VALVE APPARATUS FOR INFLUENCING A FLOW OF MEDIUM

Abstract

A valve apparatus for influencing a flow of medium between a supply port (38) and a pressure port (40), having a valve device (10) which, in at least one closed position, blocks the connection between the supply port (38) and the pressure port (40) and which opens this connection in at least one opened position, in which the pressure port (40) is connected to at least one of two medium chambers (62, 80) by a respective fluid channel (64, 82), of which one (64) consists of a fluid duct (68) in the valve slider (22), is characterized in that the other fluid channel (82) has at least one further fluid duct (84) which is separate from the first fluid duct (68) and which, at least in one of the opened positions of the valve slider (22), opens at one end (92) into the medium chamber (80) and which, in every displacement position of the valve slider (22), is permanently connected at the other end (94) to the pressure port (40).

Claims

1. A valve device for influencing a media flow between a supply port (38), to which a pressure supply source (P) can be connected, and a pressure port (40), to which a hydraulic consumer (U) can be connected, having a valve device (10), which has a valve spool (22), which is guided in axial travel directions within a valve housing (18) and the opposite end faces (60, 78) of which at least partially delimit two media chambers (62, 80) within the valve housing (18) and which blocks the connection between the supply (38) and the pressure port (40) in at least one closed position and which releases that connection (36) in at least one of its open positions, in which the pressure port (4) is connected to at least one of two media chambers (62, 80) via a relevant fluid guide (68), one of which (64) is formed of a valve spool (22) located in the fluid duct (68), one end (70) of which opens into a media chamber (62) and the other end (72) of which opens into a fluid chamber (48) in the valve housing (18), which fluid chamber is separated from the pressure port (40) in the at least one closed position of the valve spool (22) and disposed between the supply port (38) and the pressure port (40) characterized in that the other fluid guide (82) has at least one further fluid duct (84), which is separated from the first fluid duct (68) and the one end (92) of which opens at least in one of the open positions of the valve spool (22) into the other media chamber (80) and the other end (94) of which is permanently connected to the pressure port (40) in every travel position of the valve spool (22).

2. The valve device according to claim 1, characterized in that the relevant further fluid duct (84) is arranged in parallel to the axial directions of travel of the valve spool (22) and the fluid guide (82) of the relevant further fluid duct (84) is subject to a deflection from this parallel direction when an assignable regulating edge (90) in the valve housing (18) is passed over transversely to the fluid guide.

3. The valve device according to claim 1, characterized in that the relevant further fluid duct (84) is arranged in parallel to the axial traversing directions of the valve spool (22) and when passing an assignable control edge (90) in the valve housing (18) transversely to the same fluid guide (82) of the relevant further fluid duct (84) is subject to a deflection from this parallel direction.

4. The valve device according to claim 1, characterized in that the duct cross-section tapers at least in the area of the assignable regulating edge (90) while forming an aperture (98) with the latter, starting from the respective further fluid duct (84), in the direction of the relevant control duct (96).

5. The valve device according to claim 1, characterized in that the relevant control duct (96), seen in cross-section, tapers conically in the direction of a free end face (78) of the valve spool (22), which end face at least partially limits the other media chamber (80), and the end (100) facing the relevant assignable fluid duct (84) of which opens into the fluid duct, forming a ledge-like fluid guiding stage (102).

6. The valve device according to claim 1, characterized in that in a development of a control edge (114) of the valve spool (22) in the area of the at least one regulating edge (90) in the valve housing (18) in a plane, the total length of the control edge is greater than the sum the individual developments, relative to the same plane, of the free openings (74) of the one fluid duct (68) located in the valve spool (22) in the area of its other end (72), which opens into the fluid chamber (48) in the valve housing (18).

7. The valve device according to claim 1, characterized in that the relevant further fluid duct (84) is formed from a radial wall spacing (89) between the valve spool (22) and the valve housing (18).

8. The valve device according to claim 1, characterized in that the radial wall spacing (89) between the valve housing (18) and valve spool (22) is formed by a uniform diameter reduction (86) in the valve spool (22), based on the diameter (88) of the free end face (78) of the valve spool (22), in the direction of the other media chamber (80), and that if required the existing control duct opens in a fluid conveying manner into the fluid ring duct formed in that way.

9. The valve device according to claim 1, characterized in that the regulating edge (90) located in the valve housing (18) encompasses the valve spool (22) in the regulating position and limits a groove-like recess (116) pointing away from the valve spool (22) protruding in its direction.

10. The valve device according to claim 1, characterized in that at one end position, in particular at a stop position of the valve spool (22) in the direction of the other media chamber (80), the relevant further fluid duct (84) has traveled over the regulating edge (90) thereby forming a 90 deflection for the fluid guide (82) and opens at the end into the relevant further fluid duct (84) at a possibly existing control duct (96).

Description

[0016] The invention is explained in more detail with reference to exemplary embodiments illustrated in the figures. In the Figures:

[0017] FIG. 1 shows a hydraulic symbol representation of a volumetric flow regulator having a valve device according to the invention;

[0018] FIG. 2 shows a longitudinal section through the valve device of FIG. 1 having a valve spool in the left stop position in the direction of the one media chamber;

[0019] FIG. 3 shows a longitudinal section through the valve device of FIG. 1 having a valve spool in the right stop position in the direction of the other media chamber;

[0020] FIG. 4 shows an enlarged view of an area surrounded by a circle X in FIG. 3; and

[0021] FIG. 5 shows an enlarged view of the area bordered by the circle X in FIG. 3 in a modified embodiment compared to the embodiment according to FIG. 4.

[0022] FIG. 1 shows in the form of a hydraulic symbol representation a pressure maintenance-type component 9 in conjunction with a metering aperture 12, which in the overall function form a volume flow regulator 14 having the valve device according to the invention having the valve device 10, the essential components of which are combined in a frame-like block representation

[0023] According to the longitudinal sectional views of FIGS. 2 and 3, a valve housing 18 has a valve bore 20, in which a longitudinally movable guided valve spool 22 is arranged. The valve bore 20 is closed at both ends 24, 26 by cap screws 28, 30, which each engage in an assignable female thread 32 of the valve bore 20. Annular sealing elements 34 are provided between the cap screws 28, 30 and the valve housing 18.

[0024] 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 (FIG. 1) in the form of a hydraulic pump 41 is connected to the supply port 38, and a hydraulic load U (FIG. 1), for example in the form of a hydraulic power cylinder (not shown), can be connected to the pressure port 40 via the connection point P of the valve device 10. The valve spool 22 has a total of two outwardly projecting control parts 42, 44, of which the first control part 42 has at least one pocket-like recess 46 in the direction of the second control part 42 and the second control part 44 is arranged at a distance from the first control part 42 by a first fluid chamber 48 as part of the possible fluid-conveying connection 36. In principle, the solution according to the invention can be implemented using only one control part, for example, the control part 42, which, however, results in disadvantages in the overall control behavior of the piston-like valve spool 22. In the unactuated state of the valve spool 22, i.e. at zero stroke, in which the valve spool 22 is in the left end position in the image plane (FIG. 2), the second control part 44 is in contact with an inner housing wall 52 of the valve housing 18 by means of a cylindrical guide part 50. A conical transition part 54 at the control part 44 forms a flow guide for the fluid and causes a ramp-like deflection of the fluid flow from the first fluid chamber 48 in the direction of the pressure port 40. The transition part 54 also contributes to the flow force compensation at the valve spool 22.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] At its other end face 78, the valve spool 22 adjoins another media chamber 80 of variable volume, which, viewed in the direction of FIGS. 2 and 3, for a predetermined opening displacement of the valve spool 22 towards the right and thus in the direction of the other media chamber 80, is connected to the pressure port 40 in a fluid-conveying manner via another further fluid guide 82, such that the one media chamber 62 can be connected to the other media chamber 80 via the one fluid duct 68 and the other fluid duct. FIG. 3 shows the pertinent fluid-conveying connection between the pressure port 40 and the media chamber 80 Furthermore, one free end of the end face 78 of the valve spool 22 rests against a compression spring 112, the other free end of which is in contact with the end screw 30 thereby passing through the other media chamber 80. Further, the compression spring 112 having a predefined prestress is in abutment with the slider 22 even in the zero position of the valve spool 22 (FIG. 2).

[0029] As further shown in FIGS. 4 and 5, the other fluid guide 82 is formed by the further fluid duct 84, which extends in the form of a diameter reduction 86 of the valve spool 22, in relation to a diameter 88 of the free other end face 78 of the valve spool 22 and limited by the further guide part 56 of the valve spool 22, in parallel to the axial travel directions thereof. In this way, the further fluid duct 84 may be formed as at least one groove-shaped diameter reduction 86 in the valve spool 22 or preferably from a radial wall spacing 89 between valve spool 22 and valve housing 18 along the entire outer circumference of the valve spool 22 in this area. The radial wall spacing 89 between the valve housing 18 and valve spool 22 is formed by the uniform diameter reduction 86, based on the relevant diameter 88 of the free other end face 78 of the valve spool 22, in the valve spool 22 in the direction of the pressure port 40 as this area.

[0030] 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 FIG. 1 by the representation of a throttle or aperture 99. The total length of the development of the control edge 114 in a fictitious plane extending horizontally (not shown) is greater than the sum of the individual developments, in relation to that same horizontal plane, of the free openings 74 of the first fluid duct 68 located in the valve spool 22 in the area of its other end 72, which opens into the first fluid chamber 48 in the valve housing 18 via these openings 74.

[0031] As shown in FIG. 5 in a modified embodiment of the solution according to FIG. 4, the other end 92 of the further fluid duct 84, shown in FIG. 4 and described above, facing the other media chamber 80 adjoins at least one control duct 96, the duct cross-section of which is reduced in comparison to the further fluid duct 84. The relevant control duct 96, viewed in cross-section, tapers in the direction of the other free end face 78 of the valve spool 22 and its end 100 facing the further fluid duct 84 opens into the further fluid duct 84 to form a shoulder-like fluid guide stage 102. Viewed in the direction of FIG. 5, the conically reduced cross-section of the right end of the control duct 86 forms a further control edge 115 at the free end of the valve spool 22, which forms a further throttle or aperture device for the fluid with the control edge 90 of the housing 18, as soon as the further control edge 115 passes over the free cross-section at the stationary regulating edge 90, which happens if, during opening valve positions, the valve spool 22 travels from its zero position shown in FIG. 2 to its regulating positions in the direction of the end or stop position according to FIG. 3 towards the right.

[0032] 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.

[0033] As shown in FIG. 1, the hydraulic consumer U is connected to the connection port P of the valve device 10 at the pressure port 40 via a fluid-conveying line 104. A regulating device, in particular formed in the manner of the metering aperture 12, is provided in the fluid-conveying line 104. For mapping the fluid pressure between the consumer U and the metering aperture 12 to the other end face 78 of the valve spool 22, a corresponding control line 106 in the form of an LS signal line 108 is provided, which is connected to the valve housing 18 and which opens into the other media chamber 80. The LS signal line 108 is in turn connected to the hydraulic pump 41 in the form of a variable displacement pump 16. The pivoting angle of the hydraulic pump 41, which also specifies the pressure at the supply port 38, is regulated as a function of the system pressure in the LS signal line 108. The hydraulic load message system formed in that way can be used to quickly adapt the pressure at the supply terminal 38 provided by the hydraulic pump 41 to the requirements of the hydraulic consumer U. Furthermore, provision is made that fluid can flow into a tank connection or other return port R at substantially ambient pressure via the LS signal line 108, from the other media chamber 80 via an adjustable throttle or aperture 110. The LS signal line 108 also has a comparable throttle or aperture 110.

[0034] 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.

[0035] 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.

[0036] Below, the operation of the valve device, as far as necessary for understanding the invention, is explained in more detail:

[0037] In the unactuated state of the valve spool 22, i.e. at zero stroke (FIG. 2), wherein the valve spool 22 is positioned in stop position in the direction of the one media chamber 62, the second control part 44 is in contact with the inner housing wall 52 of the valve housing 18 in the area between supply port 38 and pressure port 40 by means of the cylindrical guide part 50, such that the valve spool 22 is arranged in one of its closed positions SS, in which it blocks the fluid-conveying connection 36 between the supply port 38 and the pressure port 40. In this position SS, the further fluid duct 84 and optionally the control duct 96 is covered by the inner housing wall 52 in a sealing manner and the end portion of the further guide part 56 is in sliding contact with the assignable inner housing wall 52 facing other media chamber 80.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.