Patent Publication Number: US-9416757-B2

Title: Air filter arrangement and connecting duct

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a 35 U.S.C. §§371 national phase conversion of PCT/SE2013/050162, filed Feb. 25, 2013, which claims priority of Swedish Patent Application No. 1250193-8, filed Mar. 1, 2012, the contents of which are incorporated by reference herein. The PCT International Application was published in the English language. 
     TECHNICAL FIELD 
     The invention relates to an air filter arrangement comprising a filter housing for connection to a duct for air to a combustion engine. The invention relates also to a connecting duct for such an air filter arrangement. 
     BACKGROUND 
     In known air filter arrangements for a combustion engine, particularly an engine of a truck the filter housing often has a releasable bottom which allows a spent filter unit to be taken out and replaced from below, i.e. from the dirty lower side of the arrangement. Although the filter change takes place from the dirty side, there is still risk that in the limited space under the vehicle the new filter unit may scrape against the dirty region in and outside the filter housing, potentially leading to dirt making its way into the filter unit and thereby to the clean side of the air system, and hence to possible damage to the engine. Such a filter change also involves a considerable amount of work and use of space, particularly as the vehicle has to be raised or placed over a greasing pit or the like in a workshop to provide space for the work involved in the change. The operation may comprise removing the bottom of the filter housing, taking out the spent filter unit, cleaning the inside and bottom of the housing, inserting the new filter unit and refitting the bottom. 
     It would therefore be desirable to be able to change the filter from the upper side of the filter housing. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to propose a filter arrangement of the kind indicated in the introduction wherein the filter unit can be changed in a simpler way, with little risk of contamination of the clean side of the filter arrangement. 
     In one aspect of the invention the arrangement has a cover for closing a top aperture of the filter housing, an engine air outlet on the cover and a flexible pipe section on the engine air outlet for the connection to the duct, to allow the cover to be removed from the top aperture and a filter unit to be introduced into and taken out of the filter housing when the housing is connected to the duct. 
     This arrangement thus makes it possible for the filter unit to be changed from the upper side of the arrangement without removing the closed duct system between the filter housing and the engine, thus facilitating the work and avoiding the need to raise the vehicle or place it on a greasing bridge or over a greasing pit. 
     In one embodiment the pipe section is deformable like a roll bellows. This makes it possible for it to be turned inside out, possibly with manual assistance from the service technician undertaking the filter change, and thus be shortened so that the cover can be moved away from the top aperture of the filter housing. 
     If the flexible pipe section has a narrowing cross-section in a direction of flow, the turning inside out may be facilitated so that the larger cross-section nearest to the cover will be on top of the narrower cross-section nearest to the duct to the engine. 
     The flexible pipe section may further be adapted to being slid over the engine air outlet and the duct, making it possible for it to be supported by them so that it does not collapse during operation. An end portion of the duct may then also serve as unrolling support for the flexible pipe section when the cover is opened for filter change or other servicing. 
     The pipe section may further have a curved portion. Configuring the pipe section in a suitable way will then it make it possible to pivot the cover up from the filter housing to leave space for filter change. 
     The cover may then be connected to the filter housing via a hinge. 
     For adaptation to the hinge, a middle line of the curved portion may run at approximately constant distance from the hinge. 
     The engine air outlet may then also be covered by a filter element. Such a filter element, which may comprise a filter cloth or a fine-mesh grille on the cover, provides protection against contamination of the clean side with the ducts to the engine when the cover is removed for filter change. 
     Other features and advantages of the invention may be indicated by the claims and the description of an embodiment example set out below. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view obliquely from above of an air filter arrangement according to the invention; 
         FIG. 2  is a longitudinal sectional view corresponding to  FIG. 1  with cover open; 
         FIG. 3  is a longitudinal sectional view approximately as per  FIG. 2  with air filter partly pulled out; 
         FIG. 4  is a detail view, with portions cut away, of an upper portion of an air filter arrangement according to the invention; 
         FIG. 5  is a detail view, with portions cut away, of a lower portion of an air filter arrangement according to the invention; 
         FIG. 6  is a side view with, portions cut away, of an upper portion of an air filter arrangement according to the invention with cover closed; 
         FIG. 7  is a view corresponding to  FIG. 6  with cover open; and 
         FIGS. 8A-8C  depict schematically a process of opening the cover of an arrangement substantially according to  FIGS. 6 and 7 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Throughout the drawings, the same reference numerals are used for items with same or similar functions. 
     The air filter arrangement depicted in the drawings comprises in a known way an elongate air filter housing  10  for accommodating a filter unit or cartridge  50  comprising a substantially semicylindrical air filter  52 . Air which is to be filtered passes through an air inlet  20  ( FIG. 1 ) on the outside of the filter housing  10  into an annular space between the filter unit  50  and the filter housing  10  and, after passing through the filter  52 , proceeds through an engine air outlet  40  in a cover  30  on the upper side of the filter housing  10 . This engine air outlet  40  is itself intended to be connected to an undepicted air intake of a combustion engine via successive air ducts  42 ,  80 . 
     As most clearly depicted in  FIG. 4 , the filter  52  of the filter unit  50  is connected to a filter top in the form of an upper seal element  60  which has a central aperture  62  coaxial with an inside of the filter  52  and with the air outlet  40 . When the filter unit  50  is fitted in the housing  10 , the outer periphery of the seal element  60  abuts sealingly against an edge  14  which delineates a top aperture  12  of the housing. Centering means of the housing  10  and/or the filter top  60 , e.g. an encircling protrusion  67  directed downwards from the underside of the filter top  60 , may facilitate and ensure that the filter top  60  reaches a correct position at the upper side of the housing  10 . 
     Between the filter unit&#39;s  50  upper seal element  60  and the engine air outlet  40  there is an air aperture  64  ( FIG. 4 ) to an extra air outlet  36 . As indicated by the arrows in  FIG. 4 , part of the filtered air may then also be led to an encircling air duct  66  via an air aperture  64  between the cover  30  and the upper seal element  60  before making its way out through the extra air outlet  36 . The air duct  66  may be delineated radially outwards by an encircling ridge  69  which is part of the upper seal element  60  and which abuts sealingly against the cover  30 . In the example depicted, the extra air outlet  36 , which may distribute filtered air in the arrangement to an undepicted air consumer, e.g. an air compressor, is situated in the filter housings  10  cover  30 . The air aperture  64  extends along a periphery of the engine air outlet  40 , with advantage round the whole periphery, in the form of a gap which slopes obliquely outwards and upwards. The width of the gap may be maintained by supports, e.g. a plurality of evenly distributed bulges  68  which may, as desired, be situated on the upper seal element  60  ( FIG. 3 ) or on the cover  30 . 
     As most clearly illustrated by the simplified depiction in  FIG. 5 , the filter unit&#39;s  50  filter  52  is also connected to a filter bottom in the form of a lower seal element  70 . When the filter unit  50  is fitted in the housing  10 , the outer periphery of the lower seal element  70  abuts sealingly against a lower circumferential edge  18  which delineates a bottom aperture  16  ( FIG. 3 ) of the housing. This bottom aperture  16  allows dirt, cleaning agents and other particles to make their way out of the housing  10  when it is being cleaned, e.g. on the occasion of change of the filter unit. Centering means of the housing  10  and/or the filter bottom  70 , e.g. an encircling protrusion  72  directed downwards from the underside of the filter bottom  70 , may facilitate and ensure that the filter bottom  70  also reaches a correct position at the lower side of the housing  10 . 
     Although other solutions are possible, the aforesaid cover  30  in  FIGS. 1-3  and  FIGS. 6-7  is depicted as being connected pivotably to the filter housing  10  via a hinge  38  situated at an upper outside of the housing  10 . The cover&#39;s  30  air outlet  40  may further be covered by a filter element  34  ( FIG. 2 ), e.g. a filter cloth and/or a fine-mesh grille, to prevent contaminants and solid particles from entering the air ducts  40 ,  80  when the cover  30  is open. The cover  30  may be fastened to the housing  10  by suitable connecting means, e.g. undepicted tightening screws or other kinds of fastenings. 
     In the embodiment depicted in  FIGS. 6 and 7 , the air duct  40  situated nearest to the cover  30  is provided with a collapsible or flexible pipe section  42  which allows repeated opening and closing of the cover  30  without removal from or movement of the fixed air duct  80  situated nearest to the engine. In the embodiment depicted, the pipe section  42  is provided with a narrowing curved portion C made of bendable rubber elastic material which, like a roll bellows, allows the larger cross-section nearest to the cover  30  to be turned inside out, with or without help from a service technician, over the narrowing cross-section nearest to the air duct  80 , approximately as depicted in  FIG. 7 , when the cover  30  is being opened. In a functional state, the pipe section  42  is stretched over the engine air outlet  40  and the air duct  80 . A middle line of the curved portion may then extend at approximately constant distance R from the cover&#39;s hinge  38 . 
       FIGS. 8A-8C  depict in more detail an opening process of an arrangement substantially corresponding to that in  FIGS. 6 and 7 . The air ducts  40  and  80  extend relatively far into the flexible pipe section  42  in order to support it and prevent its collapsing during operation. As indicated in  FIG. 8B , the cross-section of the pipe section  42  between the ducts may in various ways, e.g. by material notches or built-in stresses, be arranged to be drawn together somewhat or deformed radially inwards when the cover  30  starts opening. The larger duct  40  connected to the cover  30  will then be situated round and spaced from the narrower duct  80 . When thereafter the cover in  FIG. 8C  approaches the open state which allows an undepicted filter unit to be taken out of the filter housing  10 , a roll lobe  44  may naturally form on the portion of the pipe section  42  which is supported on an end portion of the narrower duct  80  so that the pipe section  42  unrolls like a roll bellows on this end portion. 
     In this and other embodiments, the cover  30  need not necessarily be connected pivotably to the remainder of the housing  10 , as it may also in an undepicted way be capable of being completely lifted away from the housing  10 . 
     The detailed description set out above is primarily intended to facilitate understanding and no unnecessary limitations of the invention are to be construed therefrom. The modifications which will be obvious to one skilled in the art from perusing the description may be effected without departing from the concept of the invention or the scope of the claims set out below.