Abstract:
A passive fan blade for a cooling package for use in an agricultural combine comprises a generally rectangular member having an axis, a central mounting area and two opposed legs, each leg having a middle region, a leading region and a trailing region, the leading and trailing regions being angled toward the downstream direction of intended air flow. The trailing regions increase in width in proportion to distance from the axis, while the leading regions decrease in width in proportion to distance from the axis, whereby the member is impelled to rotate in the direction of the leading edges when air flows past the member. In an assembly, the passive fan blade is mounted via a bearing assembly and mounting hardware onto a hub connected to a bracket. In a cooling package, the passive fan blade assembly is mounted on a frame in close proximity to a face of a radiator or a charge air cooler to provide turbulence thereby minimizing accumulation of chaff, dust and debris in order to maintain cooling efficiency.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to a passive fan blade for a cooling package for use in an agricultural combine, particularly, it relates to keeping faces of a radiator and a charged air cooler clean of debris. 
     2. Description of the Related Art 
     An agricultural combine typically includes a cooling package which may include a radiator and a charged air cooler, each of which has a heat exchanger core with an upstream face, mounted into a frame. The cooling package circulates air through a heat exchanger core in the radiator to reject heat from the engine and other working parts of a combine, and through a heat exchanger core in the charged air cooler to cool air compressed in a turbocharger to make it more dense and allow more oxygen to be fed to cylinders of a engine. An agricultural combine provides a unique problem because of the environment it is in. In the hot environment of a combine, it is necessary to circulate a large volume of air through the cores to reject the large amount of heat produced by the engine, and to push as much air into the cylinders to get as much power out of the engine as possible. Because the environment of a combine is filled with dust and chaff, inevitably the dust and chaff will build up on the upstream faces of the heat exchanger cores, blocking a path of air flow. As the upstream faces become more and more blocked, heat transfer efficiency decreases. The decrease in heat transfer efficiency can lead to engine overheating and loss of power. 
     Previous attempts to alleviate the problem have included attempts to use passive fan blades immediately upstream of the front faces of the heat exchanger cores. 
     A passive fan blade acts to break up the debris that forms on the face of the core by making the air more turbulent at the face. It is called “passive” because it is not driven by anything other than the passage of air over the blade, the air being drawn by a powered fan on the downstream end of the cooling package. Passive fan blades have included regions that are angled toward the downstream direction of air flow. The angled regions of the fan blades have caused the blades to rotate in response to the air flow. 
     The addition of passive fan blades has aided in keeping the heat exchanger core faces clean, however, the fan blades have not rotated dependably and reliably and in some cases have failed to rotate altogether. When the blades have rotated, they have not created enough turbulence to keep the upstream faces of the cores clean for a substantial period of time. It has been necessary to clean the cooling package so frequently that a farmer who is harvesting crops would have to stop several times a day to clear out the upstream face of the cooling package. 
     Although placing passive fan blades in front of the faces of the heat exchanger cores has assisted in the breaking up the debris and keeping the faces clean, the passive fan blades have not dependably and reliably provided enough turbulence to allow a farmer to continually harvest crops for an extended period of time. 
     Therefore, what is needed is a passive fan blade and system that will create enough turbulence to allow the upstream face of the heat exchanger cores to remain relatively clean for a full day of harvesting. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a passive fan blade for a cooling package for an agricultural combine that will reliably rotate at a predetermined rotational speed and provide enough turbulence to maintain a relative clean upstream face of a radiator and a charge air cooler of the cooling package. 
     It is another object of the present invention to minimize a clearance distance between a passive fan blade and upstream faces of the radiator and the charge air cooler of the cooling package. 
     It is another object of the present invention to provide a set of bearings for a passive fan blade that allows the fan blade to spin at the predetermined rotational speed that creates a high turbulence at the upstream faces of the radiator and the charge air cooler for the cooling package. 
     It is a feature of the present invention to provide a passive fan blade for cleaning upstream faces of a radiator and a charge air cooler for a cooling package of a combine. It has been determined that important factors that establish turbulence on the upstream face of the heat exchanger cores are rotational speed of the passive fan blades, clearance distance from the fan blade to the upstream face of the heat exchanger cores where the smaller the clearance distance, the more turbulence is created, and bearings that allow the fan blade to turn. To accomplish a desired level of turbulence, what is needed is a passive fan blade with a clearance distance as small as possible, a rotational speed that maximizes turbulence, and a set of bearings that maximizes turbulence. 
     The passive fan blade includes a rectangular-shaped member which has a center, a length and a width where the length is substantially greater than the width, an axis passing perpendicularly through the center of the member, and a mounting area generally at the center of the member. The mounting area has one larger hole for mounting a bearing housing described later, and a plurality of smaller mounting holes for receiving mounting bolts for a bearing assembly described later. The member is defined by two diametrically opposed legs, each with a middle region generally perpendicular to the direction of air flow, a leading region having an edge and a trailing region having an edge. Both the leading regions and the trailing regions are angled toward the downstream direction of airflow with respect to the middle regions, where the angles are between about 15 and about 30 degrees, with a preferred angle being about 20 degrees. The leading regions decrease in width as a distance from the axis is increased until it reaches a minimum width near the distal end of about 3% to about 15% of the total width of the member with a preferred width of the leading region at its minimum being about 11% of the total width of the member. The trailing regions increase in width as a distance from the axis is increased until it reaches a maximum width near the distal end of about 35% to 50% of the total width of the member with a preferred width of the trailing region at its maximum being about 45% of the total width of the member. As air flows past the member, a greater force is imparted on the trailing regions than on the leading regions, causing the fan blade to rotate in the direction of the leading regions. 
     One or two passive fan blades may be attached to a bracket having an upstream surface, and a downstream surface. Each blade has a corresponding hub that is generally of a cylindrical shape and is attached to the downstream surface of the bracket. A bearing assembly is attached to each hub using a set of mounting hardware, the bearing assembly having a set of bearings, and a bearing housing with a cover. The mounting hardware is also used to attach the bearing assembly to the mounting area of the member of the fan blade. The bearings within the bearing assembly allow the fan blade free rotation as air is passed over the fan blade. Bearing assemblies are chosen so that the fan blades rotate at a predetermined rotational speed, the rotational speed corresponding to a maximum turbulence. Rotational speeds of between about 200 rpm and about 800 rpm have been experimentally determined, with the present embodiment of this fan blade, to be an ideal range of rotational speeds, with a preferred rotational speed of about 400 rpm. 
     The cooling package of a combine may include a frame having outer walls that define an opening within the frame, a radiator with an upstream face, and a charge air cooler with an upstream face, wherein the radiator and the charge air cooler are mounted within the opening in the frame. Two fan blade assemblies are attached to a frame of the cooling package, the bracket of each fan blade assembly being attached to the frame. One bracket is positioned upstream of the radiator of the cooling package, and one bracket is positioned upstream of the charge air cooler. In one embodiment of the invention, the radiator fan blade assembly has one fan blade and the fan blade assembly of the charge air cooler has two fan blades. There is a clearance between the upstream face of the radiator and the radiator fan blade assembly and clearance distances between the upstream face of the charge air cooler and the charge air cooler fan blade assembly. 
     In an alternate embodiment of the invention, the radiator fan blade assembly has two fan blades and the charge air cooler fan blade assembly has two fan blades. Clearances for the radiator fan assembly are between the upstream face of the radiator and each fan blade of the radiator fan blade assembly. Clearances for the charge air cooler fan blade assembly are between the upstream face of the charge air cooler and each of the fan blades of the charge air cooler can blade assembly. 
     The clearances of both embodiments can be between 20 mm and 30 mm, with a preferred clearance of about 25 mm. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a side view of the blade and bracket assembly, and their relationship to the upstream face of a heat exchanger. 
     FIG. 2 is a top view of the blade and bracket assembly. 
     FIG. 3 is an exploded perspective view of the bracket assembly. 
     FIG. 4 is a perspective view of the preferred embodiment with one fan blade for the radiator and two fan blades for the charged air cooler. 
     FIG. 5 is a perspective view of an alternate embodiment with two fans for both the radiator and the charged air cooler. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures, there is shown a novel and improved cooling package  10  for use in an agricultural combine, see FIG.  4 . The inventive cooling package incorporates passive fan blades mounted upstream of a radiator  20  and charge air cooler  22  in order to create added turbulence in air drawn through cooling package  10 , the added turbulence created at upstream surface  24  of radiator  20  and upstream surface  26 , of charge air cooler  22 . The added turbulence advantageously keeps upstream faces  24  and  26  clear of dust and chaff inherent in the environment of an agricultural combine, thereby preventing the blinding over of heat exchanger cores necessary for the operation of combine  14 . 
     As shown in FIGS. 4 and 5, air is drawn through cooling package  10  by a fan (not shown) in the direction of airflow  150 . Cooling package  10  includes a radiator  20  and a charge air cooler  22  combined to form a subassembly as described in copending application with Ser. No. 10/053,514 filed contemporaneously herewith, incorporated by reference as if reproduced in full herein. In the operation of an agricultural combine  10 , upstream face  24  of radiator  20  and upstream face  26  of charge air cooler  22  can become covered with dust and chaff from the environment. In the inventive apparatus a passive fan blade assembly  30  is placed upstream of radiator  20  near upstream face  24  of radiator  20  and a passive fan blade assembly  32 , is placed upstream of charge air cooler  22  near upstream face  26  in order to create turbulence and prevent accumulation of dust and chaff on radiator face  24  and charge air cooler face  26 . 
     As shown in FIG. 4, radiator fan blade assembly  30  includes one passive fan blade  34 . Charge air cooler fan blade assembly  32  is preferred to have two passive fan blades  36 . As the fan blades of assemblies  30  and  32  rotate the fan blades keep upstream faces  24  and  26  relatively clear of dust and chaff by increasing turbulence in the air drawn through cooling package  10 . The passive fan blades of the invention have been shown to be unexpectedly reliable and dependable in maintaining a desired rotational speed, where the rotational speed was found to be most efficient at clearing faces  24  and  26  in a range of about 200 rpm to about 800 rpm, with a preferred rotational speed of about 400 rpm. When radiator  20  is equipped with fan blade assembly  30  and when charge air cooler  22  is equipped with fan blade assembly  32 , upstream faces  24  and  26  remain clean for extended periods of time while a crop is being harvested by combine  12 . 
     It has been surprisingly found that a larger trailing edge and a faster rotational speed of a fan blade does not necessarily relate to more turbulence or result in a cleaner upstream cooling core face. Rather, it was found that the passive fan blade and system of the invention provides a particularly desirable range of rotational speeds that result in maximum turbulence at the face. 
     The present invention includes a desirable fan blade and system that will rotate at a predetermined rotational speed that has been experimentally found to create a level of turbulence that will keep upstream face  24  and  26  relatively clean for an extended period of time. Fan blade  34  of assembly  30  and fan blades  36  of assembly  32  provide necessary added turbulence at radiator upstream face  24  and charge air cooler upstream face  26 . Experimentally determined rotational speeds range from about 200 rpm to about 800 rpm, with a preferred rotational speed of about 400 rpm. Fan blade  34  of radiator fan blade assembly  30  and fan blades  36  of charge air cooler assembly  32  have been designed so that they rotate within the range of rotational speeds of about 200 rpm to about 800 rpm. 
     Turning now to FIGS. 1 and 2, fan blade  34  is made up of a rectangular-shaped member of length L and width W, each member having a center  42 , an axis  44  passing generally through center  42 , a mounting area  46  located generally at center  42  and two diametrically opposed legs  52  with distal ends  56 . The length L of fan blade  34  ranges from about 57.5 cm to about 65 cm, with a preferred range of about 59 cm to about 63 cm, and a still more preferred length of about 61 cm. The widths W of fan blade  34  range from about 7.5 cm to about 9.5 cm, with a preferred range of about 8.5 cm to about 9.1 cm, and a still more preferred width of about 8.8 cm. The ratio of the length of to width for fan blade  34  may be between about 6 to 1 and about 9 to 1, with a preferred ratio of between about 6.5 to 1 and about 7.5 to 1, and a still more preferred length to width ratio for fan blade  34  of about 7 to 1. 
     As best shown in FIGS. 1 and 2, each leg  52  of fan blade  34  has a middle region  60  that is generally perpendicular to airflow direction  150 , a leading region  62  with an edge  64  and a trailing region  66  with an edge  68 . In a preferred embodiment, leading regions  62 . trailing regions  66 , and middle regions  60  are substantially planar. Leading regions  62  and trailing regions  66  are both angled toward the downstream direction of airflow. Angle  70  being defined between leading region  62  and middle region  60  and angle  72  being defined between trailing region  66  and middle region  60 . Values of between about 15 and about 25 degrees, with a preferred range of between about 18 degrees and about 22 degrees, and a still more preferred angle of about 20 degrees for angles  70  and  72  have been experimentally found to allow fan blade  34  to rotate at the desired rotational speeds of between about 200 rpm and about 800 rpm. A larger angle corresponds to more turbulence created at the face, but a fan blade with a larger angle is less likely to spin because the airflow does not have as much surface area to act upon. 
     It was expected that a desirable ratio of width of trailing region  66  to the width of leading region  62  would be large, to create a large difference in forces being exerted on the leading region and trailing region. It has been surprisingly found that it is possible to have a width of trailing region  66  that is too wide and a width of leading region  62  that is too narrow, causing the fan blades to fail to rotate. While this phenomenon is not clearly understood, it may be that an overly large trailing edge creates a large resistance to the air through which the trailing edge rotates. 
     Leading region  62  decreases in width proportional to the distance from center  42  so that it is narrower at distal ends  56 . The width of leading region  62  at its minimum ranges between about 3% and about 15% of the overall width of fan blade  34 , with a preferred width of the leading region at its minimum being about 11% of the overall width of fan blade  34 . 
     Trailing region  66  increases in width proportional to the distance from center  42  so that it is wider at distal ends  56 . The width of trailing region  66  at its maximum ranges between about 35% and about 50% of the overall width of fan blade  34 , with a preferred width of the trailing region at its maximum being about 45% of the overall width of fan blade  34 . 
     Because the corners  74  of trailing edges  68  are closer to upstream face  24  than any other portion of the fan blade (best shown in FIG. 1 ), it is desirable to chamfer trailing region edges  68  at corners  74  so that fan blade  34  can be moved closer to upstream face  24  without increasing the risk of fan blade  34  coming in contact with face  24 . 
     The relatively large width of trailing region  66  and the relatively narrow width of leading region  62  causes a force imparted on fan blade  34  by air flowing past fan blade  34  that is larger at trailing region  66 , causing the fan blade to rotate in the direction of each leading edge  64  because trailing region  66  has a larger surface area than leading region  62 . 
     Fan blades  36  of charge air cooler fan blade assembly  32  have all the same elements as fan blade  34 , except the lengths are different. Lengths of fan blades  36  range from about 38 cm to about 50 cm, with a preferred range from about 41 cm to about 43 cm, and a still more preferred length of fan blades  36  of about 42.5 cm. The ratio of the length of to width for fan blades  36  may be between about 4 to 1 and about 7 to 1, with a preferred ratio of between about 4.5 to 1 and about 5.5 to 1, and a still more preferred length to width ratio for fan blades  36  of about 5 to 1. 
     As shown in FIG. 4, the present invention incorporates one fan blade  34  of radiator fan blade assembly  30  and two fan blades  36  of charge air cooler fan blade assembly  32  into cooling package  10  to clear dust and chaff off of radiator upstream face  24  and charge air cooler upstream face  26 , and to keep the faces relative clear of debris during operation of combine  12  for an extended period of time. 
     Radiator  20  and charge air cooler  22  are mounted within frame  80  of cooling package  10 . Radiator fan blade assembly  30  is mounted to frame  80  immediately upstream of face  24  of radiator  20 . Charge air cooler fan blade assembly  32  is mounted to frame  80  immediately upstream of face  26  of charge air cooler  22 . 
     Turning to FIG. 3, radiator fan blade assembly  30  includes fan blade  34 , a bracket  82 , a hub  84 , and a bearing assembly  88  as well as hardware to mount bearing assembly  88  to bracket  82  and to fan blade  34 . Each bracket  82  has a width large enough so that it is rigid and will not vibrate while the fan blades are rotating, but it also has a width narrow enough so as to not obstruct airflow over fan blade  34 . Bracket  82  has a width of about 2 cm to about 5 cm, with a preferred width of about 3 cm. 
     Hub  84  is attached to the downstream side of bracket  82 . Hub  82  includes a mounting hole  90  for the attachment of bearing assembly  88 . It is preferred that hub  84  be cylindrical in shape, with a cylinder diameter of between about 0.5 cm and about 2.5 cm with a preferred diameter of about 1 cm. 
     As shown in the exploded view of FIG. 3, mounting area  46  of fan blade  34  includes a bearing housing hole  92  and a plurality of bearing mounting holes  94  located generally in the center of fan blade  34 . Bearing assembly  88  includes a set of bearings  96 , a bearing housing  98  and a bearing cover plate  100 . Bearing housing  98  has flanges  102  with holes  104  and bearing cover plate  100  has flanges  106  with holes  108 . Holes  104  in flange  102  and holes  108  in flanges  106  correspond with bearing mounting holes  94  in fan blade  34 . 
     Mounting hardware that is used for the fan blade assembly includes a set of bearing mounting bolts  110 , a set of bearing mounting nuts  112 , a hub mounting bolt  114 , a lock washer  116 , and a washer  118 . Bearing mounting bolts  110  and bearing mounting nuts  112  are used to mount bearing assembly  88  to fan blade  34 . Bearing mounting bolts  110  extend through bearing mounting holes  94  in fan blade  34 , flange holes  104  in bearing housing  98 , flange holes  108  in bearing cover plate  100  and engage bearing mounting nuts  112 . Bearing assembly  88  and fan blade  34  are mounted to hub  84  on bracket  82  using hub mounting bolt  114 , lock washer  116  and washer  118 . Hub mounting bolt  114  extends through lock washer  116  and washer  118 , through the center of bearing assembly  88  mounted in fan blade  34  and engages mounting hole  90  in hub  84 . It is preferred that bearing assembly  88  is generally on the upstream side of fan blade  34 . This corresponds to being on the side of fan blade  34  opposite from upstream faces  24  and  26 , so that bearing assembly  88  will not come in contact with upstream faces  24  and  26 , allowing the fan blade assembly to mounted as close to the faces as possible. 
     Bearings assembly  88  is important to the rotational speed of fan blade  34 . A preferred bearing assembly includes six or seven ball bearings  96 , obtainable from a supplier, preferably model #JD29980. 
     Charge air cooler fan blade assembly  32  includes two fan blades  36 , each fan blade having a corresponding bracket, hub, bearing assembly and mounting hardware as described above for fan blade assembly  30  for radiator  20 . 
     Turning to FIG. 4, in a preferred embodiment, radiator fan blade assembly  30  is placed into cooling package  10  by mounting ends of bracket  82  onto frame  80  so that the center of fan blade  34  is generally centered horizontally and vertically with respect to upstream face  24 . As seen in FIG. 1, clearance  124  is between the middle region  60  of fan blade  34  and upstream face  24  of radiator  20  is preferred to be as small as possible, but practically there is a limit as to how small the clearance can be, because if clearance  124  is too small, any vibrations could result in fan blade  34  coming in contact with upstream face  24  of radiator  20 . Conversely, if clearance  124  is too large, an inadequate amount of turbulence will be created and upstream face  24  will become blinded over with debris such as dust or chaff. A clearance of between about 20 mm and about 30 mm, with a preferred clearance of about 25 mm, has been experimentally determined to be ideal for the present invention. 
     Charge air cooler fan blade assembly  32  is placed into cooling package  10  by mounting ends of bracket  122  onto frame  80  so that the center of each of fan blades  36  of fan blade assembly  32  are generally centered horizontally with respect to upstream face  26  of charge air cooler  22  and so that one fan blade is generally ⅓of the height of charge air cooler  22  away from the top of frame  80  and one fan blade is ⅓of the height of charge air cooler  22  away from the bottom of frame  80 . Clearances between each middle region of fan blades  36  and upstream face  26  of charge air cooler  22  are between about 20 mm and about 30 mm, with a preferred clearance of about 25 mm for the same reasons as stated above. 
     In an alternative embodiment of the radiator fan blade assembly  130  shown in FIG. 5, two passive fan blades  134  are mounted to radiator bracket  182  similar to the arrangement of fan blades  36  of charge air cooler can blade assembly  32 . 
     Each fan blade  134  of fan blade assembly  130  has the same features of fan blade  34 , except the lengths are different. Lengths of fan blades  134  range from about 38 cm to about 50 cm, with a preferred range from about 41 cm to about 43 cm, and a still more preferred length of fan blades  134  of about 42.5 cm. The ratio of the length to width for fan blades  134  may be between about 4 to 1 and about 7 to 1, with a preferred ratio of between about 4.5 to 1 and about 5.5 to 1, and a still more preferred length to width ratio for fan blades  134  of about 5 to 1. 
     Fan blade assembly  130  has all of the same elements as fan blade assembly  30 , except that there are two fan blades  134  instead of one fan blade  34 , two corresponding hubs instead of one, two sets of bearing assemblies, and two sets of mounting hardware to mount the fan blades  134  to bracket  180 . Except for the length of fan blades  134 , all dimensions of fan blade assembly  130  are the same as the dimensions of fan blade assembly  30 . 
     Fan blade assembly  130  is placed into cooling package  10  by mounting ends of bracket  182  onto frame  80  so that the center of each fan blade  134  of fan blade assembly  130  are generally centered horizontally with respect to upstream of face  24  of radiator  20  and so that one fan blade is generally ⅓of the height of radiator  20  away from the top of frame  80  and one fan blade is generally ⅓of the height of radiator  20  away from the bottom of frame  80 . Clearances between each middle region of fan blades  134  and upstream face  24  of radiator  20  are between about 20 mm and about 30 mm, with a preferred clearance of about 25 mm for the same reasons as stated above. 
     The present invention should not be limited to the above-described embodiments, but should be limited solely by the following claims.