JP2007231916A - Intake device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure high filling efficiency without generating swirl. <P>SOLUTION: An intake device has a pair of intake ports 4, 5 having shapes symmetrical with each other with respect to a flat surface including a cylinder axis. An upper wall face 14 of an intake air inlet passage part 8 of each of the intake ports 4, 5 is constituted of a first upper wall face 14a and a second upper wall face 14b lower than the first upper wall face 14a, and a lower-laminar flow passage X and an upper-laminar flow passage Y are formed so that a height position of the second upper wall face 14b is a border between the passages X, Y. The lower-laminar flow flowing in the lower-laminar flow passage X flows in a peripheral direction of a combustion chamber 3 through an intake valve opening part area Z when an intake valve 6 is opened. The upper-laminar flow flowing in the upper-laminar flow passage Y flows into the combustion chamber 3 through a swirl part 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intake device for an internal combustion engine.

  A first portion is formed by a spiral portion formed around the axis of the intake valve and an intake air inflow passage portion extending tangentially from the spiral portion, and the intake air inflow passage portion is tangentially connected to the peripheral wall surface of the spiral portion. And a second side wall surface extending to the circumferential wall surface of the spiral portion toward the valve shaft of the intake valve, the upper wall surface of the intake air inflow passage portion is the first side wall surface described above. A first upper wall surface located on the side and smoothly connected to the upper wall surface of the spiral portion, and a second upper wall surface located on the second side wall surface side and having a height lower than that of the first upper wall surface A lower flow that flows along the bottom wall surface of the intake air inflow passage portion and an upper flow that flows along the first upper wall surface at the height position of the second upper wall surface. A helical intake port is known in which swirl is generated in the combustion chamber by the flow. (See Patent Document 1).

In this helical type intake port, when the intake air amount is large, the swirling action of the upper layer flow in the spiral portion is weakened by the lower layer flow, thereby preventing the occurrence of excessive swirl in the high engine speed region.
Japanese Utility Model Publication No. 2-147830

  By the way, in this helical type intake port, swirl is generated in the combustion chamber by swirling the intake air in the spiral portion as in the conventional helical type intake port. In this case, in order to strengthen the swirl, the swirling action in the spiral portion must be strengthened. However, if the swirling action in the spiral portion is increased, the suction resistance increases, so that the charging efficiency is lowered, and as a result, the output during the maximum load operation is lowered.

As long as the swirl is strengthened by strengthening the swirling action in the spiral part, it is difficult to ensure a strong swirl and high filling efficiency at the same time. To ensure a strong swirl and high filling efficiency at the same time Needs a change of mindset.
The inventor has studied the flow of intake air over a long period of time, and finally found an intake port that can simultaneously ensure a strong swirl and high filling efficiency.

  A first object of the present invention is to provide an intake device that can obtain a high filling efficiency without generating a swirl by using a powerful swirl and an intake port that can ensure a high filling efficiency at the same time. The purpose is to provide an intake device that can control the strength of the swirl using an intake port that can simultaneously ensure a strong swirl and high filling efficiency, and that can obtain high filling efficiency without generating a swirl if necessary. It is to provide.

  In order to achieve the first object, according to a first aspect of the present invention, there is provided an intake device for an internal combustion engine including a pair of intake ports having a symmetrical shape with respect to a plane of symmetry including a cylinder axis. And the intake air inflow passage portion extending tangentially from the spiral portion, the peripheral wall surface extending around the axis of the intake valve, the upper wall surface, and the intake valve A first side wall surface in which the intake air inflow passage portion is tangentially connected to the peripheral wall surface of the spiral portion, and the spiral portion toward the valve shaft of the intake valve. The second side wall surface extending to the peripheral wall surface, the upper wall surface, and the bottom wall surface are demarcated. The lower end outlet of the spiral portion is disposed at the peripheral edge of the combustion chamber top surface, and the first side wall surface is It extends tangentially to the periphery of the combustion chamber The intake air inflow passage portion is disposed between the cylinder axis and the center portion of the intake valve valve body in the annular intake valve opening formed between the intake valve and the valve seat of the intake valve when the intake valve is fully opened. An intake valve opening region formed on the opposite side to the intake air inflow passage portion with respect to the reference plane including the lower plane flow and the intake air inflow passage flowing below the intake air inflow passage portion in the intake air inflow passage portion An upper layer flow that flows above the upper part is generated, and the lower layer flow flows toward the intake valve opening region when the intake valve is opened and then flows into the combustion chamber from the intake valve opening region toward the periphery of the combustion chamber. The flow swirls in the spiral portion when the intake valve is opened, and then is dispersed from the entire intake valve opening and flows into the combustion chamber.

  In order to achieve the second object, in the first invention described above, a flow control valve is disposed in the intake air inflow passage portion of one intake port of the pair of intake ports. Is fully open, the strength of the lower flow that flows from the intake valve opening region of one intake port toward the periphery of the combustion chamber, and the intake valve opening region of the other intake port toward the periphery of the combustion chamber When the inflow of the lower flow is the same, no swirl is generated in the combustion chamber, and when the flow control valve is closed, the intake valve opening region of one intake port is directed toward the periphery of the combustion chamber. Compared to the inflowing lower layer flow, the lower layer flow that flows in from the intake valve opening region of the other intake port toward the periphery of the combustion chamber becomes stronger, so that a swirl is generated in the combustion chamber.

  As each intake port, swirl is generated by the lower layer flow flowing in the lower layer flow path, and high intake efficiency is ensured by the upper layer flow flowing in the upper layer flow path, so that it is high without generating swirl Filling efficiency can be ensured, and swirl can be controlled while ensuring high filling efficiency.

  1 to 3, reference numeral 1 denotes a cylinder block, 2 denotes a cylinder head, 3 denotes a combustion chamber, and a pair of intake ports 4 and 5 are formed in the cylinder head 2. As shown in FIG. 1, these intake ports 4 and 5 have a symmetrical shape with respect to a symmetry plane K1 including the cylinder axis. Therefore, hereinafter, only the shape of the intake port 4 will be described, and description regarding the shape of the intake port 5 will be omitted.

  Referring to FIGS. 1 to 3, the intake port 4 is constituted by a spiral portion 7 formed around the axis of the intake valve 6 and an intake air inflow passage portion 8 extending tangentially from the spiral portion 7. As shown in FIGS. 1, 2, and 3 (C), the spiral portion 7 includes a peripheral wall surface 9 that extends around the axis of the intake valve 6, an upper wall surface 10, and a lower end outlet portion 11 that is opened and closed by the intake valve 6. 1 and 2, the intake air inflow passage portion 8 includes a first side wall surface 12 tangentially connected to the peripheral wall surface 9 of the spiral portion 7, and a valve of the intake valve 6. It is demarcated by the 2nd side wall surface 13 extended to the surrounding wall surface 9 of the spiral part 7 toward the axis | shaft 6a, the upper wall surface 14, and the bottom wall surface 15. FIG.

  As can be seen from FIG. 1, the lower end outlet portion 11 of the spiral portion 7 is disposed at the peripheral portion of the top surface 16 (FIG. 2) of the combustion chamber 3, and the first side wall surface 12 is tangent to the peripheral portion of the combustion chamber 3. An intake air inflow passage portion 8 is arranged so as to extend in a shape. That is, as shown in FIG. 1, the downstream side of the intake air inflow passage portion 8 extends tangentially to the peripheral edge of the combustion chamber 3, and the upstream side of the intake air inflow passage portion 8 is for layout reasons. It is slightly bent in the direction away from the combustion chamber 3 with respect to the downstream side of the intake air inflow passage portion 8.

  FIG. 5 is a perspective view schematically showing the intake port 4. In FIG. 5, the intake port 5 is indicated by a one-dot chain line for easy understanding of the shape of the intake port 4. Referring to FIGS. 1 to 3 and FIG. 5, the upper wall surface 14 of the intake air inflow passage portion 8 is located on the first side wall surface 12 side at least downstream of the intake air inflow passage portion 8 and A first upper wall surface 14a that smoothly connects to the upper wall surface 10 and a second upper wall surface 14b that is located on the second side wall surface 13 side and located on the bottom wall surface 15 side with respect to the first upper wall surface 14a. Composed. The cross-sectional shape of the intake air inflow passage portion 8 where the second upper wall surface 14b is formed at a lower position than the first upper wall surface 14a is shown by hatching in FIG.

  As can be seen from FIGS. 3A to 3C and FIG. 5, the first upper wall surface 14a descends gradually toward the spiral portion 7 while the lateral width gradually decreases, and then the upper wall surface of the spiral portion 7 as described above. 10 is connected smoothly. The upper wall surface 10 of this spiral part 7 extends over almost ¾ of the entire circumference of the spiral part 7 while gradually descending along the peripheral part of the spiral part 7. On the other hand, the width of the second upper wall surface 14 b is approximately 1/3 of the width of the bottom wall surface 15 on the downstream side of the intake air inflow passage portion 8 and is constant, and on the upstream side of the intake air inflow passage portion 8. It gradually becomes ugly as you go to.

  On the other hand, as shown in FIGS. 3A to 3C and FIG. 5, the first upper wall surface 14 a and the second upper wall surface 14 b extend in a substantially horizontal direction within the cross section of the intake air inflow passage portion 8. The wall surface 17 located between the first upper wall surface 14a and the second upper wall surface 14b is a downward inclined surface. The width of the inclined surface 17 gradually increases toward the spiral portion 7. On the other hand, as shown in FIG. 2, the second upper wall surface 14b is also lowered toward the spiral portion 7. In this case, the inclination angle of the second upper wall surface 14b is larger than the inclination angle of the first upper wall surface 14a. large.

  When the first upper wall surface 14a and the second upper wall surface 14b are formed stepwise in this way, the lower portion of the first side wall surface 12 is shown in the intake air inflow passage portion 8 as indicated by hatching X in FIG. A lower channel defined by the second side wall surface 13, the second upper wall surface 14b, and the bottom wall surface 15, and a lower channel and the first upper wall surface above the lower channel as indicated by hatching Y. The upper flow path located between 14a is formed. That is, in the intake air inflow passage portion 8, two flows are generated: a lower layer flow flowing in the lower layer flow path X and an upper layer flow flowing in the upper layer flow path Y. FIG. 6A shows a case where only a portion related to the lower layer flow path X of FIG. 5 is taken out, and FIG. 6B shows a case where only a portion related to the upper layer flow path Y of FIG. 5 is taken out.

  FIG. 4 shows an enlarged view of FIG. When the intake valve 6 is opened as shown in FIGS. 2 and 3C, an annular intake valve opening 19 is formed between the intake valve 6 and the valve seat 18 of the intake valve 6. In this case, in the annular intake valve opening 19 formed between the intake valve 6 and the valve seat 18 of the intake valve 6 when the intake valve 6 is fully opened, the cylinder axis O and the center of the valve body of the intake valve 6 in FIG. There is an intake valve opening region formed on the opposite side of the intake air inflow passage portion 8 with respect to the reference plane K2 including the portion.

This intake valve opening region is indicated by Z in FIGS. 4, 5 and 6A.
This intake valve opening region Z is a range M of approximately 90 degrees in the swirling direction of the intake air flow in the spiral portion 7 from the intersection of the reference plane K2 and the intake valve opening 19 on the peripheral edge side of the combustion chamber 3 in FIG. It is. In the present invention, as can be seen from FIG. 5 and FIG. 6A, the lower portion of the first side wall surface 12, the second side wall surface 13, the second upper wall surface 14b and the bottom wall surface 15 are provided by the lower flow path X. It is configured to extend straight toward the opening region Z.

  Thus, the second upper wall surface 10 is opposite to the second upper wall surface 10 with respect to the reference plane K2, as shown in FIG. 2, so that the lower layer flow path X extends straight toward the intake valve opening region Z. It extends toward the upper edge of the intake valve opening 19 located. When the lower layer flow path X is formed in this way, the lower layer flow flowing in the lower layer flow path X advances straight in the lower layer flow path X when the intake valve 6 is opened, and then as shown by the arrow S1 in FIG. It flows from the valve opening region Z into the combustion chamber 3 toward the periphery of the combustion chamber 3. Similarly, as for the intake port 5, the lower flow flowing in the lower flow path X of the intake port 5 travels straight through the lower flow path X when the intake valve 6 is opened, as indicated by an arrow S <b> 2 in FIG. 4. It flows from the intake valve opening region Z into the combustion chamber 3 toward the periphery of the combustion chamber 3.

  On the other hand, the upper layer flow flowing in the upper layer flow path Y advances in the upper layer flow path Y when the intake valve 6 is opened, and then swirls in the spiral portion 7 to open the intake valve opening as shown by an arrow T1 in FIG. Dispersed from the entire portion 19 and flows into the combustion chamber 3. Further, the upper layer flow flowing in the upper layer flow path Y of the intake port 5 also advances in the upper layer flow path Y when the intake valve 6 is opened, and then swirls in the spiral portion 7, as indicated by an arrow T2 in FIG. Then, it is dispersed from the whole intake valve opening 19 and flows into the combustion chamber 3. Thus, the amount of intake air can be increased by allowing the intake air to flow from the entire intake valve opening 19. That is, if the upper layer flow is caused to flow into the combustion chamber 3 without swirling, most of the upper layer flow flows into the combustion chamber 3 only from the intake valve opening on the side opposite to the intake air inflow passage portion 8. Become. This is substantially the same as the flow passage area of the intake valve opening being reduced, and therefore an increase in the intake air amount cannot be expected.

  On the other hand, when a swirl flow is given to the upper layer flow in the spiral portion 7, the upper layer flow is dispersed from the entire intake valve opening 19 and flows into the combustion chamber 3 as described above. This is the same as the flow passage area of the intake valve opening 19 is increased, and therefore the intake air amount is increased, so that the charging efficiency is improved. In this way, in the present invention, the swirl flow is generated in the spiral portion 7 for the purpose of improving the filling efficiency and not for the generation of swirl as in the prior art.

  On the other hand, when the intake air is swirled in the spiral portion 7 and flows into the combustion chamber 3, it seems as if the swirled intake air flow is shifted to the swirl flow as it is. However, it is a part of the swirling intake air flow that is directed toward the periphery of the combustion chamber 3 that contributes to the generation of swirl. Therefore, even if the intake air is swirled and flows into the combustion chamber 3 Actually, only a part of the intake air contributes to the generation of the swirl. That is, in order to generate a swirl, it is most effective to generate a strong intake air flow toward the periphery of the combustion chamber 3 as indicated by S1 and S2 in FIG.

  Now, in the example shown in FIG. 4, the pair of intake air flows S1 and S2 collide with each other at the periphery of the combustion chamber 3 on the side opposite to the intake valve 6, that is, on the exhaust valve 20 side. Since the strength of S2 is the same, no swirl is generated by these intake air flows S1 and S2. Further, as described above, the intake air flow that contributes to the generation of swirl out of the intake air flow that flows in from the spiral portion 7, that is, the intake air flow toward the periphery of the combustion chamber 3 collides with each other. Will not generate a swirl. Therefore, the swirl is not generated in the example shown in FIG.

  On the other hand, since the lower layer flow path X extends straight toward the intake valve opening region Z as described above, the lower layer flow flows into the combustion chamber 3 with inertia. Thus, when the intake air flow is supplied into the combustion chamber 3 with inertia, a high charging efficiency can be obtained by a so-called inertia supercharging effect.

  7 and 8 show another embodiment. In this embodiment, a flow control valve 21 is disposed at the inlet of the intake air inflow passage 8 of one of the pair of intake ports 4 and 5. In this embodiment, when the flow rate control valve 21 is fully opened, it is the same as the embodiment shown in FIGS. 1 to 6 and is directed from the intake valve opening region Z of one intake port 4 toward the periphery of the combustion chamber 3. Since the strength of the inflowing lower flow and the strength of the lower flow flowing in from the intake valve opening region Z of the other intake port 5 toward the periphery of the combustion chamber are the same, swirl is generated in the combustion chamber 3 do not do.

  On the other hand, when the flow control valve 21 is closed, the intake valve of the other intake port 5 is compared with the lower flow that flows from the intake valve opening region Z of one intake port 4 toward the periphery of the combustion chamber 3. Since the lower layer flow flowing from the opening region Z toward the periphery of the combustion chamber 3 becomes stronger, a swirl is generated in the combustion chamber 3.

  In addition, when the flow control valve 21 is fully closed, intake air is supplied into the combustion chamber 3 only from the intake port 5. At this time, a strong swirl is generated in the combustion chamber 3 by the lower flow that flows straight from the intake port 4 into the combustion chamber 3 toward the periphery of the combustion chamber 3, and the combustion is performed after swirling in the spiral portion 7. The amount of intake air is increased by the upper layer flow flowing into the chamber 3. Thus, even at this time, a strong swirl is generated while achieving high filling efficiency.

  9 and 10 show an embodiment in which the charging efficiency is improved when the flow rate control valve 21 is closed in FIG. 7 and FIG. That is, in this embodiment, as shown in FIGS. 9 and 10, the flow control valve 22 is disposed in the lower layer flow path X in which the lower layer flow flows in order to control the flow rate of the lower layer flow.

  In FIG. 4, the strength of the intake air flow indicated by S <b> 1 is governed by the flow rate of the lower flow flowing in the lower flow channel X of the intake port 4, so that the lower flow rate control valve 22 causes the lower flow rate as shown in FIGS. 9 and 10. By controlling the flow rate of the flow, the strength of the swirl can be controlled. Further, in this embodiment, since the upper layer flow that contributes to the filling efficiency is constantly flowing, the filling efficiency is increased.

  Next, the case where the present invention is applied to an internal combustion engine having at least four or more even-numbered cylinders arranged in series will be described. FIG. 11 shows an in-line four-cylinder internal combustion engine 30 in which each cylinder has a pair of intake ports 4 and 5 shown in FIGS. 7 and 8 as an example. In FIG. 11, 31 is an intake manifold, 32 is an intake air inlet portion located at the center of the intake manifold 31, 33 is an exhaust manifold, and 34 is exhaust gas discharged into the exhaust manifold 33 in the intake air inlet portion 32. The exhaust gas recirculation (hereinafter referred to as EGR) passages 35 for recirculation are respectively indicated by EGR control valves. The first to fourth cylinders are indicated by # 1 to # 4.

  In the example shown in FIG. 11, each cylinder includes a right-turn swirl generating intake port 4 and a left-turn swirl generating intake port 5. As described above, the intake ports 4 and 5 are symmetrical but have the same shape. Therefore, either intake port 4 or 5 is the same to generate a swirl. That is, from the viewpoint of swirl generation, the flow rate control valve 21 is the same regardless of which intake port 4 or 5 is disposed. Therefore, which intake port 4 or 5 the flow control valve 21 is arranged in can be determined advantageously from another viewpoint.

  In the example shown in FIG. 11, the arrangement of the flow control valve 21 is determined from the viewpoint of making the intake gas amount supplied into each cylinder uniform when the flow control valve 21 is closed. That is, in the example shown in FIG. 11, the intake gas is distributed and supplied into the intake ports 4 and 5 from the intake air inlet 32 located at the center of the intake manifold 31. In this case, for example, when focusing on the first cylinder # 1 and the second cylinder # 2, when any one of the intake ports 4 and 5 is closed by the flow control valve 21, the inside of the adjacent intake ports 4 and 5 among all combinations When intake gas is allowed to flow, that is, when intake gas is allowed to flow through the intake port 4 of the first cylinder # 1 and the intake port 5 of the second cylinder # 2, the cylinders # 1 and # 2 The amount of inhaled gas flowing in is uniform.

  On the other hand, the same can be said when focusing on the third cylinder # 3 and the fourth cylinder # 4. That is, when any one of the intake ports 4 and 5 is closed by the flow control valve 21, when the intake gas is allowed to flow through the adjacent intake ports 4 and 5 among all combinations, that is, the third cylinder # 3 When the intake gas flows through the intake port 4 and the intake port 5 of the fourth cylinder # 4, the amount of intake gas flowing into each cylinder # 3, # 4 becomes uniform. Further, at this time, the EGR gas supplied from the EGR passage 34 into the intake air inlet 32 is also uniformly distributed to the cylinders # 1, # 2, # 3, and # 4.

  Generally speaking, the arrangement of the flow rate control valve 21 can be expressed by swirling direction of swirl generated in the cylinder # 2 located on the center side and the cylinder # 1 located on the end side between the adjacent cylinders # 1 and # 2. The flow rate control valve 21 is disposed in each of the intake ports 4 and 5 that are different from each other, and is generated between the adjacent cylinders # 3 and # 4 in the cylinder # 3 located on the center side and in the cylinder # 4 located on the end side. This means that the flow control valves 21 are arranged in the intake ports 5 and 4 having different swirling directions.

It is a top view of an intake port. It is sectional drawing of the intake port seen along the II-II line of FIG. FIG. 2 is a cross-sectional view of the intake port shown in FIG. 1, wherein (A), (B), and (C) are cross-sectional views taken along lines AA, BB, and CC, respectively, in FIG. It is. It is an enlarged view of FIG. It is a perspective view of the intake port represented graphically. It is a figure which shows the lower layer flow path X and the upper layer flow path Y. It is a top view which shows another Example of an intake port. FIG. 8 is a cross-sectional view of the intake port of FIG. 7 showing a cross section at the same position as in FIG. 2. It is a top view which shows another Example of an intake port. FIG. 10 is a cross-sectional view of the intake port of FIG. 9 showing a cross-section at the same position as FIG. 2. It is a top view of an internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Combustion chamber 4,5 Intake port 6 Intake valve 7 Spiral part 8 Intake air inflow passage part 9 Peripheral wall surface 10 Upper wall surface 11 Lower end outlet part 12 1st side wall surface 13 2nd side wall surface 14a 1st upper wall surface 14b 1st 2 Upper wall surface 15 Bottom wall surface 18 Valve seat 19 Intake valve opening 20 Exhaust valve 21, 22 Flow control valve X Upper layer flow path Y Lower flow path Z Intake valve opening area

Claims (8)

  In an intake device of an internal combustion engine having a pair of intake ports having a symmetrical shape with respect to a symmetry plane including a cylinder axis, each intake port is formed with a spiral portion formed around the axis of the intake valve, and a tangent line from the spiral portion An intake air inflow passage portion extending in a shape, and the spiral portion is defined by a peripheral wall surface extending around the axis of the intake valve, an upper wall surface, and a lower end outlet portion opened and closed by the intake valve, A first side wall surface in which the intake air inflow passage portion is tangentially connected to the peripheral wall surface of the spiral portion; a second side wall surface extending to the peripheral wall surface of the spiral portion toward the valve shaft of the intake valve; and an upper wall surface And a bottom wall surface, the lower end outlet of the spiral portion is disposed at the peripheral edge of the combustion chamber top surface, and the first side wall surface is tangential to the peripheral edge of the combustion chamber. An intake air inflow passage is arranged to extend Of the annular intake valve opening formed between the intake valve and the valve seat of the intake valve when the intake valve is fully opened, the intake air inflow passage portion with respect to a reference plane including the cylinder axis and the central portion of the intake valve valve body There is an intake valve opening region formed on the opposite side, and a lower flow that flows below the intake air inflow passage and an upper flow that flows above the intake air inflow passage are generated in the intake air inflow passage. The lower flow flows toward the intake valve opening region when the intake valve is opened, and then flows from the intake valve opening region into the combustion chamber toward the periphery of the combustion chamber. An intake device for an internal combustion engine that is dispersed from the entire intake valve opening and flows into the combustion chamber after turning in the spiral portion.   A first upper wall surface that is located on the first side wall surface side at least downstream of the intake air inflow passage portion and smoothly connected to the upper wall surface of the spiral portion; And a second upper wall surface positioned on the second side wall surface side and positioned on the bottom wall surface side with respect to the first upper wall surface, and the lower layer flow path through which the lower layer flow flows is the first side The upper layer flow path defined by the lower portion of the wall surface, the upper air second side wall surface, the second upper wall surface, and the bottom wall surface and through which the upper layer flow flows is above the lower layer flow path and the lower flow path and the above The lower channel is formed between the first upper wall surface, the lower portion of the first side wall surface, the second side wall surface, the second upper wall surface, and the bottom wall surface in the intake valve opening region. The intake device for an internal combustion engine according to claim 1, wherein the intake device is configured to extend straight toward the vehicle.   3. The intake device for an internal combustion engine according to claim 2, wherein the second upper wall surface extends toward an upper end edge of an intake valve opening located on the opposite side of the second upper wall surface with respect to the reference plane.   2. The internal combustion engine according to claim 1, wherein the intake valve opening region is in a range of approximately 90 degrees in the swirling direction of the intake air flow in the swirl portion from the intersection of the reference plane and the intake valve opening on the peripheral side of the combustion chamber. Engine intake system.   A flow rate control valve is disposed in the intake air inflow passage portion of one intake port of the pair of intake ports. When the flow rate control valve is fully open, combustion occurs from the intake valve opening region of one intake port. Since the strength of the lower flow flowing toward the periphery of the chamber is the same as the strength of the lower flow flowing from the intake valve opening region of the other intake port toward the periphery of the combustion chamber, swirl is generated in the combustion chamber. When the flow rate control valve is closed without being generated, the intake valve opening of the other intake port is compared with the lower flow that flows from the intake valve opening region of one intake port toward the periphery of the combustion chamber. 2. The intake device for an internal combustion engine according to claim 1, wherein a swirl is generated in the combustion chamber because the lower flow flowing in from the region toward the periphery of the combustion chamber becomes stronger.   6. The intake device for an internal combustion engine according to claim 5, wherein the flow rate control valve is disposed in a lower flow path through which the lower flow flows in order to control a flow rate of the lower flow.   The internal combustion engine has at least four or more even-numbered cylinders arranged in series, and each cylinder has the pair of intake ports each including a right-turn swirl intake port and a left-turn swirl intake port. When a common intake manifold is provided for the pair of intake ports of each cylinder, and intake gas is distributed and supplied from the central portion of the intake manifold into each intake port, and the flow control valve is closed. In order to ensure that the amount of intake gas supplied into each cylinder is uniform, between the adjacent cylinders, the cylinders located on the center side and the cylinders located on the end side have different flow rates in the intake ports with different swirl turning directions. 6. The intake device for an internal combustion engine according to claim 5, wherein a control valve is arranged.   8. The internal combustion engine according to claim 7, wherein a flow control valve is disposed in a central intake port in a cylinder located between the adjacent cylinders in a central side, and in an end intake port in a cylinder located in an end side. Engine intake system.

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