JPH0433050B2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a three-port pressure reducing valve.

<Prior art> Conventionally, there is a three-port pressure reducing valve of this type as shown in FIG.
Publication No.). This three-port pressure reducing valve has a spool 2 slidably fitted into a valve chamber 9 formed in a main body 1, and a pressure from a secondary port B is passed through a pilot chamber 3 formed at one end of the spool 2. At the same time, the other end of the spool 2 is pressed by the electromagnetic proportional solenoid 5, so that the pressure P _B of the secondary port B, that is, the pressure of the pilot chamber 3, and the pressing force of the electromagnetic proportional solenoid 5 are opposed. Then, the spool 2 is operated to control the pressure P _B at the secondary port B. The flow from the primary port A to the secondary port B is controlled by the first pressure control section 6a in which the spool 2 is formed at the corner of one end surface of the land 2a.
A second pressure control 6b is configured to form a widening flow that spreads out from the axis of the spool 2 in a tassel shape, and a flow from the pilot chamber 3 leading to the secondary port B to the tank port T is formed on one end surface of the land 2b of the spool 2.
By configuring it so that the flow spreads out in a ripple shape, the so-called narrowing flow that makes the spool 2 unstable is eliminated, and the flow from the primary port A to the secondary port B, and from the pilot chamber 3 to the tank port T. The spool 2 is stabilized against the flow of water, and vibration and noise are prevented from occurring.

<Problems to be Solved by the Invention> However, in the conventional three-port pressure reducing valve described above, the pressure P _B of the secondary port B led to the pilot chamber 3 and the electromagnetic proportional solenoid are limited in the magnitude of the force. There is a problem that the pressure P B of the secondary port B cannot be controlled to a high pressure because the pressure force of the secondary port B is directly opposed to that of the pressure P _B of the secondary port B. In other words, when controlling the pressure P _B at the secondary port B to a high pressure with the electromagnetic proportional solenoid 5, outputting the necessary pushing force means that the dimensions of the electromagnetic proportional solenoid 5,
Practically impossible due to weight. Furthermore, if the diameter of the spool 2 is increased in an attempt to control a large flow rate, the fluid force applied to one end of the spool 2 on the pilot chamber 3 side also increases, and the pressing force of the electromagnetic proportional solenoid 5 opposes this fluid force. I can't. That is, the conventional three-port pressure reducing valve described above has a problem in that it cannot control a large flow rate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to make it possible to set the secondary pressure at a high pressure and control a large flow rate while maintaining the stability of the spool due to the spreading flow.

<Means for Solving the Problems> In order to solve the above problems, the three-port pressure reducing valve of the present invention reduces the flow from the primary port A to the secondary port B, as illustrated in FIG. Main spool 1
The flow spreads in the first pressure control section 31 formed at the corner of one end surface of one land 13b of 3, while the flow is expanded from the pilot chamber 18 formed at one end side of the main spool 13 and communicated with the secondary port B. The flow to tank port T is transferred to the main spool 13 above.
This is a three-port type pressure reducing valve equipped with a main valve 11 configured to spread out and form a flow at a second pressure control section 32 formed at the corner of one end surface of another land 13a, the other end of the main spool 31 being While forming a spring chamber 25 in which a spring 23 is compressed on the side,
It is characterized in that the secondary port B and the spring chamber 25 are communicated through a passage 27 having a throttle 26, and that a pilot relief valve 22 is connected to the spring chamber 25.

<Function> With the above configuration, the spring chamber 25 on the other end side of the main spool 13 communicates with the secondary port B via the passage 27 having the throttle 26, and the pressure in the spring chamber 25 is controlled by the pilot relief valve 22. , controlled to a predetermined set pressure. Therefore, the main spool 13 of the main valve 11 is connected to the pilot chamber 18 and the spring chamber 25.
The pressure difference between the pressure at the primary port A and the
The pressure is reduced from this pressure to a predetermined pressure. In this way, the pressure in the pilot chamber 18 leading to the secondary port B and the pressure in the spring chamber 25 are made to oppose each other, and the main spool 13 is actuated, so that the flow from the primary port A to the secondary port B, and the pressure in the pilot chamber 18 Since the pressure in the secondary port B is controlled to be reduced by regulating the flow from the tank to the tank port T, the secondary pressure in the secondary port B can be set to a high pressure even with a small operating force of the pilot relief valve 22. By making the main spool 13 large in diameter, a large flow rate can be controlled. Also, main valve 1
1 first pressure control section 31 and second pressure control section 3
Since the flow in the main spool 13 is configured so that it spreads out, the operation of the main spool 13 is stable, and generation of vibration and noise is prevented.

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

In Fig. 1, 11 is a 3-port main valve, 2
2 is a pilot relief valve.

The main valve 11 has a valve chamber 12 formed in the main body 10.
A main spool 13 having three lands 13a, 13b, and 13c is slidably fitted to the main spool 13. The valve chamber 12 is provided with annular grooves 15, 16, 17 spaced apart from each other from the left in FIG. It communicates with port B and primary port A, respectively. The pilot chamber 18 at one end of the main spool 13 is communicated with the secondary port B via a passage 24 having a throttle 21, while the spring chamber 25 at the other end of the main spool 13 in which the spring 23 is compressed is connected to the pilot chamber 18 at one end of the main spool 13. , and communicates with the secondary port B via a passage 27 having a throttle 26. Therefore,
The main spool 13 is operated by the balance between the fluid pressure in the pilot chamber 18 and the fluid pressure in the spring chamber 25, and the differential pressure between the fluid pressure in the pilot chamber 18 and the fluid pressure in the spring chamber 25 is 23, the opening degree of the first pressure control section 31 formed at the corner of the right end surface of the land 13b, and the opening degree of the second pressure control section 32 formed at the corner of the left end surface of the land 13a. The third pressure control section 33 is formed at the corner of the left end surface of the land 13b.
The opening degree of the valve is controlled. Since the diameter of the annular groove 16 is larger than the diameter of the valve chamber 12 in the first pressure control section 31, the flow from the primary port A to the secondary port B spreads out from the axis of the main spool 13. It spreads and becomes a flow. Furthermore, the flow from the pilot chamber 18 to the tank port T is as follows:
In the second pressure control section 32, since the diameter of the annular groove 15 is larger than the diameter of the pilot chamber 18, the flow spreads. Therefore, the operation of the main spool 13 is stable, and no vibration or noise is generated.

As shown in FIG. 1, the distance between the left end surface of the land 13a of the main spool 13 and the left end surface of the annular groove 15 is _L2 , the distance between the left end surface of the land 13b and the left end surface of the annular groove 16 is _L3 , Assuming that the distance between the right end surface of the land 13b and the right end surface of the annular groove 16 is _L1 , the following relationships are established: _L3 > _L2 , _L3 > _L1 , and _L1 ≧< _L2 . That is, when the relationship between L ₁ and L ₂ is L ₁ >L ₂ , the third pressure control section 33 from the secondary port B to the tank port T controls the second pressure from the pilot chamber 18 to the tank port T. Part 32
is opened and the first pressure control section 31 from the primary port A to the secondary port B is closed, and in the case of L ₁ <L ₂ , the third pressure control section 33 is opened. If the second pressure control section 32 is opened after the first pressure control section 31 is closed, it will open for the first time. Further, in the case of L ₁ =L ₂ , the third pressure control section 33 opens only when the first pressure control section 31 closes and the second pressure control section 32 opens at the same time.

A pilot relief valve 22 is interposed in a passage that communicates the spring chamber 25 of the main valve 11 with the tank 40. The pilot relief valve 22 is configured to control the pressure by pressing a poppet 42 against a valve seat 41 with an adjustment handle 43 via a pressure adjustment spring 45.

A hydraulic cylinder 55 is connected to the secondary port B of the main valve 11 through a passage 56.
A pressure source 57 is connected to the next port A via a passage 58.

In the above configuration, the pilot relief valve 22
The control pressure of the pilot relief valve 22 is set to a constant pressure by operating the adjustment handle 43, and the pressure of the spring chamber 25 of the main valve 11 is controlled to a constant pressure. Then, the main spool 13 of the main valve 11 becomes
The first pressure control section 31 and the second pressure control section 32 operate so that the differential pressure between the fluid pressure in the pilot chamber 18 and the fluid pressure in the spring chamber 25 becomes a value corresponding to the spring force of the spring 23. The pressure of the secondary port B is controlled to a predetermined pressure by controlling the opening degree of the secondary port B. Also,
When it is desired to lower the pressure of the secondary port B during control, the second pressure control section 32 is opened by lowering the set value of the pilot relief valve 22, so that the pressure of the secondary port B matches the setting of the pilot relief valve 22. It drops instantly in response to pressure. At this time, the first
The fluid flowing through the pressure control section 31 spreads and flows, and also flows from the pilot chamber 18 to the tank port T.
The fluid flowing through the second pressure control section 32 toward the direction expands and becomes a flow. Therefore, the pressure control operation of the main spool 13 is stable, and generation of vibration and noise is prevented. Note that the passage 24 leading to the pilot chamber 18
The throttle 21 provided in the main valve 11 is a damper throttle, and effectively performs a damping action to make the operation of the main valve 11 more stable.

Further, the pressure in the spring chamber 25 of the main valve 11 is controlled by the pilot relief valve 22, so that the fluid pressure in the pilot chamber 18 of the main valve 11 and the fluid pressure in the spring chamber 25 are opposed to each other, so that the main spool 13 Since the pressure at the secondary port B is controlled to be reduced by operating the main valve 11, the pressure at the secondary port B of the main valve 11 can be controlled to a high pressure even with a small pressing force of the pressure regulating spring 45 of the pilot relief valve 22. Furthermore, by making the main spool 13 large in diameter, a large flow rate can be controlled.

Note that the third pressure control section 33 of the main valve 11 opens when the pressure at the secondary port B becomes excessively high even when the second pressure control section 32 is fully opened.

<Effects of the Invention> As is clear from the above, according to this invention,
While maintaining the stability of the pressure control operation of the main spool of the main valve due to the spreading flow, the secondary pressure can be set to a high pressure, making it possible to control a large flow rate.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a three-port pressure reducing valve according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a conventional three-port pressure reducing valve. DESCRIPTION OF SYMBOLS 11...Main valve, 13...Main spool, 18...Pilot chamber, 22...Pilot relief valve, 23...Spring, 25...Spring chamber.

Claims (1)

[Scope of Claims] 1. The flow from the primary port A to the secondary port B is made into a spreading flow in the first pressure control section 31 formed at the corner of one end surface of one land 13b of the main spool 13; A second pressure control system in which the flow from the pilot chamber 18, which is communicated with the secondary port B and is formed at one end of the main spool 13, to the tank port T is formed at the corner of one end surface of another land 13a of the main spool 13. This is a three-port pressure reducing valve equipped with a main valve 11 configured to spread out at a portion 32, and a spring chamber 25 in which a spring 23 is compressed is formed on the other end side of the main spool 31. A passage 27 having a throttle 26 connects the secondary port B and the spring chamber 25.
The three-port pressure reducing valve is characterized in that a pilot relief valve 22 is connected to the spring chamber 25.