Abstract:
An electromagnetically actuated valve, in particular a pressure control valve of a slip-controllable vehicle brake system, includes a seat body with a valve seat, at least one inflow channel, and an outflow channel. The valve includes a shut-off element configured to avoid a hydraulic short circuit between the inflow channel and the outflow channel when the valve seat is closed. The shut-off element is equipped with flow-directing means. The flow-directing means prevent the partial flows from the inflow bores from hitting each other and direct the flow to a closing body, which controls the valve seat, in such a way that a transverse force is applied to the closing body when the closing body performs a stroke motion. The transverse force radially deflects the closing body during an opening or closing motion and causes an effect that stabilizes the stroke motion and dampens radial vibrations.

Description:
This application is a 35 U.S.C. § 371 National Stage Application of PCT/EP2014/071439, filed on Oct. 7, 2014, which claims the benefit of priority to Serial No. DE 10 2013 220 331.4, filed on Oct. 9, 2013 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     The disclosure relates to an electromagnetically actuatable valve, in particular a pressure regulating valve of a vehicle brake system with traction control. The design construction of such valves is disclosed, for example, by DE 10 2010 002 469 A1 or DE 10 2011 079 339 A1. These valves comprise a seat body, which in addition to a valve seat forms at least one fluid-ducting inlet port and a fluid-discharging outlet port. In order to prevent a hydraulic short-circuit between these ports when the valve seat is closed, a shut-off element is provided. In the state of the art cited, the shut-off elements used take the form of metal balls, which are pressed into a rising bore downstream of the point where the inlet port enters this rising bore. Metal balls are needed in large quantities, for rolling bearings, for example, and are therefore particularly cost-effective and available on the market in the required quantities and dimensions. 
     The valve seat of these valves is controlled by a closing element. Here the incident flow against this closing element occurs endways through the valve seat. To a large extent this incident flow occurs centrally, so that the fluid flows uniformly or symmetrically past the circumferential surface of the closing element. Tests have shown that oscillations are thereby induced in the closing element in a radial direction, that is transversely to the longitudinal axis of the valve. A disadvantage of these radial oscillations is that they make pressure control through electronic activation of such a valve in a hydraulic system more difficult. That is to say the radial oscillations have a negative influence on a pressure adjustment accuracy of the valve. 
     The aim of the disclosure is to damp these radial oscillations of the closing element through simple design measures that can be cost-effectively implemented on the valve, and indirectly also to improve the pressure adjustment characteristics of a hydraulic system fitted with such a valve. 
     SUMMARY 
     An electromagnetically actuatable valve is equipped with a shut-off element, which comprises flow-directing means. These flow-directing means ensure that the incident flow against the closing element is no longer central or symmetrical but rather eccentric or asymmetrical, so that the flow passes unevenly around closing element. Accordingly, a greater or lesser volume of fluid flows past a segmental portion of the overall circumference of the closing element, depending on the orientation of the flow-directing means relative to the closing element, which consequently produces a resultant transverse force, which deflects the closing element radially in relation to its longitudinal axis when the valve is opened or closed. Since the shut-off element is rigidly anchored in the valve, the transverse force always acts on the closing member in the same radial direction and the closing element is deflected in the same preferred direction by each lifting movement. 
     The flow-generated transverse force exerts a stabilizing influence on the lifting movement of the closing element by damping any excitation of radial oscillations in the closing element. It may be said, therefore, that the lifting movement of the closing element is more controlled than in the state of the art and thereby improves the control characteristics of the valve and of a hydraulic circuit equipped with such a valve. 
     Further advantages or advantageous developments of the disclosure emerge from the dependent claims or the following description. 
     The measures required in order to form flow-directing means according to the disclosure on the shut-off element are technically simple and thereby relatively inexpensive to implement. This applies particularly if the shut-off element is of bolt-shaped design and the flow-directing means are integrally formed with the existing means needed to fix a shut-off element to the seat body. In this case it is even possible just to replace a known shut-off element with a shut-off element according to the disclosure in the course of ongoing series production, without generating additional assembly costs in the process. 
     In valves having a plurality of inlet ports, which open into a common rising bore of the valve body, flow-directing means according to the disclosure can serve to prevent constituent flows from various inlet ports directly colliding with one another and producing unwanted eddying in the overall fluid flow to the closing element. By matching the cross sections of the inlet bores to the dimensions of a gap between the outer circumference of the flow-directing means on the shut-off element and the wall of the rising bore, it is possible to further homogenize and smooth the flow. This also applies for the dimensioning of a geometric distance of the end face of then flow-directing means from the valve seat, and for an angle of inclination at which an end face or a slot of the flow-directing means are inclined in relation to a longitudinal axis of the valve and/or to the manner and way in which this inclined end face is designed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the disclosure are represented in the drawings and described in more detail in the following description. For the overall construction of the valve and its function, reference is made to the disclosures of DE 10 2010 002 469 A1 and DE 10 2011 079 339 A1. 
         FIG. 1  shows a longitudinal section through an electromagnetically actuatable valve known from the state of the art; 
         FIG. 2  shows a longitudinal section of a seat body of this valve, wherein this seat body is equipped with a first exemplary embodiment of a shut-off element; 
         FIG. 3  shows a perspective view of a seat body with shut-off element according to  FIG. 2  inserted and 
         FIG. 4  shows a second exemplary embodiment of a shut-off element according to the disclosure, likewise in a perspective view. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a longitudinal section through an electromagnetically actuatable valve  10  known from the state of the art. For the sake of clarity, a representation of a solenoid that completes this valve  10  was deliberately omitted. The valve  10  comprises a sleeve-shaped valve housing  12 , into the upper, open end of which in  FIG. 1  a plug-shaped pole body  14  composed of magnetically conductive material is inserted. This pole body  14  is firmly connected to the valve housing  12 . A lower, open end of the valve housing  12  in  FIG. 1  is closed by a seat body  16 , which is likewise firmly connected to this valve housing  12 . This seat body  16  forms a valve seat  18 , which is arranged on the longitudinal axis X-X of the valve  10  and is formed at the base of a first counterbore  20  open towards the inside of the valve housing  12 . The valve seat  18  itself is embodied in the form of a conical seat, for example. Opposite the counterbore  20 , open towards the inside of the valve housing  12 , a second counterbore  22 , open outwardly towards the surroundings of the valve  10 , is formed on the seat body  16 . The latter counterbore is situated on a portion of the seat body  16 , the outside diameter of which is reduced compared to the outside diameter of the seat body  16  in the area of the first counterbore  20 . A rising bore  24  running along the longitudinal axis X-X of the valve  10  in the seat body  16  connects the two counterbores  20 ,  22  together. Towards the outwardly open, second counterbore  22  the rising bore  24  is closed by means of a shut-off element  26 . In this exemplary embodiment this is a ball, which is matched to the diameter of the rising bore  24 , in such a way that a press-fit connection can be produced between the shut-off element  26  and the wall of the rising bore  24 . A radially running inlet port  28  opens into the rising bore  24  above the shut-off element  26 . There are multiple such inlet ports  28  in the circumferential direction of the rising bore  24 , this being represented by a circular orifice cross-section above the shut-off element  26  and offset to the left of the longitudinal axis X-X of the valve. The valve seat  18  is situated at the end of the rising bore  24  facing the first counterbore  20 . An outlet port  30  can be seen running radially offset in relation to the rising bore  24  and coaxially with the longitudinal axis X-X of the valve  10 . This outlet port  30  also connects the two counterbores  20 ,  22  together. A filter  32  is attached externally to the seat body  16  at the level of the inlet port  28 . This filter comprises a frame-like filter body (not visible) with openings, which are covered by filter fabric, through which fluid flows into the inlet port  28  of the valve  10 . Where the inlet port  28  opens into the rising bore  24 , this fluid flow is deflected at right-angles, upwards according to  FIG. 1 , and delivered to the valve seat  18 . According to  FIG. 1  this valve seat  18  is closed by a closing element  34 , so that no fluid can pass into a fluid chamber  36  of the valve  10  situated above the valve seat  18  and enclosed by the wall of the first counterbore  20 . Under a lifting movement of the closing element  34 , fluid flows through the valve seat  18  into this fluid chamber  36  and from there passes through a centrally arranged restrictor  38  of a cap-shaped throttle element  40 , which covers the open end of the first counterbore  20 , to a grooved recess  42  in the wall of the first counterbore  20 . This recess  42  provides a fluid-ducting connection between the first fluid chamber  36  and the outlet port  30  of the valve  10 , wherein the fluid flow, after passing through the restrictor  38 , is once again deflected at right-angles and flows downwards out of the valve  10  in the opposite direction to the direction of flow in the rising bore  24  according to  FIG. 1 . 
     The closing element  34  for controlling the valve seat  18  is formed on a tappet  44 , which is inserted by its end, remote from the valve seat  18  and of thicker outside diameter, into an assigned longitudinal recess  46  of a sleeve-shaped valve armature  48 , and is thereby firmly connected to the valve armature  48 . This valve armature  48  is moveably guided in the valve housing  12  in the direction of the longitudinal axis X-X of the valve  10 . In the closed state of the valve  10  represented in  FIG. 1 , a working air gap  54 , in which a washer-shaped flat spring  56  is accommodated, exists between an end face  50  of the valve armature  48  remote from the valve seat  18  and a pole body end face  52  situated opposite this end face  50 . This spring is supported in the area of its outside diameter on the valve armature  48  and in the area of its inside diameter on the pole body  14 . The flat spring  56  therefore provides one of the component forces serving to press the closing element  34  against the valve seat  18  indirectly via the valve armature  48 . A second component force is delivered by a spiral spring  58 , which is accommodated inside the valve armature  48 . This is supported, on the one hand, on the widened end of the tappet  44  holding the closing element  34 , and on the other indirectly via a support bushing  60  on the pole body end face  52 , the support bushing  60  protruding through a central opening of the washer-shaped flat spring  56 . 
     A solenoid, not shown in  FIG. 1 , which can be electrically energized, is fitted onto the valve housing. A magnetic flux occurring when this solenoid is energized produces magnetic attraction forces between the valve armature  48  and the pole body  14 , causing the valve armature  14  to move upwards according to  FIG. 1  towards the pole body  14 , so that the working air gap  54  originally existing between these components is reduced. Since the closing element  34  is firmly connected to the valve armature  48 , the lifting of the valve armature  48  causes the closing element  34  to lift off from the valve seat  18 , thereby hydraulically connecting the inlet port  28  to the outlet port  30  via the fluid chamber  36 , the restrictor  38  of the throttle element  40  and the recess  42 . 
     The lifting movement of the valve armature  48  occurs in opposition to the return forces of the flat spring  56  and the spiral spring  58 , which are further pre-tensioned as a result of the lifting movement. With the withdrawal of an electrical current from the solenoid and the cessation of the magnetic forces, these spring forces cause the valve armature  48  to return to the basic position shown in  FIG. 1 , which is evidenced by the closing element  34  being mechanically pressed onto the valve seat  18 , thereby interrupting the fluid connection of the inlet port  28  to the outlet port  30 . 
       FIG. 2  shows a longitudinal section of the seat body  16  of the valve  10  with a shut-off element  26  formed according to the disclosure. The geometry of the seat body  16  corresponds to that of the valve  10  according to  FIG. 1 , for which reason components fulfilling the same function are provided with the same reference numerals as in  FIG. 1 . 
     In contrast to  FIG. 1  this seat body  16  is provided with a first embodiment of a shut-off element  26 . 1  according to the disclosure. This shut-off element  26 . 1  is of bolt-shaped design and comprises a cylindrically shaped fixing portion  70  and a likewise cylindrical flow-directing portion  72 . 1  arranged coaxially with the fixing portion  70 . The fixing portion  70  and the flow-directing portion  72 . 1  are integrally formed with one another, the fixing portion  70  having a larger outside diameter than the flow-directing portion  72 . 1 . A transition from the fixing portion  70  to the flow-directing portion  72 . 1  is formed as a right-angled shoulder  82 , for example. With the fixing portion  70  the shut-off element  26 . 1  is pressed into the rising bore  24  from the second counterbore  22  of the seat body  16 , and with the valve seat  18  closed thereby prevents a hydraulic short-circuit between at least the one inlet port  28  and the outlet port  30 . Towards the inside of the valve housing  12  the flow-directing portion  72 . 1  adjoins the fixing portion  70  and at least in some areas covers that area of the seat body  26 . 1  at which the inlet port or inlet ports  28  open(s) into the rising bore  24 . A wider or narrower annular gap  74 , into which the inlet ports  28  open, is formed between the components, depending on the outer circumference of the flow-directing portion  72 . 1  and the inner circumference of the wall of the rising bore  24 . The annular gap  74  or an axial coverage of the orifice cross sections of the inlet ports  28  by the flow-directing portion  72 . 1  of the shut-off element  26 . 1  prevents incoming fluid flows from various directions colliding directly with one another and forming a highly turbulent overall fluid flow, which is ultimately incident upon the closing element  34  of the valve  10 . A front-face end  76  of the flow-directing portion  72 . 1  of the shut-off element  26 . 1  is inclined in relation to the longitudinal axis X-X of the valve  10  and the seat body  16  at an angle of inclination that can be fixed for a specific application. For example, the front-face end  76  forms a plane inclined face. It would be equally feasible, however, instead of making the front-face end  76  plane, to design it with a convex or concave or spherical shape. 
     It is possible, via the shaping and/or inclination of the front-face end  76  of the flow-directing portion  72 . 1  in relation to the longitudinal axis X-X of the valve  10 , and the axial length and the diameter of the flow-directing portion  72 . 1  of the shut-off element  26 . 1 , to direct the incident fluid flow against the closing element  34  ( FIG. 1 ) in such a way that this incident flow is eccentric or asymmetrical, and the valve armature  48  is thereby subjected to a stabilizing, transverse force damping any radial oscillations, when under magnetic force it performs a lifting movement. 
     For greater ease of understanding,  FIG. 3  in a perspective view again shows a seat element  16  with shut-off element  26 . 1  according to the disclosure. The reference numerals from  FIGS. 1 and 2  are adopted for corresponding components. More clearly visible in this representation are the valve seat  18  and the recess  42  in the wall and at the base of the first counterbore  20  intended to represent a fluid-ducting connection of this counterbore  20  to the outlet port  30  of the seat body  16 , not visible here 
     In contrast to the exemplary embodiment according to  FIGS. 2 and 3 , in the second exemplary embodiment according to  FIG. 4  the bolt-shaped shut-off element  26 . 2  is provided with a cylindrical, flow-directing portion  72 . 2 , which has a horizontal, plane front-face end  76 . 2  and in addition is provided with a grooved slot  78 . Its slot width is of smaller dimension than the outside diameter of the flow-directing portion  72 . 2 , so that the slot  78  is defined on both sides by remaining circumferential segments of the flow-directing portion  72 . 2 . The slot  78  extends over the entire length of the flow-directing portion  72 . 2  and is open at the side. The slot depth of the slot  78  increases continuously with increasing distance from the fixing portion  70 , so that the slot base  80  forms a plane, inclined face, the angle of inclination of which in relation to the longitudinal axis X-X of the shut-off element  26 . 2  can be fixed for a specific application. The slot  78  has a flow-directing effect comparable to the inclined front-face end  76 . 1  of the shut-off element  26 . 1  according to  FIGS. 2 and 3 , in that it also ensures that the incident flow against the closing element  34  ( FIG. 1 ) of a valve  10  equipped with a shut-off element  26 . 2  of such a design is eccentric or asymmetrical. As already explained, the asymmetrical incident flow on the closing element  34  produces a transverse force damping radial oscillations and stabilizing the lifting movement of the valve armature  48  ( FIG. 1 ). 
     Modifications or additions to the exemplary embodiments described are obviously feasible without departing from the basic idea of the disclosure.