EP1510699B1 - Method and device for switching a fluid flow - Google Patents

Abstract

The method involves advancing two sliders (2) independently of each other during a time interval of a switchover from a pump (40) into a hydraulic line or a reservoir using a three-way valve (8). An axial motion of the sliders is initiated in the valve by a rise and drop of a pilot pressure in the valve. A quantity of oil in the sliders is directed in a predetermined direction during switchover. An independent claim is also included for a fluid device.

Description

The invention relates to a method and apparatus for rapid switching of a liquid or gaseous medium in a hydraulic or pneumatic route by means of a pump depending on the pilot pressure either in a reservoir or in the hydraulic / pneumatic route using a switching valve.
The control of, for example, an oil flow in a hydraulic path takes place primarily via at least one pump, the direction and the flow rate of which are arranged in the hydraulic path, correspondingly pilot operated valves. A balance of hydraulic amount is realized via a reservoir, so that corresponding valves or valve assemblies are provided to realize a flood switch from the pump either in the hydraulic route or in the reservoir, such as from EP-A-1 279 870 is known.

Thus, for example, it is customary to use a check valve with a parallel throttle section, wherein a correspondingly constructive throttle insert operates in this throttle section as a flow regulator. Furthermore, a plurality of valves of different function, such as a non-return and a relief valve function, are coupled together as a pilot-operated pressure control valve with a check valve. Here, the spring chamber of the pressure regulating piston is connected via a further throttle bore in the pressure regulating piston itself with a pressure or pump connection. If the static pressure rises above the set value of the pressure valve, it is opened, allowing hydraulic fluid to drain to the reservoir. This drain creates a pressure drop in the spring chamber of the pressure regulating piston, whereby the closing force of the spring is released and the pressure regulating piston of the check valve opens the way to the reservoir.

For this solution, however, several individual valves are needed, which on the one hand is technically complex and on the other hand requires a corresponding space requirement.

A more elegant solution of the flood switching or the control of the pressure medium paths is in the DE 37 23 672 C2 This technique is technically implemented in a valve unit by combining the functions of several valves. Here, a valve is placed between two housing connections. The housing of the valve is provided with two spring-loaded slide-like closure pieces, which are mutually displaceable in the valve bore. In this case, the guided in a housing bore plug cooperates with a housing-fixed valve seat. Both spring chambers of the closure pieces are in communication with each other. The first, acting as a valve spool closure piece, is used to control at least one control terminal, which is connected to a pressure relief valve. If the valve spool is subjected to a pressure which is higher than the two spring forces in the spring chambers, the valve spool lifts from its valve seat fixed to the housing and closes the control port. The other closure piece works as a pressure regulating piston and communicates with the other housing-side connections, which are released or opened during this process accordingly.

However, this process of flood switch requires a certain amount of time. Thus, the valve spool covers during the switching for a certain time a defined area in the housing, which must be technical, so that the hydraulic route can not be connected directly to the reservoir. In the phase where the valve spool covers the housing-side connections to the hydraulic line and to the pump, the pressure that builds up before the pump is limited by the pressure relief valve, which is located between the hydraulic section and the pump.

Instead of a pressure relief valve and the use of a check valve is known. However, using a check valve does not guarantee that it will work reliably. If the pilot pressure rises, it opens. If the pilot pressure drops, it responds with a time delay and oil can now flow into both the hydraulic line and in the reservoir.

The object of the invention is to switch the fluid from a pump pilot pressure dependent in different line connections so that the time required for this purpose shortened and the switching is realized by means of only one valve while the size of the valve undergoes only an insignificant change.

According to the invention, this object is initially achieved in that the slide has a first slide element and a second slide element, which are accelerated independently of each other at least during a time interval of the switching process. This acceleration serves to shorten the switching process in order to reduce the pressure increase occurring during the switching before the pump as quickly as possible, which u. a. extends the life of the pump.

The advantage here is to allow the fluid switching of a pump either in a fluidic path or in a reservoir by means of a pilot-pressure-dependent three-way valve to take place without having to use an additional check valve

Advantageously, the axial movement of the slide in the valve is superimposed on a further axial movement, resulting in a resulting movement, which is the result of the addition of equal and opposite forces, these forces acting simultaneously or with a time delay on the slide during the switching operation.

It is particularly advantageous to store in the slide a defined amount of oil which is steerable during the switching in the predetermined direction

To realize these processes and thus to achieve the object according to the invention, it is particularly advantageous that a pump is connected either to a fluidic path or to a reservoir by means of a pilot-pressure-dependent three-way valve. which contains a two-part slide with a first slide element and a second slide element and that the housing of the valve has further connections to the pump, which connect to the existing connections in the axial direction and are spaced from both these and from each other.

In a further advantageous embodiment of the invention decreases after the second further pump connection in the direction of compression spring, the wall thickness of the housing like a paragraph and remains the same for the rest of the housing part. The resulting at the shoulder radial annular surface also forms the abutment surface for the slider guided in the housing.

Furthermore, the object is achieved in that the slide has an incision in front of its pressure spring end, which reaches the diameter of the slide again in two correspondingly wide steps in the direction of this end and with a further outermost stage adapts to the inner diameter of the housing. This step-like design of the incision has the advantage that simultaneously defined stops can be realized in this way. Thus, the structural design of the housing suggests that the radial annular surface created by the outermost step of the slide forms the return surface and advantageously limits the travel of the pressure spring with the stop surface.

Advantageously, the slide is provided in the radial direction with a centrally arranged through hole The diameter of this hole is equal to the diameter of the two additional pump connections to choose to establish a secure connection between the pump and slide can and to achieve no pressure losses.

Furthermore, it is advantageous to choose the distance of the through hole of the pressing surface so that at the time when the groove of the slider is in the overlap region, the slide is connected via this through hole with the additional left pump port.

In a further advantageous embodiment of the invention, starting in the slide, starting from the druckfederseitigem end, axially provided in the through-hole blind hole, in which a bolt is guided.

The holes provided in the slide, which are connected at right angles to a line, are used together with the step-like recess for receiving a defined volume of oil, which can be carried out in case of need by pressurization or pressure relief movements of components. Thus, the existing in the blind hole pin within the blind hole is moved either towards the housing wall or in the direction of drilling. It is advantageous that it has a certain length in order to be able to center also for the slide in the housing.

A further advantageous embodiment of the invention provides that functionally, the width of the innermost stage of the incision is defined by the distance between the outer wall of the diameter of the through hole to the shoulder of the subsequent second stage and the width of the second stage of the sum of the diameter the two additional pump connections and their distance from each other.

Furthermore, it is advantageous that the width of the second stage of the incision adjoins that of the innermost and goes beyond the heel-like reduction of the wall thickness of the housing. Thus, an additional pressure chamber is formed, which also serves to influence the axial movement of the slide.

It is also advantageous that a sliding ring is applied to the innermost stage of the incision, which can move axially on this. Thus, the mass of the slider is divided into two sub-masses. The mutually operatively connected masses can thus be acted upon with different, large forces whose direction may also be different.

Furthermore, it is advantageous that the outer diameter of the sliding ring corresponds to the inner diameter of the housing, d. h., that both abut each other. This ensures that, on the one hand, the respective additional pump connection is closed and, on the other hand, the pressure built up in the second pressure chamber can not be reduced in an uncontrolled manner.

In an advantageous development of the invention, the width of the sliding ring results from the difference between the width of the innermost step width and the diameter of the connection. This ensures that an additional pump connection is always open when the sliding ring is in one of its end positions at the innermost stage.

Another advantage is that the surface roughness of the outer and inner diameter of the sliding ring is different. It is particularly advantageous if the roughness of the surface at the outer diameter of the sliding ring is higher than at the inner diameter. As a result, a static friction between the surface of the sliding ring and the surface of the inner diameter of the housing is achieved, which is exploited to achieve a delay in reversing the direction of movement of the slider.

Moreover, it is advantageous if the slider and sliding ring is made of metallic material. However, both can equally well consist of non-metallic material and plastic material. Likewise, the two components may have different materials. This depends on the particular application.

The device will be explained in more detail using an exemplary embodiment, wherein the embodiments relate to a hydraulic path.

Fig. 1:

eine prinzipielle Darstellung der erfindungsgemäßen Lösung in einer hydraulischen Strecke

Fig. 2 - 5:

die Wirkungsweise des erfindungsgemäßen Umschaltventils bei unterschiedlichen Vorsteuerdrücken.

Show it:

Fig. 1:

a schematic representation of the solution according to the invention in a hydraulic route

Fig. 2 - 5:

the operation of the changeover valve according to the invention at different pilot pressures.

From the Fig. 1 is the basic structure and operation of the invention in a hydraulic route visible. A switching valve in the form of a three-way valve, which is connected via two connections to a module, is acted upon by a control, not shown, with a pilot pressure, which is performed by a piston. As a result, the closure member or slide present in the valve is moved so that the desired lines are connected to each other.

According to Fig. 1 is essentially a connection from the pump to the hydraulic path recognizable, which is interrupted by the closing body of the valve at falling pilot pressure to make the connection hydraulic route - reservoir. Until the switchover to another connection, whereby the deflection of the hydraulic flow is simultaneously achieved, the slide in the valve housing covers a certain area, so that in this connection to two ports can not be produced, but always a housing connection is closed. However, this overlap area is technically conditioned to exclude a connection of the hydraulic route to the reservoir. To meet this technical requirement, however, to shorten the switching time, the coupled with the valve assembly whose operation is based on the FIGS. 2 to 4 will be described in more detail.

From the FIGS. 2 to 4 , each representing the arrangement of the solution according to the invention, the operation of the changeover valve will be apparent.

The valve 8, consisting essentially of a housing 1 and a slide 2, which is held by a compression spring 11 in a certain position, inter alia. The housing 1, whose wall thickness is reduced step-like to form a paragraph pressure spring side, has 6 holes or connection options for corresponding lines. In this case, a connection for the introduction of hydraulic oil for acting on the pressing surface 14 of the slider 2 with a certain pressure, the pilot pressure is used. The further holes are provided for connections to a pump 4, 4a and 4b, to a reservoir 5 and to the hydraulic path 6.

The slider 2 is provided at a distance from the pressing surface 14 with a circumferential groove 7, the width of which results from the distance between two adjacent ports plus their diameter. This ensures that the groove 7 in the axial movement of the slider 2 in each case two of the adjacent terminals 6, 4, 5, the distance between the groove 7 of the pressing surface 14 depends on the stop of the slider 2 on the housing 1, resulting from the Impact of the return surface 12 of the slider 2 on the stop surface 9 of the housing 1 results.

For the realization of further pump connections, the connections 4a and 4b are provided in the housing 1 of the valve 8. To control the possibility of connecting either the connection 4a or the connection 4b to the pump is released, the slider 2 has a radial incision 10, which tapers the diameter of the slide 2 to a specific diameter. This is maintained in the axial direction over a certain length until the original diameter of the slider 2 is reached again via the adjoining step. Another in continuation of the slide 2 subsequent stage whose diameter is greater than its original diameter, is used with the housing 1 to form a stop. In addition, the slider 2 is provided in the radial direction with a centrally disposed through hole 13 which penetrates the incision 10 at two points of the circumference and this affects it with its outer wall. Advantageously, the diameter of this bore 13 is equal to that of the terminals 4a and 4b. The slide 2 is further provided with an axially central blind hole 17 which, starting from the druckfederseitigem end, with the through hole 13 coincides. In this Grundlochbohrung a bolt 18 is arranged, which is used to center the Slider 2 on the inner wall of the housing 1 is supported. Furthermore, the two holes 13 and 17 are filled with hydraulic fluid.

The innermost step of the recess 10 serves to receive a sliding ring 16, which is within the limit of the stage, d. H. from the outer wall of the through hole 13 to the subsequent step, is axially movable. This sliding ring 16 has an outer diameter which is adapted to the inner diameter of the housing 1 at this point. Its width is defined by the distance of the terminals 4a and 4b from each other plus the diameter of one of these ports, both diameters, due to their function, are the same size. Furthermore, the surface of the sliding ring 16 is roughened on the outer circumference, so that although it is axially movable on the slider 2, but always a certain static friction is ensured to the inner wall of the housing 1.

For applying the sliding ring 16 to the innermost stage of the incision 10, it is advantageous to either divide the slide at the point where the subsequent step begins, or to maintain and thread the diameter of the innermost step as an extension to its end , The further stepped portion of the slider 2, which has a corresponding internal thread, can then be screwed to the first portion. There are also other ways of connecting both sections conceivable, such. Another solution to the problem would be to divide the sliding ring 16 into at least two parts, which would then have to be reassembled after application to the innermost step ,

For the solution of the object according to the invention, the arrangement and design of the incision 10 is of particular importance. Is the circumferential groove 7 in the region of the housing 1, where only the terminal 4 remains open, the bore 4a must be congruent with the through hole 13. The incision 10 adjoining the through-hole in this illustration has, as already mentioned, two stages, wherein the width of the innermost stage is so great that it forms the two connections 4a and 4b and their space covered. The subsequent step must be so wide that it extends beyond the shoulder of the housing 1, so that in conjunction with the outermost stage in this position of the slide 2, a second pressure chamber 20 is provided. The two bores 13 and 17 together form the third pressure chamber 21.

According to Fig. 2 the slide 2 is in the vicinity of the left inner wall of the housing 1 of the valve 8. A suitably dimensioned centrally mounted on the inner wall spacer ensures that the slider 2 is always kept at a distance from the inner wall of the housing 1, so that with a appropriate pilot pressure hydraulic fluid may be introduced into the first pressure chamber 19. Are the two forces acting on the end surfaces of the slider 2 in equilibrium, this takes the in Fig. 2 shown position, ie, the pump 4 is connected to the hydraulic path 6. Increases the pilot pressure in the first pressure chamber 19 and thus the force that is directed against the force of the compression spring 11, the equilibrium of forces is canceled within the valve 8 and the pressing against the pressing surface 14 hydraulic fluid moves the slide 2 in the direction of compression spring 11. In this axial movement reaches the circumferential groove 7 in the region of the terminals 6 and 4. The sliding ring 16, fitting to its left boundary, is moved along.

At the same time, the return surface 12 of the slider 2 lifts off from the stop surface 9 of the housing 1 and hydraulic fluid can through the port 4 b in the free space of the incision 10 and in the, directed by the two oppositely directed stages of slide 2 and housing 1, second pressure chamber 20 flow. The movement in this direction continues until the switching operation is completed, i. H. until the groove 7 of the slider 2 releases the ports 4 and 5.

In the Fig. 3 the exceeding of the overlapping area 15 by the circumferential groove 7 is shown. Until the completion of the switching operation could accumulate via the port 4b hydraulic fluid in the second pressure chamber 20, which At the same time has the advantage that the pressure that has built up by closing a pipe in front of the pump, can break down again. The hydraulic fluid in the second pressure chamber 20 causes the sliding ring 16 to continue to maintain its position.

If the switching process is complete, as shown Fig. 4 can be seen, so that the terminals 4 and 5 are connected to each other, the slider 2 has moved so far in the direction of compression spring 11, that the sliding ring 16, the terminal 4b closed and at the same time the terminal 4a has opened. In the process, the hydraulic fluid in the third pressure chamber 21 has at the same time pushed the bolt 18 against the wall of the housing 1, whereby a pressure builds up, which endeavors to break down again. This pressure reduction causes the slider 2, guided by the bolt 18, is moved back to its original position. Until the time when the sliding ring 16 has reached its right stop, the terminals 4 and 5 are connected together.

Falls the pilot pressure, resulting from the Fig. 5 clearly shows the slider 2 moves back in the opposite direction. The sliding ring 16 retains, due to its increased friction, on the inner wall of the housing 1, first its position. A pressure equalization, triggered by the third pressure chamber 21, can now take place via the connection 4a connected to the through-bore 13. During this process, only the slider 2 has moved and the sliding ring 16 has remained at its right stop. The circumferential groove 7 has now again in the overlap area. At the same time a pressure has built up by the displacement of the sliding ring 16 in the second pressure chamber 20, which also endeavors to compensate and thereby moves the sliding ring 16 back to its left stop surface. Now port 4b is open and the switching process is completed in that direction. Abbreviation List 1 casing 2 pusher 3 pressure connection 4 pump connection 4a pump connection 4b pump connection 5 Connection reservoir 6 Connection hydraulic route 7 Circumferential groove 8th Valve 9 stop surface 10 Step-like incision 11 compression spring 12 Return surface 13 Through Hole 14 pressing surface 15 Coverage area 16 sliding ring 17 Basic hole 18 bolt 19 First pressure room 20 Second pressure chamber 21 Third pressure room

Claims (25)

1. Method for releasing an outlet connection with the aid of a valve (8) which has a housing (1) with an inlet connection (3) and with a first outlet connection (6) and a second outlet connection (5), and with a slide (2) movable in the housing (1), the slide (2) having a first slide element (2) and a second slide element (16) which are accelerated independently of one another, at least during a time interval of the switching operation, furthermore the slide (2) having, before its end located on the compression-spring side, an indentation (10) which reaches the diameter of the slide (2) again in two steps of corresponding width in the direction of this end and which is adapted by means of a further outermost step to the inside diameter of the housing (1).
2. Method according to Claim 1, characterized in that fluid switching by a pump either into a fluidic zone (6) or into a reservoir (5) takes place by means of a three-way valve (8) dependent on pilot control pressure.
3. Method according to Claim 1, characterized in that a rise or fall in the pilot control pressure triggers an axial movement of the slide (2) in the valve (8), upon which a further axial movement is superposed.
4. Method according to Claims 1 to 3, characterized in that the resulting movement of the slide (2) arises from the addition of codirectional and contradirectional forces.
5. Method according to Claims 1 to 4, characterized in that the superposition of the movement of the slide (2) takes place simultaneously or with a time offset during the switching operation.
6. Method according to Claims 1 to 5, characterized in that an oil quantity stored in the slide (2) is deflectable into the predetermined direction during the switching operation.
7. Device for carrying out the method according to Claims 1 to 6, characterized in that a pump is connected either to a fluidic zone (6) or to a reservoir (5) by means of a three-way valve (8) dependent on pilot control pressure, which contains a two-part slide (2) with a first slide element (2) and with a second slide element (16).
8. Device for carrying out the method according to Claims 1 to 7, characterized in that the housing (1) of the valve (8) has further connections to the pump (4a and 4b), which are adjacent in the axial direction to the existing connections (6, 4, 5) and are spaced apart both from these and from one another.
9. Device according to Claim 8, characterized in that, after the connection (4b) on the compression-spring side, the wall thickness of the housing (1) decreases in the manner of a shoulder and remains the same for the remaining housing part, and the radial annular surface which has occurred at the shoulder forms the abutment surface (9).
10. Device according to Claim 9, characterized in that the radial annular surface formed by means of the outermost step forms the return surface (12) which with the abutment surface (9) limits the excursion of the compression spring (11).
11. Device according to Claims 1 to 10, characterized in that the slide (2) is provided in the radial direction with a centrically arranged through-bore (13), the diameter of which is identical to the diameter of the connections (4a) and (4b).
12. Device according to Claim 11, characterized in that the distance of the through-bore (13) from the press-on surface (14) is selected such that, while the groove (7) of the slide (2) is in the overlap region (15), a connection to the connection (4a) is made by the through-bore (13).
13. Device according to Claims 11 and 12, characterized in that a blind-hole bore (17) which issues into the through-bore (13) and in which a bolt (18) is guided is provided axially centrally in the slide (2), starting from that end of the latter which is on the compression-spring side.
14. Device according to Claim 13, characterized in that the bolt (18) is supported on the end face against the inner wall of the housing (1) and has a length which is smaller than or equal to that of the blind-hole bore (17).
15. Device according to one of Claims 1 to 9, characterized in that the width of the innermost step of the indentation (10) is defined by the distance between the outer wall of the diameter of the through-bore (13) and the shoulder of the adjoining second step.
16. Device according to one of Claims 1 to 9, characterized in that the width of the second step arises from the sum of the diameters of the connections (4a) and (4b) and their distance from one another.
17. Device according to one of Claims 1 to 9, characterized in that the width of the second step of the indentation (10) adjoins that of the innermost step and goes beyond the shoulder-like decrease in the wall thickness of the housing (1).
18. Device according to one of the preceding claims, characterized in that a sliding ring (16) is mounted on the innermost step of the indentation (10) and can move axially on the said step.
19. Device according to Claim 18, characterized in that the outside diameter of the sliding ring (16) corresponds to the inside diameter of the housing (1).
20. Device according to Claims 18 and 19, characterized in that the outside diameter of the sliding ring (16) forms with the inside diameter of the housing (1) a friction pairing.
21. Device according to Claims 18 to 20, characterized in that the inside diameter of the sliding ring (16) forms with the diameter of the indentation (10) a gap.
22. Device according to one of Claims 18 to 21, characterized in that the width of the sliding ring (16) arises from the difference in the width of the innermost step and the diameter of the connection (4a).
23. Device according to one of Claims 18 to 22, characterized in that the surface roughness of the outside and the inside diameter of the sliding ring (16) is different.
24. Device according to Claim 19, characterized in that the roughness of the surface of the outside diameter of the sliding ring (16) is higher than that of the inside diameter.
25. Device according to one of the preceding Claims 1 to 24, characterized in that the slide (2), sliding ring (16) and housing can be produced from metallic or non-metallic material or plastic.

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