JP2008075606A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine in which the width of a whole air intake passage can be reduced in a crank shaft direction. <P>SOLUTION: Viewed from a combustion chamber 24d side of each cylinder, an upstream side part f1u of an axial line f1' of an intake port 24H is inclined so as to be positioned at an opposite side of a shaft end of a crankshaft 21 from a downstream side part f1d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine in which a crankshaft is disposed horizontally, and more particularly to an intake device for the engine.

For example, in an intake device for a parallel multiple cylinder engine mounted on a motorcycle, each intake passage is connected to the rear wall of the cylinder head so as to extend rearward, and the intake passages are arranged in parallel so as to be parallel to each other. A structure in which a fuel injection valve is disposed downstream of a throttle valve in each intake passage so as to face the back surface of the valve plate of the intake valve (for example, see Patent Document 1).
JP 2002-256895 A

  By the way, when the intake passages are arranged in parallel with each other as in the conventional intake device, the size of the entire intake passage tends to increase in the crankshaft direction, and the engine width increases accordingly. There is. For this reason, when this type of engine is mounted on, for example, a motorcycle, the rider's knee may interfere with the intake passage, which may cause a problem that it is difficult to ensure an optimal riding posture.

  Here, in order to make the engine width compact, it is conceivable that each intake passage is inclined such that the upstream portion is displaced inward in the crankshaft direction from the downstream portion. However, if the intake passage is inclined inward, the fuel injection direction of the fuel injection valve is deviated from the axis of the intake passage, and in some cases, the injected fuel may not hit the back surface of the valve plate of the intake valve. As a result, the valve seat that seals the intake valve is likely to wear. In particular, in the case of an air-cooled engine, the temperature of the valve seat part is likely to rise due to its structure, but when the fuel does not hit the back surface of the valve plate, it is difficult to lower the temperature of the valve seat part.

  The present invention has been made in view of the above-described conventional situation, and an object of the present invention is to provide an engine configured to reduce the width of the entire intake passage in the crankshaft direction.

  The present invention is an engine in which a crankshaft is disposed horizontally, and the engine opens and closes a combustion chamber formed in a cylinder, an intake port opening to the combustion chamber, and a combustion chamber opening of the intake port An intake valve and an intake passage connected to the intake port, and when viewed from the combustion chamber side of the cylinder, the upstream portion of the axis of the intake port is located on the opposite side of the shaft end of the crankshaft from the downstream portion. It is characterized by being inclined to be positioned.

  Here, in the present invention, the axis of the intake port is inclined. In the case where each intake port is composed of a branch port and a merge port where each branch port is merged, the centers of the branch axes of the branch ports are defined. It means that the merging axis that passes through forms an oblique axis.

  According to the engine of the present invention, the upstream portion of the intake port axis is inclined so as to be located on the opposite side of the crankshaft shaft end from the downstream portion, that is, on the engine center side. The crankshaft direction width of the connecting portion can be reduced, and the engine width can be reduced accordingly. Thus, for example, when mounted on a motorcycle, when the rider knee-grips, the rider's knee can be prevented from interfering with the intake passage, and the optimal riding posture can be easily secured.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 11 are diagrams for explaining an engine according to an embodiment of the present invention. Here, front and rear and left and right as used in the present embodiment mean front and rear and left and right when viewed in a seated state.

  In the figure, reference numeral 1 denotes a motorcycle. The motorcycle 1 includes a double cradle-type body frame 2, an engine 3 mounted in the cradle of the body frame 2, an intake device 4 and an exhaust device 5 connected to the engine 3, and the engine 3. And a fuel supply device 62 for supplying fuel.

  A front fork 7 is supported by a head pipe 6 disposed at the front end of the vehicle body frame 2 so as to be steerable left and right. A front wheel 8 is disposed at the lower end of the front fork 7, and a steering handle 9 is disposed at the upper end.

  A rear arm 10 is supported by a rear portion of the vehicle body frame 2 via a pivot shaft 12 so as to be able to swing up and down, and a rear wheel 11 is disposed at a rear end portion of the rear arm 10.

  A fuel tank 14 is disposed above the engine 3 of the body frame 2, and a straddle-type seat 15 is disposed on the rear side of the fuel tank 14.

  The vehicle body frame 2 includes tank rail portions 16a and 16a that extend slightly downward rearward from the top of the head pipe 6, and rear arm support portions 16b and 16b that extend rearward and obliquely downward from the rear end of the tank rail portion 16a. Left having a right upper tube 16, 16 and inclined portions 17a, 17a extending obliquely downward from the lower portion of the head pipe 6 and horizontal portions 17b, 17b extending substantially horizontally rearward from the lower end of the inclined portion 17a, Right down tubes 17 and 17 are provided.

  The vehicle body frame 2 includes left and right seat rails 18 and 18 that extend obliquely upward rearward from upper end portions of the left and right rear arm support portions 16b, a front-rear intermediate portion of the seat rail 18, and the rear arm support. Left and right seat stays 19 and 19 are provided to connect the lower portion of the portion 16b.

  The engine 3 is an air-cooled four-cycle parallel four-cylinder engine, which is mounted with the cylinder axis a tilted forward, and is suspended and supported by the left and right upper tubes 16 and the left and right down tubes 17. Yes.

  The engine 3 includes a cylinder block 23 and a cylinder head 24 in which cooling fins 23c and 24c are formed on the upper joint surface of a crankcase 22 in which a crankshaft 21 extending horizontally in the vehicle width direction is housed. A head cover 25 is attached to the cylinder head 24, and a transmission case 22a in which a transmission mechanism (not shown) is housed is integrally connected to the rear portion of the crankcase 22. The cylinder block 23 is formed with four cylinders 23 'arranged in parallel in the crankshaft direction. Although not shown, pistons arranged in the cylinders 23' are connected to the crankshaft 21 via connecting rods. It is connected.

  As shown in FIGS. 6 and 9, a combustion recess 24d constituting a combustion chamber is formed in a portion corresponding to each of the first to fourth cylinders 23 ′ of the lower joint surface 24a ′ of the cylinder head 24. Yes. Two intake valve openings 24e and 24e are formed for each cylinder on the rear side of each combustion recess 24d across the cylinder axis a, and two exhaust valve openings 24f and 24f are formed on the front side.

  In the intake valve openings 24e and the exhaust valve openings 24f, annular valve seats 31 and 32 for sealing between an intake valve 33 and an exhaust valve 34, which will be described later, are fitted.

  The exhaust valve openings 24f and 24f are joined to one exhaust joint port 24g 'by exhaust branch ports 24g and 24g, respectively, and led to the front wall 24a of the cylinder head 24.

  The intake valve openings 24e and 24e are led out to the rear wall 24b of the cylinder head 24 by an intake port 24H. The intake port 24H communicates with the intake valve opening 24e, and is connected to the outer branch port 24h 'located on the crankshaft shaft end side, that is, on the outer side in the engine width direction, and on the opposite side of the crankshaft shaft end, that is, in the engine width direction. It includes an inner branch port 24h ″ located on the center side and a merge port 24h where the outer and inner branch ports merge, and an external connection opening 24b ′ of the merge port 24h opens in the rear wall 24b.

  Here, the outer and inner branch ports 24h ′, 24h ″ and the merging port 24h are merging axes passing through the centers of branch axes f1o and f1i extending from the center a of the intake valve opening 24e to the center b of the external connection opening 24b ′. f1 'is formed to be inclined. That is, the merging axis f1 ′ is such that the upstream portion f1u corresponding to the merging port 24h is opposite to the crankshaft shaft end from the downstream portion f1d corresponding to the branch ports 24h ′ and 24h ″, that is, the engine. It inclines so that it may be located in the width direction center b side.

  In this case, an angle formed by a merging axis f1 ′ of the merging port 24h of the first and fourth cylinders located on the outer side in the vehicle width direction (crank shaft direction) with a straight line b ′ parallel to the engine center line b orthogonal to the crankshaft. θ1 ′ is set to an inclination angle larger than an angle θ2 ′ formed by a straight line b ″ parallel to the engine center line b of the merge axis f2 ′ of the merge port 24h of the second and third cylinders located on the inner side in the vehicle width direction. (See FIG. 9).

  Furthermore, the inclination angle θ1o of the branch axis f1o of the outer branch port 24h ′ of the first and fourth cylinders with respect to a straight line b ′ parallel to the engine center line b is the same as the axis f1i of the inner intake port 24h ″. The inclination angle θ1i with respect to the straight line b ′ is set larger. The same applies to the second and third cylinders. The inclination angle θ2o of the branch axis f2o of the outer branch port 24h ′ with respect to the straight line b ″ is equal to the straight line b ′ of the axis f2i of the inner intake port 24h ″. Is set larger than the inclination angle θ2i with respect to ′.

  In FIG. 9, C1 and C2 indicate the center line of the intake pipe connected to the external connection opening 24b ', and the inclination angles of the center lines C1 and C2 with respect to the straight lines b' and b "are as follows. θ1 and θ2 are smaller than the inclination angles θ1 ′ and θ2 ′.

  The cylinder head 24 is provided with the intake valve 33 and the exhaust valve 34 that open and close the intake openings 24e and the exhaust openings 24f. The intake valve 33 and the exhaust valve 34 are urged in the closing direction by valve springs 36 and 36, and are formed integrally with the valve plates 33a and 34a contacting the valve seats 31 and 32 and the valve plates 33a and 34a. Valve shaft 33b. 34b. Valve lifters 35 and 35 for slidably supporting the intake valve 33 and the exhaust valve 34 are mounted on the upper ends of the valve shafts 33b and 34b.

  The intake valve 33 and the exhaust valve 34 are driven to open and close by an intake cam shaft 37 and an exhaust cam shaft 38 disposed so as to press the valve lifter 35. The intake camshaft 37 and the exhaust camshaft 38 are arranged in parallel with the crankshaft 22 and are rotationally driven by the crankshaft 22 via a cam chain 39.

  The cam chain 39 is arranged between the second and third cylinders, specifically, so as to substantially coincide with the engine center line b that passes through the axial center of the crankshaft 22 and is orthogonal to the crankshaft 22. (See FIG. 9).

  The exhaust device 5 is connected to the front wall 24a of the cylinder head 24 so as to communicate with the exhaust ports 24g. The exhaust device 5 extends downward from the front wall 24a and then extends rearward through the lower side of the engine 3. An exhaust pipe 26, a left collective portion 27a where two exhaust pipes 26, 26 on the left in the vehicle width direction gather, a right collective portion 27b where two right exhaust pipes 26, 26 gather, and the left and right A main set unit 28 in which the set units 27a and 27b meet and a single muffler 29 connected to the main set unit 28 are provided (see FIG. 1).

  The intake device 4 is connected to the external connection opening 24b ′ of the rear wall 24b of the cylinder head 24 so as to communicate with the intake merging ports 24h. When viewed in the cam shaft direction, the intake device 4 is connected to the cylinder axis a from the rear wall 24b. First to fourth downstream intake pipes 40 to 43 that extend rearward so as to be substantially orthogonal to each other, and first to fourth upstream intake pipes 45 that are connected to extend rearward after the respective downstream intake pipes 40 to 43. ˜48 and a common air cleaner 49 connected to the first to fourth upstream side intake pipes 45 to 48 via a joint member 55.

  A butterfly main throttle valve 44a and a sub-throttle valve 44b are disposed in the first to fourth upstream intake pipes 45 to 48. The main throttle valves 44a and the sub throttle valves 44b are connected to each other by a common valve shaft 44c, 44d so as to be opened and closed.

  The first to fourth downstream sides 40 to 43 and the first to fourth upstream side intake pipes 45 to 48 form an intake passage, and the first to fourth downstream side and upstream side intake pipes 40 to 43, 45, 48 are arranged so as to have the same axis.

  The first to fourth downstream intake pipes 40 to 43 and the first to fourth upstream intake pipes 45 to 48 are connected by a rubber joint member 53, and a band member 54 attached to the joint member 53. It is fixed by.

  The first to fourth downstream side and upstream side intake pipes 40 to 43, 45 to 48 are arranged so as to be symmetrical on both sides of the engine center line b.

  The first and second downstream intake pipes 40 and 41, and the third and fourth downstream intake pipes 42 and 43 are formed integrally with a common attachment base 50 and 51, respectively. It is bolted and fixed to the rear wall 24b. Reference numeral 52 denotes a heat insulating plate, which is attached to the engine rear wall 24b together with the mounting bases 50 and 51.

  As shown in FIG. 7, the first to fourth downstream side intake pipes 40 to 43 and the first to fourth upstream side intake pipes 45 to 48 are each in the direction of the cylinder axis a, that is, when viewed from above. The upstream portions of the axes 40 to 43 and 45 to 48 are formed so as to form oblique axes C1 to C4 located on the inner side in the crankshaft direction than the downstream portion.

  In this case, the angles θ1 and θ4 of the first and fourth downstream intake pipes 40 and 43 located on the outer side in the vehicle width direction with respect to the engine center line b of the oblique axes C1 and C4 are the second and second angles located on the inner side thereof. It is set larger than the angles θ2 and θ3 of the oblique axes C2 and C3 of the third downstream side intake pipes 41 and 42. In other words, the outer intake pipes 40, 43 are more inclined than the inner intake pipes 41, 42, which contributes to narrowing the engine width.

  Specifically, the angles θ1 and θ4 of the oblique axes C1 and C4 of the first and fourth downstream intake pipes 40 and 43 with respect to the engine center line b are about 10 degrees. On the other hand, the angles θ2 and θ3 of the oblique axes C2 and C3 of the second and third downstream intake pipes 41 and 42 with respect to the engine center line b are about 5 degrees. The first to fourth upstream intake pipes 45 to 48 have the same inclination angles as the first to fourth downstream intake pipes 40 to 43.

  The inclination angles .theta.1 and .theta.2 of the intake pipe axes C1 and C2 are set to values smaller than the inclination angles .theta.1 'and .theta.2' of the merging axes f1 'and f2' of the intake side merging port 24h. Therefore, the intake pipes 40 and 41 are inclined more gently than the merging ports 247h and 24h.

  Boss portions 40a to 43a having valve holes 40b to 43b are bulged and formed on the upper wall portions of the first to fourth downstream side intake pipes 40 to 43 so as to extend along the axis lines C1 to C4.

  The first to fourth fuel injection valves 57 to 60 are mounted on the boss portions 40a to 43a. The first to fourth fuel injection valves 57 to 60, when viewed in the cylinder axial direction, are the joint members 53 disposed on the connecting surfaces of the downstream side intake pipes 40 to 43 and the upstream side intake pipes 45 to 48, respectively. The downstream intake pipes 40 to 43 are disposed so as to pass between the mounting bases 50 and 51.

  The first and fourth fuel injection valves 57 and 60 located on the outer side in the vehicle width direction are positioned on the axes C1 and C4 of the first and fourth downstream intake pipes 40 and 43 and the axes f1 ′ and f1 ′ of the intake merging port 24h. It is arranged so as to be substantially along and located on the inner side in the vehicle width direction with respect to the axes C1, C4, f1 ′, f1 ′.

  The second and third fuel injection valves 58 and 59 located on the inner side in the vehicle width direction are inclined axes C2 and C3 of the second and third downstream intake pipes 41 and 42 and an oblique axis f2 ′ of the intake merging port 24h. , F2 ′, and so as to be positioned on the outer side in the vehicle width direction with respect to the oblique axes C2, C3, f2 ′, f2 ′.

  The first and second fuel injection valves 57 and 58 and the third and fourth fuel injection valves 59 and 60 are arranged in directions with different axis angles. Specifically, when viewed from the plane, the first and fourth fuel injection valves 57 and 60 have the axes of the oblique axes C1 and C4 of the first and fourth downstream intake pipes 40 and 43 and the intake merging port. The second and third fuel injection valves 58 and 59 intersect the axes f1 ′ and f1 ′ from the inner side to the outer side in the vehicle width direction, and the axes of the second and third fuel injection valves 58 and 59 are the axes f2 ′ and f2 of the second and third intake merging ports. 'And parallel to the intake merging axes f2' and f2 'are arranged so as to intersect slightly from the outside in the vehicle width direction.

  Thus, the fuel injected from the fuel injection ports 57a to 60a of the first to fourth fuel injection valves 57 to 60 passes through the intake branch ports 24h and 24h, and the valve plates 33a of the left and right intake valves 33. It is jetted toward the back side. Here, in FIG. 9, a hatched portion A with mesh-like hatching shows a collision region of fuel injected into the intake port 24H, and after the fuel collides with this region, the valve of each intake valve It will move toward the plate part. Yes.

  The fuel supply device 62 is connected to the first to fourth fuel injection valves 57 to 60, and the fuel supply device 62 has the following structure.

  As shown in FIG. 7, the first to fourth fuel injection valves 57 to 60 include a first fuel injection valve 57 positioned on the left outer side in the vehicle width direction (crank shaft direction) and a second fuel positioned on the inner side thereof. A first valve group 65 having an injection valve 58, a fourth fuel injection valve 60 positioned on the right outer side in the vehicle width direction, and a second valve group 66 having a third fuel injection valve 59 positioned on the inner side thereof. It is divided.

  The first to fourth downstream intake pipes 40 to 43 have a first intake pipe having a first downstream intake pipe 40 positioned on the left outer side in the vehicle width direction and a second downstream intake pipe 41 positioned on the inner side thereof. The passage group 67 is divided into a second intake passage group 68 having a fourth downstream intake pipe 43 positioned on the right outer side in the vehicle width direction and a third downstream intake pipe 42 positioned on the inner side.

  The first valve group 65 is disposed in the first intake passage group 67, and the second valve group 66 is disposed in the second intake passage group 68. The first intake passage group 67 and the second intake passage group 68 are disposed so as to be symmetrical on both sides of the engine center line b (see FIG. 7).

  A first fuel supply rail 72 made of aluminum alloy casting is connected to the first and second fuel injection valves 57 and 58 of the first valve group 65, and the third and fourth of the second valve group 66 are connected. A second fuel supply rail 73 made of aluminum alloy casting is connected to the fuel injection valves 59 and 60.

  The first valve group 65, the first intake passage group 67, and the first fuel supply rail 72 are attached to the engine 3 as a preassembled assembly, and similarly, the second valve group 66, the second intake passage group. 68 and the first fuel supply rail 73 are attached to the engine 3 as an assembly assembled in advance. As described above, each part is divided into left and right assemblies, and each part is assembled in advance as one assembly, so that the assembly to the engine 3 can be improved and the assembly accuracy of each part is increased. be able to.

  The first and second fuel supply rails 72 and 73 are arranged in the vehicle width direction so that the respective axes e are inclined slightly rearward with respect to a straight line orthogonal to the engine center line b. It is attached to mounting bosses 50a and 51a formed so as to stand upright on the bases 50 and 51.

  The inclination angles of the first and second fuel supply rails 72 and 73 are set to correspond to different mounting angles of the first and second fuel injection valves 57 and 58 and the third and fourth fuel injection valves 59 and 60. Has been. Specifically, the first and second fuel supply rails 72 and 73 are disposed such that the outer side in the vehicle width direction is located behind the vehicle from the inner side and is at a low position.

  A fuel supply pipe 70 is connected to the outer end of the first fuel supply rail 72 in the vehicle width direction, and fuel in the fuel tank 14 is connected to the fuel supply pipe 70 via a fuel pump (not shown). A fuel supply hose 71 to be supplied is connected.

  A regulator 78 for adjusting the fuel pressure is connected to the axially inner end of the second fuel supply rail 73, and the regulator 78 is connected to the fuel tank 14 via a fuel return hose 79. Here, 80 is a boost hose, and 81 is a breather hose connected to a breather tank 82.

  The first fuel supply rail 72 and the second fuel supply rail 73 are connected by a connecting member 75. The connecting member 75 has one connecting hose 76 having flexibility, and left and right connecting members 77 and 77 that connect the connecting hose 67 and the first and second fuel supply rails 72 and 73. is doing.

  The left and right connecting members 77 include flange portions 77a detachably attached to boss portions 72a and 73a formed integrally with the first and second fuel supply rails 72 and 73 by bolts 83 and 83, respectively. It has a cylindrical part 77b connected to the flange part 77a and a joint part 77c formed to project from the cylindrical part 77b. The boss portions 72a and 73a are formed to extend in a direction orthogonal to the axis e of the first and second fuel supply rails 72 and 73.

  The left and right flange portions 77a are formed to extend in a direction perpendicular to the axis e of the fuel supply rails 72 and 73, similarly to the boss portions 72a and 73a. Further, the left and right joint portions 77c are formed so as to be obliquely upward and intersect the outer side in the crankshaft direction, that is, the outer side in the vehicle width direction so as to intersect the line connecting the bolts 83 of the flange portion 77a.

  The left and right joint portions 77c and the connection hose 76 are detachably connected via detachable connectors 85 and 85.

  As shown in FIG. 11, the left and right detachable connectors 85 include an insertion portion 85a inserted at both ends of the connection hose 76, and a housing portion 85b extending from the insertion portion 85a by bending in the direction perpendicular to the axis. And a clamp member 86 attached to the housing portion 85b.

  In the housing portion 85b, an engaging claw 85c with which a collar portion 77d formed in the joint portion 77c engages is cut out so as to be elastically deformable. The clamp member 86 is formed with a stopper portion 86a that can contact the outer peripheral surface of the joint portion 77c.

  The housing portion 85b is attached to the joint portion 77c from the rear (see FIG. 11A), and is pushed in until the flange portion 77d of the joint portion 77c engages with the engaging claw 85c (see FIG. 11B). Further, the clamp member 86 is pushed in until the stopper portion 86a comes into contact with the joint portion 77c (see FIGS. 11B and 11C). When removing, the clamp member 86 is elastically deformed outward and pulled up.

  According to the intake device 4 of the present embodiment, the upstream portion f1u of the axis f1 ′ of the intake port 24H is inclined so as to be positioned on the opposite side of the shaft end of the crankshaft from the downstream portion f1d, that is, on the engine centerline b side. As a result, the crankshaft direction width of the intake passage connection opening 24b 'of the intake port can be reduced, and the engine width can be reduced accordingly.

  In the present embodiment, the first to fourth downstream and upstream side intake pipes 40 to 43 and 45 to 48 connected to the rear wall 24b of the cylinder head 24 are connected to the upstream side of the intake pipes 40 to 43 and 45 to 48, respectively. Since the side portion is formed so as to form oblique axes C1 to C4 that deviate inward in the crankshaft direction from the downstream portion, the crankshafts of the first to fourth downstream side and upstream side intake pipes 40 to 43 and 45 to 48 are formed. The direction width can be reduced, and the vehicle width dimension of the entire engine 3 can be reduced accordingly. Accordingly, when the rider seated on the seat 15 knee-grips, the rider's knee (see the two-dot chain line in FIG. 7) can be prevented from interfering with the intake passage, and the riding posture can be stabilized.

  Furthermore, the inclination angle θ1o with respect to the engine center line b of the outer intake port 24h ′ located on the shaft end side of the crankshaft, that is, on the outer side in the engine width direction is set to the opposite side of the crankshaft shaft end, that is, the engine width direction center side. Since the inner intake port 24h ″ positioned at a position is set to be larger than the inclination angle θ1i with respect to the engine center line b, even when the branch port is provided, the entire intake port 24H can be inclined so that the upstream side is positioned inside. Reduction of the engine width dimension described above can be realized.

  In the present embodiment, the first to fourth fuel injection valves 57 to 60 are connected to the oblique axes C1 to C4 of the first to fourth downstream intake pipes 40 to 43 and the axis f1 ′ of the intake merging port of the intake merging port. Since it is arranged so as to be directed along the direction f2 ′ and toward the back surface of the valve plate 33a of each intake valve 33, the fuel is supplied to the intake valve 33 while the intake pipes 40 to 43 and the merging port 27h ′ are inclined inward. Can be supplied by spraying so as to hit the back surface of the valve plate. Thereby, the cooling performance of the valve seat 31 that seals the intake valve 33 can be ensured, and wear of the valve seat 31 can be suppressed.

  In particular, in the case of the air-cooled engine 3, the temperature of the valve seat 31 may not be sufficiently lowered depending on the arrangement position of the fuel injection valves 57 to 60 due to its structure. In this embodiment, since it was set as the said structure, the temperature of the valve seat 31 part can be lowered | hung with the fuel injected and supplied from each fuel injection valve 57-60, and abrasion of this valve seat 31 can be suppressed.

  In the present embodiment, the angles θ1 and θ4 of the oblique axes C1 and C4 of the first and fourth downstream intake pipes 40 and 43 and the upstream intake pipes 45 and 48 located on the outer side in the crankshaft direction are set on the inner sides. Since the angles θ2 and θ3 of the second and third intake pipes 41, 42 and 46, 47 are set larger, the engine width can be made smaller.

  In the present embodiment, since the first to fourth fuel injection valves 57 to 60 are arranged in the first to fourth downstream intake pipes 40 to 43, the upstream intake pipes 45 to 48 incorporating the throttle valves 44a and 44b. The fuel injection valves 57 to 60 can be easily attached and detached and the boss portions 40a3 and 43a can be easily formed as compared with the case where the fuel injection valves 57 and 60 are disposed.

  In the present embodiment, the first and second downstream and upstream intake pipes 40, 41, 45 and 46 and the third and fourth downstream and upstream intake pipes 42, 43, 47 and 48 are connected to the engine center line. Since it arrange | positions so that it may become left-right symmetrical on both sides on both sides of b, while being able to improve the assembly property to the engine 3, the assembly accuracy of each component can be improved.

  In the present embodiment, the cam chain 39 that drives the intake and exhaust camshafts 37 and 38 is disposed between the second and third downstream intake pipes 41 and 43. Therefore, the cam chain 39 is disposed on the engine center line b. In this case, the engine width can be suppressed from increasing. That is, when the cam chain 39 is arranged at the center of the engine, it is necessary to widen the distance between the second and third downstream intake pipes 41 and 42. In this embodiment, the intake pipes 40 to 43 are inclined diagonally inward. Since it formed so that C1-C4 might be made, the vehicle width dimension of the whole intake passage does not become so large.

  In the above embodiment, a four-cylinder engine has been described as an example. However, the intake device of the present invention can be applied to a two-cylinder engine or a six-cylinder engine.

1 is a side view of a motorcycle including an engine intake device according to an embodiment of the present invention. It is a top view of the said intake device. It is a left view of the said intake device. It is a right view of the said intake device. It is a rear view of the intake device. FIG. 5 is a cross-sectional side view of the intake device (a cross-sectional view taken along line VI-VI in FIG. 2). It is a top view of the 1st-4th downstream intake pipe of the above-mentioned intake device. It is a rear view of the said 1st-4th downstream intake pipe. It is a bottom view of the cylinder head of the engine. It is sectional drawing of the fuel supply rail of the said engine. It is an assembly drawing of the detachable connector of the fuel supply rail.

Explanation of symbols

1 Motorcycle.

3 Engine 21 Crankshaft 23 'Cylinder 24d Combustion recess (combustion chamber)
24e Inlet valve opening (combustion chamber opening)
24H Intake port 24h Merge port 24h ′ Outer intake branch port 24h ″ Inner intake branch port 33 Intake valve 37 Intake cam shaft 39 Cam chains 40 to 43 Downstream intake pipe (intake passage)
44a, 44b Throttle valves 45 to 48 Upstream intake pipe (intake passage)
57-60 Fuel injection valve a Cylinder axis b Engine center line f1 ', f2' Intake port axis f1i, f2i Inner intake branch port axis f1o, f2o Outer intake branch port axis f1u, f2u Upstream part f1d, f2d Downstream Side portion θ1o, θ2o Outside intake port inclination angle θ1i, θ2i Inner intake port inclination angle

Claims (10)

An engine with a horizontally arranged crankshaft,
The engine includes a combustion chamber formed in a cylinder, an intake port that opens to the combustion chamber, an intake valve that opens and closes the combustion chamber opening of the intake port, and an intake passage connected to the intake port,
An engine characterized in that when viewed from the combustion chamber side of the cylinder, the upstream portion of the intake port axis is inclined to be located on the opposite side of the crankshaft shaft end from the downstream portion. 2. The intake port according to claim 1, wherein a plurality of intake valves are provided for each cylinder, and the intake port includes a branch port communicating with each intake valve opening and a merging port with which each branch port merges. The upstream portion of the engine is the axis of the merging port, and the downstream portion of the intake port is the axis of the branch port. 2. The crankshaft according to claim 1, further comprising a plurality of cylinders arranged side by side in the direction in which the crankshaft extends, wherein at least an upstream portion of an axis of an intake port of a cylinder on a shaft end side of the crankshaft is more An engine which is inclined so as to be located on the opposite side of the engine. 2. The fuel injection valve according to claim 1, further comprising a fuel injection valve mounted in the intake passage, wherein the fuel injection valve faces the intake valve when the fuel is viewed in a direction substantially along the axis of the intake port and in the cylinder axial direction. An engine that is arranged to inject in a direction. 2. The intake port according to claim 1, wherein the intake port includes an outer intake port located on an axial end side of the crankshaft and an inner intake port located on an opposite side of the crankshaft axial end. An engine is characterized in that an inclination angle with respect to an engine center line orthogonal to the crankshaft is set to be larger than an inclination angle of an axis line of the inner intake port with respect to the engine center line. 2. The intake passage according to claim 1, wherein the intake passage includes a downstream side intake pipe connected to the intake port, and an upstream side intake pipe connected to the downstream side intake pipe and having a built-in throttle valve. An engine mounted on the downstream side intake pipe. 2. The engine according to claim 1, wherein each of the intake ports is arranged so as to be symmetrical with respect to both sides of the engine center line. The camshaft for opening and closing the intake valve and a cam chain for driving the camshaft, wherein the cam chain is disposed between intake ports disposed on both sides of the engine center line. An engine characterized by 3. The engine according to claim 2, wherein the engine is air-cooled. A combustion chamber formed in the cylinder; an intake port that opens to the combustion chamber; an intake valve that opens and closes the combustion chamber opening of the intake port; and an intake passage that is connected to the intake port. When viewed from the room side, an engine that is inclined so that the upstream portion of the axis of the intake port is positioned on the opposite side of the shaft end of the crankshaft from the downstream portion is mounted on the vehicle body so that the crankshaft is horizontal. Motorcycle characterized by that.

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