Abstract:
A rotating radiator screen has a series of fins surrounding the peripheral edge of the screen at its interface with a wall surface of the machine on which the screen is mounted. An annular baffle on the wall surface circumscribes the fins and cooperates with them in producing positive pressure and an axially outwardly moving curtain of air in the vicinity of the interface so as to oppose the ingress of ambient air and foreign materials at that location.

Description:
TECHNICAL FIELD 
     The present invention relates to rotating radiator screens of the type used, for example, on agricultural machines such as combine harvesters. More particularly, it relates to a way of obtaining an improved dynamic seal at the interface between the rotating screen and a wall surface of the machine so that debris-laden ambient air is forced to pass through and be filtered by the screen as it is drawn into the machine rather than slip in through the interface. 
     BACKGROUND AND SUMMARY 
     Rotating radiator screens are well known in the art. They are used to filter debris from an ambient air stream as it is drawn into the engine compartment of a work machine such as a combine harvester for cooling and other purposes. Typically, materials filtered from the airstream cling to the outside of the rotating screen until passing a “dead spot” that blocks incoming flow and causes the materials to lose their adhesion to the screen and drop off. 
     In spite of the long history of rotating radiator screens and a variety of improvements over the years, there still remains a problem in reliably sealing the interface between the rotating screen and the sidewall or other wall surface of the machine to prevent materials from being sucked into the machine without first passing through the screen itself. Various of kinds of mechanical seals have been tried over the years, including resilient skirts and the like, but none has been totally satisfactory for a number of reasons. 
     Accordingly, an important object of the present invention is to provide an improved dynamic sealing arrangement at the interface between the rotating screen and the adjacent wall surface so that debris-laden ambient air is discouraged from entering the machine through the interface and is instead forced to enter through the screen itself and be subjected to the filtering action that the screen provides. To this end, instead of attempting to block the entry of ambient air by mechanical or physical means at the interface, the present invention relies upon the creation of positive pressure in the region of the interface instead of suction pressure so as to repel the ambient air and the foreign materials carried thereby. In effect, a type of outflowing “air curtain” is created at the interface that moves in a generally axial direction at that location to prevent the ingress of ambient air to the interior of the machine without first passing through the filter surfaces of the screen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational view of a rotating radiator screen in accordance with the present invention in use on an exemplary form of work machine, in this instance a combine harvester; 
         FIG. 2  is an enlarged isometric view of the screen and adjacent wall surfaces of the harvester, as well as the internal combustion engine of the harvester whose cooling equipment is cooled by ambient air entering the machine via the rotating screen; 
         FIG. 3  is an isometric view similar to  FIG. 2  but illustrating the door upon which the screen is mounted in an open condition to reveal the cooling equipment of the machine and details of construction of the rotating screen and associated structures; 
         FIG. 4  is an exploded isometric view of the screen and door upon which it is mounted; 
         FIG. 5  is an enlarged, fragmentary isometric view of the peripheral edge of the rotating screen illustrating details of the air-impinging fins at that location; 
         FIG. 6  is an enlarged cross-sectional view through the interface between the rotating screen and the adjacent wall surface taken substantially along sight line  6 - 6  of  FIG. 2  and illustrating the way in which the fins create a positive pressure air curtain on the outside of the screen; 
         FIG. 7  is a bottom isometric view of a portion of a fin ring segment at the periphery of the screen as viewed in a direction similar to that of  FIG. 5 ; 
         FIG. 8  is an outer edge view of the fin ring segment rotated 90° from the  FIG. 7  orientation; 
         FIG. 9  is a top plan view of the fin ring segment rotated 180° from the  FIG. 7  orientation and generally viewed from the same direction as  FIGS. 2 and 4 ; 
         FIG. 10  is a slightly enlarged isometric view of the fin ring segment taken from a viewing direction somewhat similar to  FIG. 9 ; and 
         FIG. 11  is a front isometric view of the fin ring segment taken from a radially outboard vantage point. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
     The combine harvester  10  illustrated in  FIG. 1  is shown as one example of the type of machine with which a rotating radiator screen in accordance with the present invention may be utilized. In the illustrated embodiment, a rotating screen assembly  12  is mounted on the side of harvester  10  in a position for filtering ambient air as it is drawn into the engine compartment of the harvester. 
     As shown in  FIGS. 2 ,  3 , and  4 , screen assembly  12  is mounted on a suitable wall surface of harvester  10  having an inlet through which ambient air passes as it travels to the engine compartment. In the illustrated embodiment, such wall surface comprises the outer surface  14  of a door  16  hinged for swinging movement about a vertical axis between a closed position as illustrated in  FIG. 2  and an open position as illustrated in  FIG. 3 . An open box frame  18  supports door  16  and houses heat exchange equipment in the form of a cooling core  20  of the harvester and radiator sections  19  and  21  behind core  20 . A rotating fan (not shown) associated with an internal combustion engine behind core  20  and radiator sections  19 ,  21  draws ambient air into heat exchange relationship with core  20  and radiator sections  19 ,  21 . 
     Door  16  has a centrally disposed, circular air inlet  24  that is circumscribed by a circular flange ring  26  secured to and projecting axially outwardly from exterior surface  14  of door  16 . A framework  28  on door  16  spans inlet  24  and has portions that project axially outwardly from inlet  24  to rotatably support a driven shaft  30  that defines the axis of rotation of screen assembly  12 . At its axially inner end, shaft  30  has a large pulley  32  that is wrapped by an endless, flexible drive belt  34 . Belt  34  is looped around and driven by a small sheave  36  fixed to the output shaft  38  of a drive motor  40  also carried by framework  28 . Motor  40  may take a variety of different forms such as, for example, a hydraulic or electrical motor. A spring-loaded idler pulley  42  maintains tension in belt  34 . 
     Screen assembly  12  includes a generally drum-shaped, cylindrical screen  44  and a series or ring of air-flow-inducing fins  46  secured to screen  44  at an axially inner, peripheral edge  48  thereof. Screen  44  has an annular sidewall  50  and a circular endwall  52  at the axially outer end thereof. Both sidewall  50  and endwall  52  are formed from suitable foraminous material having openings or interstices that are of sufficient size to screen out undesirable trash and residue as it attempts to pass through screen  44  into inlet  24 . Screen assembly  12  is secured to shaft  30  via a mounting plate  54  at the outer end of shaft  30 , which plate  54  is attached to endwall  52 , thus rendering screen assembly  12  rotatable by motor  40 . 
     Framework  28  within the interior of screen assembly  12  supports a blocking member  56  ( FIG. 4 ) that creates a dead zone in the rotary path of travel of screen assembly  12  so that particles clinging to the sidewall  50  and endwall  52  of screen  44  drop off when they pass blocking member  56 . As shown in  FIG. 4 , blocking member  56  includes a generally triangular upright plate  58  forming a dead zone for the endwall  52  of screen  44  and an arcuate base  60  extending axially inwardly from the radially outer extremity of plate  58  for cooperating with sidewall  50 . 
       FIGS. 5-11  illustrate details of construction of the ring of fins  46  and their relationship to the wall surface  14  of door  16 . As seen in those figures, a band  62  of annular configuration is fixed to screen sidewall  50  at the axially inner end thereof and serves to define peripheral edge  48  of screen  44 . A flat, annular mounting lip  64  circumscribes band  62  at a distance spaced axially outwardly from peripheral edge  48  and is fixed to band  62  so as to provide a means of mounting the ring of fins  46  to screen  44 . The ring of fins  46  is fixedly secured to lip  64  by rivets  66  or other suitable means. 
     In a preferred embodiment, the ring of fins  46  is presented by multiple arcuate fin segments  68  such as shown in  FIGS. 7-11  that are arranged end-to-end around the periphery  48  of screen  44  to form a complete ring. In a most preferred embodiment, each segment  68  can be manufactured from sheet metal which is cut and stamped to produce a number of individual fins  70  at spaced apart locations along a flat base  72  from which fins  70  project. Base  72  is butted up against lip  64  and secured thereto by the rivets  66 . Holes  74  in base  72  provide clearance for rivets  66 . 
     Each fin  70  is integrally attached to the base  72  by a generally triangular leg  76  lying in the plane of base  72 . Each fin  70  is generally rectangular, although it will be seen from the drawings that the body of each fin widens progressively as the leading extremity is approached. Each fin  70  also presents an inclined, flat front face  78  that is sloped back with respect to the direction of rotation of screen assembly  12  as indicated by the arrow R in the figures. This is a counterclockwise direction as  FIGS. 1 ,  2  and  4  are viewed. 
     Due to the sloped back nature of each fin  70 , the axially innermost edge  80  of each fin  70  leads in the direction of rotation R, while the axially outermost edge  82  of fin  70 , where it is joined to leg  76 , trails. In addition, each fin  70  is outturned slightly such that face  78  is similarly outturned in a radial direction so that the radially inboard edge  84  of each fin  70  leads in the direction of rotation R while the radially outboard edge  86  trails. Thus, each fin  70  is inclined and canted in a manner to push air forwardly with respect to the direction of rotation R and radially outwardly with respect to the axis of rotation defined by drive shaft  30 . 
     The inside diameter of screen assembly  12  is greater than the outside diameter of flange ring  26 . Thus, as shown particularly in  FIG. 6 , sidewall  50  of screen assembly  12  circumscribes flange ring  26  and is spaced radially outwardly therefrom a short distance so as to define an annular void region  88 . Additionally, the dimension of sidewall  60  in the axial direction is such that peripheral edge  48  at the axially inner end of band  62  is spaced a short distance axially outwardly from wall surface  14  of door  16 , presenting an annular gap  90  in open communication with region  88 , which is in turn in open communication with the interior of screen  44 . As shown also in  FIG. 6 , fins  70  are of such size that the axially innermost edge  80  thereof is spaced axially outwardly from wall surface  14  to provide ample running clearance between fins  70  and wall surface  14 . Thus, at the interface between screen assembly  12  and wall surface  14  there is no physical contact between those components. 
     An annular baffle  92  surrounds fins  70  in radially outwardly spaced relation thereto and is fixed to wall surface  14 . Baffle  92  projects axially outwardly from wall surface  14  for a distance less than flange ring  26  such that baffle  92  is shorter than flange ring  26 . In one preferred embodiment, baffle  92  is approximately one-half the length of flange ring  26 . Baffle  92  has an inside diameter that is somewhat larger than the diameter of the circle defined by outboard edges  86  of fins  70  so as to provide ample running clearance for fins  70 . The height of baffle  92  in the axial direction is such that fins  70  project a short distance axially outwardly beyond baffle  92  as shown in  FIG. 6 . It will be appreciated that baffle  92  and flange ring  26  effectively define an annular channel  84  within which fins  70  and the peripheral edge  48  of screen  44  travel during rotation of screen assembly  12 . 
     Operation 
     As motor  40  rotates screen assembly  12  in a counterclockwise direction viewing  FIGS. 1 ,  2  and  4 , ambient air is drawn into inlet  24  by the fan (not shown) associated with engine  22 . In order to reach inlet  24 , however, the air must first pass through screen  44 , including sidewall  50  and endwall  52  thereof. Consequently, debris is filtered out of the air stream by screen  44  and becomes adhered to sidewall  50  and endwall  52 . However, as screen  44  rotates past blocking member  56 , the adhered materials are dropped from screen  44  due to a lack of suction pressure in that area. Thus, screen  44  continuously sheds itself of adhered materials and does not become clogged. 
     As screen assembly  12  rotates, fins  70  travel within channel  94 . Front faces  78  of fins  70  impinge upon the air in channel  94  and force it in an axial direction along the exterior of sidewall  50  and away from wall surface  14 . Baffle  92  is instrumental in confining and directing the airflow axially outwardly away from wall surface  14  at this time, helping to create a region of positive pressure within channel  94  and an axially outwardly moving curtain of air that surrounds sidewall  50  for a short distance beyond the outer end of baffle  92 . Due to the presence of annular region  88  and gap  90 , some of the ambient air that has been drawn into the interior of screen  44  through sidewall  50  and end wall  52  moves along the outside of flange ring  26  through region  88  into channel  94  to continuously supply air for the curtain produced by fins  70  and baffle  92 . 
     As a result of the present invention, air-borne debris is not drawn into the interior of screen assembly  12  at the interface between wall surface  14  and peripheral edge  48 . Instead, it is repelled by the positive pressure within channel  94  and the moving air curtain. Instead of attempting to solve the sealing problem by obtaining a more effective mechanical seal between physically contacting, relatively moving surfaces at that location, a relatively friction-free air curtain seal with positive pressure outflow is created, providing many significant benefits. 
     The inventor(s) hereby state(s) his/their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his/their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.