Abstract:
A device according to the related art for determining at least one parameter of a medium flowing in a line is unable to prevent pollutants from getting out of the line into the atmosphere. The device of the present invention has a filter which is able to take up the pollutants and thus prevent them from getting into the atmosphere.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed toward a device for determining at least one parameter of a medium flowing in a line, and the use of an activated carbon canister in a device for determining at least one parameter of a medium flowing in a line.  
         BACKGROUND INFORMATION  
         [0002]    Known devices for determining at least one parameter of a medium flowing in a line have an air filter upstream in the line, the air filter filtering out only liquid and solid particles, however. Pollutants for the atmosphere in the form of gaseous emissions such as hydrocarbon vapors from an induction tract of internal combustion engines which get into the line cannot be absorbed by the air filter.  
         SUMMARY OF THE INVENTION  
         [0003]    The device of the present invention for determining at least one parameter of a medium flowing in a line and the use according to the invention of an activated carbon canister in a device for determining at least one parameter of a medium flowing in a line have the advantage that in a simple manner pollutants are prevented from escaping from the line into the atmosphere.  
           [0004]    Various advantageous variants exist for arranging a filter in the line. First of all, the filter having a specific axial length may be disposed on an inner wall of the line, and may be tubular. However, the filter does not necessarily have to be disposed about the entire periphery of the line, but rather may also be arranged only in sections in the circumferential direction. The ability of a filter to absorb pollutants such as hydrocarbon vapors is a function, inter alia, of its surface, past which the medium flows. Thus, it is possible to decide which variant is practical depending on the application case.  
           [0005]    In order not to reduce in size the cross-section of the line in which the medium flows compared to the device without a filter, a depression in which the filter is disposed is advantageously formed in a wall of the line.  
           [0006]    The filter may advantageously also be formed as a bar which, for example, has the length of a diameter of the line.  
           [0007]    An activated carbon canister or a nonwoven fabric have proven to be advantageous filters. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 a  shows a first exemplary embodiment of a device constructed according to the present invention.  
         [0009]    [0009]FIG. 1 b  shows a section in the radial direction along line B-B in FIG. 1 a.    
         [0010]    [0010]FIG. 1 c  shows a second exemplary embodiment of a device constructed according to the present invention.  
         [0011]    [0011]FIG. 1 d  shows a section in the radial direction along line D-D in FIG. 1 c.    
         [0012]    [0012]FIGS. 2 a  and  2   b  show a second exemplary embodiment of a device constructed according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]    [0013]FIG. 1 a  shows how a device  1  of the present invention, having a line  3  in which the medium flows, is constructed by way of example. Part of device  1  for determining at least one parameter of the flowing medium is a housing  6  which is inserted, for example, in a plug-in manner through an insertion opening  12  into a wall  9  of line  3 . Wall  9  delimits a flow cross-section of line  3 . For example, in device  1 , a measuring element  15 , arranged in housing  6 , is used which determines, for instance, the volumetric flow of the flowing medium as a parameter. Additional parameters which may be measured are, for example, the pressure, the temperature, a concentration of a medium component or a flow velocity, which are determined using suitable sensors. Housing  6  has in the axial direction a longitudinal axis  18  which, for example, in the mounting direction of housing  6 , runs into line  3 . The direction of the flowing medium, in the following known as the main flow direction, is indicated in the drawing by corresponding arrows  21 , and runs there from left to right. Housing  6  includes a bypass channel (not shown), which, for example, upstream on housing  6  has an entrance aperture  24 . The medium flows through entrance aperture  24  into the bypass channel, and there flows past measuring element  15 .  
         [0014]    Upstream of housing  6 , provided in line  3  is, for example, at least one element  25  for influencing the flow. Element  25  is, for example, a flow straightener and/or an element which reroutes liquid or solid particles flowing in the medium in such a way that they do not get into entrance aperture  24  of housing  6 .  
         [0015]    A filter  30  is disposed, for instance, on an inner wall  28  of line  3  and extends in axial direction  21 , for example, upstream and downstream of housing  6 . Any other disposition of filter  30  with respect to housing  6  is possible. For example, if line  3  has a circular cross-section, filter  30  is configured, for instance, in the shape of a circle segment and is secured to inner wall  28  of line  3 . If the cross-section of line  3  is not to be reduced in size by the filter, then configured in wall  9  of line  3  is at least one depression  33  which accommodates filter  30  so that the cross-section of line  3  upstream and downstream of filter  30  is not altered compared to the device without filter  30 .  
         [0016]    For example, nonwoven fabric, an activated carbon canister or other known filter types are available as filter materials. Depending on the known emissions, the filter may have the substances which are known to be chemisorptive for them and which filter out the emissions from the line by chemisorption.  
         [0017]    During the operation of an internal combustion engine of a motor vehicle, hydrocarbon vapors of a fuel, for instance, may get into an induction tract, line  3  being a part of this induction tract. When the internal combustion engine is in operation, the vaporized hydrocarbons are carried along by the flowing medium into the internal combustion engine and are burned there, so that no harmful emissions are able to develop. However, when the internal combustion engine is shut down, gaseous emissions upstream may get through line  3  into the atmosphere. Filter  30  is provided to prevent this. The gaseous emissions are taken up by filter  30 , e.g. are adsorbed or absorbed. During the operation of the internal combustion engine, depending upon the type of filter, for instance, when working with an activated carbon canister, the emissions taken up by filter  30  are released again to the medium flowing past and are burned in the internal combustion engine, so that filter  30  is again completely or at least partially cleaned.  
         [0018]    [0018]FIG. 1 b  shows a section in the radial direction along line B-B in FIG. 1 a . For simplification, housing  6  and element  25  were not shown here. Two filters  30  are disposed in two depressions  33 , the diameter of line  3  not having been reduced in so doing, that is to say, line  3  has no shoulder at this location. Depression  33  and the filter are configured in cross-section with an annular segment shape.  
         [0019]    [0019]FIG. 1 c  shows a further exemplary embodiment of device  1  according to the present invention. In comparison to FIG. 1 a , filter  30  is tubular, e.g. annular, and is arranged along a circumferential line of line  3 . In the same way, depression  33  in the circumferential direction of line  3  is annular. FIG. 1 d  shows this in a section in the radial direction along line D-D in FIG. 1 c.    
         [0020]    [0020]FIG. 2 a  shows a second exemplary embodiment of device  1  according to the present invention. In this example, filter  30  is arranged as a bar, e.g. rectangular plate, in line  3 . In the radial direction, the bar has, for example, the length of the diameter of line  3 . In this case, filter  30 , constructed as a bar, may take any position in line  3 , and may also have shapes deviating from a plate, such as tubular or oval, and may, for instance, also be situated only in the center of line  3 .  
         [0021]    [0021]FIG. 2 b  shows a view of device  1  of FIG. 2 a  according to the invention contrary to main flow direction  21 . For example, filter  30  is positioned downstream of housing  6 . It may also just as well be disposed upstream of housing  6 . It is equally possible to secure filter  30  on housing  6 , so that with the insertion of housing  6  into wall  9  of line  3 , filter  30  is installed and is possibly exchangeable, as indicated in FIG. 2 a  with a dotted line on the downstream part of housing  6 .