JPS6074005A - Pressure control valve - Google Patents

Abstract

PURPOSE:To prevent spool oscillation and also to prevent the generation of noise by forming the 2nd pressure control part between a pilot chamber at one end of a spool and a tank port. CONSTITUTION:When the spool 23 is moved to left by operating a right-side screw rod 43, the 2nd pressure control part 40 is closed and the 1st pressure control part 32 is opened. A spread flow is generated in the direction from a primary port P to a secondary port A raise secondary pressure P2. When the secondary pressure P2 exceeds the force of a spring 31, the spool 23 moves to right to close the 1st pressure control part 32, and the secondary pressure control part 40 is opened. A spread flow is generated in the direction from the pilot chamber 28 to a tank port T at the secondary pressure control part 40 to reduce the secondary pressure P2. Then, the spool 23 stops where the secondary pressure P2 balances with the force of the spring 31.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a pressure control valve which stabilizes a spool during a control operation.

(Prior art) In a pressure control valve that controls pressure by the corner of a spool land, and has three points or more, the control section has a spreading flow with a positive damping length and a negative damping length as shown below. A pinched flow is generated. That is, FIG. 3 shows a constant secondary pressure type 3-port 1-pressure reducing valve 1 with a guide valve 2.
This shows a conventional example used as a pilot valve for
The pressure reducing valve (2) forms a primary boat 6 and a secondary boat 7 with a first pressure control section 5 formed around an example corner of the spool land 4, and also forms a primary boat 6 and a secondary boat 7 around the other corner of the same land. A secondary boat 7 and a tank boat 9 are formed across the formed second pressure control section 8, and when the secondary pressure P2 acting on the pilot chamber 10 at one end of the spool 3 becomes smaller than the force of the spring 11, 1. The opening degree of the second pressure control section 5 is increased to increase the value of the secondary pressure P2, and the secondary pressure P2 is thicker than the force of the spring 11 (if it becomes too large, the opening degree of the second pressure control section 8 is increased. The secondary pressure P2 is then kept at the same value as the force of the spring 11 by reducing the value of the secondary pressure P2.

(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 in the same centrifugal direction in a trumpet shape, 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, so it is a pinched flow. It has been confirmed that in these two types of flow, the pinched flow has a negative damping length and generates energy that increases the vibrations of the spool 3 compared to the divergent flow that has 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, the above-mentioned pinched flow makes the spool extremely unstable, causing noise due to vibration, and the guide valve 3. This has the drawback of making the movable valve 12 unstable and causing the flow rate to the actuator 13 to fluctuate.

In view of the above points, an object of the present invention is to provide a pressure control valve in which the spool is stabilized by making the first pressure control part and the second pressure control part respectively expand and flow. We have further improved the pressure control valve to prevent the control equipment from sticking and to achieve high responsiveness.

(Means for Solving the Problems) Therefore, the pressure control valve of the present invention has a secondary boat, a tank boat, and two secondary boats, and a spool is slidably disposed within the housing. In the pressure control valve that switches and connects the secondary boat to each secondary boat by moving a pair of lands provided on the spool, the flow from the secondary port to one of the secondary boats is controlled. A first pressure control section formed at the corner of one end surface of the one land spreads the flow, and a pilot chamber communicates with the secondary bow I and is formed between the other end surface of the land and the housing. The flow from the tank bow 1- to the tank bow 1- is configured to spread out at a second pressure control section formed at the corner of the other end surface of the land, and a pressure adjustment element is provided on the opposite side of the pilot chamber 1- of the spool. , For the flow from the primary boat to the other secondary boat, a first pressure control section, a pilot chamber, a second pressure control section, and a pressure adjustment element are provided in the same manner as above, and the first pressure of the one above is adjusted. When the control section and the second pressure control section are performing a control action, the other first pressure control section is closed and the secondary boat closed by the first pressure control section is communicated with the tank boat. It's Nishide.

(Function) As described above, since the fluid flows through both the first pressure control section and the second pressure control section into a spreading flow with a positive damping length, a pinched flow with a negative damping length occurs in the spool as in the conventional case. There is no effect, and it is possible to ensure the stability of the spool.

(Example) Next, regarding a specific example of the pressure control valve of this invention,
This will be explained in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, and this pressure control valve is a four-boat type pressure control valve having a secondary boat P, a tank boat T, and two secondary boats/IB. A spool 23 is slidably disposed within a valve chamber 22 formed within the housing 21. This spool 2
3 has four lands 24, 25, 26, 27, but the one set of lands 24, 25 on the left in the figure is for controlling the fluid of secondary boat A, and the one on the right A set of lands 2G and 27 are for controlling the fluid in the secondary bow 1-B. The lands 24.27 located at both ends of the above are designed to fit into pilot chambers 28.29 formed at both ends within the housing 21, and each of the above-mentioned biloft chambers 28.29 is provided with a A spring 30.31 is arranged. That is, each spring 30.3I is arranged to oppose the fluid pressure introduced into the pilot chamber 29.28 located on the opposite side. A pair of lands 25.2G at the center of the spool 23 connect the primary boat P to each secondary boat A.
. In other words, the distance between both lands is 25.26! 111tL1,
This means that the thickness L2 of the partition wall that partitions the secondary bow 1-Δ,B is smaller than the thickness L2. As a result, when the secondary boat P is communicating with one of the secondary boats A or B, the other secondary boat B or A is closed by the land 26 or 25. In addition, in the state where the primary boat P is connected to one boat A or B as described above,
A first pressure control section 32.33 is formed between the periphery of the inner corner of the land 25 or 2G and the inner wall of the housing.

On the other hand, each of the pilot chambers 28.29 communicates with each of the secondary bows 1-A and B through a passage 34.35, and a throttle 36.37 is interposed in this passage 34.35. There is. The function of the apertures 36 and 37 will be described later. A pair of large diameter portions 38,39 are also formed within the housing 21, and these large diameter portions 38,39 can communicate with each of the pyro chambers 28,29. That is, when the lands 24.27 provided at both ends of the spool 23 are located in the bicon 1-chamber 28.29, although the pilot chamber 28.29 and the large-diameter portion 38.39 are cut off, The outer end of the land 24.27 is the pilot chamber 28.2.
9, the fluid in the biloft chamber 28.29 flows through the second pressure control section 40.41 formed between the outer corner of each land 24.27 and the inner wall of the housing 21. This means that it can communicate with the large diameter portions 38 and 39. Note that each of the large diameter portions 38 and 39 communicates with the tank boat T. Further, the relationship between each of the large diameter portions 38 and 39 and the secondary bows A and 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 attached to the partition wall separating the large diameter section 38 and the secondary boat A by a predetermined distance li+, 3. Just make a kiss between the two of them.
It is a relationship that can be severed. At this time, the other first pressure control section 32 is closed as described above, but the overlap described above is opened at the outer end of this land 26, and the secondary bow 1B is It communicates with the large diameter portion 39 and is open to the tank boat T.

In addition, the first pressure control section 32, 33 and the second pressure control section 4
The relationship with 0.41 is as follows. That is, the distance % Ilt l-4 between the ends of the lands 24, z5 and 26.27 forming the first pressure control part 32.33 and the second pressure control part 40.4I on the spool 23 side, and the distance % Ilt l-4 on the housing 21 side. The distance 145 between the inner walls forming the first pressure control section 32.33 and the second pressure control section 40.41 is the same. That is, the moment the first pressure control part 32.33 opens, the second pressure control part 40.41 closes, while the moment the first pressure control part 32.33 closes, the second pressure control part 40.
．． The relationship is such that 41 is open.

In the figure, reference numeral 42.43 indicates a tension rod, and the spring force of the spring 30.31 is adjusted by this tension rod 42.43. Further, numeral 44 represents a three-position guide valve, and numeral 45 represents an actuator connected to the guide valve 44.

Next, the operating state of the pressure control valve will be explained.
The following explanation will be made regarding the case where the fluid is controlled in one of the secondary bows A). Note that the same control as described below is also performed at the other port B.

First, the spring force of the spring 31 is increased by operating the threaded rod 43 on the right side (and the spool 23 moves to the left to close the second pressure control section 40 and open the first pressure control section 32.

Therefore, in the first pressure control section 32, a spreading flow is generated from the primary boat P in the direction of the secondary port A, as shown by the arrow, and the secondary pressure P2 is raised by 2. When this secondary pressure P2 becomes larger than the force of the spring 31, the spool 23 moves to the right, contrary to the above, and the first pressure control section 32 is closed.
The second pressure control section 40 is opened. Therefore, in the second pressure control section 40, a spreading flow is generated in the direction of the tank port T from the - chamber 28 as shown by the arrow, and the secondary pressure P2
decrease. As a result, the secondary pressure P2 and the spring 31
The spool 23 remains stationary so that the forces are balanced. In this case, both the warp side corner part of the first pressure control part 33 on the right side and the second pressure control part 41 are opened at an opening greater than the control range so as not to generate large resistance. The back pressure of the guide valve 44 can be eliminated using the pressure control section 4I.

The relationship between 14 and stop 15 in Figure 1 is ideally 1,
4=15, but in reality, under such conditions, the amount of leakage from the clearances in both pressure control sections 32, 40 is large, so it is desirable to make L4 slightly larger than L5.

However, if the difference between the lengths of L4 and L5 is too large, the width of the dead zone will increase according to the amount of overlap, and the response will decrease accordingly, so it is also preferable not to make the difference between L4 and L5 too large. do not have. However, when the viscosity of the fluid is high or the flow rate is high, L4 < L5 is also possible. Therefore, when the spool 23 is stationary, the 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 in the secondary boat 8. In this case, there is a leakage corresponding to the lap ML3 at the overlap portion between the secondary port A and the large diameter portion 3, 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
Even if the land has the same diameter between the two, in other words, the land 24
．． 25 may be formed into one land. The claims are intended to cover such embodiments.

As described above, the first pressure control section 32 and the second pressure control section 4
In both cases, the fluid is a spreading flow with a positive attenuation length, and as a result, the object of the present invention, that is, the stability of the spool is achieved.

In FIG. 1, the secondary pressure P2 acting on the bicon 1 chamber 28 becomes larger than the spring 31, and the spool 23
When is moved to the right by the secondary pressure P2, the throttle 36 provided in the passage 34 acts as a resistance to the flow from the secondary boat 8 toward the pilot chamber 28, reducing the displacement speed of the spool 23. Also, contrary to the above, the secondary pressure P acting on the pilot chamber 28 in FIG.
The force of spring 31 is greater than that of spool 2.
3 is moved to the left, the throttle 36 acts as a resistance to the fluid pushed back from the bilitho chamber 1-2 in the direction of the secondary bow 1-A, reducing the displacement speed of the spool 23. In this manner, the throttle 36 reduces the displacement speed of the spool 23 during control action and reduces the inertial force of the safety spool 23, so the installation of the throttle 36 stabilizes the spool.

In this example, the left and right sides are symmetrical,
Therefore, the force of the spring 30 on the left side is increased (then, in a symmetrical effect to the above, the first pressure control section 33 on the right side and the second pressure control section 41 on the same side act on the right side of the guide valve 44. The back pressure on the left side of the guide valve 44 can be eliminated by keeping the next pressure constant and widening the left overlap L3 and the second pressure control section 40. In this case as well,
The fluid at the side pressure control 33.40 is a divergent flow.

Next, FIG. 2 shows a second embodiment of the present invention. The difference in FIG. 2 from FIG. 1 is that the proportional solenoid 46.
7, the main parts of both drawings achieve the same purpose. That is, in Figure 2, each component written with the same numerical value as the code written in Figure 1 is as follows:
These components have the same functions as the components shown in FIG. In place of the pressure adjustment springs 3o and 31 shown in FIG. 1, in FIG. A feature is that the overlapping amount L3 of the land 25.26 between B and the large diameter portion 38.39 can be easily opened by demagnetizing the proportional solenoid 35. Note that in FIG. 2, detailed explanations of the components indicated by the same numerical symbols as in FIG. 1 will be omitted.

Therefore, the operation of FIG. 2 will be explained below.

The proportional solenoid 46, 47 has a characteristic of generating an attractive force proportional to the applied current value, and applies this attractive force to the spool 23 via the movable iron core 48, 49.
Since the suction force generated in the solenoids 46 and 47 corresponds to the force of the springs 3o and 31 in FIG.
The secondary pressure P2 shown in FIG. 2 is set proportionally to the suction force of the solenoids 46, 47. In other words, the secondary pressure P2 is always proportional to the current value applied to the solenoid 46,47. Moreover, the fluid passing through the first pressure control section 32, 33 and the second pressure control section 40, 41 in FIG. 2 are both spreading flows as in FIG.
becomes stable as explained in connection with FIG.

Therefore, the features of the second embodiment of the present invention will be explained.

That is, in a control device operated by the pressure control valve, for example, the guide valve 44 shown in FIG. Consideration must be taken to prevent the spool from sticking by applying vibration to the spool. In this regard, in this embodiment, the proportional solenoids 4G and 47 apply electrical dither to the spool 23 to vary the secondary pressure little by little, thereby eliminating the sticking phenomenon of the guide valve. In particular, the idea of adding electric dither using a solenoid to eliminate the sticking phenomenon to a pressure control valve that inherently has an unstable spool, such as the conventional product, would make the pressure control valve itself extremely unstable. Although the control accuracy decreases even if the sticking phenomenon is eliminated, the second embodiment of the present invention
Since the spool 23 is stabilized in advance by the spreading flow at 1, the spool 23 does not become unstable as in conventional products (electrical dither is used to eliminate the sticking phenomenon of controlled devices such as guide valves). There is an advantage that it can be done.

Further, in this embodiment, the lands for controlling the fluid in one secondary bow 1-A or B always consist of two lands 24.25 and 26.27, and the overlapping lands 1,
3 does not open during control unless there is an excessive pressure change, but it is easy to open when the proportional solenoid 46 is demagnetized to eliminate the pressing force of the spool 23. The possibility that the Opara knob 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, each time the proportional solenoid 46 is demagnetized, the distance between the secondary boat B and the tank boat T is between the secondary pressure control section 41 and the left corner of the middle land 26, as shown by the dotted arrow in the right half of the figure. Since they communicate with each other through their surroundings, the secondary pressure P2 can be rapidly released to atmospheric pressure. Consequently, this embodiment has the advantage of being able to operate the equipment connected to the secondary boats A, B remotely and with high response via the proportional solenoids 46, 47.

Further, in any of the above embodiments, the spool 23 moves from the neutral position, and, for example, one of the first pressure control parts 32
is slightly opened, the other second pressure control section 41 is wide open, that is, one of the first pressure control sections 3
If the opening degree of the other second pressure control section 41 is always larger than the opening degree of the second pressure control section 2, the second pressure control section 41 is opened from the pilot room 29 to the tank boat T. Since there is no word acting as a fluid flow resistance, it is possible to further improve the responsiveness of the spool of the guide valve 44.

(Effects of the Invention) As described above, the present invention closes the part corresponding to the conventional second pressure control part in the constant secondary pressure pressure control valve so as not to open during control, and instead A second pressure control section 40.41 is formed between the pilot chamber 28.29 at one end of the spool and the tank boat T around the land corner at one end. Therefore, in the first pressure control section 32.33, the flow is spread out as in the conventional example, and especially in the second pressure control section 40.41, which was the conventional pinched flow, the flow is spread out, and the spool 23
Since the pinched flow that makes the spool unstable is eliminated, 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.

In addition, the proportional solenoid 4 is used as a pressure regulating element in the above.
6.47 is provided, and the solenoid 46.47 applies electrical dither to the spool to eliminate the sticking phenomenon of the controlled equipment controlled by the pressure control valve.
Since dither is added to the essentially stable spool, it has the effect of eliminating the sticking phenomenon without making the spool too unstable.

Furthermore, at the opposite corner of the first pressure control section 32, 33 in the above, the secondary boat A=B and the large diameter section 38
．． If the overlap L3 of the land 25.26 between the land 25.26 and the There are effects that can be manipulated.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view showing the second embodiment, and FIG. 3 is an explanatory diagram of a conventional example. 21...To housing 23...Spool, 24.2
5.26.27...Land, 28.29...Pilot room, 30.31...Spring, 32.33...
・First pressure control section, 40.41... second pressure control section,
46.47... Proportional solenoid, P... -Next boat, Δ, B... Secondary boat, T... Tank boat. Patent applicant Daikin Industries, Ltd.

Claims (1)

[Claims] 1.-order boat CP), tank boat (T), and 2
housing (
A spool (23) is slidably arranged in the spool (21), and a pair of lands (25) (25) are provided on the spool (23).
6) in the pressure control valve that switches the communication of the secondary boat (P) to each of the secondary boats (A) and (B) by moving the secondary port (P) to one of the secondary boats (A). For the flow, direct the flow to one of the lands (25
) A first pressure control portion (32) formed at the corner of one end surface.
, while the secondary bow) (A
) and is formed between the other end surface of the land (25) and the housing (21) to direct the flow from the pilot chamber (28) to the tank boat (T) to the corner of the other end surface of the land (25). The second pressure control section (40) formed in the second pressure control section (40) is configured to spread out the flow, and a pressure adjustment element (30) is provided on the opposite side of the viroft chamber in the spool (23), while The other secondary boat (B)
Similarly to the above, the first pressure control section (33
), pilot chamber (29), second pressure control section (41
) and a pressure adjustment element (31), and when the one first pressure control section (32) and the second pressure control section (40) are performing a control action, the other first pressure control section (32) and the second pressure control section (40) A pressure control valve characterized in that it closes the first pressure control section (33) and communicates the secondary boat (B), which is closed by the first pressure control section (33), with the tank boat (T). 2. Each of the above pressure adjustment elements is a spring (30) (31
) The pressure control valve according to claim 1, characterized in that: 3. Each pressure adjustment element above is a proportional solenoid (46')
(47) The pressure control valve according to claim 1, characterized in that: (47). 4. Each land (25) (26) above is 2(I
Land of M (24) (25) and (26) (27)
a corner opposite to the first pressure control section (32) (33) in the land (25) (26);
The amount of overlap (L3) between the secondary boat (A) (B) and the tank boat (T) with the corner on the main body side can be opened when the proportional solenoid (46) (47) is demagnetized. The pressure control valve according to claim 3, characterized in that: