Abstract:
An air intake duct is disposed in an engine compartment and has wall sections for forming an air passage for introducing air into a combustion chamber of an engine. A support member is disposed on at least a portion of the wall sections, wherein the support member is shrunk when a compressive force of a predetermined value or more is applied from the outside to the wall sections, and at least a portion of the support member is elastically restored when the compressive force decreases.

Description:
[0001]     This application is based on Japanese Patent Application No. 2004-059456, which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an air intake duct for introducing outside air into a combustion chamber of an engine.  
         [0004]     2. Description of the Related Art  
         [0005]     An air intake duct is disposed on a most upstream side of an induction system for allowing the outside and a combustion chamber to communicate with each other (e.g., refer to JP2003-314393 Å). The air intake duct has a wall section for partitioning an air passage. An inlet port section is formed at an upstream end of the wall section. The inlet port section is open in the vicinity of a front edge of an engine compartment. The inlet port section is secured to an upper portion of a radiator upper support of a radiator. Meanwhile, a downstream end of the wall section is connected to a dirty side (an upstream side of an air element) of an air cleaner.  
         [0006]     As described above, the inlet port section is secured to the upper portion of the radiator upper support and is disposed immediately below a hood panel. For this reason, the inlet port section frequently has a flat shape. Accordingly, included among the problems are the rectification of an air current, the securing of rigidity, the occurrence of intake noise due to the membrane vibration of upper and lower walls, and deformation due to intake negative pressure. In this respect, ribs connecting the upper and lower walls are disposed in the inlet port section of JP-A-11-229982.  
         [0007]     However, the inlet port section is disposed immediately below the hood panel. For this reason, it is conceivable that when the hood panel is closed, the hood panel and the inlet port section interfere with each other, causing damage to the ribs. Also, it is conceivable that the ribs may become damaged during the operation of assembling the air intake duct or the like or a light collision of the vehicle. The ribs which have been damaged once are not restored to their original state. Accordingly, the inlet port section becomes crushed. If the inlet port section becomes crushed, the intake sectional area becomes small. For this reason, there is a possibility that it becomes impossible to supply a desired amount of outside air to the combustion chamber.  
       SUMMARY OF THE INVENTION  
       [0008]     The air intake duct of the invention has been completed in view of the above-described problems. Accordingly, an object of the invention is to provide an air intake duct which is capable of supplying a desired amount of outside air to the combustion chamber even after at least apart of the wall section such as the inlet port section has been compressed.  
         [0009]     To overcome the above-described problems, in accordance with the invention there is provided an air intake duct having a wall section in which an air passage for introducing air is formed, characterized by comprising a support member provided a part of the wall section, wherein the support member is elastically deformable to a compressive force of a predetermined value to the wall section, so that the wall section is resiliently restorable when the compressive force is released.  
         [0010]     A support member is disposed on at least a portion of the wall section (e.g., a portion where collision energy is to be consumed). At least a portion of the support member is elastically restorable. For this reason, even if the wall section has been compressed and deformed, at least a portion of the wall section can be restored by making use of the restoring force of the support member. Namely, the passage sectional area of the air passage can be made large as compared with the time when the wall section is compressed. Accordingly, it is possible to supply a desired amount of outside air to the combustion chamber.  
         [0011]     In addition, even if a collision object has ridden over the hood panel during a collision, at least part of the collision energy is consumed as the elastic deformation energy of support member. For this reason, the impact is alleviated.  
         [0012]     Preferably, an inlet port section having a flat cross-sectional shape is disposed at an upstream end of the wall section, and the support member includes a spring member extending in a direction of a short axis of the inlet port section. Namely, in this construction, a spring member is disposed as the support member at the inlet port section disposed at the upstream end of the wall section. According to this construction, the spring member is disposed along the short-axis direction. For this reason, it is possible to easily secure the intake sectional area of the inlet port section even after the inlet port section has been compressed and deformed in the short-axis direction.  
         [0013]     Preferably, an inlet port section having a flat cross-sectional shape is disposed at an upstream end of the wall section, and the support member is a rubber member extending in a direction of a short axis of the inlet port section. Namely, in this construction, a rubber member is disposed as the support member at the inlet port section disposed at the upstream end of the wall section. According to this construction, the rubber member is disposed along the short-axis direction. For this reason, it is possible to easily secure the intake sectional area of the inlet port section even after the inlet port section has been compressed and deformed in the short-axis direction.  
         [0014]     Preferably, the support member includes a rib member extending along a longitudinal direction of the air passage. According to this construction, turbulence is difficult to occur in the air current in the air passage. For this reason, intake resistance becomes small.  
         [0015]     Preferably, a stopper member for suppressing dislocation of the support member is disposed at a portion of the wall section where the support member is disposed. According to this construction, it is possible to suppress the support member from becoming dislocated and entering the downstream side of an induction system due to intake negative pressure. Accordingly, it is possible to effect, among others, the suppression of intake resistance from becoming large.  
         [0016]     Preferably, the stopper member is disposed around a through ole formed in the wall section, and a cover member for covering the support member and the through hole is disposed.  
         [0017]     The inlet port for directly introducing the outside air is in many cases open toward the front side of the vehicle. The reason for this is to introduce cool outside air (outside air having a large air density) so as to enhance the combustion efficiency in the combustion chamber.  
         [0018]     In contrast, the through hole is formed by using as a reference the portion where the stopper member is disposed. For this reason, it is conceivable that relatively warm air (outside air having a small air density) inside the engine compartment enters the air passage through the through hole via a different root from the inlet port. Namely, it is conceivable that the combustion efficiency in the combustion chamber becomes low.  
         [0019]     In view of this aspect, a cover member is provided in this construction. The support member and the through hole are shielded from the air passage by means of the cover member. Consequently, it is possible to suppress relatively warm air from entering the air passage through the through hole. Hence, according to this construction, it is possible to suppress a decline in the combustion efficiency in the combustion chamber. In addition, according to this construction, since the overall surface of the support member is covered with the cover member, the intake resistance attributable to the shape of the support member becomes small.  
         [0020]     Preferably, the cover member is formed of an elastic material. The cover member of this construction is easily compressed and restored. For this reason, at least part of the collision energy can be consumed as the elastically deforming energy of the cover member.  
         [0021]     According to the invention, it is possible to provide an air intake duct which is capable of supplying a desired amount of outside air to the combustion chamber even after at least a part of the wall section has been compressed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a perspective view of an air intake duct in accordance with a first embodiment;  
         [0023]      FIG. 2  is an exploded perspective view of the air intake duct;  
         [0024]      FIGS. 3A  to  3 C are schematic diagrams of that air intake duct prior to a collision (a cross-sectional view taken along line III-III in  FIG. 1 ), during the collision, and after the collision, respectively;  
         [0025]      FIG. 4  is a perspective view of the air intake duct in accordance with a second embodiment;  
         [0026]      FIG. 5  is an exploded perspective view of that air intake duct;  
         [0027]      FIG. 6  is a cross-sectional view taken along line VI-VI in  FIG. 4 ;  
         [0028]      FIG. 7  is a cross-sectional view in a short-axis direction of the air intake duct in accordance with a third embodiment;  
         [0029]      FIG. 8  is a perspective view of a stopper member of that air intake duct;  
         [0030]      FIG. 9  is a cross-sectional view in the short-axis direction of the air intake duct in accordance with a fourth embodiment; and  
         [0031]      FIG. 10  is a perspective view of the stopper member of that air intake duct. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]     Hereafter, a description will be given of the embodiments of the invention.  
       First Embodiment  
       [0033]     First, a description will be given of the construction of an air intake duct in accordance with a first embodiment of the invention.  FIG. 1  shows a perspective view of the air intake duct of this embodiment. It should be noted that a hood panel is shown by a wire frame (shown by chain lines in the drawing) due to the convenience of explanation.  FIG. 2  shows an exploded perspective view of the air intake duct.  FIG. 3A  shows a cross-sectional view taken along line III-III in  FIG. 1 . As shown in these drawings, an air intake duct  1  is comprised of an inlet port section  2 , an air passage section  3 , a rib member  10 , and stopper members  6   a  and  6   b . It should be noted that a wall section of the invention is made up of the inlet port section  2  and the air passage section  3 . Air passages  11  are formed in the interiors of the inlet port section  2  and the air passage section  3 .  
         [0034]     The inlet port section  2  is formed by injection molding polypropylene (PP). The inlet port section  2  has the shape of a flat trapezoidal tube which is wide in the transverse direction of the vehicle and is flattened downward. A pair of securing pieces  22  are formed outside the tube of the inlet port section  2  at its both ends in the transverse direction of the vehicle. A duct-side securing hole  220  is punched in each of the securing pieces  22 .  
         [0035]     Meanwhile, a pair of radiator-side securing holes  900  are punched in a metallic radiator upper support  90  disposed at a front edge of an engine compartment  9 . The dust-side securing holes  220  and the radiator-side securing holes  900  are vertically aligned. A bolt  8  is passed through each dust-side securing hole  220  and is secured in the radiator-side securing hole  900 . The inlet port section  2 , i.e., the air intake duct  1 , is fixed to the radiator upper support  90  by means of the bolts  8 . An inlet port  20  is disposed is disposed inside the tube of the inlet port section  2 . The inlet port  20  is open toward the front side of the vehicle, i.e., a radiator grille  91 .  
         [0036]     The air passage section  3  is formed by injection molding PP. The air passage section  3  continues to a downstream side of the inlet port section  2 . The upstream side of the air passage section  3  has the shape of a flat rectangular tube. The downstream side of the air passage section  3  has a hollow cylindrical shape. A downstream end  30  of the air passage section  3  is connected to a dirty side of an air cleaner (not shown).  
         [0037]     The stopper members  6   a  and  6   b  are formed in the shaped of a rib. The stopper members  6   a  and  6   b  are disposed in the longitudinal direction of the air passage  11 . Of these, the stopper members  6   a  are disposed on an upper surface of a lower wall of the inlet port section  2 . The stopper members  6   b  are disposed on a lower surface of an upper wall of the inlet port section  2  in face-to-face relation to the stopper members  6   a . These stopper members  6   a  and  6   b , the inlet port section  2 , and the air passage section  3  are fabricated by first fabricating by injection molding a lower split body consisting of the stopper members  6   a , a lower half of the inlet port section  2 , and a lower half of the air passage section  3 , by fabricating an upper split body consisting of the stopper members  6   b , an upper half of the inlet port section  2 , and an upper half of the air passage section  3 , and then by joining the lower split body and the upper split body. According thereto, the air intake duct  1  is formed.  
         [0038]     The rib members  10  are made of a rubber and connect the upper and lower walls of the inlet port section  2 . The rib members  10  are disposed along the longitudinal direction of the air passage  11 . In addition, the rib members  10  are arranged in three rows in such a manner as to be juxtaposed in the transverse direction of the vehicle. A lower edge of each rib member  10  is clamped and fixed from both sides in the transverse direction of the vehicle by the pair of stopper members  6   a . Meanwhile, the pair of stopper members  6   b  are press fit to an upper edge of the rib member  10  just like wedges.  
         [0039]     Next, a description will be given of the movement of the air intake duct of this embodiment during a collision.  FIGS. 3A  to  3 C are schematic diagrams of the air intake duct of this embodiment prior to a collision, during the collision, and after the collision, respectively.  
         [0040]     As shown in  FIG. 3A , a collision object W collides against a hood panel  92  from above. As shown in  FIG. 3B , the collided portion of the hood panel  92  is crushed and deformed downward due to the collision by the collision object W. The upper wall of the inlet port section  2  is also crushed and deformed downward. In addition, the rib members  10  are compressed and deformed downward and expand in the transverse direction of the vehicle. Through the above-described series of deformations the vertical width of the inlet port section  2  becomes small. That is, the inlet port section  2  collapses. Also, through the above-described series of deformations the collision energy is consumed. When the colliding force becomes small and the colliding force becomes smaller than the restoring force (elastically deforming force), the rib members  10  are restored, as shown in  FIG. 3C . When the rib members  10  are restored, the upper wall of the inlet port section  2  is also restored. For this reason, it is possible to secure substantially the same intake sectional area as before the collision. In addition, the collided portion of the hood panel  92  is also pushed upward together with the upper wall of the inlet port section  2 . For this reason, the collided portion of the hood panel  92  is also restored partially.  
         [0041]     Next, a description will be given of the operation and effects of the air intake duct in accordance with this embodiment. According to the air intake duct  1  of this embodiment, the rib members  10  are elastically restorable. For this reason, even if the inlet port section  2  has been compressed and deformed, the inlet port section  2  can be restored. Accordingly, it is possible to supply a desired amount of outside air to a combustion chamber.  
         [0042]     In addition, as shown in  FIGS. 3A  to  3 C referred to above, even if the collision object W has ridden over the hood panel  92  during a collision, part of the collision energy is consumed as the elastic deformation energy of the rib members  10 . For this reason, the impact to which the collision object W is subjected is alleviated.  
         [0043]     In addition, the stopper members  6   a  and  6   b  are disposed in the air intake duct  1  of this embodiment. For this reason, it is possible to suppress the rib members  10  from becoming dislocated and entering the downstream side of the induction system due to intake negative pressure. Accordingly, it is possible to effect, among others, the suppression of intake resistance from becoming large.  
         [0044]     In addition, according to the air intake duct  1  of this embodiment, rib members  10  are juxtaposed in parallel in three rows. For this reason, during a collision, collision energy is easily consumed as the elastic deformation energy. In addition, front and rear edges of the rib members  10  are formed into a chamfered, rounded shape. For this reason, turbulence is difficult to occur in the outside air introduced through the inlet port  20 . In addition, the rib members  10  extend along the longitudinal direction of the air passage  11 . Hence, the rectification effect is high.  
       Second Embodiment  
       [0045]     First, a description will be given of the construction of the air intake duct in accordance with a second embodiment of the invention.  FIG. 4  shows a perspective view of the air intake duct of this embodiment. It should be noted that portions corresponding to those of  FIG. 1  are denoted by the same reference numerals.  FIG. 5  shows an exploded perspective view of the air intake duct. It should be noted that portions corresponding to those of  FIG. 2  are denoted by the same reference numerals.  FIG. 6  shows a cross-sectional view taken along line VI-VI in  FIG. 4 . It should be noted that portions corresponding to those of  FIGS. 3A  to  3 C are denoted by the same reference numerals.  
         [0046]     As shown in these drawings, the stopper member  6   a  is formed in the shape of an annular rib. A circumferentially continuous engaging pawl  62  is formed on an upper end of the stopper member  6   a . The stopper member  6   a  is provided in such a manner as to project from the lower wall of the inlet port section  2 . A through hole  21  is formed on the inner peripheral side of the stopper member  6   a . The stopper member  6   a  has the shape of a short-axis cylinder. The stopper member  6   b  is provided in such a manner as to project from the upper wall of the inlet port section  2  toward the stopper member  6   a . The outer shape of a rubber member  7  has the shape of a hollow truncated cone whose diameter decreases gradually from the lower side toward the upper side. In addition, the rubber member  7  has the shape of a cup which is open toward the lower side. An engaged groove  71  is circumferentially provided at a lower edge of an inner peripheral surface of the rubber member  7 . Meanwhile, a recessed portion  70   b  is provided in a recessed manner in an upper bottom wall of the rubber member  7 . The engaging pawl  62  of the stopper member  6   a  is retained in the engaged groove  71 . The stopper member  6   b  is press fit into the recessed portion  70   b . As the stopper member  6   a  is retained and the stopper member  6   b  is press fit, the rubber member  7  is secured in the inlet port section  2 .  
         [0047]     The air intake duct  1  of this embodiment exhibits the operation and effects similar to those of the air intake duct of the first embodiment. In addition, the through hole  21  is formed in the air intake duct  1  of this embodiment. However, the rubber member  7  itself has airtightness. For this reason, the through hole  21  can be shielded from the air passage  11  by the rubber member  7 .  
       Third Embodiment  
       [0048]     The air intake duct in accordance with a third embodiment of the invention differs from the second embodiment in that a spring member is disposed instead of the rubber member. Further, the shapes of the stopper members also differ. Furthermore, a cover member is disposed on an outer peripheral side of the spring member. Accordingly, a description will be given only of the differences.  
         [0049]      FIG. 7  shows a cross-sectional view in a short-axis direction of the air intake duct in accordance with this embodiment. It should be noted that portions corresponding to those of  FIG. 6  are denoted by the same reference numerals.  FIG. 8  shows a perspective view of the stopper member of the air intake duct. It should be noted that portions corresponding to those of  FIG. 5  are denoted by the same reference numerals. A spring member  4  is made of steel and has the shape of a hollow truncated cone whose diameter decreases gradually from the lower side toward the upper side, as shown in  FIG. 7 . A rubber-made cover member  5  is disposed on the outer peripheral side of the spring member  4 . The cover member  5  has the shape of a hollow truncated cone whose diameter decreases gradually from the lower side toward the upper side.  
         [0050]     As shown in  FIG. 8 , the stopper member  6   a  has the shape of an annular rib. The stopper member  6   a  is formed such that its diameter increases gradually from the lower side toward the upper side. Axial slits  60  and radial slits  61  are formed in the stopper member  6   a . The axial slit  60  and the radial slit  61  continue in an L-shape. The axial slits  60  and the radial slits  61  are respectively disposed in such a manner as to be spaced apart from each other at intervals of 60° in the circumferential direction, and a total of six slits are provided, respectively. The through hole  21  is formed on the inner peripheral side of the stopper member  6   a . A lower-end loop of the spring member  4  is fitted over the stopper member  6   a . Meanwhile, the stopper member  6   b  has the shape of an annular rib. An upper-end loop of the spring member  4  is fitted over the stopper member  6   b.    
         [0051]     The air intake duct  1  of this embodiment exhibits the operation and effects similar to those of the air intake duct of the first embodiment. In addition, according to the air intake duct  1  of this embodiment, when the spring member  4  is fitted over the stopper member  6   a , the stopper member  6   a  is deformed in the diameter-reducing direction and in the downward direction by the portions of the axial slits  60  and the radial slits  61 . For this reason, the assembly of the spring member  4  is facilitated.  
         [0052]     In addition, as described above, the stopper member  6   a  is formed such that its diameter increases gradually from the lower side toward the upper side. Meanwhile, the spring member  4  is formed such that its diameter decreases gradually from the lower side toward the upper side. The inner peripheral diameter of the lower end loop of the spring member  4  is set to be smaller than the outer peripheral diameter of the upper edge of the stopper member  6   a . For this reason, the spring member  4  is difficult to come off the stopper member  6   a.    
         [0053]     In addition, when the spring member  4  is shrunk, the loops making up the spring member  4  are difficult to interfere each other. Namely, as described before, the spring  4  is formed such that its diameter decreases gradually from the lower side toward the upper side. For this reason, the diameter of the upper loop is smaller than that of the lower loop. Accordingly, when the spring member  4  is shrunk, the upper loop is accommodated on the inner peripheral side of the lower loop between vertically adjacent ones of the loops. Since this accommodating operation is effected over the entire length of the spring member  4 , the spring member  4  is accommodated in the through hole  21  on the inner peripheral side of the stopper member  6   a . Hence, according to the air intake duct  1  of this embodiment, the allowance of the elastic deformation of the spring member  4  becomes large. For this reason, during a collision, the collision energy is easily consumed as the elastic deformation energy.  
         [0054]     In addition, the cover member  5  is disposed in the air intake duct  1  of this embodiment. The cover member  5  covers the spring member  4  and the through hole  21 . Namely, the cover member  5  isolates the through hole  21  from the air passage  11 . For this reason, it is possible to suppress relatively warm air in the engine compartment  9  from entering the air passage  11  through the through hole  21 . Accordingly, it is possible to suppress a decline in the combustion efficiency in the combustion chamber. In addition, since the overall surface of the spring member  4  is covered with the cover member  5 , the intake resistance attributable to the shape of the spring member  4  becomes small. Furthermore, the cover member  5  is made of rubber which is an elastic material. For this reason, the collision energy can be consumed as the elastic deformation energy by not only the deformation of the spring member  4  but also the deformation of the cover member  5 . Namely, the function of the spring member  4  can be assisted by the cover member  5 .  
       Fourth Embodiment  
       [0055]     Differences between the air intake duct in accordance with a fourth embodiment of the invention and the third embodiment lie in the shape of the spring member and the shape of the stopper member on the lower wall side of the inlet port section. Accordingly, a description will be given only of the differences.  
         [0056]      FIG. 9  shows a cross-sectional view in the short-axis direction of the air intake duct in accordance with this embodiment. It should be noted that portions corresponding to those of  FIG. 7  are denoted by the same reference numerals.  FIG. 10  shows a perspective view of the stopper member of the air intake duct of this embodiment. It should be noted that portions corresponding to those of  FIG. 8  are denoted by the same reference numerals. The axial slits  60  are formed in the stopper member  6   a , as shown in  FIG. 10 . The axial slit  60  are disposed in such a manner as to be spaced apart from each other at intervals of 60° in the circumferential direction, and a total of six slits are provided. In addition, the spring member  4  and the cover member  5  have hollow cylindrical shapes. The air intake duct of this embodiment exhibits the operation and effects similar to those of the air intake duct of the first embodiment. In addition, according to the air intake duct of this embodiment, when the spring member  4  is fitted over the stopper member  6   a , the stopper member  6   a  undergoes a reduction in diameter and deformation by the portion of the axial slits  60 . For this reason, the assembly of the spring member  4  is facilitated.  
         [0057]     A description has been given above of the embodiments of the air intake duct in accordance with the invention. However, the invention is not limited to the above-described embodiments and may be implemented in various forms of modification or improvement which may be carried out by those skilled in the art.  
         [0058]     For instance, in the above-described embodiments the inlet port section  2  and the air passage section  3  are formed by the injection molding of PP, by may be formed of PE (polyethylene), PA (polyamide), or the like. In addition, the inlet port section  2  and the air passage section  3  may be fabricated separately and may subsequently be joined together. In addition, the inlet port section  2  and the air passage section  3  may be fabricated integrally by blow molding.  
         [0059]     In addition, in the above-described embodiments, the rib members  10 , the rubber member  7 , and the spring member  4  are assembled to the inlet port section  2  after the molding of the inlet port section  2  and the air passage section  3 . However, the rib members  10 , the rubber member  7 , and the spring member  4  may be assembled to the inlet port section  2  by insert molding simultaneously with the molding of the inlet port section  2  and the air passage section  3 .  
         [0060]     In addition, in the case where the spring member  4  in the form of a coil spring is used as a support member, the restoring force (elastically deforming force) may be adjusted by the number of coils, coil shape, pitch, wire diameter, material, and the like. Also, in the case where the rubber member  7  and the rib members  10  are used as the support members, the restoring force (elastically deforming force) may be adjusted by the material, thickness, and the like.  
         [0061]     In addition, although the spring member  4  in the form of the coil spring is used in the third and fourth embodiments, the shape of the spring member is not particularly limited and may be in the form of a leaf spring, a coned disc spring, or the like.  
         [0062]     In addition, as the support members, the rib members  10 , the rubber member  7 , and the spring member  4  may be used by being combined in parallel or in series. Further, the support members may not connect the upper and lower walls of the inlet port section  2 . Namely, a gap may be present between the support member and the upper wall or between the support member and the lower wall. Furthermore, not all of the support members may be restored after the collision. It suffices if a sectional area of the passage sufficient to supply a predetermined amount of outside air to the combustion chamber can be secured in the air passage  11 . In addition, an air cylinder, an oil cylinder, or the like may be used as the support member. The reason for this is that the support member is restorable by the elastically deforming force of a fluid in the cylinder.  
         [0063]     In addition, although the support member is disposed in the inlet port section  2  in the above-described embodiments, the support member may be disposed in the air passage section  3 . Furthermore, the support members may be disposed both in the inlet port section  2  and in the air passage section  3 . Namely, the support member may be disposed at a desired portion where the collision energy is to be consumed.