Patent Publication Number: US-2004047734-A1

Title: Ring cooling fan

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a cooling fan, and, more specifically, to an improved ring cooling fan.  
       BACKGROUND OF THE INVENTION  
       [0002] In an internal combustion engine (e.g., a diesel or a gasoline engine), a known or conventional ring cooling fan regulates a temperature of an engine coolant that cools the engine by drawing and/or pushing air through a heat conducting radiator. It is known to use an outer ring to connect a multiplicity of fan blades to one another. FIG. 5 shows an example of the conventional ring cooling fan  100  including multiple fan blades  110  and an outer ring  120 .  
       [0003] As shown in FIG. 5, the outer ring  120  includes a first portion  121  and a second portion  123  connected with the first portion  121 , such that the outer ring  120  has an about L-shaped cross-section. The first portion  121  is in the form of a connecting portion that connects a distal end of each of the fan blades  110 . The second portion  123  is in the form of an external stiffening portion that stiffens the outer ring  120 . It is known to form the conventional ring cooling fan  100  by injecting molten plastic into a mold in an injection molding process. By the use of the external stiffening portion, warpage of the conventional ring cooling fan  100  after removal from the mold and during subsequent cooling is decreased.  
       [0004] Further, the first portion  121  extends an entire length of a corresponding length of each of the fan blades  110  along an axis of rotation of the conventional ring cooling fan  100 , such that the fan blades  110  are completely disposed within a cylinder having a height equal to the length of the first portion  121  along the axis. By the use of such a connecting portion, noise generated by the operation of the conventional ring cooling fan  100  can be decreased.  
       [0005] However, the conventional ring cooling fan  100  suffers from a number of disadvantages associated with the above-discussed structure of the outer ring  120 . Molding of the first portion  121  and of the second portion  123  requires a large amount of plastic material. The use of the large amount of plastic increases costs related to the conventional ring cooling fan  100 . Also, there is increased stress between the fan blades  110  and the outer ring  120  at and/or near the areas and/or volumes of connection therebetween. Finally, having the first portion  121  extend the entire length of the corresponding length of the fan blades  110  impedes air flow through the conventional ring cooling fan  100 .  
       [0006] Thus, an improved ring cooling fan is desired that avoids the above-discussed disadvantages. For example, it is desirable to obtain a ring cooling fan that provides decreased stresses between fan blades and a fan ring. It is also desirable to obtain a ring cooling fan that provides improved air flow. It is further desirable to obtain a ring cooling fan that provides decreased noise during operation.  
       SUMMARY OF THE INVENTION  
       [0007] The present invention provides a ring cooling fan including a fan hub having a top surface and a bottom surface disposed apart from the top surface along an axis of rotation of the ring cooling fan for connection with a drive shaft or a clutch body. A first fan blade including a first distal end and a first proximal end opposite the first distal end is connected with the fan hub. A second fan blade including a second distal end and a second proximal end opposite the second distal end is also connected with the fan hub. A fan ring without an external stiffening portion is connected with the first distal end of the first fan blade and the second distal end of the second fan blade.  
       [0008] The present invention further provides a ring cooling fan including a fan hub having a top surface and a bottom surface disposed apart from the top surface along an axis of rotation of the ring cooling fan for connection with a drive shaft or a clutch body. A first fan blade including a first distal end and a first proximal end opposite the first distal end is connected with the fan hub. A second fan blade including a second distal end and a second proximal end opposite the second distal end is connected with the fan hub. A fan ring that does not include an about L-shaped cross-section is connected with the first distal end and the second distal end.  
       [0009] The present invention further provides a ring cooling fan including a fan hub having a top surface and a bottom surface disposed apart from the top surface along an axis of rotation of the ring cooling fan for connection with a drive shaft or a clutch body. A first fan blade including a first distal end and a first proximal end opposite the first distal end is connected with the fan hub. A second fan blade including a second distal end and a second proximal end opposite the second distal end is also connected with the fan hub. A fan ring is connected with the first distal end and the second distal end. A first winglet is connected between the first fan blade and a first portion of the fan ring. The fan ring can include an about L-shaped cross-section having an external stiffening portion. However, preferably the fan ring does not include such a stiffening portion.  
       [0010] The present invention further provides a process of producing a ring cooling fan including a fan hub, a first fan blade including a first distal end and a first proximal end opposite the first distal end and connected with the fan hub, a second fan blade including a second distal end and a second proximal end opposite the second distal end and connected with the fan hub, and a fan ring connected with the first distal end of the first fan blade and the second distal end of the second fan blade. The process includes disposing the fan hub in a mold, molding the fan ring without an external stiffening portion to the first distal end of the first fan blade and to the second distal end of the second fan blade, and removing the ring cooling fan from the mold.  
       [0011] The present invention further provides a process of producing a ring cooling fan including a fan hub, a first fan blade including a first distal end and a first proximal end opposite the first distal end and connected with the fan hub, a second fan blade including a second distal end and a second proximal end opposite the second distal end and connected with the fan hub, a fan ring connected with the first distal end of the first fan blade and the second distal end of the second fan blade, and a winglet. The process includes disposing the fan hub in a mold, molding the fan ring without an external stiffening portion to the first distal end of the first fan blade and to the second distal end of the second fan blade, and removing the ring cooling fan from the mold.  
       [0012] The present invention further provides a process of producing a ring cooling fan including a fan hub, a first fan blade including a first distal end and a first proximal end opposite the first distal end and connected with the fan hub, a second fan blade including a second distal end and a second proximal end opposite the second distal end and connected with the fan hub, a fan ring connected with the first distal end of the first fan blade and the second distal end of the second fan blade, and a winglet. The process includes disposing the fan hub in a mold, molding the fan ring to the first distal end of the first fan blade and to the second distal end of the second fan blade, and removing the ring cooling fan from the mold.  
       [0013] The present invention further provides a process of installing one or more winglets on a separately produced ring cooling fan. The process includes installing one or more of the winglets on a separately produced ring cooling fan by any suitable manner of attachment.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:  
     [0015]FIG. 1 shows a bottom isometric view of the ring cooling fan of the present invention.  
     [0016]FIG. 2 shows a top view of the ring cooling fan of FIG. 1.  
     [0017]FIG. 3 shows side view of the ring cooling fan of FIG. 1.  
     [0018]FIGS. 4 a  and  4   b  show top and bottom views, respectively, of the ring cooling fan of FIG. 1 including winglets.  
     [0019]FIG. 5 shows a cross-sectional view of a conventional ring cooling fan. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0020] Examples of preferred embodiments of the present invention will now be described with reference to the drawings, wherein like reference numbers throughout the several views identify like elements. FIGS.  1 - 4  show an example of a ring cooling fan according to the present invention.  
     [0021] As exemplified in the drawings, the preferred ring cooling fan  10  includes a fan hub  20 , a plurality (i.e., at least two (2), preferably six (6) or more, and more preferably ten (10) or more) of fan blades  30 , a fan ring  40 , and optionally a plurality of stiffening ribs  50  (each discussed below).  
     [0022] In a broad embodiment, the fan hub  20  couples the fan blades  30  with a drive shaft (not shown) or a clutch body (not shown). By this arrangement, a rotation of the drive shaft or clutch body about an axis of rotation results in a corresponding revolution of the fan blades  30 /ring cooling fan  10 . It is to be understood that although the fan hub  20  and its associated structure shown in the drawing figures exemplify preferred embodiments, the fan hub  20  can include any structure so long as the fan hub  20  couples with the fan blades  30  for rotation about the axis.  
     [0023] As exemplified in the drawings, the fan hub  20  includes a top surface  21  and a bottom surface  23  that is offset from the top surface  21  along the axis of rotation of the fan hub  20 /the ring cooling fan  10  for connection with the drive shaft or the clutch body. Each of the top and bottom surfaces  21 ,  23 , has a generally circular cross section, and includes portions that are disposed on successive parallel planes (i.e., neither of the top and bottom surfaces  21 ,  23 , are required to lie entirely on a single plane). By this arrangement, in a preferred embodiment, the fan hub  20  is generally cup-shaped.  
     [0024] As exemplified in the figures, a plurality of about-circular holes  25  is used to connect the fan hub  20  with the drive shaft or the clutch body. The plurality of about-circular holes  25  is preferably about equally spaced on the fan hub  20 . In a preferred embodiment, the plurality of about-circular holes  25  includes four (4) holes that are disposed about 90 degrees apart. However, it is to be understood that the plurality of about-circular holes  25  can include any number of holes, each being of any size or shape, and can be disposed at a variety of positions on or along the fan hub  20 . It is to be further understood that satisfactory attachment of the fan hub  20  with the drive shaft or the clutch body can be achieved in the absence of the plurality of about-circular holes  25 .  
     [0025] Optionally, the fan hub  20  can include a plurality of radial slots  27 . The radial slots  27  permit dissipation of heat from the clutch body. The plurality of radial slots  27  is about equally spaced on the fan hub  20 . In a preferred embodiment, the plurality of radial slots  27  includes four (4) slots that are disposed about 90 degrees apart. However, it is to be understood that the plurality of radial slots  27  can include any number of holes or slots, each being of any size or shape, and can be disposed at a variety of positions on or along the fan hub  20 .  
     [0026] Optionally, the fan hub  20  can include one or more interface holes (not shown) disposed on an outer diameter thereof. The interface holes can be used for flow through of liquid plastic during an injection molding process of the ring cooling fan  10 . By this arrangement, the fan blades  30  can be secured to the fan hub  20 . In a preferred embodiment, the fan hub  20  includes thirty six (36) such interface holes, each having a diameter of between 11 and 12 mm. However, it is to be understood that any number of interface holes can be used, each being of any size or shape, disposed at a variety of positions on or along the diameter of the fan hub  20 . It is to be further understood that satisfactory attachment of the fan blades  30  with the fan hub  20  can be achieved in the absence of the interface holes on the fan hub  20 .  
     [0027] The fan hub  20  can be of a variety of materials, including plastics and metals. In a preferred embodiment, the fan hub  20  is a metal capable of being disposed in a mold, such that at least a portion of the ring cooling fan  10  can be molded directly thereon. Specifically, the material can be steel, such as 050 YHK hot roll steel, aluminum, or glass filled nylon. However, it is to be understood that the fan hub  20  can be of any material able to substantially permit operation under the desired operating conditions of the ring cooling fan  10 .  
     [0028] In a broad embodiment, the plurality (i.e., at least two) of the fan blades  30  is connected with the fan hub  20 , such that the fan blades  30  effectively cool the engine. As exemplified in the drawings, in a preferred embodiment, the plurality of fan blades  30  includes six (6) or more fan blades  30 , and, more preferably includes ten (10) or more fan blades  30 . It is to be understood that although the fan blades  30  and their associated structure shown in the drawing figures exemplify preferred embodiments, the fan blades  30  can include any structure so long as the fan blades  30  effectively cool the engine.  
     [0029] As exemplified in the drawings, each of the fan blades  30  includes a proximal end  31  that is connected with the hub  20  and a distal end  33  that is disposed apart from the proximal end  31  and connected with the fan ring  40 . Contours and/or pitches of each of a top blade surface  35  and the bottom blade surface  37  are selected based on the desired operating conditions and/or cooling requirements of the ring cooling fan  10 . As exemplified in the figures, at least two, and preferably, all of the distal ends  33  of the fan blades  30  are connected to each other via the fan ring  40  (discussed below). Each of the fan blades  30  includes a leading edge  38  adjacent to the top surface  21  of the fan hub  20 , and a trailing edge  39  that is opposite the leading edge  38  and adjacent to the bottom surface  23  of the fan hub  20 .  
     [0030] In a broad embodiment, the fan ring  40  does not include an external stiffening portion or portions (e.g., does not include an about L-shaped cross-section having a stiffening flange) and is connected with at least two of the fan blades  30 . By this arrangement, stress between the fan blades  30  and the fan ring  40  at and/or near an area and/or volume of attachment therebetween can be decreased. Further, the amount of material required to mold the ring cooling fan  10  can be decreased, thereby decreasing the cost of material. Although the drawings show preferred embodiments of the fan ring  40 , it is to be understood that the fan ring  40  can be of any cross-sectional shape, and can connect any of a plurality of the fan blades  30  at any location along the length of the fan blades  30 , so long as the fan ring  40  does not include an external stiffening portion or portions.  
     [0031] As exemplified in the drawings, a preferred embodiment of the fan ring  40  has an about rectangular cross-section, and more preferably, has an about rectangular cross-section that is an about trapezoidal cross-section including one or more draft surfaces to facilitate removal of the ring cooling fan  10  from a mold during the injection molding process.  
     [0032] The fan ring  40  includes a top edge  41  and a bottom edge  43  opposite the top edge  41 . In a preferred embodiment, as exemplified in the drawings, the fan ring  40  has a length between the top and bottom edges  41 ,  43 , that is less than a corresponding length of one or more of the fan blades  30  along the axis of rotation of the ring cooling fan  10 . The top edge  41  of the fan ring  40  is disposed at an elevation about the same as that of the leading edge  38  of one or more of the fan blades  30 , such that the bottom edge  43  of the fan ring  40  is disposed at an elevation between (i) the leading edge  38  of one or more of the fan blades  30  and (ii) the trailing edge  39  of one or more of the fan blades  30 . By this arrangement, an optimum position of the fan blades  30  within the fan ring  40  can be achieved, such that air flow through the ring cooling fan  10  is maximized and/or is not impeded unnecessarily by the fan ring  40 .  
     [0033] However, it is to be understood that the top and bottom edges  41 ,  43 , of the fan ring  40  can be disposed at any elevations relative to the leading and trailing edges  38 ,  39 , of any of the fan blades  30 , and that the length of the fan ring  40  between the top and bottom edges  41 ,  43 , can be greater than, less than, or equal to the corresponding length of one or more of the fan blades  30  along the axis of rotation of the ring cooling fan  10 . For example, the fan ring  40  can have a length that is about equal to a corresponding length of the fan blades  30  along the axis of rotation of the ring cooling fan  10 . Further, the top edge  41  of the fan ring  40  can be disposed at an elevation that is different than that of the leading edge  38  of one or more of the fan blades  30 , and the bottom edge  43  of the fan ring  40  can be disposed at an elevation different than that of the trailing edge  39  of one or more of the fan blades  30 . As another example, the top edge  41  of the fan ring  40  can be disposed at an elevation about the same as that of the leading edge  38  of one or more of the fan blades  30 , and the bottom edge  41  of the fan ring  40  can be disposed at an elevation about the same as that of the trailing edge  39  of one or more of the fan blades  30 .  
     [0034] The ring cooling fan  10  can include one or more of the winglets  60  to attach a portion of the one or more of the fan blades  30  to one or more portions of the fan ring  40 . Preferably, the ring cooling fan  10  includes a plurality of winglets  60 , and more preferably, includes the same number of winglets  60  as the number of the fan blades  30  included in the ring cooling fan  10 . As exemplified in the drawings, in a preferred embodiment, the winglet  60  is connected between a length of the fan blade  30  and the fan ring  40 . Preferably, the winglet  60  is connected between the trailing edge  39  of the fan blade  30  and a portion of the fan ring  40 , and more preferably is connected between an edge of the distal end  33  of the fan blade  30  and a portion of the bottom edge  43  of the fan ring  40 . By this arrangement, stress at and/or near the area and/or volume of connection between the fan blades  30  and the fan ring  40  can be distributed over a larger area and/or volume, thereby decreasing stress concentration at the area and/or volume or connection. Further, it is believed that the use of the winglets  60  can increase air flow through the ring cooling fan  10 , and/or can decrease operating noise resulting from the use of fan ring  40  where the top and bottom edges  41 ,  43 , of the fan ring  40  are not disposed at an elevation which is about the same as that of the leading and trailing edges  38 ,  39 , respectively, of one or more of the fan blades  30 .  
     [0035] In a preferred embodiment, as exemplified in the drawings, the winglets  60  are about triangular in shape. The winglets  60  can be molded in an injection molding operation with other components of the ring cooling fan  10  (e.g., the fan blades  30 , the fan ring  40 , etc.). Alternatively, the winglets  60  can be produced as components that are separate from one or more of the other components of the ring cooling fan  10  and attached to the ring cooling fan  10  after the molding process. Thus, it is to be further understood that the winglets  60  can be connected with the ring cooling fan  10  by any method of attachment.  
     [0036] Although the drawings show preferred embodiments of the winglets  60  in a ring cooling fan  10  having a fan ring  40  without an external stiffening portion, it is to be understood that the winglets  60  can be used in any ring cooling fan assembly, including known and/or conventional structures, to provide the above-discussed advantages. For example, the winglets  60  can be used in a known ring cooling fan that includes a fan ring with an about L-shaped cross-section and/or having an external stiffening portion.  
     [0037] In a broad embodiment, the stiffening ribs  50  are optionally disposed on one or more of the top and bottom surfaces  35 ,  37 , of one or more of the fan blades  30 , to decrease warpage and/or catastrophic failure or “bursting” during operation at increased revolution rate of the fan blades  30 . As exemplified in the drawings, in a preferred embodiment, the stiffening ribs  50  are used on both top and bottom surfaces  35 ,  37 , of the ring cooling fan  10 . However, it is to be understood that the stiffening ribs  50  can be used on either, both, or neither of the sides of the fan blades  30 . Further, the heights, number, size, shape, spacing, orientation, and material of the stiffening ribs  50  can be selected such that the desired characteristics of the ring cooling fan  10  are achieved. The open- and closed-box structures of the stiffening ribs  50  are discussed in copending application Ser. No. 10/196,268, filed Jul. 17, 2002, the disclosure of which is incorporated by reference herein in its entirety.  
     [0038] As discussed above, the ring cooling fan  10  is preferably manufactured by an injection molding process. The process can include disposing the fan hub in a mold, molding the fan ring without an external stiffening portion to the first and distal end of the first fan blade and to the second distal end of the second fan blade, and removing the ring cooling fan from the mold. The ring cooling fan can optionally include one or more winglets molded or produced thereon. Alternatively, the process can include installing one or more of the winglets on the ring cooling fan after it is separately molded or produced.  
     [0039] In another embodiment, one or more of the winglets can be installed on a ring cooling fan including a fan ring that has an L-shaped cross-section. This process includes disposing the fan hub in a mold, molding the fan ring to the first distal end of the first fan blade and to the second distal end of the second fan blade, and removing the ring cooling fan from the mold. The ring cooling fan can include one or more winglets molded or produced thereon. Alternately, the process can include installing one or more of the winglets on the ring cooling fan after it is separately molded or produced.  
     [0040] Numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.