Abstract:
An air cleaner is provided with a reduced restriction precleaner cooperating with a tangential inlet and centering and locating an annular filter element, and reducing inlet restriction.

Description:
BACKGROUND AND SUMMARY 
   The invention relates to air cleaners, and more particularly to air cleaners having a tangential inlet and a precleaner. 
   Air cleaners with a tangential inlet and a precleaner are known in the prior art. Such air cleaners typically have a cylindrical housing and provide two stage cleaning, namely a precleaner provided by flow from the tangential inlet along a spiral path, and a second stage provided by radial inward flow through an annular filter element. The precleaner is typically provided by an annular sleeve circumscribing the annular filter element and spaced radially inwardly of the interior surface of the cylindrical sidewall of the housing by a radial gap defining an annular flow channel between the sleeve and the interior surface of the cylindrical housing sidewall. A ramp in the channel may direct air flow along a helical pattern. The sleeve also helps to locate and center the annular filter element within the housing. While the sleeve provides the noted desirable functions, it also contributes to restriction of the air flow as it enters the housing, which restriction is undesirable. 
   The present invention addresses the noted restriction disadvantage, and provides a sleeve which desirably facilitates the noted helical air flow pattern for precleaning and also facilitates location and centering of the annular filter element within the housing, and which reduces entry restriction to air flow suffered by prior sleeves. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Prior Art 
       FIG. 1  is an isometric view of an air cleaner known in the prior art. 
       FIG. 2  is an exploded perspective view of the air cleaner of  FIG. 1 . 
       FIG. 3  is a sectional view taken along line  3 — 3  of  FIG. 1 . 
       FIG. 4  is an elevation view of the inlet of the air cleaner of  FIGS. 1–3 . 
       FIG. 5  is a perspective view partially cutaway of a portion of the air cleaner of  FIG. 1 . 
     Present Invention 
       FIG. 6  is a view like  FIG. 3  and shows an embodiment of the present invention. 
       FIG. 7  is a view like  FIG. 4  and shows the embodiment of the present invention illustrated in  FIG. 6 . 
       FIG. 8  is a view like  FIG. 5  and shows the embodiment of the present invention illustrated in  FIGS. 6 and 7 . 
       FIG. 9  is a view like  FIG. 7  and shows another embodiment of the present invention. 
       FIG. 10  is a sectional view taken along line  10 — 10  of  FIG. 9 . 
       FIG. 11  is a view like  FIG. 8  and shows the embodiment of the present invention illustrated in  FIGS. 9 and 10 . 
       FIG. 12  is a view of the cylindrical sleeve and air flow channel of the embodiment of  FIGS. 9–11  unrolled and laid out in a flat profile view. 
   

   DETAILED DESCRIPTION 
   Prior Art 
     FIG. 1  shows an air cleaner  20  including a cylindrical housing  22  extending axially along an axis  24  and having a tangential inlet  26  and having an outlet  28 . An annular filter element  30 ,  FIGS. 2 ,  3 , in housing  22  has a dirty side  32  receiving dirty air from inlet  26  and having a clean side  34  delivering clean filtered air to outlet  28 . Air entering housing  22  through tangential inlet  26  as shown at arrow  25  flows along an interior surface  36  of housing  22  in a helical spiral pattern  38  about axis  24 , and flows radially inwardly through annular filter element  30  into the latter&#39;s hollow interior  40  and then flows axially through outlet  28  as shown at arrow  42 . Housing  22  is typically a two-piece plastic assembly provided by upper housing section  44  and lower housing section  46  joined by a twist and lock structure  48 , for example as shown in U.S. Pat. No. 6,402,798, incorporated herein by reference. Lower housing section  46  may have a purge valve  50  for periodically discharging collected particulate due to the precleaning provided by the centrifugal separation afforded by helical pattern  38 , as is known. 
   An annular shielding sleeve  52  is integrally formed as part of the upper housing section  44  and circumscribes annular filter element  30  and is spaced radially inwardly of interior surface  36  of the sidewall of the housing by a radial gap  54  defining an annular flow channel between sleeve  52  and interior surface  36  of the sidewall of the housing. Filter element  30  has upper and lower axial ends covered by respective upper and lower axial end caps  56  and  58 ,  FIG. 2 , which end caps may form axial and/or radial seals with respective upper and lower housing sections  44  and  46 , all as is known. Upper end cap  56  is at tangential inlet  26  and has an axial height  60 ,  FIGS. 2 ,  3 . Tangential inlet  26  has an axial height  62  greater than axial height  60  of end cap  56 . Sleeve  52  has an axial height  64  greater than axial height  62  of tangential inlet  26 . 
   Housing  22  at upper section  44  has a ramp  66  in channel  54  directing air flow along the noted helical pattern  38 . Ramp  66  has a leading end  68  and has a trailing end  70 . The ramp has a minimum axial height at leading end  68 , and has a maximum axial height at trailing end  70 . The axial height  64  of sleeve  52  is greater than the maximum axial height of ramp  66  at trailing end  70 . The lower axial end  72  of sleeve  52  is viewable in  FIG. 3 , and is shown in dashed line in  FIGS. 1 ,  4 ,  5 . 
   Present Invention 
     FIGS. 6–12  illustrate the present invention and use like reference numerals from above where appropriate to facilitate understanding. 
   In  FIG. 6 , annular shielding sleeve  102  circumscribes annular filter element  30  and is spaced radially inwardly of interior surface  36  of the cylindrical sidewall of housing  22  by a radial gap  104  defining an annular flow channel between sleeve  102  and interior surface  36  of the sidewall of the housing. Sleeve  102  has an axial height  106  greater than or equal to axial height  60  of end cap  56  and less than axial height  62  of tangential inlet  26 . This reduces the restriction to incoming air flow through tangential inlet  26  at arrow  25 . 
   Axial height  106  of sleeve  102  is less than the maximum axial height of ramp  66  at trailing end  70 . The lower axial end  108  of sleeve  102  is shown in  FIGS. 6 and 8 , and is shown at solid line in the right portion of  FIG. 7  and dashed line in the left portion of  FIG. 7 . Ramp  66  has a first segment  110  extending circumferentially and axially along sleeve  102  from leading end  68  of the ramp to an intermediate portion  112  of the ramp. Ramp  66  has a second segment  114  extending circumferentially and axially beyond sleeve  102  at lower edge  108  from intermediate portion  112  of the ramp to trailing end  70  of the ramp. Intermediate portion  112  of ramp  66  has an axial height  116 ,  FIG. 7 , equal to axial height  106  of sleeve  102 . The entire circumferential length of second segment  114  of ramp  66  from intermediate portion  112  to trailing end  70  has an axial height greater than axial height  106  of sleeve  102 . 
     FIGS. 9–12  show a further and preferred embodiment of the present invention and use like reference numerals from above where appropriate to facilitate understanding. In  FIGS. 9–12 , sleeve  102  is replaced by a sleeve  132  having an axial height tapered at  134  along a portion of its circumference at a location aligned with tangential inlet  26 , such that incoming air at  25  through tangential inlet  26  does not initially encounter a full axial height sleeve, as at  52  in  FIGS. 1–5 , and preferably not even a partial axial height sleeve as at  102  in  FIGS. 6–8 , but instead encounters a tapered sleeve of increasing axial height from lowest axial height at  136  to highest axial height at  138 , whereby to reduce initial flow restriction at air inflow  25 . 
   Tapered portion  134  of sleeve  132  has a leading end at  136  and a trailing end at  138 . Annular flow channel  140  formed by the radial gap between annular filter element  30  and interior surface  36  of the cylindrical sidewall of the housing has a first circumferential section  142  of increasing axial depth to air flow therealong from leading end  136  of tapered portion  134  of sleeve  132  to trailing end  138  of tapered portion  134  of sleeve  132 . The channel has a second circumferential section  144  directing air flow therealong from trailing end  138  of tapered portion  134  of sleeve  132 . Ramp  66  in channel  140  directs air flow along helical pattern  146 . Circumferential section  144  of channel  140  directs air flow therealong from trailing end  138  of tapered portion  134  of sleeve  132  to leading end  68  of ramp  66 . Channel  140  has a third circumferential section  148  directing air flow therealong from leading end  68  of ramp  66 . Third circumferential section  148  of channel  140  has a decreasing axial depth to air flow therealong. Air flow entering tangential inlet  26  encounters increasing axial channel depth along first circumferential section  142  of channel  140  and then is directed through second circumferential section  144  of channel  140  and then encounters decreasing axial channel depth along third circumferential section  148  of channel  140 . 
   Tangential inlet  26  is axially between leading end  136  of tapered portion  134  of sleeve  132  and trailing end  70  of ramp  66  such that leading end  136  of tapered portion  134  of sleeve  132  and trailing end  70  of ramp  66  are on axially distally opposite sides of tangential inlet  26 . Trailing end  138  of tapered portion  134  of sleeve  132  and leading end  68  of ramp  66  are on circumferentially distally opposite sides of tangential inlet  26 . Axial height  150 ,  FIG. 10 , of sleeve  132  at trailing end  138  of tapered portion  134  of the sleeve, which in the preferred embodiment is the same as axial height  106  of sleeve  102 ,  FIG. 6 , is less than the axial height of ramp  66  at trailing end  70 . Ramp  66  has the noted first segment  110  extending circumferentially axially along sleeve  132  from leading end  68  of the ramp to intermediate portion  112  of the ramp, and the ramp has the noted second segment  114  extending circumferentially and axially beyond sleeve  132  at lower end  133  from intermediate portion  112  of the ramp to trailing end  70  of the ramp. The axial height of sleeve  132  at trailing end  138  of tapered portion  134  of the sleeve is less than the axial height  62  of tangential inlet  26 . 
   It is recognized that various equivalents, alternatives and modifications are possible within the scope of the appended claims.