Abstract:
A valve according to the related art has a filter that has a small physical size.  
     A valve ( 1 ) according to the invention has a filter ( 18 ) integrated in the housing ( 3, 5 ), which said filter is located in the vicinity of an intake-valve opening ( 9 ), by way of which a smaller physical size and a larger opening cross-section for an influent regeneration gas to the convergent-divergent nozzle results.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention is based on a valve with a filter according to the general class of claim 1.  
           [0002]    A magnet valve is made known in DE 199 01 090 A1 that has a dirt-trapping device. This dirt-trapping device is situated concentrically around an armature plate of the valve and therefore increases the radial physical size. Additionally, an opening cross-section for influent regeneration gas is restricted toward the convergent-divergent nozzle.  
           [0003]    The publication DE 195 16 545 A1 shows a valve for the metered introduction of volatilized fuel, in the case of which a filter is installed as a separate component in the vicinity of the intake. The filter must be sealed off from a housing wall and a magnet core.  
         ADVANTAGES OF THE INVENTION  
         [0004]    In contrast, the valve according to the invention having the characterizing features of claim 1 has the advantage that a filter that reduces the radial physical size is situated in the valve in simple fashion. A larger opening cross-section for influent regeneration gas toward the convergent-divergent nozzle also means there is less of a pressure drop in the filter.  
           [0005]    Advantageous further developments and improvements of the valve named in claim 1 are made possible by the measures described in the dependent claims.  
           [0006]    By locating the filter on the base of the housing, a smaller radial physical size is obtained in advantageous fashion.  
           [0007]    The filter is advantageously designed in the shape of a labyrinth. The filter is thereby composed of ribs that are always arranged in such a fashion that a slit is formed between them having a maximum distance between them, at least in parts, by way of which foreign particles get stuck in said slit. 
       
    
    
     SUMMARY OF THE DRAWINGS  
       [0008]    Exemplary embodiments of the invention are presented in the drawings in simplified form and they are explained in greater detail in the subsequent description.  
         [0009]    [0009]FIG. 1 shows a valve according to the invention,  
         [0010]    [0010]FIG. 2 a  shows a housing part with a filter of a valve designed according to the invention.  
         [0011]    [0011]FIGS. 2 b  and  2   c  show a subsection of a housing part with different filters. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    A tank ventilation valve shown in a longitudinal sectional view in FIG. 1 as an exemplary embodiment of any type of valve, e.g., a magnet valve, is used for the metered addition of volatilized fuel from a fuel tank of a (not shown) mixture-compressed internal combustion engine with externally-supplied ignition into the internal combustion engine, e.g., into an intake manifold or, in the case of gasoline direct injection, directly into a cylinder of the internal combustion engine, and it is part of a not further shown evaporative-emissions control system of an internal combustion engine. The design and function of evaporative-emissions controls systems of this type are described in the “Bosch-Technische Unterrichtung Motormanagement Motronic”, Ed. 2, August 1993, pages 48 and 49, for example. A tank ventilation valve and its function are also described, for example, in DE 199 01 090 A1, which is expressly intended to be part of this disclosure.  
         [0013]    The tank ventilation valve  1  has a plurality of housing parts, e.g., a double-component housing with a first housing part  3  that is designed in the shape of a cup, for example, and a housing part  5  that seals said first housing part and is designed in the shape of a cap, for example. The housing part  3  has an intake  7  for connection to a vent connection of the fuel tank, or to a tank for the volatilized fuel filled with activated carbon installed downstream from said fuel tank. The intake  7  has an intake opening  9  located in the region of a base  55  of the housing part  3 .  
         [0014]    The housing part  5  has an outlet  12  for connection, e.g., to the intake manifold of the internal combustion engine. Both the intake  7  and the outlet  12  are mounted on the housing parts  3  or  5 , respectively, along an axial direction  60 , for example.  
         [0015]    An electromagnet  23  is located inside the cup-shaped housing part  3 . The electromagnet  23  has a magnet housing  26  designed in the shape of a cup, for example, with a cylindrical magnet core  35  that is situated coaxial to the valve axis and penetrates the base of the cup, and with a cylindrical field coil  29  seated on a coil holder  32  that surrounds the magnet core  35  in the magnet housing  26 . Located on its side facing the outlet  12  is an armature plate  41  that can be moved against the return force of a return spring  38 , which said armature plate is attracted by the electric magnet  23  and forms a valve device that comes to bear against a seal seat located directly or indirectly against the housing part  5 . The outlet  12  has a flow element  44  in the form of a convergent-divergent nozzle. It is understood, however, that the flow element  44  is not limited to a convergent-divergent nozzle and can also be developed as an orifice or a constriction. The flow element  44  is designed so that the surface of its narrowest flow cross-section is smaller than the surface of the opening cross-section of the seal seat  103 . Furthermore, a diaphragm  46  is located on the armature plate  41 .  
         [0016]    The housing  3 ,  5  has a connector  49 , for example, that is integral with the housing  3 ,  5  and has electrical end fittings  52  for connection to external plug contacts.  
         [0017]    A filter  18  is located on the base  55  of the housing part  3  in the vicinity of the intake opening  9 . The medium that can contain particles from the carbon filter, for example, flows through the intake opening  9  and through the filter  18 —which retains these particles—past the magnet housing  26  in the direction toward the seal seat and, when the armature plate  41  is lifted, to the outlet  12 .  
         [0018]    [0018]FIG. 2 a  shows the first housing part  3  of the valve  1  designed according to the invention with the filter  18 . The filter  18  is located in the vicinity of the intake opening  9 . The first housing part  3  has the base  55 , which is bordered outwardly in a radial direction  63  by a housing wall  57  of the housing part  3 . The base  55  is bordered toward the center by the intake opening  9 . The filter  18  is located on the base  55 , for example. Likewise, the filter  18  is produced integral with the housing  3 , i.e., it is produced during manufacture of the housing  3 , for example.  
         [0019]    The magnet housing  26  is located, e.g., at least partially on the filter  18 . The filter  18  is designed in the shape of a labyrinth, for example.  
         [0020]    [0020]FIG. 2 b  shows an enlarged representation of a circle labelled “B” in FIG. 2 a.    
         [0021]    The filter  18  has at least one channel  65  and at least one slit  68  through which the medium flows, whereby dirt particles stick to the slits  68 , as desired.  
         [0022]    The filter  18  is composed of at least two, e.g., pad-shaped, oval, round, or similarly-shaped ribs  71  that extend in the axial direction  60  and that are arranged in such a fashion that they form the slit  68 . The slit  68  has a width of approximately 0.2 millimeters, for example, so that particles larger than 0.2 millimeters in size stick to the slit  68 . The width of the slit determines a minimum retention size of foreign particles.  
         [0023]    The ribs  71  are arranged as follows, for example. At least two outer ribs  73  extend from the housing wall  57 , starting at or in the vicinity of the housing wall  57 , concentrically situated, in the radial direction  63  toward an intake opening  9 . They have a certain height h in the axial direction  60 , and a width b at a right angle to said height. The outer rib  73  extends radially up to a length I and, therefore, partially to the intake opening  9  on the housing base  55 . The outer ribs  73  are located equidistant from each other in the circumferential direction on the entire circumference or nearly the entire circumference of the housing wall  57 .  
         [0024]    A channel  65  is formed between two directly adjacent, outer ribs  73 .  
         [0025]    Inner ribs  75  are situated radially offset in relation to the outer ribs  73 , which said inner ribs can project partially into the channel  65  of the outer ribs  73 . The shape of the inner ribs  75  is similar to that of the outer ribs  73  and they are also situated concentric around the intake opening  9  in the circumferential direction. The inner ribs  75  are located at a distance from the housing wall  57  and can extend to the intake opening  9 .  
         [0026]    The channel  65  is also formed between the directly adjacent, inner ribs  75 .  
         [0027]    The slit  68  extending in the radial direction  60  is formed between two outer ribs  73  and an inner rib  75 , which said slit has a maximum distance in one location at the most. The slit  68  is therefore smaller or equal to the maximum distance in every other location, by way of which a lower limit is specified for a particle size that is retained at the least.  
         [0028]    The medium flows out of the intake opening  9  through at least one channel  65  of the inner ribs  75  through a slit  68  into a channel  65  of the outer ribs  73 . The foreign particles are retained in the slit  68 . The ribs  73 ,  75  have the same height h in the axial direction. Only one part of the ribs  73 ,  75 , at least three have a height that is greater than h by the maximum distance of, e.g., 0.2 mm or the slit width, so that the magnet housing  26  rests on these higher ribs  73 ,  75 .  
         [0029]    The filter  18  can also be designed in such a fashion that it is composed of pin-shaped ribs  71  that are located in uniform or non-uniform fashion on the base  55  and have a maximum distance between each other of, e.g., 0.2 mm. On the other hand, in place of the inner and outer ribs, the filter  18  can also be formed only by a row of ribs  71  situated side-by-side in the circumferential direction of the housing wall  57 , which said ribs are separated from each other by a maximum distance of 0.2 mm, for example.  
         [0030]    [0030]FIG. 2 c  shows a further exemplary embodiment of the filter  18 . The ribs  71 ,  73 ,  75  are bent in comparison with FIG. 2b, e.g., they are shaped like an “S”. Two directly adjacent ribs  73 ,  75  thereby form a channel  65  through which the medium flows from the intake opening  9  in order to move through the slit  68  in the direction toward the housing wall  57 . From there, it flows along the housing wall  57  in the direction toward the outlet  12 . The outer ribs  73  also form a slit  68  with the housing wall  57 , for example.