WO2024069940A1

WO2024069940A1 - Air intake structure for internal combustion engine

Info

Publication number: WO2024069940A1
Application number: PCT/JP2022/036727
Authority: WO
Inventors: 直道香取
Original assignee: 本田技研工業株式会社
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2024-04-04

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

Intake structure of an internal combustion engine

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 is connected to each cylinder and introduces intake air.

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 off from the intake passage that connects to the cylinders of the internal combustion engine and introduces intake air, thereby reducing intake noise.

Japan Patent Publication No. 2011-94633

In the present technology for improving fuel efficiency, an internal combustion engine having a structure for generating a tumble flow requires a larger intake volume to generate the tumble flow, and therefore requires a resonator with a large volume. In particular, in an internal combustion engine having multiple cylinders and multiple intake ports, a resonator is required for each intake port, which causes the internal combustion engine to become bulky.
In order to solve the above problems, the present application has an object to provide an internal combustion engine that can be downsized and at the same time reduce costs, thereby contributing to improved energy efficiency.

In view of the above problems, the present invention provides an intake passage for introducing air from an air cleaner to a combustion chamber,
a fuel injection device for supplying 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 a tumble flow and a tumble valve downstream of the throttle valve;
and a resonator downstream of the tumble valve for connecting a plurality of intake passages to each other.

With the above configuration, the resonator that connects the multiple intake passages to each other is located downstream of the tumble valve, so the flow rate of the tumble flow can be increased. This allows intake to be performed with the mixture stirred, making it possible to achieve a favorable combustion state in the internal combustion engine. This not only improves fuel efficiency and reduces unburned gas, but also reduces the cost of an exhaust gas catalytic device. In addition, 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, so it is possible to reduce the size of the internal combustion engine while reducing costs.

In the above configuration, the resonator has a resonator chamber located at the center and a communication hole 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.

With the above configuration, the resonator chamber has a larger volume than the communication hole, so a tumble flow can be formed in good response to changes in the throttle valve opening, the tumble valve, and engine speed. This allows the intake to be performed with the mixture more agitated, resulting in a more optimal combustion state. This leads to improved fuel efficiency and reduced unburned gas, as well as reduced costs for the catalytic converter. Furthermore, this results in an internal combustion engine with good response during acceleration.

In the above configuration, the resonator has a resonator chamber located at the center and a communication hole connecting the plurality of intake passages and the resonator chamber,
The resonator chamber may include an inner wall (46a) that forms an arc along the plurality of intake passages.

With this configuration, the volume of the resonator chamber can be made as large as possible, so that a tumble flow can be formed in good response to changes in the throttle valve opening, the tumble valve, and engine speed. This allows the intake to be performed with the mixture more agitated, resulting in a more optimal combustion state. This leads to improved fuel efficiency and reduced unburned gas, while also reducing the cost of the catalytic device. Furthermore, this results in an internal combustion engine with good response during acceleration.

The present invention can suppress the enlargement of an internal combustion engine that has multiple cylinders and generates a tumble flow by providing a resonator without providing a resonator for each intake port.

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. FIG. 1 is a vertical sectional view of a main portion of an internal combustion engine. FIG. 2 is a bottom view of the cylinder head of the internal combustion engine. FIG. 2 is a schematic diagram of an intake structure of an internal combustion engine. FIG. 2 is an exploded perspective view of a main part of the intake structure. FIG. 2 is a longitudinal cross-sectional view taken perpendicular to the intake air flow of the connecting pipe. FIG. 8 is a cross-sectional view taken along the line VIII in FIG. 7 .

FIG. 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. The 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 does not have to be a motorcycle, but may be any vehicle equipped with an internal combustion engine, and is not limited to motorcycles.

The body frame 110 of the motorcycle 100 includes a head pipe 111 that steers the front fork 102 that pivots around the front wheel 101, a pair of left and right main frame members 112 that extend downward to the rear 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 parts of the left and right main frame members 112 and extend downward to the rear below the main frame members 112, a pair of left and right pivot frame members 114 that are connected to the rear end of the main frame members 112 and extend downward, and a pair of left and right seat rails 115 that extend upward to the rear from the rear parts of the main frame members 112.

The internal combustion engine 1 is mounted on a vehicle body frame 110, 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 supported by the pivot frame member 114, extends rearward, and a rear wheel 104 is supported by its rear end. An endless drive chain 66 is wound around a drive sprocket 65 fitted to the output shaft 64 of the internal combustion engine 1 and a driven sprocket 105 fitted to the rear axle.

An air cleaner 106 is disposed above the internal combustion engine 1, positioned behind the head pipe 111 of 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 part of the air cleaner 106. Behind the fuel tank 107, a main seat 108 is supported by seat rails 115.

As shown in FIG. 2, which is a left side view of the internal combustion engine 1, the internal combustion engine 1 is provided with a transmission 60 in a crankcase 2, constituting a so-called power unit. The internal combustion engine 1 is a four-stroke internal combustion engine equipped with 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.

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

As shown in Figure 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 Figure 1) tilted forward.

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.

The crankshaft 20 is rotatably supported by the crankcase 2, and a transmission 60 is built in behind the crankshaft 20. The main shaft 61 of the transmission 60 is equipped with a clutch device (not shown) at its right end and is axially mounted parallel to the crankshaft 20, and a countershaft 62 is supported slightly behind it and parallel to the crankshaft 20 at 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.

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 fitted so as to be able to slide freely 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.

As shown in FIG. 3, the cylinder head 4 is formed with an intake port 10 and an exhaust port 11 that are connected to the combustion chamber 9. The internal combustion engine 1 is a four-valve internal combustion engine with two intake valves 17 and two exhaust valves 18 per cylinder 7. The cylinder head 4 is provided with the intake valves 17 and exhaust valves 18, which respectively control 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.

Figure 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, there are two intake valve ports 9b through which the intake valve 17 opens and closes, and two exhaust valve ports 9c through which the exhaust valve 18 opens and closes, lined up side by side.

The combustion chamber ceiling surface 9a is a dome-shaped concave curved surface, with the intake valve ports 9b opening side by side on roughly the rear half of the combustion chamber ceiling surface 9a, and the exhaust valve ports 9c opening side by side on roughly 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.

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.

Referring to Figure 4, the

intake ports

10, 10 extending rearward from the

intake valve openings

9b, 9b arranged to the left and right are gathered on the upstream side. As shown in Figure 3, a connecting pipe 40 is connected to the upstream end of the intake port 10.

As shown in FIG. 4,

exhaust ports

11, 11 extending forward from

exhaust valve ports

9c, 9c arranged side by side are gathered on the downstream side. As shown in FIG. 3, an exhaust pipe 13 is connected to the downstream end of the exhaust port 11.

As shown in FIG. 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 portion facing the combustion chamber 9.

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 the umbrella portion 17u at the tip of the valve stem 17s opens and closes the intake valve port 9b.

The exhaust valve 18 is similarly supported so that the valve stem 18s can slide freely on a valve guide 23 that is fitted into the upper wall of the exhaust port 11, and the head portion 18u at the tip of the valve stem 18s opens and closes the exhaust valve port 9c.

The valve mechanism that drives the intake valve 17 and exhaust valve 18 is of the DOHC type. As the parallel intake camshaft 71 and exhaust camshaft 72 rotate, the intake cam 73 on the intake camshaft 71 and the exhaust cam 74 on the exhaust camshaft 72 push the

valve lifters

75, 75 that are placed on the upper ends of the intake valve 17 and exhaust valve 18, respectively, causing the intake valve 17 and 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 exhaust valve port 9c.

The upstream end of the intake port 10 is connected to a connecting pipe 40 that draws in outside air. The upstream end of the connecting pipe 40 is connected to an intake pipe 56 with a tumble valve 57 inside, and a throttle body 54 with a throttle valve 55.

As shown in FIG. 1, an air funnel 35 is attached upstream of the throttle body 54. The air funnel 35 is fitted and opened inside 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 the intake passage 30.

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.

An exhaust pipe 13 is connected to the exhaust port 11, and a catalytic device 26 containing a three-way catalyst or the like is arranged 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 device 26, and muffler 14 form an exhaust passage 16.

Then, in the intake passage 30, the intake passage that runs 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 part of the intake pipe 56 to the curved part of the intake port 10 into a main passage 30A and a tumble passage 30B, each of which is defined to have a roughly semicircular cross section.

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 57.

The intake pipe 56 is fitted with a fuel injection valve 22 that is positioned to penetrate the main passage 30A from the outside above and supply fuel by injecting it.

FIG. 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 composed of a first intake passage 31 and a second intake passage 32. The first intake passage 31 and the second intake passage 32 each have 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 FIGS. 5 and 6).

As shown in FIG. 6, the connecting pipe 40 has 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 respective outer

peripheral wall sections

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.

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 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 flow direction.

The interior partitioned by the first circular tube portion 41, the second circular tube portion 42, and the pair of connecting walls 43 forms the resonator chamber 46. The wall surface of the first circular tube portion 41 between the pair of connecting walls 43 forms the partition wall portion 41c that partitions the first intake passage 31 and the resonator chamber 46. The wall surface of the second circular tube portion 42 between the pair of connecting walls 43 forms the partition wall portion 42c that partitions the second intake passage 32 and the resonator chamber 46. As shown in FIG. 7, these

partition wall portions

41c, 42c form the inner wall 46a of the resonator chamber 46 that is in an arc shape that follows the first intake passage 31 and the second intake passage 32. Since the inner wall 46a is formed in an arc shape that follows the first intake passage 31 and the second intake passage 32, it is possible to arrange the resonator chamber 46 large.

The first gasket 51 and the second gasket 52 that contact the downstream end and the upstream end of the connecting pipe 40 are plate-shaped members.

The first gasket 51 has a first main flow passage opening 51aA, a first tumble flow passage opening 51aB, a second main flow passage opening 51bA, and a second tumble flow passage opening 51bB, which correspond to the first main flow passage 31A, the first tumble flow passage 31B, and the second main flow passage 32A, the second tumble flow passage 32B.

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

The central parts of the first gasket 51 and the second gasket 52

form blocking parts

51c, 52c that close both ends of the resonator chamber 46 of the connecting tube, and the resonator chamber 46 is formed by the

partition wall parts

41c, 42c and the blocking

parts

51c, 52c that cover both ends.

As shown in Figures 7 and 8, the

partition walls

41c and 42c have communication holes 47 that connect the resonator chamber 46 to the first tumble flow path 31B and the second tumble flow path 32B, respectively, and the resonator chamber 46 and the communication hole 47c form the resonator 45. The volume of the communication hole 47 is set to be smaller than the volume of the resonator chamber 46.

The intake structure of the internal combustion engine of this embodiment is configured as described above, and therefore provides the following effects.

The intake structure of the internal combustion engine of this embodiment is a multiple cylinder internal combustion engine equipped with an intake passage 30 that introduces air from an air cleaner 106 to a combustion chamber 9, a fuel injection device 22 that supplies fuel to the intake passage 30, and a throttle valve 55 that adjusts the air flow rate introduced into the combustion chamber 9. The intake structure of the internal combustion engine of this embodiment is equipped with a first intake passage 31 and a second intake passage 32 for generating a tumble flow downstream of the throttle valve 55, a resonator 45 having a tumble valve 57 and connecting the first intake passage 31 and the second intake passage 32 to each other downstream of the tumble valve 57. Since the resonator 45 that connects the multiple intake passages to each other is arranged downstream of the tumble valve 57, the flow rate of the tumble flow can be increased. Therefore, the intake can be performed in a state where the mixture is stirred, and the combustion of the internal combustion engine 1 can be made into a suitable combustion state. Therefore, it is possible to improve fuel efficiency and reduce unburned gas, and it is possible to suppress the cost of the exhaust gas catalytic device 26. In addition, since the resonator 45 is located 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 allows for a smaller internal combustion engine 1 while reducing costs.

Furthermore, the resonator 45 has a resonator chamber 46 located in the center and a communication hole 47 that connects the first intake passage 31, the second intake passage 32, and the resonator chamber 46. Since the volume of the resonator chamber 46 is larger than the volume of the communication hole 47, a tumble flow can be formed in good response to changes in the opening of the throttle valve 55, the tumble valve 57, and the engine speed. This makes it possible to perform intake with a more agitated mixture, resulting in a more optimal combustion state. This leads to improved fuel efficiency and reduced unburned gas, as well as reduced costs for the catalytic device 26. Furthermore, the internal combustion engine 1 has good responsiveness during acceleration.

Furthermore, the resonator 45 has a resonator chamber 46 located in the center and a communication hole 47 that connects the first intake passage 31 and the second intake passage 32. The resonator chamber 46 has an inner wall 46a that is arc-shaped and follows the first intake passage 31 and the second intake passage 32. This allows the volume of the resonator chamber 46 to be as large as possible, so that a tumble flow can be formed in good response to changes in the opening of the throttle valve 55, the tumble valve 57, and the engine speed. This allows the intake to be performed with the mixture more agitated, resulting in a more optimal combustion state. This leads to improved fuel efficiency and reduced unburned gas, as well as reduced costs for the catalytic converter. Furthermore, the internal combustion engine has good response during acceleration.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various design changes are possible without departing from the gist of the invention. Of course, the gist of the present invention includes vehicles, internal combustion engines, etc. implemented in various forms. For example, the embodiment of the present invention employs a DOHC type valve train, but is not limited to this.

1 ... internal combustion engine, 7 ... 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

an intake passage (30) for introducing air from an air cleaner (106) into a 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);
and 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),
2. The intake structure of an internal combustion engine according to claim 1, wherein a volume of the resonator chamber (46) is larger than a volume of the communication hole (47).
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 of an internal combustion engine according to claim 1, wherein the resonator chamber (46) has an arc-shaped inner wall (46a) that fits along the plurality of intake passages (31, 32).