JPH04143417A - Intake port for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an intake air quantity from decreasing by forming each intake port being conducted to three intake valves into a simple structure, and reducing a radius of curvature in a bend in proportion as heading for the downstream of this intake port. CONSTITUTION:In a nearly central part in the longitudinal direction of an intake port 2, there is formed a recess 9 facing downward on almost the central bottom surface in the both directions. Each of circular parts 14, 15 are formed at both ends of this recess 9 and they are smoothly connected to each other. In addition, a radius of curvature in each of these circular parts 14, 15 decreases toward a downstream of the intake port 2. Since this port 2 is formed as a single passage with no separate wall in a range from an inlet opening 4 to outlet openings 5, 6, 7, it can prevent any possible increase of intake resistance in the intake port 2. Moreover, since the radius of curvature in each of these circular parts 14, 15 becomes smaller in proportion as going toward the downstream, each air flowing in a central part 11, a left part 12 and a right part 13 will not interfere with each other in and around an intake valve. Thus, such a possibility that an intake air quantity might be decreased is preventable.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an intake port for an internal combustion engine.

[Conventional technology]

Japanese Patent Application Laid-Open No. 60-192859 discloses that three cylinders are used in a single cylinder.
An intake port for an internal combustion engine is disclosed, in which an intake port is provided with three intake valves, and the intake port is separated into three independent intake ports by a separation wall on the side closer to the intake valve.

[Problem to be solved by the invention]

However, since this intake port is separated into three independent intake ports by a separation wall on the side closer to the intake valve, there is a problem in that intake resistance increases.

To solve this problem, removing the separation wall and merging the three intake ports even on the side near the intake valve will cause the intake air flows to interfere with each other and reduce the amount of air taken into the cylinder. This creates the problem of

[Means to solve the problem]

In order to solve the above problems, according to the present invention, in an internal combustion engine having three intake valves in a single cylinder, the intake ports guided to the three intake valves are formed as a single intake port, and the intake ports are formed as a single intake port. A recess is formed at approximately the center in the lateral direction of a cross section that is substantially perpendicular to the longitudinal direction of the port, and the recess and the intake port portions on both sides of the recess are connected by a curved portion that curves upward, and the curved portion increases toward the downstream side of the intake port. We are trying to reduce the radius of curvature of.

[For production]

Since the intake ports guided to the three intake valves are formed as a single intake port, the intake resistance of the intake ports can be reduced. Further, since the radius of curvature of the curved portion decreases toward the downstream side of the intake port, the intake air flows do not interfere with each other near the intake valve.

〔Example〕

Referring to FIG. 8, 1 indicates a cylinder head, 2 indicates an intake port, and 3 indicates an exhaust port. The embodiment shown in FIG. 8 is a five-valve internal combustion engine, and one cylinder is provided with three intake valves and two exhaust valves. The intake port 2 has an inlet opening 4 and three outlet openings 5.6.7, which are opened and closed by each intake valve. The intake port 2 is designed as a single passage from the inlet opening 4 to the outlet opening 5.6.7. The outlet opening 5.6°7 of the intake port 2 is
They are arranged so that their respective centers are located on a circular arc centered on the center of the cylinder 8. Connecting the centers of the outlet openings 5, 6, 7 with straight lines forms an isosceles triangle, and the center of the central outlet opening 6 is located at the vertex of the isosceles triangle.

FIG. 1 is a diagram showing an intake port 2 and an exhaust port 3.

2 to 7 are cross-sectional views taken along the line H-■ to the line ■-■ in FIG. It changes as shown in the figure.

Referring to FIG. 2, the cross-sectional shape of the intake port 2 near the inlet opening 4 is oval. Next, as shown in FIG. 3, a recess 9 is formed downward in the bottom surface of the intake port 2 at approximately the center in the left-right direction, and a recess 9 is formed in the upper surface facing the recess 9. A convex portion 10 is formed. The concave portion 9 gradually becomes deeper toward the downstream side of the intake port 2, and the protrusion amount of the convex portion 10 gradually increases toward the downstream side of the intake port 2. A substantially central portion 11 in the left-right direction of the intake port 2 substantially corresponds to the central outlet opening 6, and a left side 12 and a right side 13 of the central portion 11 correspond to the outlet openings 5 and 7, respectively. There are arcuate portions 1 at both ends of the recess 9.
4 and 15 are formed and smoothly connected. The arcuate portions 14 and 15 are curved upward.

In the cross-sectional shape shown in FIG. 4, the convex portion 1o protrudes greatly, thereby reducing the cross-sectional area of the central portion 11. Further, the radius of the arcuate portions 14 and 15 decreases toward the downstream of the intake port 2.

Furthermore, as shown in FIGS. 5 to 7, the arc portion 14
, 15 are even smaller. In addition, there is a communication passage 16 between the left side 12 and right side 13 and the central part 1 construction.
, 17 gradually become narrower.

The intake port 2 is connected from the inlet opening 4 to the outlet opening 5°6.7
Since it is formed as a single passage without a separating wall, an increase in the intake resistance of the intake port 2 can be prevented.

Air flowing into the intake port 2 from the inlet opening 4 tends to flow through the central portion 11, but the convex portion 10 forces the air flowing through the central portion 11 toward the left side 12 and right side 13. Further, since the radius of the arcuate portions 14 and 15 becomes smaller toward the downstream side, the air flowing in the center portion 11, left side portion 12, and right side portion 13 does not interfere with each other in the vicinity of the intake valve. Thus, an approximately equal amount of air flows into the cylinder 8 from the outlet openings 5.6.7.

As a result of the above, it is possible to prevent the intake air amount from decreasing.

Referring to FIG. 8, the fuel injection valve 20 has two injection ports, which are arranged so as to inject fuel toward the arcuate portions 14 and 15, respectively. This allows the outlet opening 5,
From 6.7 onwards, fuel flows into the cylinder 8 at a predetermined rate.

〔Effect of the invention〕

It is possible to reduce the intake resistance of the intake port and prevent the intake flows from interfering with each other,
This can prevent the amount of intake air from decreasing.

[Brief explanation of the drawing]

Fig. 1 is a side view of the intake port and exhaust port, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, and Fig. 7 are the ■-■ line and ■- of Fig. 1, respectively. ■ line, ■-■ line, v-v line,
FIG. 8 is a cross-sectional view taken along lines 1--2 and 2--2, and a plan view of the intake boat and the exhaust port. 2...Intake port, 9...Recess, 14, 15...
・Arc part.

Claims (1)

[Claims] In an internal combustion engine having three intake valves in a single cylinder, the intake port leading to the three intake valves is formed as a single intake port, and the intake port has a cross section substantially perpendicular to the longitudinal direction of the intake port. A recess is formed approximately in the center in the lateral direction, and the recess and the intake port portions on both sides of the recess are connected by an upwardly curved curved portion, and the radius of curvature of the curved portion is made smaller toward the downstream side of the intake port. intake port of an internal combustion engine.