Patent Application
20190120260
The invention relates to a valve device for influencing a media flow between a supply port to which a pressure supply source can be connected, and a pressure port to which a hydraulic consumer can be connected, having a valve device, which has a valve spool, which is guided in axial travel directions within a valve housing and the opposite end faces of which at least partially delimit two media chambers within the valve housing and which blocks the connection between the supply and the pressure port in at least one closed position and which opens that connection in at least one of its open positions, in which the pressure port is connected to at least one of two media chambers via a relevant fluid guide, one of which is formed of a valve spool located in the fluid duct, one end of which opens into a media chamber and the other end of which opens into a fluid chamber in the valve housing, which chamber is separated from the pressure port in the at least one closed position of the valve spool and disposed between the supply port and pressure port.
The solution according to
In a preferred embodiment of the known valve device, the valve housing opens into a control line, which is preferably part of an LS signal line or signal chain. To actuate this control line, the control device has a single fluid duct within the valve spool serving as a control duct, which on a control side of the valve spool opens into a media chamber within the valve housing and which fluid duct connects this media chamber to a further media chamber, to which the control line and the LS signal line are connected, within the valve housing in a fluid conveying manner from a predetermined displacement position of the valve spool, which position preferably corresponds to a stop or end position.
In the known solution, the only control or fluid duct is implemented by a system of longitudinal and transverse bores in the valve spool, the dimensioning of which has to be as accurate as possible to perform the actuation, resulting in high production cost. It has also been shown in practice that, due to the relatively narrowly dimensioned free duct cross-sections of the control duct mentioned, problems can occur in the immediate transmission of the hydraulic pressure present at the pressure port to the actual regulating side of the valve, which results in pressure losses within the fluid guide and consequently to instabilities in the fluid control, which is detrimental to the desired constant pressure reduction on the pressure supply side of the valve. To increase the volume flow using a pressure divider circuit p′ downstream of LS, the pressure p′ cannot be tapped correctly due to the position of the bore in front of the non-return edge, but is increased by the switching edge as a function of the volume flow Q and the [size of the] opening.
Based on this prior art, the invention therefore addresses the problem of further improving this known solution in that the operating behavior in regard to regulation is improved in a cost-effective implementation, while maintaining the advantages of the known solution, namely to achieve a limitation of the valve spool regulated pressure at the pressure or service port of the valve.
A valve device having the features of claim 1 in its entirety solves this problem.
Because, according to the characterizing part of claim 1, the other fluid guide has at least one further fluid duct, which is separated from the first fluid duct and one end of which opens in at least one of the open positions of the valve spool into the other media chamber and the other end of which in each travel position of the valve spool is connected permanently to the pressure port, the known one-duct solution described above is replaced by a two-duct solution having shortened fluid paths per duct, thus preventing high pressure losses at the actuated regulating side of the valve, which might result in instabilities in fluid control. The further fluid duct being permanently connected to the pressure port of the valve to be regulated, such that the control processes take place immediately and without pressure losses due to the otherwise additionally necessary duct guides also contributes to this purpose. The desired regulating processes using the valve device also lead to an overall improved energy balance and the instabilities due to excessive pressure losses mentioned above are prevented with certainty in this way. In spite of the two-duct design, the overall manufacturing costs are reduced, as due to the simpler duct design and the, to that extent also easier-to-control, regulation and actuation geometries the manufacturing cost is reduced accordingly.
In a preferred embodiment of the valve device according to the invention, the further fluid duct is arranged in parallel to the axial travel directions of the valve spool, such that when passing an assignable regulating edge transversely to the latter by means of the valve spool, the fluid guide of the further fluid duct is deflected from this parallel direction, preferably by 90°. In this way, the two-duct solution having the further fluid duct, which is permanently connected to the pressure port in every travel position of the displacement piston, can be used to achieve an improved regulation quality or control quality compared to the known single-duct solution, in which the fluid guide of the duct emerges perpendicular in planes, parallel to the addressed regulating edge, during the control process.
In a further preferred embodiment of the valve device according to the invention, at least one control duct adjoins one end of the relevant further fluid duct, which points in the direction of the other media chamber, which has a changed, in particular reduced, duct cross-section with respect to the further fluid duct. Preferably, provision is made that the duct cross-section tapers at least in the area of the assignable regulating edge while forming an aperture with the latter, starting from the relevant further fluid duct, in the direction of the relevant control duct. In this way, the relevant further fluid duct in functional connection with the relevant further control duct achieves a type of pressure divider circuit in the regulation position of the valve, which can be used to noticeably increase the required control pressure on the pressure delivery side of the valve. This is without parallel in the prior art.
In this case, particularly preferably provision is made that the cross-section of the relevant control duct tapers conically in the direction of a free end face of the valve spool, which end face at least partially limits the other media chamber, and the end facing the relevant assignable fluid duct of which opens into the fluid duct forming a ledge-like fluid guiding stage. In the pertinent arrangement, the control duct adjoining the relevant fluid duct provides for a fluid flow path, which provides for the required initial regulation processes at the valve spool in a largely continuous manner without obstruction, upon a small alteration of the fluid direction with respect to the parallel alignment at the regulating edge transversely to the same.
To maintain a particularly high regulation quality, it has proven to be advantageous to design the valve such that in a fictitious development of a control edge of the valve spool in the area of at least one regulating edge in the valve housing in a plane, the total length of the control edge is greater than the sum of the individual developments, relative to the same plane, of the free openings of one of the valve ducts located in the fluid passage in the area of its other end, which opens into the fluid chamber in the valve housing.
A particularly high production quality can be achieved at low manufacturing costs if the relevant further fluid duct is formed from a radial wall spacing between the valve spool and the valve housing. A radial wall spacing between the valve housing and valve spool formed by a uniform diameter reduction in the valve spool, based on the diameter of the free end face of the valve spool, in the direction of the other media chamber, wherein the possibly existing control duct opens in a fluid conveying manner into the fluid ring duct formed in that way, is particularly preferred for the purpose of a simplified production. If the further fluid duct does not extend over the entire diameter in the outer wall of the valve spool, the selection of this free diameter can be used to fine-tune the regulation process in the fluid guide.
A defined regulating edge geometry can be achieved if provision is preferably made in the valve device according to the invention that the control edge located in the valve housing is delimited by a groove-like recess pointing away from the valve spool protruding in its direction.
In the end position of the valve spool, in particular at a designated stop position in the direction of the other media chamber, the relevant further fluid duct has passed over the regulating edge forming a 90° deflection for the fluid guide for the regulation process, wherein the possibly existing control duct opens unilaterally into the relevant further fluid duct at this level of the control edge.
Preferably, the valve device is designed as a kind of pressure maintenance-type component.
The invention is explained in more detail with reference to exemplary embodiments illustrated in the figures. In the Figures:
According to the longitudinal sectional views of
The valve spool 22 is provided for controlling a fluid-conveying connection 36 between at least two fluid connection points 38, 40 mounted in the valve housing 18, a supply port 38 and a pressure port 40. A pressure supply source P (
The valve spool 22 is guided through the inner wall 52 of the latter by means of a further guide part 56 in the area of the pressure port 40 in the valve housing 18. A rod part 57 is arranged between the first control part 42 and the second control part 44, keeping them at a distance. A second fluid guide 58 between the second control part 44 and the further guide part 56 improves the fluid circulation of the valve spool 22 in the area of the second control part 44, thereby reducing the pressure losses inside the pressure maintenance-type component 9. Furthermore, the sealing behavior of the second control part 44 with respect to the inner housing wall 52 is improved by the second fluid chamber 58, as the sealing gap between the valve spool 22 and the inner housing wall 52 can be reduced by the introduction of the second fluid chamber 58 into the valve spool 22. The two fluid chambers 48, 58, which form axial distances between the first control part 42 and the second control part 44 or between the second control part 44 and the further guide part 56, are formed by groove-like diameter reductions 59 in the valve spool 22. Such diameter reductions 59 are in technical terms also referred to as cut-ins in the valve spool 22.
The valve spool 22 adjoins a media chamber 62 of variable volume, which is connected to the first fluid chamber 48 in a fluid conveying manner via a fluid guide 64 on its one end face 60, to the left in the image plane. The fluid guide 64 is formed by a fluid duct 68 located in the center of the valve spool 22, the one longitudinal end 70 of which opens into the one media chamber 62 and other transverse end 72 of which opens into the first fluid chamber 48 between the two control parts 42, 44 of the valve spool 22 in the valve housing 18 via an opening 74. The edges of the first fluid chamber 48 are bordered by the two control parts 42, 44 of the valve spool 22 and the valve housing 18.
The pressure between the supply port 38 and the pressure port 40, which is regulated by the valve spool 22 if the valve is open, is transmitted into the one media chamber 62 via the fluid duct 68. The fluid pressure existing in the one media chamber 62 then pressurizes the valve spool 22 further in the direction of one of its open positions for the purpose of bringing about a fluid connection with an enlarged passage between the pressure supply port 38 and the pressure port 40. The fluid passage 68 in the valve spool 22 has a restriction 76 in the area of its deflection from the longitudinal to the transverse duct guide. A further restriction 77 is formed by a graduated expansion of the diameter of the fluid duct 68 at the end, starting from the other end 72 of the fluid duct 68 in the direction of the one end 70 of the fluid duct 68. These restrictions 76, 77 transmit pressure fluctuations at the supply port 38 in a delayed and attenuated manner to the one media chamber 62 if the valve spool 22 is in one of its open, fluid-passing positions.
At its other end face 78, the valve spool 22 adjoins another media chamber 80 of variable volume, which, viewed in the direction of
As further shown in
The further, second fluid duct 84 is spatially separated from the one, first fluid duct 68 in terms of a two-duct solution and as regards the fluid management concept by two spatially separate fluid guides 82, 64 and permanently connected to the pressure port 40 in a fluid conveying manner by the one free end 94 of the second fluid duct that faces away from the media chamber 80 in every travel position of the valve spool 22 in a manner essential to the invention. In the direction of the other media chamber 80, the diameter reduction 86 of the valve spool 22, spaced from the other end face 78 of the valve spool 22, formed in or on the further guide part 56 terminates at one end 92 and, in the area of an assignable regulating edge 90 in the valve housing 18, abruptly transitions into the full diameter 88 of the end portion of the further guide part 56 of the valve spool 22 adjoining the other end face 78 of the valve spool 22, whereby a control edge 114 is formed at the location of the offset in the valve spool 22. The regulating edge 90, fixedly arranged in this respect, then forms the cross-section of the aperture or control between the pressure or consumer port 40 and the media chamber 80 to be regulated by the movable control edge 114, which is symbolically represented in
As shown in
The relevant control duct 96 opens into the fluid ring duct formed by the radial wall spacing in a permanently fluid conveying manner if the diameter reduction 86 is formed as a radial wall spacing 5 between valve spool 22 and valve housing 18. Instead of a single or multiple control ducts 96, only one control duct space having a conical cross-section in the valve spool 22 can be formed by a circumferential diameter reduction.
As shown in
A fluid pressure existing in the other media chamber 80 pressurizes the other end face 78 of the valve spool 22 to the left in the direction of the closed position SS, in which the valve spool 22 completely disconnects the pressure port 40 from the supply port 38 at zero stroke. In addition, the other end face 78 of the valve spool 22 is pressurized by the energy store in the form of the compression spring 112.
The pressure regulated by the valve spool 22 between the supply port 38 and the pressure port 40 can be limited by means of the one fluid duct 68, the further fluid duct 84 and optionally by the control duct 96 adjacent to the further fluid duct 84, starting from a predetermined displacement of the valve spool 22 in the direction of the other media chamber 80, namely by discharging excess fluid via the control line 106 into the LS signal line 108 from the other media chamber 80 based on the interposition of the throttle or aperture 99.
Below, the operation of the valve device, as far as necessary for understanding the invention, is explained in more detail:
In the unactuated state of the valve spool 22, i.e. at zero stroke (
A fluid pressure present at the supply port 38 is transmitted into the one media chamber 62 via the one fluid duct 68. There it acts on the adjacent end face 60 of the valve spool 22. On the opposite other end face 78, the valve spool 22 is pressurized by the load pressure via the LS signal line 108 and the control line 106 and the compression spring 112. If the fluid pressure at the supply port 38 exceeds the counter pressure by the load pressure and the compression spring 112, the valve spool 22 moves from the closed position SS in the direction of the other media chamber 80, such that the valve attains one of its open positions. As a result of this increasing displacement of the valve spool 22, the second control part 44 is brought out of engagement with the inner housing wall 52 such that the fluid-conveying connection 36 between the supply port 38 and the pressure port 40 is also progressively opened.
From a predetermined displacement of the valve spool 22, the further fluid-conveying connection 48 is interrupted by closing the first control part 42 at a further closing edge 51 of the housing 18 and simultaneously the fluid-conveying connection between the media chambers 62, 80 is established because, if no control duct 96 is provided, the other end 94 of the further fluid duct 84 or, if a control duct 96 is provided, the other media chamber 80 facing the end of this control duct 96, has passed over the regulating edge 90 in the valve housing 18, which is present in the inner housing wall 52 of the valve housing 18, thereby forming a corresponding deflection for the other fluid guide 82, which limits a groove-like recess 116 facing away from the valve spool 22 but protruding in its direction. This further fluid-conveying connection 118 between the media chambers 62, 80 results in pressure equalization between these media chambers 62, 80.
Under the action of the compression spring 112, the valve spool 22 is again moved to the left in the direction of its closed position SS, as long as the pressure equalization in the chambers 62, 80 is present. Because the fluid from the other media chamber 80 can only flow to a very limited extent, i.e. throttled, in the direction of the LS signal line 108 and optionally in the direction of the return port R or tank port via the control line 106, effect is amplified. If the valve spool 22 has moved sufficiently far in the direction of the closed position SS, the inner housing wall 52 of the valve housing 18 overlaps the further fluid duct 84, and possibly the control duct 96, in an at least partially sealing manner and subsequently a contact of the end area of the further guide part 56 facing the other media chamber 80 occurs, whereby the fluid-conveying connection between the media chambers 62, 80 is, upon increasing displacement of the valve spool 22 to the left, initially throttled and subsequently completely disconnected. Due to this mode of operation described above, an equilibrium position normally sets in which limits the pressure at the pressure port 40 advantageously to a pre-definable maximum value. Consequently, the hydraulic consumer U can no longer be overloaded. Advantageously, the fluid pressure at the pressure port 40 has a constant pressure difference to the supply port 38 until the permissible maximum pressure is reached. The aperture or regulating cross-sections 90, 114 and, possibly, 90, 115 ensure that the pressure P′ upstream of the metering aperture 12 can be set in a defined manner, regardless of the current fluid demand at the consumer U.
As a result, a valve device is shown, which prevents the pressure fluctuations at the supply port 38 from passing through the pressure maintenance-type component 9 in an undamped manner and thus effectively prevents any overload of the hydraulic load U and also advantageously improves the control performance while simultaneously providing for a cost-effective implementation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 007 754.9 | Jun 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/000700 | 6/16/2017 | WO | 00 |
