Exit valve

Abstract

Hydrostatic directional control valve (1) with a valve housing (6) in which a valve bore (4) is formed in which a valve spool (2) is guided, with which a fluid connection to at least two consumer ports (A, B) can be controlled, characterized in that the valve spool (2) is designed as a sleeve, wherein a fluidic separation between the two consumer ports (A, B) is effected by a separating piece (8) arranged within the valve spool (2) and supported in a fixed position on the valve housing (6).

Description

[0001] The invention relates to a hydrostatic directional control valve according to the preamble of claim 1.

[0002] Such a directional control valve is disclosed in EP 0 894 299 B1. This valve has a valve body in which a pressure port, a tank port, and a consumer port are formed. A fluid connection between these ports is controllable via a valve spool. This spool is slidably guided in a valve bore of the valve body. The valve spool has a sleeve section, each end of which is closed by a sealing element. Four elongated holes, arranged one behind the other in the circumferential direction, are provided in the sleeve section; these serve as control edges.

[0003] A disadvantage of this solution is that the valve spool is subjected to comparatively high pressure and flow forces. This results in high actuation forces required by the actuator and a comparatively low adjustment dynamic of the valve spool. Furthermore, this 3-way pressure valve with a single consumer connection has a limited range of applications.

[0004] DE 10 2006 040 052 A1 discloses a multi-way valve with a centering device.

[0005] In contrast, the invention is based on the objective of creating a directional control valve that eliminates the aforementioned disadvantages.

[0006] This problem is solved with a hydrostatic directional control valve according to the features of claim 1.

[0007] Other advantageous embodiments of the invention are the subject of further dependent claims.

[0008] According to the invention, a hydrostatic directional control valve with a valve housing is provided. A valve bore is formed in the housing, in which a valve spool is slidably guided. A fluid connection to at least two consumer ports, which are fluidically separated within the valve, can be controlled via the valve spool. According to the invention, the valve spool is designed as a sleeve or sleeve spool. Advantageously, a separating element is provided within the valve spool for fluidically separating the consumer ports. This separating element can be fixedly supported on the valve housing.

[0009] This solution has the advantage that, due to the fixed support of the separating piece, no pressure and / or flow forces are transmitted from the separating piece to the valve spool. Furthermore, the valve spool has only a few (annular) surfaces where pressure and / or flow forces can act. Thus, due to the separating piece and the sleeve-shaped design of the valve spool, extremely low pressure and / or flow forces act upon it, yet it can still be used to control multiple consumer connections.

[0010] In conventional directional control valves with continuously adjustable valve spools, the pressure and / or flow forces acting on the spool can increase significantly with increasing stroke. Due to the design of the directional control valve according to the invention, low pressure and / or flow forces act on the valve spool, which is why a large stroke for the valve spool is possible with comparatively low actuation forces. The larger stroke, in turn, leads to a higher fluid flow rate through the directional control valve.

[0011] If a conventional actuator is used to operate the valve spool, it will require less power. Due to the lower pressure and flow forces, it is conceivable to use a comparatively small actuator, thus saving installation space and costs. However, if a conventional actuator is used, it will have a higher power limit.

[0012] Due to its sleeve-like design, the valve slide has a comparatively low mass. Furthermore, such a valve slide exhibits relatively high natural frequencies. For this reason, it can be operated with high dynamics without reaching its natural frequencies.

[0013] It is conceivable that the valve slide is guided with slight play between the valve bore and the separating piece.

[0014] In a further embodiment of the invention, a housing-mounted retaining element can be provided to fix the separating piece, which engages in a recess of the separating piece.

[0015] Advantageously, the retaining element extends from the valve housing through an opening formed in the valve spool and engages in the recess of the separating piece. The opening interacts with the retaining element in such a way that it acts as an anti-rotation device for the valve spool. Additionally, it is designed to allow the valve spool to slide longitudinally relative to the retaining element.

[0016] The recess in the separating piece can extend diagonally or radially through it completely. The retaining element, in turn, can then completely penetrate the recess via two openings, particularly those diametrically positioned in the valve slide, and be fixed or supported at its two end sections on the valve housing.

[0017] The opening, or the respective opening, is advantageously designed as a simple elongated slot extending longitudinally along the valve spool. The retaining element can be pin-shaped. The width of the elongated slot is chosen such that the retaining element can slide relative to the slot, and the valve spool is also essentially secured against rotation. The length of the elongated slot is such that the valve spool can be displaced by the required stroke.

[0018] The retaining element is, for example, a bolt or a screw. It can be arranged radially to the valve spool or pass diagonally through it. Receptacles for the retaining element in the valve housing can be designed radially to the valve bore.

[0019] Preferably, the separating piece is arranged approximately in the middle of the valve slide when viewed longitudinally.

[0020] To prevent fluid from flowing through the opening or both openings, the separating piece is designed to cover the opening or both openings.

[0021] The separating piece can have an approximately circular cross-section in its center (viewed longitudinally) and a web extending from its center (viewed longitudinally) on each side. This reduces the cross-section of the separating piece off-center in such a way that the openings are covered and pressurized fluid can flow past the separating piece from a connection when the valve spool is in its switching positions.

[0022] The directional control valve can be used for a variety of applications where at least two consumer ports, or other ports, need to be fluidically isolated from each other. For example, it can be used as a 4 / 3-way valve to control the fluidic connection between a pressure port, a tank port, and the two consumer ports. Alternatively, it can be configured as a 5 / 3-way, 5 / 2-way, 4 / 2-way, or 3 / 2-way valve.

[0023] The pressure connection can be designed as an annular chamber in the center of the valve bore. Adjacent to the pressure connection, a first and second consumer connection can also be provided in the valve bore, likewise as annular chambers. Adjacent to these consumer connections, a corresponding tank connection can be provided within the valve bore. Thus, each consumer connection is located between the pressure connection and its associated tank connection.

[0024] It is conceivable that, starting from a home position and moving towards the first switching positions, a fluid connection between the pressure port and the first consumer port, and between the tank port and the second consumer port, can be controlled via the valve spool. Starting from a home position and moving towards the second switching positions, a fluid connection between the pressure port and the second consumer port, and between the tank port and the first consumer port, can be controlled. In the home position, the ports can be separated from each other.

[0025] For fluidic connection of the consumer ports, windows can be incorporated into the valve spool. This results in a skeletal structure of the valve spool, making its weight comparatively low. This further increases the natural frequencies of the valve spool and enhances its dynamics.

[0026] The windows can be used for the fluidic connection of a respective consumer connection to the tank connection or the pressure connection, thus allowing the windows to represent control edges.

[0027] In a further embodiment of the invention, at least one window is provided on each side of the separating piece in the valve slide. The at least one window on one side can serve to control the fluid connection to the first consumer port, and the at least one window on the other side can serve to control the fluid connection to the second consumer port.

[0028] Advantageously, a plurality of windows are provided for each fluid connection.

[0029] Advantageously, the valve slide can be designed to be largely open in the area of ​​at least one window in the circumferential direction. This means that the window, or multiple windows, extend extensively around the valve slide. The window(s) then form a so-called 360° control edge for each consumer connection. Due to the open design of the valve slide, flow resistance is significantly reduced. It would also be conceivable to provide at least a 180° control edge.

[0030] If a plurality of windows are provided for the respective fluid connection to a respective consumer connection via the valve slide, this plurality of windows can be separated or delimited from each other in the circumferential direction by webs extending approximately axially.

[0031] Advantageously, four windows are provided for each fluid connection to a respective consumer port, each arranged in series at approximately 90° intervals around the valve spool. In the direction of rotation, they are separated by the approximately axially extending web.

[0032] In a further embodiment, the separating element in the valve slide can separate two cavities from each other, with the windows serving for the fluid connection of the respective consumer port to a respective cavity. At least one control window can be provided to control a fluid connection between a pressure port, particularly a common one, and the respective cavity.

[0033] To control a fluidic connection between the respective cavity and the respective tank connection, at least one further control window can be provided.

[0034] For fine control, a notch can be added to at least one control window, to several control windows, or to all control windows.

[0035] Preferably, a pin – extending in the axial direction in particular – is fixed at the end of the valve slide, extending away from the valve slide and connectable to an actuator for actuating the valve slide.

[0036] To secure the pin, at least one ridge can be provided at the end of the valve slide. Advantageously, this ridge extends from an inner surface of the valve slide, particularly radially inwards. The pin can be connected to the ridge, for example, by press-fitting or via a thread. For this purpose, it is advantageous if a receiving sleeve for holding the pin is fixed to the ridge. This sleeve extends, in particular, approximately coaxially to the valve slide, allowing the pin to also extend approximately coaxially to the valve slide.

[0037] The bridge can be fixed on both sides of the valve slide and extend approximately diagonally inside the valve slide.

[0038] In a further embodiment, it is conceivable to provide two webs arranged in an approximately cross shape. The receiving sleeve can then be formed in the intersection area of ​​the webs.

[0039] Preferably, a pin is provided at each of the two end sections of the valve slide, which can be connected to the valve slide in accordance with the above-described embodiments.

[0040] If one or two pins are provided, at least one pin can interact with an actuator to operate the valve slide. For example, one pin is coupled to an actuator in the form of a double-stroke solenoid, or both pins are coupled to an actuator in the form of a single-stroke solenoid.

[0041] If only one pin is coupled to an actuator, then an end face of the other pin pointing away from the valve slide can be relieved towards a tank.

[0042] An end face of the pin or the end faces of a respective pin preferably correspond to a respective, in particular annular, end face of the valve slide, whereby the area of ​​the webs is disregarded.

[0043] It is conceivable that the valve spool incorporates an additional separating element to isolate one end face of the spool from the pressure and consumer connections. Naturally, a further separating element can be provided for each end face. The end face can then be discharged to a tank.

[0044] To further reduce flow resistance, the valve housing can be flow-optimized.

[0045] The windows and control windows are manufactured by milling or wire EDM into the valve slide, for example. A tube or sleeve can serve as the semi-finished product.

[0046] Preferred embodiments of the invention are explained in more detail below with reference to the drawings. These show: Fig. 1 in a perspective view a section of a directional control valve according to the invention in a first embodiment, Fig. 2a in a longitudinal section the directional control valve according to the first embodiment, Fig. 2b in a cross-section the directional control valve according to the first embodiment, Fig. 3 in a perspective view a section of the directional control valve according to the invention in a second embodiment, Fig. 4 in a longitudinal section the directional control valve according to the second embodiment and Fig. 5 in a perspective view, a separating piece.

[0047] According to Fig. In the invention, a directional control valve 1 has a valve spool 2 designed as a sleeve. This spool is guided slidably in a valve bore 4 of a valve housing 6. A separating piece 8 is arranged inside the valve spool 2, which fluidically separates a first consumer port A from a second consumer port B. The separating piece 8 is fixed to the valve housing 6 by a retaining element in the form of a bolt 10.

[0048] According to Fig. 2a The bolt 10 passes through the valve slide 2 via a first and second opening in the form of an elongated hole 12 and 14, respectively. Each elongated hole 12, 14 extends approximately in the longitudinal direction of the valve slide 2. The circumferential width of each elongated hole 12 and 14 is slightly larger than the diameter of the bolt 10 in the region of the elongated holes 12 and 14, thus allowing the valve slide 2 to slide relatively freely along the bolt 10. Furthermore, the width of each elongated hole 12 and 14 is selected such that the valve slide 2 is essentially secured against rotation by the bolt 10. A stepped blind hole 16 is provided in the valve housing 6 for the bolt 10, which passes completely diagonally through the valve bore 4. The bolt 10 has a radial collar 18 at its end, which allows the insertion depth into the blind hole bore 16 to be limited.Alternatively or additionally, the immersion depth can be limited by the bottom of the blind hole 16. The separating piece 8 has a recess in the form of a through-hole 20 to accommodate the bolt 10. The separating piece 8 is designed such that it substantially closes the elongated holes 12 and 14 in any position of the valve slide 2.

[0049] For the fluid supply of the first consumer connection A, according to Fig. First windows 22 are provided in the valve slide 2, spaced longitudinally from the elongated holes 12, 14. Second windows 24 are provided in the valve slide 2 to supply fluid to the second consumer connection B, also spaced longitudinally from the elongated holes 12, 14. In the longitudinal direction, the first windows 22 are located on one side of the separating piece 8 and the windows 24 on the other side. Four windows 22 are provided as first windows 22, each with the same axial length and approximately rectangular in plan view with rounded corners. A web 26 is provided between each window 22. The second windows 24 are designed accordingly. They also consist of four second windows 24, each separated from the other circumferentially by a web 28.

[0050] According to Fig. 2a The valve bore 4 is radially enlarged in the center by an annular chamber, which forms a pressure port P. The consumer ports A and B are also designed as annular chambers in the valve bore 4. They are each arranged adjacent to the pressure port P, so that the pressure port P is located between them. Starting from the pressure port P, a tank port T is provided downstream of each consumer port A or B, which is also designed as an annular chamber in the valve bore 4.

[0051] The first transverse edges 30 of the first windows 22 serve as control edges to control a pressure medium connection between the pressure port P and the first consumer port A when the valve spool 2 moves from its position in Fig. The valve spool 2 is moved from its initial position in the direction of the first switching positions. The second transverse edges 32 of the second window 24 serve to control a pressure medium connection between the second consumer port B and the tank port T when the valve spool 2 is moved from its initial position in the direction of the first switching positions. If the valve spool 2 is moved in the opposite direction from its initial position in the direction of the second switching positions, the third transverse edges 34 serve to control a pressure medium connection between the pressure port P and the second consumer port B. In these switching positions, a pressure medium connection between the first consumer port A and the tank port T is then controlled via the fourth transverse edges 36 of the first window 22.

[0052] To actuate the valve slide 2, its end section is connected to a pin 38, which can be coupled to an actuator. To fix the pin 38, the valve slide 2 has, according to Fig. 1 Two cross-shaped webs 40 and 42, between which a receiving sleeve 44 is formed centrally. The pin 38 is firmly inserted into this sleeve. The pin 38 also passes through a first housing cover 46 which closes the valve housing 6. On the housing cover side, the valve slide 2 is further secured via its end face 48, see Fig. 2a, subjected to a spring force of a valve spring 50.

[0053] A pin 52 is also fixed at the further end section of the valve slide 2. For this purpose, cross-shaped webs with a receiving sleeve are again provided. The pin 52 extends approximately coaxially with the valve slide 2, corresponding to the pin 38, and projects from it. The pin 52 projects into a chamber 56 via a bore formed in a second housing cover 54. This chamber is connected to a tank via a channel 58. An end face 60 of the pin 52 is thus pressure-relieved from the tank. The pins 38 and 52 have essentially the same diameter. The end face 60 of the pin 52 and an end face 62 of the pin 38 each correspond approximately to the end face 48, see [reference]. Fig. 1, where only the ring-shaped surface section of the end face 48 is taken into account.

[0054] The separating element 8 separates a first cavity 64 from a second cavity 66 in the valve slide 2. The end face 48 of the valve slide 2, in turn, defines a chamber 68, and another end face 70 of the valve slide 2 defines a chamber 72. Since the end faces 48 and 70 of the valve slide 2, which are of equal size, are open, the chambers 68 and 72 are fluidically connected to the cavities 64 and 66, respectively. If the valve slide 2 is now removed from its position in Fig. When the valve spool 2 is moved in the direction of switching positions as shown in Figure 2a, displaced pressure medium can flow from chambers 68 and 72 into cavities 64 and 66, respectively, and vice versa. A fluidic connection between chambers 68 and 72 for pressure medium equalization is therefore unnecessary, thus improving the dynamics of the valve spool 2 and reducing the required device complexity.

[0055] According to Fig. 2b the cross-shaped structure of the bridges 40 and 42 is recognizable.

[0056] According to Fig. In the first three positions, the first windows 22 and 24 are shorter in the longitudinal direction. For this purpose, additional first, second, third, and fourth control windows 74, 76, 78, and 80 are provided. The first control windows 74 allow for the control of a pressure medium connection between the pressure port P and the cavity 64 of the valve spool 2 in the first switching positions. Pressure medium can then flow from the pressure port P to the cavity 64 via the first control windows 74 and further from the cavity 64 via the first windows 22 to the first consumer port A. In the first switching positions, the fourth control windows 80 then control a pressure medium connection between the cavity 66 and the tank port T. Pressure medium can then flow from the second consumer port B into the cavity 66 via the second windows 24 and from the cavity 66 via the fourth control windows 80 to the tank port T.In the second switching positions, a pressure medium connection between the pressure port P and the cavity 66 is controlled via the second control windows 76 and a pressure medium connection between the cavity 6 and the tank port T is controlled via the third control windows 78.

[0057] According to Fig. Figure 3 provides four first control windows 74, four second control windows 76, four third control windows 78, and four fourth control windows 80. These are each significantly shorter in the circumferential direction than windows 22 and 24, respectively. Each control window 74 to 80 has a fine control notch 82, of which, for simplicity, only one is to be understood as having a reference numeral. Each fine control notch 82 is located in a respective transverse edge 84 of each control window 74 to 80.

[0058] Alternatively, it is conceivable to use chambers 68 and 72 according to Fig. 2a to be fluidically separated from the respective consumer connection A or B by providing two further separating pieces that are fixed to the housing.

[0059] The separating piece 8 has according to Fig. 5 a cylindrical main section 86, which is penetrated by the through-bore 20. Its length in the longitudinal direction of the valve slide 2, see for example Fig. 1 or Fig. 3, is shorter than the length of the elongated holes 12, 14. To ensure that these are closed by the separating piece 8, projections in the form of webs 92 and 94 are provided on the end faces 88 and 90, respectively. These extend approximately parallel to the through-bore 20. The width of the separating piece 8, viewed longitudinally, corresponds approximately to the width of the annular chamber of the pressure connection P (see Fig. 2a), wherein the separating piece 8 is enclosed by the annular chamber. If the valve slide 2 is in its switching positions, see for example Fig.2a, pressure medium can flow from the pressure port P through the windows 22 or 24 past the separating piece 8 into the valve slide 2.

[0060] Revealed is a directional control valve with a sleeve-shaped valve spool. This spool incorporates a separating piece that is rigidly connected to the valve housing. The separating piece allows the cavities within the valve spool to be fluidically separated from one another. Reference symbol list 1-way valve 2 valve slides 4 valve bores 6 Valve housings 8 separator 10 bolts 12 elongated holes 14 elongated holes 16 Blind hole drilling 18 radial bundle 20 through holes 22 first windows 24 second windows 26 Bridge 28 Bridge 30 first transverse edges 32 second transverse edges 34 third transverse edges 36 fourth transverse edge 38 pens 40 Bridge 42 Bridge 44 Mounting sleeve 46 Housing covers 48 Front surface 50 valve springs 52 pens 54 Case covers 56 bore 58 Channel 60 Front surface 62 Front surface 64 Cavity 66 cavity 68th Chamber 70 Front surface 72nd Chamber 74 first control windows 76 second control windows 78 third control windows 80 fourth control window 82 Fine control notch 84 Cross edge 86 Main Section 88 Front surface 90 Front surface 92 Steg 94 Bridge A first consumer connection B second consumer connection P pressure connection T tank connection

Claims

Hydrostatic directional control valve (1) with a valve housing (6) in which a valve bore (4) is formed in which a valve spool (2) is guided, with which a fluid connection to at least two consumer ports (A, B) can be controlled, characterized in that the valve spool (2) is designed as a sleeve, wherein a fluidic separation between the two consumer ports (A, B) is effected by a separating piece (8) arranged within the valve spool (2) and supported in a fixed position on the valve housing (6). Directional control valve (1) according to claim 1, wherein a housing-fixed retaining element (10) for stationary support of the separating piece (8) is engaged in a recess (20) of the separating piece (8). Directional control valve (1) according to claim 2, wherein the retaining element (10) extends from the valve housing (6) through an opening (12, 14) formed in the valve spool (2) to the recess (20) of the separating piece (8), wherein the opening (12, 14) is designed such that the valve spool (2) is displaceable in the longitudinal direction relative to the retaining element (10) and is substantially secured against rotation. Directional control valve (1) according to claim 3, wherein the separating piece (8) is designed such that it covers the opening (12, 14). Directional control valve (1) according to one of the preceding claims, wherein at least one window (22, 24) is formed on each side of the separating piece (8) in the valve slide (2) for the fluid connection to a respective consumer connection (A, B) via the valve slide (2). Directional control valve (1) according to claim 5, wherein the valve slide (2) is designed to be largely open in the circumferential direction in the area of ​​at least one window (22, 24). Directional control valve (1) according to claim 5 or 6, wherein a plurality of windows (22, 24) are provided for the respective fluid connection to a respective consumer connection (A, B) via the valve slide (2), which are separated from each other in the circumferential direction by webs (26, 28) extending approximately axially. Directional control valve (1) according to one of claims 5 to 7, wherein the separating piece (8) in the valve slide (2) separates two cavities (64, 66) from each other, wherein the windows (22, 24) serve for the fluid connection of a respective consumer port (A, B) with a respective cavity (64, 66), and wherein a control window (74, 76) is provided for controlling a fluid connection between a pressure port P and the respective cavity (64, 66). Directional control valve (1) according to claim 8, wherein at least one further control window (78, 80) is provided for controlling a fluidic connection between the respective cavity (64, 66) and a respective tank connection (T). Directional control valve (1) according to claim 8 or 9, wherein a fine control notch (82) is provided in at least one control window (74, 76, 78, 80). Directional control valve (1) according to one of the preceding claims, wherein a pin (38) is fixed at the end of the valve slide (2), which extends away from the valve slide (2) and can be connected to an actuator for actuating the valve slide (2). Directional control valve (1) according to claim 11, wherein at least one web (42, 40) for fixing the pin (38) is provided at the end of the valve slide (2), extending inwards from an inner surface of the valve slide (2). Directional control valve (1) according to claim 12, wherein a pin (38, 52) is provided at each of the end sections of the valve slide (2), each of which is held by at least one web (40, 42). Directional control valve (1) according to claim 13, wherein an end face (60, 62) of a respective pin (52, 38) corresponds to a respective end face (70, 48) of the valve slide (2). Directional control valve (1) according to one of claims 5 to 14, wherein the windows (22, 24) and / or the control windows (74 - 80) of the valve slide (2) are milled or wire eroded.

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