]

Figures 1 and 4 are principle diagrams of an embodiment of the present invention, Figures 2, 3, 5, and 6 are characteristic diagrams of the above embodiment, respectively, and Figure 7 is a diagram of the conventional example. In the cross-sectional view, 21...main valve, 2
2...Pilot valve, 25...Main spool,
25a... Spool portion, 25b... Piston portion, 41... Pilot spool, 48... Electromagnetic proportional solenoid.

Claims (1)

[Claims] (1) A main spool (25) having a spool portion that switches and communicates the secondary port (B) with the primary port (A) and the tank port (T), and a piston portion having a diameter larger than the diameter of the spool portion. A 3-port main valve (21) in which the chamber on the end face of the spool portion communicates with the secondary port (B) through a passage.
And, connect the secondary port (b) to the primary port (a) and tank port (
t), a chamber at one end of the pilot spool (41) communicating with the secondary port (b) via a passage, and a pressing means provided at the other end 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 of the pilot valve (22) is connected to the primary port (A) of the main valve (21). A pressure reducing valve characterized in that the ports (b) are communicated with chambers on the piston side of the main spool (25) of the main valve (21).