JP2005120998A - Intake port structure of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake port structure of an internal combustion engine capable of suppressing decrease in flow coefficient. <P>SOLUTION: In an intake port structure of an internal combustion engine, an intake port 10 has a vertical passage 12 vertically extending to a combustion chamber top surface 2 so as to open to it and a tilt passage 11 communicating with the vertical passage 12 and extending in the direction tilted in a vertical direction of the combustion chamber top surface 2. A recess 21 is formed in a tilt wall surface 11a which is a lower wall surface of the tilt passage 11. In the recess 21, an end of the combustion chamber side is extended to the boundary D between the tilt passage 11 and the vertical passage 12 so as to be gradually widened toward the combustion chamber side. The end of the combustion chamber side in the recess 21 is provided with a connecting surface 22 in which an edge 31 is formed with respect to a vertical wall surface 12a of the vertical passage 12 to be connected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an intake port structure of an internal combustion engine, and more particularly to an improvement related to the shape of an intake port.

Conventionally, an intake port of an internal combustion engine is formed in a cylinder head, and feeds fluid such as outside air or air-fuel mixture from an intake pipe to a combustion chamber. The intake port is open to the top surface of the combustion chamber and extends perpendicularly to the top surface of the combustion chamber, and is connected to the vertical passage portion and is inclined with respect to the vertical direction of the top surface of the combustion chamber And an inclined passage portion extending in the direction. In recent years, as a technique for generating a strong vortex (swirl) inside the combustion chamber, it has been known that the shape of the intake port is improved and an edge is formed at the boundary between the inclined passage portion and the vertical passage portion. It has been. That is, while the fluid flows along the wall surface of the intake port, the fluid is separated from the wall surface at the portion where the edge is formed and flows toward the wall surface facing the portion. For this reason, the fluid flows in an oblique direction with respect to the combustion chamber and generates a swirl. As such an edge, for example, in Patent Document 1, a flat portion connected to the inclined passage portion at a predetermined angle is formed on the lower wall surface of the boundary portion, and the edge is formed by the flat portion and the vertical passage portion. It is described to form. In Patent Document 2, the wall surface of the inclined passage portion and the wall surface of the vertical passage portion are intersected to form an edge in an angle range of at least 140 degrees on the lower wall surface in the passage cross section, and the inclined passage portion is formed on the upper wall surface. And connecting the wall surface of the vertical passage part with a smooth curved surface.
Japanese Patent Laid-Open No. 10-238401 JP-A-8-42390

  However, when the edge is formed by a method such as projecting a flat portion in the intake port or reducing the diameter of the intake port as in the conventional case, it is very difficult to suppress a decrease in the flow coefficient of the intake port. It is. This reduction in the flow coefficient causes a reduction in the amount of intake air into the combustion chamber, which causes a reduction in the performance of the internal combustion engine.

  That is, the internal combustion engine is manufactured with predetermined design specifications so as to achieve desired performance, and the diameter of the intake port is determined to be a predetermined and sufficient predetermined value based on the design specifications. However, in the above conventional method, the diameter of the intake port must be less than the predetermined value at the portion where the edge is formed, and the flow coefficient inevitably decreases. On the other hand, if the diameter of the intake port is set to the predetermined value at the portion where the edge is formed, the diameter of the intake port must be larger than the predetermined value except for the portion, and the design specification itself is changed. Necessity arises.

  Although forming the edge in this way is effective for improving the performance of the internal combustion engine by strengthening the swirl, on the other hand, it is inevitable that the performance of the internal combustion engine is reduced due to the decrease in the flow coefficient, and the desired performance is achieved. It was difficult to ensure.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an intake port structure of an internal combustion engine that can suppress a decrease in a flow coefficient.

In the following, means for achieving the above-described object and its operational effects are described.
According to a first aspect of the present invention, there is provided a vertical passage portion that opens to the top surface of the combustion chamber and extends perpendicularly to the top surface of the combustion chamber, and is connected to the vertical passage portion and is perpendicular to the vertical direction of the top surface of the combustion chamber. In an intake port structure of an internal combustion engine having an inclined passage portion extending in an inclined direction and constituting an intake port, an end on the combustion chamber side is formed on the lower wall surface of the inclined passage portion and the inclined passage portion and the vertical passage portion And forming a recess that becomes wider toward the combustion chamber side, and at the end of the recess on the combustion chamber side, an edge is formed and connected to the wall surface of the vertical passage portion. The gist is that a connection surface is provided.

  According to the above configuration, the lower wall surface of the inclined passage portion has a concave portion whose end on the combustion chamber side extends to the boundary between the inclined passage portion and the vertical passage portion and becomes wider toward the combustion chamber side. Is formed. And the connection surface which forms an edge with respect to the wall surface of the said vertical channel | path part is provided in the end by the side of the said combustion chamber of this recessed part. That is, this edge is obtained by forming a recess in the wall surface of the inclined passage portion, and the diameter of the intake port is substantially the same in the portion where the edge is formed and in the portion other than where the recess is provided. The flow coefficient is also almost the same value. Therefore, according to the said structure, the fall of a flow coefficient can be suppressed.

  The invention according to claim 2 is the intake port structure of the internal combustion engine according to claim 1, wherein the connection surface is a flat surface and has an arc shape extending in the circumferential direction along the wall surface of the intake port. It is said.

  According to the above configuration, the connection surface is a flat surface and has an arc shape extending in the circumferential direction along the wall surface of the intake port, and the connection surface is at a certain angle with respect to the inner surface of the recess. Keeping connected For this reason, the flow direction of the fluid flowing along the inner surface of the concave portion changes suddenly at the location reaching the connection surface, peels from the connection surface, and moves from the lower wall surface of the inclined passage portion to the upper wall surface facing the stiffening. It becomes easy to flow. In this case, the fluid flows with a strong force from an oblique direction with respect to the combustion chamber, and forms a vertical vortex (tumble) in the combustion chamber. Therefore, according to the above configuration, the swirl can be further strengthened, in particular, the tumble can be strengthened.

  According to a third aspect of the present invention, in the intake port structure of the internal combustion engine according to the first or second aspect, the connection surface is formed with a constant width in the circumferential direction along the wall surface of the intake port. It is a summary.

  According to the above configuration, by forming the connection surface with a constant width, the diameter of the intake port is the same in the portion where the edge is formed and the portion other than the portion where the recess is provided. Therefore, according to the said structure, the fall of a flow coefficient can be suppressed.

  According to a fourth aspect of the present invention, in the intake port structure of the internal combustion engine according to any one of the first to third aspects, the concave portion has a shape that becomes deeper toward the combustion chamber side. It is a summary.

  According to the above configuration, the change in the diameter of the intake port is suppressed to be small between the portion where the recess is provided and the portion other than the portion where the recess is provided. Therefore, according to the above configuration, a change in the flow coefficient in the intake port can be suppressed.

The gist of the invention according to claim 5 is that, in the intake port structure of the internal combustion engine according to any one of claims 1 to 4, the inner surface of the recess is a smooth surface.
According to the above configuration, since the inner surface of the recess is a smooth surface without unevenness, it is possible to suppress unexpected resistance from being added to the fluid, and to appropriately control the flow of the fluid on the inner surface of the recess.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1A shows a longitudinal sectional view of the intake port 10 of the present embodiment, and FIG. 2 shows a transverse sectional view.
As shown in the drawings, the intake port 10 is formed in the cylinder head 1 of the internal combustion engine, and feeds fluid such as outside air and air-fuel mixture from an unillustrated intake pipe to the combustion chamber. The intake port 10 opens to the combustion chamber top surface 2 and extends perpendicularly to the combustion chamber top surface 2, and is connected to the vertical passage portion 12 and is perpendicular to the combustion chamber top surface 2. And an inclined passage portion 11 extending in a direction inclined with respect to. In the intake port 10, a boundary portion D between the inclined passage portion 11 and the vertical passage portion 12 is formed in a curved shape. Hereinafter, unless otherwise specified, in the intake port 10, the combustion chamber side (lower side in FIG. 1 (a)) is the lower side, and the intake pipe side (upper side in FIG. 1 (a)) is the upper side. And

  The intake valve 13 for opening and closing the intake port 10 includes an umbrella portion 13a and a valve shaft 13b. The valve shaft 13b is supported by a valve guide (not shown) provided in the cylinder head 1 so as to be capable of reciprocating in the axial direction. A valve seat 14 on which the umbrella portion 13a can be seated is provided at the opening portion 10a of the intake port 10 to the combustion chamber. The intake port 10 is closed with respect to the combustion chamber when the umbrella portion 13 a is seated on the valve seat 14, and is opened with respect to the combustion chamber when the umbrella portion 13 a is separated from the valve seat 14.

  A concave portion 21 is provided along the inclined wall surface 11a on the inclined wall surface 11a which is a lower wall surface in the inclined passage portion 11. The concave portion 21 is formed in a shape that becomes wider as it goes downward, that is, in an inverted V shape in plan view. Further, the inner surface 21a of the recess 21 is formed to be a smooth surface. This is because the flow of the fluid is suitably controlled by the inner surface 21a by suppressing an unexpected resistance from being applied to the fluid flowing along the inner surface 21a of the recess 21. The lower end of the recess 21 extends to the boundary portion D between the inclined passage portion 11 and the vertical passage portion 12.

  FIG. 1B shows a longitudinal sectional view of the recess 21 in the intake port 10 of the present embodiment. In the figure, the depth of the recess 21 is exaggerated for easy understanding of the shape of the recess 21.

  As shown in the figure, a connection surface 22 is provided at the lower end of the recess 21. The connection surface 22 is configured to connect the inner surface 21 a of the recess 21 in a stepped manner to the vertical wall surface 12 a that is the lower wall surface of the vertical passage portion 12. That is, the concave portion 21 is formed to have a shape that becomes deeper toward the vertical passage portion 12 side by notching a corresponding portion (indicated by a two-dot chain line in FIG. 1B) on the inclined wall surface 11a. Has been. For this reason, there is necessarily a step between the inner surface 21a of the recess 21 and the vertical wall surface 12a, and a connection surface 22 is formed to connect the inner surface 21a to the vertical wall surface 12a.

  The connection surface 22 is a flat surface and is formed so as to be connected to the inner surface 21a of the recess 21 in an obtuse angle. Further, the connection surface 22 has an arc shape extending in the circumferential direction along the wall surface of the intake port 10 in a plan view, and is connected to the inner surface 21a so as to maintain a constant angle therebetween. Yes. The connection surface 22 is formed with a constant width in the circumferential direction along the wall surface of the intake port in plan view. The connection surface 22 formed in this way is connected to the vertical wall surface 12a at an obtuse angle, and an edge 31 is formed by the boundary between the connection surface 22 and the vertical wall surface 12a.

Next, the flow of fluid in the intake port 10 will be described.
As shown in FIG. 1B, the fluid sent to the intake port 10 first flows along the inclined wall surface 11 a until reaching the recess 21. Thereafter, the fluid flows along the inner surface 21a of the recess 21 while changing the flow direction in the recess 21 without maintaining the flow (the arrow indicated by the two-dot chain line in the drawing) along the inclined wall surface 11a. The flow (arrow indicated by a solid line in the figure) reaches the connection surface 22. The concave portion 21 has an inverted V shape in plan view, that is, a shape in which the flow coefficient increases as it goes toward the vertical passage portion 12, and therefore it is difficult to add resistance to the fluid flowing through the concave portion 21. Separation of the fluid with respect to the inner surface 21a is suppressed, and the fluid preferably flows along the inner surface 21a of the recess 21.

  Thereafter, the connection surface 22 is connected to each of the inner surface 21a and the vertical wall surface 12a of the concave portion 21 at an obtuse angle, and the flow direction changes suddenly. Flows above port 10. Then, this fluid joins with the fluid flowing along the upper wall surface of the intake port 10 and flows into the combustion chamber with a strong force from an oblique direction, thereby forming a vertical vortex (tumble) in the combustion chamber. .

  The edge 31 extends from an intermediate portion of the inclined wall surface 11a to a boundary portion D with the vertical wall surface 12a in a state where the intake port 10 is formed so that the inclined passage portion 11 and the vertical passage portion 12 have substantially the same diameter. Is formed into a reverse V shape by forming a recess 21. Therefore, as shown in FIG. 1A, the diameter R1 of the portion other than the inclined passage portion 11 provided with the recess 21 and the diameter R2 of the vertical passage portion 12 where the edge 31 is provided are: Since the processing related to the formation of the recess 21 is not added, the same length is maintained. In particular, by forming the connection surface 22 with a constant width in the circumferential direction along the wall surface of the intake port 10, the change in the diameter R2 is reliably suppressed. For this reason, the end portion on the intake pipe side in the intake port 10 and the portion where the edge 31 is provided have the same flow coefficient, and a decrease in the flow coefficient is suppressed.

  Moreover, the said recessed part 21 is formed in the reverse V shape by planar view so that it may become wide as it goes below. That is, a portion where the diameter of the intake port is expanded by the concave portion 21 is set to a smaller range than the same portion due to the concave portion formed with an equal width. Accordingly, the diameter of the intake port is expanded, in other words, the range in which the flow coefficient changes is minimized. Furthermore, the depth of the recess 21 does not exceed the thickness of the cylinder head 1 even if it is the maximum value, and the diameter of the intake port does not greatly expand by providing the recess 21. Therefore, the influence on the diameter of the intake port by providing the recess 21 is very small.

According to the intake port structure of the present embodiment described above, the following effects can be obtained.
(1) Even when the edge 31 is formed, the diameter R2 of the vertical passage portion 12 at the closest position of the edge 31 and the diameter R1 of the portion other than the concave passage 21 provided in the inclined passage portion 11 are maintained at substantially the same value. Has been. Accordingly, it is possible to suppress a decrease in the flow coefficient at the portion where the edge 31 is formed in the intake port 10.

  (2) Since the connection surface 22 is formed as a flat surface, the connection surface 22 is connected to the inner surface 21a of the recess 21 in an obtuse angle. Therefore, the fluid is preferably peeled off at the edge 31 and tumbled in the combustion chamber. Can be formed.

  (3) Since the connection surface 22 is formed in an arc shape extending in the circumferential direction along the inclined wall surface 11a, the connection surface 22 is connected to the inner surface 21a at a constant angle. Thus, the air can be collected above the intake port 10. Therefore, the tumble can be reliably formed in the combustion chamber.

  (4) Since the connecting surface 22 is formed with a constant width, the diameter R2 of the vertical passage portion 12 at the closest position of the edge 31 is equal to the diameter R1 of the portion other than the inclined passage portion 11 where the recess 21 is provided. Can be held as it is. Accordingly, it is possible to prevent a decrease in the flow coefficient at the portion where the edge 31 is formed in the intake port 10.

(5) Since the concave portion 21 has a shape that becomes deeper toward the vertical passage portion 12 side, a change in the flow coefficient in the intake port 10 due to the formation of the concave portion 21 can be suitably suppressed.
(6) By making the inner surface of the concave portion 21 a smooth surface having no irregularities, the flow of fluid can be suitably controlled.

In addition, this embodiment can also be changed and embodied as follows.
-You may connect with the acute angle shape with respect to the inner surface 21a, making the said connection surface 22 into the flat surface. Alternatively, the connection surface 22 may be a curved surface and connected to the inner surface 21a in an arc shape. From the viewpoint of strengthening the tumble, the connection surface 22 is preferably a flat surface as in the present embodiment. In other words, when the connection surface 22 is connected to the inner surface 21 a in an arc shape, the fluid is guided from the flow to the connection surface 22 and may not be peeled off from the connection surface 22.

  The connection surface 22 is not limited to a constant width as in the present embodiment, and may have an arbitrary width at each location as long as there is no significant difference between the diameter R2 and the diameter R1. It may be formed.

The recess 21 is not limited to an inverted V shape in a plan view of the embodiment, and may be, for example, an inverted U shape, an inverted Y shape, or the like, as long as the recess 21 has a shape that becomes wider toward the vertical passage portion 12.
-You may form the recessed part 21 so that it may become a fixed depth.

  The inner surface of the recess 21 may be an uneven rough surface as long as it does not affect the flow of fluid.

(A) is a longitudinal cross-sectional view which shows an intake port, (b) is a longitudinal cross-sectional view which shows a recessed part. The plane sectional view showing an intake port.

Explanation of symbols

  D: Boundary portion, 2 ... Combustion chamber top surface, 10 ... Intake port, 11 ... Inclined passage portion, 11a ... Inclined wall surface as a lower wall surface of the inclined passage portion, 12 ... Vertical passage portion, 12a ... Wall surface of the vertical passage portion A vertical wall surface, 21 ... a recess, 21a ... an inner surface of the recess, 22 ... a connection surface, 31 ... an edge.

Claims (5)

A vertical passage portion that opens to the top surface of the combustion chamber and extends perpendicularly to the top surface of the combustion chamber, and an inclined passage portion that extends in a direction inclined to the vertical direction of the top surface of the combustion chamber while continuing to the vertical passage portion In the intake port structure of the internal combustion engine that constitutes the intake port with
In the lower wall surface of the inclined passage portion, an end on the combustion chamber side is extended to a boundary portion between the inclined passage portion and the vertical passage portion, and a concave portion that becomes wider toward the combustion chamber side is formed. An intake port structure for an internal combustion engine, characterized in that a connection surface is formed at the end on the combustion chamber side of the vertical passage portion so as to form an edge to the wall surface of the vertical passage portion. 2. The intake port structure for an internal combustion engine according to claim 1, wherein the connection surface is a flat surface and has an arc shape extending in a circumferential direction along a wall surface of the intake port. The intake port structure for an internal combustion engine according to claim 1 or 2, wherein the connection surface is formed with a constant width in the circumferential direction along a wall surface of the intake port. The intake port structure for an internal combustion engine according to any one of claims 1 to 3, wherein the recess has a shape that becomes deeper toward the combustion chamber side. The intake port structure for an internal combustion engine according to any one of claims 1 to 4, wherein an inner surface of the recess is a smooth surface.

Images