Patent Publication Number: US-6659058-B2

Title: Intake system of a V-type engine

Description:
FIELD OF THE INVENTION 
     This invention relates to an intake system of a V-type combustion engine, and more particularly to an intake system of a V-type engine having a surge tank above and between engine banks of the V-type engine. 
     BACKGROUND OF THE INVENTION 
     An engine may comprise cylinders disposed in a straight line, opposed cylinders, or cylinders in a V-shaped form. 
     An intake system of the type for a V-type engine comprises, as shown in FIG. 8, first and second surge tanks  108 A,  108 B, first and second intake pipes  114 A,  114 B, and first and second fuel delivery pipes  118 A,  118 B. The surge tanks  108  are separated from one another, and are disposed above a space  106  defined between a first engine bank  104 A (a right bank) and a second engine bank  104 B (a left bank) of the V-type engine  102 . The intake pipes  114 A,  114 B branch and extend from sides of the surge tanks  108 A,  108 B and intersect (i.e., cross) below the surge tanks  108 , and then connect to first and second cylinder heads  110 A,  110 B of the engine banks  104 A,  104 B respectively. The fuel delivery pipes  118 A,  118 B are positioned in first and second spaces  116 A,  116 B below the surge tanks  108 A,  108 B and above the intake pipes  114 A,  114 B. 
     Also, another intake system of a V-type engine is divided into upper and lower block members, wherein the upper block includes a surge tank and first and second upper pipe parts of intake pipes, and the lower block includes first and second lower pipe parts of the intake pipes. 
     Further, such an intake system of the V-type engine is disclosed in e.g. Japanese Patent Laid-Open Official Gazette No. 62-237028, Japanese Patent Laid-Open Official Gazette No. 11-294171, and Japanese Patent Laid-Open Official Gazette No. 59-565. 
     The intake system disclosed in Japanese Patent Laid-Open Official Gazette No. 62-237028 has a constitution in which intake passages are connected to intake ports on the inward sides of banks of cylinder heads, and are positioned in recesses, which is formed in cylinder head covers, correspondingly to cylinder head bearings of camshafts in the other bank. Also, the intake system disclosed in Japanese Patent Laid-Open Official Gazette No. 11-294171 has volume chambers and resonance passage parts formed integrally in a collector. Further, the intake system disclosed in Japanese Patent Laid-Open Official Gazette No. 59-565 includes a supercharge high pressure pipe type intake manifold which is arranged in a relatively wide space between cylinders of the V-type engine. A space for adjacent outer engine elements is secured to permit smaller composition. 
     However, the conventional intake system of the V-type engine has inconvenience when the intake system is divided into an upper block which includes the surge tank and the upper pipe parts of the intake pipes, and a lower block, which includes the lower pipe parts of the intake pipes. That is, seal parts of the intake pipes enter inwardly into the surge tank, and therefore coupling bolts for coupling the upper and lower blocks are also required on the inner side of the surge tank to provide sealability of the intake pipes. This requirement results in complicated constitution of the system, difficulty of assembly of delivery pipes, and a heavier system. 
     In order to obviate the above inconveniences, the present invention provides an intake system of a V-type engine having a surge tank above and between first and second engine banks of the V-type engine. First and second intake pipes form therein first and second intake passages, and branch and extend from both sides of the surge tank to cross below the surge tank to connect to the engine banks. In first and second spaces which are defined by a lower part of the surge tank and upper parts of the intake pipes, first and second delivery pipes are disposed. An intake system structure is formed by the surge tank and the intake pipes. The intake system structure is divided into upper and lower blocks by a horizontal dividing surface positioned below the surge tank. The upper block includes the surge tank, and first and second upper pipe parts of the intake pipes. The lower block includes first and second lower pipe parts of the intake pipes. First and second seal parts surround the intake passages on the dividing surface toward the upper block. First and second straight inner sealing surfaces are arranged at the portion where the seal parts extend internally toward the engine banks. Only these straight inner sealing surfaces are positioned below the surge tank. 
     According to the present invention, the intake system structure is thus divided into upper and lower blocks, so that installation of fuel delivery pipes below the surge tank can be made easier. Also, the inner seal parts of the intake pipes are formed to be straight, and only these parts are positioned below the surge tank, so that the seal parts on the dividing surface of the intake pipes do not protrude inwardly toward the surge tank. Accordingly, the sealability of the intake pipes can be achieved without coupling bolts on the inner side of the surge tank, which permits easier composition and a lighter system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of an intake system structure according to a first embodiment and taken along line I—I in FIG.  2 . 
     FIG. 2 is a front view of the intake system structure. 
     FIG. 3 is an enlarged view of a main part of the intake structure shown in FIG.  2 . 
     FIG. 4 is a cross-sectional view showing a seal part of the intake system structure. 
     FIG. 5 is a cross-sectional view showing a V-type engine according to the first embodiment. 
     FIG. 6 is a cross-sectional view showing upper and lower connecting flanges according to a second embodiment. 
     FIG. 7 is a cross-sectional view of the intake system structure according to a third embodiment. 
     FIG. 8 is a cross-sectional view of a conventional V-type engine. 
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described in specific detail with reference to FIGS. 1 to  5  which illustrate a first embodiment of this invention. 
     FIG. 5 shows a multi-cylinder V-type engine  2 . This V-type engine  2  has first and second cylinder heads  8 A,  8 B on V-shaped first and second cylinder banks  6 A,  6 B as defined on the upper part of cylinder block  4 . First and second cylinder head covers  10 A,  10 B are mounted on the cylinder heads  8 A,  8 B. A bearing cap  12  is attached at its top to the lower part of the cylinder block  4  and at its bottom to an oil pan  14 . 
     In this V-type engine  2 , a first engine bank (a left bank)  16 A is defined by the first cylinder bank  6 A, the first cylinder head  8 A, and the first cylinder head cover  10 A. A second engine bank (a right bank)  16 B is defined by the second cylinder bank  6 B, the second cylinder head  8 B, and the second cylinder head cover  10 B. A V-shaped space  18  is defined between the engine banks  16 A,  16 B. 
     A horizontal upper wall  20  of the cylinder block is formed between the cylinder banks  8 A,  8 B and is provided with a cooling water discharge pipe  22  extending from above in the space  18  toward a crankshaft  24 . 
     The rotatably supported crankshaft  24  is disposed between the cylinder blocks  4  and the bearing cap  12 . 
     Each first cylinder  26 A is formed in the cylinder bank  6 A and has a first slidable piston  28 A which is connected to a smaller end of a first connecting rod  30 A. The connecting rod  30 A has a larger end connected to the crankshaft  24 . Similarly, each second cylinder  26 B is formed in the cylinder bank  6 B and has a second slidable piston  28 B which is connected to a smaller end of a second connecting rod  30 B. The connecting rod  30 B has a larger end connected to the crankshaft  24 . 
     A first inner intake camshaft  32 A-I and a first outer exhaust camshaft  32 A-E are rotatably supported in the upper part of the cylinder head  8 A. A first combustion chamber  34 A is formed in the lower part of the cylinder head  8 A. A first inner intake port  36 A-I, and a first outer exhaust port  36 A-E are formed to connect to the combustion chamber  34 A. First intake and exhaust valves  38 A-I,  38 A-E correspond to the intake and exhaust ports  36 A-I,  36 A-E. Similarly, second inner and outer intake camshafts  32 B-I,  32 B-E are rotatably supported in the upper part of the cylinder head  8 B. A second combustion chamber  34 B is formed in the lower part of the cylinder head  8 B. A second inner intake port  36 B-I and a second outer exhaust port  36 B-E are formed to connect to the combustion chamber  34 B. Second intake and exhaust valves  38 B-I,  38 B-E correspond to the intake and exhaust ports  36 A-I,  36 A-E. 
     A first intake port forming wall  40 A-I toward the bank space  18 , which forms the first intake port  36 A-I, includes upper surface  42 A-I of the first intake port as a horizontal plane. Similarly a second intake port forming wall  40 B-I toward the bank space  18 , which forms the second intake port  36 B-I, includes upper surface  42 B-I of the second intake port as a horizontal plane. 
     Also, in the V-type engine  2 , an intake system structure  44  is disposed above the space  18  between the engine banks  16 A,  16 B. 
     This intake system structure  44  can be formed from material of, e.g., metal, casting, and resin. The structure  44  integrally comprises first and second intake pipes  48 A,  48 B which form therein first and second intake passages  46 A,  46 B, and a surge tank  50 . The surge tank  50  is defined by upper and lower tank walls  50 - 1 ,  50 - 2 , end tank walls  50 - 3 , and side tank walls  50 - 5 ,  50 - 6 , thereby forming a certain volume. 
     The first intake pipe  48 A comprises a first upper pipe part  48 A-U and a first bent lower pipe part  48 A-L. The upper pipe part  48 A-U includes a first intake port  52 A inserted into the surge tank  50  from one side tank wall  50 - 5 . Also, the second intake pipe  48 A comprises first upper and lower pipe parts  48 B-U,  48 B-L. The upper pipe part  48 B-U includes a second intake port  52 B which is inserted into the surge tank  50  from the other side tank wall  50 - 6  The lower pipe parts  48 A-L,  48 B-L of the intake pipes  48 A,  48 B branch and extend from both sides of the surge tank to intersect (i.e., cross) below the surge tank  50  to connect to the upper surfaces  42 A-I,  42 B-I of the cylinder heads  8 A,  8 B in the engine banks  16 A,  16 B. 
     The intake system structure  44  is divided into upper and lower blocks  54 U,  54 L by a horizontal dividing surface “P” below the surge tank  50 . The surface “P” is generally at the level of the bottom wall  50 - 2  of the surge tank in the preferred embodiment. The upper block (an upper intake manifold)  54 U is integrally formed of the surge tank  50  and upper intake pipe parts  48 A-U,  48 B-U. The lower block (a lower intake manifold)  54 L is formed of lower pipe parts  48 A-L,  48 B-L. 
     A first upper connecting flange  56 A-U is formed on the side of the upper pipe part  48 A-U in the upper block  54 U toward the dividing surface “P”. The upper connecting flange  56 A-U has therein a pair of first upper block coupling holes  58 A-U,  58 A-U along the tank wall  50 - 5 . Similarly, a second upper connecting flange  56 B-U is formed on the side of the upper pipe part  48 B-U in the upper block  54 U toward the dividing surface “P”. The upper connecting flange  56 B-U has therein a pair of first upper block coupling holes  58 B-U,  58 B-U along the tank wall  50 - 6 . Coupling bolts (not shown) are inserted into the coupling holes  58 A-U,  58 A-U,  58 B-U,  58 B-U. 
     In addition, a first lower connecting flange  56 A-L corresponding to the upper connecting flange  56 A-U is formed on the lower pipe parts  48 A-L of the lower block  54 L. A second lower connecting flange  56 B-L is formed on the lower pipe part  48 B-L of the lower block  54 L. 
     First and second seal parts  60 A,  60 B surrounding the intake passages  46 A,  46 B are formed on the side of the upper connecting flange  56 A-U,  56 B of the upper block  54 U toward the dividing surface “P”. A groove  62 A for sealing is formed in the seal part  60 A as show in FIGS. 2 and 3, and an O-ring  64 A as a sealing material is disposed therein. Similarly, an O-ring (not shown) is disposed in the seal part  60 B. 
     First and second straight inner seal surfaces  66 A,  66 B of the seal parts  60 A,  60 B are formed at a position where the seal parts extend inwardly of the respective engine banks  16 A,  16 B. 
     The straight inner seal surfaces  66 A,  66 B are arranged such that only these surfaces are disposed below the surge tank  50  and inserted thereinto. The surfaces  66 A,  66 B are aligned to extend generally along the side walls  50 - 5 ,  50 - 6  of the surge tank  50 . 
     In the upper block  54 U, first and second planar walls  68 A,  68 B at the back of the straight inner seal surfaces  66 A,  66 B connect the space between adjacent inner seal surfaces  66 A,  66 B with the surge tank  50 . The walls  68 A,  68 B are formed to be generally in line with the inner seal surfaces  66 A,  66 B. 
     These planar walls  68 A,  68 B define a part of the side tank walls  50 - 5 ,  50 - 6  as an inner space forming wall of the surge tank  50 . 
     First and second delivery pipes  72 A,  72 B are disposed in spaces  70 A,  70 B which are defined by the lower part of the surge tank  50  and the lower part of the intake pipes  48 A,  48 B. The delivery pipes  72 A,  72 B are connected to first and second fuel injection valves  74 A,  74 B which are fixed to the lower pipe parts  48 A-L,  48 B-L. 
     The operation of the above embodiment will now be briefly described. 
     The seal parts  60 A,  60 B which surround the intake passages  46 A,  46 B are disposed on the upper connecting flanges  56 A-U,  56 B-U on the side toward the dividing surface “P”. The straight inner seal surfaces  66 A,  66 B of the seal parts  60 A,  60 B are formed at a position where the seal parts extend inwardly of the engine banks  16 A,  16 B. Further, only these inner seal surfaces  66   a,    66 B are projected inwardly so as to be positioned below the surge tank  50 . 
     The intake system structure  44  is divided into the upper and lower blocks  54 U,  54 L at the lower surface of the surge tank  50 , so that the upper block  54 U can be removed from the lower block  54 L in case of installation of the delivery pipes  72 A,  72 B. Accordingly, the delivery pipes  72 A,  72 B below the surge tank  50  can be easily mounted to improve installation. In addition, the seal parts toward the inner side of the intake pipes  48 A,  48 B are formed to be straight, and only these parts project inwardly below the surge tank  50 . Accordingly, the sealability of the intake pipes  48 A,  48 B can be attained without the coupling bolts going into the interior of the surge tank  50 , so that the construction can be made simpler and of reduced weight. 
     Also, in the upper block  54 U, the planar walls  68 A,  68 B are disposed at the back of the straight inner seal surfaces  66 A,  66 B, and these walls communicate with adjacent inner seal surfaces  66 A,  66 B which are part of the surge tank  50 . The planar walls  68 A,  68 B are formed in line with the inner seal surfaces  66 A,  66 B. Accordingly, the connection between the adjacent inner seal surfaces  66 A and between the adjacent inner seal surfaces  66 B can be improved. This prevents the seal surfaces inside of the surge tank  50  from deforming so as to improve the sealability. 
     Further, the planar walls  68 A,  68 B are a part of the space forming walls of the surge tank  50 . Accordingly, the strengthening planar walls  68 A,  68 B between the seal parts  60 A,  60 B and the walls forming the inner space of the surge tank  50  can be shared, so that the intake system structure  44  can be made compactly and of reduced weight. 
     FIG. 6 shows a specific constitution of the present invention as a second embodiment of the invention. In this second embodiment, the same functional parts are designated by the same reference numerals with respect to the first embodiment. 
     The second embodiment is characterized in that upper and lower block coupling holes  58 -U,  58 -L are formed in the upper and lower connecting flanges  56 -U,  56 -L respectively. Also, for example, on the seal surface of the lower connecting flange  56 -L, a first inclined surface  82  is formed at an angle θ 1  in the vicinity of the lower block coupling hole  58 -L. A second inclined surface  84  is formed at an angle θ 2  smaller than θ 1  away from the lower coupling hole  58 -L toward the inner seal surface  66 . The upper and lower connecting flanges  56 -U,  56 -L are secured by threading the coupling bolt  86  into the upper and lower holes  58 -U,  58 -L and screwing a coupling nut  88  onto the bolt  86 . 
     According to the second embodiment, clamping of the upper and lower connecting flanges  56 -U,  56 -L by the bolt  86  and nut  88  causes the lower flange  56 -L to bend in the vicinity of the lower hole  58 -L. The lower flange  56 -L can be strongly joined to the upper flange  56 -U at the portion of the inner seal surface  66  away from the lower holes  58 -L, so that the sealability of the upper and lower flanges  56 -U,  56 -L can be improved by this simple constitution. 
     FIG. 7 shows a specific constitution of the present invention as a third embodiment of the invention. 
     The third embodiment is characterized in that first and second block coupling holes  58 - 1 ,  58 - 2  are formed in the connecting flange  56 , and are arranged to be on the line “Z” which intersects the inner seal surface  66 . The block coupling hole  58 - 1  is placed, e.g., inside the tank wall  50 - 5  of the surge tank  50 , and the block coupling hole  58 - 2  is placed outside the tank wall  50 - 5 . 
     According to the third embodiment, coupling of the upper and lower blocks  54 U,  54 L improves the sealability of the inner seal surface  66 , since the diagonal sealing force between inner and outer surfaces of tank wall  50 - 5  is applied to the inner seal surface  66 . 
     As is clear from the above detailed description, according to the present invention, in a V-type engine, an intake system structure is formed of the surge tank and the intake pipes. The intake system structure is divided into upper and lower blocks by a horizontal dividing surface positioned below the surge tank. The upper block includes the surge tank, and first and second upper pipe parts of the intake pipes. The lower block includes first and second lower pipe parts of the intake pipes. First and second seal parts surround the intake passages on the dividing surface toward the upper block. First and second straight inner sealing surfaces are arranged at the portion where the seal parts extend internally of the engine banks. Only these straight inner sealing surfaces are positioned below the surge tank. Accordingly, the intake system structure is divided into upper and lower blocks so that installation of fuel delivery pipes below the surge tank can be made easier. Also, the inner seal parts of the intake pipes are formed to be straight, and only these parts are positioned below the surge tank, so that the seal parts on the dividing surface of the intake pipes do not protrude inwardly toward the surge tank. Accordingly, the sealability of the intake pipes can be achieved without the coupling bolts on the inner side of the surge tank, which permits easier composition and a lighter system. 
     Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.