JP7087510B2 - Engine intake passage structure - Google Patents

Description

The present invention relates to an engine intake passage structure.

An engine intake device including a main port, an intake port divided into three on the left and right sides of the main port, and an injector for injecting fuel into the main port is known (for example, Patent Document 1). reference).

Jitsukaihei 7-38665 Gazette

In general, the flow of intake air drawn into the combustion chamber of an engine diverts to curve at the intake port of the cylinder head.

The intake system of a conventional engine branches into a subport and discharges a part of the intake air to the left and right sides of the outlet of the main port. Therefore, the intake device of the conventional engine prevents the fuel injected from the injector from adhering to the left and right sides of the outlet of the main port and the inner wall surface on the downstream side of the sub port.

However, it is difficult for the intake device of a conventional engine to prevent fuel from adhering to the upper and lower inner wall surfaces of the outlet of the main port, particularly to the upper inner wall surface corresponding to the outer peripheral side of the intake air that curves and flows in the intake port. .. The upper inner wall surface corresponding to the outer peripheral side of the intake air curved in the intake port corresponds to directly behind the outlet of the injector that injects fuel into the intake passage (downstream directly below) following the direction of the intake air flow. ..

When the fuel adheres to the inner wall surface of the intake passage, the air-fuel ratio of the air-fuel mixture becomes thinner (lean) by the amount of the fuel adhering to the inner wall surface of the intake passage.

Therefore, an object of the present invention is to provide an engine intake passage structure that more reliably suppresses the adhesion of fuel to the inner wall surface of the intake passage and stabilizes the air-fuel ratio of the air-fuel mixture.

In order to solve the above problems, the engine intake passage structure according to the present invention is an engine intake passage structure including an intake passage for guiding intake to the combustion chamber of the engine, and the intake passage is a downstream end of the throttle body. An intake manifold connected to the intake manifold and curved in an arc shape, a fuel injection device having a fuel injection port for injecting fuel into the intake and provided in the intake manifold, and a fuel injection device arranged on the upstream side of the fuel injection port. The intake manifold is provided with a branch passage inlet and a branch passage outlet arranged on the downstream side of the fuel injection port and attached to the fuel injection port, and a part of the intake air in the intake manifold is circulated. The intake manifold is connected to the throttle body and has a linear shape. An upstream straight portion extending in a straight line, a downstream straight portion connected to the intake port of the engine and extending linearly, and a curved portion provided between the upstream straight portion and the downstream straight portion and curved in an arc shape. The downstream straight portion is outside the downstream projection of the upstream straight portion, and the upstream straight portion is the upstream projection of the downstream straight portion. The fuel injection device is provided on the outside, the downstream side straight portion near the outside of the curved portion of the intake manifold, or the outside of the curved portion of the intake manifold, and the recessed portion is the fuel. It has a bottom surface portion on which the injection port and the branch passage outlet are arranged, and a side surface portion including a portion arranged on the downstream side of the branch passage outlet, and the branch passage inlet and the branch passage outlet are described. The branch passage outlet opens in the tangential direction of the curved portion of the intake manifold, is farther from the center of the passage in the intake manifold than the fuel injection port, and the side surface portion of the fuel injection port and the recessed portion. The branch passage portion is arranged between the above and the upstream side straight passage that extends linearly from the branch passage entrance and the downstream side straight passage that is connected to the upstream side straight passage and extends linearly toward the branch passage exit. And have .

According to the present invention, it is possible to provide an engine intake passage structure that more reliably suppresses the adhesion of fuel to the inner wall surface of the intake passage and stabilizes the air-fuel ratio of the air-fuel mixture.

The left side view which shows an example of the motorcycle to which the intake passage structure which concerns on embodiment of this invention is applied. Sectional drawing of the intake passage structure of the engine which concerns on embodiment of this invention. Sectional drawing of the intake passage structure of the engine which concerns on embodiment of this invention. Sectional drawing of the intake passage structure of the engine which concerns on embodiment of this invention. The view which looked at the intake manifold of the intake passage structure which concerns on embodiment of this invention from the opening on the upstream side. The perspective sectional view passing through the center line of the straight passage on the downstream side of the branch passage part of the intake passage structure which concerns on embodiment of this invention. The figure which looked at the intake manifold of the branch passage part of the intake passage structure which concerns on embodiment of this invention from the outside of a curved part. The figure which looked at the intake manifold of the branch passage part of the intake passage structure which concerns on embodiment of this invention from the normal direction of the virtual plane passing through the mainstream passage. The cross-sectional view which passes through the center line of the straight passage on the upstream side of the branch passage part of the intake passage structure which concerns on embodiment of this invention.

An embodiment of the intake passage structure of the engine according to the present invention will be described with reference to FIGS. 1 to 9.

FIG. 1 is a left side view showing an example of a motorcycle to which the intake passage structure according to the embodiment of the present invention is applied.

In the present embodiment, the front-rear, up-down, and left-right expressions are based on the passenger of the motorcycle 1.

As shown in FIG. 1, the motorcycle 1 according to the present embodiment is a scooter type vehicle.

The motorcycle 1 includes a body frame 3 extending in the front-rear direction of the motorcycle 1, a power unit 5 supported by the body frame 3 and swingable in the vertical direction of the motorcycle 1, and a motorcycle 1 supported by the body frame 3. A steering mechanism 6 that can be steered in the left-right direction, a rotatable front wheel 7 that is supported by the steering mechanism 6, a rotatable rear wheel 8 that is supported by the power unit 5, and a vehicle body cover 9 that covers the vehicle body frame 3. I have.

The steering mechanism 6 includes a pair of left and right front forks 11 that sandwich and rotatably support the front wheels 7, a suspension mechanism (not shown) built in the left and right front forks 11, and a front fender 12 that covers above the front wheels 7. And a handlebar 13 provided on the top of the front fork 11.

The front wheels 7 are rotatably supported by front wheel axles (not shown) that span the lower ends of the left and right front forks 11.

The handlebar 13 is provided with grips 15 at the left and right ends. The grip 15 on the right side of the vehicle serves the throttle function of the engine 17. Further, a brake lever (not shown) is provided in front of each of the left and right grips 15. The brake lever on the right side is connected to the brake of the front wheel 7 (not shown). The brake lever on the left side is connected to the brake of the rear wheel 8 (not shown).

The power unit 5 is swingably supported by the lower end portion of the vehicle body frame 3 via the link mechanism 18. The power unit 5 integrally includes an engine 17 and a power transmission device 23. The power unit 5 is a unit swing type that integrally swings the engine 17, the power transmission device 23, and the rear wheel 8.

Further, the power unit 5 is elastically supported by the vehicle body frame 3 via the rear cushion unit 27. The rear cushion unit 27 cushions the force transmitted from the rear wheel 8 to the vehicle body frame 3.

The engine 17 generates a driving force for the rear wheels 8. The engine 17 generates electric power consumed by each part of the motorcycle 1. The power transmission device 23 shifts the output of the engine 17 and transmits it to the rear wheels 8 as drive wheels.

The engine 17 lays the cylinder 31 toward the front of the motorcycle 1. In other words, the center line of the cylinder bore 31a of the engine 17 faces the front-rear direction of the motorcycle 1. That is, the engine 17 includes a cylinder 31 provided on the front side of the crankcase 32, a cylinder head 33 provided on the front side of the cylinder 31, and a head cover 35 provided on the front side of the cylinder head 33.

The engine 17 may have the cylinder 31 standing upright toward the upper side of the motorcycle 1. In other words, the center line of the cylinder bore 31a of the engine 17 may face in the vertical direction of the motorcycle 1. The cylinder 31 and the cylinder head 33 of the engine 17 are arranged directly under the seat 37 or directly under the storage box 38 provided under the seat 37.

An intake passage structure 41 for supplying intake air to the engine 17 is provided between the engine 17 and the seat 37 and inside the vehicle body cover 9. The intake passage structure 41 includes an air cleaner 42 that filters outside air to obtain clean intake air, and an intake passage 43 that guides the intake air purified by the air cleaner 42 to the engine 17.

The intake passage 43 connects the air cleaner 42 and the engine 17. The intake passage 43 guides intake air from the air cleaner 42 to the engine 17. The intake passage 43 includes an inlet tube 45 connected to the air cleaner 42, a throttle body 46 connected to the downstream end of the inlet tube 45 to adjust the flow rate of intake air supplied to the engine 17, and a downstream end of the throttle body 46. The intake manifold 47, which is connected to the intake manifold 47, is provided.

The air cleaner 42 is arranged behind the cylinder head 33 of the engine 17. That is, the air cleaner 42 causes the intake air to flow out toward the front. The intake passage 43 guides the intake air discharged forward by the air cleaner 42 to the cylinder head 33 of the engine 17.

The throttle body 46 is arranged between the inlet tube 45 and the intake manifold 47. The throttle body 46 includes a linear intake passage (not shown) and a throttle valve (butterfly valve, not shown) arranged in the intake passage.

The vehicle body cover 9 arranges the appearance of the motorcycle 1 to protect internal equipment. The vehicle body cover 9 contains a plurality of synthetic resin molded products that are connected to each other.

Next, the intake passage structure 41 of the engine 17 will be described in detail.

FIG. 2 is a cross-sectional view of the intake passage structure of the engine according to the embodiment of the present invention.

Note that FIG. 2 is a cross-sectional view taken through the center of the mainstream passage 68 in the intake manifold 47.

As shown in FIG. 2, the intake passage 43 of the intake passage structure 41 according to the present embodiment connects the air cleaner 42 and the combustion chamber 51 of the engine 17. The intake passage 43 guides intake air from the air cleaner 42 to the combustion chamber 51 of the engine 17.

In addition to the inlet tube 45, the throttle body 46, and the intake manifold 47, the intake passage 43 includes a fuel injection device 52 provided in the intake manifold 47 to inject fuel into the intake air, and an intake port 53 of the cylinder head 33. It is provided with a branch passage portion 55 that bypasses a part of the intake air from the upstream side to the downstream side of the position where the fuel is injected into the intake air.

In the engine 17 according to the present embodiment, the center line C of the cylinder bore 31a is directed in the front-rear direction of the motorcycle 1. The inlet 53a of the intake port 53 of the engine 17 is open on the upper surface of the cylinder head 33. The outlet 53b of the intake port 53 is connected to the combustion chamber 51. The outlet 53b of the intake port 53 is opened and closed by the intake valve 56.

The cylinder head 33 is provided with an exhaust port 57. The inlet 57a of the exhaust port 57 is connected to the combustion chamber 51. The inlet 57a of the exhaust port 57 is opened and closed by the exhaust valve 58. The outlet 57b of the exhaust port 57 is open to the lower surface of the cylinder head 33. An exhaust pipe (not shown) and a muffler (silencer) are sequentially connected to the exhaust port 57.

An insulator 61 is provided between the throttle body 46 and the intake manifold 47.

The intake manifold 47 is connected to the intake port 53 of the cylinder head 33. The intake manifold 47 guides the intake air purified by the air cleaner 42 and whose flow rate is adjusted by the throttle body 46 to the intake port 53. The intake manifold 47 is a pipe that is curved or bent in an arc shape, and is a so-called elbow. The intake manifold 47 includes a flange portion 62 fixed to the intake port 53 of the engine 17. A gasket 63 is sandwiched between the intake port 53 and the flange portion 62.

The intake manifold 47 has an upstream straight portion 65 connected to the throttle body 46 and extending linearly, a downstream straight portion 66 connected to the intake port 53 of the cylinder head 33 and extending linearly, and an upstream straight portion 65. It has a curved portion 67 which is provided between the straight portion 66 and the downstream straight portion 66 and is curved in an arc shape.

The upstream straight portion 65, the curved portion 67, and the downstream straight portion 66 circulate most of the intake air passing through the intake manifold 47. The flow path in the upstream straight portion 65, the curved portion 67, and the downstream straight portion 66 is referred to as a mainstream passage 68 of the intake manifold 47.

The upstream straight line portion 65 is substantially linearly connected to the intake passage of the throttle body 46. The upstream straight line portion 65 extends toward the front of the motorcycle 1.

The downstream straight line portion 66 is connected to the intake port 53 of the engine 17. The upstream straight line portion 65 extends downward of the motorcycle 1.

The portion of the curved portion 67 near the center of curvature is referred to as "inside of the curved portion 67", and the portion of the curved portion 67 far from the center of curvature is referred to as "outside of the curved portion 67".

Further, the intake manifold 47 has a recessed portion 69 that dents a part of the wall surface of the intake passage 43 in a direction intersecting the flow direction of the intake air.

The recessed portion 69 straddles the curved portion 67 and the downstream straight portion 66. The recessed portion 69 causes the intake manifold 47 to bulge toward the outside of the curved portion 67. The recessed space 71 partitioned by the recessed portion 69 is recessed toward the outside of the curved portion 67 and reaches (crosses) the downstream straight portion 66. The recessed space 71 extends the mainstream passage 68 of the intake manifold 47 toward the outside of the curved portion 67.

The recessed portion 69 has a bottom wall portion 72 to which the fuel injection device 52 is fixed, and a side wall portion 73 interposed between the bottom wall portion 72, the curved portion 67, and the downstream straight portion 66. .. The bottom wall portion 72 is provided with a fuel injection device insertion hole 76 for inserting the fuel injection port 75 of the fuel injection device 52 into the intake manifold 47.

The inner surface of the bottom wall portion 72, that is, the bottom surface portion 72a of the recessed portion 69 faces the intake port 53 arranged below the intake manifold 47. That is, the bottom surface portion 72a according to the present embodiment faces downward.

The inner surface of the side wall portion 73, that is, the side surface portion 73a extends toward the intake port 53 substantially orthogonal to the edge of the bottom surface portion 72a.

The fuel injection device 52 injects fuel into the intake air, that is, the air flowing through the intake passage 43. The fuel injected from the fuel injection device 52 and the intake air are mixed to form an air-fuel mixture. The fuel injection device 52 is provided on the intake manifold 47. The fuel injection device 52 is provided on the downstream side straight portion 66 near the outside of the curved portion 67 of the intake manifold 47 or the outside of the curved portion 67 of the intake manifold 47.

The fuel injection device 52 has a fuel injection port 75 for injecting fuel into the intake air. The fuel injection port 75 is exposed in the intake manifold 47 in the middle of the mainstream passage 68 and faces the mainstream passage 68. The fuel injection port 75 is arranged below the intake manifold 47 from the fuel injection device 52 provided on the downstream straight portion 66 near the outside of the curved portion 67 of the intake manifold 47 or the outside of the curved portion 67 of the intake manifold 47. It faces the intake port 53. That is, the fuel injection port 75 according to the present embodiment faces downward. The fuel injection port 75 faces the valve fillet 77 of the intake valve 56.

Further, the fuel injection port 75 is exposed in the intake manifold 47 through the fuel injection device insertion hole 76 of the bottom wall portion 72 of the recessed portion 69.

By the way, since the intake manifold 47 has the curved portion 67, the flow of the intake air in the mainstream passage 68 increases the flow velocity outside the curved portion 67 rather than inside the curved portion 67. Then, the fuel injected from the fuel injection port 75 to the intake air in the mainstream passage 68 is swept to the outside of the curved portion 67 where the flow velocity increases, and the outside of the curved portion 67 in the inner wall surface of the mainstream passage 68. And approaches the outside of the downstream straight line portion 66 continuous to the outside of the curved portion 67. Therefore, the intake passage structure 41 according to the present embodiment is provided with a branch passage portion 55 in the intake manifold 47 to prevent fuel approaching the inner wall surface of the mainstream passage 68 from adhering to the inner wall surface of the mainstream passage 68.

FIG. 3 is a cross-sectional view of the intake passage structure of the engine according to the embodiment of the present invention.

Note that FIG. 3 is a cross-sectional view of the branch passage portion 55 passing through the center of the passage.

As shown in FIG. 3 in addition to FIG. 2, the branch passage portion 55 of the intake passage structure 41 according to the present embodiment is integrally molded with the intake manifold 47. The branch passage portion 55 branches a part of the intake air flowing through the intake manifold 47. That is, the branch passage portion 55 diverts a part of the intake air flowing through the mainstream passage 68. The branch passage portion 55 diverts a part of the intake air from the mainstream passage 68, bypasses the fuel injection port 75, and returns a part of the divided intake air to the downstream side of the fuel injection port 75.

The branch passage portion 55 has a branch passage inlet 81 arranged on the upstream side of the fuel injection port 75 and a branch passage outlet 82 arranged on the downstream side of the fuel injection port 75 and attached to the fuel injection port 75. is doing. In other words, the fuel injection port 75 is located between the branch passage inlet 81 and the branch passage outlet 82 in the direction of the intake air flow of the mainstream passage 68 (that is, the intake flow of the intake manifold 47 passing through other than the branch passage portion 55). Have been placed.

The branch passage inlet 81 is provided in the vicinity of the upstream end of the curved portion 67 of the intake manifold 47. The branch passage outlet 82 is provided in the vicinity of the downstream end of the curved portion 67 of the intake manifold 47.

Further, the branch passage inlet 81 is provided outside the curved portion 67 of the intake manifold 47. The branch passage outlet 82 is provided outside the curved portion 67 of the intake manifold 47. The branch passage inlet 81 and the branch passage outlet 82 are substantially open in the tangential direction of the intake manifold 47. The branch passage inlet 81 and the branch passage outlet 82 are substantially open in the tangential direction outside the curved portion 67.

The branch passage inlet 81 is open toward the upstream of the intake air flow toward the fuel injection port 75.

FIG. 4 is a cross-sectional view of the intake passage structure of the engine according to the embodiment of the present invention in the IV-IV line of FIG.

In addition to FIGS. 2 and 3, as shown in FIG. 4, the branch passage outlet 82 of the intake passage structure 41 according to the present embodiment opens toward the downstream direction of the intake air flow away from the fuel injection port 75. There is. The branch passage outlet 82 is provided on the bottom surface portion 72a of the recessed portion 69. That is, the recessed portion 69 has a bottom surface portion 72a in which the fuel injection port 75 and the branch passage outlet 82 are arranged, and a side surface portion 73a including a portion 69a arranged on the downstream side of the branch passage outlet 82. ing.

The branch passage outlet 82 is attached to the fuel injection port 75 of the fuel injection device 52. Here, "attached to the fuel injection port 75" means the fuel injection device insertion hole 76 of the intake manifold 47 and the wall (the wall of the recessed portion 69 and the wall of the branch passage portion 55) attached to the insertion hole 76. ), As long as the appropriate strength is secured or as long as it can be processed, the closer it is, the better. For example, when viewed from the opening direction of the fuel injection port 75, the opening direction of the fuel injection device insertion hole 76, or the opening direction of the branch passage outlet 82, the branch passage outlet 82 has an opening diameter thereof from the center of the fuel injection port 75. It is preferable that the circular region A having twice the diameter of the fuel injection device or the center of the fuel injection device insertion hole 76 penetrates into the inside of the circular region A having a diameter twice the opening diameter.

The branch passage outlet 82 is farther from the center of the mainstream passage 68 than the fuel injection port 75. In other words, the branch passage outlet 82 is closer to the portion 69a farthest from the center of the mainstream passage 68 in the side wall portion 73 of the recessed portion 69 than the fuel injection port 75. This guides a part of the intake air flowing out from the branch passage outlet 82 to the portion 69a in the side wall portion 73 of the recessed portion 69, which is farther from the center of the mainstream passage 68 than the fuel injection port 75, and heads toward the intake port 53. Create a wall of air. Even if the fuel injected from the fuel injection port 75 is pushed toward the outside of the curved portion 67 by the intake air flowing through the mainstream passage 68, the air wall allows the fuel to be pushed to the inner surface of the intake manifold 47 (fuel injection port 75). It diffuses before reaching the inner surface on the downstream side. At this time, the air wall is generated from the inside of the recessed space 71 of the recessed portion 69 as a starting point. This air wall prevents the fuel injected from the fuel injection port 75 from entering the recessed space 71, and the fuel injected from the fuel injection port 75 is an intake manifold 47 including the side wall portion 73 of the recessed portion 69. Prevents it from adhering to the inner surface of the fuel.

Further, the branch passage portion 55 includes an upstream straight passage 83 extending linearly from the branch passage inlet 81 and a downstream straight passage 84 connected to the upstream straight passage 83 and extending linearly toward the branch passage exit 82. Have.

FIG. 5 is a view of the intake manifold of the intake passage structure according to the embodiment of the present invention as viewed from the opening on the upstream side.

In addition to FIGS. 2 and 3, as shown in FIG. 5, the upstream straight passage 83 of the intake passage structure 41 according to the present embodiment extends in the tangential direction of the intake manifold 47 at the branch passage inlet 81. The upstream side straight passage 83 opens in the tangential direction outside the curved portion 67 at the branch passage entrance 81. The upstream side straight passage 83 can be seen from the opening on the upstream side of the intake manifold 47. Therefore, the upstream side straight passage 83 can be easily machined by inserting a tool such as a drill through the opening on the upstream side of the intake manifold 47.

FIG. 6 is a perspective sectional view passing through the center line of the straight passage on the downstream side of the branch passage portion of the intake passage structure according to the embodiment of the present invention.

In addition to FIGS. 2 and 3, as shown in FIG. 6, the downstream straight passage 84 of the intake passage structure 41 according to the present embodiment extends in the tangential direction of the intake manifold 47 at the branch passage outlet 82. The downstream straight passage 84 opens in the tangential direction outside the curved portion 67 at the branch passage outlet 82. The downstream straight passage 84 can be seen from the downstream opening of the intake manifold 47 or the downstream edge of the recessed space 71 of the recessed portion 69. Therefore, the downstream straight passage 84 can be easily machined by inserting a tool such as a drill through the opening on the downstream side of the intake manifold 47.

FIG. 7 is a view of the intake manifold of the branch passage portion of the intake passage structure according to the embodiment of the present invention as viewed from the outside of the curved portion.

FIG. 8 is a view of the intake manifold of the branch passage portion of the intake passage structure according to the embodiment of the present invention as viewed from the normal direction of a virtual plane passing through the mainstream passage.

As shown in FIGS. 7 and 8, in addition to FIGS. 2 and 3, the fuel injection device 52 of the intake passage structure 41 according to the present embodiment is based on a virtual plane P passing through the center of the intake passage 43. Is arranged on one side of the plane P, or on one side of the plane P while straddling the plane P. The branch passage portion 55 is arranged on the other side of the plane P.

The upstream straight passage 83 of the branch passage portion 55 is biased to the left side of the virtual plane P passing through the center of the intake passage 43 in the plan view of the motorcycle 1. Then, the upstream side straight passage 83 passes forward on the left side of the fuel injection device 52 in the plan view of the motorcycle 1. The downstream side straight passage 84 of the branch passage portion 55 extends toward the lower right so as to go around the front of the fuel injection device 52.

When viewed from the normal direction of the plane P passing through the center line of the intake passage 43 (FIG. 8), the branch passage portion 55 overlaps the fuel injection device 52.

Further, when viewed from the normal direction of the plane P passing through the center line of the intake passage 43 (FIG. 8), the direction orthogonal to the connecting surface 62a of the flange portion 62 on the downstream side of the intake manifold 47 and away from the flange portion 62. In (the solid line arrow in the figure), the portion 55a of the branch passage portion 55 farthest from the engine 17 is closer to the engine 17 than the portion 52a of the fuel injection device 52 farthest from the engine 17. In other words, the portion 55a of the branch passage portion 55 farthest from the engine 17 in the direction orthogonal to the coupling surface 62a of the flange portion 62 on the downstream side of the intake manifold 47 and away from the flange portion 62 is the engine of the fuel injection device 52. It is closer to the flange portion 62 on the downstream side of the intake manifold 47 than the portion 52a farthest from 17. It should be noted that FIG. 8 shows a one-dot chain line L1 that is parallel to the mounting surface of the engine 17 and passes through the portion 52a of the fuel injection device 52 that is farthest from the engine 17.

Further, when viewed from the normal direction of the plane P passing through the center line of the intake passage 43 (FIG. 8), the portion 55b farthest from the intake manifold 47 of the branch passage portion 55 is the most from the intake manifold 47 of the fuel injection device 52. It is closer to the intake manifold 47 than the distant part 52b. Note that FIG. 8 shows a alternate long and short dash line L2 that is perpendicular to the mounting surface of the engine 17 and passes through a portion 52b that is farthest from the intake manifold 47 of the fuel injection device 52.

Further, when viewed from the normal direction of the plane P passing through the center line of the intake passage 43, the branch passage is orthogonal to the connecting surface 62a of the flange portion 62 on the downstream side of the intake manifold 47 and is away from the flange portion 62. The portion 55a of the portion 55 farthest from the engine 17 is closer to the engine 17 than the portion 47a of the intake manifold 47 farthest from the engine 17. In other words, the portion 55a of the branch passage portion 55 farthest from the engine 17 in the direction orthogonal to the coupling surface 62a of the flange portion 62 on the downstream side of the intake manifold 47 and away from the flange portion 62 is the engine 17 of the intake manifold 47. It is closer to the flange portion 62 on the downstream side of the intake manifold 47 than the portion 47a farthest from the intake manifold 47. Note that FIG. 8 shows a alternate long and short dash line L3 that is parallel to the mounting surface of the engine 17 and passes through the portion 47a of the intake manifold 47 that is farthest from the engine 17.

In other words, the branch passage portion 55 extends along the intake passage 43 through a path that does not protrude from the fuel injection device 52 that is attached so as to project into the intake passage 43.

FIG. 9 is a cross-sectional view passing through the center line of the upstream side straight passage of the branch passage portion of the intake passage structure according to the embodiment of the present invention.

As shown in FIG. 9, the upstream side straight passage 83 of the intake passage structure 41 according to the present embodiment has a substantially uniform passage break in the entire length from the branch passage inlet 81 to the downstream straight passage 84. Has an area.

Further, the upstream side straight passage 83 may have a tapered portion 86 in which the cross-sectional area of the flow path decreases from the branch passage inlet 81 toward the downstream, as shown by the alternate long and short dash line in FIG. Further, the upstream side straight passage 83 is continuous with the branch passage inlet 81, and the flow path cross section is steeply narrowed from a large diameter portion (not shown) having a flow path cross section equivalent to that of the branch passage inlet 81. It may have a stepped portion (not shown). In these cases, the opening area of the branch passage inlet 81 is larger than the flow path cross section in the middle of the branch passage portion 55.

The intake manifold 47 may be integrally molded with the cylinder head 33 of the engine 17. That is, the intake manifold 47 and the intake port 53 of the cylinder head 33 may be integrally molded. In this case, the intake manifold 47 and the intake port 53 of the cylinder head 33 according to the present embodiment are simply referred to as intake ports. A fuel injection device 52 is provided at this intake port, and a branch passage portion 55 is integrally formed.

Further, the intake manifold 47 may be a straight tube. For example, in a motorcycle 1 that linearly supplies intake air downward from an air cleaner 42 to an intake port 53 of an engine 17, such as a super sports type motorcycle 1, a branch passage is provided to a linear intake manifold 47. The portion 55 may be provided. In this case, the opening direction of the branch passage inlet 81, the opening direction of the branch passage exit 82, the extending direction of the upstream straight passage 83, and the extending direction of the downstream straight passage 84 are the center lines of the mainstream passage 68 of the intake manifold 47 ( It is preferable that the angle formed between the straight line substantially extending in the vertical direction is shallow (small).

The intake passage structure 41 of the engine 17 according to the present embodiment is arranged at the branch passage inlet 81 arranged on the upstream side of the fuel injection port 75 and on the downstream side of the fuel injection port 75 and is attached to the fuel injection port 75. It has a branch passage outlet 82 and includes a branch passage portion 55 through which a part of the intake air is circulated. Therefore, in the intake passage structure 41, even if the fuel injected from the fuel injection device 52 is about to be pushed to the wall surface of the mainstream passage 68 by the intake air flowing through the mainstream passage 68, the intake passage structure 41 moves from the branch passage portion 55 to the mainstream passage 68. The inflowing intake air pushes the fuel downstream before reaching the wall surface of the mainstream passage 68. That is, in the intake passage structure 41, the fuel injected from the fuel injection device 52 is less likely to adhere to the wall surface of the mainstream passage 68. Therefore, the intake passage structure 41 can stabilize the air-fuel ratio of the air-fuel mixture.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has a branch passage inlet 81 that opens in the upstream direction of the intake flow toward the fuel injection port 75. Therefore, the intake passage structure 41 can smoothly guide the intake air flowing along the wall surface of the intake passage 43 to the branch passage portion 55.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has an opening area of the branch passage inlet 81 larger than the flow path cross-sectional area in the middle of the branch passage portion 55. Therefore, the intake passage structure 41 can supply more intake air to the branch passage outlet 82 as compared with the case where the cross section of the flow path is constant or the opening area of the branch passage inlet 81 is smaller. That is, in the intake passage structure 41, the fuel injected from the fuel injection device 52 is less likely to adhere to the wall surface of the mainstream passage 68.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has a tapered portion 86 in which the cross-sectional area of the passage decreases from the branch passage inlet 81 toward the downstream. Therefore, the intake passage structure 41 can more smoothly supply more intake air to the branch passage outlet 82. That is, the intake passage structure 41 makes it more difficult for the fuel injected from the fuel injection device 52 to more reliably adhere to the wall surface of the mainstream passage 68.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has a branch passage outlet 82 that opens toward the downstream direction of the intake flow away from the fuel injection port 75. Therefore, the intake passage structure 41 can smoothly send the intake air flowing through the branch passage portion 55 toward the wall surface of the intake passage 43. Therefore, the intake passage structure 41 can more reliably flush the fuel toward the wall surface of the mainstream passage 68 toward the downstream direction of the intake air flowing through the mainstream passage 68.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has a recessed portion 69 that dents a part of the wall surface of the intake passage 43 in a direction intersecting the flow direction of the intake air. Therefore, in the intake passage structure 41, the fuel injected from the fuel injection device 52 does not easily reach the outer wall surface of the mainstream passage 68, and the adhesion of the fuel to the wall surface can be easily prevented.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment includes a branch passage portion 55 that overlaps with the fuel injection device 52 when viewed from the normal direction of the plane P. In other words, the branch passage portion 55 does not project toward the periphery of the fuel injection device 52 (direction away from the intake manifold 47). Therefore, the intake passage structure 41 is unlikely to be affected by the installation space (competition for the installation space) on the surrounding structures and electric products.

Further, in the intake passage structure 41 of the engine 17 according to the present embodiment, when viewed from the normal direction of the plane P passing through the center of the intake passage 43, the portion 55a of the branch passage portion 55 farthest from the engine 17 is fuel-injected. It is closer to the engine 17 than the part 52a farthest from the engine 17 of the device 52. Therefore, the intake passage structure 41 can prevent the branch passage portion 55 from projecting around the fuel injection device 52, particularly in a direction away from the intake passage 43.

Further, in the intake passage structure 41 of the engine 17 according to the present embodiment, when viewed from the normal direction of the plane P passing through the center of the intake passage 43, the portion 55a of the branch passage portion 55 farthest from the engine 17 is the intake manifold. It is closer to the engine 17 than the part 47a farthest from the engine 17 of 47. Therefore, the intake passage structure 41 can prevent the branch passage portion 55 from projecting around the intake manifold 47, particularly in the direction in which the intake passage 43 extends.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has a branch passage inlet 81 and a branch passage outlet 82 that open in the tangential direction of the intake manifold 47. Therefore, when the intake manifold 47 is curved, the intake passage structure 41 can smoothly guide the intake air flowing along the wall surface of the intake passage 43 to the branch passage portion 55, while to the wall surface of the mainstream passage 68. The heading fuel can be more reliably swept downstream of the intake air flowing through the mainstream passage 68.

Further, the intake passage structure 41 of the engine 17 according to the present embodiment has an upstream side straight passage 83 and a downstream side straight passage 84 connected to the upstream side straight passage 83. The branch passage portion 55 is a straight road without a branch in addition to the upstream straight passage 83 and the downstream straight passage 84. Therefore, the intake passage structure 41 can join the intake air flowing through the mainstream passage 68 without reducing the momentum of the intake air flowing through the branch passage portion 55. Further, the intake passage structure 41 can easily form the branch passage portion 55.

Therefore, according to the intake passage structure 41 of the engine 17 according to the present embodiment, the adhesion of fuel to the inner wall surface of the intake passage 43 is more reliably suppressed, and the air-fuel ratio of the air-fuel mixture is stabilized.

1 ... motorcycle, 3 ... body frame, 5 ... power unit, 6 ... steering mechanism, 7 ... front wheel, 8 ... rear wheel, 9 ... body cover, 11 ... front fork, 12 ... front fender, 13 ... handle bar, 15 ... Grip, 17 ... engine, 18 ... link mechanism, 23 ... power transmission device, 27 ... rear cushion unit, 31 ... cylinder, 31a ... cylinder bore, 32 ... crank case, 33 ... cylinder head, 35 ... head cover, 37 ... seat, 38 ... storage box, 41 ... intake passage structure, 42 ... air cleaner, 43 ... intake passage, 45 ... inlet tube, 46 ... throttle body, 47 ... intake manifold, 47a ... farthest part from engine, 51 ... combustion chamber, 52 ... fuel injection device, 52a ... farthest part from engine, 52b ... farthest part from intake manifold, 53 ... intake port, 53a ... inlet, 53b ... exit, 55 ... branch passage, 55a ... part, 56 ... intake valve, 57 ... Exhaust port, 57a ... Inlet, 57b ... Outlet, 58 ... Exhaust valve, 61 ... Insulator, 62 ... Flange part, 62a ... Joint surface, 63 ... Gasket, 65 ... Upstream straight part, 66 ... Downstream straight part, 67 ... Curved portion, 68 ... Mainstream passage, 69 ... Recessed portion, 69a ... Recessed portion, portion arranged downstream from the branch passage exit, 71 ... Recessed space, 72 ... Bottom wall portion, 72a ... Bottom surface Cylinder, 73 ... Side wall, 73a ... Side, 75 ... Fuel injection port, 76 ... Fuel injection device insertion hole, 77 ... Valve fillet, 81 ... Branch passage inlet, 82 ... Branch passage exit, 83 ... Upstream straight passage, 84 ... Downstream straight passage, 86 ... Tapered part.

Claims (8)

It is an engine intake passage structure equipped with an intake passage that guides intake air to the combustion chamber of the engine.
The intake passage is
The throttle body that adjusts the flow rate of the intake air and
An intake manifold connected to the downstream end of the throttle body and curved in an arc shape,
A fuel injection device having a fuel injection port for injecting fuel to the intake and provided in the intake manifold, and a fuel injection device.
The intake manifold is provided with a branch passage inlet arranged on the upstream side of the fuel injection port and a branch passage outlet arranged on the downstream side of the fuel injection port and attached to the fuel injection port. A branch passage portion that circulates a part of the intake air in the intake manifold, and
It has a recessed portion that dents a part of the wall surface of the intake passage in a direction intersecting the flow direction of the intake air .
The intake manifold has an upstream straight portion connected to the throttle body and extending linearly, a downstream straight portion connected to the intake port of the engine and extending linearly, an upstream straight portion and the downstream side. It has a curved portion that is provided between the straight portion and curves in an arc shape, and has a curved portion.
The downstream straight section is outside the downstream projection of the upstream straight section, and the upstream straight section is outside the upstream projection of the downstream straight section.
The fuel injection device is provided on the downstream side straight portion near the outside of the curved portion of the intake manifold or the outside of the curved portion of the intake manifold.
The recessed portion has a bottom surface portion on which the fuel injection port and the branch passage outlet are arranged, and a side surface portion including a portion arranged on the downstream side of the branch passage outlet.
The branch passage inlet and the branch passage exit are opened in the tangential direction of the curved portion of the intake manifold.
The branch passage outlet is located farther from the center of the passage in the intake manifold than the fuel injection port and between the fuel injection port and the side surface portion of the recessed portion.
The branch passage portion is an intake engine having an upstream side straight passage that extends linearly from the branch passage inlet and a downstream side straight passage that is connected to the upstream side straight passage and extends linearly toward the branch passage exit. Passage structure. The intake passage structure of an engine according to claim 1, wherein the branch passage inlet opens toward the upstream direction of the intake flow toward the fuel injection port. The intake passage structure of the engine according to claim 1 or 2, wherein the opening area of the branch passage inlet is larger than the flow path cross-sectional area in the middle of the branch passage. The intake passage structure of an engine according to claim 3, wherein the branch passage portion has a tapered portion in which the cross-sectional area of the flow path becomes smaller from the entrance of the branch passage toward the downstream side. The intake passage structure of an engine according to any one of claims 1 to 4, wherein the branch passage outlet opens toward the downstream direction of the intake flow away from the fuel injection port. With reference to the plane passing through the center of the intake passage
The fuel injection device is arranged on one side of the plane.
The branch passage portion is arranged on the other side of the plane and overlaps with the fuel injection device when viewed from the normal direction of the plane.
The intake passage structure of an engine according to any one of claims 1 to 5 , wherein the branch passage outlet is closer to the combustion chamber of the engine than the branch passage inlet . When viewed from the normal direction of the plane passing through the center of the intake passage, the portion of the branch passage portion farthest from the engine is closer to the engine than the portion of the fuel injection device farthest from the engine. The intake passage structure of the engine according to any one of 6 to 6 . The intake passage has an intake manifold provided with the fuel injection port and having the branch passage portion.
From claim 1, the portion of the branch passage portion farthest from the engine when viewed from the normal direction of the plane passing through the center of the intake passage is closer to the engine than the portion of the intake manifold farthest from the engine. 7. The intake passage structure of the engine according to any one of 7.

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