WO2022176862A1

WO2022176862A1 - Air intake structure for internal combustion engine

Info

Publication number: WO2022176862A1
Application number: PCT/JP2022/006018
Authority: WO
Inventors: 洋平中村
Original assignee: 本田技研工業株式会社
Priority date: 2021-02-19
Filing date: 2022-02-15
Publication date: 2022-08-25
Also published as: JP7403708B2; JPWO2022176862A1

Abstract

The purpose of the present disclosure is to provide an internal combustion engine configured such that an air intake passage is divided by a partitioning part, and it is possible to ensure both an intake air volume and tumbling performance in accordance with an operation state. An air intake structure S of the internal combustion engine according to one embodiment comprises: a main partitioning part 62 for partitioning an air intake passage connected to a combustion chamber of the internal combustion engine into a first air intake passage 64 and a second air intake passage 66 on a first direction side of the first air intake passage, where the first direction is defined as being from a crankshaft side to a cylinder head side in the direction of a cylinder axis C; a secondary partitioning part 72 provided to the first air intake passage so as to form a third air intake passage 68 and a fourth air intake passage 70 on the first direction side of the third air intake passage; and a merging part 86 where the third air intake passage and the fourth air intake passage merge, and the first air intake passage merges into the second air intake passage via the merging part.

Description

Intake structure of internal combustion engine

The present invention relates to an intake structure for an internal combustion engine provided with partitions for dividing an intake passage into a plurality of sections.

Various intake structures for internal combustion engines have been proposed in which the intake passage on the downstream side of the throttle valve is divided into a plurality of passages by partitions. For example, in the intake structure for an internal combustion engine disclosed in Patent Document 1, a tumble valve is provided downstream of the throttle valve, and a partition plate portion, which is a partition portion, is provided downstream of the tumble valve from the inlet pipe to the intake port, The partition plate partitions the intake passage into a lower secondary passage and an upper main passage. The lower secondary passage serves as a tumble passage, and the tumble valve substantially opens and closes the upper main passage.

Further, in the internal combustion engine disclosed in Patent Document 2, an intake control valve is provided downstream of the throttle valve, and a horizontal plate-shaped member is disposed along the flow direction of the intake air in the intake passage downstream of the throttle valve. ing. An internal combustion engine with one horizontal plate member and two or more horizontal plate members are disclosed. According to the description of Patent Document 2, by forming a plurality of horizontal plate-shaped members and determining the opening degree of the intake control valve according to the operating conditions of the internal combustion engine, the amount of intake air is reduced even at intermediate opening degrees of the intake control valve. Generates a stable gas flow without disturbing the flow.

Japanese Patent No. 6714764 Japanese Patent Application Laid-Open No. 2006-77590

By the way, in order to operate the internal combustion engine properly, it is necessary to secure an intake air amount corresponding to the operating state of the internal combustion engine, and to suitably generate a swirling flow such as a tumble flow in the combustion chamber in order to increase the combustion efficiency. It is desirable to be compatible with However, for example, the configuration of Patent Document 2 is mainly aimed at realizing an intake air amount according to the operating state, and has a problem in maintaining tumble performance even when the engine load fluctuates, for example. SUMMARY OF THE INVENTION An object of the present invention is to provide an internal combustion engine in which an intake passage is divided by a partition portion, and which is capable of ensuring both an intake air amount according to the operating state and tumble performance. It is in.

In order to achieve the above object, one aspect of the present invention is
When defining the direction of the cylinder axis from the crankshaft side to the cylinder head side as the first direction, the intake passage leading to the combustion chamber of the internal combustion engine is called the first intake passage, and the first intake passage on the first direction side of the first intake passage. a main partition partitioning into two intake passages;
a sub-partition provided in the first intake passage so as to form a third intake passage and a fourth intake passage on the first direction side of the third intake passage;
a confluence portion where the third intake passage and the fourth intake passage merge, and the merge portion through which the first intake passage merges with the second intake passage. An intake structure for an internal combustion engine characterized by:

According to the above configuration, the intake passage can be divided into the first intake passage including the third intake passage and the fourth intake passage that can be a tumble flow passage, and the second intake passage. By using any one or all of them, it becomes possible to secure the intake flow rate according to the operating state. Further, according to the above configuration, since the confluence portion is provided, it is possible to impart strong directivity to the intake air from the first intake passage having the third intake passage and the fourth intake passage, thereby ensuring tumble performance. can do. Therefore, according to the intake structure of the internal combustion engine, it is possible to secure both the intake air amount according to the operating state and the tumble performance in the internal combustion engine configured so that the intake passage is divided by the partition. becomes possible.

Preferably, the confluence portion is connected to the second intake passage on the downstream side of the downstream end of the main partition portion. With this configuration, the intake air passing through the first intake passage can have strong directivity.

Preferably, the merging portion is defined so that the intake air from the first intake passage through the merging portion flows into the combustion chamber at a smaller entrance angle than the intake air from the second intake passage. there is With this configuration, the intake air that has passed through the first intake passage can be introduced into the combustion chamber while maintaining strong directivity, so that a strong tumble flow can be generated in the combustion chamber.

Preferably, the confluence section is formed so that the cross-sectional area of each of the third intake passage and the fourth intake passage is smaller than the cross-sectional area of the upstream end of the confluence section. With this configuration, the intake air from the third intake passage and the intake air from the fourth intake passage preferably flow into the confluence portion, thereby ensuring a sufficient intake air flow rate.

Preferably, the cross-sectional area of the merging portion in a cross section perpendicular to the flow direction on the downstream side of the upstream end of the merging portion is greater than the sum of the cross-sectional areas of the third intake passage and the fourth intake passage. The confluence is partitioned so as to be small. With this configuration, when the intake air from the third intake passage and the intake air from the fourth intake passage merge at the confluence portion and flow into the second intake passage, the flow velocity of the intake air can be kept high.

Preferably, when the direction opposite to the first direction in the direction of the cylinder axis is defined as the second direction, the first intake passage is sectioned to have a convex curved shape in the second direction. , the second intake passage is formed to have a curved shape convex in the first direction. With this configuration, it becomes possible to guide the intake air from the first intake passage to the combustion chamber at a smaller entrance angle, and to more effectively guide the intake air from the second intake passage to the combustion chamber. .

Preferably, the intake structure for the internal combustion engine described above further includes an intake control valve provided upstream of the main partition. In this case, the intake control valve is configured to be able to open and close the second intake passage and the fourth intake passage, and the first position to close the second intake passage and the fourth intake passage. It is preferable to have a second position in which the second intake passage is closed and the fourth intake passage is opened, and a fully open position. With this configuration, it is possible to more preferably secure an intake air amount according to the operating state while appropriately generating a tumble flow.

Preferably, the intake control valve is provided with a single valve member that rotates about a valve shaft, and the concave portion that allows the movement of the valve member defines the first portion of the wall portion that partitions and forms the intake passage. It is provided on the wall on the one direction side. With this configuration, the amount of intake air can be more easily adjusted by controlling the movement of a single valve member, and the recess can improve the opening and closing function of the valve member. .

The intake structure of the internal combustion engine described above may include a plurality of the sub-partitions. In this case, the first intake passage may be divided into three or more intake passages including the third intake passage and the fourth intake passage by a plurality of sub-partitions. With this configuration, it becomes possible to finely adjust the amount of intake air according to the operating state.

According to the above aspect of the present invention, since it has the above configuration, in an internal combustion engine configured such that the intake passage is divided by the partition portion, it is possible to ensure both the intake air amount according to the operating state and the tumble performance. can be preferably achieved.

FIG. 1 is a schematic configuration diagram of an internal combustion engine according to one embodiment of the present invention. FIG. 2 is a diagram showing a three-dimensional model of the portion of the intake passage on the downstream side of the throttle valve in the internal combustion engine of FIG. FIG. 3 is a view of the three-dimensional model of FIG. 2, viewed from an angle different from that of FIG. FIG. 4 is a diagram showing a valve body of a tumble valve in the internal combustion engine of FIG. 1. FIG. FIG. 5 is a top view of a three-dimensional model including an intake passage portion and an exhaust port on the downstream side of the throttle valve and the downstream side of the tumble valve in the internal combustion engine of FIG. FIG. 6 is a view of the three-dimensional model of FIG. 5 viewed from a direction perpendicular to the cylinder axis C and the direction of the intake air flow. 7A is a cross-sectional view of the three-dimensional model of FIG. 6, and is a cross-sectional view along the line VIIA-VIIA of FIG. 6. FIG. 7B is a cross-sectional view of the three-dimensional model of FIG. 6, and is a cross-sectional view along line VIIB-VIIB of FIG. 6. FIG. 7C is a cross-sectional view of the three-dimensional model of FIG. 6, and is a cross-sectional view along line VIIC-VIIC of FIG. 6. FIG. 7D is a cross-sectional view of the three-dimensional model of FIG. 6, and is a cross-sectional view along line VIID-VIID of FIG. 6. FIG.

Hereinafter, an embodiment according to the present invention will be described based on the accompanying drawings. The same parts (or configurations) are given the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

A schematic configuration of an internal combustion engine 10 according to one embodiment of the present invention is shown in FIG. FIG. 1 is a cross-sectional view of an internal combustion engine 10 along an axis (cylinder axis) C of a cylinder bore 12b of a cylinder block 12 of the internal combustion engine 10. FIG. The internal combustion engine 10 is a single-cylinder engine, and has a single intake valve 46 and a single exhaust valve 50 for each cylinder.

A piston 15 that reciprocates in the cylinder bore 12b of the cylinder block 12 is connected to the crankpin of the crankshaft 17 of the crankcase portion 16 by a connecting rod 18. A combustion chamber 20 is formed between the top surface 15a of the piston 15 slidably fitted in the cylinder bore 12b of the cylinder block 12 and the combustion chamber ceiling surface 14a of the cylinder head 14 facing the top surface 15a. be.

The internal combustion engine 10 employs a SOHC type two-valve system, and a valve mechanism 22 is provided in the cylinder head 14 . A cylinder head cover 24 is overlaid on the cylinder head 14 so as to cover the valve mechanism 22 . In order to transmit power to the valve mechanism 22 in the cylinder head cover 24, an endless cam chain (not shown) is provided on one side of the crankcase portion 16, the cylinder block 12, and the cylinder head 14 in the crankshaft direction. A camshaft 26 and a crankshaft 17 are installed through a cam chain chamber, and the camshaft 26 rotates in synchronism with the crankshaft 17 at a rotation speed of 1/2. An ignition plug is inserted into the combustion chamber 20 from the opposite side of the cam chain chamber (the other side in the crankshaft direction) of the cylinder head 14 .

In the cylinder head 14, from an intake valve port 28 and an exhaust valve port 30 that open to the ceiling surface 14a of the combustion chamber, an intake port 32 and an exhaust port 34 are formed so as to extend while curving in directions vertically separating from each other. The upstream end of the intake port 32 opens toward the upper side of the cylinder head 14 and is connected to an inlet pipe 36 to form a continuous intake passage 38. A throttle body 40 is connected to the upstream side of the inlet pipe 36. be.

The downstream end of the exhaust port 34 opens downward from the cylinder head 14 and is connected to the exhaust pipe 42 . An exhaust purification device and a silencer may be provided downstream of the exhaust pipe 42 .

A cylindrical intake valve guide 44 is integrally fitted to the curved outer wall portion 32a of the intake port 32 in the cylinder head 14. An intake valve 46 slidably supported by an intake valve guide 44 opens and closes an intake valve port 28 of the intake port 32 facing the combustion chamber 20 .

Also, an exhaust valve 50 slidably supported by an exhaust valve guide 48 integrally fitted to the curved outer wall portion 34a of the exhaust port 34 in the cylinder head 14 is an exhaust valve opening facing the combustion chamber 20 of the exhaust port 34. Open and close 30.

The intake valve 46 and the exhaust valve 50 are biased upward by valve springs so that the

head portions

46a and 50a thereof close the intake valve opening 28 and the exhaust valve opening 30 facing the combustion chamber 20, respectively. Stem ends 46b and 50b of the intake valve 46 and the exhaust valve 50 are pushed down by an intake rocker arm 56 and an exhaust rocker arm 58 that contact and oscillate with the intake cam and the exhaust cam of the camshaft 26, and the intake valve 46 and the exhaust valve 50 are opened at a predetermined timing. The exhaust valve 50 opens, the intake port 32 communicates with the combustion chamber 20, and the exhaust port 34 communicates with the combustion chamber 20, and intake and exhaust are performed at predetermined timings.

An inlet pipe 36 is connected to the upstream end of the intake port 32 of the internal combustion engine 10 via an insulator 60 to form a continuous intake passage 38. A throttle body 40 is connected to the upstream side of the inlet pipe 36. be done. The throttle body 40 has an intake passage 40a with a substantially circular cross section forming part of the intake passage 38 communicating with the combustion chamber 20 of the internal combustion engine 10, and the upstream side of the intake passage 40a is connected to an air cleaner device (not shown).

The throttle body 40 is rotatably supported in the throttle body 40 by a throttle valve shaft 40b that intersects the central axis of the intake passage 40a at right angles to the flow direction of intake air in the intake passage 40a. It has a throttle valve 40c that can variably control the flow passage area of the air intake passage 40a to open and close the intake passage 40a. The throttle valve 40c is of the butterfly type, and has a throttle valve shaft 40b and a disk-shaped valve body 40d that is fixed to the throttle valve shaft 40b and rotates integrally with the throttle valve shaft 40b.

The throttle valve 40c is rotatable counterclockwise in FIG. 1 in the valve opening direction by the driver's operation or the like. It is biased clockwise in the valve closing direction so as to be positioned at the fully closed position in contact with the inner wall surface.

In the internal combustion engine 10 as described above, the intake structure S is configured to give a tumble swirl flow of the fuel-air mixture in the combustion chamber 20 in order to obtain more favorable combustion in the combustion chamber 20, i.e., vertical rotation. ing. That is, the intake passage 38 is divided along the direction of intake air flow by a partition portion 62 leading from the inlet pipe 36 to the intake port 32, and is configured such that the passing intake air generates a tumble flow within the combustion chamber 20. It is partitioned into a tumble passage 64 and a main passage 66 excluding the tumble passage 64. - 特許庁The tumble passage 64 corresponds to the first intake passage, and the main passage 66 corresponds to the second intake passage. Note that the tumble passage 64 may also be referred to as a secondary passage.

Furthermore, a partition portion 72 is provided in the tumble passage 64 so as to continue from the inlet pipe 36 to the intake port 32 . By providing the partition portion 72, the tumble passage 64 is partitioned into two

intake passages

68 and 70. As shown in FIG. One of the two

intake passages

68 , 70 is the first tumble passage 68 and the other of them is the second tumble passage 70 . The first tumble passage 68 corresponds to the third intake passage, and the second tumble passage 70 corresponds to the fourth intake passage.

The partition 62 that separates the tumble passage 64 and the main passage 66 is called the main partition, and the partition 72 that separates the first tumble passage 68 and the second tumble passage 70 of the tumble passage 64 is called the sub-partition. The main partition 62 extends like a plate in the direction of flow of intake air, and the sub-partition 72 also extends like a plate along the direction of the flow of intake air, for example, substantially parallel to the main partition 62 . The main partition 62 is provided so as to substantially bisect the intake passage 38 in the vertical direction, here so as to extend substantially along the central axis extending in the flow direction, and the cross-sectional area of the tumble passage 64 is It is not much different from the channel cross-sectional area of the main passage 66 . However, the main partition 62 may be provided such that the cross-sectional area of the tumble passage 64 is smaller than the cross-sectional area of the main passage 66, and this relationship can be reversed. Further, the sub-partition 72 is provided so as to substantially bisect the tumble passage 64 in the vertical direction, here, so as to extend substantially along the central axis of the tumble passage 64 extending in the flow direction. It may be provided so as to be biased in either direction.

The lower portion of the intake passage 38 partitioned by the main partition 62 is the tumble passage 64, the upper portion is the main passage 66, and the lower portion partitioned by the secondary partition 72 of the tumble passage 64 is the first tumble passage 68. The upper portion provides the secondary tumble passages 70, although they are not limited to their vertical arrangement herein. In this specification, the terms "top" and "bottom" of the intake passage 38 and the like refer to the direction from the crankshaft 17 to the cylinder head 14 or the cylinder head cover 24 in the direction of the cylinder axis C. , the direction opposite to this "upward" direction, that is, the direction from the cylinder head 14 side to the crankshaft 17 side is called the "downward" or "downward" direction, and the absolute "upward" or "downward" direction in space. does not mean The "up" or "up" direction corresponds to the first direction, and the "down" or "down" direction corresponds to the second direction.

A tumble valve body 76 is connected to the upstream end of the inlet pipe 36 via an insulator 74 . The tumble valve body 76 has an intake passage 76a with a substantially circular cross section forming part of the intake passage 38, and the throttle body 40 is connected to the upstream end thereof.

The tumble valve body 76 is rotatably supported in the tumble valve body 76 by a valve shaft 76b that intersects the central axis of the intake passage 76a perpendicularly to the flow direction of intake air in the intake passage 76a. A tumble valve 76c that can variably control the flow area of the air intake passage 76a and open and close the upper region of the air intake passage 76a in cooperation with the

partitions

62, 72 is provided. The tumble valve 76c is of the butterfly type, and has a valve shaft 76b and a substantially disk-shaped valve body 76d that is fixed to the valve shaft 76b and rotates together. In this manner, the tumble valve 76c is configured with the valve element 76d, which is a single valve member that rotates integrally with the valve shaft 76b. The tumble valve 76c may also be called a tumble control valve, TCV, or the like, and corresponds to the intake control valve of the present invention.

　Here, Figs. 2 and 3 show a three-dimensional model M1 of the portion of the intake passage 38 on the downstream side of the throttle valve 40c. 2 is a perspective view of the three-dimensional model M1 from the downstream side, and FIG. 3 is a view of the three-dimensional model M1 from the horizontal direction (perpendicular to the vertical direction). FIG. 3 is a view of the three-dimensional model M1 viewed from a direction perpendicular to the valve axis 46c of the intake valve 46 and perpendicular to the extending direction of the main partition 62. As shown in FIG. The three-dimensional model M1 represents the valve body 76d of the tumble valve 76c. 4 shows the valve body 76d of the tumble valve 76c. The valve body 76d, which is the single valve member of the tumble valve 76c, is substantially disk-shaped as described above, but the distal end portion 76t swung around the valve shaft 76b on the downstream side is substantially linear. As a result, the valve body 76d can be in a closed state with respect to the main partitioning portion 62 or can be in a closed state with respect to the sub-partitioning portion 72. As shown in FIG.

The main partition 62 continuously extends from a position immediately downstream of the tumble valve 76c to the intake port 32. Similarly, the sub-partition 72 continuously extends to the intake port 32 from a position immediately downstream of the tumble valve 76c. 1, the valve stem 76b of the tumble valve 76c is positioned above the main compartment 62, and the tumble valve 76c is a butterfly valve, so that the upstream edge of the main compartment 62 62a is located downstream of the upstream edge 72a of the sub-partition 72. As shown in FIG. Note that the downstream edge 62b of the main partition 62 is located downstream of the downstream edge 72b of the sub-partition 72. As shown in FIG.

As shown in FIG. 1, the tumble valve body 76 is provided with a recess 77 that allows movement of the valve element 76d of the tumble valve 76c. The concave portion 77 is provided in an upper wall portion 76u of a wall portion 76e of a tumble valve body 76, which is a wall portion defining and forming the intake passage 38. As shown in FIG.

The tumble valve 76c configured as described above is configured to be able to open and close the main passage 66, which is the second intake passage, and the second tumble passage 70, which is the fourth intake passage. Here, the tumble valve 76c is provided so as not to affect the degree of opening of the first tumble passage 68. It is also possible to be provided in

In FIG. 1, the valve body 76d of the tumble valve 76c is positioned so as to be able to extend in the flow direction, and is in the fully open position PA as indicated by the solid line. In addition to the fully open position PA, the tumble valve 76c has a first position P1 (one-dot chain line in FIG. and a second position P2 extending to the upstream edge 62a of the main partition 62 (a two-dot chain line in FIG. 1). With the tumble valve 76c at the fully open position PA, the tumble passage 64 and the main passage 66 are fully opened. With the tumble valve 76c in the first position P1, the main passageway 66 and the second tumble passageway 70 are substantially closed, leaving the first tumble passageway 68 open. With the tumble valve 76c in the second position P2, the main passageway 66 is substantially closed, leaving the second tumble passageway 70 in addition to the first tumble passageway 68 open. In this way, the tumble valve 76c is used at a plurality of degrees of opening. can be closed such that there is substantially no gap between the Note that the tumble valve 76c can be positioned at any other position. These positions of the tumble valve 76c are controlled by an ECU 80 described later based on the operating state of the internal combustion engine 10 here.

A fuel injection valve 78 is provided in the internal combustion engine 10 . The fuel injection valve 78 is provided downstream of the throttle valve 40c and the tumble valve 76c. A fuel injection valve 78 is provided to inject fuel toward the intake valve 46 via the main passage 66 . The fuel injection amount and the injection timing from the fuel injection valve 78 are controlled in association with the control of each of the throttle valve 40c and the tumble valve 76c. Note that the throttle valve 40c is not limited to being electronically controlled, and may be a valve mechanically controlled by a throttle cable, for example, and the same applies to the tumble valve 76c.

An ECU (electronic control unit) 80 that controls the internal combustion engine 10 has a configuration as a so-called computer, and includes an intake control section 82 and a fuel injection control section 84 . That is, the ECU 80 includes a processing unit or processor, for example a CPU, and a storage device or memory including, for example, ROM and RAM. The ECU 80 analyzes the operating state of the internal combustion engine 10 based on outputs from various sensors such as an engine rotation speed sensor and an engine load sensor, and controls the respective operations of the throttle valve 40c and the tumble valve 76c through the intake control unit 82. do. For example, the throttle valve 40c is controlled to an opening degree according to the operating state of the internal combustion engine 10. For example, when the operating state of the internal combustion engine 10 is in the low load region, the operating state of the internal combustion engine 10 is in the high load region. At some point, the tumble valve 76c is controlled to have a larger opening degree, and similarly, the tumble valve 76c is controlled to an opening degree according to the operating state of the internal combustion engine 10. For example, the operating state of the internal combustion engine 10 is in the low load region. When the operating state of the internal combustion engine 10 is in the high-load region, the opening is controlled to be larger than when it is at . Further, the ECU 80 controls the operation of the fuel injection valve 78 by means of the fuel injection control section 84 based on the analyzed operating state of the internal combustion engine 10 . The ECU 80 stores programs and various data for these controls.

Here, the control of the tumble valve 76c will be explained in detail. For example, when the operating state of the internal combustion engine 10 is in the low load region, the ECU 80 controls the operation of the tumble valve 76c so that it is positioned at the first position P1 so that the intake air is drawn only from the first tumble passage 68. do. As a result, the amount of intake air suitable for the low load region is ensured, and the intake air from the first tumble passage 68 forms a tumble flow in the combustion chamber 20 . Since the first tumble passage 68 has a relatively small cross-sectional area, it is possible to increase the flow velocity even with an intake air amount suitable for a low load region, and to form a strong tumble flow. Here, when the operating state of the internal combustion engine 10 is in the low load region, the fuel injection from the fuel injection valve 78 is controlled so that the air-fuel ratio becomes lean, but by forming the tumble flow, effective combustion is achieved. can be generated.

Further, for example, when the operating state of the internal combustion engine 10 is in the medium load range, the ECU 80 first turns the tumble valve 76c so that the intake air is taken in from the first tumble passage 68 and the second tumble passage 70, that is, from the tumble passage 64. 2 Control its operation so that it is located at position P2. As a result, the amount of intake air suitable for the medium load range is ensured, and the intake air from the first and

second tumble passages

68 and 70 forms a tumble flow in the combustion chamber 20 . Since a tumble flow is formed by intake air from the first and

second tumble passages

68 and 70, strong tumble can be achieved while securing the necessary amount of intake air even in the medium load range where a larger amount of intake air is required than in the low load range. flow can be formed. Here, when the operating state of the internal combustion engine 10 is in the medium load range, the fuel injection from the fuel injection valve 78 is controlled so that the air-fuel ratio becomes lean, but by forming the tumble flow, effective combustion is achieved. can be generated.

Furthermore, for example, when the operating state of the internal combustion engine 10 is in the high load region, the ECU 80 controls the tumble passage so that the intake air is taken in from the tumble passage 64 including the first tumble passage 68 and the second tumble passage 70 and the main passage 66. It controls the operation of the valve 76c so that it is in the fully open position PA. As a result, the amount of intake air suitable for the high load region is ensured, and the intake air from the first and

second tumble passages

68 and 70 preferably creates a tumble flow in the combustion chamber 20, and even if not, a suitable cylinder flow is obtained. Realize flow velocity. Here, when the operating state of the internal combustion engine 10 is in the high load region, the fuel injection from the fuel injection valve 78 is controlled so that the air-fuel ratio becomes stoichiometric, and furthermore, by realizing a suitable flow velocity in the cylinder, the effect is further improved. combustion can occur.

For example, when the operating state of the internal combustion engine 10 is in the high load region, the operation of the tumble valve 76c is controlled so that it is positioned at the fully open position PA, and intake air is taken in from the tumble passage 64 and the main passage 66. At this time, the intake structure S of the internal combustion engine 10 is further modified so that the amount of intake air is increased by the intake air from the main passage 66 and the tumble performance by the intake air from the tumble passage 64 can be secured more favorably. It has a different configuration and shape. Further explanation is given below.

A confluence portion 86 is formed on the downstream side of the tumble passage 64 . A confluence portion 86 is provided at a location where the first tumble passage 68 and the second tumble passage 70 merge on the downstream side thereof. The tumble passage 64 merges with the main passage 66 via the junction 86 . The confluence portion 86 is formed in the cylinder head 14 . Here, the confluence portion 86 is formed as part of the intake port 32 .

Here, FIGS. 5 and 6 show a three-dimensional model M2 including the portion of the intake passage 38 on the downstream side of the throttle valve 40c and the tumble valve 76c and the exhaust passage of the exhaust port 34. FIG. FIG. 5 is a view of the three-dimensional model M2 from above, and FIG. 6 is a view of the three-dimensional model M2 from a direction orthogonal to the cylinder axis C and the direction of intake air flow. 7A shows a cross-sectional view of the solid model M2 along the line VIIA-VIIA in FIG. 6, and FIG. 7B shows a cross-sectional view of the solid model M2 along the line VIIB-VIIB in FIG. 7C shows a cross-sectional view of the solid model M2 at a position along the VIIC-VIIC line in FIG. 6, and FIG. 7D shows a cross-sectional view of the solid model M2 at a position along the VIID-VIID line in FIG. show. Line VIIA-VIIA in FIG. 6 passes near the upstream edge of the main partition 62, line VIIB-VIIB in FIG. 6 passes near the downstream edge 72b of the main partition 62, and the line VIID--VIID in FIG. All of these lines VIIA-VIIA to VIID-VIID are parallel to the cylinder axis C in FIG. Note that the exhaust side is omitted in FIGS. 7A to 7D.

7A, 7B and 7C, the first tumble passage 68 and the second tumble passage 70 have generally the same shape and size. Thus, each of the first tumble passage 68 and the second tumble passage 70 smoothly extends from the upstream side to the downstream side without significantly changing its shape or size in the intake air flow direction. The first tumble passage 68 and the second tumble passage 70 are connected to the confluence portion 86 . The confluence portion 86 is connected to the main passage 66 on the downstream side of the downstream edge 62b of the downstream end of the main partition portion 62 (see FIGS. 1 and 6). With this configuration, the first tumble passage 68 and the second tumble passage 70 are connected to the main passage 66 via the confluence portion 86 on the downstream side of the downstream edge 72b of the sub-partition portion 72. As shown in FIG. Therefore, the intake air passing through the first tumble passage 68 and the second tumble passage 70 of the tumble passage 64 can have strong directivity.

In FIG. 6, the line L1 defined to extend in the flow direction at the confluence portion 86 intersects the cylinder axis C at an angle θ1 close to a right angle, whereas the line L1 is defined to extend in the flow direction at the downstream end of the main passage 66. A line L2 intersects the cylinder axis C at an angle .theta.2 smaller than the angle .theta.1. In this manner, the confluence portion 86 is defined so that the intake air from the tumble passage 64 via the confluence portion 86 flows into the combustion chamber 20 at a smaller entrance angle than the intake air from the main passage 66 . With this configuration, the intake air passing through the tumble passage 64 can be introduced into the combustion chamber 20 while maintaining strong directivity, and a strong tumble flow can be generated in the combustion chamber 20, for example. The term "advance angle" as used herein refers to the angle at which the intake air flowing into the combustion chamber 20 flows into the combustion chamber 20. For example, when viewed from a direction perpendicular to the cylinder axis C and the direction of intake air flow, as shown in FIG. , the larger the angle formed with the cylinder axis C, the smaller the approach angle. Here, the approach angle θ is larger than 0° and smaller than 90° (0°<θ<90°).

1, 3 and 6, the tumble passage 64 is defined to have a downwardly convex curved shape, and the main passage 66 is defined to have an upwardly convex curved shape. It is partitioned into With this configuration, as described above, the intake air from the tumble passage 64 can be guided into the combustion chamber at a smaller entrance angle, and the intake air from the main passage 66 can be more effectively guided to the combustion chamber 20. becomes possible.

FIG. 7C shows that the first tumble passage 68 and the second tumble passage 70 communicate with the upstream end of the junction 86 . Here, for reference, FIG. 7C shows a cross section 68A of the first tumble passage 68, a cross section 70A of the second tumble passage 70, and a virtual plane defined at the upstream end 86u of the confluence portion 86, that is, this virtual plane. shows one side TA1 of the cross section at . The side TA1 of the upstream end 86u of the merging portion 86 is clearer than the vertical length of the cross section 68A of the first tumble passage 68 and the vertical length of the cross section 70A of the second tumble passage 70. to long. Thus, the cross-sectional area of each of the first tumble passage 68 and the second tumble passage 70 (areas S1 and S2 in FIG. 7C) is equal to the cross-sectional area S3 of the upstream end 86u of the merging portion 86 (partially by side TA1). (S1<S3, S2<S3). With this configuration, the intake air from the first tumble passage 68 and the intake air from the second tumble passage 70 can preferably flow into the confluence portion 86 . More specifically, when the tumble valve 76c is at the second position P2 and intake air flows through the first tumble passage 68 and the second tumble passage 70, the cross-sectional area of the confluence portion 86 is Since the cross-sectional area is larger than that of each of the passages 70, the amount of intake air is less likely to be restricted at the junction 86, and an amount of intake air suitable for the operating range of the medium load range can be ensured.

Also, for example, side TA2 in FIG. 7D is shorter than side TA1 in FIG. 7C. In other words, the cross-sectional area of the confluence portion 86 of the tumble passage 64 tends to be smaller at the cross-sectional area in FIG. 7D than at the side TA1 in FIG. 7C, for example, toward the downstream side. Thus, in the internal combustion engine 10, the confluence portion 86 is sectioned so as to generally taper from the upstream end portion of the confluence portion 86 toward the downstream side. With this configuration, it is greater than the sum of the cross-sectional areas of the first tumble passage 68 and the second tumble passage 70 (for example, the sum of the area S1 of the cross section 68A and the area S2 of the cross section 70A) and the upstream end portion 86u of the confluence portion 86. The area (cross-sectional area) of the cross section perpendicular to the flow direction on the downstream side becomes smaller. As a result, when the intake air from the first tumble passage 68 and the intake air from the second tumble passage 70 join at the junction 86 and flow into the main passage 66, the flow velocity of the intake air can be kept high. Therefore, the intake air from the tumble passage 64 can flow into the combustion chamber 20 at a high flow velocity and preferably form a tumble flow. The cross-sectional area of the merging portion 86 on the downstream side of the upstream end of the merging portion 86 perpendicular to the flow direction is smaller than the sum of the cross-sectional areas of the first tumble passage 68 and the second tumble passage 70. The taper may be achieved by means other than taper.

The intake structure S of the internal combustion engine 10 described above includes a main partition 62 that separates the tumble passage 64 and the main passage 66, and a sub-partition 72 that separates the tumble passage 64 into first and

second tumble passages

68 and 70. , and a junction 86 where the first and

second tumble passages

68, 70 meet. The tumble passage 64 merges with the main passage 66 via the confluence portion 86 configured as described above.

According to this intake structure S, the main passage 66 and the tumble passage 64 are provided, and the tumble passage 64 can be divided into the first tumble passage 68 and the second tumble passage 70 . Therefore, it is possible to use one or two or all of them depending on the operating state of the internal combustion engine to secure the intake air amount according to the operating state.

Further, according to the intake structure S, since the confluence portion 86 is provided, the intake air from the tumble passage 64 having the first tumble passage 68 and the second tumble passage 70 can have strong directivity. Therefore, tumble performance can be ensured.

Therefore, according to the intake structure S of the internal combustion engine 10, it is possible to ensure both the amount of intake air according to the operating state and the tumble performance.

The number of sub-partitions is not limited to one, and may be plural. By providing a plurality of sub-partitions in the tumble passage 64, the tumble passage 64 is divided into three sections including a third intake passage corresponding to the first tumble passage 68 and a fourth intake passage corresponding to the second tumble passage 70. It is possible to divide the intake passage into the above intake passage, that is, the intake passage portion. The plurality of divided intake passage portions should preferably be connected to the main passage 66 via the confluence portion 86 and then to the combustion chamber 20 in the same manner as the first and

second tumble passages

68 and 70 described above. In this case, the plurality of sub-partitions may be provided in the tumble passage 64 separately in the vertical direction.

It should be noted that the tumble valve 76c is not limited to having a single valve member, that is, a valve body. Also, a plurality of valves may be combined and applied so as to realize the above function of the tumble valve 76c.

Also, various members that define the intake passage of the internal combustion engine 10, particularly the intake passage on the downstream side of the throttle valve 40c, are preferably manufactured mainly by casting. As a result, various shapes such as a downwardly convex tumble passage 64 and an upwardly convex main passage 66 can be realized. It should be noted that the present disclosure does not exclude the production of the member that defines the intake passage by a method other than casting.

Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to them. Various substitutions and changes can be made without departing from the spirit and scope of the invention as defined by the claims of this application.

For example, the internal combustion engine 10 is a single-cylinder engine and has one intake valve 46 and one exhaust valve 50 for one cylinder. However, the number of cylinders of the internal combustion engine, the number of intake valves per cylinder, and/or the number of exhaust valves per cylinder can be arbitrarily determined within a range consistent with the above technology.

10... internal combustion engine, 12... cylinder block, 14... cylinder head, 15... piston,
20... combustion chamber, 28... intake valve port,
30...Exhaust valve port, 32...Intake port, 34...Exhaust port, 38...Intake passage 40...Throttle body, 46...Intake valve,
50 ... Exhaust valve,
62... Partition (main partition), 64... Tumble passage (first intake passage), 66... Main passage (second intake passage), 68... First tumble passage,
70...second tumble passage, 72...partition (secondary partition), 76...tumble valve body, 76c...tumble valve (intake control valve),
86 ... confluence,
S: Intake structure.

Claims

When defining the first direction from the crankshaft (17) side to the cylinder head (14) side in the direction of the cylinder axis (C), the intake passage (38) communicating with the combustion chamber (20) of the internal combustion engine (10) is designated as the first direction. a main partition (62) that separates a first intake passage (64) from a second intake passage (66) on the first direction side of the first intake passage (64);
A secondary partition provided in the first intake passage (64) to form a third intake passage (68) and a fourth intake passage (70) on the first direction side of the third intake passage (68). a part (72);
A confluence portion (86) where the third intake passageway (68) and the fourth intake passageway (70) merge, and the first intake passageway (64) is connected to the first intake passageway (64) via the confluence portion (86). 2. An intake structure (S) for an internal combustion engine (10), comprising a junction (86) that merges with two intake passages (66).
2. The intake of the internal combustion engine (10) according to claim 1, wherein the junction (86) is connected to the second intake passage (66) downstream of the downstream end of the main partition (62). Structure (S).
The intake air from the first intake passage (64) through the junction (86) flows into the combustion chamber (20) at a smaller entrance angle than the intake air from the second intake passage (66). 3. An intake structure (S) for an internal combustion engine (10) according to claim 2, wherein said merging portion (86) is partitioned.
The cross-sectional areas (S1, S2) of each of the third intake passage (68) and the fourth intake passage (70) are greater than the cross-sectional area (S3) of the upstream end (86u) of the junction (86). 4. An intake structure (S) for an internal combustion engine (10) according to any one of claims 1 to 3, characterized in that the confluence (86) is formed so as to be small.
Flow downstream of the upstream end (86u) of the junction (86) relative to the sum of the cross-sectional areas (S1, S2) of the third intake passage (68) and the fourth intake passage (70) 5. The merging portion (86) is partitioned so that the cross-sectional area of the merging portion (86) in a cross section orthogonal to the direction is small. An intake structure (S) for the described internal combustion engine (10).
When the direction opposite to the first direction in the direction of the cylinder axis (C) is defined as the second direction,
The first intake passage (64) is sectioned to have a curved shape convex in the second direction,
The internal combustion engine (10) according to any one of claims 1 to 5, wherein the second intake passage (66) is sectioned to have a curved shape convex in the first direction. ) intake structure (S).
Further comprising an intake control valve (76c) provided upstream of the main partition (62),
The intake control valve (76c) is configured to be able to open and close the second intake passage (66) and the fourth intake passage (70). A first position (P1) that closes the intake passage (70), a second position (P2) that closes the second intake passage (66) and opens the fourth intake passage (70), and a fully open position (PA). An intake structure (S) for an internal combustion engine (10) according to any one of claims 1 to 6, characterized in that it comprises:
The intake control valve (76c) includes a single valve member (76d) that rotates integrally with the valve shaft (76b),
A concave portion (77) for allowing movement of the valve member (76d) is provided in a wall portion (76u) on the first direction side of walls defining the intake passageway (38). 8. The intake structure (S) for an internal combustion engine according to claim 7.
A plurality of sub-partitions (72) are provided,
The first intake passage (64) is divided into three or more intake passages including the third intake passage (68) and the fourth intake passage (70) by a plurality of sub-partitions (72). An intake structure (S) for an internal combustion engine according to any one of claims 1 to 8, characterized in that: