Patent Publication Number: US-10323614-B2

Title: Supercharged engine

Description:
BACKGROUND 
     The present invention relates to a supercharged engine. 
     For example, JP2014-025476A discloses an engine having a supercharger and fuel system components (top injectors) all of which are disposed on a front side of an engine body, and the fuel system components are located above the supercharger to be spaced therefrom. 
     Incidentally, when a supercharger and a fuel system component, such as a fuel pump, are to be disposed on the same side of an engine body, in consideration of the influence of heat damage, etc., the two components may be disposed on an intake side of the engine body. If a vehicle equipped with the engine having such a structure receives a collision load, the supercharger may move in relation to the vehicle and come in contact with the fuel pump. Therefore, the fuel pump is required to be protected from the supercharger in order to ensure more safety. 
     For this, the fuel pump and the supercharger may be spaced apart from each other as described in JP2014-025476A, but such a structure is inconvenient for reducing the size of the engine. Especially when the fuel pump is disposed above the supercharger as in the structure of JP2014-025476A, the fuel pump approaches an engine hood by the spaced distance, which causes an inconvenience in that if the hood is deformed by the collision load, the deformed hood may contact the fuel pump. Even if the hood is sufficiently spaced apart from the fuel pump, the position of the hood from the ground becomes relatively high, which lowers aerodynamic characteristics of the vehicle, and as a result, a traveling resistance increases. 
     SUMMARY 
     The present invention is made in view of the above issues and aims to provide a supercharged engine having a supercharger and a fuel pump disposed on the same side of an engine body, which protects the fuel pump from the supercharger while achieving an engine size reduction. 
     According to one aspect of the invention, a supercharged engine is provided, which includes an engine body having cylinders, an intake passage disposed outside the engine body and connected to the cylinders via intake ports, a supercharger provided in the intake passage and spaced apart from an intake-side side surface of the engine body, the intake-side side surface being connected to the intake passage, and a fuel pump disposed on the intake-side side surface. 
     A portion of the intake passage constitutes an intervening part located between the supercharger and the engine body. The intervening part overlaps with the fuel pump in one of vertical and lateral directions of the engine body. 
     According to the structure, the supercharger is disposed such that, for example, an engine body side of the supercharger is spaced apart from the intake-side side surface of the engine body, and the intervening part, which is a part of the intake passage, is located between the supercharger and the engine body. Thus, for example, when the supercharger receives a collision load, an approach between the supercharger and the engine body is limited by the intervening part. 
     In addition, the intervening part overlaps with the fuel pump in one of the vertical and lateral directions of the engine body. Such an arrangement locates the fuel pump between the supercharger and the engine body when the engine is seen in the vertical or lateral directions, similar to the intervening part. Therefore, the limitation of the approach between the supercharger and the fuel pump by the intervening part prevents contact between the supercharger and the fuel pump, which leads to protecting the fuel pump from the supercharger. 
     Further, according to the above structure, the supercharger and the fuel pump may be brought close to each other in the vertical directions without separating them from each other as disclosed in JP2014-025476A, which is effective in reducing the size of the engine. 
     Thus, according to the above structure, the fuel pump is protected from the supercharger while reducing the size of the engine. 
     Moreover, according to the above structure, by having a portion of the intake passage as the intervening part, the fuel pump is protected from the supercharger without providing another member, which is effective in reducing the number of components of the engine. 
     The intervening part may be formed by a portion of the intake passage downstream of the supercharger. 
     The portion of the intake passage downstream of the supercharger includes a passage connected to the engine body. Disposing such a passage near the engine body is advantageous in reducing the size of the engine. 
     The intake passage may have a relay part constituting a passage downstream of the supercharger and upstream of the intervening part. The relay part may be connected to a part of the supercharger on a side opposite from the engine body. 
     According to the structure, when the collision load is received from the opposite side of the engine body, the load is added to the supercharger via the relay part. Since the relay part is a hollow member, it crushes according to the magnitude of the load. By crushing the relay part, the impact applied to the supercharger itself is subsided. Thus, a relative movement of the supercharger is reduced, which becomes advantageous in reliably protecting the fuel pump. 
     The supercharger may be fastened to the intervening part. 
     According to the structure, the intervening part supports the supercharger. Therefore, when the collision load is applied to the supercharger, the approach between the supercharger and the engine body is limited more reliably by the intervening part, which is advantageous in reliably protecting the fuel pump. 
     The supercharger may extend along the intake-side side surface. The supercharger may be fastened to the intervening part at two opposite end sides. 
     According to the structure, the supercharger is stably supported. Therefore, the approach between the supercharger and the engine body is stably limited, which is advantageous in reliably protecting the fuel pump. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a part of a structure of a supercharged engine according to one embodiment of the present invention. 
         FIG. 2  is a perspective view of the supercharged engine. 
         FIG. 3  is a front elevational view of the supercharged engine. 
         FIG. 4  is a plan view of the supercharged engine. 
         FIG. 5  is a perspective view illustrating the entire structure of an intake passage. 
         FIG. 6  is a partially-cutaway rear elevational view illustrating the structure of the intake passage. 
         FIG. 7  is a side view of the intake passage. 
         FIG. 8  is a horizontal cross-sectional view of the intake passage. 
         FIG. 9  is a vertical cross-sectional view of the intake passage. 
         FIG. 10  is a front elevational view illustrating a third passage and a distribution passage. 
         FIG. 11  is a horizontal cross-sectional view of the distribution passage. 
         FIG. 12  is a perspective view illustrating the distribution passage partially horizontally cut out. 
         FIG. 13  is a perspective view illustrating a structure of a fuel pump. 
         FIG. 14  is a vertical cross-sectional view illustrating arrangement of the fuel pump. 
         FIG. 15  is a view illustrating a positional relationship between the fuel pump and the distribution passage. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, some embodiments of a supercharged engine according to the present invention are described with reference to the accompanying drawings. Note that the following embodiments are merely examples. 
     Entire Structure of Engine 
       FIG. 1  illustrates a schematic structure of a supercharged engine (hereinafter, simply referred to as “the engine”) according to one embodiment of the present invention.  FIG. 2  is a perspective view of the engine.  FIG. 3  is an elevational view of the engine.  FIG. 4  is a plan view of the engine. The engine  1  is a gasoline engine mounted on a vehicle with a front-engine front-drive layout, and as illustrated in  FIGS. 1 to 3 , includes a mechanically-driven forced induction system (a so-called supercharger)  50 . 
     As illustrated in  FIG. 4 , the engine  1  includes four cylinders  18  arranged in line, and is a so-called transverse, inline four-cylinder engine in which the four cylinders  18  align in vehicle width (lateral) directions. Thus, in this embodiment, longitudinal directions of the engine which are in parallel to the arranged direction of the four cylinders  18  (cylinder line-up direction) substantially match with the vehicle lateral directions, and width directions of the engine substantially match with longitudinal directions of the vehicle. Hereinafter, unless otherwise specified, “front side” means one side in the engine width directions (an intake side of the engine, and in the transverse engine, a front side in the vehicle longitudinal directions), and “rear side” means the other side in the engine width directions (an exhaust side of the engine, and in the transverse engine, a rear side in the vehicle longitudinal directions). Further, “left side” means one side in the engine longitudinal directions (one side in the cylinder line-up direction, and in the transverse engine, a left side in the vehicle lateral directions), and “right side” means the other side in the engine longitudinal directions (the other side in the cylinder line-up direction, and in the transverse engine, a right side in the vehicle lateral directions). Moreover, “upper side” means one side in engine vertical directions perpendicular to the engine width directions and the engine longitudinal directions, and “lower side” means the other side in the engine vertical directions. 
     As illustrated in  FIG. 1 , the engine  1  mainly includes an engine body  10  having the four cylinders  18  (only one cylinder is illustrated in  FIG. 1 ), an intake passage  30  disposed on the front side (outside) of the engine body  10  and connected to the respective cylinders  18  via intake ports  16 , an exhaust passage (only illustrated in  FIG. 1 )  40  disposed on the rear side of the engine body  10  and connected to the respective cylinders  18  via exhaust ports  17  (so-called front-intake, rear-exhaust engine). The supercharger  50  is disposed in the intake passage  30 . As illustrated in  FIGS. 2 and 3 , the intake side (front side) of the engine body  10  is also provided with, in addition to the intake passage  30 , a drive pulley  53  for the supercharger  50 , an alternator  91  for generating an alternating current used in an electric system, an air compressor  92  for air conditioning, a starter motor  93  for driving the engine body  10  until a complete combustion is performed at the time of an engine start, a fuel pump  96  constituting a fuel supply system  95 , etc. 
     The engine body  10  combusts inside the cylinders  18  a mixture gas containing the intake air supplied from the intake passage  30  and fuel. For example, the engine body  10  includes a cylinder block  11  provided with the four cylinders  18 , a cylinder head  12  assembled on the cylinder block  11 , and an oil pan  13  disposed below the cylinder block  11  and storing a lubricant. A reciprocatable piston  14  coupled to a crankshaft  15  via a connecting rod  141  is fitted into each of the cylinders  18 . 
     In the cylinder block  11 , the four cylinders  18  are arranged in line. In the following description, the four cylinders  18  illustrated in  FIG. 4  may be referred to as the first cylinder  18   a , the second cylinder  18   b , the third cylinder  18   c , and the fourth cylinder  18   d  in this order from the right side in the cylinder line-up direction. 
     In the cylinder head  12 , two intake ports  16  and two exhaust ports  17  are formed for each of the cylinders  18 , each of the intake ports  16  is provided with an intake valve  21  for opening and closing the intake port  16  at the cylinder  18  side and each of the exhaust ports  17  is provided with an exhaust valve  22  for opening and closing the exhaust port  17  at the cylinder  18  side.  FIG. 4  illustrates a structure of the intake ports  16  of the second cylinder  18   b . For example, the cylinder head  12  of this embodiment is provided, for each of the cylinders  18 , with two intake apertures  16   a  opening to the cylinder  18  and the two intake ports  16  attached to a downstream end (specifically, independent passages  72 ) of the intake passage  30  and connecting the downstream end to the intake apertures  16   a . Upstream ends  16   b  of the intake ports  16  open at an attaching surface  10   a  (described later) and are arranged in the cylinder line-up direction. A distribution passage  70  extends in the cylinder line-up direction to communicate with the upstream ends  16   b  of the intake ports  16  of the respective cylinders  18  and to cover the upstream ends  16   b . The intake valves  21  for opening and closing the eight intake ports  16  are driven by an intake camshaft provided to the cylinder head  12 . For example, when the intake camshaft rotates, the rotational force acts on upper end portions of the intake valves  21  via cams of the intake camshaft to drive the intake valves  21  to open and close the intake apertures. The corresponding components on the exhaust side are also driven in a similar manner. 
     An injector  98  for injecting the fuel supplied from a fuel tank into the cylinder  18  is attached to the cylinder head  12  for each cylinder  18 . The fuel tank is connected to the injectors  98  by a fuel supply path. The fuel supply path is provided with a fuel supply system  95  including the fuel pump  96  and a common rail  97 , and for supplying the fuel to the injectors  98  at a relatively high pressure. The fuel pump  96  sends the fuel from the fuel tank to the common rail  97 , and the common rail  97  stores the sent fuel at a relatively high pressure. When the injectors  98  open, the fuel stored in the common rail  97  is injected from injection ports of the injectors  98 . 
     The intake passage  30  allows externally introduced intake air (fresh air) to pass therethrough and supplies it to the cylinders  18  of the engine body  10 . For example, an air cleaner  31  (only illustrated in  FIG. 1 ) for purifying the intake air introduced externally, a throttle valve  32  for adjusting a flow rate of the intake air passing therethrough, the mechanically driven supercharger  50  for compressing the intake air, and an intercooler  60  for adjusting a temperature of the intake air, are disposed in the intake passage  30  in this order from an upstream side of the intake flow. 
     The downstream end of the intake passage  30  is formed by the distribution passage  70  for supplying the intake air to the cylinders  18 . The distribution passage  70  has a surge tank  71  for temporarily storing air, and the independent passages  72  for distributing the air stored in the surge tank  71  to the cylinders  18 , respectively. 
     Further, the intake passage  30  has passages to connect various parts with each other. The passages include a first passage  34  for leading the intake air purified by the air cleaner  31  to the supercharger  50 , a second passage  35  for leading the intake air compressed by the supercharger  50  to the intercooler  60 , and a third passage  36  for leading the air passed through the intercooler  60  to the distribution passage  70 . 
     The intake passage  30  is branched on the upstream side of the supercharger  50  and merges again on the downstream side of the supercharger  50  and the intercooler  60 . For example, the intake passage  30  is provided with a bypass passage  80  connecting a portion of the intake passage  30  between the throttle valve  32  and the supercharger  50  with a portion of the intake passage  30  between the intercooler  60  and the distribution passage  70 . A bypass valve  81  for opening and closing the bypass passage  80  is disposed in the bypass passage  80 . 
     The exhaust passage  40  discharges exhaust gas generated in the cylinders  18  to the outside thereof. For example, an upstream portion of the exhaust passage  40  is formed by an exhaust manifold (not illustrated) having independent passages extending toward the cylinders  18  and connected to external ends of the exhaust ports  17 , and a manifold section where the independent passages are collected together. Exhaust purifying catalysts  41  and  42  for purifying hazardous components within the exhaust gas are connected to the exhaust passage  40  on the downstream side of the exhaust manifold. 
     Hereinafter, the structure of the intake side (front side), i.e., the intake system of the engine  1 , particularly the three-dimensional structure of the intake passage  30 , and the arrangement of peripheral components thereof are described. 
     Intake System Structure 
       FIG. 5  is a perspective view illustrating the structure of the intake passage  30 .  FIG. 6  is a partially-cutaway rear elevational view illustrating the structure of the intake passage  30 .  FIG. 7  is a side view of the intake passage  30 .  FIG. 8  is a horizontal cross-sectional view of the intake passage  30 .  FIG. 9  is a vertical cross-sectional view of the intake passage  30  seen in the crankshaft axial directions. 
     The various parts constituting the intake passage  30  are all disposed on the front side of the engine body  10 , more specifically, on a side (in front) of a front surface  10   a  of the engine body  10  (see  FIGS. 2 to 4 and 12 ). Hereinafter, the front surface  10   a  which is the intake-side side surface of the engine body  10  (specifically, a side surface of the engine body  10  to which the intake passage  30  is connected) is referred to as the attaching surface  10   a . As illustrated in  FIG. 3  etc., the attaching surface  10   a  is formed by the cylinder block  11  and a front surface of the cylinder head  12 . As described later, the supercharger  50  is attached to the attaching surface  10   a  with a given space  11 , thus a gap is provided between a rear surface of the supercharger  50  and the attaching surface  10   a . The first passage  34  extends in the cylinder line-up direction on the left side of the supercharger  50 , and is connected to a left end of the supercharger  50 . Further, the intercooler  60  is adjacently disposed on the vertically lower side (direction of gravity) of the supercharger  50  and is disposed with a given space I 2  from the attaching surface  10   a , similar to the supercharger  50 . The intercooler  60  is also disposed in parallel to the fuel pump  96 . The second passage  35  vertically extends to connect a front part of the supercharger  50  with a front part of the intercooler  60 . The distribution passage  70  is located in the gap between the supercharger  50  and the attaching surface  10   a , and the third passage  36  extends along the gap between the part extending from the supercharger  50  to the intercooler  60  and the attaching surface  10   a  so as to connect the distribution passage  70  with the intercooler  60 . The bypass passage  80  extends downwardly from an intermediate position of the first passage  34  and then extends inwardly (rightwardly) toward the engine body  10  to be connected to a left part of the intercooler  60 . 
     Next, the structure and arrangement of the various parts are described in detail. 
     The first passage  34  is generally formed in a tubular shape extending in the left-and-right directions, and an upstream end (left end) thereof is formed by a throttle body  34   a  built therein with the throttle valve  32 . As illustrated in  FIGS. 3 to 6 , etc., the throttle body  34   a  is made of metal, formed in a short cylindrical shape, and located at a position leftward and forward of the attaching surface  10   a  in a posture opening to the left and right at two opposite ends. The upstream end (left end) of the throttle body  34   a  is connected to the air cleaner  31  via a given passage (not illustrated), and a downstream end (right end) of the throttle body  34   a  is connected to a first passage main body  34   b  constituting another part of the first passage  34 . 
     As illustrated in  FIGS. 3 to 6 , the first passage main body  34   b  connects the throttle body  34   a  with the supercharger  50 . For example, the first passage main body  34   b  is made of resin, formed in a long tubular shape, and arranged to open to the left and right at two opposite ends. The first passage main body  34   b  is coaxially disposed with the throttle body  34   a , on the front side of an upper left part of the attaching surface  10   a . For example, as illustrated in  FIG. 6 , the diameter of the first passage main body  34   b  increases toward the inner side in the cylinder line-up direction (toward the right side). An upstream end (left end) of the first passage main body  34   b  is connected to the downstream end of the throttle body  34   a , and a downstream end (right end) of the first passage main body  34   b  is connected to a suction port of the supercharger  50 . 
     The first passage main body  34   b  is formed with a branch part  34   c  branching into the bypass passage  80 . As illustrated in  FIG. 6 , the branch part  34   c  is formed in a lower surface of an upstream portion of the first passage main body  34   b , and is connected to an upstream end of the bypass passage  80 . As illustrated in  FIGS. 4 to 6 , etc., the branch part  34   c  is disposed at a position on the outer side (left side) in the vehicle width directions, of the supercharger  50 , the intercooler  60 , the eight intake ports  16 , and the distribution passage  70  connected to the intake ports  16 . 
     Therefore, the intake air purified by the air cleaner  31  and flowed into the first passage  34  passes through the throttle valve  32 , and then either is sucked into the supercharger  50  from the downstream end of the first passage main body  34   b  (see an arrow A 1  in  FIG. 6 ) or flows into the bypass passage  80  via the branch part  34   c  at the intermediate position of the first passage main body  34   b.    
     The supercharger  50  is configured as a roots-type supercharger. For example, the supercharger  50  has a pair of rotors (not illustrated) having a rotation shaft extending in the cylinder line-up direction, a casing  52  accommodating the rotors, and the drive pulley  53  for rotating the rotors. The supercharger  50  is drivably coupled to the crankshaft  15  via a drive belt (not illustrated) wrapped around the drive pulley  53 . 
     The casing  52  extends along the attaching surface  10   a  in the left-and-right directions, and forms an accommodation space for the rotors and a flow path of the intake air in the supercharger  50 . For example, the casing  52  is made of metal, formed in a rectangle tubular shape opening at a left end and a front surface, and as illustrated in  FIG. 4  etc., the casing  52  has the given space  11  (see  FIG. 9 ) from a position above a substantially center of the attaching surface  10   a  in the left-and-right directions, and is coaxially disposed with the first passage  34 . A left end part of the casing  52  in its longitudinal directions is formed with a suction port for sucking the intake air to be compressed by the rotors, and the downstream end (right end) of the first passage  34  is connected to the suction port. On the other hand, as illustrated in  FIG. 9 , the front surface (the side opposite from the engine body  10 ) of the casing  52  is formed with a discharge port  52   b  for discharging the intake air compressed by the rotors, and an upstream end of the second passage  35  is connected to the discharge port  52   b.    
     Here, as illustrated in  FIGS. 4 to 6 , the supercharger  50  is fastened to the distribution passage  70  at both end sides in longitudinal directions (left and right end sides). For example, a right end side bracket  52 R having a bolt insertion hole is provided to protrude in a right end part of a rear surface (a side surface on the engine body side) of the casing  52 . A left end side bracket  52 L having a similar structure as the right end side bracket  52 R is provided to protrude in a left end part of the rear surface of the casing  52 . The bolt insertion holes of both the right and left end side brackets  52 R and  52 L allow bolts to pass therethrough from the upper side (see also  FIG. 14 ). 
     Additionally, as illustrated in  FIGS. 5 and 9 , the supercharger  50  is also fastened to the third passage  36 . For example, a pair of center brackets  52 C are provided to protrude in substantially a center part of the rear surface of the casing  52  in the left-and-right directions, and spaced apart from each other in the left-and-right directions. Each center bracket  52 C has a bolt insertion hole. The bolt insertion hole of each center bracket  52 C is formed so that a bolt is inserted thereinto in the left-and-right directions. One of the brackets  52 C supports a base end portion of the inserted bolt and the other bracket  52 C supports a tip portion of the same bolt. 
     The drive pulley  53  rotates the rotors accommodated in the casing  52 . For example, the drive pulley  53  is formed into a shaft protruding from a right end of the casing  52  and extending substantially coaxially with the first passage  34  and the casing  52 . A drive belt is wrapped around a tip part of the drive pulley  53 , and as described above, drivably couples the crankshaft  15  to the supercharger  50 . 
     Therefore, during operation of the engine  1 , an output from the crankshaft  15  is transmitted via the drive belt and the drive pulley  53  to rotate the rotors. The rotation of the rotors causes compression of the intake air sucked from the first passage  34  and discharge thereof from the discharge port  52   b . The discharged intake air flows into the second passage  35  disposed on the front side of the casing  52 . 
     The second passage  35  connects the supercharger  50  with the intercooler  60  as illustrated in  FIGS. 2, 3, 9, 14 , etc. As described above, since the supercharger  50  and the intercooler  60  are disposed vertically adjacent to each other, the second passage  35  of this embodiment extends in the up-and-down directions. The second passage  35  is formed such that both upper and lower ends thereof curve to the engine body side (rear side). An upper end of the second passage  35  is connected to the front part (discharge port  52   b ) of the casing  52  of the supercharger  50 , and a lower end thereof is connected to the front part of the intercooler  60 . For example, as illustrated in  FIGS. 2 and 9 , the second passage  35  is formed as a curved tube having a flat shape in the left-and-right directions, is made of resin, extending downwardly from the discharge port  52   b  of the casing  52  while curving to convex to the opposite side (front side) of the engine body  10 , and is connected to the front part of the intercooler  60 . Further, a portion of the second passage  35  near its upper end extends to cover a part of a front surface of the supercharger  50 , and thus the upper end of the second passage  35  forms a space in front of the supercharger  50 . Similarly, a portion of the second passage  35  near its lower end extends to cover a part of a front surface of the intercooler  60 , and thus the lower end of the second passage  35  forms a space in front of the intercooler  60 . Note that the second passage  35  is a portion of the intake passage  30  downstream of the supercharger  50  and upstream of the distribution passage  70 , and constitutes the “relay part” of this embodiment. 
     Thus, as indicated by an arrow A 2  in  FIG. 9 , the intake air which flows from the supercharger  50  into the second passage  35  flows forwardly from the supercharger  50 , downwardly along the second passage  35 , and then rearwardly to the intercooler  60 . The intake air passed through the second passage  35  flows into the intercooler  60  from the front side. 
     Further, since the second passage  35  connects the supercharger  50  with the intercooler  60 , a relative movement of the supercharger  50  and the intercooler  60  to each other in the up-and-down directions is limited. 
     As illustrated in  FIGS. 7, 8 , etc., the intercooler  60  is configured as a water-cooled intercooler, and includes a core  61  having an intake air cooling function, a core connecting part  62  supporting a water supply pipe  62   a  for introducing cooling water into the core  61  and supporting a drain pipe  62   b  for leading out the cooling water from the core  61 , and a cooler housing  63  for accommodating the core  61 . The core connecting part  62  is attached to a side part of the core  61 . 
     Note that as illustrated in  FIG. 6 , a dimension Wi of the intercooler  60  in width directions of the intercooler  60  (left-and-right directions) is shorter than a dimension Ws of the supercharger  50  in the width directions. 
     As illustrated in  FIGS. 8, 9 , etc., the core  61  is formed in a cuboid shape and arranged so that one side surface (rear surface) thereof faces the attaching surface  10   a . A front surface of the core  61  constitutes an entrance surface for the intake air, whereas a rear surface of the core  61  forms an exit surface for the intake air. Both of these surfaces are largest among all surfaces of the core  61 . A plurality of water tubes are arranged in the core  61 , and each of the water tubes is formed in a flat tubular shape by a thin plate member. Corrugated fins are connected to an outer wall surface of each water tube, for example, by brazing. With such a structure, the coolant introduced from the water supply pipe  62   a  is supplied to each water tube to cool high-temperature intake air, and the coolant warmed up by cooling the intake air is led out from each water tube via the drain pipe  62   b . Additionally, by providing the corrugated fins, the surface area of each water tube is increased to improve the heat radiation effect. 
     As illustrated in  FIGS. 6 to 8 , the core connecting part  62  is a thin rectangular plate member attached to a right surface of the core  61 , and connects the water supply pipe  62   a  and the drain pipe  62   b  to the water tubes. The core connecting part  62  defines a right surface of the intercooler  60  and a right-side wall of an accommodation space S 1 . 
     The cooler housing  63  forms the accommodation space S 1 , a flow path interposed between the second passage  35  and the third passage  36  in the intake passage  30 , and a flow path where the bypass passage  80  and the intake passage  30  merges with each other. For example, the cooler housing  63  is disposed below the casing  52  of the supercharger  50  with the given space I 2  (see  FIG. 9 ) from the attaching surface  10   a  similarly to the casing  52 . Further, the cooler housing  63  is formed in a substantially box shape, and a rear surface thereof faces the attaching surface  10   a . The cooler housing  63  is provided with a housing main body  64  defining the accommodation space S 1 , and a merging part  65  connected to a downstream end of the bypass passage  80  and where the intake air passed through the bypass passage  80  merges with the intake air cooled by the core  61 . 
     The housing main body  64  is formed in a thin rectangular box shape extending along the attaching surface  10   a  and opening at front and rear surfaces. The downstream end of the second passage  35  is connected to a front-surface opening  64   a , and an upstream end of the third passage  36  is connected to a rear-surface opening  64   b . Further, the housing main body  64  also opens at a right surface. A right-surface opening  64   c  is formed as an insertion port from which the core  61  is inserted to be accommodated inside the housing main body  64 , and is closed by the core connecting part  62 . The accommodation space S 1  is defined by a top wall  64   d , a bottom wall  64   e , and a left side wall  64   f  of the housing main body  64 , and the core connecting part  62 . As described below, the bottom wall  64   e  and the left side wall  64   f  also define an inner wall of the merging part  65 . 
     Thus, as indicated by an arrow A 3  in  FIGS. 8 and 9 , the intake air passed through the second passage  35  flows into the housing main body  64  from the front-surface opening  64   a , and flows rearwardly. Here, the intake air passes through the core  61  while being cooled by the cooling water supplied to the water tubes. The cooled intake air flows out of the rear-surface opening  64   b  of the housing main body  64  and into the third passage  36 . 
     As illustrated in  FIGS. 5, 6, 8, and 9 , the merging part  65  has an inlet portion  66  to which the downstream end of the bypass passage  80  is connected, and a communicating portion  67  for leading the intake air entered from the inlet portion  66  into the space S 2  which is located downstream (rear side) of the accommodation space S 1  in the cooling housing  63 . The merging part  65  of this embodiment is made of resin. 
     As illustrated in  FIGS. 5, 6 , etc., the inlet portion  66  is provided in a lower part of a left surface of the intercooler  60  and is formed as a tubular portion protruding leftwardly from the lower part. An upstream end (left end) of the inlet portion  66  opens leftwardly and is connected to the downstream end of the bypass passage  80 . 
     The communicating portion  67  extends along an outer surface of the left side wall  64   f  of the housing main body  64  and an outer surface of the bottom wall  64   e , and is defined as a passage communicating with the space S 2  which is located downstream of the core  61  in the intercooler  60 . For example, a first communicating portion  67   a  extending in the up-and-down directions and communicating with a downstream end (right end) of the inlet portion  66  and a left section of the space S 2  located rearward of the core  61  is formed in the communicating portion  67  on the outer side (left side) of the left side wall  64   f . Further, a second communicating portion  67   b  extending in the left-and-right directions and communicating with a lower end of the first communicating portion  67   a  and a bottom section of the space S 2  is formed in the communicating portion  67  on the outer side (lower side) of the bottom wall  64   e . The first and second communicating portions  67   a  and  67   b  lead the intake air entered from the inlet portion  66  into the space S 2 . Note that the second communicating portion  67   b  partially bulges downwardly as illustrated in the vertical cross section in  FIG. 9 . This bulge enables a reduction of airflow resistance caused when the intake air flows through the second communicating portion  67   b.    
     Thus, as indicated by an arrow A 6  in  FIG. 6 , the intake air passed through the bypass passage  80  flows into the merging part  65  via the inlet portion  66 , and reaches the communicating portion  67 . Then the intake air flows to the rear side of the core  61  along the outer surfaces of the left side wall  64   f  and the bottom wall  64   e  of the housing main body  64 , and then merges in the space S 2 , with the intake air passed through the core  61 . For example, the intake air that has reached the communicating portion  67  from the bypass passage  80  flows downwardly along the first communicating portion  67   a  and then flows rightwardly along the second communicating portion  67   b , so as to merge in the space S 2  by flowing rightwardly along the second communicating portion  67   b  (see an arrow A 8  in  FIGS. 6 and 9 ) or flowing rearwardly along the first communicating portion  67   a  (see an arrow A 7  in  FIG. 8 ). 
     The bypass passage  80  is formed in a curved tubular shape extending rightwardly after extending downwardly, the upstream end (upper end) thereof is formed by a valve body  80   a  built therein with the bypass valve  81 , and a portion thereof downstream of the valve body  80   a  is formed by a bypass passage main body  80   b  formed as a curved tube. 
     As illustrated in  FIGS. 3 to 4 , the valve body  80   a  is made of metal, formed in a short cylindrical shape, and arranged below the first passage  34  and on the front side of a position near a left end of the attaching surface  10   a , to open in the up-and-down directions at both ends. An upstream end (upper end) of the valve body  80   a  is connected to the branch part  34   c  of the first passage  34 , and a downstream end (lower end) of the valve body  80   a  is connected to the upstream end of the bypass passage main body  80   b.    
     The bypass passage main body  80   b  connects the branch part  34   c  of the first passage  34  to the merging part  65  of the cooler housing  63 . For example, the bypass passage main body  80   b  is formed as an elbow-shaped curved tube made of resin, and adjacently arranged on the left side of the intercooler  60  at a position downward of the first passage  34  and the valve body  80   a , so as to open upwardly and rightwardly. Similar to the valve body  80   a , the bypass passage main body  80   b  is disposed on the front side of a position near the left end of the attaching surface  10   a . The upstream end (upper end) of the bypass passage main body  80   b  is connected to the downstream end of the valve body  80   a , and a downstream end (right end) of the bypass passage main body  80   b  is connected to the inlet portion  66  of the merging part  65 . 
     Thus, as indicated by the arrow A 6  in  FIG. 6 , the intake air branched from the first passage  34  and flowed into the bypass passage  80  passes through the bypass valve  81  built in the valve body  80   a , and flows into the bypass passage main body  80   b . The air flowed into the bypass passage main body  80   b  flows downwardly then rightwardly, and further flows into the merging part  65  via the inlet portion  66 . 
       FIG. 10  is a front elevational view illustrating the third passage  36  and the distribution passage  70 .  FIG. 11  is a horizontal cross-sectional view of the distribution passage  70 .  FIG. 12  is a perspective view illustrating the distribution passage  70  partially horizontally cut out. 
     The third passage  36  is a resin member integrally formed with the distribution passage  70  and connects the intercooler  60  with the distribution passage  70  as illustrated in  FIGS. 6 and 9 . For example, the third passage  36  has, in the following order from the upstream side, a manifold portion  36   a  fastened to the cooler housing  63  and into which the intake air passed through the intercooler  60  and the intake air passed through the bypass passage  80  flow, and an introducing portion  36   b  leading to the distribution passage  70  the intake air collected in the manifold portion  36   a . As illustrated in  FIGS. 10 to 12 , a supporting part  37  which is fastened to the center brackets  52 C of the casing  52  is provided on a front surface of the third passage  36  near the boundary between the manifold portion  36   a  and the introducing portion  36   b.    
     As illustrated in  FIG. 8 , the manifold portion  36   a  is formed in a box shape opening at a front (i.e., cooler housing  63  side) surface and having a short dimension in the front-and-rear directions, and the opened portion is connected to the rear-surface opening  64   b  of the housing main body  64 . As illustrated in  FIG. 9  etc., the manifold portion  36   a  is located between the rear surface of the housing main body  64  and the attaching surface  10   a  of the engine body  10 . Further, a rear surface of the manifold portion  36   a  is connected to an upstream end of the introducing portion  36   b.    
     The introducing portion  36   b  is formed as a curved tube extending substantially in the up-and-down directions, connected to the rear surface of the manifold portion  36   a  at an upstream end, and also connected to a lower center portion  71   a  of the surge tank  71  at a downstream end (see  FIGS. 11 and 12 ). As illustrated in  FIG. 9  etc., the introducing portion  36   b  extends along the gap between the part extending from the rear surface of the manifold portion  36   a  to the rear surface of the casing  52  and the attaching surface  10   a  of the engine body  10 . 
     For example, as illustrated in  FIG. 10 , an upstream section of the introducing portion  36   b  (corresponding to a section P 1  in  FIG. 10 ) extends obliquely rightwardly and upwardly from the connected position with the manifold portion  36   a , and a downstream section of the introducing portion  36   b  (corresponding to a section P 2  in  FIG. 10 ) extends right upwardly from an upper end of the upstream portion to the connected position with the surge tank  71 . 
     As illustrated in  FIG. 9 , etc., the supporting part  37  allows a bolt to pass therethrough in the left-and-right directions, and supports the inserted bolt from the lower side. When the supercharger  50  is attached at a given attachment position, the center brackets  52 C of the casing  52  interpose the supporting part  37  therebetween in the left-and-right directions. By fitting a single bolt into the bolt insertion hole of the center brackets  52 C and the supporting part  37  in this state, the casing  52  (as a result, the supercharger  50 ) is fastened to the third passage  36 . Thus, the third passage  36  supports the supercharger  50  via the fitted bolt. The third passage  36  constitutes the “intervening part” of this embodiment. 
     As illustrated in  FIGS. 4 to 6 and 10 to 12 , the distribution passage  70  has the surge tank  71  extending in the left-and-right directions, and the eight independent passages  72  formed on the rear side of the surge tank  71  and connected to the intake ports  16 , respectively. As illustrated in  FIG. 4 , etc., the distribution passage  70  is located between the supercharger  50  and the engine body  10 , for example, between the rear surface of the casing  52  and the attaching surface  10   a  of the engine body  10 . The distribution passage  70  constitutes the “intervening part” of this embodiment. A right end side fastening part  71 R to which the right end side bracket  52 R provided to the casing  52  of the supercharger  50  is fastened and a left end side fastening part  71 L to which the left end side bracket  52 L is fastened are provided to a side surface of the surge tank  71  opposite from the engine body  10  (the front surface of the surge tank  71 ). 
     The surge tank  71  extends in the left-and-right directions from the disposed position of the intake port  16  corresponding to the first cylinder  18   a  to the disposed position of the intake port  16  corresponding to the fourth cylinder  18   d , and is formed in a bottomed cylindrical shape closed on both ends in the left-and-right directions. Further, as illustrated in  FIG. 12 , the downstream end of the introducing portion  36   b  is connected to a lower surface of the surge tank  71 . For example, an extending direction of a downstream portion of the introducing portion  36   b  perpendicularly intersects with the extending direction of the surge tank  71 . The downstream portion of the introducing portion  36   b  is connected to a center part of the lower surface of the surge tank  71  in the left-and-right directions. In the surge tank  71 , a dimension D 1  from the connected part with the introducing portion  36   b  to one end in the left-and-right directions, is equal to a dimension D 2  from the connected part to the other end in the left-and-right directions (D 1 =D 2 ). By this structure, the distribution performance of the intake air is secured, which is advantageous in reducing the difference in intake efficiency between the cylinders. 
     The eight independent passages  72  are formed in an engine-body-side surface (rear surface) of the surge tank  71 . Each of the eight independent passages  72  is formed as a passage extending in the front-and-rear directions, communicates with the space inside of the surge tank  71  at one end, and opens to the engine body side (rear side) at the other end. The eight independent passages  72  are located at positions corresponding to the eight intake ports  16 , respectively. By fastening the distribution passage  70  to the cylinder block  11 , the distribution passage  70  becomes communicable with the cylinders  18  via the intake ports  16 . 
     Thus, the intake air flowed into the third passage  36  from the intercooler  60  passes through the manifold portion  36   a  (see an arrow A 4  in  FIG. 9 ), and then flows obliquely rightward and upward along the upstream section (section P 1 ) of the introducing portion  36   b , and flows directly upward along the downstream section (section P 2 ) of the introducing portion  36   b . Then, the intake air further flows into the substantially center of the surge tank  71  in the left-and-right directions, is temporarily accumulated in the surge tank  71 , and is then supplied from the independent passages  72  to the respective cylinders  18  (see an arrow A 5  in  FIG. 9 ). 
     Here, as illustrated in  FIGS. 4, 14 , etc., each of the right and left end side fastening parts  71 R and  71 L is provided with a bolt insertion portion extending in cylinder axial directions (up-and-down directions). When the supercharger  50  is disposed at the above-described attachment position, the right end side bracket  52 R is placed on the right end side fastening part  71 R, and the left end side bracket  52 L is placed on the left end side fastening part  71 L. In this state, a bolt is fitted into the bolt insertion hole of the right end side bracket  52 R and the bolt insertion portion of the right end side fastening part  71 R, and another bolt is fitted into the bolt insertion hole of the left end side bracket  52 L and the bolt insertion portion of the left end side fastening part  71 L, so that the casing  52  (as a result, the supercharger  50 ) is fastened to the distribution passage  70 . Thus, the supercharger  50  is supported by the distribution passage  70  via the fitted bolts. 
     In the intake passage  30  of this embodiment, the intake air purified by the air cleaner  31  flows into the first passage  34 . Here, whether to flow the intake air into the bypass passage  80  is switchable by opening and closing the bypass valve  81 . When the bypass valve  81  is closed, the intake air flowed into the first passage  34  is led from the first passage  34  to the supercharger  50  and compressed within the supercharger  50 . The compressed intake air is discharged to the second passage  35 , is cooled while passing through the core  61  of the intercooler  60 , and then reaches the third passage  36 . On the other hand, when the bypass valve  81  is opened, the intake air bypasses the supercharger  50  and the core  61  by passing through the bypass passage  80  branched from the intermediate position of the first passage  34 . The intake air passed through or bypassed the supercharger  50  etc. passes through the space S 2 , is led to the distribution passage  70  via the third passage  36 , and is distributed to the eight independent passages  72 . 
     Here, as indicated by the arrow A 4  in  FIG. 6 , the intake air led to the distribution passage  70  via the bypass passage  80  flows along a flow path curving in a downwardly convex shape. This flow path is effective in reducing the flow resistance of the intake air. 
     Next, the arrangement of peripheral parts of the intake passage  30 , particularly the alternator  91 , the air compressor  92 , the starter motor  93 , and the fuel pump  96  described above, is described. 
     As illustrated in  FIGS. 2 to 3 , near the right end (the left end in the sheets of  FIGS. 2 and 3 ) of the attaching surface  10   a , the drive pulley  53  constituting the supercharger  50 , the alternator  91 , and the air compressor  92  are arranged in this order from the upper side. For example, the alternator  91  is adjacently disposed on the right side of the intercooler  60 , at a position near the right end of the front surface of the cylinder block  11 . Further, the air compressor  92  is disposed at a height position between the alternator  91  and the oil pan  13 . Both of the alternator  91  and the air compressor  92  are drivably coupled to the crankshaft  15  via the drive belt, and are operated by the drive force transmitted by the drive belt. 
     The starter motor  93  is disposed below the intercooler  60 . For example, the starter motor  93  is arranged with its drive shaft oriented in the left-and-right directions, and as illustrated in  FIG. 6  etc., is located below the core  61  via the second communicating portion  67   b . The starter motor  93  is drivably coupled to the crankshaft  15  via an exclusive gear system, and drives the crankshaft  15  at the time of starting the engine  1 . 
     The fuel pump  96  is fastened to be located on the same side of the engine  1  as various parts including the supercharger  50 , that is, on the attaching surface  10   a  side. The fuel pump  96  of this embodiment is a plunger pump, has a cam (not illustrated) for driving the pump, and the cam is drivably coupled to the crankshaft  15  via an exclusive timing chain. The cam driven by the crankshaft  15  reciprocates the plunger via a tappet to pump the fuel. To drive the fuel pump  96 , the intake camshaft may be used as conventionally known. However, with such a structure, if also a VVT (Variable Valve Timing) of the intake system is driven by the intake camshaft, the torque for driving the VVT becomes insufficient by the amount of torque required for driving the fuel pump  96 , and normal operation of the VVT may become impossible. Driving the fuel pump  96  with the crankshaft  15  as in this embodiment achieves both the drive of the fuel pump  96  and the drive of the VVT by the intake camshaft, and is advantageous when using a high-pressure fuel pump as the fuel pump  96 . Thus, a fuel injection amount is finely controlled, which reduces a fuel consumption of the engine. Additionally, with such a structure, the fuel pump  96  may be attached to a side surface of the engine body  10 . In this case, since heat damage may be concerned if the side surface to attach the fuel pump  96  to is on the exhaust side, the fuel pump  96  is disposed on the intake side, near the intake-side side surface  10   a.    
       FIG. 13  is a perspective view illustrating a structure of the fuel pump  96 .  FIG. 14  is a vertical cross-sectional view illustrating the arrangement of the fuel pump  96  seen in the crankshaft axial directions. As illustrated in  FIG. 13 , the fuel pump  96  is provided, in the following order, with a pump main body  96   a  having a suction port  961  and a discharge port  962  for the fuel and formed with a channel through which the fuel passes, a tappet accommodating part  96   b  accommodating the tappet to be movable in the up-and-down directions, and a cam accommodating part  96   c  rotatably accommodating the cam. The fuel pump  96  of this embodiment is attached so that the pump main body  96   a  is located on the upper side and the cam accommodating part  96   c  is located on the lower side. Further as illustrated in  FIG. 14 , the fuel pump  96  is attached to be located between the part extending from the intercooler  60  to supercharger  50  and the attaching surface  10   a  in the front-and-rear directions. Further, the height position of the pump main body  96   a  is between the supercharger  50  and the intercooler  60 . Additionally, the attachment position of the fuel pump  96  in the left-and-right directions is adjacent on the left side of the third passage  36  as indicated by a chain line in  FIG. 5 . 
       FIG. 15  is a view illustrating a positional relationship between the fuel pump  96  and the distribution passage  70 . The distribution passage  70  overlaps with the fuel pump  96 , particularly the pump main body  96   a  when the engine body  10  is seen from the upper side. For example, as indicated by a hatched portion in  FIG. 15 , the distribution passage  70  overlaps with a projected surface P of the pump main body  96   a  obtained by projecting the pump main body  96   a  onto a plane perpendicular to the up-and-down directions. 
     For example, when the engine body  10  is seen from the upper side, the rear side of the projected surface P overlaps with the distribution passage  70 , and the front side of the projected surface P slightly protrudes from an outer edge of the distribution passage  70 . A straight line L 1  which is in contact with a front edge of the projected surface P and extends in the left-and-right directions is located on the engine body side of a straight line L 2  which is in contact with a front edge of the distribution passage  70  and extends in the left-and-right directions. This means that although the pump main body  96   a  is not completely covered by the distribution passage  70 , the pump main body  96   a , including the uncovered portion, does not project forwardly (i.e., to the side opposite from the engine body  10 ) from the distribution passage  70 . 
     For example, when the vehicle on which the engine  1  having the above structure is mounted causes a front collision, the collision load is applied to the engine  1  from the front side. A portion of the load which is applied from the front side of the supercharger  50  acts on the supercharger  50  via the second passage  35 . Although the load moves the supercharger  50  rearwardly, i.e., to the engine body  10  side (e.g., the attaching surface  10   a  of the engine body  10 ) in relation to the vehicle, since the distribution passage  70  is provided between the supercharger  50  and the cylinder block  11 , the supercharger  50  comes into contact with the distribution passage  70 . Thus, the approach between the supercharger  50  and the engine body  10  is limited by the distribution passage  70 . 
     On the other hand, the distribution passage  70  overlaps with the pump main body  96   a  when the engine body  10  is seen from the upper side. Such an arrangement locates the pump main body  96   a  between the supercharger  50  and the engine body  10  when the engine  1  is seen from the upper side, similar to the distribution passage  70 . Therefore, the limitation of the approach between the supercharger  50  and the engine body  10  by the distribution passage  70  prevents the contact between the supercharger  50  and the pump main body  96   a , which leads to protecting the fuel pump  96  from the supercharger  50 . 
     Further, according to the above structure, the supercharger  50  and the fuel pump  96  may be brought close to each other in the up-and-down directions without separating them from each other, which is effective in reducing the size of the engine  1 . 
     Thus, according to the above structure, the fuel pump  96  is protected from the supercharger  50  while reducing the size of the engine  1 . 
     Further according to the above structure, by utilizing the distribution passage  70  which is a portion of the intake passage  30 , the fuel pump  96  is protected from the supercharger  50  without providing another member, which is effective in reducing the number of components of the engine  1 . 
     The fuel pump  96  of this embodiment is attached in a posture in which the pump main body  96   a  is arranged on the upper side and the cam accommodating part  96   c  is arranged on the lower side in the vertical directions. In such a posture, the tappet accommodating part  96   b  and the cam accommodating part  96   c  through which the fuel does not flow are downwardly spaced apart from the distribution passage  70 , and the pump main body  96   a  through which the fuel flows is located directly below the distribution passage  70 . Such an arrangement enables more reliable protection of the pump main body  96   a , which is a member preferentially be protected over the other members  96   b  and  96   c , by the distribution passage  70 . 
     The straight line L 1  contacting with the front edge of the projected surface P is located on the engine body side of the straight line L 2  contacting with the front edge of the distribution passage  70 . Thus, the pump main body  96   a  does not protrude forward (to the side opposite from the engine body  10 ) from the distribution passage  70 . As a result, the distribution passage  70  protects the pump main body  96   a  from the supercharger  50  without completely covering the pump main body  96   a . Further, when the supercharger  50  is in contact with the distribution passage  70 , the above structure is advantageous in reliably preventing the contact between the supercharger  50  and the pump main body  96   a.    
     The distribution passage  70  is attached to the engine body  10 . Disposing such a passage near the engine body  10  is advantageous in reducing the size of the engine  1 . 
     The second passage  35  is connected to the part of the supercharger  50  on the opposite side from the engine body  10 . Therefore, when the collision load is received from the opposite side of the engine body  10  (front side), the load is added to the supercharger  50  via the second passage  35 . Since the second passage  35  is a hollow member, it crushes according to the magnitude of the load. By crushing the second passage  35 , the impact applied to the supercharger  50  itself is subsided. Thus, the relative movement of the supercharger  50  is reduced, which becomes advantageous in reliably protecting the fuel pump  96 . 
     By fastening the supercharger  50  to the distribution passage  70 , the distribution passage  70  supports the supercharger  50 . Therefore, when the collision load is applied to the supercharger  50 , the approach between the supercharger  50  and the engine body  10  is limited more reliably by the distribution passage  70 , which is advantageous in reliably protecting the fuel pump  96 . 
     The supercharger  50  extends in the left-and-right directions along the attaching surface  10   a  of the engine body  10  and the left and right end sides of the supercharger  50  are fastened to the distribution passage  70  by the right and left end side brackets  52 R and  52 L, respectively. Thus, the supercharger  50  is stably supported. Therefore, the approach between the supercharger  50  and the engine body  10  is stably limited, which is advantageous in reliably protecting the fuel pump  96 . 
     In each of the right and left end side brackets  52 R and  52 L, the bolt is inserted in the up-and-down directions. Thus, for example, compared with a structure in which the bolt is inserted in the front-and-rear directions, a wide contact surface between the supercharger  50  and the distribution passage  70  is secured, which is advantageous in stably supporting the supercharger  50 . 
     Other Embodiments 
     The above embodiment may be modified as follows. 
     In the above embodiment, the engine  1  is the transverse four-cylinder engine; however, without limiting to this, the number of the cylinders may be three, five or more. Further, the engine  1  may be a vertical engine. In this case, the intake passage  30  and the fuel pump  96  are disposed on one of left and right side surfaces of the engine body  10 . 
     Further in the above embodiment, the supercharger  50  is the mechanically driven supercharger; however, without limiting to this, it may be an electric supercharger. 
     It should be understood that the embodiments herein are illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof, are therefore intended to be embraced by the claims. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
           1  Supercharged Engine 
           10  Engine Body 
           10   a  Attaching Surface (Intake-side Side Surface) 
           16  Intake Port 
           18  Cylinder 
           30  Intake Passage 
           35  Second Passage (Relay Part) 
           50  Supercharger 
           70  Distribution Passage (Intervening Part) 
           96  Fuel Pump