JP2554755B2 - Intake device in internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake device in which an intake swirl is generated in a combustion chamber of an internal combustion engine when intake air is introduced into the combustion chamber by the shape of an intake port in a cylinder head. It is about.

[Problems to be Solved by Conventional Techniques and Inventions]

One of the methods for improving the ignition / combustibility of the intake air-fuel mixture in the combustion chamber is a method of generating an intake swirl in the combustion chamber due to the shape of the intake port in the cylinder head during intake into the combustion chamber. It is well known that the intake swirl includes one that swirls the intake air laterally around the axis in the cylinder bore in the combustion chamber and one that swirls the intake air vertically in the combustion chamber in the axial direction in the cylinder bore. .

Then, like the latter, as a configuration for vertically rotating the intake air in the axial direction of the cylinder bore,
As shown in the figure, the intake port 2 in the cylinder head 1 is formed in a shape that is curved downward from the side surface 1a of the cylinder head 1 toward the combustion chamber 3, and the intake air is curved at the outer peripheral portion, that is, the intake port 2 Ceiling surface 2a
By flowing along the inside of the combustion chamber 3,
As shown by the one-dot chain line arrow A, the intake
It is configured so as to turn vertically in the direction of the axis 4a in, that is to say, to generate a vertical intake swirl.

However, when the intake valve 5 is opened, the intake port 2 here directly communicates with the combustion chamber 3 when viewed from the direction of the axis 2b, as shown in FIG. As shown, the intake port 2 has a crescent-shaped portion indicated by reference numeral 6 between the inner peripheral surface 2d of the circular opening 2c with respect to the combustion chamber 3 and the outer peripheral surface 5a of the intake valve 5. Is not concentrated on the crescent-shaped communicating portion 6, and a part of the intake air is connected to the crescent-shaped communicating portion 6 as shown by a dotted arrow B in FIG. Flows into the combustion chamber 3 from the opposite side,
The amount of intake air flowing in from the crescent-shaped communication portion 6 is reduced by that much, and the combustion chamber 3 collides with the vertical intake swirl indicated by the arrow A of the alternate long and short dash line.
There is a problem that the vertical intake swirl indicated by the one-dot chain line arrow A in FIG.
The tendency that the vertical intake swirl is diminished as shown in (1) is remarkable in the low load region where the intake amount is small.

Therefore, conventionally, the flow velocity of the intake air in the intake port 2 is improved by reducing the cross-sectional area of the intake port 2, or, for example, JP-A-55-2532.
As described in Japanese Unexamined Patent Application Publication No. 2005-242, etc., in the intake port, the intake air in the intake port is a curved outer peripheral portion, that is,
By providing a drift plate for biasing the inner surface of the intake port 2 so as to flow along the ceiling surface 2a,
The vertical intake swirl indicated by the one-dot chain line arrow A is improved. However, reducing the cross-sectional area of the intake port 2 or providing a deflector plate in the intake port 2 as described above In a high load region where the amount of the engine is large, there is a problem that the output resistance of the internal combustion engine decreases in the high load region because the flow resistance inside the intake port is large and the efficiency of charging the intake chamber with the combustion chamber is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an intake device capable of reliably improving a vertically oriented intake swirl in a combustion chamber without causing an increase in intake flow resistance in an intake port. .

[Means for solving the problem]

To achieve this object, the present invention forms an intake port in a cylinder head on an upper surface of a cylinder block having a cylinder bore in a downward curved shape from a side surface of the cylinder head toward a combustion chamber on a lower surface of the cylinder head. In an internal combustion engine consisting of:
The intake port is formed on the raised bottom surface so as to have a flat cross section, and the height dimension of the raised bottom surface is gradually increased toward the circular opening for the combustion chamber of the intake port. It was done.

[Functions and effects of the invention]

With this configuration, the cross-sectional shape of the intake port is such that, due to the presence of the raised bottom surface, the circular opening of the intake port with respect to the combustion chamber with respect to the combustion chamber when viewed from the direction of its axis It has a shape similar to a crescent-shaped communicating portion that directly communicates with each other, and the intake air in the intake port can be reliably guided over the entire crescent-shaped communicating portion along the ceiling surface of the intake port. Since it is possible to restrict the amount of intake air flowing into the combustion chamber from the portion on the side opposite to the crescent-shaped communicating portion, it is possible to reduce the cross-sectional area of the intake port as in the conventional case, or A strong intake swirl in the vertical direction can be generated in the combustion chamber without providing a deflector plate in the intake port.

Therefore, according to the present invention, it is possible to improve the ignition / combustibility of the intake air / fuel mixture by the intake swirl in the combustion chamber to reduce the charging efficiency in the high load region, and thus to reduce the output of the internal combustion engine in the high load region. It has an effect that can be achieved without fail.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 10 indicates a cylinder block having a cylinder bore 11, and reference numeral 12 indicates a cylinder head fastened to the upper surface of the cylinder block 10, respectively. 12
A combustion chamber 13 that opens into the cylinder bore 11 is recessed on the lower surface of the cylinder head 11, and the intake port 14 has a side surface 12a of the cylinder head 12 and the combustion chamber 1
3 is formed in a downward curved shape so as to open to 3, and a circular opening 14a with respect to the combustion chamber 13 in the intake port 14 is of a poppet type that opens and closes the opening 14a. An intake valve 15 is provided. Reference numeral 16 indicates an exhaust port provided with an exhaust valve 17.

Then, as shown in FIG. 3 and FIG. 4, on the inner bottom surface 14b of the intake port 14, a raised bottom surface 18 formed in an appropriate shape such as an upward convex arc shape is provided along the axial direction of the intake port 14. By providing the intake port 14, the cross-sectional shape of the intake port 14 is formed into a flat shape, and the height dimension H of the raised bottom surface 18 is gradually increased toward the circular opening 14a of the intake port 14 to the combustion chamber 13. To configure.

In this structure, when the intake valve 15 is opened, the intake port 14 has a circular opening with respect to the combustion chamber 13 when viewed from the axial direction thereof, as shown in FIG. The inner peripheral surface 14c of the portion 14a and the intake valve 15
It directly communicates with the outer peripheral surface 15a at a crescent-shaped portion indicated by reference numeral 19.

Therefore, the raised bottom surface 18 is provided on the inner bottom surface 14b of the intake port along the axial direction of the intake port 14 so that the cross section of the intake port 14 is formed into a flat shape. The height dimension H of the intake port 14 is gradually increased toward the circular opening 14a to the combustion chamber 13 in the intake port 14, so that the shape of the cross section of the intake port 14 is As described above, the circular opening 14a in the intake port 14
Has a shape similar to that of the crescent-shaped communicating portion 19 that directly communicates with the combustion chamber 13 when viewed from the direction of the axis, so that the intake air flowing in the intake port 14 in the direction of the axis is It is possible to reliably guide the entire crescent-shaped communicating portion 19 along the ceiling surface 14d of the intake port 14, while the portion opposite to the crescent-shaped communicating portion 19 is indicated by a dotted arrow B. In addition, the amount of intake air flowing into the combustion chamber 13 can be restricted so as to be small.

That is, under the condition that the amount of intake air that flows in is regulated to a small amount as indicated by the dotted arrow B, the amount of intake air that flows in from the crescent-shaped communication portion 19 as indicated by the dashed line arrow A can be significantly increased. Therefore, a vertically strong intake swirl can be generated in the combustion chamber 13.

In addition, in the above embodiment, one intake valve is provided for one combustion chamber 13.
Although the case where 15 is provided and is applied to the intake port 14 for this one intake valve is shown, the present invention is not limited to this, and it is bifurcated into two intake valves provided in one combustion chamber 13. It goes without saying that the invention can also be applied to the intake port configured as described above.

[Brief description of drawings]

1 is a vertical sectional front view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along line II-II of FIG. 1, FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 1, and FIG. 1 is an enlarged sectional view taken along line IV-IV in FIG. 1, FIG. 5 is a vertical sectional front view showing a conventional example, and FIG. 6 is VI-V in FIG.
FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG. 10 …… Cylinder block, 11 …… Cylinder bore, 12 ……
Cylinder head, 13 ... Combustion chamber, 14 ... Intake port, 14
a: opening of the intake port to the combustion chamber, 14b: inner bottom surface of the intake port, 14d: ceiling surface of the intake port, 15: intake valve, 18: arc-shaped raised bottom surface.

Claims (1)

(57) [Claims] 1. An internal combustion engine in which an intake port is formed in a cylinder head on an upper surface of a cylinder block having a cylinder bore in a downward curved shape from a side surface of the cylinder head toward a combustion chamber on a lower surface of the cylinder head. The inner bottom surface of the inner surface of the intake port on the inside of the curve is formed as a raised bottom surface so that the cross-sectional shape of the intake port is formed flat, and the height dimension of the raised bottom surface is defined by the intake port. The intake device for an internal combustion engine, wherein the intake device is configured to gradually increase toward a circular opening for the combustion chamber.