Abstract:
An air filtration system for purifying an air stream, such as the intake air for an internal combustion engine, including a system plate ( 10 ), an unfiltered air zone ( 13 ), a filter housing ( 12 ) containing a filter element ( 16 ), and a filtered air zone ( 19 ). The filter element hermetically seals and separates the unfiltered air zone ( 13 ) from the filtered air zone. The unfiltered air zone ( 13 ) is configured by a first half shell ( 11 ), which is connected to the system plate ( 10 ) in a fixed, hermetically sealed manner. The filter housing ( 12 ) is also connected to the system plate in a fixed and sealed manner. The permanent, air-tight connection of the first half shell to the system plate allows the air filtration system to be manufactured in a simpler, more rapid and more cost effective manner by obviating the need for seals and connecting elements, as well as the need to assemble such parts.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of international patent application no. PCT/EP01/03298, filed Mar. 23, 2001, designating the United States of America and published in German as WO 01/96729, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application no. DE 100 28 956.8, filed Jun. 16, 2000. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to an air filtration system comprising a system plate, a filter chamber having an air intake and an air outlet, and a filter element sealingly arranged in the filter chamber between the air intake and the air outlet so that air entering through the intake must pass through the filter element to reach the air outlet, in which the filter element divides an unfiltered air zone from a filtered air zone. 
     An intake module for an internal combustion engine, which comprises a plurality of integrated components, such as an unfiltered air intake opening, an unfiltered air intake passage, an air filter, a filtered air passage, and a filtered air connecting piece, is known from German patent application no. DE 198 02 074. The intake module is dimensioned in such a way that it completely covers the internal combustion engine. For this purpose, a flat plate is provided, which has shaped connection contours on its bottom side. A bottom part is attached to the bottom side of the plate, which is set on the connection contours and connected to the plate using multiple screws. To provide a sealed connection between the plate and the bottom part, a seal is inserted between the plate and the bottom part. However, screwing the top part onto the bottom part, and the insertion of the seal, results in high costs for materials and for assembly. Furthermore, the plate is a very complicated component, which is therefore difficult to manufacture due to the shaped connection contours. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to provide an improved air filtration system for an internal combustion engine. 
     Another object of the invention is to provide an air filtration system which can be produced easily with low expenditures for materials and for assembly. 
     These and other objects are achieved in accordance with the present invention by providing an air filtration system comprising a system plate, a filter chamber having an air intake and an air outlet, and a filter element sealingly arranged in the filter chamber between the air intake and the air outlet so that air entering through the intake must pass through the filter element to reach the air outlet, the filter element dividing an unfiltered air zone from a filtered air zone; the system plate having upper and lower sides and at least partially covering a device; wherein the unfiltered air zone is formed by a first half shell permanently and sealingly attached to the system plate; and the filter chamber is formed by a filter housing attached to the system plate. 
     The air filtration system according to the present invention comprises a system plate having a top side and a bottom side, which at least partially, and preferably completely, covers a device such as an internal combustion engine. Furthermore, the air filtration system includes an unfiltered air intake and an unfiltered air zone, which discharges into a filter chamber. Positioned in the filter chamber is a filter element, which sealingly separates the unfiltered air zone from a filtered air zone having a filtered air outlet. The filter element has a peripheral seal and may be formed, for example, by a filter paper, preferably folded in a zigzag shape, or by a nonwoven filter web. In certain embodiments, the top side of the system plate may be designed as a visually appealing cover plate, and the bottom side of the system plate as function-oriented. 
     The unfiltered air intake discharges into the unfiltered air zone, which is formed by a first half shell in combination with the system plate. The first half shell is connected in a sealed manner to the bottom side of the system plate, thereby defining the unfiltered air zone. In some regions, particularly in the region of the unfiltered air intake, the first half shell may form a closed channel, so that the unfiltered air intake may, for example, be raised above the system plate. The connection of the first half shell to the bottom side of the system plate is a permanent bond which may be produced thermally or chemically, for example, by bonding with an adhesive. In this case, the use of an additional seal is not necessary, since the bond itself forms a seal. The sealing is performed, for example, by the adhesive applied. Mechanical attachment devices and seals thus may be omitted as a result of the permanent bonding of the system plate to the first half shell. 
     The filter chamber is formed by a filter housing which is attached to the system plate. In this case, for example, the filter housing may be a closed filter housing having openings which allow unfiltered air to enter the filter chamber and filtered air to exit. One side of the housing is then rigidly connected to the system plate. The opening in the filter housing for admitting the unfiltered air may be connected either detachably or permanently to the first half shell, which encloses the unfiltered air zone. 
     The filtered air zone is connected on the downstream side of the filter element to the filter chamber. It may be connected, for example, exclusively to the filter housing and not have any contact to the system plate. In this case, the filtered air zone may be designed, for example, as a connecting piece, having any desired cross-section, which extends directly from the filter housing. 
     According to a further embodiment of the present invention, the filtered air zone is formed by a second half shell in combination with the system plate. In this case, the second half shell may be attached to the filter housing or constructed in one piece therewith and may adjoin the opening for the filtered air in the filter housing or correspond to the downstream filter chamber through exclusive contact to the system plate, so that the filtered air flows through an opening in the system plate to the filtered air outlet. In this embodiment, the opening for the filtered air is positioned on the filter housing in such a way that it is located on the side connected to the system plate and covers the passage in the system plate. The second half shell may be positioned on the top side of the system plate, so that the filtered air may be conducted along the top side of the system plate. Through this design, diverse types of air guide variants are possible, which may be constructed in a very tight space. 
     If the second half shell adjoins both the filter housing and the bottom side of the system plate, the opening for the filtered air in the filter housing must be positioned in such a way that it discharges into the second half shell. Various types of air guidance possibilities may thus be constructed, in which both the unfiltered air inlet and the filtered air outlet are arranged on the bottom side of the system plate. 
     It is advantageous to permanently affix the filter housing to the system plate. For this purpose, thermal or chemical bonding methods may be used for the permanent attachment between the filter housing and the system plate. The bond between the system plate and the filter housing may be produced using the same bonding method as the bond between the first half shell and the system plate. Therefore, the first half shell and the filter housing may be bonded to the system plate in one work step, which saves time during assembly of the air filtration system. 
     In one specific embodiment of the present invention, the permanent bond is a weld seam. This weld seam may be produced, for example, using vibration welding methods or ultrasound welding methods. During such welding of the components to one another, material is melted, which forms a weld seam. Tolerances may thus be compensated, so that a sealed joint may be produced rapidly and reliably at a low assembly cost. 
     According to a further embodiment, the filter housing is formed by a housing frame, having a housing cover, and the system plate. The housing frame is welded to the bottom side of the system plate. Consequently, the bottom side of the system plate forms a part of the filter housing. The housing cover is sealingly attached in an air-tight manner to the housing frame, so that no air may escape from the filter housing or enter the filter housing. Sealing means, in particular rubber seals, may be provided for the sealed joint between the housing frame and the housing cover. Furthermore, the housing cover may be removably affixed to the filter frame, so that the filter element disposed in the filter housing may be replaced as necessary. In advantageous embodiments, the filter housing may be snapped removably onto the housing frame, so that the housing cover is rapidly and easily removable from the housing frame. 
     It is advantageous to dispose ribs on the system plate. In order to optimize the connection between the system plate and the first half shell, ribs, which may in particular be designed as narrow, flat ribs, may be provided on the bottom side of the system plate. The ribs may be straight or curved, and in certain embodiments they may follow the contour of the components connected to the system plate. As a result of the formation of the ribs, the system plate is provided with additional material, which may be melted during welding, for example, or which offers an additional contact surface during adhesive bonding. In addition, these ribs also increase the intrinsic stability of the system plate. 
     According to one advantageous embodiment of the present invention, the unfiltered air zone has an acoustically effective, curved air guide. In this case, the first half shell, which encloses the unfiltered air zone, is constructed in such a way that its course forms a curved air guide having desired acoustic effects. Multiple curved air guides, which positively influence the noise generated by the air flowing through the system, may also be provided in order to produce either a reduction in noise or a change in the emitted sound frequency which is generated. An omega curve represents an especially advantageous embodiment of the curved air guide. 
     In a further embodiment of the present invention, the unfiltered air zone has a second unfiltered air inlet, which may be opened using a flap. In this embodiment, the first half shell may be constructed in such a way that it also forms the second unfiltered air inlet. In this case, the flap is positioned in the first half shell in such a way that it may close off either the first unfiltered air inlet or the second unfiltered air inlet as a result of appropriate switch settings. In addition, a switch setting is conceivable in which the flap at least partially enables or opens both unfiltered air inlets. The flap is preferably positioned in the region where the unfiltered air zone which extends from the first unfiltered air inlet meets the unfiltered air zone which extends from the second unfiltered air inlet. In other embodiments, two separate flaps may also be provided, a first flap for closing off the first unfiltered air inlet and a second flap being used to close the second unfiltered air inlet. The two flaps advantageously have a connection which controls the flaps in mutual dependence on one another. By using a second unfiltered air inlet which may be opened, air may be drawn in from different surroundings. This is particularly advantageous in motor vehicles, since if the first unfiltered air inlet comes into contact with water or snow, for example, the flap may seal this unfiltered air inlet and open the second unfiltered air inlet, so that, for example, warmed air may be drawn in from the motor compartment, and the internal combustion engine may operate without danger. 
     A further embodiment provides attachment points for mounting the air filtration system on an adjacent internal combustion engine. The attachment points may be positioned on the system plate or on the components connected to the system plate. The attachment points may be formed directly on the system plate or on the components, or they may be constructed as separate components, particularly components made of rubber. Multiple attachment points are preferably provided distributed over the air filtration system. If the attachment points are constructed as separate components, in addition to the attachment function, they may also serve as oscillation dampers or as spacers between the internal combustion engine and the air filtration system, so that the air filtration system is not subjected to excessive mechanical or thermal loads. 
     In one advantageous embodiment of the present invention, the half shells and the system plate are made of a thermoplastic synthetic resin material. Therefore, the individual components of the air filtration systems may be produced easily and rapidly using injection molding, and the components may be assembled, for example, using friction welding. In addition, the air filtration system may be easily disposed of or recycled after use. 
     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 constructed 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 
     The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings in which: 
     FIG. 1 shows an air filtration system according to the invention; 
     FIG. 2 shows a sectional view of the air filtration system taken along section line A—A of FIG. 1; 
     FIG. 3 shows another air filtration system embodiment according to the invention; 
     FIG. 4 is a sectional view of the air filtration system of FIG. 3 taken along section line B—B. 
     FIG. 5 is another sectional view of the air filtration system of FIG. 3 taken along section line C—C; and 
     FIG. 6 is yet another sectional view of the system of FIG. 3 taken along section line D—D. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An air filtration system is shown in a top view in FIG.  1 . The air filtration system comprises a system plate  10 , which is permanently affixed to a first half shell  11  and a filter housing  12 . First half shell  11  encloses an unfiltered air zone  13  in combination with system plate  10 . Unfiltered air zone  13  has an unfiltered air intake  14  and is connected to filter housing  12 . 
     As shown in FIG. 2, filter housing  12  encloses a filter chamber  15 , which is divided into an unfiltered air zone  17  and a filtered air zone  18  by a filter element  16 . Filter element  16  is inserted into filter housing  12  to form a seal. In this illustrative embodiment, a filtered air zone  19  having a filtered air outlet  20  adjoins filtered air zone  18 . Filtered air zone  19  is formed by a connection piece  21 , which is rigidly connected to filter housing  12 . In order that filter element  16  may be replaced as necessary, filter housing  12  is constructed in two pieces, the two housing parts being releasably connected using screws  22 . 
     The air filtration system draws air from its surroundings. This air flows through unfiltered air intake  14  into unfiltered air zone  13 . The air flows into unfiltered air zone  17  (shown in FIG. 2) of filter chamber  15  through a first opening  23  (shown in FIG. 2) in filter housing  12 , which is completely covered by unfiltered air zone  13 . In order for the air to reach filtered air zone  18  (shown in FIG.  2 ), it must flow through filter element  16 , where it is filtered. From filtered air zone  18 , the air flows to filtered air zone  19  and exits the air filtration system through filtered air outlet  20 . 
     FIG. 2 is a sectional view of the air filtration system of FIG. 1 taken along section line A—A. The components corresponding to FIG. 1 are identified by the same reference numbers. First half shell  11  is sealingly welded in an air-tight manner to system plate  10  to form unfiltered air zone  13 . Filter housing  12  comprises a bottom part  24  and a housing cover  25 . Housing cover  25  is removably attached to bottom part  24  using screws  22 . 
     Bottom part  24  has a housing floor  26 , which is permanently affixed to system plate  10 . Furthermore, bottom part  24  encloses unfiltered air zone  17 . A first opening  23 , which is enclosed by first half shell  11  with system plate  10 , is provided in bottom part  24 . The air may flow from unfiltered air zone  13  into unfiltered air zone  17  through this first opening  23 . 
     Filter housing  12  also has a second opening  27 , which is positioned in housing cover  25 . The filtered air from filtered air zone  18 , which is formed by housing cover  25 , may then flow through this second opening  27  into filtered air zone  19 , formed by connection piece  21 . Filter element  16  has a rectangular configuration and is positioned in the filter housing parallel to system plate  10  such that it forms a seal which separates unfiltered air zone  17  from filtered air zone  18 . 
     A variant air filtration system embodiment is illustrated in FIG.  3 . The air filtration system comprises a system plate  10  made of synthetic resin material, which has a visually appealing top side  28  and a function-oriented bottom side  29 . For clarity of illustration, in the following figures system plate  10  is shown inverted so that the “top” side in normal use is toward the bottom of the page, and the “bottom” side in normal use is shown on top. System plate  10  is slightly curved and has angled edges. Top side  28  of the system plate may be constructed, for example, in the form of a polished or textured surface to which symbols, such as a company logo, may be applied. Bottom side  29  has ribs  30 , which may be used both for stability and to assist attachment of components arranged on system plate  10 . Ribs  30  may run in a straight line as shown, or in other embodiments they may, for example, follow the contour of first half shell  11  or filter housing  12 . Furthermore, system plate  10  has an opening  31 , through which, for example, attachment components may project or maintenance work may be performed on an internal combustion engine positioned beneath it. 
     A first half shell  11  is affixed in an air-tight manner to bottom side  29  of system plate  10  using the vibration welding method so that an unfiltered air zone  13  is formed. First half shell  11  completely encloses an unfiltered air intake  14 , so that unfiltered air intake  14  may also be positioned at a distance from system plate  10 . Unfiltered air zone  13  has an omega curve  33  in one section, through which the air guidance is influenced and an acoustic effect is achieved. An attachment nipple  32  is provided on unfiltered air zone  13 , to which, for example, a crankcase ventilation line (not shown) may be attached. In this illustrative embodiment, first half shell  11  is configured in such a way that it includes a second unfiltered air intake  34 . Second unfiltered air intake  34  also discharges into unfiltered air zone  13 . A flap  35  is provided to block or unblock unfiltered air intakes  14  and/or  34 . For this purpose, flap  35  is positioned in a T-shaped region of unfiltered air zone  13 . In a first end position, the flap closes off second unfiltered air intake  34  from a subsequent filter housing  12 . In a second end position (shown in broken lines), flap  35  blocks first unfiltered air intake  14  from subsequent filter housing  12 . Therefore, flap  35  may be used to control aspiration of air from different regions. 
     Unfiltered air zone  13  discharges into a filter chamber  15  formed by filter housing  12 . A filter element  16  (not shown) is positioned in filter chamber  15 . Filter housing  12  comprises a housing cover  25  and a bottom part  24 . Housing cover  25  is secured to bottom part  24  by snap connections  36 . Unfiltered air zone  13  may be connected to filter housing  12  by a detachable connection to housing cover  25  or by a permanent connection to bottom part  24 . Bottom part  24  is sealingly welded in an air-tight manner to system plate  10 . A second half shell  37 , which encloses a filtered air zone  19 , adjoins filter chamber  15  on the filtered air side. Attachments nipples  32  are provided on second half shell  37 , through which, for example, crankcase ventilation gases may be introduced into the air filtration system. Second half shell  37  includes a connecting piece  21 , which is constructed as a separate component. Connecting piece  21  surrounds a filtered air outlet  20 , which does not touch system plate  10 . In this illustrative embodiment, bottom part  24  of filter housing  12  is constructed in one piece with the second half shell  37 , so that the number of parts is reduced. 
     FIG. 4 shows a sectional view of the air filtration system of FIG. 3 taken along section line B—B. The components corresponding to FIG. 3 are identified by the same reference numbers. First half shell  11  is sealingly welded in an air-tight manner to system plate  10 , so that unfiltered air zone  13  is enclosed. Weld seams  38 , which join system plate  10  to first half shell  11 , may be produced, for example, through friction welding or ultrasound welding. In order that, for example, first half shell  11  may be positioned exactly on system plate  10 , bottom side  29  of system plate  10  may have depressions (not shown), which allow first half shell  11 , for example, to be plugged in. In this way, the welding process may be simplified. 
     FIG. 5 shows a sectional view of the air filtration system of FIGS. 3 and 4 taken along section line C—C. The components corresponding to FIG. 3 are identified by the same reference numbers. Second half shell  37  is sealingly welded in an air-tight manner to system plate  10 , so that filtered air zone  19  is formed. From filtered air zone  19 , the filtered air enters connecting piece  21 , which is sealingly bonded to second half shell  37 . In other embodiments, connecting piece  21  may also be constructed in one piece with second half shell  37 . The filtered air may exit the air filtration system through filtered air outlet  20  and, for example, enter the intake manifold of an internal combustion engine (not shown). 
     A sectional view of the air filtration system taken along section line D—D of FIG. 3 is illustrated in FIG.  6 . The components corresponding to FIGS. 3 through 5 are identified by the same reference numbers. A filter element  16 , which is inserted between housing cover  25  and bottom part  24  to form a seal, is installed in filter chamber  15 . Bottom part  24  is designed as a frame and has no floor. Therefore, filtered air zone  18  has direct contact to system plate  10 . Housing cover  25  has a first opening  23 , through which the air to be filtered may enter unfiltered air zone  17 . First opening  23  is enclosed by first half shell  11  outside of filter housing  12 . 
     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 falling within the scope of the appended claims and equivalents thereof.