Abstract:
An intake filter for an internal combustion engine for a motor vehicle including an unfiltered air intake region, a filter medium and a filtered air conduit, in which the unfiltered air intake region is arranged beneath the engine hood of the motor vehicle and is attached to the engine hood. The filter medium is tubular body which has a porosity that ensures a sufficient filtration of the intake air for the internal combustion engine.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of international patent application no. PCT/EP2005/051486, filed Mar. 31, 2005 designating the United States of America and published in German on Oct. 13, 2005 as WO 2005/095783, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application no. DE 10 2004 016546.7, filed Mar. 31, 2004.  
       BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to an intake filter for an internal combustion engine of a vehicle comprising a dirty air intake area, a filter medium and a clean air pipe, wherein the dirty air intake area is disposed on the underside of the engine hood of the vehicle and is connected thereto.  
         [0003]     U.S. Pat. No. 4,932,490 discloses a vehicle with an internal combustion engine. To supply the intake air for the internal combustion engine, an unfiltered air passage is provided on the engine hood to receive the air flowing in from the front of the vehicle. This unfiltered air passage leads to a filter housing in which is disposed a filter element for filtering the dirty air. The clean, filtered air flows through a filtered air passage disposed on the engine hood side to a transfer unit from where it is guided to the internal combustion engine through a flexible hose. When the engine hood is opened, the flexible hose is separated from the clean air passage. The air filter is mounted to the engine hood and can be replaced as needed. To mount the air filter, a corresponding housing is provided, which can be opened.  
         [0004]     One drawback of this device is that the housing of the air filter is a rigid structure. Similarly, the unfiltered air- and filtered air-carrying members are specially configured sheet metal parts that are mounted to the engine hood. They cause a stiffening of the engine hood in an area that should be relatively flexible for safety reasons. In addition, a special housing is required for the air filter element, which adds a not inconsiderable amount of weight to the engine hood.  
       SUMMARY OF THE INVENTION  
       [0005]     Accordingly, it is an object of the invention to provide an improved internal combustion engine air filter which is mounted to the engine hood.  
         [0006]     Another object of the invention is to provide a hood-mounted intake filter for an internal combustion engine which does not impair the function of the engine hood or require a special housing.  
         [0007]     These and other objects are achieved in accordance with the present invention by providing an intake filter for an internal combustion engine of a motor vehicle comprising an unfiltered air intake area, a filter medium, and a filtered air duct, in which the unfiltered air intake area is disposed on the underside of the engine hood of the vehicle and is attached to the engine hood; and in which the filter medium comprises a tubular body having a porosity such that adequate filtering of the intake air for the internal combustion engine is ensured.  
         [0008]     Thus, in accordance with the present invention, the filter medium is formed of a tubular body that has a porosity sufficient to ensure adequate filtering of the intake air for the internal combustion engine.  
         [0009]     The present invention is advantageous in that the filter system can be accommodated within the engine compartment of a vehicle in a space-saving manner. In particular, the engine hood of the vehicle and the space between the engine hood and the engine can advantageously be used to mount the relatively soft element or elements of a tubular filter body. Due to the relatively large size of the area available, a plurality of tubular elements may be arranged in parallel. The configuration can be adapted to the engine hood structure.  
         [0010]     In one embodiment of the invention the proposed tubular body comprises a tubular filter having a diameter ranging from 40 to 80 mm. A tubular filter of this type can be formed of, for example, a nonwoven body, the nonwoven material of which has filtering properties.  
         [0011]     It is of course also possible, according to a further embodiment of the invention, to provide the tubular body with a pleated geometry to facilitate a curved installation. The filter element is pleated, for example, by forming a plurality of parallel folds arranged side by side, which extend perpendicularly to the longitudinal axis of the filter.  
         [0012]     In accordance with another embodiment of the invention the filter medium is provided on the filtered air side with a resilient support member. This support member may, in particular, comprise a helically extending support wire or a correspondingly configured support grid. Of course, a support member can also be formed of polymeric material as well as of metal.  
         [0013]     To prevent the intake of hot engine exhaust, in one advantageous embodiment of the invention, the tubular body may be provided with a cover. This cover ensures that the fresh air to be drawn in flows in at defined points, as for example in the upper area of the radiator grille, and is supplied to the intake filter. The cover also may have acoustic properties, so that it helps reduce the intake noise of the internal combustion engine.  
         [0014]     According to another embodiment, the tubular body is a wound filter element which comprises a plurality of groove-like hollow channels with adjacent channels open and closed at alternate ends. Wound filters of this type have the advantage that they have a very short overall length and a large effective filter surface. They are also compact and easy to replace.  
         [0015]     These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawing figures, in which:  
         [0017]      FIG. 1  is a schematic view of the engine compartment of an automobile with hood open;  
         [0018]      FIG. 2  shows the construction depicted in  FIG. 1  with a modified filter variant;  
         [0019]      FIG. 3  is a perspective view of a wound filter element for installation in an engine hood;  
         [0020]      FIG. 4  is perspective view of a variant of a wound filter element for optimal adaptation to the structure of an engine hood;  
         [0021]      FIG. 5  is a schematic representation of an engine compartment of a motor vehicle;  
         [0022]      FIG. 6  is perspective representation of a pleated filter element, and  FIG. 7  is a front elevational detail view of the device illustrated in  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0023]      FIG. 1  schematically illustrates the engine  10  of a motor vehicle. On this engine  10 , there is an opening  11  through which the intake air flows in and from where it is distributed to the individual cylinders of the engine. An engine hood  13  is arranged on top of the engine compartment  12 . In  FIG. 1  the engine hood is shown open so that the underside of the hood is visible. On the underside of hood  13  there is a plenum chamber  14  with a filtered air opening  15 . This plenum chamber in turn has openings to the outside, which communicate with tubular filter elements (tubular filters  16 ,  17 ,  18 ,  19 ,  20 ). These tubular filters each have a round or oval cross section and are likewise depicted only schematically. In addition to the tubular filters, resonance chambers  21  and  22  are provided, which communicate with the plenum chamber  14  through openings and which are appropriately configured to dampen the intake air noise. The tubular filters and the resonance chambers are covered relative to the engine by a substantially airtight cover  23 . In the drawing the cover is merely indicated by a broken line. This cover is open toward the front of the vehicle and toward the front of the engine hood, so that fresh air can flow into the filter area from the front, i.e., from the front of the vehicle, as indicated by arrows  24 . This fresh air is cleaned by the tubular filters and made available to the internal combustion engine.  
         [0024]     A connection between the clean air opening  15  and the opening  11  for the intake air on the engine  10  is established by closing the engine hood. If desired, both openings may be permanently connected by a flexible connecting hose  25 . It is also possible to use suitable interengaging connecting members to produce the elastic connection, which is released when the engine hood is opened, but this requires that the opening  11  be closed when the engine hood is open. Closure of opening  11  can be accomplished, for example, by a suitable diaphragm or flap over the opening.  
         [0025]      FIG. 2  shows an alternate embodiment using a flexible tubular filter  26  connected to the intake plenum  14  in place of the static tubular filters. In this figure, components corresponding to those depicted in  FIG. 1  are identified by the same reference numerals. The tubular filter  26  is formed of a nonwoven web or paper material with filtering properties. The filter medium itself has a plurality of parallel pleats arranged side by side and extending perpendicularly to the longitudinal axis of the filter. This makes possible a flexible installation of the filter medium adaptable to the structure of the engine hood. Of course, many different types of installation are feasible here. For high volume engines, in particular, it is possible to provide a correspondingly large active filtering surface.  
         [0026]     Figure shows the filter medium as a wound filter element. This wound filter consists of a first, flat filter web  27  onto which is placed a second, corrugated web  28 . Corrugated web  28  is glued to the flat web  27  by a bead of adhesive  29  on one side of the filter element. During winding, a bead of adhesive  30  is applied to the opposite side to join the corrugated web  28  to the previously wound flat web  27 . This creates channels  31  which are open at one end so that air can enter. The air cannot escape on the opposite end, however, because the opposite end is closed by the adhesive. Instead, the air must pass through the corrugated filtering web, whereby it is filtered, into an adjacent channel which is open at the opposite end so that the now filtered air can exit from the opposite side. A wound filter of this type can, of course, also have an oval shape. Alternatively, the flat and corrugated layers can be stacked to form a cube as shown in  FIG. 4 .  
         [0027]      FIG. 4  also illustrates the alternately closed openings of the individual channels. The unfiltered air enters the channels in the direction indicated by arrows  32 , flows through walls of filter material separating adjacent channels as indicated by arrows  33 , and leaves the filter element clean as indicated by arrows  34 .  
         [0028]      FIG. 5  is a schematic view of the front end of a vehicle, including the internal combustion engine  40 , which is mounted above a floor panel  41 . A cooling system  42  is provided in front of the internal combustion engine. A bumper  43  is located in front of the cooling system  42 . The engine compartment is closed by the engine hood  44 . A plenum chamber  45  is mounted to the underside of the engine hood. An intake manifold  47  extends from this plenum chamber  45  through a connecting flange  46  to the internal combustion engine  40 . At least one intake air duct  48  is associated with the plenum chamber  45 . Each intake air passage  48  is likewise disposed directly on the underside of the engine hood  44  and extends to the air inlet  49 . Air inlet  49  is disposed in the area of the front end of the internal combustion engine. A tubular filter  50  is disposed inside intake air passage  48  and extends from the air inlet  49  over a specific length of the intake air passage.  
         [0029]     To reduce intake noise at the air inlet  49 , a flap valve  51  may be provided in the intake air passage  48 . This reduces the cross-section of the passage depending on the required air volume and thereby prevents sound radiation of the intake noise of the internal combustion engine. It is also possible to dispose this flap valve directly at the air inlet  49 , optionally in front of the tubular filter  50 . Below the intake air passage  48 , a sound absorbing insulating mat  52  is provided, which simultaneously acts as the lining for a plurality of intake air passages. If the engine hood  44  can be opened, the intake manifold  47  is a pipe that is flexible over its length. This flexibility is obtained, for example, by pleating or by a telescopic construction. If the engine hood can be removed only for maintenance purposes, the intake manifold  47  can be made rigid. In this case, the intake manifold  47  must be detached at the connecting flange  46 . In these cases, the connection between intake manifold  47  and connecting flange  46  can be a plug-in connection.  
         [0030]      FIG. 6  is a detail view of a tubular filter  50  which is pleated in longitudinal direction and disposed in a closed intake air passage  48 . Unfiltered air flows into the interior of the tubular filter  50 . This of course requires the hatched area  52  to be sealed, which is accomplished by a correspondingly configured flange. The air to be cleaned flows outwardly within the intake air passage  48  into the clean air area and then flows through the intake air passage to the plenum chamber  45 .  
         [0031]      FIG. 7  is a front elevational detail view of a vehicle with the individual intake air passages  48   a - d  disposed in the area of the air inlet. It may be seen here that four individual intake air passages run to the plenum chamber. The advantage of individual intake air passages is that they can take different paths and can also detour around structures of the engine hood if necessary. At the entry of the intake air passages into the plenum chamber, the cross section abruptly changes. This abrupt change in cross section is necessary to improve the intake acoustics, i.e., to reflect sound waves. If the intake air passages are disposed on the underside of the engine hood it is advantageous to seal the openings relative to the engine compartment so that no hot air is drawn in, but fresh air from the area of the front end can be supplied in any case.  
         [0032]     The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations within the scope of the appended claims and equivalents thereof.