Abstract:
A fan shroud ring comprises a first member formed from a polymeric material and configured to be affixed to an internal combustion engine. The first member defines a central opening configured to have a fan associated with the engine project therethrough. The shroud ring includes a second member fabricated from an elastomeric material. The second member is bonded to the first member and encompasses at least a portion of the periphery of the first member. The elastomeric material may include a number of notches formed along its circumference. The notches allow for the flexing of the elastomeric material and thereby enhance the seal between the shroud ring and other components of a cooling system. The shroud ring may include integral stator blades for directing airflow and may also include mounting blocks and associated hardware. The fan shroud ring may be fabricated by an injection molding process.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority of U.S. Provisional Patent Application Ser. No. 60/821,148 filed Aug. 2, 2006, and entitled “Fan Shroud Ring and Method for Its Manufacture.” 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to molded articles. More specifically, the invention relates to molded articles fabricated from a plurality of distinct materials, and to methods for their manufacture. Most particularly, the invention relates to a fan shroud ring intended for use as a component of an internal combustion engine.  
       BACKGROUND OF THE INVENTION  
       [0003]     Internal combustion engines, such as those used to power motor vehicles, generally require a cooling system for removing excess heat from the engine. Typically, the cooling system includes a radiator which circulates a coolant fluid through the engine, and a fan which directs an airflow through the radiator to enhance the cooling. Efficiency of the cooling process is important, particularly in applications involving high power engines such as diesel engines. In some instances, the cooling system includes a fan shroud which functions to encircle the cooling fan and more efficiently direct a stream of cool air across the radiator. In general, it is desirable that the fan and fan shroud be in close engagement so that air is efficiently directed through the radiator; and in this regard, the fan shroud often includes a ring member which functions to seal the space between the fan shroud and the fan. Problems can occur when engine torque or other extraneous forces displace the fan relative to the shroud and/or ring. Such displacement can cause the fan to strike either of these components causing damage.  
         [0004]     As will be explained in detail hereinbelow, the present invention provides a fan shroud ring which is directly affixed to the engine, along with the fan, and as a consequence moves therewith thus preventing inadvertent contact between the fan and shroud components. Furthermore, the shroud ring of the present invention includes an integral elastomeric seal which provides for a tight connection between the shroud ring and the shroud thereby enhancing the efficiency of the cooling system. The fan shroud ring of the present invention is a composite member fabricated from a first, relatively rigid material, and a second, elastomeric material. As will be explained in detail hereinbelow, the present invention further provides a novel configuration for the components of the shroud ring, and further includes specific formulations of materials both of which will enhance the integrity of the device. The present invention also includes a novel method for the manufacture of the multi-component structure. These and other advantages of the invention will be apparent from the drawings and discussion which follow.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0005]     Disclosed herein is a shroud ring for a fan of an internal combustion engine. The ring comprises a first member formed from a polymeric material. The first member is configured to be affixed to an internal combustion engine and defines a central opening configured to have a fan associated with said engine project therethrough. The shroud ring further includes a second member fabricated from an elastomeric material. The second member is bonded to the first member and encompasses at least a portion of the periphery of the first member. The first member may, in particular embodiments, further define a plurality of stator ribs extending from the central opening to the periphery thereof. The stator ribs are operable to direct a flow of air passing thereacross. In particular instances, the elastomeric second member may encircle substantially all of the perimeter of the first member, and in particular embodiments may include one or more notches therein which extend from a free perimeter edge of the second member into the body thereof. The elastomeric material may be joined to the material of the first member by a stepped joint which functions to increase the contact area therebetween. Bonding agents may be used to enhance the bond between the two materials. In some instances, the elastomeric material may include a relatively small amount of either the first material or a material having similar physical properties. Inclusion of this material can enhance bonding. In specific instances, the polymeric material of the first member is nylon or polypropylene and may include a reinforcing material therein. The elastomeric material may comprise a synthetic rubber in particular instances.  
         [0006]     In some instances, the fan shroud ring may be fabricated by an injection molding process wherein a first portion of the ring is molded in a first step of the molding process, and a second portion of the ring is molded thereonto in a second injection process. In a particular instance, the shroud ring can be fabricated in the molding apparatus which includes a mold cavity which defines the shroud ring. The molding apparatus further includes a movable blade member which can be positioned in the cavity so as to define a first portion of the cavity which corresponds to a first portion of the fan shroud ring. A polymeric material is injected into the first portion of the cavity, and thereafter the blade is displaced so as to expose a surface of the previously molded first portion. A second polymeric material is injected into the remaining portion of the cavity and forms a bond with the first polymeric material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a perspective view of one embodiment of fan shroud ring in accord with the principles of the present invention;  
         [0008]      FIG. 2A  is a top plan view of the fan shroud ring of  FIG. 1 ;  
         [0009]      FIG. 2B  is a cross-sectional view of the fan shroud ring of  FIG. 2A  taken along line A-A;  
         [0010]      FIG. 3A  is an enlarged, cross-sectional view of a portion of the fan shroud ring of  FIG. 2A  better illustrating the junction between the elastomeric material and rigid thermoplastic material;  
         [0011]      FIG. 3B  is an enlarged view of the shroud ring of  FIG. 2A  illustrating the stator structure thereof;  
         [0012]      FIG. 4A  is an enlarged view of a portion of the shroud ring of  FIG. 2A  showing the elastomeric member and notch structure;  
         [0013]      FIG. 4B  is an enlarged view of a portion of the shroud ring of  FIG. 2A  showing the mounting block; and  
         [0014]      FIG. 5  is a perspective view of one particular embodiment of blade structure including integral cam surface, which blade may be utilized in an injecting molding process for the fabrication of the fan shroud ring.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     The fan shroud ring of the present invention may be variously configured, and for purposes of illustration, one specific embodiment will be discussed. Referring now to  FIG. 17  there is shown a fan shroud ring  10  in accord with the present invention. As shown, the ring  10  is a composite member having a first portion  12  formed from a relatively rigid material, which is typically a polymeric material. Such materials include high strength polymers, and one particular group of such high strength polymers comprises nylons. Polypropylene is another specific material which may be used in this invention. As is known in the art, the polymer material may include a reinforcing filler in the form of fibers, particles or the like. Such fillers can include glass, mica, carbon, other minerals, as well as polymeric materials. Mica-filled polypropylene is employed in specific high-temperature applications.  
         [0016]     The shroud ring  10  further includes an elastomeric sealing portion  14  integrally bonded to the rigid portion  12 . The sealing portion  14  forms an outer radius of the ring, and in use serves to engage further portions of the shroud assembly and provide a relatively tight gasket seal thereagainst. The elastameric portion  14  may be fabricated from synthetic or natural rubbers, as well as from other polymeric materials having sufficient resiliency and strength. One particular material having utility for the fabrication of the resilient portion  14  comprises a synthetic rubber sold by the Exxon Corporation under the designation Santoprene. As will be described in detail hereinbelow, the resilient material may be specifically formulated to provide good compatibility with the material comprising the rigid portion  12 .  
         [0017]     In use shroud ring  10  is fixedly mounted to the engine of a motor vehicle, and in this regard includes mounting blocks  16   a ,  16   b ,  16   c , it being understood that a smaller or larger number of mounting blocks may be employed in other applications. Typically, the ring  10  is mounted onto the motor vehicle via bolts or other such fasteners which pass through the mounting blocks  16 . Gaskets, seals, vibration-damping members or the like may be used in connection with the mounting; however, it is a notable feature of the present invention that such members need not be included, and the ring  10  is capable of being directly mounted onto the engine. The ring  10  is disposed so that the fan of the motor vehicle projects through the central opening  18  of the ring. The elastomeric portion  14  of the ring  10  contacts the remainder of the engine cooling shroud assembly and establishes a relatively airtight seal therebetween. It is another notable feature of the present invention that this resilient portion  14  includes a plurality of notches, such as notch  20  formed along the periphery thereof. These notches accommodate flexing and bending of the resilient member and enhance the integrity of the resultant seal. Since the shroud ring  10  is affixed to the vehicle&#39;s engine, displacement of the engine resultant from torque will move the shroud ring along with the engine and fan. The resilient portion  14  will serve to maintain contact with the remainder of the shroud assembly, despite the displacement of the fan, and the notches  20  will maintain the integrity of the seal. Also, the unitary motion of the ring and fan will prevent the fan from striking the ring, as is the case with prior art shroud assemblies.  
         [0018]     Referring now to  FIG. 2A , there is shown a top plan view of the shroud ring  10  of  FIG. 1 .  FIG. 2B  is a cross-sectional view of the shroud ring  10  of  FIG. 2A , taken along line A-A. Visible in both figures is the rigid portion  12 , the resilient portion  14 , the mounting blocks  16 , and the notches  20 , all as discussed above.  
         [0019]     Referring now to  FIGS. 3A and 3B , there are shown details C from  FIG. 2A . These details comprise enlarged views of portions of the shroud ring  10 .  FIG. 3A  is a cross-sectional view of a portion of the shroud ring of  FIG. 2 , and shows the junction between a sidewall segment of the rigid portion  12  and the resilient portion  14  of the shroud ring. As will be seen, the joint therebetween has a stepped configuration such that a portion of the resilient material  14  projects into a corresponding notch  15  in the rigid sidewall portion. This stepped structure increases the surface area between the two components and thereby enhances the integrity of the seal.  
         [0020]     In specific instances, the materials comprising the rigid and resilient portions are selected to maximize compatibility between the two materials. For example, in one particular embodiment, the rigid portion is fabricated from a nylon polymer, and the resilient portion is fabricated from a thermoplastic elastomer (TPE) such as Santoprene sold by the Exxon Corporation. In accord with the present invention, it has been found that adhesion between the two materials, and hence the integrity of the seal, is enhanced in some instances if the thermoplastic elastomer is alloyed with a small amount of nylon, typically ranging up to 10%. Another material having physical properties similar to at least some of those of the nylon may be used in a similar manner to enhance bonding.  
         [0021]      FIG. 3B  is an enlarged view of the shroud ring of  FIG. 2A  and shows a segment of the resilient portion  14 , better illustrating the notch  20 . Also shown is a segment of the rigid portion specifically illustrating a stator rib, or fin,  22 . As will be better seen in  FIG. 2A , the shroud ring includes a plurality of such stator ribs, and these ribs may be angled to provide for direction of airflow through the shroud ring. They also provide structural rigidity to the unit.  
         [0022]      FIGS. 4A and 4B  show enlarged portions of the shroud ring of  FIG. 2A . Specifically,  FIG. 4A  provides an enlarged view of one of the notches  20  in the resilient portion  14 . As noted, this notch reduces kinking and thereby accommodates flexing and bending of the resilient body when the shroud ring is engaged with the remainder of the shroud assembly.  FIG. 4B  is an enlarged view of one of the mounting blocks  16   b . As will be seen, the block is configured to accommodate a mounting bolt or other such hardware.  
         [0023]     The shroud ring of the present invention may be fabricated through a variety of processes. One specific group of fabrication techniques comprises injection molding. In one instance, a two-shot injection molding process may be used to fabricate the shroud ring. In a process of this type, a first portion of the shroud ring, such as the rigid portion, is formed by injection of a first polymeric material into a molding system; and thereafter, the second portion, for example the elastomeric portion, is then molded onto the first by injecting the second material into the molding apparatus so that this material contacts the first portion which was previously molded, and bonds thereto. There are a number of techniques for implementing such two-shot molding processes. In one method in accord with the present invention, the first material is molded into a mold cavity, which cavity includes a movable blade member which can, in a first position, be disposed so as to occlude a portion of the mold cavity thereby restricting the injected first body of material to a first area of the cavity. Following this first injection, the movable member is displaced so as to open a second portion of the mold cavity, which portion is configured to receive the second injected polymeric material. Referring back to  FIG. 3A , it is to be noted that the notch  15  in the rigid portion  12  defining the stepped joint may, in one molding process, be defined by a displaceable ring member which, in its first position, configures the notch. This ring is subsequently displaced in a downward direction relative to  FIG. 3  so as to allow access of the elastomeric material comprising the second portion  14 . It will be noted from  FIG. 3  that the underside of the second portion  14  includes a slight notch, and this is an artifact of the presence of the displaceable blade.  
         [0024]     In one particular embodiment of apparatus used for a two-shot molding process for the fabrication of the aforedescribed shroud ring, the molding apparatus includes a retractable, ring-shaped blade having an upper surface which provides the aforedescribed occluding function and a lower surface which is a camming surface. By use of an appropriate cam linkage, it will be understood that this ring may be reciprocated in an upward and downward direction so as to accommodate the molding process.  FIG. 5  is a perspective view of the aforedescribed blade structure  30 .  
         [0025]     The structures of the present invention may be prepared by other processes. Such processes may include transfer molding wherein a first portion of the component is manufactured in a first molding station and then transferred to a second molding station wherein the second portion is molded thereonto. These molding stations may be in a single apparatus or in separated apparatus. Another method could comprise rotational molding wherein a molding apparatus rotates between separate stations wherein portions of the component are molded thereonto. In yet other instances, components may be assembled via adhesives, ultrasonic welding, thermal bonding or the like to prepare the composite structure. All of such embodiments are within the scope of this invention.  
         [0026]     In view of the foregoing, it is to be understood that numerous modifications and variations of the present invention may be implemented by those of skill in the art. In that regard, the shroud ring assembly may include further portions formed from rigid or elastomeric material thereupon. Likewise, the overall size or shape of the ring may be varied to accommodate particular applications. Likewise, fabrication processes other than those specifically disclosed herein may be readily implemented by those of skill in the art. Therefore, it is to be understood that the foregoing drawings, discussion and description are illustrative of specific embodiments of the invention, but are not meant to be limitations upon the practice thereof. It is the following claims, including all equivalents, which define the scope of the invention.