Abstract:
Disclosed is a method of locating and holding one or more sheets of air permeable media within an injection mold tool and holding the location until the mold tool engaged and holds media sheets, as well as molding a support frames encapsulating the media sheets to form a unitary encapsulated filtration product.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/073,985, filed Nov. 1, 2014. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to a method of positioning and holding one or more stacked sheets of air permeable media or filtration media within a molding tool prior, continuing to hold the media in place during encapsulation with a plastic resin, thereby reliably positioning and encapsulating the media in an efficient means into a molded frame formed directly onto the media, forming a unitary encapsulated product. Also disclosed is a hydrocarbon adsorption trap manufactured by this method. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the art it is known to provide a frame to mount a filter media in a housing and to support the filter media. It is also known to produce a filtration device by separately producing a frame member configured to receive the media and then gluing filter media into the frame member to form the intended filter element or device product. 
         [0004]    It is known to produce air permeable media sheets have open pores sized to capture or restrict the passage of particle or contaminants for filtering fluids or as well as using air permeable sheets to enclose hydrocarbon adsorption media having hydrocarbon adsorption properties. 
         [0005]    Regarding hydrocarbon adsorption media and HCA traps, it is desirable to trap evaporated fuel and oil vapors within the air intake system, thereby preventing their release into the outside environment. Fuel vapors contain hydrocarbons which are known to be a significant contributing component in urban smog. 
         [0006]    Gasoline, for example, is a highly volatile hydrocarbon fuel that includes components which transition easily from a liquid to vapor phase. Elevated temperatures such as occurring during normal internal combustion engine operation accelerate the liquid to vapor transition. The hydrocarbon vapors, unless treated or captured, may ultimately discharge into the atmosphere. It is known that hydrocarbon vapors are discharged from the engine crankcase during engine operation. When the engine is shutdown, these vapors may continue to be released from the hot engine crankcase and other components, particularly as the engine cools. 
         [0007]    The control of hydrocarbon vapors escaping into the environment is regulated by state and federal regulations. Hydrocarbon traps for capturing hydrocarbon vapors are well known. For example, motor vehicles are commonly equipped with hydrocarbon adsorptive emissions canisters connected to the fuel tank for trapping hydrocarbon vapors, particularly as emitted during refueling. 
         [0008]    It is known that certain porous materials such as activated carbon are useful for absorption and removal of organic hydrocarbon vapors. It is known hydrocarbon vapors are liquefied within small micro pores of the activated carbon and may be retained by absorption. 
         [0009]    It is known in the state of the art to produce a hydrocarbon adsorption (HCA) media, such as two adjacent sheets of air permeable media between which hydrocarbon adsorptive materials are arranged. It is known to arrange such HCA media in an air intake system of an internal combustion engine where it is operable to entrap hydrocarbon vapors. 
         [0010]    As a general introduction to the art of injection molding-injection molding is a manufacturing process for producing parts by injecting thermoplastic, thermosetting polymers, plastic or resin materials into a mold tool. Common polymers like epoxy and phenolic are some examples of thermosetting plastics while nylon, polyethylene, and polystyrene are examples of thermoplastic materials. 
         [0011]    Injection molding machines generally consist of a material hopper, an injection ram or screw-type plunger, and a heating unit. Also known as presses, they hold the molds in which the final components are shaped. Presses are typically rated by tonnage, which expresses the amount of clamping force that the machine can exert. This force keeps the mold closed during the injection process, which may involve high pressures in the plastic injection process to completely fill the mold cavity. 
         [0012]    The mold may consist of two primary mold halves, the injection mold plate and the ejector mold plate. Plastic resin may enter the mold through a sprue or gate in the injection mold; the sprue bushing is to seal tightly against the nozzle of the injection barrel of the molding machine and to guide/direct molten plastic to flow from the barrel into the mold, also known as the mold cavity. The sprue bushing directs the molten plastic to the cavity through channels that are machined into the faces of the mold plates. These channels allow plastic to run along them. The channels may also be called runners. The molten plastic flows through the runners and into the cavity geometry to form the desired part. 
         [0013]    Typically in the state of art, the material for the part is fed into a heated barrel, mixed, and forced into a mold cavity, where it cools and hardens to the configuration of the cavity, thereby forming the desired part or component. The mold with the cavity is often shaped and designed from metal, typically either steel or aluminum, and precision-machined to form the features of the part to be molded. 
         [0014]    The mold closes enclosing the mold cavity therein. When parts are molded, typically pelletized raw material may be fed through a hopper into a heated barrel with a reciprocating screw. The material is forced at high pressure into the part forming mold cavity. Once the material within the mold cools so that the molded part is dimensionally stable, the mold opens and the molded dimensionally stable part may be removed from the mold and the process restarted. 
       SUMMARY OF THE INVENTION 
       [0015]    An object of the invention is to provide a method and apparatus to accurately position one or more sheets (stacked sheets) of an air permeable media, such as a filtration media, within a mold tool and to provide a retractable media location enforcement means within the mold tool to locate the media and hold the location of the media at a desired location within the tool, as well as second media holding means operable to engage and continue to hold the media in the position within the mold after the retractable location enforcement means are retracted, and continue holding during the plastic resin encapsulation process. 
         [0016]    According to the present inventive disclosure, an innovative injection molding process is advantageously utilized to manufacture filter elements or hydrocarbon adsorption traps, such as the exemplary types and configurations disclosed herein. Advantageously, the present inventive disclosure discloses method of positioning/fixing location and loosely stacking filter media sheets or HCA media sheets in a mold tool, wherein the tool includes locating components operable to fix the location of the media within the mold tool to a desired position during media loading into the tool, closing of the tool and subsequent injection molding. Advantageously, the present inventive disclosure teaches methods of locating and molding a frame around the periphery of the media sheets, holding the media sheets in the mold tools while automatically retracting media positioning/locating components before molding, and then molding the frame around the periphery media sheets to form the desired filter product or HCA trap as a single, one-piece, integrally molded component. 
         [0017]    Advantageously in the invention, the present methods located the media within the mold and maintain the required position before and during frame molding, advantageously deleting other secondary steps practiced in the art including gluing the media and further producing a separate frame component and then assembling the frame to the glued media. As such, the specially modified injection molding process disclosed herein is advantageously utilized to manufacture filter elements or hydrocarbon adsorption traps in an automated, efficient, repeatable, reliable and low cost way, while eliminating additional steps of the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
           [0019]    Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings. 
           [0020]      FIG. 1  depicts a perspective view of an encapsulated filter device of filtration media manufactured by the methods disclosed herein, for example, a hydrocarbon adsorption trap or for use as a filter device for filtering a fluid; 
           [0021]      FIG. 2  depicts a perspective view of hydrocarbon adsorption media sheets, skewed for easy visibility, cut to size for insertion into the molding tool and encapsulation into the support frame, consistent with the present invention and according to an exemplary embodiment discussed and illustrated herein for the understanding of the reader; 
           [0022]      FIG. 3  depict a cross-section of a portion of a hydrocarbon adsorption media sheet, such as in  FIG. 2 , consistent with the present invention; 
           [0023]      FIG. 4A  depicts a schematic side view of press and tool in the open position, including the mold halves and additional components to realize the innovative method of manufacturing an encapsulated filter device or a hydrocarbon adsorption trap, consistent with the present invention; 
           [0024]      FIG. 4B  depicts a schematic side view of press and tool in the closed open position, consistent with the present invention; 
           [0025]      FIG. 5  depicts a schematic top view of a mold plate showing the media sheet(s) held in position along their circumferential edges by contact with temporarily raised position holding pins, consistent with the present invention; 
           [0026]      FIG. 6 . depicts a schematic cross section of upper and lower mold tool plates in a closed position, holding the media sheets in place with the temporarily raised position holding pins retracted, consistent with the present invention; 
           [0027]      FIG. 7 . is a top view of a first mold plate (mold tool half) showing the position holding pins spaced radially outwardly from the raised compression rim of the media fixation wall, and channels (or runners) through which resin or moldable material is delivered into the mold cavity, consistent with the present invention; and 
           [0028]      FIG. 8 . is a top view of a mating second mold plate (mold tool half) showing channels through which resin or moldable material is delivered to the cavity, and springs compressively loading the inner mold tool portion, consistent with the present invention. 
       
    
    
       [0029]    Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
       DETAILED DESCRIPTION 
       [0030]    Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of apparatus components related to a filter apparatus. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
         [0031]    In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
         [0032]    In one exemplary embodiment for enablement and illustration of the disclosed method of producing an encapsulated filter device of one or more sheet of air permeable filtration media,  FIG. 3  depicts a portion of a hydrocarbon adsorption (HCA) media sheet  12  such as envisioned for use in the method disclosed herein to product a unitary over molded HCA trap. It is to be understood that the disclosed method is not limited to HCA media and production of HCA traps, but is instead also intended for production of filter elements or device, for example, air filter elements. Specifically the same methods may be used to produce plastic encapsulated flow-through filter devices adapted for filtration of gaseous or liquid fluids. For brevity, the present method and product characteristics are taught herein by example/illustration with reference to an preferred embodiment of an HCA trap. 
         [0033]    In the exemplary embodiment of the HCA trap, the HCA media sheet  12  may include a first hydrocarbon vapor permeable media retention layer  16 , a second hydrocarbon vapor permeable media retention layer  18  preferably positioned in a spaced parallel relationship to the first layer forming a gap  22  therebetween and a hydrocarbon vapor adsorbent media  20  disposed in the gap  22  between the first  16  and second  18  layers for adsorbing hydrocarbon laden vapors, for example evaporated fuel vapors from the intake tract when the engine is not operating. 
         [0034]    In some embodiments of the HCA media sheet  12 , the spaced media retention layers  16  and  18  may be secured together or closed/joined together along the periphery edge  74  of the media sheet  12  to seal the gap  22  at the layer edge portions  74  to retain the adsorbent media  20  between the layers  16  and  18 , thereby preventing the hydrocarbon vapor adsorbent media  20  from escaping the gap  22  between the media retention layers  16  and  18 . 
         [0035]    In a preferred embodiment of the HCA media sheet  12 , the edge portions of the spaced media retention layers  16  and  18  may be remain open, then relying upon the modified injection molding process of the present invention to seal the seal the edge portions of the spaced media retention layers  16  and  18  with the injection molded support frame  14 , thereby preventing the hydrocarbon vapor adsorbent media  20  from escaping the gap  22  between the media retention layers  16  and  18 . 
         [0036]    In another preferred embodiment of the HCA media sheet  12 , the edge portions of the spaced media retention layers  16  and  18  may be open with the hydrocarbon vapor adsorbent media  20  secured in the gap  22  between the media retention layers  16  and  18  with an adhesive material  24 , thereby holding the hydrocarbon vapor adsorbent media  20  within the gap  22  at least until finally sealed within by the injection molded support frame  14  molded onto the peripheral edges of the HCA media sheet  12 . The media retention layers with the adhesive bound hydrocarbon vapor adsorbent media may form a substantially rigid flat sheet, the substantially rigid sheet having sufficient rigidity to be self supporting, maintaining the sheet in a flat sheet form when supported only at the peripheral circumferential edges of the sheet. 
         [0037]    The hydrocarbon adsorbent media  20  is preferably a hydrocarbon absorptive material, examples of which include activated carbon, zeolite, or other known hydrocarbon vapor absorptive materials. 
         [0038]    In preferred aspects of the HCA media sheet  12 , the hydrocarbon adsorbent media  20  includes activated carbon granules. 
         [0039]    In preferred aspects of the HCA media sheet  12 , the hydrocarbon adsorbent granules  20  may be bound together by an adhesive  24 , the adhesive  24  maintaining the granules  20  in a desired spaced distribution between the spaced media retention layers  16  and  18  and optionally in a preferred shape or form (such as in a sheet form  12  of substantially uniform thickness (substantially uniform spacing between the spaced media retention layers  16  and  18 ). 
         [0040]    The hydrocarbon vapor permeable layers (or air permeable layers)  16  and/or  18  may be realized as woven or non-woven synthetic fiber layers, for example polyester fiber layers. In some embodiments the air permeable layers  16  and/or  18  may be realized as synthetic nonwoven fiber sheets. Nonwoven fabrics may be manufactured, in multiple forms, from many grades of cellulose and most natural and synthetic fibers. Fibers used may include polyester, polypropylene, glass, acrylics, rayon, nylon, cotton, fluoropolymers and a host of others fiber materials select due to their special material compatibility for particular applications, such as selection for heat, hydrocarbon and fuel vapor exposure compatibility. 
         [0041]    As shown in  FIG. 2 , embodiments of the over molded filter media product or a HCA trap  10  may include multiple stacked and overlaid filter media sheets  12  (or for example, HCA media sheets), such as the flat substantially rigid HCA media sheets  12  in  FIGS. 1 and 2 . The media sheets  12  are air permeable and may be fuel vapor permeable and therefore permit (in the case of a HCA trap) parallel stacking of the media sheets  12  onto each other to provide a desired hydrocarbon adsorption capacity for the HCA trap  10 . The parallel stacked media sheets  12  are illustrated in  FIG. 2  as skewed spatially only to better illustrate the stacking of preferably identically shaped and sized HCA media sheets  12 , the stacking of sheets to form an HCA trap of sufficient hydrocarbon adsorption capacity. Although preferred for molding, the media sheets  12  are not required to be identically shaped or sized and may differ in length, width or shape. The media sheets  12  have peripheral circumferential edges  74  which will be encapsulated into the mold plastic peripheral support frame  14  according to the present invention. 
         [0042]    Showing the process by example,  FIG. 1  shows one embodiment of a filtration device  10 , for one example the exemplary molded hydrocarbon adsorption trap (HCA trap)  10  manufactured by the process described herein. In the embodiment illustrated, the HCA trap includes one or more hydrocarbon adsorption media sheets  12  (see  FIG. 2 ) which may be aligned and stacked directly one on top of the other in a mold tool, and then encapsulated along the periphery of the media sheets  12 , embedding the media sheets  12  into a peripheral support frame  14 . In some embodiments, the formed peripheral support frame  14  is substantially rigid so as to be self-supporting and providing support to the hydrocarbon adsorption media sheets  12  while in use, say, for example, within an air intake tract of an internal combustion engine. In other embodiments, the peripheral support frame  14  may be flexible, such as made of a deflectable, possibly stretchable elastomeric material, the flexibility permitting the support frame to bend and conform to the available interior space and configuration of a housing in which the support frame is to be mounted. The peripheral support frame may have one or more radial projection portions  72  of plastic material filled into the space left by the retracting media position holding pins  34  when the retract into the mold. The compressed media region  70  is the region compressed by the media fixation walls  56 , discussed later. 
         [0043]    The peripheral support frame  14  provides support to the filter media sheet(s) or (for example) hydrocarbon adsorption media sheets  12 , at least along the peripheral edges of the sheets, to mount the hydrocarbon adsorption media sheet or sheets  12  onto, for example, an insides surface of an air duct, or an air intake tract, or into the interior of a filter housing, although the hydrocarbon adsorption trap according to this disclosure may be installed to other components or used in other applications. 
         [0044]    In the exemplary embodiment illustrated in  FIG. 1 , the media sheets  12  are substantially flat/planar and permanently embedded at their periphery by injection molding into the peripheral support frame  14 . The peripheral support frame  14 , as in  FIG. 1 , may have one or more mounting tabs  26  formed with the frame  14  during the molding and projecting outwardly away from the support frame  14 . One or more of the tabs  14  may include through holes, such as mounting holes  28 , configured to receive fasteners (not shown) or other fastening means (for example, heat stakes) to enable mounting of the support frame to another component. 
         [0045]      FIG. 4A  depicts a schematic side view of press  30  in the open position with the tool including the mold tool halves  36  and  38  and additional components to realize the innovative method of manufacturing a hydrocarbon adsorption trap, as disclosed herein.  FIG. 4B  depicts a schematic side view of press  30  in the nearly closed position. As the press  30  moves to close, the media sheets  12  are eventually compressed and held in position by the media fixation walls  56 , discussed later. The mold tool halves  36  and  38  are preferably made of metals such as suitable varieties of steel, hardened or tool steel, or aluminum. 
         [0046]    In  FIG. 4A  the press  30  is shown in an open position. For injection molding, the upper press portion  42  moves in direction  48  to a closed position ( FIG. 4B ), the upper press portion  42  closing onto and compresses against the lower press portion  44  to close the mold cavity  46  (see  FIGS. 6 and 7 ) therebetween prior to injection of thermoplastics or resins into the mold cavity  46  for forming the peripheral support frame  14  and embedding the hydrocarbon adsorption sheets into the peripheral support frame  14 . Advantageously and according to the invention, either one or both of the mold tool halves  36  and  38  may include tool compression springs  40  (schematically shown) operable to transmit compressive forces F 1 , F 2  from the press  30  onto the mold tool halves  36  and  38  to hold the mold tool halves  36  and  38  fully compressively closed against and onto each other during the high pressure injection molding process and to compensate for possible alignment differences, while also compressively holding the media in position with the first alignment means are retracted. 
         [0047]    As schematically shown in  FIG. 4A  and best shown for position in  FIG. 7 , the mold tool  32  may preferably includes a plurality of retracting media position holding pins  34  arranged radially outwardly of the stacked media sheets  12  and arranged to contact against the peripheral circumferential edges of the media sheets  12 , thereby temporarily fixing the position of the media sheets  12  within the first mold tool half  36 , at least until the mold tool halves  36  and  38  close against each other to take up and maintain the media sheet positioning. 
         [0048]    One or more pusher members  50  may be provided extending slideably through the lower press portion  44  and operable to move the positioning pin retraction member  52  to retract the media position holding pins  34  when the mold tool halves  36  and  38  close (see  FIG. 4B ) and prior to injection of thermoplastic or resin material. As best shown in  FIG. 7 , the media position holding pins  34 , when extended, may extend into the interior of the mold cavity  46 , the cavity  46  which defines the form of the peripheral support frame  14  of the filtration device or HCA trap  10 . When the media position holding pins  34  retract ( FIG. 4B ), the injection molding process fills the space in the cavity previously occupied by the media position holding pins  34  with plastic material, the now filled space forming part of the peripheral support frame  14 . 
         [0049]    The pusher members  50  may be urged to move in a downward direction  54  (direction according to arrow  54  in  FIG. 4A ), this by the pusher members  50  contacting against the upper press portion  42  or the second mold tool half  38  as the press  30  moves to the closed position (see  FIG. 4B ). 
         [0050]    Movement of the pusher members  50  in the downward direction  54  urges the positioning pin retraction member  52  in a downwards direction  54 , thereby urging the media position holding pins  36  to retract away from the media sheets  12  and to retract substantially from the interior of the mold cavity  46  (see  FIG. 4B ). The downward movement of the pusher members  50  may act against one or more return springs, and may compress the return springs, so that when the press  30  opens ( FIG. 4A ) the media position holding pins  34  are extending into the mold cavity  46  in preparation for receiving and hold an new set of filter media sheet(s)  12  in another product molding cycle. 
         [0051]    According to the invention it is preferred that the first mold tool half  36  and the second mold tool half  38  include complimentary media fixation walls  56 , having complimentary shape and axial alignment and projecting axially from the old tool halves to engage directly and in an aligned fashion against opposing sides of the filter media or HCA media sheet  12 , thereby to compress the media sheets  12  together. One or both of the first  36  and second  38  mold halves may be realized as mold inserts, moveably mounted and located by tool compression springs  40 , the tool compression springs  40  compressively loading and urging the first  36  and second  38  mold halves together, the spring loading maintaining a sufficient compressive force on the media fixation walls  56  holding the media sheet(s)  12  in the desired position in the mold so the retracting media position holding pins  34  can retracted without losing the media positioning in the mold. The media fixation walls  56  may also serve as injection resin boundary walls closing the radial inward side of the mold cavity  46  from the open faces  58 , thereby preventing resin in the mold cavity from reaching and contaminating the open faces  58  of the media sheet(s). 
         [0052]    According to the invention it is preferable that the media position holding pins  36  are not fully retracted away from the media sheets  12  until the media fixation walls  56  contact and begin to compress the media sheets  12  together, the compression thereby holding the media sheets  12  in the desired position in the mold tool so the media position holding pins  36  are no longer required and may be safely retracted. 
         [0053]    The media fixation walls  56  may compress the media sheets  12  with substantial force, a sufficient force of the media fixation walls  56  pressing sealably against the opposing sides of the media to thereby close the radial inner side of the mold cavity preventing the to be injected plastic resin material forming the peripheral support frame  12  from migrating into or onto the open central portion of the encapsulated filtration product or alternately the HCA trap  10 , so that the open faces  58  of the media sheet(s)  12  remain open and unobstructed by the injected plastic resin after the injection molding operation. 
         [0054]      FIG. 7  shows one exemplary embodiment of the first mold tool  36  with the media position holding pins  34  extending into the mold cavity  46  and the media fixation walls  56  separating the mold cavity  46  from the open interior where the open faces  58  of the media sheet  12  will be received and positioned. 
         [0055]    The first mold half  36  and/or the second mold half  38  may including channels  64  machined into the faces of the first mold half  36  and/or the second mold half  38 , the channels conducting injected plastic resin into the mold cavity  46 . 
         [0056]      FIG. 8  shows on exemplary embodiment of a second mold plate (second mold half  38 ) showing channels  64  through which resin  62  or moldable material is delivered to the mold cavity  46 , and tool compression springs  40  compressively loading the inner mold tool portion  66  of the second mold half  38 . The inner mold tool portion  66  is shown removed from and sitting upside down on the mold plate to expose the guide pins  68  of the inner mold tool portion  66 . The guide pins  68  may be received into the interior of the tool compression springs  40  to axially guide the inner mold tool portion  66 . 
         [0057]    In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.