DE2126763A1 - Hydraulic control valve - Google Patents

Description

* "^ ys, VV. Samliz

^T el. 5 38G5 "

Coles Cranes Limited

Crown Works

Sunderland, County Durham

England May 27th 1971

Lawyer File M-1634

Hydraulic control valve

The invention relates to a hydraulic control valve with a housing which has a first supply connection for connection to a Servomotor and a second supply port for connection with having a main control valve.

When controlling hydraulic servomotors with a downstream Load, it is common to provide a brake valve to prevent the servomotor from running away under the action of the load. The brake valve can be arranged as a check valve or compensating valve in the return line from the servomotor and can either be operated directly or from a remote location can be controlled.

Have the direct operated check or equalizing valves the disadvantage that they must be set to a sufficiently high pressure to prevent the servomotor from going through the maximum To prevent load, which in turn high pressures are necessary to drive the non-loaded servomotor.

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By remote control driven compensating valves gewöhn-- ¹ are lent for security of the supply line for the actuating motor in each direction of motion controlled. This ensures that a certain pressure is always necessary to move the servomotor in the direction of the load, and that a drop in this control pressure would prevent actuation. The control pressure can be small compared to the pressure generated by the load and depends on the design of the valve. Often devices are also provided by which the required control pressure is automatically increased or decreased with the size of the subsequent load, in order to achieve an adjustment to the particular application.

For special applications, for example with the boom cylinders of a boom crane requires the safety that the control pressure for a compensating valve located in the one supply line removed from the opposite supply line is, as mentioned above, so that if the pressure drops, the load will not run away.

One of the disadvantages of this arrangement is that in the control of the valve described above the pressure increase of the control pressure, which is necessary to open the valve, suddenly drops when the servomotor begins to move under the action of the load. This closes the valve until the pressure builds up again to release. Open this; and closing the equalization valve is commonly called "flutter" and in some cases there are devices in the valve designed to keep this flutter to a minimum,

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• for example by having a throttle opening for damping the »movement of the control valve piston.

In certain applications, valves are required that have a Can absorb significant flow and still in. The situation are able to steer very small rivers without fluttering. This problem is greatest when small, flow rates are controlled should, since the movement of the Syteuerkolbens is small and the Flow to and from the piston is also small, so that a Damping the movement is difficult to achieve.

The invention is therefore based on the object of providing an auxiliary-controlled Valve for controlling the flow of a servomotor with a subsequent load, for example for moving crane outriggers, for use in hoists and for performing telescopic movements, with the main valve controlled open is * / and is designed so that the above-mentioned problem is so small How? is kept possible. ·

A hydraulic control valve is therefore in accordance with the invention

characterized in that the first connection / the second connection in the interior of the housing via at least one flow opening is in connection, the flow cross section of which αμΓσΙι a against it slidable control member is determined by a change a control pressure actuatable and between a first position in which it completely closes the flow opening, and one second position is movable in which there is the flow opening or leaves the flow openings completely open. ·

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In a preferred embodiment, the hydraulic control valve is s shape designed so that the increase in the effective Euireh flow cross-section with increasing movement of the tax rate into the second Position grows.

The control valve may am.s a sliding sleeve ¹ in a spool, consist "The Siteuerschieber noarmaJLerweise is closed in its. Position biased by a spring, and control flow openings are arranged in the sleeve, which is controlled in such a way that a considerable part of the total stroke of the control ^{slide compared to 1 is} there. Sleeve is necessary to control small flow rates through the valve while still allowing large flow rates to pass without excessive movement of the valve slide. The valve is designed in such a way that the increase in the flow area of the flow channel, which is relieved by the movement of the control slide , while the initial movement of the control slide is small and increases with increasing movement of the control slide.

It should be noted that the effective cross section of the flow openings through the shape of boreholes and / or mouths with special shape in the sleeve is controlled, whose "size, grows increasingly as they are released from the valve spool. The holes or mouths can also optionally be in be arranged on the control slide.

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A larger diameter section can be at one end of the Valve control member may be provided, this section forming an annular chamber which extends around the control member in the main housing of the valve extends and with a supply connection for the remote control, der.in dem. Main body is provided in conjunction stands. ■

This large initial movement of the spool leading to the release a relatively small flow cross-section is necessary simplifies the damping of valve flutter. The damping opening can either be in the supply line for the control pressure or be arranged so that the fluid is behind the valve is pushed through it when opening.

The control slide and the sleeve can be of an annular inflow chamber be surrounded in the main body of the valve, the first connection with the inflow chamber and the second connection with the control spool is in communication.

Often with this type of valve it is required that a free flow can be done in the opposite direction. A separate bypass valve is used for this in some cases. It however, it is difficult to use such a valve in known valve constructions to be provided and yet to keep the low pressure loss within narrow limits. In the valve according to the invention it is possible to close the main iron valve with a small one-way valve ·. open, which opens in the direction of free flow. The interior of the housing and the valve spool can be a bypass chamber form that through a one-way valve to the inflow chamber

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is connected, wherein the one-way valve the fluid channels u; from the inflow canal to the tributary chamber closes. ■ "" '": v-

The throttle orifice can be provided in the bore of the valve slide be. An embodiment of the invention will now be based on described in the accompanying drawing. Show it:

1 shows an axial section through a valve according to the invention; Figure 2 is an end view, partially in section, of the valve;

Fig. 3 is a circuit diagram showing a possible use of the valve according to the invention is shown; and

Fig. F is a graphical representation of a valve characteristic, which can be achieved with the valve according to the invention:

The housing of the valve has a main supply port 12 from a servomotor and a supply connection 2 6 to the main control valve. A sleeve 2 is held in a housing 1 by an end cap 3. A control member in the form of a slide 4 j is slidably mounted in the sleeve 2. The slide is turned into a

closed position biased by a spring 5 «The slide and the sleeve are of an annular shape, from the supply; Connection 12 fed inflow chamber surrounded. The one in sleeve 2! included openings 6 for controlling the flow are so / j

i arranged that the increase in the effective flow area, i

which is released by the slider is initially small:

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"and- with" increasing movement of the slide into its complete open position. The diameters of the slide 4 are like this provided that the diameter 13 is larger than the diameter 14, so that an annular chamber 8 for actuation by an about before orifice 7 supplied control pressure is formed.

A small one-way valve 11 has a seat 15 on the _s is normally closed by a valve cone or a sphere 16 and a spring. This one-way valve device is held in place by a plug 18. Channels 19 allow the fluid, for example oil, to flow from a bypass chamber 9 in the housing 1 through the one-way valve 11 to the supply port 12, while the one-way valve blocks flow in the reverse direction.

An end cap 2ο and a seal 21 prevent fluid leaks into the atmosphere. The end cap 2ο also serves as a seat for a spring 5. A locking piece 22 is provided, unPderi channel between the chamber 9 and the one-way valve H against to seal the atmosphere. The chamber 9 is at one end by a seal 23 and at the other end by the seal 21 sealed in the end cap 2ο.

The annular chamber 8 is at one end through the seal 2 3 in the Slide 4 and the other end through the snug fit of the diameter 14 sealed in the sleeve 2. A seal 24 prevents one ■ Leak flow from the annular chamber 8 to the port 12, while a Seal 25 prevents leakage from ports 12 and 26 to the atmosphere. A leakage flow from the port 12 to the

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Connection 2 6 is made by the snug fit of the slide 4 in the sleeve 2 at 2 7 prevented. - -.

Operating mode . "

The valve is connected to a servomotor generally as shown in FIG. 3, which can be a hydraulic lifting cylinder or some other device in which the speed of a subsequent load is controlled by throttling the fluid exiting the servomotor. The pressure generated by the load is transmitted from the servomotor to the connection 12 and cannot be relieved because the flow control openings 6 are covered by the slide 4. If the servomotor is to be moved in the direction of the force acting on it from the outside, pressure is applied to the top of the servomotor, which acts in the direction of the force, and at the same time the control connection 7 and therefore the annular chamber 8 is supplied with a control pressure. The pressure acts on the slide 4 and moves it against the action of the spring 5. * · " ^: "

As the slide moves, there are increasing openings 6 in the sleeve 2 so that fluid flow from the port 12 to the connection 2 6 and from there to the control valve can. The openings 6 in the sleeve 2 are arranged so " that with a significant initial movement of the slide only a small increase in the flow cross section takes place ".

The brake pressure in the port 12 acts on the valve plug · or the ball 1-6 in the one-way valve "-M ₃ -: ^to; 3as valve overall '-' ■ keep closed". Therefore, if de'-r ⁷ · slide ¥ in-the * ■ ■ - _: ·

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moves open position, must be behind the slide in the chamber 9 trapped fluids pass through an orifice Io that is so large> that the desired response time and damping characteristics result.

In the embodiment shown, the control pressure acts on the differential piston surface between the diameters 13 and 13 of the slide 4. It should be noted, however, that the remote control can also take place via a separate control piston that acts on the slide 4.

The control pressure can be adjusted to a specific application in that the area of the control chamber 8 and / or the strength of the spring 5 is changed.

If remotely controlled shut-off valves are provided in the hydraulic circuit, these are usually between the servomotor and ■ the brake valve, the arrangement normally being made in this way is that the brake valve is at a higher pressure than the control pressure for the shut-off valves is opened, so that the control the load is still carried out through the brake valve. When the valve is operated in the ,, opposite direction, where a free flow is to be given, a low • pressure sets in the supply connection 26 through the damping opening Io and through the one-way valve 11. In this case, the • one-way valve opens because the pressure in port 2 6 is necessary is slightly higher than the pressure in the port 12. Flow through the orifice Io leads to a pressure drop across the •. - Io -

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- Io -

Muzzle, which acts on the full surface of the slide 4 and the Slide against the action of the spring 5 in the fully open Position moved. It should be noted that the area ratio of the slide 4 to the control chamber 8 is usually large is, so that the pressure required to overcome the spring 5 in the direction of free flow compared to the control pressure is small, which is necessary to open the valve in the opposite control direction.

If the pressure in the connections 12 and 26 is high, for example when there is a heavy load on the servomotor, this pressure load acts on the chamber in a direction in which the pressure of the spring 5 also acts, so that the pressure between the connections 26 and 12, the pressure difference necessary to open the valve in the direction of free flow is increased. This increase in the pressure difference can be overcome in that a line is provided between the control connection 7 and the connection 26 which contains a one-way valve which opens in the direction of the control connection 7. A throttle point is then provided in the line to the control connection 7 on the control pressure side of the connection with this line in order to generate a pressure increase from the connection 26 for the mode of operation with ^: free flow.

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Claims (1)

2126783 - ii - Coles Cranes Limited Crown Works SunderTand, County Durham ■ -..- ■ -. England ■ May 27, 1971 Lawyer File M-16 Claims Hydraulic control valve with. a housing having a first supply port for connection to a servomotor and a second supply port for connection to a main control valve has, characterized in that der.erste connection (12) with the second connection (26) in the interior of the housing (1) via at least one flow opening (6) in connection stands, whose flow cross-section is determined by a displaceable control member (4), which is by a Change of the control pressure actuated and between a first Position in which the flow opening (6) is completely. closes, and a second position is movable in which it the flow opening (6) or the flow openings completely leaves open. ■ ' 2. Control valve according to claim 1, characterized in that the Increase in the effective flow cross-section of the flow opening (6) grows with increasing movement of the control member (4) into the second position. 3. Control valve according to claim 1, characterized in that the 109850713U " ¹² ' (4) is: the one in one. Sleeve C2-) g hegz, gelagerrfc; iSiC and dx ^ ch '/ a spring: (5> pretensioned in the closed position; is :. _; ■. V- · Control valve. according to / claim: 2 ·, characterized ·} that.-a. From &<3hn; | 1 ;; f. '(L3 ;,} with; ^ ößeremer Direliinesser / at one end of the Sehiebeass Cu ^ is provided ^ and; that .d * er ^ Abselonitt. - ■ forms this around the; Slide .C * l ·) i housing CD of the valve runs, and that a control connection in the housing (1) is in connection with the annular chamber (8). . Control valve according to claim 2 or 3, characterized that the slide iA) and the sleeve (2) from an annular r in the case, and that he.s ^ te with the inlet chamber and the second connection mi1 | _ (%> is connected; .. 6 ;, S ^ & uerveniiil according to claim, M- , characterized in that; the Bohruificg this slide Cf) a Brosselsielie 7. ^ uepv) ent: il according to claim 4 or 5, characterized ;, that the inside of the housing and the slide (4) one Form tributary chambers, which via a one-way valve (15, 160> with the inflow chamber (12); is connected, and that that. A-r way valve the. Flow of fluid from the inflow * Chamber to the tributary chamber * locks - 13.- - 8. Control valve according to one of the preceding claims, characterized characterized that control flow openings in the sleeve C2) are provided. 9. Control valve according to one of the preceding claims, characterized in that the size of the control flow openings progressively increases in the direction in which they are progressively released by the slide (4). 109 8 50/1314 L.iif., ..