EP3042087B1 - Valve elements - Google Patents

Description

The invention relates to a pressure compensator with the features in the preamble of claim 1.

Such pressure compensators, in particular as integral components of directional control valves, are known in various embodiments in the prior art. For example, the EP 1 500 825 A2 a pressure compensator with a valve slide which is longitudinally displaceable in a valve housing and which has a control part for controlling a fluid-carrying connection between at least two fluid connection points received in the valve housing, which has at least one pocket-like recess that is at least partially delimited by a fluid-guiding surface that at least runs between two vertices of the recess and which, starting from one vertex to the other vertex, runs with an initially increasing and then constant slope, the other vertex, which is located at the exit of the pocket-like recess, delimiting the edge or corner of a right angle as a transition between the Fluid guide surface and a transverse collar surface of the valve or control slide.

It has been found to be disadvantageous in pressure compensators of this type that, starting from the zero stroke, the course of the active standard cross section over the Opening stroke increases very steeply and has at least one kink in the further course. Because of this course of the standard cross-section over the opening stroke, the control quality and the stability of the known pressure compensators are in need of improvement in order to increase the precision of the fluid control.

Since the known directional control valves with upstream or downstream pressure compensators often have to perform a so-called load-holding function, the geometric configuration of which is usually carried out by a circumferential, vertical edge, this makes effective compensation of the flow forces more difficult.

Further valve components go from the EP 0 200 182 A2 , the DE 26 04 208 A1 , the DE 10 2010 053 805 A1 , the U.S. 4,667,930 , the JP H10-132096 , the EP 2 053 253 A2 , the DE 102 18 783 A1 , the DE 10 2009 021 831 A1 and the WO 2010/042362 A2 emerged.

Based on the prior art, the invention is based on the object of providing a pressure compensator with improved control quality and increased stability, which reacts with little delay.

This object is achieved by a pressure compensator with the features of claim 1. Advantageous embodiments of this pressure compensator emerge from the dependent claims 2 to 6.

The pressure compensator is characterized in that, starting from a predeterminable distance from the other vertex, the fluid guide surface runs from its greatest slope with a decreasing slope in the direction of the other vertex.

In this way, the pocket-like depression does not open out at one edge, but rather flows smoothly into a collar-like recess adjacent to the depression Front face of the control part as part of the valve slide. This has the advantage that the standard cross section does not change abruptly at an edge, as shown in the prior art. Therefore, the course of the standard cross-section over the opening stroke does not have a kink, but a steady, monotonically increasing standard cross-section with a very flat initial slope is implemented over the opening stroke of the valve slide with its control part, so that there is a very high control quality, especially at the beginning of the opening process, and over a relatively long opening stroke of the valve slide. The control quality is therefore considerably higher than with known solutions and the stability of the control is also improved.

Preferably, however, the fluid guide surface has a steady course and the smallest amount of slope or amount of slope, preferably assuming the value zero, at the respective other vertex. With a reversed arrangement of the vertices, however, there is the possibility of first starting with the flat slope at the bottom of the pocket and letting the fluid guide surface run outwards towards the control collar with an increasing slope. The fluid guide surface is particularly preferably designed in a curve (S-shape) and the different gradient profiles between the vertices are implemented by the transition from a concave to a convex curve profile. In principle, however, it is also conceivable that the curve shape is formed by other arc shapes, in particular semicircles. Such a rounded guide surface also contributes to a constant, "kink-free" control behavior of the valve component. In particular, two fluid guide surfaces which are adjacent to one another and which merge into one another at the bottom of the pocket form the edge-side boundary for this pocket.

In principle, however, it is also conceivable for the respective fluid guide surface to be formed by several flat surface sections arranged one behind the other is formed, each surface section preferably having a uniform slope which corresponds to the slope of the curve profile of the fluid guide surface in a central region of the respective surface section. According to a further development, the course of the fluid guide surface can also be iteratively approximated by step-like shoulders, wherein the surfaces of the shoulders can be aligned coaxially or transversely to the longitudinal axis of the valve slide.

Along the outer circumference of the control part of the valve slide, so many pocket-like depressions can advantageously be arranged that the fluid guide surfaces between the individual vertices form a closed sinusoidal or cosine-shaped curve along this outer circumference. The course of the guide surfaces is accordingly undulating. The individual depressions merge into one another without a gap.

Advantageously, at least in the case of some of the pocket-like depressions, a groove-like depression adjoins the pocket-like depression on the bottom side in the region of an apex. These groove-like depressions offer the possibility of fine-tuning the amount of fluid to be conveyed.

The largest opening cross-section of the respective pocket-like depressions is directed towards that fluid connection point which is used for the fluid outlet from the valve housing. In this way, as the opening stroke of the valve slide increases, the standard cross section can be continuously adapted to the increasing amounts of fluid.

Another valve component is characterized in that the guide part has a stepped switching edge surface which faces the first control part.

In this way, a defined trailing edge is formed at which the flow surface merges from an annular transverse surface running in the radial plane at one edge into an outer circumferential surface running coaxially to the longitudinal axis of the valve slide. The stepped switching edge surface improves the sealing function within the second valve component. With the valve component, a load holding function for a pressure compensator or a valve can be achieved with simultaneous flow force compensation, which applies to the case when the trailing edge is both flow guidance, in particular in the form of a flow cone, and a defined vertical edge.

The step-like switching edge surface running in the guide part of the second control part can be formed via a diameter reduction between the outer circumferential side of the guide part and a preferably conical transition part of the valve slide in the direction of the first control part. The conically running transition part forms a flow guide that serves to compensate for the flow force.

Another valve component is characterized in that there is a further fluid guide which keeps the second control part at a distance from the second guide part.

Such a puncture advantageously improves the flow around the second control part and facilitates the resetting of the valve slide. In addition, the sealing gap between the first guide part and the inner wall of the housing is reduced, which promotes the load-holding function of the second valve component described above.

The two fluid guides, the axial distances between the first control part and the second control part and between the second control part and the second guide part are obtained by groove-like circumferential diameter reductions in the valve slide. These diameter reductions result in a broad, free, ring-shaped cross section through which the fluid can flow with low pressure losses, which is also beneficial to rapid control behavior due to the low mass.

The valve slide can be supported on its one free end face against an energy store and on its other free end face it can be adjacent to a volume space of variable volume into which one end of an inner channel of the valve slide opens, the other end of which is connected to the fluid guide between the two control parts in a fluid-carrying manner is. In this way, the fluid pressure at the fluid inlet can be mapped efficiently on the other free end face. No further complex holes in the valve housing are required.

The combination of non-return function and flow force compensation is possible because the distance between the respective control edge and the trailing edge is sufficiently large, since otherwise a reasonably high stroke resolution of the control edge would not be able to be combined with effective flow force compensation.

Fig. 1

einen Längsschnitt durch einen Teil eines Ventils, insbesondere in der Art einer Druckwaage;

Fig. 2

eine Sicht auf eine abgewickelte Darstellung des Außenumfangs des ersten Steuerteils;

Fig. 3

eine prinzipielle Darstellung eines vergrößerten Ausschnitts aus Fig. 2;

Fig. 4 und 5

zwei Detaildarstellungen des Schaltkantenverlaufs des zweiten Steuerteils; und

Fig. 6

einen Graph, der den Verlauf des Regelquerschnittes über dem Öffnungshub des Ventilschiebers für dessen erstes Steuerteil wiedergibt.

The invention is explained in more detail below on the basis of an exemplary embodiment shown in the figures. Show it:

Fig. 1

a longitudinal section through part of a valve, in particular in the manner of a pressure compensator;

Fig. 2

a view of a developed representation of the outer periphery of the first control part;

Fig. 3

a basic representation of an enlarged section Fig. 2 ;

Figures 4 and 5

two detailed representations of the switching edge profile of the second control part; and

Fig. 6

a graph showing the course of the standard cross-section over the opening stroke of the valve slide for its first control part.

In the Fig. 1 a part of a valve construction 10, especially designed in the manner of a pressure compensator, is shown. A valve housing 12 has a valve bore 14 in which a valve slide 16 which is guided so that it can be moved longitudinally is arranged. The valve bore 14 is closed at both ends 18 by end screws 20, 22 which each engage in an assignable internal thread 24 of the valve bore 14. Annular sealing elements 26 are provided between the end screws 20, 22 and the valve housing 12.

The valve slide 16 is provided for controlling a fluid-carrying connection 28 between at least two fluid connection points 30, 32 received in the valve housing 12. The valve slide 16 has a cylindrical first control part 34, which on the outer circumference 36 has pocket-like depressions 38 running coaxially to the longitudinal axis LA of the valve slide 16 (see also FIG Fig. 2 and 3 ), which are delimited by circumferential fluid guide surfaces 40 which each run between vertices (maxima or minima) M1, M2, M3 of the recess 38 and which each proceed from a vertex M1; M2, M3 towards the other vertex M2, M3; M1 runs with increasing slope in terms of amount or with increasing slope (slope S1 = 0 <slope S2 <slope S3 <slope S4 or slope S11 = 0 <slope S12 <slope S13 <slope S14).

According to the invention it is provided that the fluid guide surface 40 from a predeterminable distance A1; A2 from the other vertex M2, M3; M1 starting from its greatest slope S4 in terms of absolute value; S14 at reversal points UP1, UP2 with decreasing slope (slope S4> slope S5> slope S6> slope S7 = 0 or slope S14> slope S15> slope S16> slope S17 = 0) in the direction of the other vertex M2, M3; M1 runs. The respective fluid guide surface 40 thus has a steady course and the smallest slope amount (S1, S7; S11, S17), preferably assuming the value zero, at the respective other vertex M2, M3; M1.

The fluid guide surface 40 is designed in the shape of a curve and the different gradients S2, S3, S4, S5, S6; S12, S13, S14, S15, S16 between the vertices M1, M2, M3 are implemented by a transition at the reversal points UP1, UP2 from a concave to a convex curve. Along the outer circumference 36 of the first control part 34 of the valve slide 16 there are so many pocket-like depressions 38 that the fluid guide surfaces 40 between the individual vertices M1, M2, M3 form a closed, cosine-shaped curve along this outer circumference 36. At every third pocket-like depression 38, a groove-like depression 50 adjoins the pocket-like depression 38 on the bottom side in the region of the apex M1. The largest opening cross-section 52 of the respective pocket-like depression 38 is directed towards that fluid connection point 32 which is used for the fluid outlet 54 from the valve housing 12. Thanks to the groove-like recess 50, the control behavior of the valve slide 16 is improved overall.

The valve slide 16 has a total of two control parts 34, 56, of which the first control part 34 has at least the pocket-like depressions 38 and the second control part 56 is arranged at a distance from the first control part 34 by a first fluid guide 58. The second control part 56 is in the unactuated state of the valve slide 16, that is to say in the zero stroke shown in the left end position in the image plane and by means of a cylindrical guide part 60 in contact with an inner wall 62 of the housing. The guide part 60 has a stepped switching edge surface 64 which faces the first control part 34. The switching edge surface 64 is formed by a diameter reduction 66 between the outer peripheral side 68 of the guide part 60 and a preferably conical transition part 70 of the valve slide 16 in the direction of the first control part 34. The conically running transition part 70 forms a flow guide for the fluid flowing through the valve component 10 and causes the fluid flow to be deflected in the direction of the fluid outlet 54. It also contributes to the flow force compensation. The transition part 70 can either be attached directly to the diameter reduction 66 ( Fig. 4 ) or via a diameter reduction 66 in the form of a recess ( Fig. 5 ) merge into the annular transverse surface to the longitudinal axis LA in the form of the switching edge surface 64, which adjoins the switching edge 72 on the outer peripheral side 68 of the cylindrical guide part 60. Through the recess 66 in Fig. 5 the switching edge area 64 is displaced downstream.

By means of a second guide part 74, the valve slide 16 is guided through its inner wall 62 in the region of the fluid connection point 32 serving the fluid outlet 54 in the valve housing 12. Between the first control part 34 and the second control part 56 there is already arranged a first fluid guide 58 keeping them at a distance. A second fluid guide 76 between the second control part 56 and the second guide part 74 now improves the flow around the valve slide 16 in the region of the second control part 56, as a result of which the pressure losses within the valve component 10 are reduced. Furthermore, the sealing behavior of the first guide part 60 with respect to the housing inner wall 62 is improved by the second fluid guide 76, since the sealing gap between the valve slide 16 and the housing inner wall 62 can be reduced by introducing the second fluid guide 76 into the valve slide 16. The two fluid guides 58, 76, which form the axial distances ASS, ASF between the first control part 34 and the second control part 56 and between the second control part 56 and the second guide part 74, are obtained by groove-like diameter reductions 78, 80 in the valve slide 16. Such diameter reductions 78, 80 are also referred to as recesses.

The valve slide 16 is supported on its one free end face 82 against an energy store 84 in the form of a compression spring. Guides 86, 88 for the energy store 84 are formed on the valve slide 16 and on the opposite end screw 22. On its other free end 90, the valve slide 16 adjoins a volume space 92 of variable volume, into which an inner channel 94 of the valve slide 16 opens at its one end 96, the other end 98 of which enters the first fluid guide 58 between the two control parts 34, 56, directly adjacent to the transition part 70 opens out.

A corresponding fluid channel 100 is provided in the valve housing 12 to map the fluid pressure according to at least one fixed or adjustable measuring orifice 99 on the one free end face 82 of the valve slide 16.

The graph of the Fig. 6 shows the course of the standard cross-section over the opening stroke. From a defined opening stroke, the first guide part 60 is out of contact with the housing inner wall 62, so that the load-holding function is overcome and fluid from the fluid connection point 30, which forms the fluid inlet 102, to the fluid connection point 32, which forms the fluid outlet 54, can flow. Starting from this opening stroke, the standard cross section increases disproportionately with the increasing opening stroke, until the standard cross section increases proportionally to the opening stroke from a kink-free transition. According to the invention, the control quality and the stability are essentially due to a monotonically increasing increase over the opening stroke Standard cross-section without kinks and with a very flat initial slope improved.

The invention therefore shows particularly advantageous pressure balances. The pocket-like depressions 38 no longer open out at an edge, but rather merge smoothly into the end face 104 of the first control part 34. This has the advantage that the standard cross-section does not change abruptly at an edge. Therefore, the course of the standard cross-section does not have a kink over the opening stroke (cf. Fig. 6 ). The control quality of the valve components 10 is therefore considerably higher and the stability of the control is also improved. A trailing edge 72 is provided on the second control part, at which the flow surface merges from an annular switching edge surface 64 extending in the radial plane into an outer circumferential surface 68 extending coaxially to the longitudinal axis LA of the valve slide 16. A load-holding function for the valve is implemented particularly favorably by the step-like switching edge surface 64. This prevents fluid from flowing from the fluid outlet 54 to the fluid inlet 102 against the normal flow direction. Finally, the further fluid guide 76 advantageously improves the flow around the second control part 56 and facilitates the resetting of the valve slide 16. In addition, the further fluid guide 76 advantageously reduces the sealing gap between the first guide part 60 and the housing inner wall 62.

Claims (6)

1. Pressure compensator with a valve slide (16) mounted in a valve housing (12) such that it can be displaced longitudinally, said valve slide comprising a control part (34) to actuate a fluid-conducting connection (28) between at least two fluid connection points (30, 32) received in the valve housing (12), said control part having at least one pocket-like depression (38), which is delimited at least partially by a fluid guide surface (40), which extends at least between two apexes (M1, M2, M3) of the depression (38) and which, starting from one apex (M1; M2, M3), has a quantitatively rising gradient (S1, S2, S3, S4; S11, S12, S13, S14) towards the other apex (M2, M3; M1), characterised in that, starting from a pre-definable distance (A1; A2) from the other apex (M2, M3; M1), the fluid guide surface (40) extends from its maximum gradient (S4; S14), towards said other apex (M2, M3; M1) with a quantitatively decreasing gradient (S4, S5, S6, S7; S14, S15, S16, S17).
2. Pressure compensator according to claim 1, characterised in that the fluid guide surface (40) has a constant course and the lowest gradient amount, preferably assuming a value of zero, at the respective other apex (M1, M2, M3).
3. Pressure compensator according to either claim 1 or claim 2, characterised in that the fluid guide surface (40) is designed as a curve and in that the different gradient courses between the apexes (M1, M2, M3) are achieved by passing from a concave to a convex curve shape.
4. Pressure compensator according to any one of the preceding claims, characterised in that as many pocket-like depressions (38) are arranged along the outer circumference (36) of the control part (34) of the valve slide (16) as to ensure that the fluid guide surfaces (40) between the individual apexes (M1, M2, M3) form a closed sinusoidal or cosinusoidal curve shape along said outer circumference (36).
5. Pressure compensator according to any one of the preceding claims, characterised in that, at least in some of the pocket-like depressions (38) in the region of an apex (M2), a groove-like depression (50) is connected to the pocket-like depression (38) at the bottom side.
6. Pressure compensator according to any one of the preceding claims, characterised in that the largest opening cross-section (52) of the respective pocket-like depression (38) is oriented towards the fluid connection point (32) that forms the fluid outlet (54) from the valve housing (12).

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