Patent Publication Number: US-2018045147-A1

Title: Internal combustion engine

Description:
TECHNICAL FIELD 
     The present invention relates to an internal combustion engine for a vehicle, and in particular to a protection structure for a fuel delivery pipe. 
     BACKGROUND ART 
     In an internal combustion engine mounted laterally on a vehicle with the intake side of the engine facing forward, it is known to extend the branch pipes of an intake manifold from the front side of the cylinder head in a forward and upward direction along an arcuate path, and position a fuel delivery pipe for distributing fuel to a plurality of fuel injectors of the engine between the branch pipes and the front side of the cylinder head. See WO2012/014378A1, for instance. 
     In such an engine, a protective structure is typically provided in front of a throttle valve and a trunk pipe to prevent an impact caused by a frontal crash of the vehicle may not be transmitted to the throttle valve and the trunk pipe. However, the protective structure adds to the weight and cost of the vehicle. 
     SUMMARY OF THE INVENTION 
     In view of such a problem of the prior art, a primary object of the present invention is to provide an internal combustion engine for a vehicle in which a vulnerable part such as a fuel delivery pipe and fuel injectors is favorably protected from a load of a frontal crash without adding any heavy or costly protective structure. 
     To achieve such an object, the present invention provides an internal combustion engine for a vehicle, comprising: an engine main body ( 11 ) having an intake side ( 18 A) disposed on a front side of the vehicle; an intake manifold ( 31 ) including a plurality of branch pipes ( 43 ) extending from first ends attached to the intake side of the engine main body, an intake chamber member ( 42 ) connected to second ends of the branch pipes and elongated in a lateral direction of the vehicle and a trunk pipe ( 41 ) extending from the intake chamber member in the lateral direction; a throttle valve ( 30 ) connected to one end of the trunk pipe with respect to the lateral direction; and a guide portion ( 65 ) attached to or formed on a part of the intake side of the engine main body opposing the throttle valve and having a slant that recedes rearward toward an outboard side of the vehicle. 
     According to this arrangement, when the throttle valve is pushed rearward by an impact of a frontal crash, the throttle valve is guided in the outboard direction by the guide portion so that the throttle valve is prevented from coming into contact with important and vulnerable component parts such as a fuel delivery pipe and fuel injections which are provided on the intake side of the engine main body. The guide portion may be formed by a part of an existing component part so that no extra member is required for the protection of the vulnerable component parts. Therefore, the weight and the cost of the vehicle body can be reduced. 
     The internal combustion engine may further comprise a first support member ( 50 ) connecting one end of the intake chamber member with respect to the lateral direction with the engine main body, the guide portion being formed on the first support member. 
     Because the guide portion is formed on the first support member connected between the intake manifold and the engine main body, no extra member is required for forming the guide portion, and the guide portion can be positioned adjacent to the a fuel delivery pipe so that the contact between the vulnerable part such as a fuel delivery pipe and the throttle valve can be avoided in an effective manner. 
     The internal combustion engine may further comprise a connecting member ( 80 ) having a rear end connected to the first support member and a front end connected to a part of the trunk pipe adjoining the throttle valve. 
     The connecting member is effective in preventing the rear ward travel of the end of the trunk pipe adjoining the throttle valve and the throttle valve itself so that the contact between the vulnerable part such as a fuel delivery pipe and the throttle valve can be avoided in an even more effective manner. 
     The rear end of the connecting member ( 80 ) may be connected to the first support member so as to be pivotable around a vertically extending rotational center line. 
     Thus, when a load caused by a frontal crash of the vehicle is applied to the throttle valve, the throttle valve is guided in the outboard direction jointly by the guide portion and the pivotable connecting member. 
     The rear end of the connecting member ( 80 ) may be fastened to the first support member via a threaded bolt ( 81 ) extending vertically. 
     Thereby, the connecting member and the first support member may be pivotally coupled to each other in a highly simple manner. 
     In a preferred embodiment of the present invention, an internal EGR passage ( 34 ) opens out at the intake side of the engine main body, and the trunk pipe is formed with an EGR introduction hole ( 54 ), and wherein the first support member abuts the engine main body, the intake chamber member and the trunk pipe, and internally defines a connection passage ( 57 ) communicating the internal EGR passage with the EGR introduction hole. 
     Thereby, the first support member also serves for defining the passage the internal EGR passage with the EGR introduction hole so that the number of component parts can be reduced. 
     In a preferred embodiment of the present invention, the trunk pipe extends in an oblique direction so that a throttle valve side part thereof is positioned more forward than an intake chamber member side part thereof, and a front side of the throttle valve side part of the trunk pipe is positioned more forward than a front side of the branch pipes. 
     According to this arrangement, the load of a frontal crash is preferentially supported by the trunk pipe over the branch pipes so that the load is significantly absorbed by the trunk pipe so that the deformation of the branch pipes and the intake chamber member is controlled. As a result, the vulnerable part such as a fuel delivery pipe positioned on the intake side of the engine main body and behind the branch pipes can be favorably protected from the load of a frontal crash. 
     The internal combustion engine may further comprise a fuel delivery pipe extending laterally in a space defined between the intake side of the engine main body and the branch pipes. 
     Thus, a vulnerable part such as a fuel delivery pipe and fuel injectors is favorably protected from a load of a frontal crash without adding any heavy or costly protective structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
         FIG. 1  is a plan view of a front part of a vehicle provided with an internal combustion engine embodying the present invention; 
         FIG. 2  is a perspective view of the engine as seen from a forward and rightward direction; 
         FIG. 3  is a plan view of a front part of the engine; 
         FIG. 4  is a front view of an upper front part of the engine; 
         FIG. 5  is a rear view of an intake manifold; 
         FIG. 6  is a sectional view taken along line VI-VI of  FIG. 4 ; 
         FIG. 7  is a perspective view of a first support member as seen from a forward and leftward direction; 
         FIG. 8  is a plan view of the first support member; 
         FIG. 9  is a perspective view of a second support member as seen from a forward and rightward direction; 
         FIG. 10 a    is a plan view of the second support member before a frontal crash; 
         FIG. 10 b    is a view similar to  FIG. 10 a    after the frontal crash; 
         FIG. 11 a    is a plan view of a throttle valve and a surrounding region when a trunk pipe has ruptured and a throttle valve has traveled rearward in an early phase of a frontal crash; and 
         FIG. 11 b    is a view similar to  FIG. 11 a    when the throttle valve has traveled further rearward and has come into contact with a guide portion in a later phase of the frontal crash. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     A preferred embodiment of the present invention is described in the following with reference to the appended drawings. The directions mentioned in the following disclosure are defined with respect to a vehicle on which an internal combustion engine embodying the present invention is mounted. 
     As shown in  FIG. 1 , an internal combustion engine  1  for an automobile is disposed in an engine room  3  formed in a front portion of a vehicle  2 . On the front side of the engine room  3  of the vehicle  2 , a substantially rectangular frame-like bulkhead  4  having an opening facing in the fore and aft direction is provided. A radiator  5  for cooling the cooling water circulating through the internal combustion engine  1  is supported at a rear portion of the bulkhead  4 . A front part of the engine room  3  is defined by a front bumper face  6  arranged on the front side of the bulkhead  4  and the left and right side parts of the engine room  3  are defined by respective front fenders  7 . 
     The internal combustion engine  1  includes a main body  11 , an intake device  12  and an exhaust device  13  coupled to the engine main body  11 . As shown in  FIG. 2 , the engine main body  11  includes a cylinder block  16  having a plurality of cylinders  15  formed therein, a cylinder head  18  coupled to an upper end of the cylinder block  16  and formed with combustion chamber recesses  17  corresponding to the cylinders  15 , a head cover  19  coupled to the upper end of the cylinder head  18 , an oil pan  21  coupled to a lower end of the cylinder block  16 , and a chain case  22  connected to a cylinder row end of the cylinder block  16 , the cylinder head  18  and the head cover  19 . The chain case  22  defines a space accommodating a timing chain coupled between a camshaft and a crankshaft, in cooperation with the cylinder block  16 , the cylinder head  18  and the head cover  19 . 
     As shown in  FIG. 1 , the engine main body  11  is positioned behind the radiator  5 , and is arranged in the engine room  3  laterally so that the cylinder row extends in the widthwise direction of the vehicle. An intake port  25  and an exhaust port  26  extending from each combustion chamber recess  17  are formed in the cylinder head  18 . The intake port  25  opens to the intake side  18 A (the front side) of the cylinder head  18  extending along the cylinder row direction, and the exhaust port  26  opens to the exhaust side  18 B (the rear side) of the cylinder head  18  extending along the cylinder row direction. 
     The intake device  12  internally defines a series of passages for supplying fresh air to the cylinders  15  of the engine  1 , and includes an air inlet  28 , an air cleaner  29 , a throttle valve  30 , and an intake manifold  31 , in this order from the upstream end. The air inlet  28  is supported on the upper portion of the bulkhead  4 , and the air cleaner  29  is disposed on the left rear side of the radiator  5 . The throttle valve  30  and the intake manifold  31  are disposed behind the radiator  5 . The intake device  12  is attached to the intake side  18 A of the cylinder head  18  via the intake manifold  31 , and communicates with the intake ports  25 . 
     The exhaust device  13  includes an exhaust manifold  33  attached to the exhaust side  18 B of the cylinder head  18 , an exhaust gas purification device, a muffler, and an exhaust outlet, in this order from the upstream end. A left end part of the cylinder head  18  internally defines an internal EGR passage  34  passed through from the exhaust side  18 B to the intake side  18 A. The exhaust manifold  33  is connected to the rear end of the internal EGR passage  34 . 
     On the intake side  18 A of the cylinder head  18 , fuel injectors  36  are passed into the respective combustion chamber recesses  17  (see  FIG. 6 ). The inner end of each fuel injector  36  is provided with an injection hole, and protrudes into the corresponding combustion chamber recess  17  while the outer end of the fuel injector  36  protrudes forward on the intake side  18 A. As shown in  FIGS. 1 to 4 , a fuel delivery pipe  37  extending in the width-wise direction of the vehicle is disposed in front of the intake side  18 A, and the outer ends of the respective fuel injectors  36  are connected to the fuel delivery pipe  37 . A fuel supply pipe  38  having a smaller cross-sectional area than the fuel delivery pipe  37  is connected to the left end of the fuel delivery pipe  37  (see  FIG. 3 ). The fuel supply pipe  38  is connected to a fuel tank via a fuel pump (not shown in the drawings). 
     As shown in  FIGS. 2 to 5 , the intake manifold  31  includes a trunk pipe  41 , an intake chamber member  42 , and a plurality of branch pipes  43 . One ends of the branch pipes  43  are connected to a common branch pipe flange  44  extending in the cylinder row direction and fastened to the intake side  18 A of the cylinder head  18 . Each branch pipe  43  extends from the one end connected to the intake side  18 A of the cylinder head  18  along a curved path having a convex side facing in a forward and upward direction. The branch pipes  43  are arranged one next to the other in the lateral direction of the vehicle. Each branch pipe  43  includes a linear section extending from the branch pipe flange  44  by a prescribed length. 
     The intake chamber member  42  is provided with a box shape elongated in the lateral direction of the vehicle. The intake chamber member  42  internally defines a chamber having a larger cross sectional area than the trunk pipe  41 . The upper end of each branch pipe  43  is connected to the front side of the intake chamber member  42 . The portions at which the branch pipes  43  are connected to the intake chamber member  42  are arranged in a row extending in the lateral direction of the vehicle. 
     The trunk pipe  41  extends from the intake chamber member  42  in the lateral direction of the vehicle. More specifically, one end of the trunk pipe  41  is connected to a central portion of the lower wall of the intake chamber member  42  with respect to the lateral direction of the vehicle, extends downward from the intake chamber member  42 , and bends rightward. The downstream portion  41 A of the trunk pipe  41  is disposed under the intake chamber member  42  and behind two of the branch pipes  43 , and the upstream portion  41 B of the trunk pipe  41  extends beyond the leftmost branch pipe  43 . The front portion of the downstream portion  41 A of the trunk pipe  41  is integrally formed with some of the branch pipes  43  arranged on the left side. 
     A portion of the upstream portion  41 B of the trunk pipe  41  extending leftward beyond the branch pipes  43  protrudes progressively forward toward the left end (upstream end) thereof. A trunk pipe flange  46  extends radially from the upstream end (left end) of the trunk pipe  41 , and a throttle valve  30  is attached to the trunk pipe flange  46  with threaded bolts. The throttle valve  30  is provided with a per se known structure, and includes, for example, a casing  30 A that defines an intake passage, a butterfly valve supported by the casing  30 A, and an electric motor that drives the butterfly valve. The casing  30 A of the throttle valve  30  has higher stiffness than the trunk pipe  41 . The upstream side of the casing  30 A of the throttle valve  30  is connected to the air cleaner  29  via a pipe that internally defines an intake passage. 
     As shown in  FIGS. 3 to 5 , the left end portion (which is one end portion in the lateral direction of the vehicle) of the intake chamber member  42  and the trunk pipe  41  are attached to the intake side  18 A of the cylinder head  18  via a first support member  50 . Further, the right end portion (which is the other end portion in the lateral direction of the vehicle) of the intake chamber member  42  is attached to the intake side  18 A of the cylinder head  18  via a second support member  51 . 
     As shown in  FIG. 5 , the intake chamber member  42  is provided with a left chamber extension  42 A protruding to a leftward and downward direction and connected to the rear side of the trunk pipe  41  at the left end portion of the rear side thereof The left chamber extension  42 A and a rear part of the trunk pipe  41  jointly define a left side fastening seat surface  53  facing rearward. The left side fastening seat surface  53  forms a planar fastening surface facing rearward. A hole or a recess may be formed in an appropriate part of the left chamber extension  42 A for reducing the weight. In a part of the left side fastening seat surface  53 , an EGR introduction hole  54  is bored into the fastening surface in the fore and aft direction so as to reach the interior of the trunk pipe  41 . The left side fastening seat surface  53  extends downward and to the left beyond the EGR introduction hole  54  and the trunk pipe  41 , and a bolt hole  53 A is passed through the protruding part of the left side fastening seat surface  53 . A bolt hole  53 B extending in the fore and aft direction is formed in a portion of the left side fastening seat surface  53  corresponding to the left chamber extension  42 A and located above the EGR introduction hole  54  and the trunk pipe  41 . 
     As shown in  FIGS. 7 and 8 , the first support member  50  is provided with a rear fastening portion  55  and a front fastening portion  56  provided on the front side of the rear fastening portion  55 . The rear end of the rear fastening portion  55  has a rear fastening surface  55 A facing rearward, and a front end of the front fastening portion  56  is provided with a planar front fastening surface  56 A facing forward. The front fastening portion  56  is offset upward and rightward with respect to the rear fastening portion  55 . Similarly, the front fastening surface  56 A is offset upward and rightward with respect to the rear fastening surface  55 A. The front fastening surface  56 A and the rear fastening surface  55 A are substantially parallel to each other. Inside the rear fastening portion  55  and the front fastening portion  56 , an EGR connection passage  57  is passed through in the fore and aft direction. The rear end of the EGR connection passage  57  opens rearward to the rear fastening surface  55 A, and the front end thereof opens forward into the inside of an extension pipe  61  projection from the front fastening surface  56 A. An EGR connection passage  57  extends from the rear end opening out to the rear fastening surface  55 A to the front end along a path curving upward and downward. 
     The rear fastening portion  55  extends in the lateral direction of the vehicle, and the EGR connection passage  57  opens at a central part of the rear fastening surface  55 A with respect to the lateral direction of the vehicle. A pair of bolt holes  58 A and  58 B are passed through the lateral end portions of the rear fastening portion  55  in the fore and aft direction. The left bolt hole  58 A may be offset vertically relative to the right bolt hole  58 B. As shown in  FIGS. 3 and 4 , the rear fastening surface  55 A of the first support member  50  abuts the fastening surface  18 C formed around the internal EGR passage  34  on the intake side  18 A of the cylinder head  18  via a gasket, and the rear end of the EGR connection passage  57  is connected to the internal EGR passage  34 . The first support member  50  is fastened to the cylinder head  18  via threaded bolts  59  which are passed through the respective bolt holes  58 A and  58 B, and threaded into female threaded holes formed in the fastening surface  18 C of the cylinder head  18 . 
     As shown in  FIGS. 7 and 8 , the front fastening portion  56  extends vertically, and an extension pipe  61  is provided in a central part thereof with respect to the vertical direction of the front fastening surface  56 A. A pair of female threaded holes  62 A and  62 B are formed at two vertical end portions of the front fastening surface  56 A, respectively. The upper female threaded hole  62 A is disposed to the right of the extension pipe  61 , and the lower female threaded hole  62 B is disposed to the left of the extension pipe  61 . The lower female threaded hole  62 B is formed as a blind hole, and is positioned so as to correspond to the rear end of the EGR connection passage  57  as viewed from the front. In other words, the lower female threaded hole  62 B is positioned so as to be intermediate between the left and right bolt holes  58 A and  58 B of the rear fastening portion  55  as viewed from the front. As shown in  FIGS. 3 and 4 , in the first support member  50 , the front fastening surface  56 A is brought into contact with the left side fastening seat surface  53  of the intake manifold  31  via a gasket so that the extension pipe  61  is inserted into the EGR introduction hole  54 . The first support member  50  is fastened to the intake manifold  31  by threaded bolts  63  and  63  threaded into the corresponding female threaded holes  62 A and  62 B of the first support member  50  after passing through the bolt holes  53 A and  53 B of the left side fastening seat surface  53 . The free end of the extension pipe  61  is curved in the trunk pipe  41  so as to face in the downstream direction or rightward. 
     As shown in  FIGS. 3 and 4 , the upper surface of the rear fastening portion  55  and the rear surface of the portion protruding upward from the rear fastening portion  55  of the front fastening portion  56  are disposed so as to be orthogonal to each other, and are connected to each other by triangular reinforcement ribs  64 . The number of the reinforcement ribs  64  may be freely selected, and in the present embodiment, two of the reinforcement ribs  64  are arranged in a laterally spaced apart relationship. 
     A guide portion  65  projects leftward from the left surface of the front fastening portion  56 . The guide portion  65  is formed as a plate portion having a major plane facing vertically, and an edge portion thereof protruding to the left is inclined so as to protrude leftward (laterally outward direction of the vehicle) toward the rear end thereof. The rear end of the guide portion  65  is connected to the front surface of the rear fastening portion  55 . The guide portion  65  defines the left side edge of the first support member  50  and is inclined so as to slant leftward toward the rear. The guide portion  65  also functions as a reinforcing structure for the first support member  50 . The left bolt hole  58 A of the rear fastening portion  55  is disposed under the guide portion  65 . 
     The intake chamber member  42  is provided with a right chamber extension  42 B protruding to the right and downward at the rear right end portion thereof. A reinforcing rib may be formed on the surface of the right chamber extension  42 B. A bolt hole  66  extending in the fore and aft direction is passed through the right chamber extension  42 B. 
     As shown in  FIGS. 2 to 4 , a part of the engine main body  11  which is located behind the right chamber extension  42 B is provided with a support table  67  protruding forward along the intake side  18 A of the cylinder head  18 . In the illustrated embodiment, the support table  67  is integrally formed with the chain case  22  and extends forward from the front edge portion of the chain case  22  beyond the intake side  18 A. The support table  67  is preferably in contact with the intake side  18 A. Alternatively, the support table  67  may protrude from the cylinder head  18  or the cylinder block  16 . The support table  67  has a planar upper surface facing upward. 
     As shown in  FIG. 9 , the second support member  51  is a plate like member having a prescribed thickness. The second support member  51  is elongated laterally and is attached to the upper surface of the support table  67  at a right end portion  51 A thereof. The right end portion  51 A of the second support member  51  is disposed on the upper surface of the support table  67  such that the major plane thereof faces vertically. A pair of bolt holes  68 A and  68 B extending vertically (thickness-wise direction) are passed through the right end portion MA of the second support member  51 . The second support member  51  is fastened to the upper surface of the support table  67  by inserting a pair of threaded bolts  69 A and  69 B into the respective bolt holes  68 A and  68 B from above, and threading the two threaded bolts  69 A and  69 B into corresponding female threaded holes  70 A and  70 B formed on the upper side  9  of the support table  67 . 
     A projecting piece  71  projects rearward from the rear edge of the second support member  51 . As shown in  FIG. 3 , a stopper  72  is positioned above the upper surface of the support table  67  and opposes the projecting piece  71  from the right direction of the projecting piece  71  via a gap. In the present embodiment, the stopper  72  is formed by the side end of the peripheral flange of the head cover  19  attached to the support table  67 . The flange of the head cover  19  is connected to the support table  67  by a threaded bolt  73 , and the stopper  72  is formed as a peripheral part of the bolt hole formed in the flange. Alternatively, the stopper  72  may consist of a protrusion protruding upward from the upper surface of the support table  67 , or a protrusion protruding forward from the intake side  18 A of the cylinder head  18 . When the second support member  51  is rotated by a predetermined angle around either one of the bolts  69 A and  69 B such that the left end portion  51 B of the second support member  51  moves rearward, the stopper  72  is brought into abutment with the projecting piece  71 , and thereby limits the angular movement of the second support member  51  (see FIG.  11 ). 
     As shown in  FIGS. 3 to 5 , the left end portion  51 B of the second support member  51  extends to the left while inclining upward with respect to the right end portion  51 A, and reaches the rear surface of the right chamber extension  42 B. A female threaded hole  74  is formed rearward on the front surface of the left end portion  51 B of the second support member  51 . The intake chamber member  42  and the second support member  51  are fastened to each other by a threaded bolt  75  that is passed through the bolt hole  66  of the right chamber extension  42 B from the front, and is threaded into the female threaded hole  74 . The left end portion  51 B of the second support member  51  and the right chamber extension  42 B are fastened to each other from the fore and aft direction with the threaded bolt  75 , and the right chamber extension  42 B is supported by the left end portion  51 B of the second support member  51  from the rear. As shown in  FIG. 9 , a coupling portion  76  for engaging a clip that retains a wire harness or a ground wire is formed in a part of the second support member  51 . The coupling portion  76  may be formed as a hole or a projection. 
     As shown in  FIGS. 3 and 5 , a trunk pipe mounting seat surface  77  is formed in a rear portion of the upstream portion  41 B of the trunk pipe  41 . The trunk pipe mounting seat surface  77  may be disposed close to the trunk pipe flange  46 , and may be connected to the trunk pipe flange  46 . The trunk pipe mounting seat surface  77  and the first support member  50  are connected to each other by a connecting member  80 . The connecting member  80  is a sheet metal member having a major plane facing vertically, and is and elongated in the fore and aft direction. The connecting member  80  is provided with a side flange  80 A bent upward along the right side edge of the main part of the connecting member  80  so as to define an L shaped cross section. The front end of the connecting member  80  is connected to the trunk pipe mounting seat surface  77  so as to be rotatable around an axial line orthogonal to the major plane of the trunk pipe mounting seat surface  77  via a vertically extending threaded bolt  81 , and the rear end of the connecting member  80  is connected to the connecting seat surface  82  of the trunk pipe mounting seat surface  77  so as to be rotatable around an axial line orthogonal to the major plane of the connecting seat surface  82  via a vertically extending threaded bolt  81 . 
     As shown in  FIGS. 3, 4 and 6 , the fuel delivery pipe  37  is disposed in the space defined between the intake side  18 A of the cylinder head  18  and the branch pipes  43 . In the present embodiment, the fuel delivery pipe  37  is disposed behind the trunk pipe  41  (which is in turn disposed behind the branch pipe  43 ), and in front of the intake side  18 A of the cylinder head  18 . The length of the fuel delivery pipe  37  in the lateral direction of the vehicle is substantially equal to the length of the intake chamber member  42  in the lateral direction of the vehicle, and the fuel delivery pipe  37  is disposed so as to align with the intake chamber member  42  in the lateral direction of the vehicle. Further, the fuel delivery pipe  37  is disposed between the first support member  50  and the second support member  51  with respect to the lateral direction of the vehicle. The upper end of the fuel delivery pipe  37  is disposed below the upper end of the first support member  50  and below the lower end of the second support member  51 . Further, the fuel delivery pipe  37  is disposed below both the left chamber extension  42 A and the right chamber extension  42 B. 
     As shown in  FIG. 6 , the intake manifold  31  is formed by combining a plurality of plastic members. In the present embodiment, the intake manifold  31  is provided with a main piece  85  constituting a rear portion thereof, a middle piece  86  constituting an intermediate portion with respect to the fore and aft direction and located behind the main piece  85 , and a port piece  87  constituting a front portion thereof. More specifically, the main piece  85  forms a portion of the branch pipes  43  on the cylinder head  18  side with respect to the lengthwise direction thereof, a rear portion of the intake chamber member  42 , and a rear portion of the trunk pipe  41 . The middle piece  86  forms an intermediate portion of the branch pipes  43  with respect to the lengthwise direction, a rear portion of the curved portion of the branch pipes  43 , a front portion of the intake chamber member  42 , and a front portion of the trunk pipe  41 . The port piece  87  constitutes the front portion of the curved portion of the branch pipes  43 . The main piece  85 , the middle piece  86 , and the port piece  87  are coupled to each other by vibration welding or the like, for example. The left side fastening seat surface  53  and the right chamber extension  42 B are formed in the main piece  85 . 
     The main piece  85  is formed so as to have a higher stiffness than the middle piece  86  and the port piece  87 . Specifically, when the intake manifold  31  is attached to the cylinder head  18 , the main piece  85  has a high resistance against a load from the front than the middle piece  86  and the port piece  87 . As a result, the main piece  85  deforms only after the port piece  87  and the middle piece  86  have deformed to a significant extent as a result of a load applied from the front side of the intake manifold  31 . The main piece  85 , the middle piece  86  and the port piece  87  may be given with suitable levels of stiffness by selecting the material, the shape and the thickness. 
     The behavior of the internal combustion engine  1  described above and the associated advantages of the internal combustion engine  1  at the time of a frontal crash are described in the following. When the vehicle  2  having the internal combustion engine mounted thereon makes a frontal crash, the bulkhead  4  and the radiator  5  are moved rearward by the load from the front, and the impact is transmitted to the intake manifold  31  positioned on the front side of the internal combustion engine  1  via the bulkhead  4  and the radiator  5 . Because the intake manifold  31  is connected to the engine main body  11  at the lower end portions of the branch pipes  43  (which are positioned in a lower part of the intake manifold  31 ) and at the intake chamber member  42  (which is positioned in an upper part of the intake manifold) via the first support member  50  and the second support member  51 , the intake manifold  31  is comparatively resistant against deformation at the time of a frontal crash. In particular, because the intake chamber member  42  extending in the lateral direction of the vehicle is attached to the engine main body  11  via the first support member  50  and the second support member  51  positioned in the respective lateral ends of the intake chamber member  42 , the resistance to deformation of the intake manifold  31  is enhanced. Thus, the fuel delivery pipe  37  positioned behind a vertically middle part of the intake manifold  31  or the branch pipes  43  and the trunk pipe  41  is favorably protected from the impact of a frontal crash. 
     Further, since the upstream portion  41 B of the trunk pipe  41  is coupled to the cylinder head  18  via the connecting member  80  and the first support member  50  so as to be resistant against an impact from the front, even when an impact of a frontal crash is applied to the part of the trunk pipe  41  adjoining the throttle valve  30  or the throttle valve  30  itself, the deformation of the trunk pipe  41  is minimized so that the rearward travel of the throttle valve  30  is minimized. 
     As shown in  FIGS. 10 a  and 10 b   , when the load applied to the front side of the branch pipes  43  at the time of a frontal crash of the vehicle  2  is so large that one of the bolts  69 A,  69 B is broken, the second support member  51  is caused to rotate around the other remaining bolt  69 A,  69 B until the projecting piece  71  abuts on the stopper  72 . As a result, a part of the load applied to the intake manifold  31  is absorbed by the fracture of one of the bolts  69 A and  69 B, and the friction between the second support member  51  and the support table  67  caused by the rotation of the second support member  51 . Also, the rearward travel of the intake manifold  31  is limited. As a result, the transmission of load from the intake manifold  31  to the fuel delivery pipe  37  can be favorably controlled. It may be configured such that when the projecting piece  71  has abutted on the stopper  72 , the intake manifold  31  connected to the second support member  51  is prevented from contacting the fuel delivery pipe  37 . Further, when a load is applied from the front, the middle piece  86  and the port piece  87  constituting the intake manifold  31 deform and collapse in such a manner that a part of energy of the load is absorbed, and this reduces the deformation of the main piece  85 . As a result, the intake manifold  31  is prevented from coming into contact with the fuel delivery pipe  37 . 
     As shown in  FIGS. 11 a  and 11 b   , when the load applied to the throttle valve  30  or the trunk pipe flange  46  at the time of a frontal crash of the vehicle  2  is large enough, the trunk pipe  41  is deformed or broken, the trunk pipe flange  46  and the throttle valve  30  that are joined to each other will move jointly rearward. At this time, the rearward movement of the trunk pipe flange  46  and the throttle valve  30  causes the connecting member  80  to pivot outward in the lateral direction of the vehicle around the bolt  81  (via which the connecting member  80  is coupled to the first support member  50 ), and the trunk pipe flange  46  and the throttle valve  30  are guided outward (leftward) in the lateral direction of the vehicle. When the trunk pipe flange  46  and the throttle valve  30  move rearward, the throttle valve  30  or the trunk pipe flange  46  abuts on the guide portion  65  of the first support member  50 , and is guided by the guide portion  65  in the laterally outward direction (leftward direction) of the vehicle. Since the connecting member  80  and the guide portion  65  guide the throttle valve  30  and the trunk pipe flange  46  outward (leftward) in the lateral direction of the vehicle, the throttle valve  30  and the trunk pipe flange  46  are prevented from coming into contact with the fuel delivery pipe  37 . Therefore, the need to provide an extra protection structure for the trunk pipe  41  and the throttle valve  30  can be eliminated. Also, due to deformation of the connecting member  80 , a part of the load at the time of the frontal crash can be absorbed. 
     In the above embodiment, since the first support member  50  serves both as a structural member and as a passage forming member defining a passage connecting the internal EGR passage  34  with the trunk pipe  41 , the number of component parts is reduced. The intake manifold  31  is provided with the left side fastening seat surface  53  extending from the intake chamber member  42  to the trunk pipe  41 , and is fastened to the first support member  50  at the left side fastening seat surface  53  over a relatively large mounting surface so that the intake manifold  31  is made resistant to deformation against a frontal crash. 
     In the foregoing embodiment, when the load at the time of a front collision is applied to the second support member  51  via the intake manifold  31 , one of the two bolts  69 A and  69 B may be broken. To predetermine which of the bolts  69 A and  69 B is to be broken, one of the bolts  69 A and  69 B may be provided with a lower mechanical strength than the other so that the pivot center for the second support member  51  at the time of a crash may be predetermined. The number of the bolts fastening the second support member  51  to the support table  67  is not limited to two, and may be three or more. In the foregoing embodiment, the rear end of the connecting member  80  is coupled to the first support member  50 , but may also be directly coupled to the cylinder head  18 . Further, the connecting member  80  may even be omitted. 
     Although the present invention has been described in terms of a preferred embodiment thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention.