JP2005061368A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine provided with an intake port, in which strength of tumble currents can be kept high in a combustion chamber, and in which intake flow at the intake port can be increased. <P>SOLUTION: This internal combustion engine 1 comprises the intake port 4 composed of a cylinder center side intake port range 4a as a center side range of a cylinder 2 in the internal combustion engine 1, and a cylinder outer circumferential side intake port range 4b as the other range. It also comprises an intake port enlarged part 8 in which the port radius of the intake port 4 on the side of the cylinder outer circumferential side intake port range 4b is increased from the upstream side of the intake port 4 toward right upstream of a combustion chamber opening part 7, and an intake regulating part 9 on the downstream side of the intake port enlarged part 8 toward the combustion chamber opening part 7 in which the port radius on the cylinder outer circumferential side intake port range 4b is decreased to introduce part of flow of intake toward the center of the intake port. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine having an intake port.

  In order to improve the combustion of the fuel in the internal combustion engine, it is necessary to promote the mixing of the fuel and the intake air in the combustion chamber and to secure an appropriate intake amount into the combustion chamber. In order to promote mixing of fuel and intake air in the combustion chamber, a means for forming a swirl flow in the combustion chamber is known, and one of the swirl flows is a vertical swirl flow (hereinafter referred to as “tumble flow”). "). As the strength of the tumble flow increases, the fuel and intake air are more agitated in the combustion chamber, and as a result, mixing of the fuel and intake air is promoted.

  Here, the strength of the tumble flow formed in the combustion chamber is determined by the state of the intake air flowing into the combustion chamber from the intake port. In order to increase the tumble flow, there is known a technique to reduce (reduce) the cross-sectional area of the intake port in order to increase the flow velocity of the intake air flowing into the combustion chamber through the intake port. In this case, the flow rate of the intake air decreases. However, there is a possibility that the maximum output of the internal combustion engine may be reduced or the combustion may become unstable due to insufficient intake air amount. Therefore, in order to suppress a decrease in the intake flow rate, the intake port cross-sectional shape is made asymmetric and the center of the intake air flow in the intake port is decentered with respect to the center of the intake valve, so that A technique for increasing the flow velocity of intake air and thereby maintaining the strength of the tumble flow and avoiding the reduction of the intake air flow rate is disclosed (for example, see Patent Document 1).

Further, in order to reduce the flow resistance of the intake air flowing into the combustion chamber from the intake port, the intersection of the center of the intake port and the center of the intake valve is located near the seating surface of the valve seat of the intake valve or downstream of the seating surface. The technique of making it position is disclosed (for example, refer patent document 2). Thus, the flow resistance is reduced by forming the intake port as straight as possible, thereby maintaining the strength of the tumble flow and avoiding the reduction of the intake flow rate.
Japanese Utility Model Publication No. 4-137224 JP-A-8-277746 JP-A-7-150945

  Here, the strength of the tumble flow is greatly influenced by the flow velocity of the intake air flowing into the combustion chamber from the intake port. However, when the flow velocity of the intake air is increased by reducing the cross-sectional area of the intake port, the flow velocity of the intake air increases. However, there is a risk that the flow rate of the intake air will decrease, and the engine output and combustion stability of the internal combustion engine may be impaired.

  In view of the above problems, an object of the present invention is to provide an internal combustion engine that includes an intake port that maintains a high tumble flow strength in a combustion chamber and increases the flow rate of intake air in the intake port.

In order to solve the above-described problems, the present invention focuses on the port radius of the intake port and the direction of the flow of intake air in the vicinity of a portion where the intake port is connected to the combustion chamber (hereinafter referred to as “combustion chamber opening”). . This is because the flow rate of the intake air varies depending on the radius of the intake port, and the strength of the tumble flow formed in the combustion chamber varies depending on the state of the intake air flowing into the combustion chamber from a specific portion.

  Therefore, the present invention is an internal combustion engine including an intake port, wherein the intake port is a cylinder center side intake port region that is a region on the center side of the cylinder of the internal combustion engine, and the intake port. It is comprised from the cylinder outer peripheral side intake port area | region which is another area | region. The cylinder outer peripheral intake port region has a port radius on the cylinder outer peripheral intake port region side in the vicinity of the combustion chamber opening of the intake port so that the port radius from the upstream side of the intake port directly to the combustion chamber opening. The port radius on the cylinder outer periphery side intake port region side decreases between the intake port widened portion that increases as it progresses to the upstream portion and the downstream side of the intake port widened portion and reaches the combustion chamber opening. And an intake air adjusting section for guiding a part of the intake air flow toward the center of the intake port.

  Mainly, the direction in which the intake air flows into the combustion chamber from the combustion chamber opening of the intake port is a direction toward the center of the cylinder (hereinafter referred to as “forward rotation direction”) and a direction away from the center (hereinafter referred to as “reverse rotation”). The intake air flowing into the combustion chamber from each direction forms a tumble flow in the combustion chamber. Here, the center of the cylinder refers to the center in the longitudinal direction of the cylinder. The direction toward the center of the cylinder refers to the direction toward the inside of the cylinder, and the direction away from the center of the cylinder refers to the direction toward the inner wall surface of the cylinder.

  Therefore, when the intake air flows in the forward rotation direction, the intake air flows to the side where the exhaust port is provided through the center of the cylinder, passes through a relatively wide space in the combustion chamber, and flows in a tumble flow in the forward rotation direction (hereinafter, “ This is referred to as a “positive tumble flow”. On the other hand, when the intake air flows in the reverse rotation direction, the intake air flows toward the inner wall side of the cylinder, passes through a relatively narrow space in the combustion chamber, and forms a tumble flow in the reverse rotation direction (hereinafter referred to as “reverse tumble flow”). Is done. Therefore, in order to promote the mixing of the fuel intake by the tumble flow, it is preferable to form the tumble flow in the forward rotation direction. In addition, the stronger the reverse tumble flow, the more the strength of the normal tumble flow is offset. Therefore, the efficient mixing of fuel intake by the tumble flow becomes more difficult.

  Here, when the intake ports provided in the internal combustion engine are classified into the cylinder center side intake port region on the center side of the cylinder and the cylinder outer periphery side intake port region on the opposite side, the relationship between the intake valve and the intake port In addition, the intake air flowing into the combustion chamber through the cylinder outer peripheral intake port region has a high probability of forming a reverse tumble flow in the combustion chamber, and the intake air flowing into the combustion chamber through the cylinder central intake port region is High probability of forming a positive tumble flow. Therefore, in the internal combustion engine described above, an intake port widening portion and an intake adjustment portion are provided in the cylinder outer peripheral side intake port region.

  In the intake port widened portion, the port radius on the cylinder outer peripheral side intake port region side gradually increases from the upstream side to the portion immediately upstream of the combustion chamber opening of the intake port, so the cross-sectional area of the intake port gradually increases. To increase. As a result, the flow resistance at the intake port is reduced, and the flow rate of intake air can be increased. Further, in the intake adjustment portion, the port radius on the cylinder outer periphery side intake port region side that has increased in the intake port widening portion is reduced, so that the straight movement of the intake air flowing in the cylinder outer periphery side intake port region is prevented, and the center of the intake port Will be changed in direction. As a result, at least a part of the intake air flowing through the cylinder outer peripheral intake port region merges with the intake air flowing through the cylinder central intake port region, and the probability of flowing into the combustion chamber in the forward rotation direction increases.

As a result, the strength of the positive tumble flow that is the tumble flow that promotes the mixing of the fuel and the intake air in the combustion chamber can be maintained high, and the flow rate of the intake air at the intake port can be increased.

  Further, when the cylinder center side intake port region is in the vicinity of the combustion port opening of the intake port, the port radius on the cylinder center side intake port region side is changed from the upstream side of the intake port to the combustion chamber opening. It is preferable to have an intake inlet that increases or remains constant as it goes on.

  Such an intake air introduction portion facilitates the flow of the intake air flowing through the cylinder center side intake port region into the combustion chamber along the shape of the port, thereby promoting the formation of a positive tumble flow. In addition, since the flow direction of the intake air flowing through the cylinder center side intake port region is restrained from being directed toward the center of the intake port, the intake adjustment unit of the cylinder outer periphery side intake port region described above causes the intake port to move toward the center of the intake port. Collision with a part of the introduced intake air is avoided as much as possible, so that formation of a positive tumble flow in the combustion chamber is further promoted.

  Further, in the internal combustion engine described above, an intake valve may be cited as a flow resistance of intake air when intake air flows from the intake port into the combustion chamber. Therefore, the tangential direction of the outline of the intake port in the intake adjustment portion in the cylinder outer peripheral intake port region is made substantially the same as the generatrix direction of the valve body of the intake valve provided in the intake port.

  Here, the tangential direction of the outline of the intake port refers to the direction of intake air whose flow is adjusted along the intake air adjusting portion. In addition, the generatrix direction of the valve body of the intake valve refers to the tangential direction of the cap-shaped portion of the valve body in the cross section of the valve body including the central axis of the valve body. In this way, the intake flow direction guided to the center of the intake port by the adjusting portion of the cylinder outer peripheral intake port and the bus direction of the intake valve are substantially the same, so that the intake valve for intake air It is possible to reduce the resistance caused by. Here, the tangential direction of the outline of the cylinder outer peripheral side intake port in the intake adjustment portion and the bus line direction of the valve body of the intake valve provided in the intake port are substantially the same, the directions of each other are completely the same. In other words, it is the identity within a range where a reduction in flow resistance to intake by the intake valve can be found.

  Here, since the intake valve is provided in the opening of the combustion chamber, the resistance by the intake valve is large with respect to the intake air flowing through the central portion of the intake port. Therefore, even if the intake air flowing through the cylinder outer peripheral intake port region is guided toward the center of the intake port by the intake adjustment unit at the center portion of the intake port, the introduced intake air is blocked by the intake valve and efficiently corrected. It is difficult to contribute to the formation of tumble flow. On the other hand, when the port radius is decreased by the intake air adjusting unit, the flow resistance against the intake air is increased, and the intake air flow rate may be decreased.

  Therefore, the shape of the intake port of the internal combustion engine described above is a part of the intake port including the intake port widened portion, and the cross-sectional shape of the intake port is a square shape or a substantially square shape, and includes the intake adjustment portion. In a part of the intake port, the cross-sectional shape of the intake port is circular or substantially circular.

  In this way, when the intake air proceeds from the intake port widened portion to the intake air adjusting portion, the cross-sectional shape of the intake port is a quadrangular shape at the end of the partial cross section of the intake port including the intake port widened portion. By changing from a square shape (including a substantially quadrangular shape) to a circular shape (substantially circular shape), the geometrically overlapped area is relatively greatly reduced, thereby greatly reducing the port radius of the intake port and increasing the flow of intake air. Blocked. On the other hand, in the central portion of the cylinder outer peripheral side of the cross section of a part of the intake port including the intake port widened portion, the cross section of the intake port changes from a square shape (including a substantially square shape) to a circular shape (a substantially circular shape). ), The geometrically overlapping region does not vary greatly, so the variation in the radius of the intake port is small, and the flow of intake air is not largely blocked.

  As a result, in the central portion of the cross section of the intake port, introduction of the intake air toward the center of the intake port by the intake air adjusting portion of the cylinder outer peripheral side intake port region is eased and the flow resistance of the intake air is reduced. Intake amount is secured. On the other hand, at the end of the cross section of the intake port, intake air is introduced toward the center of the intake port by the intake air adjusting portion in the cylinder outer peripheral intake port region, so that the formation of a positive tumble flow in the combustion chamber is efficient. To be done.

  Here, in an internal combustion engine in which one cylinder is provided with two or more intake ports, the intake ports as shown below are provided in order to ensure both the intake port intake flow rate and the formation of a positive tumble flow in the combustion chamber. Is proposed. That is, an internal combustion engine having a first intake port and a second intake port, wherein the first intake port and the second intake port are the center of the cylinder of the internal combustion engine at each intake port. The cylinder center side intake port region, which is a side region, and the cylinder outer peripheral side intake port region, which is the other region of each intake port.

  The cylinder outer peripheral intake port regions of the first intake port and the second intake port are in the vicinity of the respective combustion chamber openings of the first intake port and the second intake port. The port radii on the cylinder outer periphery side intake port region side between the ports of the first intake port and the second intake port are equal to each other from the upstream side of each intake port to the respective combustion chamber openings. The inter-port side intake port widened portion that increases as it proceeds to the portion immediately upstream, and the downstream side of each inter-port side intake port widened portion to the respective combustion chamber opening portions, respectively. The inter-port intake adjustment unit that guides the intake flow toward the center of each intake port by reducing the port radius of the cylinder outer peripheral intake port region, and the first intake port In the vicinity of the combustion chamber opening of each of the second intake port and the second intake port, the port radius on the cylinder outer peripheral side intake port region side opposite to the inter-port side is the A cylinder outer peripheral side intake air introduction portion that increases or is constant as it advances from the upstream side to each combustion chamber opening.

  That is, in an internal combustion engine having a plurality of intake ports, the cross-sectional shape of the intake port between the ports in the cylinder outer peripheral region of the first intake port and the second intake port among the plurality of intake ports, The cross-sectional shape of the intake port on the side opposite to the inter-port side, that is, on the inner wall surface side of the cylinder is different. When intake air flows into the combustion chamber from the area on the cylinder outer periphery side of the intake port and from the area on the inner wall surface of the cylinder, the intake air flow is likely to come into contact with the inner wall surface of the cylinder, so the flow velocity of the intake air decreases. However, it is difficult to efficiently form a positive tumble flow. On the other hand, if the intake air flows into the combustion chamber from the cylinder outer peripheral region of the intake port and the region between the cylinder ports, contact with the inner wall surface of the cylinder is unlikely to occur, so the decrease in the intake air flow rate is small. .

  In view of this, by providing the cylinder outer periphery side intake introduction portion, the flow rate of the intake air flowing into the combustion chamber from the region on the cylinder outer periphery side of the intake port and from the region on the inner wall surface side of the cylinder is increased as much as possible. Further, by providing the inter-port-side intake port widening portion and the inter-port-side intake adjustment portion, as in the intake port widening portion and the intake adjustment portion described above, it is an area on the cylinder outer periphery side of the intake port and the cylinder port The intake air flowing into the combustion chamber from the intermediate region efficiently contributes to the formation of a positive tumble flow in the combustion chamber. As a result, the strength of the positive tumble flow, which is the tumble flow that promotes the mixing of fuel and intake air in the combustion chamber, can be maintained high, and the intake air flow rate at the intake port can be increased.

Further, in the internal combustion engine described above, the cylinder center side intake port region of each of the first intake port and the second intake port is respectively in a portion in the vicinity of the combustion chamber opening of each intake port. The cylinder center side intake port region has a port radius on the cylinder center side that is increased or constant from the upstream side of each intake port to the respective combustion chamber openings.

  By such a cylinder center side intake introduction portion, the intake air flowing through the cylinder center side intake port region in the first intake port and the second intake port can easily flow into the combustion chamber along the port shape. The formation of a positive tumble flow is promoted. In addition, in each intake port, the flow direction of the intake air flowing through the cylinder center side intake port region is prevented from being directed toward the center direction of the intake port. Collision with a part of the intake air guided toward the center of each intake port is avoided as much as possible, thereby further promoting the formation of a positive tumble flow in the combustion chamber.

  If the internal combustion engine is provided with two intake ports, they may be the first intake port and the second intake port, respectively. Further, in the case where the internal combustion engine is provided with three or more intake ports, the intake ports provided on both end sides, that is, the inner wall surface side of the cylinder, are respectively connected to the first intake port and the intake port. The second intake port may be used. In this case, for the other intake ports located between the first intake port and the second intake port, the cross-sectional area of the intake port is secured in order to secure the intake amount introduced into the combustion chamber as much as possible. It is preferable that the cross-sectional area is gradually increased as the value becomes constant or proceeds downstream.

  In an internal combustion engine having an intake port, the strength of the tumble flow in the combustion chamber can be maintained high and the flow rate of intake air at the intake port can be increased.

  Here, an embodiment of an internal combustion engine according to the present invention will be described based on the drawings.

  FIG. 1A is a diagram (sectional view) showing a schematic configuration in the vicinity of an intake port of an internal combustion engine 1 to which the present invention is applied. FIG. 1B is a diagram in the vicinity of a region A1 in FIG. It is the schematic (sectional drawing) which expanded. The internal combustion engine 1 has a cylinder 2 and the center of the cylinder 2 is represented by a line L1. In the internal combustion engine 1, the intake port 4 is connected to the combustion chamber 3 of the cylinder 2 via the combustion chamber opening 7 on the right side of the line L <b> 1 with respect to FIG. In FIG. 1, the description of the exhaust port, which should originally be in the internal combustion engine 1 (on the left side of the line L1 with respect to FIG. 1A), is omitted. The intake air flows into the combustion chamber 3 through the combustion chamber opening 7 by the opening / closing operation of the intake valve 5. That is, when the intake valve 5 is closed, the valve body 6 of the intake valve 5 comes into contact with the seat portion in the vicinity of the combustion chamber opening 7 to block the intake air from flowing into the combustion chamber. When the intake valve 5 is opened, intake air flows into the combustion chamber 3 through the intake port 4. The flow of the intake air at this time is represented by white arrows D1 and D2 in FIG.

  A white arrow D1 indicates the flow of intake air flowing into the center of the cylinder 2 from the intake port 4, and a normal tumble flow is formed in the combustion chamber 3 by the flow of intake air. A white arrow D2 indicates the flow of intake air flowing from the intake port 4 toward the outer peripheral direction of the combustion chamber 3, that is, toward the inner wall surface of the cylinder 2, and a reverse tumble flow is formed in the combustion chamber 3 by this intake air flow. Is done.

Here, the formation of the tumble flow in the combustion chamber 3 will be described with reference to FIG. The intake port 4 includes a cylinder center side intake port region 4a that is a region on the center line L1 side of the cylinder 2, and a cylinder outer periphery side intake port region 4b that is a region on the opposite side and on the outer periphery side of the cylinder 2. Consists of In the present embodiment, each region is bounded by a plane including the longitudinal center line L2 of the intake port 4, but the configuration of each region is not limited to this mode. Here, in the cylinder center side intake port region 4a, the center line L2 and the cylinder center side intake port region 4a
The port radius of the intake port 4 that is the distance from the inner wall of the intake port is represented by Ra. Further, in the cylinder outer periphery side intake port region 4b, the port radius of the intake port 4 that is the distance between the center line L2 and the intake port inner wall in the cylinder outer periphery side intake port region 4b is represented by Rb.

  Here, in the cylinder center side intake port region 4a in the vicinity of the combustion chamber opening 7, an intake air introduction portion 10 having a constant port radius Ra is formed. Further, in the upstream intake port widened portion 8 of the cylinder outer peripheral intake port region 4 b in the vicinity of the combustion chamber opening 7, the port radius Rb increases as it goes downstream, and immediately upstream of the combustion chamber opening 7. It becomes the maximum value at the part. On the other hand, in the intake air adjusting portion 9 downstream from the portion, the port radius Rb decreases to reach the combustion chamber opening 7. At this time, the tangential direction of the outline of the intake adjustment portion 9 formed by the reduction of the port radius Rb is substantially the same as the generatrix direction of the valve body 6 of the intake valve 5. Therefore, the cross-sectional area of the intake port 4 in the vicinity of the combustion chamber opening 7 is maximized at a portion immediately upstream of the combustion chamber opening 7, and thereafter the cross-sectional area gradually decreases.

  In the intake port 4 configured in this way, the cross-sectional area of the intake port 4 increases as the intake port 4 advances downstream, so that the flow resistance to the intake air 4 decreases, and thus the flow rate of intake air can be increased. Become.

  Further, the intake air flowing through the cylinder center side intake port region 4a flows in the direction of the arrow d1 in the figure along the inner wall surface of the intake port 4 and flows into the combustion chamber 3. On the other hand, the intake air flowing through the cylinder outer peripheral side intake port region 4 b is guided by the intake adjustment unit 9 toward the center line L <b> 2 of the intake port 4. Therefore, a part of the intake air flows in the direction of the arrow d2 in the drawing, and the remaining intake air flows in the direction of the arrow d3 in the drawing and flows into the combustion chamber 3 respectively. Furthermore, since the tangential direction of the outline of the intake adjustment unit 9 is substantially the same as the generatrix direction of the valve body 6 of the intake valve 5, the resistance of the valve body 6 of the intake valve 5 against the flow of intake air flowing in the direction of the arrow d2 is reduced. It becomes possible to suppress as much as possible. Then, the intake air flowing in the directions of the arrows d1 and d2 merge to form the intake air of the flow of the white arrow D1 in FIG. 1A, so that a normal tumble flow is formed in the combustion chamber 3. The The intake air that has flowed in the direction of the arrow d3 forms the intake air of the flow indicated by the hollow arrow D2 in FIG. 1A, so that a reverse tumble flow is formed in the combustion chamber 3.

  FIG. 2 is a diagram schematically showing the appearance of the intake port 4 provided in the internal combustion engine 1. In FIG. 2, two intake ports 4 are provided in parallel, and an intake port widening portion 8 and an intake adjustment portion 9 are formed on the downstream side thereof. In FIG. 2, only one intake port is provided with a reference number.

  Here, FIG. 3 shows an intake port in a conventional internal combustion engine. The difference from the intake port of the internal combustion engine shown in FIGS. 1A and 1B is that the port radius Rc of the intake port 4 is a constant value, and the intake port widening portion 8 shown in FIG. In addition, the intake air adjusting unit 9 is not provided. That is, in the cylinder outer peripheral side region of the intake port 4, the port radius Rc is kept constant and is smoothly connected to the combustion chamber opening 7 via the connection portion 11. Therefore, the intake air flowing through the intake port 4 flows in the direction of the white arrows D1 and D2 in the figure by opening the intake valve 5, and flows into the combustion chamber 3, but the intake adjustment unit 9 shown in FIG. 1 is provided. Therefore, compared to the intake port of the internal combustion engine according to the present embodiment shown in FIG. 1, the flow rate of the intake air flowing in the direction of the white arrow D2 is increased, while the flow rate of the intake air flowing in the direction of the white arrow D1 is Will be reduced.

  That is, in the intake port of the internal combustion engine according to the present embodiment, the amount of intake air in the direction of the white arrow D1 in FIG. 1 that forms a positive tumble flow in the combustion chamber 3 is the direction of the white arrow D1 in FIG. The amount of intake air is further increased, and a stronger positive tumble flow can be formed in the combustion chamber 3.

  In addition, in the intake port of the conventional internal combustion engine, by reducing the port radius at a part thereof and reducing the cross-sectional area of the intake port, the intake port is increased in flow rate by reducing the cross-sectional area of the intake port. A strong tumble flow may be formed. However, in such a case, the resistance to the intake air at the intake port 4 increases, and the flow rate of the intake air flowing into the combustion chamber 3 decreases.

  FIG. 4 shows the relationship between the strength of the positive tumble flow formed in the combustion chamber and the intake flow rate in comparison with the conventional internal combustion engine and the internal combustion engine according to the present embodiment. The horizontal axis of FIG. 4 represents the strength of the positive tumble flow formed in the combustion chamber, for example, the tumble ratio, and the vertical axis represents the flow rate of the intake air flowing into the combustion chamber. In the figure, the line L3 represents the transition of the intake air flow rate with respect to the strength of the positive tumble flow formed in the combustion chamber at the intake port of the conventional internal combustion engine. That is, as described above, the intake flow rate can be increased by making the port radius of the intake port constant, but the strength of the positive tumble flow in the combustion chamber is reduced. On the other hand, it is possible to increase the strength of the positive tumble flow in the combustion chamber by reducing the port radius of the intake port in part and increasing the flow velocity of the intake air, but the intake air flow rate decreases. In other words, the relationship between the strength of the positive tumble flow and the intake flow rate is a contradictory relationship.

  On the other hand, in the internal combustion engine according to the present embodiment, the relationship between the strength of the positive tumble flow formed in the combustion chamber 3 in the intake port 4 of the internal combustion engine 1 and the intake flow rate is represented by a region A2. In other words, the intake port widening portion 8 in FIGS. 1A and 1B reduces the resistance to the intake air in the intake port 4 to increase the intake flow rate, and the intake adjustment portion 9 adjusts the direction of the intake air flow. As a result, the strength of the positive tumble flow formed in the combustion chamber 3 can be increased, and more efficient intake air can be introduced into the conventional internal combustion engine.

  Here, when the port radius of the intake port 4 in the cylinder outer peripheral side intake port region 4b is changed in the intake port widening portion 8 and the intake adjustment portion 9, the sectional shape of the intake port 4 may be as shown in FIG. Good. FIG. 5A is a diagram showing an outline of a partial transverse cross section of the intake port 4, and the intake port 4 is formed by continuously changing the cross-sectional shape thereof. FIG. 5B is a view showing the outline of the intake port shown in FIG. 5A so that the centers of the cross sections overlap.

  In FIG. 5 (a), regions indicated by arrows A3 and A4 are regions corresponding to the intake port widening portion 8 and the intake adjustment portion 9, respectively. S1 and S2 are outlines of the cross section of the intake port 4 in the regions A3 and A4. Therefore, the cross section of the intake port 4 including the intake port widening portion 8 is substantially rectangular, and the cross section of the intake port 4 including the intake adjustment portion 9 is substantially circular, for example, elliptical. 5A and 5B, the upper direction of the drawing corresponds to the center direction of the cylinder 2. Accordingly, the area of the intake port 4 in the upper direction in each figure corresponds to the cylinder center side intake port area 4a described above, and the area of the intake port 4 in the lower direction corresponds to the cylinder intake side area 4b described above.

  Here, as shown in FIG. 5 (b), in the intake port 4 configured in this way, the intake air is adjusted by the intake air adjusting unit 9 in the direction of the center line of the intake port 4 in accordance with the portion of the cross section of the intake port 4. The degree of guidance is different. That is, in the central portion of the cross section of the intake port 4 shown in FIG. 5B, the geometrically overlapping area of the substantially square shape S1 and the substantially circular shape S2 is large. The degree of guiding toward the center is small. Conversely, at the left and right end portions of the cross section of the intake port shown in FIG. 5B, the geometrically overlapping area of the substantially square S1 and the substantially circular S2 is reduced, and the intake air is sucked into the intake port. The degree of guiding toward the center of 4 increases.

As a result, the resistance to the intake by the valve body 6 of the intake valve 5 is increased. In the central portion of the intake port 4, instead of relaxing the degree of guiding the flow of intake air toward the center of the intake port 4,
The intake air flow rate is increased as much as possible to increase the intake air amount flowing into the combustion chamber 3. On the other hand, at the left and right ends of the intake port 4 where the resistance to intake by the valve body 6 of the intake valve 5 is relatively low, the intake flow rate is reduced compared to the central portion, but the direction of intake flow is the intake port. Since the degree of guiding to the center direction of 4 increases, a stronger positive tumble flow is formed in the combustion chamber 3. As a result, it is possible to mitigate the influence of the valve body 6 of the intake valve 5 on the introduction of intake air into the combustion chamber.

  Next, as described above, by increasing the flow rate of the intake air flowing through the cylinder center side intake port region 4a, it becomes possible to form a stronger positive tumble flow in the combustion chamber 3, but as shown in FIG. In the case where the internal combustion engine 1 is provided with two intake ports, even if the intake air flows through the cylinder center side intake port region 4a, a positive tumble flow is formed depending on whether or not it is close to the inner wall surface of the cylinder 2. The degree of contribution to strength is different. Here, FIG. 6 is a diagram showing the top of the cylinder 2, and the same reference numerals are assigned to the same components as those in FIG.

  In FIG. 6, the flow of the intake air flowing into the combustion chamber 3 from the region A <b> 5 that is the cylinder outer peripheral side intake port region 4 b and is expressed by the region on the inner wall surface side of the cylinder 2 is indicated by a black arrow, and the cylinder outer peripheral side intake port The flow of the intake air flowing into the combustion chamber 3 from the region A6 which is the region 4b and is represented by the region between the two intake ports 4 is represented by a white arrow. Here, since the intake air of the flow represented by the black arrow contacts the inner wall surface of the cylinder 2 in a short time, the flow velocity of the intake air decreases, and the degree of contribution to the strength of the normal tumble flow decreases. On the other hand, since the intake air of the flow represented by the white arrow flows toward the center of the cylinder 2, it takes a relatively long time to contact the inner wall surface of the cylinder 2 and the flow velocity of the intake air is unlikely to decrease. High degree of contribution to the strength of the positive tumble flow.

  Therefore, in the direction indicated by the black arrow, the intake port is provided in order to secure the intake air amount flowing into the combustion chamber 3 and in the direction indicated by the white arrow to form a stronger positive tumble flow. By determining the shape, it is possible to achieve both a more efficient formation of a positive tumble flow and securing of the intake air amount.

  Therefore, the shape of the intake port will be described with reference to FIG. FIG. 7A is a diagram showing a schematic external view of the two intake ports 12 and the intake ports 13 and a cross-sectional shape of each portion of the intake ports. The portions of the intake port corresponding to the cross-sectional shape shown in FIG. 7A are a portion in the vicinity of where the intake port 11 and the intake port 12 branch (indicated by a line L6 in the figure), and a portion in the middle of each intake port. (Indicated by the line L7 in the figure) and the portion immediately before the combustion chamber opening of each intake port. Here, in the cross section of each intake port of each part, the upper direction in FIG. 7A is the direction toward the cylinder center described above, and the lower direction in FIG. 7A is the direction toward the cylinder outer periphery described above. It corresponds to.

  Here, FIG. 7B shows the cross-sectional shape S3 of the intake port 12 at the site indicated by the line L7 and the cross-sectional shape S4 of the intake port 12 at the site indicated by the line L8. It is the figure expressed so that may overlap.

  As shown in FIGS. 7A and 7B, in the intake ports 12 and 13, the port radius is substantially constant in the intake port region on the cylinder center side. That is, the intake air introduction portion 10 in FIG. 1 described above is formed.

Further, in the region A7 that is the intake port region on the cylinder outer periphery side and the region between the ports of the intake ports 12 and 13, as the port advances from the part represented by the line L6 to the part represented by the line L7, the port The radius increases. Then, the port radius becomes smaller when proceeding further to the portion represented by the downstream line L8. That is, from the part represented by the line L6 to the part represented by the line L7, the intake port widening portion 8 in FIG. 1 described above is formed, and from the part represented by the line L7 to the part represented by the line L8. Forms the intake air adjusting portion 9 in FIG.

  On the other hand, in the region A8 that is the intake port region on the cylinder outer periphery side and the region on the inner wall surface side of the cylinder 2, the port radius is substantially constant from the part represented by the line L6 to the part represented by the line L8. Or, the variation amount of the port radius is small compared to the region A7.

  In the internal combustion engine having the intake ports 12 and 13 formed in this way, the intake air flowing through the region A7 is indicated by the line L8 from the portion indicated by the line L7, similarly to the intake air flowing through the intake port region on the cylinder center side. The portion corresponding to the above-described intake air adjusting portion formed between the portions to be represented greatly contributes to the formation of the normal tumble flow in the combustion chamber. On the other hand, since the intake air flowing through the region A8 has a relatively small variation in the port diameter of the region, the contribution to the formation of the positive tumble flow in the combustion chamber is relatively small, but a larger intake flow rate can be secured. It becomes possible. Thus, taking into account the decrease in the flow velocity of the intake air due to the inner wall surface of the cylinder, the strength of the tumble flow in the combustion chamber can be maintained higher, and the increase in the intake air flow rate in the intake port can be achieved.

FIG. 1A is a diagram (sectional view) showing a schematic configuration in the vicinity of an intake port of an internal combustion engine according to an embodiment of the present invention, and FIG. 1B is a region A1 in FIG. It is the schematic (sectional drawing) which expanded the vicinity. It is a figure which represents schematically the external appearance of the intake port with which the internal combustion engine which concerns on embodiment of this invention is equipped. It is a figure (sectional view) showing a schematic configuration of an intake port in a conventional internal combustion engine. It is a graph which shows the relationship between the intensity | strength of the positive tumble flow formed in a combustion chamber, and the amount of intake air, comparing the case of the conventional internal combustion engine and the internal combustion engine which concerns on embodiment of this invention. FIG. 5A is a view showing a partial cross-sectional outline of the intake port provided in the internal combustion engine according to the embodiment of the present invention, and FIG. 5B is shown in FIG. It is the figure which represented the outline of the intake port so that the center of a cross section might overlap. It is a figure showing the top part of the cylinder of the internal combustion engine which concerns on embodiment of this invention. FIG. 7A is a schematic external view of two intake ports included in the internal combustion engine according to the embodiment of the present invention, and a diagram showing a cross-sectional shape of each portion of the intake ports. FIG. 7B is a diagram in which the cross-sectional shape of the intake port at the portion indicated by the line L7 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Combustion chamber 4 ... Intake port 4a ... Cylinder center side intake port area 4b ... Cylinder outer peripheral side intake port area 5・ ・ ・ ・ Intake valve 6 ・ ・ ・ ・ Valve 7 ・ ・ ・ ・ Combustion chamber opening 8 ・ ・ ・ ・ Intake port widening part 9 ・ ・ ・ ・ Intake adjustment part

Claims (6)

An internal combustion engine having an intake port,
The intake port is composed of a cylinder center side intake port region which is a region on the center side of the cylinder of the internal combustion engine in the intake port, and a cylinder outer peripheral side intake port region which is another region in the intake port,
The cylinder outer peripheral side intake port region is
In the vicinity of the combustion chamber opening of the intake port, the intake port widening in which the port radius on the cylinder outer peripheral intake port region side increases from the upstream side of the intake port to the portion immediately upstream of the combustion chamber opening. And
In the downstream of the intake port widening portion and to the combustion chamber opening, the port radius on the cylinder outer peripheral intake port region side is reduced so that a part of the intake air flows at the center of the intake port. An internal combustion engine comprising: an intake air adjustment unit that guides in a direction. In the cylinder center side intake port region, the port radius on the cylinder center side intake port region side advances from the upstream side of the intake port to the combustion chamber opening in a portion near the combustion chamber opening of the intake port. The internal combustion engine according to claim 1, further comprising an intake air introduction portion that increases or is constant according to The tangential direction of the outline of the intake port in the intake adjustment section in the cylinder outer peripheral intake port region is substantially the same as the generatrix direction of a valve body of an intake valve provided in the intake port. An internal combustion engine according to claim 1 or claim 2. In a part of the intake port including the intake port widened portion, the cross-sectional shape of the intake port is a square shape or a substantially square shape,
The internal combustion engine according to any one of claims 1 to 3, wherein in a part of the intake port including the intake adjustment portion, a cross-sectional shape of the intake port is a circular shape or a substantially circular shape. . An internal combustion engine having a first intake port and a second intake port,
The first intake port and the second intake port are a cylinder center side intake port region which is a region on the center side of the cylinder of the internal combustion engine in each intake port, and the other intake ports in each intake port. It is composed of a cylinder outer peripheral side intake port region which is a region,
The cylinder outer peripheral side intake port region of each of the first intake port and the second intake port is:
In the vicinity of the respective combustion chamber openings of the first intake port and the second intake port, the respective cylinder outer peripheral side intakes between the ports of the first intake port and the second intake port An inter-port side intake port widening portion in which the port radius on the port region side increases from the upstream side of each intake port to a portion immediately upstream of each combustion chamber opening;
The flow of the intake air is reduced by decreasing the port radius of each of the cylinder outer peripheral side intake port regions between the downstream side of each of the inter-port side intake port widened portions and reaching the respective combustion chamber openings. Intake adjustment part between ports leading to the center direction of each intake port,
In the vicinity of the respective combustion chamber openings of the first intake port and the second intake port, the port radii on the cylinder outer peripheral side intake port region side on the opposite side to the inter-port side are respectively An internal combustion engine comprising: a cylinder outer peripheral side intake air introduction portion that increases or is constant as it advances from the upstream side of the intake port to each of the combustion chamber openings. The cylinder center side intake port region of each of the first intake port and the second intake port is in the vicinity of the combustion chamber opening of each of the intake ports, and the cylinder center side intake port region. 6. A cylinder center side intake introduction portion, wherein a side port radius increases from the upstream side of each intake port to the respective combustion chamber opening, or is constant. Internal combustion engine.

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