Abstract:
The invention relates to a damping valve, in particular for shock absorbers of vehicles, with an adjustable damping force, in which differently sized outlet openings arranged between an inflow and an outflow can more or less be closed in order to obtain a desired damping effect. To this end, the differently sized outlet openings are more or less sealed off radially by means of a valve slide. In another embodiment, sudden pressure increases in the damping valve are automatically reduced by means of a differential area function. Due to said invention, said damping valve can be produced easily, has low leakage loss, a low tolerance chain and requires little effort for setting the desired damping.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority International Patent Application PCT/DE2012/100042, filed on Feb. 6, 2013 and German Patent Application 10 2012 201 963.4, filed on Feb. 9, 2012. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    No federal government funds were used in researching or developing this invention. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       SEQUENCE LISTING INCLUDED AND INCORPORATED BY REFERENCE HEREIN 
       [0004]    Not applicable. 
       BACKGROUND 
       [0005]    1. Field of the Invention 
         [0006]    The present invention relates to a damper valve, in particular for shock absorbers of vehicles, with adjustable damping force 
         [0007]    2. Background of the Invention 
         [0008]    The current state of knowledge is as follows. 
         [0009]    Such damper valves are well known and regularly show an electromagnet, by which a valve slide is moved in order to close the outlet opening located between an inlet and an outlet to a greater or lesser extent and this way ensuring a throttle effect. When the outlet opening is open to a relatively large extent we create a comfortable chassis. If the vehicle shall be provided with a “hard” chassis, the throttling is increased, i.e. the outlet opening is closed to a greater extent. This way a sporty chassis can be achieved and better stabilization of the vehicle at high speeds. 
         [0010]    An example for such an electromagnetically controlled damper valve is described in DE 41 08 026 A1. Here, the damper valve is embodied as a one-stage and/or two-stage slide valve, with the slide position being determined depending on the hydraulic pressure difference generated over the damper valve, the flow rate flowing through the damper valve, as well as the control current of the electromagnetic actuation. In this damper valve the fact is problematic that the valve slide, embodied in a sheath-like fashion, is coupled with an inductor which is moved together with the valve slide for a sectional closing of the outlet opening and thus for achieving the throttle effect. This leads to a very complicated design and additionally is prone to malfunction, due to the axial motion of the coil. 
         [0011]    Furthermore, damper valves are known in which the electromagnet is arranged stationary inside the housing of the damper valve. Here, the rotor present in the electromagnet is connected to an exterior valve slide. However, in order to be supported this cylindrically designed exterior valve slide must encompass a bearing part located inside the exterior valve slide. Here, depending on the axial position of the exterior valve slide a particularly shaped outlet opening is closed more or less at its front by the exterior valve slide. In such a damper valve on the one hand the large number of components is problematic, and on the other hand the fact that any tilted position of the exterior valve slide can lead to jamming and thus malfunctioning of the damper valve. Accordingly these damper valves of prior art need to be produced with large internal play. Overall it has shown that these damper valves are characterized in high leakage loss. Additionally it is problematic that, in order to achieve a hyperbolically increasing control curve, i.e. the ratio between rotor stroke and cross-section of the opening, a very complex and thus complicated geometric shape of the outlet opening must be selected, which is also very expensive and aggravates the production of such damper valves. Overall, due to the complex components here increased expenses are necessary both for the assembly as well as the adjustment of the damper valve. 
         [0012]    The objective of the present invention therefore comprises to provide a damper valve, in particular for shock absorbers of vehicles, such that on the one hand it can be produced more easily and is characterized in low leakage loss and a small number of components. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    In a preferred embodiment, a damper valve, in particular for shock absorbers of vehicles, with adjustable damping force, in which via an electromagnet an outlet opening, located between an inlet and an outlet, can be closed to a greater or lesser extent by a valve slide, wherein at least two outlet openings are provided, showing different sizes and each embodied as bores, and that these outlet openings can be radially sealed to a greater or lesser extent by the valve slide depending on the desired throttle effect. 
         [0014]    The damper valve as described herein, wherein the outlet openings are circular bores. 
         [0015]    The damper valve as described herein, wherein four outlet openings are provided, with these four outlet openings being arranged at an angle of 90° in reference to each other. 
         [0016]    The damper valve as described herein, wherein two equally sized outlet openings are each located diametrically opposite each other. 
         [0017]    The damper valve as described herein, wherein the differently sized outlet openings are arranged with the center of their openings at the same axial height in reference to the central axis of the damper valve. 
         [0018]    The damper valve as described herein, wherein the differently sized outlet openings are arranged in reference to the valve slide such that the large outlet opening can only be opened by the valve slide when the small outlet valves have already been opened by the valve slide. 
         [0019]    The damper valve as described herein, further comprising wherein a hydraulic return is provided from the outlet in the direction towards the rotor. 
         [0020]    The damper valve as described herein, further comprising wherein a control pin is loosely inserted between the rotor and the valve slide. 
         [0021]    The damper valve as described herein, wherein the control pin shows a diameter of less than 1 mm, preferably from 0.6 to 0.8 mm. 
         [0022]    The damper valve as described herein, further comprising wherein a compensation bore is provided in the rotor, penetrating said rotor. 
         [0023]    The damper valve as described herein, wherein the valve slide is embodied like a cup and shows at its bottom a compensation bore penetrating the bottom of the valve slide. 
         [0024]    The damper valve as described herein, further comprising wherein a valve seat is provided, in which the differently sized outlet openings are arranged and in which the valve slide is guided. 
         [0025]    The damper valve as described herein, further comprising wherein a compensation bore is arranged in the valve seat, arranged from the outlet in the direction towards the rotor. 
         [0026]    The damper valve as described herein, wherein the valve seat shows a collar pointing away from the rotor, in which an adjustment disk is fixed, which pushes via the spring device against a facial end of the valve slide. 
         [0027]    The damper valve as described herein, further comprising wherein a sheath is arranged between the valve seat and the valve slide, in which the different outlet openings are implemented. 
         [0028]    The damper valve as described herein, wherein four circular outlet openings are arranged in the sheath, with two outlet openings of equal size each being located diametrically opposite each other. 
         [0029]    The damper valve as described herein, wherein the valve slide is embodied as a hollow cylinder and provided with bores. 
         [0030]    The damper valve as described herein, wherein the valve seat shows a channel from its outlet towards the outlet openings of the sheath which has a greater cross-section than the outlet openings. 
         [0031]    The damper valve as described herein, wherein it is embodied as a normally closed damper valve. 
         [0032]    The damper valve as described herein, wherein it is embodied as a normally open damper valve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIG. 1  is a line drawing evidencing a first exemplary embodiment of the damper valve with differently sized outlet openings, inserted in a valve seat, as well as a control pin. 
           [0034]      FIG. 2  is a line drawing evidencing a second exemplary embodiment of a damper valve according to the invention with a sheath arranged about the valve slide, in which differently sized outlet openings are inserted, as well as showing a differential area provided with a valve slide. 
           [0035]      FIG. 3  is a line drawing evidencing the magnified detail D shown circular in  FIG. 2  in an area of the differential area. 
           [0036]      FIG. 4  is a line drawing evidencing as an example the characteristic progression of rotor stroke/open cross-section of the valves of  FIG. 1  and  FIG. 2 . 
           [0037]      FIG. 5  is a line drawing evidencing as an example the differently sized, circular outlet openings provided, shown in a blank. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    The idea of the present invention essentially comprises that at least two differently sized outlet openings are provided, embodied as bores, which can be closed radially by valve slides to a greater or lesser extent, depending on the desired throttle effect. In such a damper valve very complex contours of the outlet openings are no longer necessary. Rather it is sufficient to provide circular and thus easily produced bores with differently large diameters. Here, the outlet openings may be arranged axially offset from each other, in reference to a central axis of the damper valve. By selecting the diameter of the bores most different cross-sections of the throttle can be created. 
         [0039]    It has proven beneficial to provide four outlet openings, with these outlet openings being distributed preferably each at an angle of 90° in reference to each other. Two identically sized outlet openings each are here arranged diametrically opposite each other. 
         [0040]    In order to generate a beneficial characteristic regarding the ratio of rotor stroke/overall open cross-section of the outlet openings it has proven beneficial to arranged all or some of the outlet openings with the center of their opening axially off-set from each other in reference to a central axis X of the damper valve. 
         [0041]    However it may also be provided that the centers of the outlet openings are offset in reference to each other. Here, it should be observed that preferably the differently sized outlet openings are arranged in reference to the valve slide such that the large outlet opening or the large outlet openings are only opened by the valve slide when the small outlet opening or the small outlet openings have already been opened by the valve slide. 
         [0042]    Furthermore it has proven advantageous to provide a control pin between the rotor and the valve slide by which in case of a sudden pressure increase inside the damper valve a greater flow rate is permitted, reducing the pressure and thus sudden pressure peaks, as occurring e.g. when driving over a pothole, being better absorbed. A similar effect is achieved when instead of such a control pin the valve slide is provided with a circumferential difference area, i.e. an enlarged exterior diameter, in order to generate a differential area function. This is discussed in greater detail in the description of the figures. 
         [0043]    In one exemplary embodiment of the invention it is provided that the differently sized outlet openings are provided in a housing part of the damper valve, preferably the valve seat. However, instead thereof a sheath may be arranged about the valve slide, in which these outlet openings are inserted, with here it being necessary to observe that a sufficiently large channel is provided from the outlet openings of this sheath to the outlet chamber of the damper valve. 
       DETAILED DESCRIPTION OF THE FIGURES 
       [0044]      FIG. 1  shows a first exemplary embodiment of a damper valve  1 . The damper valve  1  shows a central axis X. Centered in reference thereto, a cup-shaped metallic pole core  12  is arranged at the left side in  FIG. 1 . This pole core  12  is followed by a metallic annular body  14 . At the right of this annular body  14  the valve seat  30  is found, made from metal, to be explained in greater detail in the following. Inside the pole core  12  there is a rotor  18 , which is provided with a compensation bore  19  penetrating the entire length of the rotor  18 . 
         [0045]    On the exterior wall of the pole core  12  and the annular body  14  as well as a part of the valve seat  30  a bobbin  21 , made from plastic, is located rotationally symmetrical. This bobbin  21  carries a coil  20 , which is electrically connected to a plug-in connector  22 . Electricity can be supplied via this plug-in connector  22  to the coil  20  in order to axially move the rotor  18  according to the power supplied. Together with the pole core  12  and the rotor  18  the coil  20  forms an electromagnet. The entire coil  20  and the bobbin  21  are provided with a plastic coating  28 , which additionally also surrounds the plug-in connector  22  like a collar. 
         [0046]    At the left side of the damper valve  1  a metallic back-iron  24  is provided, which also acts as a left housing lid. The coil  20  and the plastic coating  28  are surrounded by a cylindrical housing wall  26 . At the right of this cylindrical housing wall  26  a plate-shaped section of the valve seat  30  follows, which acts as the right housing lid. 
         [0047]    The valve seat  30  shows a staggered penetrating bore along the central axis X. A cup-shaped valve slide  40  is located approximately in the middle of the valve seat  30 . The cup-shaped opening of the valve slide  40  is marked with the reference character  42 . A compensation bore  44  is located in the bottom wall of the valve slide  40 , penetrating the entire bottom parallel in reference to the central axis X. For example, two or more such compensation bores  44  are inserted in the bottom of the valve slide  40 . At the left of the valve slide  40  the valve seat  30  shows a penetrating bore with a relatively small diameter, in which a control pin  60  is arranged axially guided. The control pin  60 , which shows e.g. a diameter of 1 mm or less, thus for example 0.6 mm to 0.8 mm, is placed centered on the central axis X and thus with its left end contacts the rotor  18  at its face and with its right end contacts the bottom of the valve slide  40  at its face. 
         [0048]    Shown in  FIG. 1 , the valve seat  30  comprises an expanding annular flange at its right side, in which an adjustment disk  50  is fixed, for example by beading. A spring device  52  is supported with one end at this adjustment disk  50  and with its other end at a circumferential step of the right facial end of the valve slide  40 . The damper valve  1  shows an inlet Z at the right side, which is inserted with an outlet A via several outlet openings, embodied as circular bores in the wall of the valve seat  30 . In the present exemplary embodiment four such outlet openings are provided. The outlet openings are designed as circular bores, with the bores showing different sizes. The two smaller ones, which represent outlet openings located diametrically opposite each other, are marked with the reference character  31 . The slightly larger outlet openings (are marked) with the reference character  32 , with here the outlet opening facing the observer not being discernible due to the cross-sectional illustration of  FIG. 1 . Accordingly, only the outlet opening  32  appearing behind the spring device  52  in the illustration of  FIG. 1  is shown here, half-way covered and facing away from the observer. 
         [0049]    The cylindrical exterior wall of the valve slide  40  serves for the radial sealing and/or partial sealing of the above-mentioned outlet openings  31 ,  32  and leads this way to a throttle effect, depending to what extent the valve slide  40  is moved from the left to the right in the illustration of  FIG. 1 . The motion of the valve slide  40  occurs here by respective power supply of the field coil  20 , causing the rotor  18  to move to the right. Here, the rotor  18  slides the control pin  60  towards the right as well, which in turn moves accordingly the valve slide  40  towards the right and this way ensures the desired throttle effect. 
         [0050]    For reasons of completeness, it shall be mentioned that the valve seat  30  comprises a compensation bore  33 , which connects the outlet A to the chamber in which the rotor is moving and ensures pressure compensation. 
         [0051]    The arrangement of the differently sized four outlet openings  31 ,  32  is discernible in the context with  FIG. 5 . Here, the outlet openings  31 ,  32  of  FIG. 1  are shown once more graphically in a blank. The outlet openings  31 ,  32  are located with their center axially offset in reference to the central axis X of the damper valve  1 . The valve slide  40  is also shown schematically in a blank and indicated in dot-dash lines in  FIG. 5 . The valve slide  40  is located in  FIG. 5  precisely in the position in which it completely covers the smaller outlet openings  31  and thus closes them entirely. It is clearly discernible that a complete opening of the larger outlet openings  32  can only occur when the valve slide  40  has already released the small outlet openings completely by a motion towards the left. 
         [0052]    With such an arrangement of four circular outlet openings  31 ,  32 , which are differently sized in pairs, for example the hyperbolic control curve shown in  FIG. 4  can be achieved. In the control curve shown the dependence of the cross-section of the opening is shown in reference to the rotor stroke of the rotor  18 . Here, the combined open cross-section of all four outlet openings  31 ,  32  is called the open cross-section. 
         [0053]    Although it was mentioned in the context with  FIG. 5  that the centers of the four outlet openings  31 ,  32  are located on the same axial height in reference to the central axis X of the damper valve  1 , this is not mandatory. The centers may also be located offset in reference to each other. Here it is only essential that a complete closing and/or opening of the smaller outlet openings  31  and the larger outlet openings  32  can only occur consecutively. 
         [0054]    Furthermore, the scope of the invention includes that more than four outlet openings are provided or three or four differently sized outlet openings are implemented in the damper valve  1 . It is essential for the invention that the outlet openings are embodied as simple, preferably circular bores. 
         [0055]    The assembly of the damper valve  1  shown in  FIG. 1  is particularly simple and occurs from the left towards the right. First the pole core  12  with the metallic annular body  14  is inserted between the coil body  21 . Subsequently the rotor  18  is inserted into the pole core  12 . The control pin  60  and the valve slide  40  are inserted into the valve seat  30 . Subsequently the valve seat  30  equipped in this fashion is pushed in the direction towards the rotor  18 . Finally the spring device  52  is placed upon the right face of the valve slide  40  and fixed via the adjustment disk  50 . The axially correct positioning of the adjustment disk  50  occurs here in a particular measuring step during the assembly of the damper valve  1 , in order to adjust a certain operating point of the damper valve  1 . When the operating point has been set, the adjustment disk  50  is fastened at the circumferential collar of the valve seat  30 , for example by beading or the like. 
         [0056]    The operation of the damper valve  1  shown in  FIG. 1  is as follows. Here it shall be observed that the entire damper valve  1  is pressure compensated. This means that the pressure applied in the inlet Z inside the valve slide  40  and, due to the bore  44  provided here in the bottom, is also applied at the left between the wall of the valve seat  30  and the bottom of the valve slide  40 . The rotor  18  is also pressure compensated via the channel  33 , which due to the compensation bore  19  connects the space at the right and the left of the rotor  18  and the channel  33  located in the valve seat  30 . 
         [0057]    The adjustable damper force of the damper valve  1  is achieved by axially sealing the outlet openings  31 ,  32  to a greater or lesser extent using the radial exterior area of the valve slide  40 . In  FIG. 1  the valve slide  40  is shown in its position as far left as possible. In this position the four outlet openings  31 ,  32  are radially sealed to a relatively small extent by the valve slide  40 . When power is supplied to the coil  20  the rotor  18  moves towards the right, causing the control pin  60  to move the valve slide  40  towards the right as well in order to further close the outlet openings  31 ,  32 . 
         [0058]    If the vehicle shall be provided with a “hard chassis” the throttling is increased and thus the entire cross-section of the outlet openings  31 ,  32  is reduced. This way a sporty chassis can be yielded or better stabilization at high speeds. For a comfortable chassis and a soft damping the throttling is reduced and a larger cross-section of the outlet openings  31 ,  32  is adjusted, for example by the position of the valve slide  40  as far as possible to the left as shown in  FIG. 1 . 
         [0059]    With the damper valve  1  of  FIG. 1  it is possible, due to the control pin  60  used and the provided compensation bores  19 ,  44 , and  33 , that in case of a sudden pressure increase briefly a larger flow rate is released through the outlet openings  31 ,  32 , resulting in the pressure reducing and sudden pressure increases being considerably better compensated, which occur for example when driving over a pothole. In case of a sudden pressure increase here the control pin  60  pushes the rotor  18  towards the left, allowing the valve slide  40  to move towards the left as well. Of course it is conditional that both the rotor  18  including the control pin  60  and the valve slide  40  are not in the initial position shown in  FIG. 1  but are overall located slightly towards the right by power being applied to the coil  20 . 
         [0060]      FIG. 2  shows a second exemplary embodiment of a damper valve. The already known reference characters are used again for the same parts. The electromagnetic system comprising the coil  20 , the pole core  12 , the metallic annual body  14 , and the plastic coating  28  including the plug connector  22  is equivalent to the one of  FIG. 1 , as well as the adjustment disk  50  and the corresponding spring device  52 . 
         [0061]    The damper valve  1  differs in the following areas from the damper valve of  FIG. 1 . The compensation bore  19  is now located centered in reference to the central axis X and is therefore located in the central axis of the rotor  18 . As clearly discernible in  FIG. 2 , here the control pin discussed in  FIG. 1  is missing. Rather, now a tubular designed valve slide  40  directly abuts the face of the rotor  18  shown at the right in  FIG. 2 . As already known from  FIG. 1 , the spring device  52 , embodied as a flat spring, is supported with one end at the right side of the valve slide  40  and with its other end at the adjustment disk  50 . The valve slide  40  shows a plurality of preferably circular bores  41 , so that the pressure medium can flow from the inlet Z into the valve slide  40  and discharge via the above-mentioned bores out of the valve slide at the outlet A. The circumferential wall of the valve slide  40  serves again for the radial sealing of outlet openings  31 ,  32 , which are here not implemented directly in the valve seat  30  but in a tubular sheath  70 , located coaxial on the valve slide  40 , preferably made from metal. 
         [0062]    Here, too, preferably four outlet openings  31 ,  32  are inserted in this sheath  70 . The outlet openings  31 ,  32  are located at an angle of 90° in reference to each other. In  FIG. 2  the two larger outlet openings  31  are discernible in a cross-section, located diametrically opposite each other, while one of the two smaller outlet openings  32 , also located diametrically opposite each other, is discernible only partially through the bores  41  of the valve slide  40  and carries the reference character  32 . It is discernible that the right edge of the two larger outlet openings  31 , in  FIG. 2  at the right, is located in reference to the central axis X of the damper valve  1  slightly further to the right than the right edge of the smaller outlet opening  31 . A channel  34  is inserted into the valve seat  30 , starting at these outlet openings, which leads to the bores  35  of the outlet A of the damper valve  1 . The channel  34  and the bores  35  are here sized such that they show a greater combined diameter than the outlet openings  31 ,  32 . 
         [0063]      FIG. 2  shows the damper valve in the initial position of the stroke. The outlet openings  31 ,  32  are partially covered by the circumferential exterior wall of the valve slide  40 . When power is supplied to the coil  20  the rotor moves towards the right and thus pushes the valve slide  40  towards the right as well so that the outlet openings  31 ,  32  are further closed and the desired throttle effect occurs. 
         [0064]    The differential area function realized in  FIG. 1  via the control pin  60  is achieved in the exemplary embodiment of  FIG. 2  via a staggered exterior contour of the valve slide  40 . This detail is marked D in  FIG. 2  and shown enlarged in  FIG. 3 . The valve slide  40  shows an annularly extending projection  46  at its end facing the spring device  52 , which is surrounded by a circumferential recess  72 , showing a sickle-like shape in its cross-section, inserted in the sheath  70 . Additionally, a compensation bore  37  is implemented in the sheath  70 , extending radially in reference to the central axis X. As shown in  FIG. 2 , several such compensation bores  37  may be provided.  FIG. 2  shows two such compensation bores  37  in the sheath  70  in the cross-sectional illustration. The compensation bore  37  is connected to the channel  34  and thus also to the bore  35  leading to the outlet A of the valve seat  30 . At the end shown in  FIG. 3  at the bottom this compensation bore  37  transfers into the sickle-shaped recess  72 . This way, the same pressure as in the outlet A is applied to both the compensation bore  37  as well as the sickle-shaped recess  72 . 
         [0065]    If for example the damper valve  1  in  FIG. 2  is adjusted to a “hard” chassis, the valve slide  40 , due to the appropriate field coil  20  and the axial motion of the rotor  18  connected thereto, moves to the right to a position in which the outlet openings  31 ,  32  of the sheath  70  are closed to a greater extent than in the position shown in  FIG. 2 . In case of a sudden pressure increase in the inlet Z, as possible when driving over a pothole, the differential area of the valve slide  40  formed by the annular projection  46  can briefly push the rotor  18  by the force applied here towards the left so that a greater flow-rate is released in the outlet openings  31 ,  32 . This way the pressure can be reduced so that the impact upon the chassis is considerably better compensated. 
         [0066]    The arrangement in  FIG. 2  is advantageous in that the entire damper valve  1  can be constructed with a shorter axial length than the arrangement of  FIG. 1 . 
       LIST OF REFERENCE CHARACTERS 
       [0000]    
       
           1  Damper valve 
           12  Pole core 
           14  Annular body 
           18  Rotor 
           19  Compensation bore 
           20  Coil 
           21  Coil support 
           22  Plug-in connector 
           24  Back-iron 
           26  Cylindrical housing wall 
           28  Plastic coating 
           30  Valve seat 
           31  First outlet opening 
           32  Second outlet opening 
           33  Compensation bore 
           34  Channel 
           35  Bore 
           37  Compensation bore 
           40  Valve slide 
           41  Bore 
           42  Recess 
           44  Bore 
           46  Projection 
           50  Adjustment disk 
           52  Spring device 
           60  Control pin 
           70  Sheath 
           72  Central axis 
         A Outlet 
         B Detail 
         D Detail 
         X Central axis 
         Z Inlet 
       
     
         [0100]    The references recited herein are incorporated herein in their entirety, particularly as they relate to teaching the level of ordinary skill in this art and for any disclosure necessary for the commoner understanding of the subject matter of the claimed invention. It will be clear to a person of ordinary skill in the art that the above embodiments may be altered or that insubstantial changes may be made without departing from the scope of the invention. Accordingly, the scope of the invention is determined by the scope of the following claims and their equitable equivalents.