Patent Publication Number: US-10309351-B2

Title: Intake system component of internal combustion engine and method for manufacturing intake system component of internal combustion engine

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an intake system component of an internal combustion engine including a porous material product, which is formed from a porous material, and a resin molded portion, which encompasses an outer edge of the porous material product and which is formed integrally with the porous material product, and to a method for manufacturing the intake system component of the internal combustion engine. 
     Japanese Laid-Open Patent Publication No. 2002-21660 describes an example of an air cleaner for a vehicle internal combustion engine serving as one type of an intake system component. The air cleaner includes a porous material product formed from a porous material such as filter paper, nonwoven fabric, or open-cell sponge. The porous material product forms a wall of a housing of the air cleaner. The publication discloses insertion of the porous material product when molding a resin molded portion of the housing. 
     When forming the wall of the housing with the porous material product, the porous material is thermally pressed prior to the insert-molding. The thermal pressing forms the porous material into a predetermined shape and increases the filling density. This increases the rigidity of the wall. However, the amount of the molten resin with which the outer edge of the porous material product is impregnated is reduced when insert-molding is performed. Thus, the strength bonding the porous material product with the resin molded portion may become low, and the outer edge of the porous material product may be separated from the resin molded portion. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an intake system component of an internal combustion engine that increases the strength bonding a porous material product with a resin molded portion and a method for manufacturing the intake system component of the internal combustion engine. 
     To achieve the above object, an intake system component of an internal combustion engine includes a porous material product and a resin molded portion. The porous material product is formed from a porous material and includes an outer edge and a general portion. The resin molded portion encompasses the outer edge and is formed integrally with the porous material product. The general portion is located outside the resin molded portion. The outer edge has a lower filling density than the general portion. 
     In the structure, the outer edge of the porous material product has a lower filling density than the general portion. When molding the resin molded portion, this easily impregnates the outer edge with molten resin and increases the anchor effect and the strength bonding the porous material product with the resin molded portion. 
     Further, to achieve the above object, a method for manufacturing an intake system component of an internal combustion engine is provided. The intake system component of the internal combustion engine includes a porous material product and a resin molded portion. The porous material product is formed from a porous material and includes an outer edge and a general portion. The resin molded portion encompasses the outer edge and is formed integrally with the porous material product. The method includes forming the porous material product that includes the general portion and a low-density portion by thermally pressing the porous material. The low-density portion has a lower filling density than the general portion. The method further includes molding the resin molded portion by injecting molten resin into a cavity of a mold with at least a distal portion of the low-density portion inserted into the cavity. 
     In this method, the porous material is thermally pressed in the thermal pressing step to form the porous material product including the general portion and the low-density portion. Further, molten resin is injected into the cavity of the mold in the resin molding step to mold the resin molded portion that encompasses at least the distal portion of the low-density portion of the porous material product. The low-density portion has a lower filling density than the general portion. This easily impregnates the outer edge of the porous material product with molten resin and increases the anchor effect and the strength bonding the porous material product with the resin molded portion. 
     Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view showing the structure of an air cleaner serving as an intake system component in one embodiment of an intake system component of an internal combustion engine; 
         FIG. 2  is a partially enlarged cross-sectional view of  FIG. 1 ; 
         FIG. 3A  is a cross-sectional view showing a nonwoven fabric sheet prior to thermal pressing; 
         FIG. 3B  is a cross-sectional view showing the nonwoven fabric sheet (nonwoven fabric material product) subsequent to thermal pressing; and 
         FIG. 4  is a cross-sectional view mainly illustrating a resin molding step in the embodiment and showing a low-density portion of the nonwoven fabric material product and a mold. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment will now be described with reference to  FIGS. 1 to 4 . 
     Referring to  FIG. 1 , an air cleaner is arranged in an intake passage of a vehicle internal combustion engine. The air cleaner includes a first housing  10  having an inlet  18 , a second housing  20  having an outlet  28 , and a filter element  30 . The filter element  30  is located between an upper opening  11  of the first housing  10  and a lower opening  21  of the second housing  20  that opposes the upper opening  11 . 
     The first housing  10  includes a peripheral wall  12 , which surrounds the upper opening  11 , and a bottom wall  13 . A ring-shaped flange  16  projects toward the outer side from the periphery of the upper opening  11 . The inlet  18  is tubular and projects from an outer surface of the peripheral wall  12 . 
     The second housing  20  includes a peripheral wall  22  that surrounds the lower opening  21  and a top wall  23 . A ring-shaped flange  26  projects toward the outer side from the periphery of the lower opening  21 . The outlet  28  is tubular and projects from an outer surface of the peripheral wall  22 . 
     The filter element  30  includes a filtration portion  31 , which is formed by pleating a filter medium sheet such as filter paper or nonwoven fabric, and a ring-shaped seal  32 , which is located on an outer edge of the filtration portion  31 . 
     The seal  32  is held between the flange  16  of the first housing  10  and the flange  26  of the second housing  20  to seal the gap between the first housing  10  and the second housing  20 . 
     The structure of the first housing  10  will now be described in detail. 
     The first housing  10  includes a nonwoven fabric product  14 , which serves as a porous material product, and a resin molded portion  15 . The nonwoven fabric product  14  is formed from a nonwoven fabric sheet serving as a porous material. The resin molded portion  15  is formed from a hard resin material and encompasses an outer edge  46  of the nonwoven fabric product  14 . The nonwoven fabric product  14  is formed integrally with the resin molded portion  15  through insert-molding. 
     The resin molded portion  15  includes the flange  16 , the inlet  18 , a resin wall  17 , and a plurality of ribs  19 . The resin wall  17  forms part of the peripheral wall  12  and is located between the flange  16  and the inlet  18 . The ribs  19  project from an outer surface of the resin wall  17  and the flange  16  and are spaced apart from one another in the circumferential direction. 
     The nonwoven fabric product  14  forms the entire bottom wall  13  and the part of the peripheral wall  12  excluding the resin molded portion  15 . 
     The nonwoven fabric product  14  is formed from known core-sheath composite fibers each including a core (not shown) formed from, for example, polyethylene terephthalate (PET) and a sheath (not shown) formed from denatured PET having a lower melting point than the PET fiber. 
     The nonwoven fabric product  14  is molded by thermally pressing a nonwoven fabric sheet  40  (refer to  FIG. 3A ) having a thickness of, for example, 30 mm to 100 mm. 
     The nonwoven fabric product  14  includes a thick portion  41 , a general portion  43 , and a thickness varying portion  42 . The general portion  43  of the nonwoven fabric sheet  40  has a higher compression degree, or fiber filling density (hereinafter referred to as the filling density), than the thick portion  41 . The thickness varying portion  42  is located between the thick portion  41  and the general portion  43  and is gradually reduced in thickness from the thick portion  41  toward the general portion  43 . The thick portion  41  and the relatively thick part of the thickness varying portion  42  function to deaden the intake noise (hereinafter referred to as noise deadening effect). 
     The thick portion  41  extends from a central part of the bottom wall  13  of the first housing  10  to the peripheral wall  12  that is located at the opposite side (right side as viewed in  FIG. 1 ) of the inlet  18  relative to the central part. It is preferred that the thick portion  41  have a thickness of, for example, 5 mm to 50 mm to avoid enlargement of the nonwoven fabric product  14  and achieve the noise deadening effect. 
     The general portion  43  extends over the entire outer edge of the thickness varying portion  42 . It is preferred that the general portion  43  have a thickness of, for example, 1 mm to 3 mm to facilitate formation of the nonwoven fabric product  14  and ensure the rigidity of the nonwoven fabric product  14 . 
     The outer edge  46  is formed over the entire outer edge of the general portion  43  with a buffer portion  44  and a compressed portion  45  located in between. The buffer portion  44  is located adjacent to the resin molded portion  15  at the outer side of the resin molded portion  15 . The compressed portion  45  is located at the boundary between inside and outside of the resin molded portion  15 . 
     The maximum thickness of the buffer portion  44  and the outer edge  46  is larger than the thickness of the general portion  43 . The buffer portion  44  and the outer edge  46  have a lower filling density than the general portion  43 . The compressed portion  45  is more compressed than the buffer portion  44  and the outer edge  46 , and the compressed portion  45  has a higher filling density than the buffer portion  44  and the outer edge  46 . 
     The structure of the second housing  20  will now be described in detail. 
     As shown in  FIGS. 1 and 2 , the second housing  20  includes a nonwoven fabric product  24  serving as a porous material product and a resin molded portion  25 . The nonwoven fabric product  24  is formed from a nonwoven fabric sheet, which serves as a porous material. The resin molded portion  25  is formed from a hard resin material and encompasses the outer edge  46  of the nonwoven fabric product  24 . The nonwoven fabric product  24  is formed integrally with the resin molded portion  25  through insert-molding. 
     The resin molded portion  25  includes the flange  26 , the outlet  28 , a resin wall  27 , and a plurality of ribs (not shown). The resin wall  27  forms part of the peripheral wall  22  and is located between the flange  26  and the outlet  28 . The ribs project from an outer surface of the resin wall  27  and the flange  26  and are spaced apart from one another in the circumferential direction. 
     The nonwoven fabric product  24  includes the entire top wall  23  and the part of the peripheral wall  22  excluding the resin molded portion  25 . 
     The nonwoven fabric product  24  is formed by thermally pressing the nonwoven fabric sheet  40  in the same manner as the nonwoven fabric product  14  of the first housing  10 . 
     The nonwoven fabric product  24  includes the entire top wall  23  and the general portion  43 . The general portion  43  forms part of the peripheral wall  22  that is continuous with the top wall  23 . The nonwoven fabric product  24  does not include the thick portion  41  and the thickness varying portion  42 . It is preferred that the general portion  43  have a thickness of, for example, 1 mm to 3 mm to facilitate formation of the nonwoven fabric product  24  and ensure the rigidity of the nonwoven fabric product  24 . 
     In the same manner as the nonwoven fabric product  14  of the first housing  10 , the outer edge  46  is formed over the entire outer edge of the general portion  43  with the buffer portion  44  and the compressed portion  45  located in between. 
     The method for manufacturing the first housing  10  and the second housing  20  through insert-molding will now be described. The first housing  10  and the second housing  20  are manufactured by basically the same method. Thus, the method for manufacturing the second housing  20  will be described instead of the method for manufacturing the first housing  10 . 
     Thermal Pressing Step 
     First, referring to  FIGS. 3A and 3B , the nonwoven fabric sheet  40  is thermally pressed to form the nonwoven fabric product  24  including the general portion  43  and a low-density portion  47 . The low-density portion  47  is located at the outer edge of the general portion  43  and has a lower filling density than the general portion  43 . The low-density portion  47  of the present embodiment has an oval cross section. However, the low-density portion  47  may have other cross-sectional shapes such as a rectangular shape. 
     Resin Molding Step 
     Subsequently, as shown in  FIG. 4 , the nonwoven fabric product  24  is placed in a mold  50 . 
     The mold  50  includes a first mold  51  and a second mold  52 . Grooves  511  and  521  defining a cavity  53  are formed in parting surfaces of the first mold  51  and the second mold  52 . 
     Accommodation portions  512  and  522  that accommodate the general portion  43  of the nonwoven fabric product  24  are defined in the parting surfaces. Further, clamping portions  513  and  523  that clamp the low-density portion  47  are formed between the grooves  511  and  521  and the accommodation portions  512  and  522  in the parting surfaces. 
     The mold  50  is closed with a distal portion  471  of the low-density portion  47  of the nonwoven fabric product  24  inserted into the cavity  53  of the mold  50 . The clamping portions  513  and  523  of the mold  50  compress a continuous portion  472  that is continuous with the distal portion  471  of the low-density portion  47 . This forms the outer edge  46  with the distal portion  471  of the low-density portion  47 . 
     In this state, molten resin is injected into the cavity  53 . This forms the resin molded portion  25  as shown in  FIG. 2 . The low-density portion  47  has a lower filling density than the general portion  43 . This easily impregnates the outer edge  46  with molten resin and increases the anchor effect and the strength bonding the nonwoven fabric products  14  and  24  with the resin molded portions  15  and  25 . 
     Further, the clamping portions  513  and  523  of the mold  50  compress the continuous portion  472 . This avoids situations in which the molten resin in the cavity  53  flows toward a basal part of the low-density portion  47 , that is, the buffer portion  44 . 
     When opening the mold  50 , the part that was compressed by the clamping portions  513  and  523  returns to its original shape. As shown in  FIG. 2 , this forms the buffer portion  44 , which has a lower filling density than the general portion  43 , between the resin molded portion  25  of the nonwoven fabric product  24  and the general portion  43 . Further, the compressed portion  45  is formed at the boundary between the inside and outside of the resin molded portion  15 . 
     The intake system component of the internal combustion engine and the method for manufacturing the intake system component of the internal combustion engine of the present embodiment have the advantages described below. 
     (1) The housings  10  and  20  of the air cleaner of the internal combustion engine respectively include the nonwoven fabric products  14  and  24 , which are formed from nonwoven fabric, and the resin molded portions  15  and  25 , which encompass the outer edges  46  of the nonwoven fabric products  14  and  24  and are formed integrally with the nonwoven fabric products  14  and  24 . The outer edges  46  located inside the resin molded portions  15  and  25  have a lower filling density than the general portion  43  located outside the resin molded portions  15  and  25  of the nonwoven fabric products  14  and  24 . 
     In such a structure, the filling density of the outer edges  46  of the nonwoven fabric products  14  and  24 , that is, the fiber filling density is lower than the filling density of the general portion  43 . This reduces the amount of the molten resin with which the outer edges  46  are impregnated when molding the resin molded portion  15  and increases the anchor effect and the strength bonding the nonwoven fabric product  14  with the resin molded portion  15 . 
     (2) The nonwoven fabric molded product  14  includes the buffer portion  44  having a lower filling density than the general portion  43 . The buffer portion  44  is located between the resin molded portion  15  and the general portion  43 . 
     The general portion  43  of the nonwoven fabric product  14  has a high filling density. Thus, when external force such as vibration moves the general portion  43  relative to the resin molded portion  15 , stress tends to concentrate at the resin molded portion  15  that encompasses the outer edge  46 . This may cause separation or breakage of the resin molded portion  15 . 
     In this regard, in the above structure, the buffer portion  44  is formed in the nonwoven fabric product  14 . Thus, the buffer portion  44  absorbs the external force transmitted between the general portion  43  and the resin molded portion  15 . This allows for movement of the general portion  43  relative to the resin molded portion  15  and limits separation and breakage of the resin molded portion  15 . 
     (3) The nonwoven fabric sheet  40  is thermally pressed to form the nonwoven fabric products  14  and  24  that include the general portion  43  and the low-density portion  47 , which has a lower filling density than the general portion  43  (thermal pressing step). Further, molten resin is injected into the cavity  53  with the distal portions  471  of the low-density portions  47  of the nonwoven fabric products  14  and  24  inserted into the cavity  53  of the mold  50  to mold the resin molded portions  15  and  25  (resin molding step). 
     In this method, the nonwoven fabric sheet  40  is thermally pressed in the thermal pressing step to form the nonwoven fabric products  14  and  24  including the general portion  43  and the low-density portion  47 . Further, molten resin is injected into the cavity  53  of the mold  50  in the resin molding step to mold the resin molded portions  15  and  25  that encompass the distal portions  471  of the low-density portions  47  of the nonwoven fabric products  14  and  24 . The low-density portion  47  has a lower filling density than the general portion  43 . This easily impregnates the outer edges  46  of the nonwoven fabric products  14  and  24  with molten resin and increases the anchor effect and the strength bonding the nonwoven fabric products  14  and  24  with the resin molded portions  15  and  25 . 
     (4) In the resin molding step, the continuous portion  472  that is continuous with the distal portion  471  is compressed by the mold  50  with the distal portion  471  of the low-density portion  47  of each of the nonwoven fabric products  14  and  24  inserted into the cavity  53  of the mold  50 . 
     In this method, the continuous portion  472  is compressed by the mold  50  in the resin molding step. When opening the mold  50 , the part that was compressed by the mold  50  returns to its original shape. This forms the buffer portion  44  having a lower filling density than the general portion  43  between the resin molded portions  15  and  25  of the nonwoven fabric products  14  and  24  and the general portion  43 . Thus, the buffer portion  44  is easily formed. 
     Modified Examples 
     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms. 
     The nonwoven fabric product  24  of the second housing  20  may include the thick portion  41 . Additionally, the thick portion  41  may be omitted from the nonwoven fabric product  14  of the first housing  10 . 
     Water-resistant films may be applied to the outer sides of the nonwoven fabric products  14  and  24 . In this case, a nonwoven fabric product can be formed by thermally pressing a nonwoven fabric sheet  40  including the film applied to one of the surfaces of the nonwoven fabric sheet  40 . Even in this case, molten resin is easily impregnated in the resin molding step through the inner surface of each of the nonwoven fabric products  14  and  24 , that is, surface opposite to the film. This increases the anchor effect and the strength bonding the nonwoven fabric product  14  and the resin molded portion  15 . 
     The nonwoven fabric products  14  and  24  do not need to include the buffer portions  44 . In this case, the size of the low-density portion  47  needs to be set so that the entire low-density portion  47  is inserted into the cavity  53 . 
     A porous material product may be formed from, for example, a porous material other than the nonwoven fabric sheet  40  such as open-cell sponge. 
     The present invention may be applied to an intake system component other than an air cleaner, for example, an intake duct. 
     The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.