JPH0158526B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a fluid control device.

(Prior art) A pressure control valve of the type that controls the pressure by the corner of the spool land, and moreover, in a pressure control valve with three or more ports, the control section has a spreading flow with a positive damping length and a negative damping length. A narrowing flow is now occurring. That is, FIG. 2 shows a conventional example in which a constant secondary pressure type 3-port pressure reducing valve 1 is used as a pilot valve for a flow rate control valve 2. A primary port 6 and a secondary port 7 are formed across a first pressure control section 5 formed in the land, and a secondary port 7 is formed across a second pressure control section 8 formed around the other corner of the land. 7 and a tank port 9, and a pilot chamber 10 at one end of the spool 3.
When the secondary pressure P2 acting on the spring 11 becomes smaller than the force of the spring 11, the opening degree of the first pressure control section 5 is increased to increase the value of the secondary pressure P2, and the secondary pressure P2 becomes smaller than the force of the spring 11. If it becomes too large, the opening degree of the second pressure control section 8 is increased to reduce the value of the secondary pressure P2, so that the secondary pressure P2 is maintained at the same value as the force of the spring 11.

(Problems to be Solved by the Invention) In the above case, the fluid passing through the first pressure control section 5 flows out from the center of the spool while spreading out in the same centrifugal direction, resulting in a so-called spreading flow. The fluid passing through the second pressure control section 8 flows out from the periphery of the spool toward the same center in a state symmetrical to that described above, resulting in a narrowing flow. It has been confirmed that in these two types of flow, the narrowing flow has a negative damping length and generates energy that increases the vibrations of the spool 3 compared to the widening flow with a positive damping length. In particular, since the pressure control valve is designed to operate with a high response even when the spool 3 has a small differential pressure, such narrowing of the flow as described above makes the spool 3 extremely unstable. Therefore, in the pressure control valve, a proportional solenoid is used in place of the spring 11, and by applying an electric dither to the proportional solenoid, the spool 12 of the flow control valve 2 is
Even if an attempt is made to resolve the sticking phenomenon, that is, the state in which the movement of the spool 12 is blocked by foreign matter, if the spool 3 of the pressure control valve is unstable, the secondary pressure P2 of the pressure control valve will become even more unstable. Therefore, a problem arises in that the flow rate control valve 2 cannot accurately control the flow rate.

Therefore, in view of the above points, the present invention provides a pressure control valve in which the first pressure control section and the second pressure control section each expand to form a flow, and provides an electric dither to the pressure control valve to control the flow rate. It is an object of the present invention to provide a fluid control device that can ensure flow rate control accuracy in a flow rate control valve while preventing the spool from sticking to the valve.

(Means for Solving the Problems) Therefore, the fluid control device of the present invention includes a pressure control valve 20 and a variable orifice 56 using the pressure control valve.
In the fluid control device comprising a flow control valve 44 whose opening degree is controlled, in the pressure control valve 20, the primary port P
, a tank port T, and a secondary port A are provided,
A spool 23 is slidably disposed within the housing 21, and by movement of a land 25 provided on the spool 23, the secondary port A is switched to communicate with the primary port P and the tank port T. ,
Furthermore, for the flow from the primary port P to the secondary port A, the flow is spread out at the first pressure control section 32 formed at the corner of one end surface of the land 25, while the flow is expanded at the secondary port A. In the second pressure control section 40, a flow is formed at a corner of the other end surface of the land 25 from the pilot chamber 28, which communicates with the pilot chamber 28 and is formed between the other end surface of the land 25 and the housing 21, to the tank port T. A proportional solenoid 47 is arranged on the side of the spool 23 opposite to the pilot chamber to urge the spool 23 toward the pilot chamber 28. On the other hand, the flow rate control valve 44 has a housing The opening of the variable orifice 56 is controlled by a spool 51 that is slidably disposed within the spool 50, and a pilot chamber 52 is provided for moving the spool 51, and the spool 51 is moved in the opposite direction to that described above. The secondary port A of the pressure control valve 20 is connected to the pilot chamber 52 of the flow control valve 44, and the proportional solenoid 4 of the pressure control valve 20 is connected to the pilot chamber 52 of the flow control valve 44.
A dither applying means is provided for applying electric dither to the spool 7 and vibrating the spool 23.

(Function) As described above, since the fluid flows through both the first pressure control section 32 and the second pressure control section 40 in a widening flow with a positive damping length, the fluid flows into a narrowing flow with a negative damping length as in the conventional case. does not act on the spool, making it possible to ensure the stability of the spool. Therefore, even if vibration is applied to this spool, a phenomenon in which the instability of the spool is not superimposed on the vibration does not occur, and therefore, while preventing the phenomenon of the spool 51 sticking to the flow control valve 44,
This allows highly accurate flow rate control.

(Embodiments) Next, specific embodiments of the fluid control device of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and this pressure control valve 20 has a primary port P and a tank port T.
This is a four-port pressure control valve having a housing 21 and two secondary ports A and B, and a spool 23 is slidably disposed in a valve chamber 22 formed in a housing 21 of the valve. This spool 23 has four lands 24, 25, 26, 27, and the one set of lands 24, 25 on the left side in the figure is for controlling the fluid in the secondary port A. A pair of lands 26, 27 on the right side is for controlling the fluid in the secondary port B. The lands 24 and 27 located at both ends of the above are pilot chambers 2 formed at both ends within the housing 21.
8, 29. Further, at both ends of the spool 23, a proportional solenoid 46,
47 iron cores 48 and 49 are opposed to each other. The proportional solenoids 46 and 47 have a characteristic of generating an attractive force proportional to the applied current value, and apply this attractive force to the spool 23 via the movable iron cores 48 and 49. The pair of lands 25 and 26 at the center of the spool 23 are for switching the primary port P to the secondary ports A and B, and when the spool 23 is in the neutral position, Port P is cut off from each secondary port A, B. In other words, both lands 2
This means that the distance L1 between the secondary ports A and B is smaller than the thickness L2 of the partition wall that partitions the secondary ports A and B. As a result, when the primary port P communicates with one of the secondary ports A or B, the other secondary port B or A is closed by the land 26 or 25. Furthermore, in the state where the primary port P is in communication with one of the ports A or B as described above, first pressure control portions 32 and 33 are formed between the periphery of the inner corner of the land 25 or 26 and the inner wall of the housing. be done.

On the other hand, each of the pilot chambers 28 and 29 is connected to the passage 3.
It communicates with the secondary ports A and B via ports 4 and 35. Furthermore, a pair of large diameter portions 38 and 39 are formed within the housing 21, and these large diameter portions 3
Reference numerals 8 and 39 can communicate with each of the pilot chambers 28 and 29, respectively. That is, the lands 24 and 27 provided at both ends of the spool 23 are connected to the pilot chamber 2.
8, 29, the pilot compartment 2
8, 29 and the large diameter portions 38, 39, but when the outer ends of the lands 24, 27 protrude from the pilot chambers 28, 29, the outer corners of each land 24, 27 are blocked. and the inner wall of the housing 21.
The fluid in the pilot chambers 28, 29 can communicate with the large-diameter portions 38, 39 via the holes 0, 41. Note that each of the large diameter portions 38 and 39 communicates with the tank port T. Further, the relationship between each of the large diameter portions 38, 39 and the secondary ports A, B is as follows. That is, when the first pressure control section 32 of one land 25 is in the controlled state, the outer end of this land 25 is connected to the large diameter section 38.
The relationship is such that a predetermined amount L3 overlaps with the partition wall that partitions the secondary port A and the secondary port A, thereby blocking the two. At this time, the other first pressure control section 32 is closed as described above, but the above-mentioned overlap is opened at the outer end of this land 26, and the secondary port B is connected to the large diameter section 39. It communicates with the tank port T and is open to the tank port T. It is assumed that the above-mentioned overlap amount L3 is made easy to open by demagnetizing the proportional solenoids 46 and 47.

Further, the first pressure control sections 32, 33 and the second pressure control sections 40, 41 have the following relationship. That is, the distance L4 between the ends of the lands 24, 25 and 26, 27 forming the first pressure control parts 32, 33 and the second pressure control parts 40, 41 on the spool 23 side, and the distance L4 between the ends of the lands 24, 25 and 26, 27 forming the first pressure control parts 32, 33 and the second pressure control parts 40, 41 on the spool 23 side, and parts 32, 33 and second pressure control parts 40, 41
The distance L5 between the inner walls forming the inner walls is the same. That is, the moment the first pressure control parts 32, 33 open, the second pressure control parts 40, 41 close, and the moment the first pressure control parts 32, 33 close, the second pressure control parts 40, 41 open. It is a relationship.

On the other hand, numeral 44 indicates a flow rate control valve, and this flow 44 supports a spool 51 slidably within a housing 50, and forms pilot chambers 52 and 53 at both ends of this spool 51, and Springs 54 and 55 as biasing means are arranged in pilot chambers 52 and 53. Each pilot chamber 52, 53 is connected to each secondary port A, B of the pressure control valve 20, and changes the fluid pressure acting in each pilot chamber 52, 53, thereby controlling the variable orifice 56. The opening degree can be controlled. Note that 45 indicates an actuator.

Next, the operating state of the fluid control device will be described, and the following description will be made regarding the case where fluid is controlled at one secondary port A. Note that the same control as described below is also performed at the other port B.

First, when the applied current value to the right solenoid 47 is increased, the spool 23 moves to the left to close the second pressure control section 40 and open the first pressure control section 32. Therefore, a spreading flow as shown by the arrow is generated in the first pressure control section 32 from the primary port P to the secondary port A, increasing the secondary pressure P2. This secondary pressure P2 is the proportional solenoid 4.
7, the spool 23 moves to the right contrary to the above, the first pressure control section 32 is closed, and the second pressure control section 40 is opened. Therefore, in the second pressure control section 40, the pilot chamber 28
A spreading flow as shown by the arrow is generated from the tank port T in the direction of the tank port T, reducing the secondary pressure P2. As a result, the spool 23 stands still so that the secondary pressure P2 and the suction force of the proportional solenoid 47 are balanced. As a result, the secondary pressure P in this flow control valve 20
2 is controlled to be proportional to the current value applied to the proportional solenoids 46 and 47, and the opening degree of the variable orifice 56 of the flow rate control valve 44 is also controlled accordingly. In this case, the corner portion opposite to the first pressure control section 33 on the right side and the second pressure control section 41 are both opened at an opening greater than the control range so as not to generate large resistance. The back pressure of the flow control valve 44 can be eliminated using the control unit 41 .

Ideally, the relationship between L4 and L5 in FIG. It is desirable to make it slightly larger. However, the length of L4 and L5
If the difference between the lengths of L4 and L5 is too large, the width of the dead zone will increase in accordance with the amount of overlap, and the responsiveness will decrease accordingly, so it is not preferable to make the difference between L4 and L5 too large. However, when the viscosity of the fluid increases or the flow rate increases, L4<L5 is also possible. Therefore, when the spool 23 is stationary, there is a difference between the amount of leakage from the annular gap around the first pressure control section 32 and the amount of leakage from the annular gap around the second pressure control section 40. A predetermined reduced pressure is obtained at the secondary port A. In this case, there is leakage corresponding to the overlap amount L3 at the overlap portion between the secondary port A and the large diameter portion 38, but the amount of leakage at the overlap portion is negligible. Furthermore, since the overlap portion L3 is not opened during control, the two lands 24 and 25 may have the same diameter, or in other words, the lands 24 and 25 may be formed into one land. However, it may also be implemented with one secondary port A. The claims are intended to cover such embodiments.

In this embodiment, the left and right sides are symmetrical, so when the suction force of the left solenoid 46 is increased, the symmetrical action causes the first pressure control section 33 on the right side and the first pressure control section 33 on the same side to increase. Two pressure control section 41
The secondary pressure acting on the right pilot chamber 53 of the flow control valve 44 is maintained constant, and the flow control valve 44
The back pressure in the left pilot chamber 52 can be eliminated by largely opening the left overlap L3 and the second pressure control section 40. Even in this case, the fluid in both pressure control units 33 and 40 is a spreading flow.

Next, the features of the above embodiment of the present invention will be explained.

That is, the flow rate control valve 44 operated by the pressure control valve 20 has particulates contained in the fluid stuck in the clearance around the spool land, so the spool 51 of the flow rate control valve 44 is vibrated and the spool is closed. Consideration must be taken to prevent the 51 from sticking. In this embodiment, a dither applying means (not shown) is provided, and electrical dither is applied to the spool 23 by the proportional solenoids 46 and 47, and the secondary pressure is fluctuated little by little. 51 sticking phenomenon can be eliminated. In particular, if the idea of solving the sticking phenomenon by adding an electric dither using a solenoid to a pressure control valve that inherently has an unstable spool like the conventional product, the pressure control valve itself becomes extremely unstable and becomes stuck. Even if the phenomenon is resolved, the control accuracy will decrease, but in the above embodiment, the spool 23 is stabilized in advance by the spreading flow in both pressure control sections 32, 33 and 40, 41, so the spool is not as strong as the conventional product. There is an advantage that the sticking phenomenon of the spool 51 of the flow rate control valve 44 can be solved by the electric dither without causing instability.

In addition, in this embodiment, the land for controlling the fluid at one secondary port A or B always consists of two lands 24, 25 and 26, 27, and the overlap L3 is caused by an excessive pressure change during control. Proportional solenoid 46 will not open unless
When the pressing force of the spool 23 is removed by demagnetizing the spool 23, it is easy to open the spool 23. The possibility that the overlap will open depends on the magnitude of the secondary pressure P2, but the smaller the overlap amount L3, the greater the degree of opening even if the secondary pressure P2 is small. Therefore, by demagnetizing the proportional solenoid 46, the secondary port B and the tank port T
As shown by the dotted line arrow in the right half of the figure, they communicate with each other through the second pressure control section 41 and around the left corner of the middle land 26, so that the secondary pressure P2 can be rapidly increased. Can be opened to atmospheric pressure. As a result, this embodiment has the advantage that the flow control valve 44 connected to the secondary ports A, B can be operated remotely and with high response via the proportional solenoids 46, 47.

Further, when the spool 23 moves from the neutral position and, for example, one pressure control section 32 is slightly opened, the other second pressure control section 41 is largely opened, that is, one first pressure control section 32 is opened. By setting the relationship such that the opening degree of the other second pressure control section 41 is always larger than the opening degree of the second pressure control section 41, the second pressure control section 41 controls the flow of fluid opened from the pilot chamber 29 to the tank port T. Since it does not act as resistance, it is possible to further improve the responsiveness of the spool of the flow control valve 44.

(Effects of the Invention) As described above, the present invention closes the part corresponding to the conventional secondary pressure control part in a constant secondary pressure pressure control valve so that it does not open during control, and instead closes the part of the spool 23 that corresponds to the conventional secondary pressure control part. A second pressure control section 40 is formed between the pilot chamber 28 at one end of the spool and the tank port T around the land corner at one end. Therefore, in the first pressure control section 32, the flow is widening as in the conventional case, and especially in the second pressure control section 40, which was conventionally a narrowing flow, the flow is widening, and the narrowing flow that makes the spool 23 unstable is eliminated. Therefore, the spool vibration can be prevented, and as a result, the generation of noise can be prevented, and the control accuracy of the secondary pressure can be improved. Furthermore, a proportional solenoid 47 is provided, and the solenoid 47 applies an electric dither to the spool to eliminate the sticking phenomenon of the flow control valve 44 controlled by the pressure control valve, so that it is essentially stable. Since the dither is added to a good spool, it is possible to eliminate the sticking phenomenon without making the spool so unstable, that is, while maintaining high flow rate control accuracy in the flow rate control valve 44.

Furthermore, in the present invention, even with a single dither applying means, it is possible to simultaneously vibrate the two spools of the pressure control valve and the flow rate control valve and prevent them from sticking. The configuration can be simplified compared to the case where a dithering means is provided. Furthermore, since the flow rate control valve has a large control flow rate, the overall size becomes large.
In order to vibrate the spool, a high-output dither applying means is required, but in the present invention, the spool is vibrated even by pressure fluctuations in the pilot chamber, so a high-output dither is required. The advantage also arises that no application means are required.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is an explanatory diagram of a conventional example. 20...Pressure control valve, 21...Housing, 23...
Spool, 24, 25, 26, 27...Land, 2
8, 29... Pilot chamber, 32, 33... First pressure control section, 40, 41... Second pressure control section, 44... Flow rate control valve, 46, 47... Proportional solenoid, 50...
Housing, 51... Spool, 52, 53... Pilot chamber, 54, 55... Spring, 56... Variable orifice, P... Primary port, A, B... Secondary port, T... Tank port.

Claims (1)

[Claims] 1. A pressure control valve 20, and a flow rate control valve 4 in which the opening degree of a variable orifice 56 is controlled by this pressure control valve.
4, in the pressure control valve 20, the primary port P
, a tank port T, and a secondary port A are provided,
A spool 23 is slidably disposed within the housing 21, and by movement of a land 25 provided on the spool 23, the secondary port A is switched to communicate with the primary port P and the tank port T. ,
Furthermore, for the flow from the primary port P to the secondary port A, the flow is spread out at the first pressure control section 32 formed at the corner of one end surface of the land 25, while the flow is expanded at the secondary port A. In the second pressure control section 40, a flow is formed at a corner of the other end surface of the land 25 from the pilot chamber 28, which communicates with the pilot chamber 28 and is formed between the other end surface of the land 25 and the housing 21, to the tank port T. A proportional solenoid 47 is arranged on the side of the spool 23 opposite to the pilot chamber to urge the spool 23 toward the pilot chamber 28. On the other hand, the flow rate control valve 44 has a housing The opening of the variable orifice 56 is controlled by a spool 51 that is slidably disposed within the spool 50, and a pilot chamber 52 is provided for moving the spool 51, and the spool 51 is moved in the opposite direction to that described above. A biasing means 55 for biasing the pressure control valve 20 is connected to the pilot chamber 52 of the flow rate control valve 44, and a proportional solenoid 4 of the pressure control valve 20 is connected to the pilot chamber 52 of the flow rate control valve 44.
7. A fluid control device characterized in that a dither applying means for applying an electric dither to vibrate the spool 23 is provided.