JP7403708B2 - Internal combustion engine intake structure - Google Patents

Description

The present invention relates to an intake structure for an internal combustion engine that is provided with a partition that divides an intake passage into a plurality of sections.

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

Furthermore, in the internal combustion engine disclosed in Patent Document 2, an intake control valve is provided on the downstream side of the throttle valve, and a horizontal plate-like member is further provided in the intake passage on the downstream side of the valve, and extends along the flow direction of intake air. ing. Internal combustion engines are disclosed in which the number of horizontal plate-like members is one and two or more. According to the description in Patent Document 2, by forming a plurality of horizontal plate-like members and determining the opening degree of the intake control valve according to the operating conditions of the internal combustion engine, the intake air can be controlled even at intermediate opening degrees of the intake control valve. Generates stable gas flow without disturbing the flow.

Japanese Patent No. 6714764 Japanese Patent Application Publication No. 2006-77590

By the way, in order to properly operate an internal combustion engine, it is necessary to ensure an amount of intake air according to the operating state of the internal combustion engine, and to appropriately generate a vortex flow such as a tumble flow in the combustion chamber to increase combustion efficiency. It is desirable to be able to balance this with other things. However, for example, the configuration of Patent Document 2 is mainly aimed at realizing an intake air amount depending on the operating state, and has a problem in maintaining tumble performance even when the engine load changes, for example. An object of the present invention is to provide an internal combustion engine in which an intake passage is divided by a partition part, which makes it possible to both secure an amount of intake air depending on the operating condition and ensure tumble performance. It is in.

In order to achieve the above object, one aspect of the present invention is to
When a first direction is defined as a direction from the crankshaft side to the cylinder head side in the direction of the cylinder axis, an intake passage connected to the combustion chamber of the internal combustion engine is defined as a first intake passage; a main partition section that partitions into two intake passages;
a sub-partition portion provided in the first intake passage to form a third intake passage and a fourth intake passage on the first direction side of the third intake passage;
a merging portion where the third intake passage and the fourth intake passage merge, the first intake passage merging with the second intake passage via the merging portion; The present invention provides an intake structure for an internal combustion engine with characteristics.

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 which can become tumble passages, and the second intake passage, depending on the operating state of the internal combustion engine. By using any or all of them, it is possible to ensure an intake flow rate depending on the operating state. Further, according to the above configuration, since the merging section is provided, the intake from the first intake passage including the third intake passage and the fourth intake passage can be given strong directivity, and tumble performance is ensured. can do. Therefore, according to the above-mentioned intake structure for an internal combustion engine, in an internal combustion engine configured such that the intake passage is divided by a partition part, it is possible to achieve both ensuring an intake air amount according to the operating state and ensuring tumble performance. becomes possible.

Preferably, the merging section connects to the second intake passage on a downstream side of a downstream end of the main partition section. With this configuration, the intake air passing through the first intake passage can be given strong directivity.

Preferably, the merging portion is formed into sections such that the intake air from the first intake passage via the merging portion flows into the combustion chamber at a smaller angle of approach 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 merging portion is formed into sections such that each of the third intake passage and the fourth intake passage has a smaller cross-sectional area than an upstream end of the merging portion. With this configuration, the intake air from the third intake passage and the intake air from the fourth intake passage suitably flow into the merging portion, thereby making it possible to ensure a sufficient intake air flow rate.

Preferably, the cross-sectional area of the merging portion in a cross section perpendicular to the flow direction downstream 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 merging portion is formed into sections 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 merging portion and flow into the second intake passage, it is possible to maintain the flow rate of the intake air at a high state.

Preferably, when a direction opposite to the first direction in the direction of the cylinder axis is defined as a second direction, the first intake passage is sectioned to have a curved shape convex in the second direction. , the second intake passage is sectioned to have a convex curved shape in the first direction. This configuration makes it possible to guide the intake air from the first intake passage into the combustion chamber at a smaller angle of approach, and also makes it possible to guide the intake air from the second intake passage into the combustion chamber more effectively. .

Preferably, the above-described intake structure for an internal combustion engine 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 is in a first position where the second intake passage and the fourth intake passage are closed; It is preferable to have a second position where 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 suitably generate a tumble flow while ensuring a more suitable amount of intake air depending on the operating state.

Preferably, the intake control valve includes a single valve member that rotates around a valve shaft, and a recess that allows movement of the valve member is located in the first wall portion of the wall defining the intake passage. It is provided on the wall in one direction. With this configuration, the amount of intake air can be more easily adjusted by controlling the movement of a single valve member, and the recessed portion can improve the opening/closing function of the valve member. .

The intake structure for the internal combustion engine described above may include a plurality of the sub-partition parts. 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 the plurality of sub partitions. With this configuration, it becomes possible to more finely adjust the amount of intake air depending on the operating state.

According to the above aspect of the present invention, since the above structure is provided, in an internal combustion engine configured such that the intake passage is divided by a partition part, it is possible to both secure an intake air amount according to the operating state and ensure tumble performance. It becomes possible to suitably achieve this.

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

Embodiments according to the present invention will be described below based on the accompanying drawings. Identical 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.

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

A piston 15 that reciprocates within a cylinder bore 12b of the cylinder block 12 is connected to a crank pin of a crankshaft 17 of a crankcase portion 16 by a connecting rod 18. A combustion chamber 20 is formed between the top surface 15a of the piston 15, which is slidably fitted into the cylinder bore 12b of the cylinder block 12, and the combustion chamber ceiling surface 14a of the cylinder head 14, which the top surface 15a faces. Ru.

The internal combustion engine 10 employs an SOHC type two-valve system, and the cylinder head 14 is provided with a valve mechanism 22. A cylinder head cover 24 is placed over 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. The camshaft 26 is installed between the camshaft 26 and the crankshaft 17 through a cam chain chamber, and the camshaft 26 rotates at 1/2 the rotational speed in synchronization with the crankshaft 17. In the cylinder head 14, a spark plug is inserted into the combustion chamber 20 from the side opposite to the cam chain chamber (the other side in the crankshaft direction).

In the cylinder head 14, an intake port 32 and an exhaust port 34 are formed to curve and extend vertically away from each other from an intake valve port 28 and an exhaust valve port 30 that are open to the combustion chamber ceiling surface 14a. The upstream end of the intake port 32 opens toward the upper side of the cylinder head 14 and is connected to the 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. Ru.

A downstream end of the exhaust port 34 opens toward the bottom of the cylinder head 14 and is connected to an exhaust pipe 42. An exhaust purification device and a muffling device may be provided downstream of the exhaust pipe 42.

A cylindrical intake valve guide 44 is integrally fitted into 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.

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

The intake valve 46 and the exhaust valve 50 are urged upward by valve springs so that their umbrella parts 46a and 50a close the intake valve port 28 and the exhaust valve port 30, both of which face the combustion chamber 20. The stem ends 46b and 50b of the intake valve 46 and exhaust valve 50 are pushed down by the intake rocker arm 56 and exhaust rocker arm 58, which swing in contact with the intake cam and exhaust cam of the camshaft 26, and the intake valve 46 and the exhaust valve 50 are pushed down at a predetermined timing. The exhaust valve 50 opens, and the intake port 32 and the combustion chamber 20 communicate with each other, and the exhaust port 34 and the combustion chamber 20 communicate with each other, so that 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, and 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 having a substantially circular cross section and forming a part of the intake passage 38 connected to 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 within the throttle body 40 by a throttle valve shaft 40b that is perpendicular to the flow direction of intake air in the intake passage 40a, that is, perpendicular to the center axis of the intake passage 40a. The intake passage 40a is provided with a throttle valve 40c that can variably control the flow passage area of the intake passage 40a and open/close the intake passage 40a. The throttle valve 40c is of a butterfly type and includes a throttle valve shaft 40b and a disc-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 can be rotated counterclockwise in FIG. 1 in the valve opening direction by the driver's operation, and a return spring (not shown) causes the valve body 40d to have its edge aligned with the intake passage 40a. The valve is biased clockwise in the valve closing direction so as to be in the fully closed position where it contacts the inner wall surface.

In the internal combustion engine 10 as described above, in order to obtain more preferable combustion in the combustion chamber 20, an intake structure S is configured to provide a tumble vortex flow, that is, a vertical rotation, of the fuel/air mixture in the combustion chamber 20. ing. That is, the intake passage 38 is divided along the intake flow direction by a partition 62 that extends from the inlet pipe 36 to the intake port 32, and the intake passage 38 is configured to generate 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. The tumble passage 64 corresponds to a first intake passage, and the main passage 66 corresponds to a second intake passage. Note that the tumble passage 64 may also be referred to as a sub-passage.

Further, 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 divided into two intake passages 68 and 70. One of the two intake passages 68, 70 is the first tumble passage 68 and the other thereof is the second tumble passage 70. The first tumble passage 68 corresponds to a third intake passage, and the second tumble passage 70 corresponds to a fourth intake passage.

Note that the partition 62 that partitions the tumble passage 64 and the main passage 66 is referred to as a main partition, and the partition 72 that partitions the first tumble passage 68 and the second tumble passage 70 of the tumble passage 64 is referred to as a sub-partition. The main partition part 62 extends in a plate shape in the flow direction of the intake air, and the sub partition part 72 also extends in the flow direction of the intake air in a plate shape along the main partition part 62, for example, substantially parallel to the main partition part 62. The main partition portion 62 is provided so as to substantially bisect the intake passage 38 in the vertical direction, here substantially extending on the central axis extending in the flow direction, and the flow passage cross-sectional area of the tumble passage 64 is It is not significantly different from the 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 it is also possible to reverse this relationship. In addition, the sub-partition part 72 is provided so as to substantially divide the tumble passage 64 into two in the vertical direction, here substantially extending on 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 part of the intake passage 38 partitioned by the main partition part 62 becomes the tumble passage 64, the upper part becomes the main passage 66, and the lower part of the tumble passage 64 partitioned by the sub partition part 72 becomes the first tumble passage 68, The upper portion constitutes the second tumble passage 70, but in this specification they are not limited to that vertical arrangement. In this specification, "upper" and "lower" with respect to the intake passage 38, etc. refer to the direction from the crankshaft 17 side to the cylinder head 14 or cylinder head cover 24 side in the direction of the cylinder axis C. ” direction, and the direction opposite to this “up” direction, that is, the direction from the cylinder head 14 side to the crankshaft 17 side, is called the “down” or “down” direction, and is the absolute “up” and “down” direction in space. ” does not mean. This "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 having a substantially circular cross section and forming a part of the intake passage 38, and the aforementioned throttle body 40 is connected to the upstream end of the intake passage 76a.

The tumble valve body 76 is rotatably supported within the tumble valve body 76 by a valve shaft 76b that is perpendicular to the flow direction of the intake air in the intake passage 76a, that is, perpendicular to the center axis of the intake passage 76a. A tumble valve 76c is provided which can variably control the flow path area of the air intake path 76a and open and close the upper area of the intake path 76a in cooperation with the partitions 62 and 72. The tumble valve 76c is of a butterfly type and includes a valve shaft 76b and a substantially disk-shaped valve body 76d that is fixed to the valve shaft 76b and rotates integrally with the valve shaft 76b. In this way, the tumble valve 76c is configured to include the valve body 76d, which is a single valve member that rotates integrally with the valve shaft 76b. Note that the tumble valve 76c may also be referred to as a tumble control valve, TCV, etc., and corresponds to the intake control valve of the present invention.

Here, a three-dimensional model M1 of the portion of the intake passage 38 on the downstream side of the throttle valve 40c is shown in FIGS. 2 and 3. FIG. 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 left and right direction (orthogonal to the vertical direction). FIG. 3 is a diagram 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 direction in which the main partition 62 extends. The three-dimensional model M1 shows the valve body 76d of the tumble valve 76c. Further, FIG. 4 shows the valve body 76d of the tumble valve 76c. The valve body 76d, which is a single valve member of the tumble valve 76c, is approximately disk-shaped as described above, but the tip portion 76t, which swings around the valve shaft 76b on the downstream side, is approximately straight. Thereby, the valve body 76d can be in a closed state with the main partition part 62 or in a closed state with the sub partition part 72.

The main partition portion 62 continuously extends from a position immediately downstream of the tumble valve 76c to the intake port 32. Similarly, the sub-partition portion 72 extends continuously from a position immediately downstream of the tumble valve 76c to the intake port 32. As is clear from FIG. 1, the valve shaft 76b of the tumble valve 76c is positioned above the main partition part 62, and since the tumble valve 76c is a butterfly type valve, the upstream end of the main partition part 62 62a is located on the downstream side of the upstream edge 72a of the sub-partition part 72. Note that the downstream end edge 62b of the main partition section 62 is located on the downstream side of the downstream end edge 72b of the sub partition section 72.

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

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, but it is provided so as to extend, for example, to a part of the first tumble passage 68 so as to affect the degree of opening of the first tumble passage 68. It is also possible to provide a.

In FIG. 1, the valve body 76d of the tumble valve 76c is positioned so that it can extend in the flow direction, and is in the fully open position PA, as shown by the solid line. In addition to this fully open position PA, the tumble valve 76c has a first position P1 (dotted chain line in FIG. 1) where the downstream side of the valve body 76d extends to the upstream edge 72a of the sub-partition part 72, and a first position P1 (dotted chain line in FIG. 1) where the downstream side of the valve body 76d extends It has a second position P2 (double-dashed line in FIG. 1) extending to the upstream end edge 62a of the main partition part 62. With the tumble valve 76c in the fully open position PA, the tumble passage 64 and the main passage 66 are fully open. With the tumble valve 76c in the first position P1, the main passage 66 and the second tumble passage 70 are substantially closed, with the first tumble passage 68 naturally remaining open. With the tumble valve 76c in the second position P2, the main passage 66 is substantially closed and the second tumble passage 70 in addition to the first tumble passage 68 is open. In this way, the tumble valve 76c is used at a plurality of opening degrees, but since the recess 77 is provided, the wall 76u and the valve body 76d can be used in both the first position P1 and the second position P2. can be closed so that there is virtually no gap between them. Note that the tumble valve 76c can be positioned at any position other than these. These positions of the tumble valve 76c are controlled here by an ECU 80, which will be described later, based on the operating state of the internal combustion engine 10.

The internal combustion engine 10 is provided with a fuel injection valve 78. Fuel injection valve 78 is provided downstream of throttle valve 40c and tumble valve 76c. The fuel injection valve 78 is provided to inject fuel toward the intake valve 46 via the main passage 66. The amount of fuel injected from the fuel injection valve 78 and its injection timing are controlled in association with the respective controls 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 that is mechanically controlled, for example, by a throttle cable, and the same applies to the tumble valve 76c.

An ECU (electronic control unit) 80 that controls the internal combustion engine 10 is configured 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 device, ie, a processor, which is, for example, a CPU, and a storage device, ie, 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 speed sensor and an engine load sensor, and controls each operation of the throttle valve 40c and tumble valve 76c using the intake control unit 82. do. For example, the throttle valve 40c is controlled to an opening degree depending on the operating state of the internal combustion engine 10, such that the operating state of the internal combustion engine 10 is in a high load region more than when the operating state of the internal combustion engine 10 is in a low load region. At some point, the tumble valve 76c is controlled to open more widely, and similarly, the tumble valve 76c is controlled to an opening depending on the operating state of the internal combustion engine 10, for example, when the operating state of the internal combustion engine 10 is in a low load region. When the operating state of the internal combustion engine 10 is in the high load range, the opening degree is controlled to be larger than when the internal combustion engine 10 is in the high load range. Furthermore, the ECU 80 controls the operation of the fuel injection valve 78 using the fuel injection control section 84 based on the analyzed operating state of the internal combustion engine 10. Note that the ECU 80 stores programs and various data for these controls.

Here, 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 a low load region, the ECU 80 controls the operation of the tumble valve 76c to position it at the first position P1 so that intake air is drawn only from the first tumble passage 68. do. This ensures an amount of intake air suitable for the low load region, and forms a tumble flow in the combustion chamber 20 with the intake air from the first tumble passage 68. Since the first tumble passage 68 has a relatively small cross-sectional area, the flow velocity can be increased even with an intake air amount suitable for a low load region, and a strong tumble flow can be formed. Here, when the operating state of the internal combustion engine 10 is in a low load region, fuel injection from the fuel injection valve 78 is controlled so that the air-fuel ratio is lean, but by forming a tumble flow, combustion is effectively performed. can be caused.

Further, for example, when the operating state of the internal combustion engine 10 is in a medium load region, the ECU 80 controls the tumble valve 76c to the first tumble valve 76c so as to draw intake air from the first tumble passage 68 and the second tumble passage 70, that is, from the tumble passage 64. Its operation is controlled so that it is located at the second position P2. This ensures an amount of intake air suitable for the medium load region, and forms a tumble flow in the combustion chamber 20 with the intake air from the first and second tumble passages 68, 70. Since a tumble flow is formed by the intake air from the first and second tumble passages 68 and 70, a strong tumble flow is achieved while ensuring the required amount of intake air even in the medium load region where a larger amount of intake air is required than in the low load region. can form a flow. Here, when the operating state of the internal combustion engine 10 is in a medium load region, fuel injection from the fuel injection valve 78 is controlled so that the air-fuel ratio is lean, but by forming a tumble flow, combustion is effectively performed. can be caused.

Furthermore, for example, when the operating state of the internal combustion engine 10 is in a high load region, the ECU 80 controls the tumble passage so that intake air is drawn from the tumble passage 64 including the first tumble passage 68 and the second tumble passage 70 and the main passage 66. The operation of the valve 76c is controlled so that it is located at the fully open position PA. This ensures an intake air amount suitable for the high load region, and also provides a tumble flow preferably in the combustion chamber 20 with intake air from the first and second tumble passages 68 and 70, and even if not, a suitable cylinder flow. Achieve flow velocity. Here, when the operating state of the internal combustion engine 10 is in a high load region, fuel injection from the fuel injection valve 78 is controlled so that the air-fuel ratio becomes stoichiometric, and by achieving a more suitable in-cylinder flow velocity, it is more effective. can cause combustion.

For example, when the operating state of the internal combustion engine 10 is in a high load region, the operation of the tumble valve 76c is controlled so that it is located at the fully open position PA, and intake air is drawn from the tumble passage 64 and the main passage 66. At this time, the intake structure S of the internal combustion engine 10 is 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 ensured more favorably. It has the following configuration and shape. This will be further explained below.

A merging section 86 is defined on the downstream side of the tumble passage 64. The merging 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 then merges with the main passage 66 via the merging portion 86. The merging portion 86 is formed in the cylinder head 14. Here, the merging portion 86 is formed as a part of the intake port 32.

Here, FIGS. 5 and 6 show a three-dimensional model M2 including a portion of the intake passage 38 on the downstream side of the throttle valve 40c and the tumble valve 76c, and an exhaust passage of the exhaust port 34. FIG. 5 is a view from above of the three-dimensional model M2, and FIG. 6 is a view of the three-dimensional model M2 from a direction perpendicular to the cylinder axis C and perpendicular to the intake flow direction. Furthermore, a cross-sectional view of the three-dimensional model M2 at a position along the VIIA-VIIA line in FIG. 6 is shown in FIG. 7A, and a cross-sectional view of the three-dimensional model M2 at a position along the VIIB-VIIB line in FIG. 6 is shown in FIG. 7B. 7C shows a cross-sectional view of the three-dimensional model M2 along the VIIC-VIIC line in FIG. 6, and FIG. 7D shows a cross-sectional view of the three-dimensional model M2 along the VIID-VIID line in FIG. show. The VIIA-VIIA line in FIG. 6 passes near the upstream edge of the main partition 62, the VIIB-VIIB line in FIG. 6 passes near the upstream end of the intake port 32, and the VIIC-VIIC line in FIG. The line VIID-VIID in FIG. 6 passes near the downstream edge 62b of the main partition 62. These lines VIIA-VIIA to VIID-VIID are all 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. In this way, 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 the shape or size in the intake flow direction. The first tumble passage 68 and the second tumble passage 70 are connected to a confluence section 86. The merging portion 86 connects to the main passage 66 on the downstream side of the downstream edge 62b at 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 part 86 on the downstream side of the downstream edge 72b of the sub-partition part 72. Therefore, the intake air that has passed through the first tumble passage 68 and the second tumble passage 70 of the tumble passage 64 can be given strong directivity.

In FIG. 6, a line L1 that is defined to extend in the flow direction at the confluence section 86 intersects the cylinder axis C at an angle θ1 that is close to a right angle, whereas a line L1 is defined to extend in the flow direction at the downstream end of the main passage 66. Line L2 intersects cylinder axis C at an angle θ2 smaller than angle θ1. In this way, the merging portion 86 is sectioned so that the intake air from the tumble passage 64 via the merging portion 86 flows into the combustion chamber 20 at a smaller angle of approach than the intake air from the main passage 66. With this configuration, the intake air that has passed through the tumble passage 64 can be introduced into the combustion chamber 20 while maintaining strong directivity, and, for example, a strong tumble flow can be generated in the combustion chamber 20. Note that the approach angle here is the angle at which intake air flows into the combustion chamber 20, and for example, as shown in FIG. The larger the angle formed with the cylinder axis C, the smaller the approach angle. Note that here, the approach angle θ is an angle larger than 0° and smaller than 90° (0°<θ<90°).

Furthermore, as is clear from FIGS. 1, 3, and 6, the tumble passage 64 is sectioned to have a downwardly convex curved shape, and the main passageway 66 is formed to have an upwardly convex curved shape. The area is divided into sections. With this configuration, as described above, it is possible to guide the intake air from the tumble passage 64 into the combustion chamber at a smaller angle of approach, and it is also possible to guide the intake air from the main passage 66 into the combustion chamber 20 more effectively. becomes possible.

FIG. 7C shows first tumble passage 68 and second tumble passage 70 communicating with the upstream end of merging section 86. For reference, FIG. 7C shows the cross section 68A of the first tumble passage 68, the cross section 70A of the second tumble passage 70, and the virtual plane defined at the upstream end 86u of the merging section 86, that is, this virtual plane. One side TA1 of the cross section at is shown. The side TA1 of the upstream end 86u of the confluence section 86 is more obvious 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. long. In this way, 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 different from the cross-sectional area S3 of the upstream end 86u of the merging section 86 (partially due to the side TA1). The merging portion 86 is formed into sections such that (S1<S3, S2<S3) is smaller than the area of the cross section where the sections are formed. With this configuration, the intake air from the first tumble passage 68 and the intake air from the second tumble passage 70 can suitably flow into the merging portion 86. More specifically, when the tumble valve 76c is in the second position P2 and the intake air is flowing into the first tumble passage 68 and the second tumble passage 70, the cross-sectional area of the confluence part 86 is Since the cross-sectional area is larger than that of each of the passages 70, the amount of intake air is not easily restricted by the confluence section 86, and it is possible to secure an amount of intake air that is suitable for the operating region of the medium load region.

Further, for example, the side TA2 in FIG. 7D is shorter than the side TA1 in FIG. 7C. That is, the cross-sectional area of the merging portion 86 of the tumble passage 64 tends to become smaller toward the downstream side, for example, at the cross-sectional area in FIG. 7D than at the side TA1 in FIG. 7C. In this manner, in the internal combustion engine 10, the merging portion 86 is formed into sections so as to be generally tapered from the upstream end of the merging portion 86 toward the downstream side. With this configuration, 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) is larger than that of the upstream end 86u of the merging portion 86. The area (cross-sectional area) in a cross section perpendicular to the flow direction on the downstream side becomes smaller. Thereby, when the intake air from the first tumble passage 68 and the intake air from the second tumble passage 70 merge at the merging portion 86 and flow into the main passage 66, it becomes possible to maintain the flow rate of the intake air at a high state. Therefore, the intake air from the tumble passage 64 can flow into the combustion chamber 20 at a high flow rate and preferably form a tumble flow. Note that the cross-sectional area of the confluence section 86 in a cross section perpendicular to the flow direction on the downstream side of the upstream end of the confluence section 86 is made smaller than the sum of the cross-sectional areas of the first tumble passage 68 and the second tumble passage 70. This may be achieved by means other than tapering.

The intake structure S of the internal combustion engine 10 described above includes a main partition part 62 that partitions the tumble passage 64 and the main passage 66, and a sub partition part 72 that partitions the tumble passage 64 into first and second tumble passages 68 and 70. , and a merging section 86 where the first and second tumble passages 68 and 70 merge. The tumble passage 64 then merges with the main passage 66 via the merging portion 86 configured as described above.

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

Further, according to the intake structure S, since the merging section 86 is provided, the intake air from the tumble passage 64 including the first tumble passage 68 and the second tumble passage 70 can be given 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 intake air amount according to the operating state and the tumble performance.

Note that the number of sub-partition parts is not limited to one, and may be plural. By providing a plurality of sub-partition parts in the tumble passage 64, the tumble passage 64 can be divided into three types 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 becomes possible to divide the intake passage into the above-mentioned intake passage parts. The plurality of divided intake passage portions may be connected to the main passage 66 via the merging portion 86 and connected to the combustion chamber 20 similarly to the first and second tumble passages 68 and 70 described above. In this case, the plurality of sub-partition parts may be provided in the tumble passage 64 vertically apart from each other.

Note that the tumble valve 76c is not limited to having a single valve member, that is, a valve body. Furthermore, a plurality of valves may be used in combination to achieve the above-mentioned function of the tumble valve 76c.

Further, the 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. This makes it possible to realize various shapes, such as a tumble passage 64 that is convex on the lower side and a main passage 66 that is convex on the upper side. Note that the present disclosure does not exclude that the member defining the intake passage may be manufactured by a method other than casting.

Although the embodiments and modifications thereof according to the present invention have been described above, the present invention is not limited thereto. 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 includes 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 part (main partition part), 64...Tumble passage (first intake passage), 66...Main passage (second intake passage), 68...First tumble passage,
70...Second tumble passage, 72...Partition part (subpartition part), 76...Tumble valve body, 76c...Tumble valve (intake control valve),
86…merging part,
S...Intake structure.

Claims (11)

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) connected to the combustion chamber (20) of the internal combustion engine (10) is defined as the first direction. a main partition part (62) that partitions into a first intake passage (64) and a second intake passage (66) on the first direction side of the first intake passage (64);
a sub-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); Part (72) and
A merging portion (86) where the third intake passage (68) and the fourth intake passage (70) merge, and the first intake passage (64) connects to the fourth intake passage through the merging portion (86). a merging portion (86) that merges with the second intake passage (66);
The merging part (86) is connected to the second intake passage (66) on the downstream side of the downstream end of the main partition part (62),
The intake air from the first intake passage (64) via the merging portion (86) flows into the combustion chamber (20) at a smaller approach angle than the intake air from the second intake passage (66). An intake structure (S) for an internal combustion engine (10), characterized in that the merging portion (86) is formed into sections. (delete) (delete) (delete) 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) connected to the combustion chamber (20) of the internal combustion engine (10) is defined as the first direction. a main partition part (62) that partitions into a first intake passage (64) and a second intake passage (66) on the first direction side of the first intake passage (64);
a sub-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); Part (72) and
A merging portion (86) where the third intake passage (68) and the fourth intake passage (70) merge, and the first intake passage (64) connects to the fourth intake passage through the merging portion (86). a merging portion (86) that merges with the second intake passage (66);
The flow is more downstream than the upstream end (86u) of the merging section (86) than the sum of the cross-sectional areas (S1, S2) of the third intake passage (68) and the fourth intake passage (70). An intake structure (S) for an internal combustion engine (10), wherein the merging portion (86) is formed into sections such that the cross-sectional area of the merging portion (86) in a cross section perpendicular to the direction is small. . (delete) (delete) 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) connected to the combustion chamber (20) of the internal combustion engine (10) is defined as the first direction. a main partition part (62) that partitions into a first intake passage (64) and a second intake passage (66) on the first direction side of the first intake passage (64);
a sub-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); Part (72) and
A merging portion (86) where the third intake passage (68) and the fourth intake passage (70) merge, and the first intake passage (64) connects to the fourth intake passage through the merging portion (86). a merging portion (86) that merges with the second intake passage (66);
an intake control valve (76c) provided upstream of the main partition part (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) in which the intake passage (70) is closed, a second position (P2) in which the second intake passage (66) is closed and the fourth intake passage (70) is opened, and a fully open position (PA). have,
The intake control valve (76c) includes a single valve member (76d) that rotates integrally with the valve shaft (76b),
A recessed portion (77) for allowing movement of the valve member (76d) is provided in the wall portion (76u) on the first direction side among the wall portions defining the intake passageway (38). Intake structure (S) of an internal combustion engine. A plurality of the sub-partition parts (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 the plurality of sub partitions (72). The intake structure (S) for an internal combustion engine according to any one of claims 1, 5 and 8, characterized in that: The cross-sectional area (S1, S2) of each of the third intake passage (68) and the fourth intake passage (70) is larger than the cross-sectional area (S3) of the upstream end (86u) of the merging portion (86). Intake structure (S) for an internal combustion engine (10) according to any one of claims 1, 5, 8 and 9, characterized in that the merging portion (86) is sectioned to be small. When defining a direction opposite to the first direction in the direction of the cylinder axis (C) as a second direction,
The first intake passage (64) is sectioned to have a convex curved shape in the second direction,
According to any one of claims 1, 5, 8, 9, and 10, wherein the second intake passage (66) is sectioned to have a convex curved shape in the first direction. Intake structure (S) of the internal combustion engine (10) described.

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