Abstract:
A device for controlling the flow of a liquid or gaseous medium, has at least one flow opening for the medium, and a movable valve element for controlling the flow opening. At least one damping body, which is preferably viscoelastic and acts on the valve element, is provided for obtaining a large dynamic range of the device in order to control flow in a fine, precise, and oscillation-free manner across a broad range of flow volume.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The invention described and claimed hereinbelow is also described in European Patent Application EP 10 006 531.7 filed on Jul. 23, 2010. This European Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a device for controlling the flow of a liquid or gaseous medium. 
         [0003]    A known device for controlling the flow of a liquid or gaseous medium (EP 1 536 169 A1) includes a 2/2 directional control valve having a valve element that controls a valve opening through which the medium can flow, and an electromagnet that actuates the valve element. The valve element is disposed in a valve chamber formed in a valve housing; the valve opening, which is situated between a valve inlet and a valve outlet, is formed in the valve chamber. The valve opening is enclosed by a valve seat with which the valve element interacts to close and open the valve opening. The electromagnet includes a magnetic circuit having a solenoid coil or excitation coil, an armature sleeve that accommodates the solenoid coil on the outside and is closed by an armature plug, and a solenoid armature that is guided in the interior of the armature sleeve. 
         [0004]    The solenoid armature is held, in an axially displaceable manner, in the armature sleeve using two flat springs disposed on the upper and lower end faces; together with the armature plug, the solenoid armature limits a working air gap contained in the magnetic circuit. The armature sleeve protrudes into the valve chamber. The point of entry is sealed against the valve housing by a sealing ring. The valve element includes a sealing holder having a plug, which is inserted axially into the solenoid armature, and a sealing plate that is accommodated in the sealing holder and interacts with the valve seat. The closed state of the valve is brought about by a valve closing spring that acts on the solenoid armature; the valve closing spring is disposed in a blind hole in the solenoid armature, bears against the armature plug, and presses the sealing plate against the valve seat. 
         [0005]    When current is supplied to the electromagnet, the solenoid armature is displaced axially against the spring force of the valve closing spring, and the solenoid armature lifts the valve element off of the valve seat, thereby opening the valve opening and, depending on the lift of the valve element, a larger or smaller volume of medium flows from the valve inlet via the valve chamber to the valve outlet. The valve chamber is filled continually with medium, and so the medium constantly flows around the valve element and the end face of the solenoid armature. 
       SUMMARY OF THE INVENTION 
       [0006]    The problem addressed by the invention is that of providing a device for controlling the flow of a liquid or gaseous medium, that has a large dynamic range and therefore makes it possible to control the flow of extremely different flow volumes of the medium in a fine, precise, and oscillation-free manner. 
         [0007]    In keeping with these objects and with others which shall become apparent hereinafter, one feature of the present invention resides, briefly stated in a device for controlling a flow of a medium selected from the group consisting of a liquid medium and a gaseous medium, comprising at least one flow opening for the medium; a movable valve element for controlling said flow opening; and at least one damping body acting on said valve element. 
         [0008]    The device according to the invention has the advantage that, due to the at least one damping body that is preferably viscoelastic, acts on the movable valve element, and is composed e.g. of a gel-type material, the valve element is damped in a speed-dependent, “dynamic” manner as it moves in a reciprocating manner, thereby preventing the flow from fluctuating. 
         [0009]    Smaller changes in flow are implemented with little delay. When flow volumes are greater, oscillations of the valve element during flow control are prevented. The attainable dynamic range is greater than 1:2000. Gel damping prevents the transition from stiction to kinetic friction i.e. “stick slip”. In contrast to friction damping, gel damping does not result in greater hysteresis. Examples of the gel-type material that is advantageously used for the damping body are e.g. polyurethane gel and silicone gel. Other damping means or other damping material can also be used for the damping body. 
         [0010]    According to an advantageous embodiment of the invention, the movable valve element includes a sealing element that interacts with a valve seat that encloses the at least one flow opening, and includes a solenoid armature—which is fixedly connected to a sealing element—of an electromagnet and a bearing element that is fixedly connected to the solenoid armature and/or sealing element in order to support the valve element with minimal friction. The at least one damping body that acts on the valve element can act directly or indirectly on one of the movable valve element parts e.g. on the solenoid armature and/or on the sealing element and/or on its bearing element. As a result, a large number of possibilities exist for integrating the at least one damping body in a structurally appropriate manner, with consideration for structural conditions inside the device. The damping body is disposed such that it is exposed to compression pressure when the sealing element lifts off of the valve seat. 
         [0011]    According to an advantageous embodiment of the invention, the valve element extends into a valve chamber formed in a valve housing; a flow opening and valve seat are formed in the valve chamber. The damping body can be disposed in the valve chamber and can bear e.g. against the chamber wall. 
         [0012]    According to an advantageous embodiment of the invention, the bearing element is formed by a flat spring that is situated in the valve chamber. The flat spring is secured in the valve housing on the edge, while the sealing element and solenoid armature are fastened in the center on the flat spring. In this case, it can be advantageous in terms of design that the at least one damping body acts e.g. on the flat spring and bears against the flat spring on one side and, on the other side, against the wall of the valve chamber opposite the flat spring. To optimize the damping, a plurality of damping bodies, which are disposed e.g. at identical circumferential angles relative to each other, can be situated in the valve chamber in the manner described. 
         [0013]    According to an advantageous embodiment of the invention, the flat spring is preloaded toward the valve seat and, together with an adjustment spring that acts on the solenoid armature, influences the closing force of the valve element. 
         [0014]    The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  a longitudinal sectional view of a device for controlling the flow of a liquid or gaseous medium according to the present invention, 
           [0016]      FIG. 2  a top view of a flat spring, on which damping bodies are placed, in the device according to the present invention shown in  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    The device, which is shown as an example in a longitudinal sectional view in  FIG. 1 , for controlling the flow of a liquid or gaseous medium which is also referred to as a fluid, flowing, or streaming medium, includes at least one flow opening  11  for the medium, and a movable valve element  12  for controlling flow opening  11 , wherein preferably at least one viscoelastic damping body  13  acts on valve element  12  to control the flow of the medium through flow opening  11  in a fine, precise manner despite very different flow volumes. 
         [0018]    Valve element  12 , which is actuated by an electromagnet  14 , includes a solenoid armature  15  of electromagnet  14 , a sealing element  16  which interacts with a valve seat  17  that encloses flow opening  11  to control flow opening  11 , and a bearing element  18  for supporting valve element  12  in a low-friction or largely frictionless manner, wherein solenoid armature  15 , sealing element  16 , and bearing element  18  are movable parts that are securely interconnected, and the at least one damping body  13  acts on one of these valve element parts. Damping body  13  is disposed such that it is exposed to compression pressure when sealing element  16  lifts off of valve seat  17 . Damping body  13  is composed e.g. of a gel-type material, wherein e.g. polyurethane gel or silicone gel can be used. 
         [0019]    Structurally, the device is composed of a valve  19  and electromagnet  14  which actuates valve  19 . In the embodiment depicted in  FIG. 1 , valve  19  is designed as a 2/2 directional control valve, although it can also be designed e.g. as a 3/2 directional control valve. Valve  19  includes a two-pieced valve housing  20  that is composed of a valve body  21  and a valve cover  22  that closes valve body  21 . A valve chamber  23  is provided in valve housing  20 , the chamber walls of which are formed by valve body  21  and valve cover  22 . Valve seat  17 , which encloses flow opening  11 , is formed on valve body  21  in valve chamber  23 . Valve chamber  23  is connected via a first channel  24 , which extends toward flow opening  11 , to a first valve connection  25 , and is connected via a second channel  26  to a second valve connection  27 . Channels  24 ,  26  are formed in valve body  21 . 
         [0020]    Electromagnet  14  includes solenoid armature  15  and a magnetic core  28 , which is situated coaxially to solenoid armature  15 , a solenoid coil  29  that is slid onto magnetic core  28 , and a pot-type magnet housing  30  that accommodates magnetic core  28  and solenoid coil  29 . Magnet housing  30 , which partially extends over valve body  21 , securely encloses valve cover  22  and incorporates it, as a magnetic yoke, in the magnetic circuit of electromagnet  14 . Solenoid armature  15  extends through a central opening  31  in valve cover  22 . A valve closing spring  32  that is disposed in a central axial bore  33  in magnetic core  28  acts on the end face of solenoid armature  15  facing away from sealing element  16 . The preload of valve closing spring  32  and, therefore, the closing force of valve element  12  is adjusted using an adjusting screw  35  that can be screwed in a threaded section  34  of axial bore  33 . 
         [0021]    In the embodiment shown, bearing element  18  of valve element  12  is designed as a flat spring  36  which is disposed in valve chamber  23  and is secured in valve housing  20  on the edge that extends between valve body  21  and valve cover  22 , and which is securely connected in the center to sealing element  16  and solenoid armature  15 . Sealing element  16  is disposed on the end face of solenoid armature  15  and is pressed into solenoid armature  15  e.g. using a plug  161 , wherein plug  161  is inserted through a central hole  361  in flat spring  36 , thereby fixedly clamping flat spring  36  between sealing element  16  and solenoid armature  15 . Flat spring  36 , which is shown in  FIG. 1  in its clamped position in valve housing  20 , is depicted in  FIG. 2  in a top view together with a plurality of damping bodies  13  installed thereon, wherein damping bodies  13  are shaded to enhance their visibility. 
         [0022]    Damping bodies  13 , which are preferably gel-like, are disposed in valve chamber  23  such that they are offset relative to each other in the circumferential direction. They bear against flat spring  36  on one side and, on the other side, against valve cover  22  which forms one of the walls of valve chamber  23 , whereby they are fastened to valve cover  22 , preferably being bonded thereto. Three such damping bodies  13 , which are offset from each other by 120°, are present in the embodiment shown, as depicted in  FIG. 2 . Advantageously, flat spring  36  is preloaded toward valve seat  17  and contributes to the closing force of valve element  12 . 
         [0023]    To ensure that solenoid armature  15  is contactlessly displaceable in central opening  31  in valve cover  22 , a further bearing element  37  for valve element  12  is provided on the side of solenoid armature  15  facing away from bearing point  18 . Further bearing element  37  is a flat spring  38  which is disposed between solenoid armature  15  and magnetic core  28 , and which bears against the end face of solenoid armature  12  on one side and, on the other side, against the end face of magnetic core  28 . Further flat spring  38  has the same shape as flat spring  36  of bearing element, which is depicted in FIG.  2 , although with a smaller outer diameter. Damping bodies  13  that are placed on flat spring  36 , as shown in  FIG. 2 , are not included, of course. 
         [0024]    It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
         [0025]    While the invention has been illustrated and described as embodied in a device for controlling the flow of a liquid or gaseous medium, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
         [0026]    Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.