Intake structure of an internal combustion engine

Abstract

Disclosed is an air intake structure for an internal combustion engine having a plurality of cylinders 7, the air intake structure comprising an air intake passage 30 through which air is introduced from an air cleaner 106 into a combustion chamber 9, a fuel injection device 22 that supplies a fuel to the air intake passage 30, and a throttle valve 55 that adjusts the flow rate of the air introduced into the combustion chamber 9, wherein: the air intake structure has, downstream of the throttle valve 55, a tumble valve 57 and a plurality of air intake passages 31, 32 for generating a tumble flow; the air intake structure is provided with a resonator 45 by which the plurality of air intake passages 31, 32 communicate with one another, the resonator 45 being provided downstream of the tumble valve 57; and even when the resonator is provided to the internal combustion engine, which has a plurality of cylinders and in which a tumble flow is generated, the air intake structure makes it possible to suppress any increase in the size of the internal combustion engine without providing a resonator to each air intake port.

Description

[Technical Field]

[0001] The present invention relates to an intake structure for an internal combustion engine having multiple cylinders, in which a resonator is provided in an intake passage that communicates with each cylinder and introduces intake air. [Background technology]

[0002] In recent years, research and development has been conducted into improving fuel efficiency, which contributes to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy.Conventionally, an intake structure for an internal combustion engine is known in which a resonator is provided branching from the intake passage that communicates with the cylinders of the internal combustion engine and introduces intake air, thereby reducing intake noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japan Patent Publication No. 2011-94633 Summary of the Invention [Problem to be solved by the invention]

[0004] In this technology for improving fuel efficiency, an internal combustion engine equipped with a structure for generating a tumble flow requires a large amount of intake air to generate the tumble flow, which necessitates a resonator with a large volume. In particular, in an internal combustion engine with multiple cylinders and multiple intake ports, a resonator is required for each intake port, which poses a problem of the internal combustion engine becoming larger. In order to solve the above problems, the present application aims to provide an internal combustion engine that can be downsized and reduced in cost, thereby contributing to improved energy efficiency. [Means for solving the problem]

[0005] In view of the above, the present invention provides an intake passage for introducing air from an air cleaner into a combustion chamber; a fuel injection device that supplies fuel to the intake passage; a throttle valve for adjusting the flow rate of air introduced into the combustion chamber; In an intake structure of a multiple cylinder internal combustion engine, a plurality of intake passages for generating tumble flow and a tumble valve downstream of the throttle valve; and a resonator downstream of the tumble valve that connects the plurality of intake passages to one another.

[0006] According to the above configuration, the resonator that connects the multiple intake passages to each other is located downstream of the tumble valve, which increases the tumble flow rate. This allows the intake of air in a stirred air-fuel mixture, resulting in favorable combustion conditions in the internal combustion engine. This improves fuel efficiency, reduces unburned gas emissions, and reduces the cost of an exhaust gas catalytic converter. Furthermore, since the resonator is located between the multiple intake passages, there is no need to provide a resonator downstream of the tumble valve for each cylinder, which allows for a more compact internal combustion engine while reducing costs.

[0007] In the above configuration, the resonator has a resonator chamber located at the center and communication holes connecting the plurality of intake passages and the resonator chamber, The volume of the resonator chamber may be larger than the volume of the communication hole.

[0008] According to the above configuration, the resonator chamber has a larger volume than the communication hole, so a tumble flow can be generated in good response to changes in the throttle valve opening, the tumble valve, and engine speed. This allows the intake of a more agitated air-fuel mixture, resulting in a more optimal combustion state. This leads to improved fuel efficiency, reduced unburned gas, and reduced costs for the catalytic converter. Furthermore, the internal combustion engine has good responsiveness during acceleration.

[0009] In the above configuration, the resonator has a resonator chamber located at the center and communication holes connecting the plurality of intake passages and the resonator chamber, The resonator chamber may include an inner wall (46a) that is arcuate and extends along the plurality of intake passages.

[0010] According to the above configuration, the volume of the resonator chamber can be maximized, thereby enabling the formation of a tumble flow in a responsive manner to changes in the throttle valve opening, the tumble valve, and engine speed. This allows the intake of a more agitated air-fuel mixture, resulting in a more optimal combustion state. This leads to improved fuel economy, reduced unburned gas, and reduced costs for the catalytic converter. Furthermore, the internal combustion engine exhibits excellent responsiveness during acceleration. [Effects of the Invention]

[0011] The present invention can suppress enlargement of the internal combustion engine even when a resonator is provided in an internal combustion engine having a plurality of cylinders and generating a tumble flow, without providing a resonator for each intake port. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an enlarged side view of a motorcycle equipped with an intake structure for an internal combustion engine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a left side view of the internal combustion engine. [Figure 3]1 is a longitudinal sectional view of a main part of an internal combustion engine. [Figure 4] FIG. 2 is a bottom view of the cylinder head of the internal combustion engine. [Figure 5] FIG. 1 is a schematic diagram of an intake structure of an internal combustion engine. [Figure 6] FIG. 2 is an exploded perspective view of a main part of the intake structure. [Figure 7] FIG. 2 is a longitudinal cross-sectional view taken perpendicular to the intake air flow of the connecting pipe. [Figure 8] FIG. 8 is a cross-sectional view taken along the arrow VIII in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 shows a left side view of a motorcycle 100 to which an intake structure for an internal combustion engine according to an embodiment of the present invention is applied. Motorcycle 100 is shown as an example of a vehicle equipped with an internal combustion engine 1 according to the present invention, and the vehicle is not limited to a motorcycle as long as it is equipped with an internal combustion engine.

[0014] The body frame 110 of the motorcycle 100 includes a head pipe 111 that steersably supports a front fork 102 that pivotally supports the front wheel 101, a pair of left and right main frame members 112 that extend rearward and downward from the head pipe 111, a pair of left and right engine hangers 113 that are connected to the head pipe 111 and the front portions of the left and right main frame members 112 and extend rearward and downward below the main frame members 112, a pair of left and right pivot frame members 114 that are connected to the rear end portions of the main frame members 112 and extend downward, and a pair of left and right seat rails 115 that extend rearward and upward from the rear portions of both main frame members 112.

[0015] The internal combustion engine 1 is mounted on a body frame 110 and suspended from the front and rear by an engine hanger 113 and a pivot frame member 114 below a main frame member 112. A swing arm 103, whose front end is journaled on the pivot frame member 114, extends rearward and whose rear end journaled a rear wheel 104, and an endless drive chain 66 is wound around a drive sprocket 65 fitted onto an output shaft 64 of the internal combustion engine 1 and a driven sprocket 105 fitted onto the rear axle.

[0016] An air cleaner 106 is disposed above the internal combustion engine 1 so as to be located rearward of a head pipe 111 on the body frame 110. A fuel tank 107 of a fuel supply device 120 is mounted on both main frame members 112 of the body frame 110 so as to cover the rear and upper portion of the air cleaner 106. A main seat 108 is provided behind the fuel tank 107 and supported by seat rails 115.

[0017] As shown in Fig. 2, which is a left side view of the internal combustion engine 1, the internal combustion engine 1 forms a so-called power unit that includes a transmission 60 in a crankcase 2. The internal combustion engine 1 is a four-stroke internal combustion engine that includes two cylinders 7. In this embodiment, two cylinders 7 are formed, but it is not limited to two, and it is sufficient that two or more cylinders are provided.

[0018] The internal combustion engine 1 is mounted on a vehicle body frame 110 with the crankshaft 20 oriented in the vehicle width direction (left-right direction).

[0019] As shown in Fig. 3, the internal combustion engine 1 has a crankcase 2 divided into an upper crankcase 2A and a lower crankcase 2B. A cylinder block 3 is integrally formed at the front upper portion of the upper crankcase 2A, with the cylinder axes Lc of two cylinders 7 (only the left cylinder 7 is shown in Fig. 1) tilted forward.

[0020] A cylinder head 4 is placed on and fastened to the cylinder block 3, and a cylinder head cover 5 is placed on top of the cylinder head 4. An oil pan 6 is attached below the crankcase 2.

[0021] A crankshaft 20 is rotatably supported by the crankcase 2, and a transmission 60 is built in behind the crankshaft 20. A main shaft 61 of the transmission 60 is provided with a clutch device (not shown) on its right end and is disposed parallel to the crankshaft 20, and a countershaft 62 is disposed slightly behind the main shaft 61 and is supported parallel to the crankshaft 20 on the upper and lower joining surfaces 2a of the crankcase 2. As shown in FIG. 1, the aforementioned drive sprocket 65 is fitted to the left end of the countershaft 62 that protrudes through the crankcase 2, and the countershaft 62 forms the output shaft 64 of the internal combustion engine 1.

[0022] As shown in Fig. 2, a cylinder 7 is formed in the cylinder block 3 of the internal combustion engine 1, and a piston 8 that reciprocates within the cylinder 7 is slidably fitted within the cylinder 7. A combustion chamber 9 is formed by the cylinder 7, the top surface of the piston 8, and the underside of the cylinder head 4 that faces the top surface of the piston 8. As shown in Fig. 3, an ignition plug 19 is attached to the cylinder head 4 so that its tip faces the combustion chamber 9.

[0023] As shown in Figure 3, the cylinder head 4 is formed with an intake port 10 and an exhaust port 11 that communicate with the combustion chamber 9. The internal combustion engine 1 is a four-valve internal combustion engine that has two intake valves 17 and two exhaust valves 18 per cylinder 7. The intake valves 17 and exhaust valves 18 are arranged in the cylinder head 4, and each of these valves controls the amount of intake air flowing from the intake port 10 to the combustion chamber 9 and the amount of exhaust air discharged from the combustion chamber 9 to the exhaust port 11.

[0024] 4 is a bottom view of the cylinder head 4 as seen from the mating surface 4a side with the cylinder block 3. In the combustion chamber ceiling surface 9a facing the piston top surface of the cylinder head 4, two intake valve ports 9b through which the intake valves 17 open and close and two exhaust valve ports 9c through which the exhaust valves 18 open and close are opened side by side.

[0025] The combustion chamber ceiling surface 9a is a dome-shaped concave curved surface, with intake valve ports 9b opening side by side on the rear half of the combustion chamber ceiling surface 9a, and exhaust valve ports 9c opening side by side on the front half of the combustion chamber ceiling surface 9a. The inner diameter of the exhaust valve ports 9c is smaller than the inner diameter of the intake valve ports 9b.

[0026] As shown in FIG. 3, the cylinder head 4 has an intake port 10 that curves rearward and extends from the intake valve port 9b, and an exhaust port 11 that curves forward and extends from the exhaust valve port 9c.

[0027] 4, intake ports 10, 10 extending rearward from intake valve openings 9b, 9b arranged side by side are gathered on the upstream side. As shown in FIG. 3, a connecting pipe 40 is connected to the upstream end of the intake port 10.

[0028] As shown in Figure 4, exhaust ports 11, 11 extending forward from the exhaust valve ports 9c, 9c arranged side by side are gathered on the downstream side. As shown in Figure 3, an exhaust pipe 13 is connected to the downstream end of the exhaust port 11.

[0029] 4, a spark plug hole 4b into which an ignition plug 19 is screwed is provided in the center of the combustion chamber ceiling surface 9a of each combustion chamber 9 in the cylinder head 4 near the cylinder axis Lc, and intake valve ports 9b, 9b and exhaust valve ports 9c, 9c are opened widely around the spark plug hole 4b. The spark plug 19 screwed into the spark plug hole 4b in the center of the combustion chamber ceiling surface 9a has its tip electrode facing the combustion chamber 9.

[0030] As shown in FIG. 3, the intake valve 17 has a valve stem 17s slidably supported by a valve guide 23 fitted to the upper wall of the intake port 10, and an umbrella portion 17u at the tip of the valve stem 17s opens and closes the intake valve port 9b.

[0031] Similarly, the exhaust valve 18 has a valve stem 18s slidably supported by a valve guide 23 fitted to the upper wall of the exhaust port 11, and an umbrella portion 18u at the tip of the valve stem 18s opens and closes the exhaust valve port 9c.

[0032] The valve train that drives the intake valve 17 and the exhaust valve 18 is of the DOHC type. As the intake camshaft 71 and the exhaust camshaft 72, which are parallel to each other, rotate, an intake cam 73 attached to the intake camshaft 71 and an exhaust cam 74 attached to the exhaust camshaft 72 push valve lifters 75, 75 attached to the upper ends of the intake valve 17 and the exhaust valve 18, respectively. This causes the intake valve 17 and the exhaust valve 18 to reciprocate at a predetermined timing according to the rotational position of the crankshaft 20, opening and closing the intake valve port 9b and the exhaust valve port 9c.

[0033] A connecting pipe 40 that draws in outside air is connected to the upstream end of the intake port 10. An intake pipe 56 with a tumble valve 57 disposed therein and a throttle body 54 with a throttle valve 55 disposed therein are connected to the upstream end of the connecting pipe 40.

[0034] As shown in Figure 1, an air funnel 35 is attached to the upstream side of the throttle body 54. The air funnel 35 is fitted into and opens onto the clean side of an air cleaner 106 that purifies outside air, and the purified intake air is sent to the internal combustion engine 1. The intake port 10, connecting pipe 40, intake pipe 56, throttle body 54, and air funnel 35 form an intake passage 30.

[0035] The throttle valve 55 is rotatably supported within the throttle body 54 by a throttle valve shaft 55a that is oriented approximately horizontally and perpendicular to the flow direction of the intake passage 30, and variably controls the passage area of ​​the intake passage 30 to adjust the amount of intake air from the upstream side.

[0036] An exhaust pipe 13 is connected to the exhaust port 11, and a catalytic converter 26 incorporating a three-way catalyst or the like is disposed midway through the exhaust pipe 13 to purify the exhaust gas. The downstream end of the exhaust pipe 13 is connected to a muffler 14, which reduces exhaust noise. The exhaust port 11, exhaust pipe 13, catalytic converter 26, and muffler 14 form an exhaust passage 16.

[0037] In the intake passage 30, the intake passage extending from the intake pipe 56 to the intake port 10 via the connecting pipe 40 is divided by a partition wall 33 from the downstream portion of the intake pipe 56 to the curved portion of the intake port 10 into a main passage 30A and a tumble passage 30B, each of which has an approximately semicircular cross section.

[0038] The tumble passage 30B is rotatably supported by a tumble valve 57a that is parallel to the throttle valve shaft 55a, and the flow rate is changed by the tumble valve 57a.

[0039] A fuel injection valve 22 is attached to the intake pipe 56 so as to penetrate the main passage 30A from above and outside and to inject and supply fuel.

[0040] Figure 5 is a schematic diagram showing the intake structure of the internal combustion engine of this embodiment. The internal combustion engine of this embodiment is a two-cylinder internal combustion engine, and the intake passage 30 is made up of a first intake passage 31 and a second intake passage 32. Each of the first intake passage 31 and the second intake passage 32 is equipped with a throttle valve 55 and a tumble valve 57 to control the intake. The connecting pipe 40 is connected to the intake port 10 via a first gasket 51 and an O-ring 53, and to the intake pipe 56 via a second gasket 52 and an O-ring 53, respectively (see Figures 5 and 6).

[0041] 6, the connecting pipe 40 includes a first circular pipe section 41 that constitutes the first intake passage 31 and a second circular pipe section 42 that constitutes the second intake passage. The first circular pipe section 41 and the second circular pipe section 42 are arranged so that the central axes of the circular pipes are approximately parallel, and the outer peripheral walls 41a, 42a of the first circular pipe section 41 and the second circular pipe section 42 are connected by a pair of connecting walls 43.

[0042] The first circular pipe section 41 is divided by a partition plate section 41b into a first main flow path 31A and a first tumble flow path 31B in the intake air flow direction. The second circular pipe section 42 is also divided by a partition plate section 42b into a second main flow path 32A and a second tumble flow path 32B in the intake air flow direction.

[0043] The interior defined by the first circular pipe portion 41, the second circular pipe portion 42, and the pair of connecting walls 43 constitutes a resonator chamber 46. The wall surface of the first circular pipe portion 41 between the connecting walls 43 constitutes a partition wall 41c that separates the first intake passage 31 and the resonator chamber 46. The wall surface of the second circular pipe portion 42 between the connecting walls 43 constitutes a partition wall 42c that separates the second intake passage 32 and the resonator chamber 46. As shown in FIG. 7 , the partition walls 41c, 42c form an arc-shaped inner wall 46a of the resonator chamber 46 that conforms to the first intake passage 31 and the second intake passage 32. Because the inner wall 46a is formed in an arc-like shape that conforms to the first intake passage 31 and the second intake passage 32, the resonator chamber 46 can be made large.

[0044] The first gasket 51 and the second gasket 52 that are brought into contact with the downstream end and the upstream end of the connecting pipe 40 are plate-shaped members.

[0045] The first gasket 51 has a first main flow path opening 51aA, a first tumble flow path opening 51aB, a second main flow path opening 51bA, and a second tumble flow path opening 51bB corresponding to the first main flow path 31A, the first tumble flow path 31B, the second main flow path 32A, and the second tumble flow path 32B.

[0046] Similarly, the second gasket 52 is provided with a first main flow path opening 52aA, a first tumble flow path opening 52aB, a second main flow path opening 52bA, and a second tumble flow path opening 52bB corresponding to the first main flow path 31A, the first tumble flow path 31B, the second main flow path 32A, and the second tumble flow path 32B.

[0047] The central portions of the first gasket 51 and the second gasket 52 form blocking portions 51c, 52c that close both ends of the resonator chamber 46 of the connecting pipe, and the resonator chamber 46 is formed by the partition wall portions 41c, 42c and the blocking portions 51c, 52c that cover these both ends.

[0048] 7 and 8, the partition walls 41c and 42c have communication holes 47 as communication portions that respectively connect the resonator chamber 46 with the first tumble flow path 31B and the second tumble flow path 32B, and the resonator chamber 46 and the communication hole 47c form the resonator 45. The volume of the communication hole 47 is set smaller than the volume of the resonator chamber 46.

[0049] The intake structure for an internal combustion engine according to this embodiment is configured as described above, and therefore provides the following effects.

[0050] The intake structure for an internal combustion engine according to this embodiment is a multi-cylinder internal combustion engine including an intake passage 30 that introduces air from an air cleaner 106 into a combustion chamber 9, a fuel injector 22 that supplies fuel to the intake passage 30, and a throttle valve 55 that adjusts the flow rate of air introduced into the combustion chamber 9. The intake structure further includes a first intake passage 31 and a second intake passage 32 downstream of the throttle valve 55 for generating a tumble flow, a tumble valve 57, and a resonator 45 downstream of the tumble valve 57 that connects the first intake passage 31 and the second intake passage 32 to each other. Since the resonator 45 that connects the multiple intake passages to each other is located downstream of the tumble valve 57, the flow rate of the tumble flow can be increased. This allows intake to be performed in a stirred air-fuel mixture, resulting in a favorable combustion state in the internal combustion engine 1. This improves fuel efficiency, reduces unburned gas emissions, and reduces the cost of the exhaust gas catalytic converter 26. Furthermore, since the resonator 45 is provided between the first intake passage 31 and the second intake passage 32, there is no need to provide a resonator 45 downstream of the tumble valve 57 for each cylinder, which makes it possible to reduce the size of the internal combustion engine 1 while also reducing costs.

[0051] Furthermore, the resonator 45 has a centrally located resonator chamber 46 and a communication hole 47 connecting the first intake passage 31, the second intake passage 32, and the resonator chamber 46. The volume of the resonator chamber 46 is larger than the volume of the communication hole 47, so that a tumble flow can be generated in good response to changes in the opening of the throttle valve 55, the tumble valve 57, and engine speed. This allows the intake of a more agitated air-fuel mixture, resulting in a more optimal combustion state. This further improves fuel efficiency, reduces unburned gas, and reduces the cost of the catalytic converter 26. Furthermore, the internal combustion engine 1 can be made to have good responsiveness during acceleration.

[0052] Furthermore, the resonator 45 has a centrally located resonator chamber 46 and a communication hole 47 connecting the first intake passage 31 and the second intake passage 32. The resonator chamber 46 has an arc-shaped inner wall 46a that conforms to the first intake passage 31 and the second intake passage 32. This maximizes the volume of the resonator chamber 46, allowing for the formation of a tumble flow that responds quickly to changes in the opening of the throttle valve 55, the tumble valve 57, and engine speed. This allows for the intake of a more agitated air-fuel mixture, resulting in a more optimal combustion state. This results in improved fuel economy, reduced unburned gas emissions, and reduced costs for catalytic converters. Furthermore, the engine exhibits excellent responsiveness during acceleration.

[0053] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible without departing from the spirit of the present invention. Of course, the present invention includes vehicles, internal combustion engines, and the like that are embodied in various forms within the spirit of the present invention. For example, although a DOHC type valve train is used in the embodiments of the present invention, the present invention is not limited to this. [Explanation of symbols]

[0054] 1... internal combustion engine, 7... cylinder (cylinder), 9... combustion chamber, 22...Fuel injection device, 30...intake passage, 31...first intake passage, 32...second intake passage, 45... resonator, 46... resonator chamber, 46a... inner wall, 47... communication hole, 55...throttle valve, 57...tumble valve, 106...Air cleaner.

Claims

1. an intake passage (30) for introducing air from an air cleaner (106) into the combustion chamber (9); a fuel injection device (22) that supplies fuel to the intake passage (30); a throttle valve (55) for adjusting the flow rate of air introduced into the combustion chamber (9); In an intake structure of an internal combustion engine having a plurality of cylinders (7), a plurality of intake passages (31, 32) for generating a tumble flow and a tumble valve (57) are provided downstream of the throttle valve (55); a resonator (45) downstream of the tumble valve (57) for connecting the plurality of intake passages (31, 32) to each other; The resonator (45) has a resonator chamber (46) located at the center and a communication hole (47) connecting the plurality of intake passages (31, 32) to the resonator chamber (46), The air intake structure for an internal combustion engine is characterized in that the resonator chamber (46) has an arc-shaped inner wall (46a) that is aligned with the plurality of air intake passages (31, 32).

2. The resonator (45) has a resonator chamber (46) located at the center and a communication hole (47) connecting the plurality of intake passages (31, 32) to the resonator chamber (46), 2. The intake structure for an internal combustion engine according to claim 1, wherein the volume of the resonator chamber (46) is larger than the volume of the communication hole (47).

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